JP2002291264A - Piezoelectric actuator, driving device of piezoelectric actuator, driving method of same and mobile equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator small and thin size and capable of high efficient and stable driving. SOLUTION: A drive circuit 500A computes a differential signal Vc of detection signals Va, Vb in response to the distortion of a vibration plate 10 from detection poles 34A, 34B by a subtraction circuit 501, and generates a delay signal 502 delayed by a predetermined time tp by a delay circuit 502. A comparator 503 is input by the differential signal Vc and a delay signal Vd, and a signal Ve resulting in comparison of a large and small voltages is supplied to a voltage adjustment circuit 504. The voltage adjustment circuit 504, VCO 504, and driver circuit 506 generates a drive signal Vh of frequency based on this comparison result signal Ve. Therefore, the drive circuit 500A detects distortion of the vibration plate 10 and controls the frequency of the drive signal Vh so that the vibration plate 10 is always vibrated in maximum with this distortion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric actuator having a piezoelectric element, a driving device for the piezoelectric actuator,
The present invention relates to a driving method of a piezoelectric actuator, a timepiece, and a portable device.

[0002]

2. Description of the Related Art Various types of piezoelectric actuators utilizing the piezoelectric effect of piezoelectric elements have been developed recently because piezoelectric elements have excellent conversion efficiency from electric energy to mechanical energy and excellent responsiveness. This piezoelectric actuator includes a piezoelectric buzzer, a printer inkjet head,
Alternatively, it is applied to fields such as ultrasonic motors.

[0003] The displacement of the piezoelectric element is very small, depending on the voltage value of the supplied drive signal, and is usually on the order of submicron. For this reason, it has been performed to amplify the displacement by some kind of amplifying mechanism and transmit the displacement to a driven object. However, when the amplification mechanism is used, there is a problem that energy is consumed to move itself and the efficiency is reduced, and further, there is a problem that the size of the device is increased. In addition, in the case of via an amplification mechanism, it may be difficult to transmit a stable driving force to a driving target.

[0004] In addition, since small portable devices such as wristwatches are driven by batteries, it is necessary to reduce power consumption and the voltage value of drive signals. When a piezoelectric actuator is incorporated in such a portable device, it is particularly required that the piezoelectric actuator has a high energy efficiency and a low drive signal voltage value.

[0005]

A clock or the like is provided with a calendar display mechanism for displaying a date and a day of the week. Some of these calendar display mechanisms do not require date correction at the end of the month, and this is called an automatic calendar mechanism. The display operation of the automatic calendar mechanism generally drives a date indicator or a day indicator using the rotational driving force of an electromagnetic stepping motor provided separately from the hand operation. On the other hand, a wristwatch is carried around by wrapping a belt around a wrist, and there has been an old demand for a thin wristwatch so as to be convenient to carry. This request is the same even in a wristwatch equipped with an automatic calendar display mechanism. However, when compared with a wristwatch without such a mechanism, a wristwatch equipped with an auto-calendar display mechanism requires a space for separately providing a drive source for date display, and a stepping motor is used as a drive source for the auto-calendar display mechanism. In the case of using, it is very difficult to reduce the thickness while securing the space.

Therefore, as an actuator which can be mounted on a small device while having high efficiency, a piezoelectric element is driven in a longitudinal direction by applying a drive signal to a diaphragm composed of a thin rectangular piezoelectric element or the like. 2. Description of the Related Art A piezoelectric actuator that excites longitudinal vibration by expanding and contracting and mechanically induces bending vibration by the longitudinal vibration has been proposed. In such a piezoelectric actuator, by causing both the longitudinal vibration and the bending vibration on the vibration plate, a portion of the piezoelectric actuator that contacts the drive target is moved in an elliptical orbit. Thus, the piezoelectric actuator realizes highly efficient driving while having a small and thin configuration.

However, as described above, the piezoelectric actuator electrically excites the longitudinal vibration with respect to the diaphragm, and mechanically induces the bending vibration by the longitudinal vibration. For this reason, the longitudinal vibration caused by the expansion and contraction of the piezoelectric element by applying the drive signal can be controlled relatively easily by controlling the voltage value of the drive signal, but according to the mechanical characteristics of the diaphragm. It is difficult to control easily and accurately the flexural vibration induced. For this reason, it is conceivable that the stability of the product is lost, such as variation in bending vibration induced due to variations in processing accuracy of the diaphragm. Further, since the bending vibration is determined by mechanical characteristics determined by the shape of the diaphragm, it has been difficult to obtain a bending vibration having a stable amplitude under mechanical conditions such as the determined shape.

The present invention has been made in view of the above circumstances, and has a structure that can be reduced in size and thickness.
It is an object of the present invention to provide a piezoelectric actuator, a driving device for a piezoelectric actuator, a driving method for a piezoelectric actuator, a timepiece including the piezoelectric actuator, and a portable device that can perform highly efficient and stable driving.

[0099]

In order to solve the above-mentioned problems, a piezoelectric actuator according to the present invention is characterized in that when a driving signal is supplied, a longitudinal vibration and a bending vibration which vibrates in a direction substantially orthogonal to the longitudinal vibration are obtained. A vibration plate having at least one piezoelectric element that generates
A contact portion that is in contact with the drive target, and a piezoelectric actuator that drives the drive target by displacement of the contact portion accompanying the longitudinal vibration and the bending vibration,
The vibration plate is provided with a distortion detection unit that detects distortion of the vibration plate when driving the driving target.

According to this configuration, the piezoelectric element expands and contracts in the diaphragm by the supplied drive signal, and a longitudinal vibration along the longitudinal direction is excited on the diaphragm, and a bending vibration is induced with the longitudinal vibration. . For example, if the frequency of the drive signal is corrected using the detection signal detected from the distortion detection unit, it is possible to generate stable vibration on the diaphragm. In the configuration of the piezoelectric actuator, it is not necessary to adopt a structure in which various members are stacked in the thickness direction, so that it is easy to reduce the size and thickness.

In this configuration, a line extending in the direction of the longitudinal vibration is defined as a horizontal line, extends in a direction perpendicular to the horizontal line through a point serving as a node of the vertical vibration, and is viewed from the horizontal line of the diaphragm. A line that divides a portion located on the opposite side of the contact portion into two portions having the same weight is defined as a vertical line, and the intersection of the vertical line and the horizontal line is point-symmetric with the contact portion. It is preferable to provide a balance adjusting portion at a position and for giving a difference in weight between the two portions to at least one of the portions.

In this configuration, it is preferable that a support member is provided on the diaphragm at a portion serving as a node of the longitudinal vibration.

In this configuration, the strain detecting section is disposed on the side of the contact portion as viewed from a horizontal line passing through a portion of the vibration plate that is a node of the longitudinal vibration and extending in a direction orthogonal to the vibration direction of the longitudinal vibration. It is preferable to arrange them.

In this configuration, the strain detecting section is disposed on the contact portion side as viewed from a horizontal line passing through a portion of the diaphragm that becomes a node of the longitudinal vibration and extending in a direction orthogonal to the vibration direction of the longitudinal vibration. It is preferable to include a first detection unit disposed and a second detection unit disposed on a side of the diaphragm opposite to the contact portion when viewed from the horizontal line.

In this configuration, it is preferable that the strain detecting section includes a detecting electrode and a portion of the piezoelectric element on which the detecting electrode is arranged.

In this configuration, it is preferable that the distortion detecting section is a piezoelectric sensor arranged on a surface of the piezoelectric element.

A driving device for a piezoelectric actuator according to the present invention has at least one piezoelectric element that generates a longitudinal vibration and a bending vibration that vibrates in a direction substantially orthogonal to the longitudinal vibration when a driving signal is supplied. A diaphragm, a contact portion provided on the diaphragm, which is in contact with a driven object, and a distortion detecting unit provided on the diaphragm, which detects distortion of the diaphragm when driving the driven object. A driving device for a piezoelectric actuator that drives the driven object by displacement of the abutting portion caused by the longitudinal vibration and the bending vibration, wherein the driving signal has been subjected to frequency correction based on a control signal. And a control signal generator for generating the control signal based on the signal detected from the distortion detector.

In this configuration, the drive signal generation section includes a voltage controlled oscillation circuit that outputs a reference signal having a frequency corresponding to a voltage value of the control signal, and a driver that generates the drive signal based on the reference signal. And a circuit.

In this configuration, the strain detecting portion is disposed on the contact portion side when viewed from a horizontal line passing through a portion of the diaphragm that becomes a node of the longitudinal vibration and extending in a direction orthogonal to the vibration direction of the longitudinal vibration. The control signal generator includes a peak hold circuit that detects a maximum value of amplitude among the detected signals and outputs a peak signal, and a delay circuit that outputs a delay signal obtained by delaying the peak signal by a predetermined time. A comparison circuit that compares the voltage value of the peak signal with the voltage value of the delay signal to output a comparison result signal, and adjusts the voltage value of the control signal in units of a predetermined voltage value in response to the comparison result signal And a voltage adjusting circuit.

In this configuration, the strain detecting portion is disposed on the contact portion side as viewed from a horizontal line passing through a portion of the diaphragm that becomes a node of the longitudinal vibration and extending in a direction perpendicular to the vibration direction of the longitudinal vibration. The control signal generator detects a phase difference between the phase of the detected signal and the phase of the drive signal, and outputs a phase difference voltage signal having a voltage value corresponding to the phase difference. A voltage conversion circuit, a delay circuit that outputs a delay signal obtained by delaying the phase difference voltage signal by a predetermined time, and compares a voltage value of the phase difference voltage signal with a voltage value of the delay circuit to output a comparison result signal And a voltage adjusting circuit that receives the comparison result signal and adjusts the voltage value of the control signal in units of a predetermined voltage value.

In this configuration, the strain detecting portion is disposed on the contact portion side as viewed from a horizontal line passing through a portion of the diaphragm that becomes a node of the longitudinal vibration and extending in a direction orthogonal to the vibration direction of the longitudinal vibration. The control signal generator detects a phase difference between the phase of the detected signal and the phase of the drive signal, and outputs a phase difference voltage signal having a voltage value corresponding to the phase difference. A voltage conversion circuit, a constant voltage circuit that outputs a reference phase difference signal having a voltage corresponding to a predetermined reference phase difference between the phase of the detection signal and the phase of the drive signal, the phase difference voltage signal and the reference position. It is preferable to include a comparison circuit that compares the phase difference signal and outputs a comparison result signal, and a voltage adjustment circuit that receives the comparison result signal and adjusts the voltage value of the control signal in units of a predetermined voltage value. .

In this configuration, the strain detecting section is disposed on the contact portion side as viewed from a horizontal line passing through a portion of the diaphragm that becomes a node of the longitudinal vibration and extending in a direction orthogonal to the vibration direction of the longitudinal vibration. A first detection unit disposed; and a second detection unit disposed on the opposite side of the abutting portion when viewed from the horizontal line of the diaphragm, wherein the control signal generation unit includes the first detection unit A subtraction circuit that outputs a difference signal from a difference between signals detected from the second detection unit, a delay circuit that outputs a delay signal obtained by delaying the difference signal by a predetermined time, a voltage value of the difference signal, and the delay circuit. And a voltage adjustment circuit that receives the comparison result signal and adjusts the voltage value of the control signal in units of a predetermined voltage value. preferable.

A driving method of a piezoelectric actuator according to the present invention has at least one piezoelectric element that generates a longitudinal vibration and a bending vibration that vibrates in a direction substantially orthogonal to the longitudinal vibration when a driving signal is supplied. A diaphragm, a contact portion provided on the diaphragm, which is in contact with a driven object, and a distortion detecting unit provided on the diaphragm, which detects distortion of the diaphragm when driving the driven object. A driving method of a piezoelectric actuator that drives the driven object by a displacement of the contact portion caused by the longitudinal vibration and the bending vibration, wherein the driving signal is frequency-corrected based on a control signal. And a control signal generating step of generating the control signal based on the signal detected from the distortion detecting section.

In this configuration, the strain detecting section is arranged on the side of the abutting section as viewed from a horizontal line passing through a portion of the diaphragm that serves as a node of the longitudinal vibration and extending in a direction orthogonal to the vibration direction of the longitudinal vibration. Preferably, the control signal generating step calculates a maximum value of the amplitude of the detected signals, and generates the control signal based on the maximum value.

In this configuration, the strain detecting portion is disposed on the contact portion side when viewed from a horizontal line passing through a portion of the diaphragm that becomes a node of the longitudinal vibration and extending in a direction perpendicular to the vibration direction of the longitudinal vibration. Preferably, in the control signal generation step, a phase difference between a phase of the detected signal and a phase of the drive signal is calculated, and the control signal is generated from the phase difference.

In this configuration, the strain detecting section is disposed on the contact portion side as viewed from a horizontal line passing through a portion of the diaphragm that becomes a node of the longitudinal vibration and extending in a direction orthogonal to the vibration direction of the longitudinal vibration. A first detection unit disposed, and a second detection unit disposed on a side of the diaphragm opposite to the contact unit when viewed from the horizontal line, wherein the control signal generation step includes the first detection unit , A difference between signals detected from the second detection unit, and generating the control signal from the difference.

A timepiece according to the present invention includes a diaphragm having at least one piezoelectric element that generates a longitudinal vibration and a bending vibration that vibrates in a direction substantially perpendicular to the longitudinal vibration when a driving signal is supplied thereto; A contact portion provided on the diaphragm and abutted against a driven object; and a distortion detecting unit provided on the diaphragm and detecting distortion of the diaphragm when driving the driven object. A piezoelectric actuator that drives the driven object by the displacement of the abutting portion due to the longitudinal vibration and the bending vibration, and a drive signal generation unit that generates the drive signal that has been subjected to frequency correction based on a control signal,
A driving device having a control signal generation unit for generating the control signal based on a signal detected from the distortion detection unit; a calendar display wheel driven by the piezoelectric actuator; and a power supply for supplying power to the driving device And characterized in that:

A portable device according to the present invention includes a diaphragm having at least one piezoelectric element that generates a longitudinal vibration and a bending vibration that vibrates in a direction substantially orthogonal to the longitudinal vibration when supplied with a drive signal. A contact portion provided on the diaphragm, abutting on a driven object, provided on the diaphragm,
A piezoelectric actuator, comprising: a distortion detection unit that detects distortion of the diaphragm when driving the driving target; and a piezoelectric actuator that drives the driving target by displacement of the contact unit accompanying the longitudinal vibration and the bending vibration. And, based on a signal detected from the drive signal generation unit that generates the drive signal subjected to frequency correction based on the control signal, and the distortion detection unit,
A driving device having a control signal generation unit for generating the control signal; and a battery for supplying power to the driving device.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a wristwatch provided with a calendar display mechanism driven by a piezoelectric actuator according to the present invention will be exemplified. A. Overall Configuration First, FIG. 1 is a plan view showing a main configuration of a calendar display mechanism incorporating a piezoelectric actuator in a wristwatch according to an embodiment of the present invention. As shown in the figure, the piezoelectric actuator A includes a diaphragm 10 that expands and contracts in an in-plane direction (a direction parallel to the plane of the drawing). Further, the rotor 100 to be driven is rotatably supported by the ground plate (support) 103 and is disposed at a position where the rotor 100 comes into contact with the vibration plate 10. It is driven to rotate in the direction indicated by the arrow in the figure.

Next, the calendar display mechanism includes the rotor 100
, And is driven by the driving force of the rotor 100. A main part of the calendar display mechanism is generally constituted by a reduction gear train for reducing the rotation of the rotor 100 and a ring-shaped date dial 50. The reduction gear train includes a date turning intermediate wheel 40 and a date turning wheel 60.

When the diaphragm 10 vibrates in the in-plane direction as described above, the rotor 1 in contact with the diaphragm 10
00 is rotated clockwise. The rotation of the rotor 100 is transmitted to the date indicator wheel 60 via the date indicator intermediate wheel 40, and the date indicator wheel 60 rotates the date indicator wheel 50 clockwise. As described above, the transmission of the force from the diaphragm 10 to the rotor 100, the transmission of the force from the rotor 100 to the reduction gear train, and the transmission of the force from the reduction gear train to the date wheel 50 are all performed in the in-plane direction. Therefore, the thickness of the calendar display mechanism can be reduced.

FIG. 2 is a sectional view of a timepiece according to an embodiment of the present invention. In the figure, a calendar display mechanism provided with the above-described piezoelectric actuator A is incorporated in a mesh portion, and the thickness D in which the calendar display mechanism is incorporated is extremely thin in order to make the entire timepiece thin. A disk-shaped dial 70 is provided above the calendar display mechanism.
A window 71 for displaying a date is provided on a part of the outer peripheral portion of the dial 70 so that the date of the date dial 50 can be seen through the window 71. A movement 73 for driving the hands 72 and a drive circuit (not shown) to be described later are provided below the dial 70.

In the above configuration, the piezoelectric actuator A has a configuration in which the diaphragm 10 and the rotor 100 are arranged in the same plane, instead of stacking coils and rotors in the thickness direction unlike a conventional stepping motor. I have. Therefore, the structure is formed thinner than a stepping motor or the like. Thus, the thickness of the entire timepiece can be reduced by reducing the thickness of the calendar display mechanism. For example, various wristwatches having a power generation function have been proposed in recent years. In such a wristwatch, at least two large components such as a power generation mechanism and a motor mechanism for driving the hand movement must be mounted. It can be said that the merit of reducing the thickness of the calendar display mechanism is great. Further, by reducing the thickness of the calendar display mechanism, the movement 73 can be shared between a timepiece having a calendar display mechanism and a timepiece having no such display mechanism, thereby increasing productivity.

B. Configuration of Calendar Display Mechanism Next, the configuration of the calendar display mechanism will be described with reference to FIG. 1 and FIG. In the figure, a base plate 103 is a first bottom plate for arranging each component,
The bottom plate 103 ′ is a second bottom plate having a step partially with respect to the bottom plate 103.

Above the rotor 100, which is driven to rotate by the piezoelectric actuator A, is coaxial with the rotor 100,
And a gear 100c rotated by the rotor 100
Is provided. The date turning intermediate wheel 40 includes a large-diameter portion 4b and a small-diameter portion 4a which is fixed concentrically with the large-diameter portion 4b and has a slightly smaller diameter than the large-diameter portion 4b. With rotation, gear 1
The large diameter portion 4b meshing with the intermediate wheel 4c is rotated.
0 is rotated. The peripheral surface of the small diameter portion 4a is cut out in a substantially square shape, and a cutout portion 4c is formed.

The date intermediate wheel 40 is provided on the bottom plate 103 '.
And a bearing (not shown) connected to the shaft 41 is formed inside the date turning intermediate wheel 40. Therefore, the date intermediate wheel 40 is connected to the bottom plate 10.
3 'is provided rotatably with respect to 3'. The rotor 100 also has a bearing (not shown) inside, and
3 and is rotatably supported.

Next, the date dial 50 has a ring shape, and an internal gear 5a is formed on an inner peripheral surface thereof. The date wheel 60 has a five-tooth gear and meshes with the internal gear 5a. A shaft 61 is provided at the center of the date driving wheel 60.
Are provided, and the date wheel 60 is rotatably supported. The shaft 61 is loosely inserted into a through hole 62 formed in the bottom plate 103 '. The through hole 62 is formed to be long along the rotation direction of the date indicator 50.

Next, one end of the leaf spring 63 is connected to the bottom plate 10.
3 ', and the other end presses the shaft 61 in the upper right direction in FIG. Thus, the leaf spring 63 biases the shaft 61 and the date wheel 60. Further, swinging of the date wheel 50 is prevented by the urging action of the leaf spring 63.

Next, one end of the leaf spring 64 has a bottom plate 103 '.
The other end is formed with a distal end portion 64a bent in a substantially V-shape. The contact 65 is arranged so as to come into contact with the leaf spring 64 when the date turning intermediate wheel 40 rotates and the tip end portion 64a enters the notch 4c. A predetermined voltage is applied to the leaf spring 64. When the leaf spring 64 comes into contact with the contact 65, the voltage is applied to the contact 6.
5 is also applied. Therefore, the date feeding state can be detected by detecting the voltage of the contact 65.
Note that a manually driven wheel that meshes with the internal gear 5a may be provided, and the date wheel 50 may be driven when the user performs a predetermined operation on the crown (not shown).

C. Piezoelectric actuator C1. Schematic Configuration of Piezoelectric Actuator Next, the piezoelectric actuator A according to the present embodiment will be described. As shown in FIG.
Is a long plate-shaped diaphragm 10 formed long in the left-right direction of the drawing.
And a support member 11 for supporting the diaphragm 10 on the ground plate 103 (see FIGS. 1 and 3).

A contact portion 36 is provided at the longitudinal end 35 of the diaphragm 10 so as to protrude toward the rotor 100. The contact portion 36 is formed on the outer periphery of the rotor 100 by a spring member 300 described later. It is brought into contact with the surface while being pressed. By providing such a contact portion 36, the contact portion 36 is maintained in order to maintain the state of the contact surface with the rotor 100.
Since it is only necessary to perform operations such as polishing on the
The management of the contact portion with 00 becomes easy. The contact portion 36
Can be used, a conductor or a non-conductor can be used. However, if it is made of a non-conductor, the piezoelectric element 3 can be made even when it comes into contact with the rotor 100 which is generally made of metal.
0, 31 can be prevented from being short-circuited.

As shown in the figure, in the present embodiment, the contact portion 36 has a curved shape protruding toward the rotor 100 when viewed in plan. In this manner, by making the contact portion 36 that contacts the rotor 100 a curved surface, the rotor 10
Even if the positional relationship between 0 and the diaphragm 10 fluctuates due to dimensional variations or the like, the contact state between the curved outer peripheral surface of the rotor 100 and the curved contact portion 36 does not change much. . Thus, the contact between the rotor 100 and the contact portion 36 is maintained in a stable state.

Near the center in the longitudinal direction of the diaphragm 10,
One end 37 of the substantially L-shaped support member 11 is attached. The support member 11 is bent from one end 37 to the rotor 100 side in a direction substantially perpendicular to the longitudinal direction of the diaphragm 10, and the other end 38 of the bent support member 11 is
The shaft portion 39 is rotatably supported on the base plate 103 (see FIG. 1). That is, since the support member 11 is freely rotatable about the shaft 39, the diaphragm 10 can be pressed against the rotor 100 by the spring member 300 with a desired pressing force. Further, the support member 11 may be formed integrally with an auxiliary plate 32 described later, which constitutes the diaphragm 10.

A spring member 300 is provided on a portion 11a of the support member 11 extending substantially in parallel with the longitudinal direction of the diaphragm 10.
Is engaged at one end 300a. The spring member 300 is fixed to the base plate 103 by a pin 300b at a substantially central portion thereof.
(See FIGS. 1 and 3).
The other end 300c is engaged with the main plate 103,
The pressing force applied to the support member 11 can be changed depending on the position of the other end 300c. Specifically, if the other end 300c is displaced clockwise in the drawing around the pin 300b, the force of the one end 300a of the spring member 300 pressing the portion 11a of the support member 11 upward increases. When the other end 300c is displaced counterclockwise, the pressing force is reduced. Here, the support member 1
1 increases, the force of the support member 11 to rotate counterclockwise about the shaft 39 in the figure increases, so that the contact portion 36 presses the rotor 100. Increase. On the other hand, when the force for pressing the support member 11 upward decreases, the force for the support member 11 to rotate in the counterclockwise direction decreases.
The force pressing 00 is reduced. That is, by adjusting the position of the other end portion 300c, the contact portion 36
Of the piezoelectric actuator A can be adjusted.

As shown in FIG. 5, the vibration plate 10 has substantially the same shape as the piezoelectric elements 30, 31 between two rectangular piezoelectric elements 30, 31.
It has a laminated structure in which a reinforcing plate 32 made of stainless steel or the like thinner than 31 is arranged. Thus, the piezoelectric element 3
By arranging the reinforcing plate 32 between 0 and 31, damage to the diaphragm 10 due to an external impact force due to excessive amplitude or dropping of the diaphragm 10 is reduced, and durability is improved. Further, as the reinforcing plate 32, the piezoelectric elements 30, 31
By using a thinner element, the piezoelectric element 3
The vibration of 0, 31 is prevented as much as possible. In addition,
If the support member 11 described above is formed integrally with the reinforcing plate 32, the manufacturing process can be simplified.

As shown in FIG. 6, electrodes 33 are arranged on the surfaces of the piezoelectric elements 30, 31 arranged vertically so as to cover almost the entire surfaces of the piezoelectric elements 30, 31, respectively. Then, the piezoelectric element 30,
A drive signal is supplied to the drive circuit 31 from the drive circuit 500. Here, as the piezoelectric elements 30 and 31,
Lead zirconate titanate (PZT ™), quartz,
Various materials such as lithium niobate, barium titanate, lead titanate, lead metaniobate, polyvinylidene fluoride, lead zinc niobate, and lead scandium niobate can be used. Here, the composition formula of lead zinc niobate is [P
b (Zn _1/3 -Nb _2/3 ) O ₃ ) _1-X (PbTi
O ₃ ) _X ], where X varies depending on the composition and X = 0.09, and the composition formula of lead scandium niobate is
[｛Pb ((Sc _1/2 -Nb _1/2 ) _1-x Ti _x ) O ₃ ],
(However, X differs depending on the composition, and X = 0.09).

When the polarization directions of the piezoelectric elements 30 and 31 are opposite, for example, as shown in FIG. 7, the potentials of the upper surface, the center and the lower surface are + V, 0 and + V (or -V, 0 and -V), respectively. If a drive signal is applied from the drive circuit 500 so that
The plate-like piezoelectric element is displaced so as to expand and contract, and the present embodiment utilizes such displacement due to expansion and contraction. When the polarization directions of the piezoelectric elements 30 and 31 are set to be the same, the potentials of the upper surface, the center, and the lower surface are respectively +
A voltage may be applied so as to be V, 0, -V (or -V, 0, + V).

Further, on the surface of the diaphragm 10, detection electrodes 34A and 34B are formed at certain predetermined positions (see FIG. 20). In this case, the detection electrodes 34A, 34B
Form electrodes on the front surface of the piezoelectric element 30 and
The portions 4A and 34B may be formed so as to be insulated from the electrode 33. The detection electrodes 34A and 34B detect vibration generated in the diaphragm 10 as distortion.
Together with the piezoelectric elements facing the detection electrodes 34A and 34B, they function as strain gauges. The voltage values of the detection signals from the detection electrodes 34A and 34B are proportional to the magnitude of the distortion. This detection electrode 34A,
The arrangement position of 34B will be described later.

The vibrating plate 10 having such a structure is provided with the piezoelectric elements 30 and 33 from the drive circuit 500 via the electrodes 33 and 33.
When an AC drive signal is applied to the piezoelectric element 31, the piezoelectric elements 30,
At 31, vibration that expands and contracts in the longitudinal direction is generated. At this time, as shown in FIG. 8, the piezoelectric element 30, 31 expands and contracts in the longitudinal direction, so that the diaphragm 10 generates longitudinal vibration that expands and contracts in the longitudinal direction. 4 vibrates in the direction indicated by the middle arrow. As described above, when the vibration plate 10 is electrically excited by the longitudinal vibration by the application of the drive signal to the piezoelectric elements 30 and 31, the vibration plate 1
Diaphragm 10 due to the unbalance of the weight balance of zero.
A rotation moment is generated about the center of gravity. As shown in FIG. 9, the bending moment induces a bending vibration in which the diaphragm 10 swings in the width direction (vertical direction in FIG. 4). In the present embodiment, in order to induce a larger bending vibration, the balance adjusting section 1 is attached to the end 16 of the diaphragm 10 opposite to the side where the contact section 36 is provided.
By providing 8, a larger rotational moment is generated.

As described above, longitudinal vibration and bending vibration are generated in the vibration plate 10, and the vibration vibration and the bending vibration are combined, so that the contact portion of the contact portion 36 of the vibration plate 10 with the rotor 100 is shown in FIG. Thus, it moves along an elliptical orbit. The contact portion 36 draws an elliptical trajectory, so that when the contact portion 36 is in a position swelling toward the rotor 100, the contact portion 36 comes into pressure contact with the rotor 100, while the contact portion 36 contacts the rotor 100. When is located at a position retracted from the rotor 100 side, the contact portion 36 is separated from the rotor 100 (or the pressing force is reduced even if the contact portion 36 is in contact with the rotor 100). Therefore, the piezoelectric actuator A drives the rotor 100 to rotate in the direction of displacement of the contact portion 36 while the pressing force of both is large, that is, when the contact portion 36 is on the rotor 100 side.

Here, as shown in FIG. 11, the balance adjusting section 18 defines a line extending in the vibration direction of the longitudinal vibration as a horizontal line W, and passes through a point serving as a node of the longitudinal vibration and is orthogonal to the vibration direction of the longitudinal vibration. And a portion of the diaphragm 10 that is located on the opposite side of the contact portion 36 when viewed from the horizontal line W is equal in weight to 2
A line dividing the two parts a and b is defined as a vertical line L, and the intersection point O where the vertical line L and the horizontal line W intersect is a point symmetrical position with the contact part 36 and the two parts a and b This is to make the weight different. The balance adjusting section 18 may have the same shape or the same weight as the contact section 36.

C2. Next, the impedance characteristics of a mechanical structure such as the diaphragm 10 will be described. When the force applied to a mechanical structure such as the diaphragm 10 is kept constant and the excitation frequency is gradually increased, the amplitude of the structure at a specific frequency becomes a maximum value (that is, the impedance has a minimum value). , And thereafter, a response of a minimum value (a maximum value of the impedance) is repeated. That is, there are a plurality of excitation frequencies whose amplitudes have a maximum value, and each such excitation frequency is called a resonance frequency.
The resonance frequency exists in each of the longitudinal vibration and the bending vibration, and in a rectangular structure such as the diaphragm 10, FIG.
Generally, it has a relationship between impedance and frequency as exemplified in FIG. In the illustrated example, the minimum value of the impedance of the longitudinal vibration of a predetermined order (for example, the first order) is fkHz.
Where the minimum value of the impedance of the bending vibration of a certain order (for example, the second order) is FkHz, and the minimum value of the impedance of both the vibrations is different (here, Δf = F−
f is desirably about f × 0.01, for example, f = 196 k
Hz, F = 196 kHz to 200 kHz).

The relationship between the resonance frequency of each vibration and the frequency of the applied drive signal is such that when the voltage value of the applied drive signal is constant, the amplitude of each vibration is such that the resonance frequency of each vibration is maximized. Is shifted from the resonance frequency,
The characteristics become gradually smaller. Further, since the bending vibration of the diaphragm 10 is induced by the gravitational imbalance at the time of the longitudinal vibration, the phase difference from the longitudinal vibration is shifted due to the magnitude of the amplitude of the longitudinal vibration and the like. That is, it has a characteristic that the difference between the phase of the longitudinal vibration and the phase of the bending vibration changes according to the frequency of the drive signal. In order to obtain the necessary drive, it is necessary to set the amplitude of each vibration and the phase difference to be excited. It depends on the frequency of the drive signal applied to the elements 30, 31. In the present embodiment, as shown in FIG.
Driving such that a frequency of a certain value fs between the resonance frequency of the primary longitudinal vibration and the resonance frequency of the secondary bending vibration is adopted as the frequency of the drive signal, and the drive signal of the frequency is supplied to the piezoelectric elements 30 and 31. Do.

C3. Next, the detection electrode will be described with reference to FIGS. FIG. 13 shows detection electrodes P1, P2, P3, and P4 arranged near four corners on the surface of diaphragm 10. FIGS. 14 and 15 show the results of experiments in which the voltage values of the detection signals detected from the detection electrodes P1 and P4 among the detection electrodes P1 to P4 are divided into a no-load state and a drive state. FIG. 14 shows a detection electrode P obtained when the frequency of the drive signal supplied to the piezoelectric elements 30 and 31 of the diaphragm 10 is changed in a no-load (free) state.
FIG. 3 is a diagram illustrating voltage values and impedances of detection signals detected from P1 and P4. FIG. 15 shows detection electrodes P1 and P4 obtained when the frequency of the drive signal supplied to the piezoelectric elements 30 and 31 of the diaphragm 10 is changed in the driving state.
FIG. 5 is a diagram showing a voltage value of a detection signal detected from the above, a difference signal indicating a difference voltage value, and a rotation speed of the rotor 100. 14 and 15, the characteristic line a is the detection electrode P1.
, A characteristic line b indicates a detection signal detected from the detection electrode P2, a characteristic line c indicates impedance, a characteristic line d indicates a rotor speed, and a characteristic line e indicates a difference signal.

Next, what is detected from FIGS. 14 and 15 will be described. As a premise, it is assumed that the diaphragm 10 performs substantially the same vibration (longitudinal vibration, bending vibration) regardless of the driving conditions (pressing force, driving torque, etc.) regardless of the no-load state and the driving state. When the rotor 100 is not driven (free state),
As for the voltage values (characteristic lines a and b) of the detection signals obtained from the detection electrodes P1 and P4, the detection signals near the resonance point of the longitudinal vibration become maximum. The voltage value (characteristic lines a and b) of the detection signal and the number of rotations of the rotor (characteristic line d) when the rotor is driven (drive signal input of a constant voltage value)
Therefore, the detection signals from the detection electrodes P1 and P4 are different when the rotor is driven. This is because the detection voltage P1 is distorted by the reaction that the diaphragm 10 receives from the rotor 100 when the rotor is driven.
It is considered that the voltage is generated by the piezoelectric effect of the piezoelectric element at the position of the detection electrode P1 due to both the action and the distortion caused by the reaction. The maximum of the voltage value of the detection signal of the detection electrode P1 and the rotor 1
The rotation speed (characteristic line d) of 00 substantially coincides with the maximum. The maximum of the voltage value (characteristic line e) obtained by subtracting the voltage value of the detection electrode P2 from the voltage value of the detection electrode P1 substantially coincides with the maximum of the rotor speed (characteristic line d). From this, it is considered that the voltage component generated by the longitudinal vibration is canceled by subtracting the voltage value of the detection electrode P4 from the voltage value of the detection electrode P1. For this reason, the difference signal is regarded as detecting an approximate distortion when the rotor is driven. This is the diaphragm 10
It shows how the force was transferred from the rotor to the rotor 100, and has a close relationship with the driving force and the rotation speed of the rotor.

Arrangement Position of Detection Electrodes When Detection is Performed Using Two Electrodes When the rotor 100 is not driven, the same vibration occurs, and only one electrode is driven when the rotor 100 is driven.
What is necessary is just to provide in the position which is easy to receive the reaction force from. That is, the detection electrodes P2 and P3 may be used. When detecting using one electrode 1) Voltage value detected by distortion due to reaction force from rotor 100 divided by distortion inherent to diaphragm (first-order longitudinal vibration and second-order bending vibration in the embodiment) This is provided at a position where a voltage value generated by the above operation is obtained (the detection electrode 34C in FIG. 21 and the detection electrode 34E in FIG. 23). 2) An electrode is provided at a position in the detection electrode where a voltage value generated due to distortion due to vibration inherent in the diaphragm is canceled out and only a detection signal generated due to distortion due to a reaction from the rotor 100 can be detected (see FIG. 22). Detection electrode 34D). 3) An electrode is provided at a position that is a node of vibration and can detect a detection signal generated by distortion due to a reaction from the rotor 100.

D. Configuration of Driving Circuit The driving circuit 500 is divided into a circuit using two detection signals and a circuit using one detection signal. D1.2 Drive Circuit Using Two Detection Signals As shown in FIG. 16, the drive circuit includes a detection electrode 34 disposed near the contact portion 36 on the surface of the diaphragm 10.
A and a detection electrode 34 arranged near the balance portion 18
B is used. The detection electrodes 34A and 34B correspond to the detection electrodes P1 and P4 (FIG. 12) described above.

D1-1. Configuration of Drive Circuit 500A Next, the drive circuit 500A will be described with reference to FIG. The drive circuit 500A includes a subtraction circuit 501, a delay circuit 502, a comparison circuit 503, and a voltage adjustment circuit 50.
4 and a Voltage Controlled Oscilla
(tor: VCO) 505 and a driver circuit 506. The detection signal Va is detected from the detection electrode 34A, and the detection signal Vb is detected from the detection electrode 34B.
Is detected. The subtraction circuit 501 is a circuit that calculates the difference between the detection signal Va detected by the detection electrode 34A and the detection signal Vb detected by the detection electrode 34B.
To the delay circuit 502 and the comparison circuit 503. At this time, the voltage value of the difference signal Vc is Vc = | Va-Vb |. Further, the subtraction circuit 501 may be constituted by a bridge circuit. The delay circuit 502 outputs the difference signal Vc
Is delayed by a predetermined time tp and output to the comparison circuit 503 as a delay signal Vd.

The comparison circuit 503 compares the voltage value of the difference signal Vc with the voltage value of the delay signal Vd.
If ≧ delay signal Vd, a comparison result signal Ve that becomes “H” is output to voltage adjustment circuit 504, and if difference signal Vc <delay signal Vd, comparison result signal Ve that becomes “L” is applied to voltage Output to the adjustment circuit 504. Voltage adjustment circuit 504
Is for changing the voltage value of the adjustment signal Vf output to the VCO 505 in response to the comparison result signal Ve in units of a predetermined voltage value Vf0. That is, the voltage adjustment circuit 504 outputs “H”
When the comparison result signal Ve is received, the voltage value of the adjustment signal Vf is increased by a predetermined voltage value Vf0. When the comparison result signal Ve of “L” is received, the voltage value of the adjustment signal Vf is increased by the predetermined voltage value Vf0. Lower it. The voltage adjustment circuit 504 stores an initial value Vf1, and outputs an adjustment signal Vf having the initial value Vf1 as a voltage value to the VCO 505 at the time of startup.

The VCO (voltage controlled oscillation circuit) 505 receives the adjustment signal Vf and adjusts the frequency of the reference signal Vg output to the driver circuit 506. That is, V
When the voltage value of the adjustment signal Vf becomes higher than the voltage value of the previous adjustment signal Vf, the CO 505 increases the frequency of the reference signal Vg by a predetermined value f0, and the voltage value of the adjustment signal Vf becomes higher than the voltage value of the previous adjustment signal Vf. When the voltage becomes lower than the voltage value, the frequency of the reference signal Vg is adjusted so as to be lowered by a predetermined value f0. When the VCO 505 receives the adjustment signal Vf of the initial value Vf1 at the time of startup, the VCO 505
Output g. This frequency is, for example, a frequency fsta (about 284.0 kHz). Driver circuit 506 receives reference signal Vg, and outputs drive signal Vh having a constant voltage value at the frequency of reference signal Vg toward electrode 33 of diaphragm 10. The driving signal Vh is applied to the diaphragm 1
0 is supplied to the piezoelectric elements 30 and 31.

D1-2. Operation of Drive Circuit 500A Next, the operation of the drive circuit 500A will be described with reference to the flowchart of FIG. First, the driving circuit 500A
Are activated by supplying a power supply (not shown). When the power is turned on, the voltage adjustment circuit 504 adjusts the adjustment signal Vf of the preset initial value Vf1.
Is output to the VCO 505 (step Sa1).
The VCO 505 receives the adjustment signal Vf, and outputs a reference signal Vg having a frequency fs corresponding to the initial value Vf1 to the driver circuit 506.
(Step Sa2). Driver circuit 506
Receives the reference signal Vg of the frequency fs and outputs the drive signal Vh of the frequency fsta to the electrodes 33 of the diaphragm 10 (step Sa3). Then, the piezoelectric element 3 of the diaphragm 10
0, 31 are the drive signals Vh supplied via the electrodes 33
Then, as described above, longitudinal vibration and bending vibration are generated (step Sa4).

Next, the subtraction circuit 501 is connected to the detection electrode 34.
The detection signals Va and Vb are read from A and 34B (step Sa5), the difference signal Vc is calculated by the following equation (1), and output to the delay circuit 502 and the comparison circuit 503 (step Sa6). Vc = | Va−Vb | (1) The delay circuit 502 receives the difference signal Vc, and receives a predetermined time (tp
The delay signal Vd is output to the comparison circuit 503 (step Sa7). The comparison circuit 503 outputs the difference signal V
The voltage value of c and the voltage value of the delay signal Vd are compared (step Sa8). In the comparison in step Sa8, when the voltage value of the difference signal Vc is equal to or more than the voltage value of the delay signal Vd, that is, when Vc ≧ Vd (2) (step Sa8; YES), the comparison circuit 503 determines , Output the comparison result signal Ve at the “H” level to the voltage adjustment circuit 504 (step Sa9). On the other hand, when the voltage value of the difference signal Vc is smaller than the voltage value of the delay signal Vd in the comparison in step Sa8, that is, when Vc <Vd (3) (step Sa8; NO), the comparison is made. Circuit 5
03 outputs the "L" level comparison result signal Ve to the voltage adjustment circuit 504 (step Sa10).

As a result, the voltage adjusting circuit 504 receives the comparison result signal Ve, and sets the comparison result signal Ve to “H”.
In the case of the level, a reference signal Vf having a voltage value obtained by adding a predetermined voltage value Vf0 to the voltage value of the reference signal Vf is generated and output to the VCO 505. On the other hand, the comparison result signal Ve
Is "L" level, the reference signal V having a voltage value obtained by subtracting a predetermined voltage value Vf0 from the voltage value of the reference signal Vf.
f is generated and output to the VCO 505 (step Sa1).
1). The voltage adjustment circuit 504 again outputs the adjustment signal Vf to the VCO
Then, the VCO 505 outputs the reference signal Vg whose frequency has been changed in response to the adjustment signal Vf to the driver circuit 506 (step Sa2).
6 receives the frequency reference signal Vg and outputs the drive signal Vh of the changed frequency f to the electrodes 33 of the diaphragm 10 (step Sa3). Thus, the frequency of the drive signal Vh is sequentially changed according to the detected distortion of the diaphragm 10.

Next, FIGS. 19 and 20 show drive signals V
An operation situation until the frequency f of h becomes constant will be described. 19 shows a frequency characteristic of the difference signal Vc and the number of rotations N of the rotor, and FIG. 20 shows a timing chart of the operation. Here, the frequency of the drive signal Vh at the time of starting is fst
a, Let fs be the frequency of the drive signal Vh when the number of revolutions is at a maximum. As is clear from FIG. 19, the difference signal Vc
And the rotation speed N draw substantially the same curve, and it can be seen that the maximum value of the difference signal Vc and the maximum value of the rotation speed N occur near the same frequency fs. When the drive circuit 500A is activated, the diaphragm 10 is distorted as shown in FIG.
By setting the initial value of d to be lower than the minimum value of the difference signal Vc (for example, the difference signal when there is no distortion), the difference signal Vc becomes equal to or longer than the delay signal Vd, so that the reference signal output from the VCO 505 is obtained. The frequency f of Vg increases. After that, the frequency f of the reference signal Vg gradually increases to maintain the relationship of the difference signal Vc ≧ the delay signal. And
When the frequency f of the drive signal Vh exceeds fs, that is, when the difference signal Vc <the delay signal Vd, the VCO 50
The frequency f of the reference signal Vg output from 5 is lowered. As a result, the frequency of the drive signal Vh is set to a substantially constant frequency f.
s.

D2.1 Driving Circuit Using One Detection Signal As shown in FIG. 21, this driving circuit includes a detecting electrode 34 disposed near the contact portion 36 on the surface of the diaphragm 10.
The diaphragm 10 provided with C is used. This detection electrode 3
4C corresponds to the detection electrode P1 in FIG. 12, and outputs a detection signal Va. Since the detection electrode 34C detects distortion when the diaphragm 10 comes into contact with the rotor 100, the detection electrode 34D is provided on the diaphragm 10 as shown in FIG. 22, and is provided as shown in FIG. The detection electrode 34 </ b> E may be used as long as it detects distortion caused by a load between the support member 11 and the contact portion 36.

D2-1. Configuration of Drive Circuit 500B Next, the drive circuit 500B will be described with reference to FIG. The drive circuit 500B includes a peak hold circuit 5
07, the delay circuit 502, the comparison circuit 503, the voltage adjustment circuit 504, and the voltage control oscillation circuit (Voltage Control Oscillator).
ed Oscillator (VCO) 505 and driver circuit 50
6 is provided. Here, the configuration other than the peak hold circuit 507 is the same as the configuration of the above-described drive circuit 500A, and thus the description thereof is omitted. The peak hold circuit 507 outputs a peak signal Vp, which holds the peak value of the voltage value of the detection signal Va detected by the detection electrode 34C, to the delay circuit 502 and the comparison circuit 503. The delay circuit 502 delays the peak signal Vp by a predetermined time tp to delay the peak signal Vp.
Is output to the comparison circuit 503.

D2-2. Operation of Drive Circuit 500B Next, the operation of the drive circuit 500B will be described based on the flowchart of FIG. First, the driving circuit 500B
Is activated by turning on a power supply (not shown). When the power is supplied, the voltage adjustment circuit 504 adjusts the adjustment signal Vf of the preset initial value Vf1.
Is output to the VCO 505 (step Sb1).
The VCO 505 receives the adjustment signal Vf, and outputs a reference signal Vg having a frequency fs corresponding to the initial value Vf1 to the driver circuit 506.
(Step Sb2). Driver circuit 506
Receives the reference signal Vg of the frequency fs and outputs the drive signal Vh of the frequency fsta to the electrodes 33 of the diaphragm 10 (step Sb3). Then, the piezoelectric element 3 of the diaphragm 10
0, 31 are the drive signals Vh supplied via the electrodes 33
Then, as described above, longitudinal vibration and bending vibration are generated (step Sb4).

Next, the peak hold circuit 507 reads the detection signal Va from the detection electrode 34C (step Sb).
5) The peak value of the voltage value of the detection signal Va is output as the peak signal Vp (step Sb6). Delay circuit 5
02 receives the peak signal Vp and outputs a delay signal Vq delayed by a predetermined time (tp seconds) to the comparison circuit 503 (step Sb7). The comparison circuit 503 detects the peak signal V
The voltage value of p and the voltage value of the delay signal Vq are compared (step Sb8). In the comparison in step Sb8, when the voltage value of the peak signal Vp is equal to or more than the voltage value of the delay signal Vq,
That is, if Vp ≧ Vq (4) (step Sb8; YES), the comparison circuit 503 outputs an “H” level comparison result signal Ve to the voltage adjustment circuit 504 (step Sb9). On the other hand, when the voltage value of the peak signal Vp is smaller than the voltage value of the delay signal Vq in the comparison in step Sb8, that is, when Vp <Vq (5) (step Sb8; NO), the comparison is performed. Circuit 5
03 outputs the “L” level comparison result signal Ve to the voltage adjustment circuit 504 (step Sb10).

As a result, the voltage adjusting circuit 504 receives the comparison result signal Ve, and sets the comparison result signal Ve to “H”.
In the case of the level, a reference signal Vf having a voltage value obtained by adding a predetermined voltage value Vf0 to the voltage value of the reference signal Vf is generated and output to the VCO 505. On the other hand, the comparison result signal Ve
Is "L" level, the reference signal V having a voltage value obtained by subtracting a predetermined voltage value Vf0 from the voltage value of the reference signal Vf.
f is generated and output to the VCO 505 (step Sb1).
1). The voltage adjustment circuit 504 again outputs the adjustment signal Vf to the VCO
505, and the VCO 505 receives the adjustment signal Vf, and outputs the reference signal Vg whose frequency corresponding to the voltage value has been changed to the driver circuit 506 (step Sb).
2) The driver circuit 506 receives the frequency reference signal Vg, and supplies the driving signal Vh having the changed frequency f to the diaphragm 10.
(Step Sa3). As a result, the frequency of the drive signal Vh is
It is sequentially changed according to the distortion of 0.

D3.1 Other driving circuit using one detection signal D3-1. Configuration of Drive Circuit 500C Next, the drive circuit 500C will be described with reference to FIG. The drive circuit 500C includes a phase difference-voltage conversion circuit 508, a constant voltage circuit 509, a comparison circuit 503, a voltage adjustment circuit 504, and a voltage control oscillation circuit (Voltage Control Oscillator).
A rolled oscillator (VCO) 505 and a driver circuit 506 are provided. Here, the phase difference −
Except for the voltage conversion circuit 508 and the constant voltage circuit 509, the configuration is the same as that of the above-described drive circuit 500A, and a description thereof will be omitted. Phase difference-voltage conversion circuit 50
8 detects a phase difference between the phase of the detection signal Va detected from the detection electrode 53C and the phase of the drive signal Vh, and compares the phase difference voltage signal Vj having a voltage value corresponding to the average phase difference with the comparison circuit 503. Output to Here, a schematic configuration of the phase difference-voltage conversion circuit 508 will be described with reference to FIG. The phase difference-voltage conversion circuit 508 is roughly divided into a phase difference detection section 508A and an average voltage conversion section 508B. The phase difference detector 508A receives the detection signal Va and the drive signal Vh, generates a phase difference signal Vpd having a pulse width corresponding to the phase difference between the two signals, and outputs the average voltage converter 5d.
08B. FIG. 28 shows a case where the phase difference between the detection signal Va and the drive signal Vh is small (phase difference = Δφ1)
Here is an example. When the waveforms of the detection signal Va and the drive signal Vh are as shown in FIG. 28A, the pulse width of the phase difference signal Vpd corresponding to the detected phase difference is as shown in FIG.
It becomes Δφ1 as shown in FIG. Therefore, the average voltage conversion unit 508B generates a phase difference voltage signal Vj having an average voltage value Vav1 corresponding to the pulse width Δφ1 of the phase difference signal Vpd by an integrating circuit (not shown), and outputs the same to the comparison circuit 503.

FIG. 29 shows a case where the phase difference between detection signal Va and drive signal Vh is large (when phase difference = Δφ2).
Here is an example. When the waveforms of the detection signal Va and the drive signal Vh are as shown in FIG. 29A, the pulse width of the phase difference signal Vpd corresponding to the detected phase difference is
It becomes Δφ2 as shown in FIG. Therefore, the average voltage converter 508B generates a phase difference voltage signal Vj having an average voltage value Vav2 corresponding to the pulse width Δφ2 of the phase difference signal Vpd by an integrating circuit (not shown), and outputs the same to the comparison circuit 503.

The constant voltage circuit 509 outputs to the comparison circuit 503 a reference phase difference signal Vk having a voltage value corresponding to an optimum phase difference between the phase of the detection signal Va and the phase of the drive signal Vh obtained in advance. Is what you do.

D3-2. Operation of Drive Circuit 500C Next, the operation of the drive circuit 500C will be described with reference to the flowchart in FIG. First, the drive circuit 500C
Is activated by turning on a power supply (not shown). When the power is supplied, the voltage adjustment circuit 504 adjusts the adjustment signal Vf of the preset initial value Vf1.
Is output to the VCO 505 (step Sc1).
The VCO 505 receives the adjustment signal Vf, and outputs a reference signal Vg having a frequency fs corresponding to the initial value Vf1 to the driver circuit 506.
(Step Sc2). Driver circuit 506
Receives the reference signal Vg of the frequency fs and outputs the drive signal Vh of the frequency fsta to the electrodes 33 of the diaphragm 10 (step Sc3). Then, the piezoelectric element 3 of the diaphragm 10
0, 31 are the drive signals Vh supplied via the electrodes 33
Then, as described above, longitudinal vibration and bending vibration are generated (Step Sc4).

Next, the phase difference-voltage conversion circuit 508 reads the detection signal Va and the drive signal Vh from the detection electrode 34C (Step Sc5), and determines the phase difference between the phase of the detection signal Va and the phase of the drive signal Vh. The phase difference voltage signal Vj is generated by the processing as described above and output to the comparison circuit (step Sc6). The comparison circuit 503 compares the voltage value of the phase difference voltage signal Vj with the voltage value of the reference phase difference signal Vk output from the constant voltage circuit 509 (Step Sc7). If the voltage value of the phase difference voltage signal Vj is equal to or higher than the voltage value of the reference phase difference signal Vk in the comparison in step Sc8, that is, if Vj ≧ Vk (6) (step Sc8; YES), The comparison circuit 503 outputs the "H" level comparison result signal Ve to the voltage adjustment circuit 504 (Step Sc8). On the other hand, in the comparison in step Sc8, when the voltage value of the phase difference voltage signal Vj is smaller than the voltage value of the reference phase difference signal Vk, that is, when Vj <Vk (7) (step Sc8; NO), comparison circuit 5
03 outputs the "L" level comparison result signal Ve to the voltage adjustment circuit 504 (step Sc9).

As a result, the voltage adjustment circuit 504 receives the comparison result signal Ve and changes the comparison result signal Ve to "H".
In the case of the level, a reference signal Vf having a voltage value obtained by adding a predetermined voltage value Vf0 to the voltage value of the reference signal Vf is generated and output to the VCO 505. On the other hand, the comparison result signal Ve
Is "L" level, the reference signal V having a voltage value obtained by subtracting a predetermined voltage value Vf0 from the voltage value of the reference signal Vf.
f is generated and output to the VCO 505 (step Sc1).
0). The voltage adjustment circuit 504 again outputs the adjustment signal Vf to the VCO
505, and the VCO 505 receives the adjustment signal Vf, and outputs the reference signal Vg whose frequency corresponding to the voltage value has been changed to the driver circuit 506 (step Sc).
2) The driver circuit 506 receives the frequency reference signal Vg, and supplies the driving signal Vh having the changed frequency f to the diaphragm 10.
(Step Sc3). As a result, the frequency of the drive signal Vh is
It is sequentially changed according to the distortion of 0.

[0076] E. Operation of Calendar Display Mechanism Next, a driving circuit 500 for driving the piezoelectric actuator A
Will be described with reference to FIG. Note that the driving circuit 500 includes the driving circuits 500A,
00B or 500C. As shown in FIG.
01 and a date feed detecting means 602 are provided. The midnight detection means 601 is a mechanical switch incorporated in the movement 73 (see FIG. 2), and outputs a control signal to the drive circuit 500 at midnight. The date feed detecting means 602 includes the above-described leaf spring 64 and the contact 65 (see FIG. 1) as main parts. When the leaf spring 64 and the contact 65 come into contact with each other, that is, when the end of date feed is detected. The control signal is output to the drive circuit 500.

The drive circuit 500 includes the midnight detection means 60.
Driving is started based on the control signal supplied from 1 and the control signal supplied from the date feed detecting means 602.
Thus, as described above, the drive circuit 500 starts operating, and vibrates the diaphragm 10 to rotate the rotor 100. The daily turning intermediate wheel 40 makes one rotation per day, but the period is a limited time starting from midnight. Therefore, it is sufficient that the drive circuit 500 oscillates only during the period. In the drive circuit 500 of this example,
By setting all the constituent circuits of the drive circuit 500 to the non-operation state by the drive control signal, the operation of the drive circuit 500 is completely stopped during the period in which the date intermediate wheel 40 does not need to be turned. Therefore, power consumption of the driving circuit 500 can be reduced.

Next, the automatic updating operation of the calendar display mechanism provided with the piezoelectric actuator A having the above-described structure will be described with reference to FIGS.
This will be described with reference to FIGS. 3, 4 and 31. At midnight on each day, the midnight detection means 601 detects that it is midnight, and the driving circuit 500
Is started. As a result, the drive signal Vh of the frequency at which the rotor rotation speed substantially coincides with the resonance frequency of the longitudinal vibration is maximized from the drive circuit 500 and the piezoelectric elements 30 and 3 of the diaphragm 10 are driven.
1 is supplied via electrodes 33, 33.

When the drive signal Vh from the drive circuit 500 is applied to the electrodes 33, 33, the piezoelectric elements 30, 31 flex and vibrate due to expansion and contraction, and the diaphragm 10 vibrates longitudinally. At this time, when the polarization directions of the piezoelectric elements 30 and 31 are set to be the same as described above, the potentials of the upper surface, the center, and the lower surface are + V, 0, and -V (or -V, 0, and + V), respectively. A voltage is applied so that When the polarization directions of the piezoelectric elements 30 and 31 are opposite, a voltage is applied so that the potentials of the upper surface, the center, and the lower surface are + V, 0, + V (or -V, 0, -V), respectively ( (See FIG. 7). And the diaphragm 10
Is electrically excited in the vertical direction, bending vibration is induced mechanically by the imbalance of the weight balance of the diaphragm 10. Then, by combining the longitudinal vibration and the bending vibration, the contact portion 36 is displaced along the elliptical orbit, and drives the rotor 100.

When the piezoelectric actuator A is driven by the driving circuit 500 in this manner, the rotor 100
Rotates in the clockwise direction in FIG. 4, and accordingly, the date turning intermediate wheel 40 starts rotating in the counterclockwise direction.

Here, the drive circuit 500 is configured to stop supplying the drive signal when the leaf spring 64 and the contact 65 shown in FIG. 1 come into contact with each other. Leaf spring 64 and contact 6
In a state where the contact portion 5 is in contact with the front end portion 5, the front end portion 64a enters the cutout portion 4c. Accordingly, the date intermediate wheel 40 starts rotating from such a state.

Since the date driving wheel 60 is urged clockwise by the leaf spring 63, the small diameter portion 4a is
It rotates while sliding on the zero teeth 6a, 6b. When the notch 4c reaches the position of the tooth 6a of the date wheel 60 on the way, the tooth 6a meshes with the notch 4c.

Next, when the date turning intermediate wheel 40 continues to rotate counterclockwise, the date driving wheel 60 is rotated.
In conjunction with 0, it rotates clockwise by one tooth, that is, "1/5" circumference. Further, in conjunction with this, the date wheel 50 is rotated clockwise by one tooth (corresponding to a date range for one day). On the last day of the month in which the number of days in the month is less than "31", the above operation is repeated a plurality of times, and the correct date based on the calendar is displayed by the date indicator 50.

When the date intermediate wheel 40 continues to rotate counterclockwise and the notch 4c reaches the position of the tip 64a of the leaf spring 64, the tip 64a is moved to the notch 4c.
Get into it. Then, the leaf spring 64 and the contact 65 come into contact with each other, the supply of the drive signal ends, and the rotation of the date intermediate wheel 40 stops. Therefore, the date intermediate wheel 40 is operated once a day.
Will rotate.

F. Effects of this embodiment As described above, in this embodiment, the calendar display mechanism can be driven with high efficiency using the thin piezoelectric actuator A that can be installed in a limited space such as a wristwatch. The drive circuit 500 for driving the piezoelectric actuator A detects the distortion of the diaphragm 10, detects the vibration state of the diaphragm 10 from the distortion, and controls the frequency of the drive signal Vh so as to always maintain the same vibration state. Thus, it is possible to always drive the rotor 100 that rotates with the vibration of the diaphragm at an optimum rotation speed. Thereby, the conversion efficiency of converting the electric energy of the drive signal Vh supplied to the diaphragm 10 into the mechanical energy (rotation) of the rotor 100 can be increased, and an efficient piezoelectric actuator A can be realized. Become. As a result,
The piezoelectric actuator A can perform stable drive control.

F. Modifications The present invention is not limited to the above embodiment, and various modifications as exemplified below are possible.

(Modification 1) In the above-described embodiment, the case where the piezoelectric actuator A and the drive circuit 500 are employed as a drive source of a calendar display mechanism mounted on a wristwatch has been described as an example. The present invention is not limited to this, and can be applied to other types of devices, for example, a driving mechanism of an amusement device such as a toy or a driving mechanism of a small blower. Further, as described above, the piezoelectric actuator A can be made thinner and smaller, and can be driven with high efficiency. Therefore, the piezoelectric actuator A is suitable as an actuator mounted on a battery-driven portable device or the like.

As a specific example, it is conceivable to employ the piezoelectric actuator A and the drive circuit 500 in a non-contact type IC card having a settlement function. FIG. 32 shows an external perspective view of a non-contact type IC card. On the front side of the non-contact type IC card 400, a balance display counter 401 for displaying the balance is provided. The balance display counter is 401
Displays a four-digit balance, and includes, as shown in FIG. 33, an upper digit display unit 402 for displaying the upper two digits and a lower digit display unit 403 for displaying the lower two digits. .

FIG. 34 is a detailed configuration side view of the upper digit display section 402. The upper digit display section 402 is connected to the piezoelectric actuator A1 via the rotor 100A, and is driven by the driving force of the rotor 100A. The main part of the upper digit display section 402 has a feed claw 402A and has a rotor 100
A drive gear 402A that makes one rotation when A rotates 1 / n;
A first upper digit display wheel 402B that rotates by one division with one rotation of the drive gear 402A, a second upper digit display wheel 402C that rotates by one division with one rotation of the first upper digit display wheel 402B, and a first upper digit And a fixing member 402D for fixing the first upper digit display wheel 402B when the display wheel 402B is not rotating. Note that a fixing member (not shown) for fixing the second upper digit display wheel 402C is also provided for the second upper digit display wheel 402B.

The driving gear 402A has the rotor 100A
/ N rotations make one rotation. And the feed claw 402A is
The first upper-digit display wheel 402B is engaged with the feed gear portion 402B3 of the first upper-digit display wheel 402B, so that the first upper-digit display wheel 402B rotates by one scale. Further, when the first upper digit display wheel 402B rotates and makes one revolution, the feed pin 402B provided on the first upper digit display wheel 402B rotates the feed gear 402B2, and the second gear in which the feed gear 402B meshes. The feed gear 402C of the upper digit display wheel 402C is rotated, and the second upper digit display wheel 402C is rotated by one scale.
The lower digit display unit 403 is connected to the piezoelectric actuator A2 via the rotor 100B, and is driven by the driving force of the rotor 100B. The main part of the lower digit display section 403 has a feed claw 403A1 and the rotor 100B is 1 / n.
A drive gear 403A that rotates once when rotated, and a drive gear 4
The first lower digit display wheel 4 that rotates by one division in one rotation of 03A
03B, and a second lower digit display wheel 403C that rotates by one division with one rotation of the first lower digit display wheel 403B.

FIG. 35 is a front view of the detailed configuration of the lower digit display section 403, and FIG. 36 is a side view of the detailed configuration. First
The lower digit display wheel 403B is provided with the feed pawl 4 of the drive gear 403A.
It has a feed gear portion 403B1 that meshes with 03A1, and rotates by one graduation with one rotation of the drive gear 403A. Then, the feed pin 403 is provided on the first lower digit display wheel 403B.
B2 is provided, and the first lower digit display wheel 403B is 1
The feed gear 403B is rotated every time it rotates.
The lower digit display wheel 403C is rotated by one scale. In this case, the fixing member 403 of the first lower-digit display wheel 403B is used.
D meshes with the feed gear portion 403B1 during non-rotation and
The lower digit display wheel 403B is fixed. Further, the fixing member 403E of the second lower digit display wheel 403C meshes with the feed gear portion 403F when the second lower digit display wheel 403C is not rotating, and fixes the second lower digit display wheel 403C. In this case, the actuator A1 and the actuator A2 are
The drive circuit 200B is set to be driven in synchronization with the drive circuit 200B, and is driven by input of a drive control signal corresponding to a payment amount by an IC card chip (not shown).

With the above configuration, even in a thin device such as a non-contact IC card, the remaining amount can be displayed mechanically, and the display can be performed without a power source except during driving. Therefore, the display can be performed with low commercial power, and the display can be maintained even when the power supply is lost.

(Modification 2) As a power source of the piezoelectric actuator, in addition to batteries (primary batteries and secondary batteries), a solar battery, a thermoelectric generator, a mechanical generator, and a power storage device (capacitor or secondary battery) are provided. It is also possible to use a power supply with a built-in power generation mechanism.

(Modification 3) In the above embodiment, the case where the vibration plate 10 vibrates to rotate the rotor 100 which is in contact with the contact portion 36 has been exemplified. However, the present invention is not limited to this, and can be applied to a linear actuator that drives a drive target in a straight line.

(Modification 4) In the above-described embodiment, the rectangular diaphragm 10 is used. However, the shape of the diaphragm 10 is not limited to a rectangular shape, but may be a shape having a longitudinal direction. Any shape may be used as long as it has a trapezoidal shape, a parallelogram shape, a rhombus shape, a triangular shape, or the like.

(Modification 5) In the above-described embodiment, the strain detecting section is constituted by the detecting electrode and the portion of the piezoelectric element where this electrode is located. However, the present invention is not limited to this. A plate-like piezoelectric element may be attached to the diaphragm to be used as a piezoelectric sensor.

[0097]

As described above, according to the present invention,
Since the distortion of the diaphragm is detected and the frequency of the drive signal is controlled so that the diaphragm always vibrates at the maximum from the distortion, it is possible to always drive the drive target with an optimal operation. . Further, high efficiency and stable driving can be performed while having a configuration that can be reduced in size and thickness.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a main part of a calendar display mechanism in a wristwatch according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a schematic configuration of the wristwatch.

FIG. 3 is a sectional view showing a main part of the calendar display mechanism.

FIG. 4 is a plan view showing a configuration of a piezoelectric actuator which is a component of the calendar display mechanism.

FIG. 5 is a sectional view showing a diaphragm which is a component of the piezoelectric actuator.

FIG. 6 is a diagram showing an electrode portion formed on a surface of a piezoelectric element of the vibration plate.

FIG. 7 is a diagram showing a schematic drive configuration when a voltage is applied to a piezoelectric element of the diaphragm.

FIG. 8 is a view schematically showing a state in which the diaphragm vibrates longitudinally.

FIG. 9 is a view schematically showing a state in which the diaphragm undergoes bending vibration.

FIG. 10 is a view for explaining the trajectory of the contact portion when the diaphragm vibrates.

FIG. 11 is a diagram showing an arrangement position of an unbalance adjustment unit.

FIG. 12 is a graph showing an example of a relationship between a vibration frequency of the diaphragm and impedance.

FIG. 13 is a plan view showing an arrangement position of detection electrodes provided at four corners of the diaphragm.

FIG. 14 is a characteristic diagram showing a voltage value and an impedance of a detection signal obtained when the diaphragm is driven in a no-load state.

FIG. 15 is a characteristic diagram showing a voltage value, an impedance, and a rotor speed of a detection signal obtained when the diaphragm is driven in a driving state.

FIG. 16 is a plan view showing an arrangement position of a detection electrode provided on the diaphragm.

FIG. 17 is a block diagram illustrating a configuration of a drive circuit used in the present embodiment.

FIG. 18 is a flowchart showing the operation of the driving circuit.

FIG. 19 is a characteristic diagram illustrating frequency characteristics of a difference signal Vc and a rotation speed N of a rotor.

FIG. 20 shows a difference signal Vc, a delay signal Vd, and a drive signal Vh.
6 is a timing chart showing the frequency of the data.

FIG. 21 is a plan view showing an arrangement position of another detection electrode provided on the diaphragm.

FIG. 22 is a plan view showing an arrangement position of another detection electrode provided on the diaphragm.

FIG. 23 is a plan view showing an arrangement position of another detection electrode provided on the diaphragm.

FIG. 24 is a block diagram illustrating a configuration of another drive circuit used in the present embodiment.

FIG. 25 is a flowchart showing the operation of the driving circuit.

FIG. 26 is a block diagram illustrating a configuration of another drive circuit used in the present embodiment.

FIG. 27 is a block diagram illustrating a configuration of a phase difference-voltage conversion circuit.

FIG. 28 is a diagram showing a waveform when the phase difference in the phase difference-voltage conversion circuit is small.

FIG. 29 is a diagram showing waveforms when the phase difference in the phase difference-voltage conversion circuit is large.

FIG. 30 is a flowchart showing the operation of the driving circuit.

FIG. 31 is a block diagram when a piezoelectric actuator and a drive circuit are used in a calendar display mechanism.

FIG. 32 is an explanatory diagram of a configuration of a balance display counter.

FIG. 33 is a front view showing a detailed configuration of an upper digit display unit.

FIG. 34 is a detailed configuration side view of the upper digit display unit.

FIG. 35 is a detailed configuration front view of a lower digit display section.

FIG. 36 is a detailed configuration side view of a lower digit display unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Vibration plate 11 ... Support member 30, 31 ... Piezoelectric element 33 ... Electrode 34A, 34B, 34C, 34D, 34E ... Detection electrode 36 ... Contact part 100 ... -Rotor 500, 500A, 500B, 500C ... drive circuit 501 ... subtraction circuit 502 ... delay circuit 503 ... comparison circuit 504 ... voltage adjustment circuit 505 ... voltage control oscillation circuit (VCO) 506: driver circuit 507: peak hold circuit 508: phase difference-voltage conversion circuit 509: constant voltage circuit A: piezoelectric actuator

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akihiro Sawada 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation F-term (reference) 2F082 AA00 BB02 DD01 DD10 EE02 EE03 EE05 EE06 FF01 5H680 AA06 AA19 BB02 BB20 BC02 BC04 CC02 DD11 DD15 DD23 DD27 DD34 DD46 DD65 DD73 DD83 DD95 DD98 EE10 EE12 EE20 EE24 FF26 FF30 FF32 GG02 GG43

Claims (19)

[Claims] 1. A vibration plate having at least one piezoelectric element that generates a longitudinal vibration and a bending vibration that vibrates in a direction substantially orthogonal to the longitudinal vibration when a drive signal is supplied, and provided on the diaphragm. A piezoelectric actuator that drives the object to be driven by displacement of the abutting part accompanying the longitudinal vibration and the bending vibration, wherein the vibration plate A piezoelectric actuator, further comprising: a distortion detecting unit that detects distortion of the diaphragm when driving the driving target. 2. The piezoelectric actuator according to claim 1, wherein a line extending in the direction of the longitudinal vibration is defined as a horizontal line, and extends in a direction perpendicular to the horizontal line through a point serving as a node of the vertical vibration. A line that divides a portion located on the opposite side of the abutting portion as viewed from the horizontal line into two portions having the same weight is defined as a vertical line, and an intersection of the vertical line and the horizontal line is defined as A piezoelectric actuator, characterized in that a balance adjusting part is provided at at least one of the parts at a point symmetrical position with respect to the contact part and for giving a difference in weight between the two parts. 3. The piezoelectric actuator according to claim 1, wherein a supporting member is provided on the vibration plate at a portion serving as a node of the longitudinal vibration. 4. The piezoelectric actuator according to claim 1, wherein the strain detecting section is viewed from a horizontal line extending through a portion of the vibration plate that becomes a node of the longitudinal vibration and extending in a direction orthogonal to the vibration direction of the longitudinal vibration. A piezoelectric actuator disposed on the contact portion side. 5. The piezoelectric actuator according to claim 1, wherein the strain detecting section is viewed from a horizontal line passing through a portion of the vibration plate that serves as a node of the longitudinal vibration and extending in a direction orthogonal to the vibration direction of the longitudinal vibration. A first detecting portion disposed on the contact portion side, and a second detecting portion disposed on the opposite side of the contact portion of the diaphragm as viewed from the horizontal line. Actuator. 6. The piezoelectric actuator according to claim 1, wherein the strain detecting section includes a detecting electrode, and a portion of the piezoelectric element on which the detecting electrode is arranged. Actuator. 7. The piezoelectric actuator according to claim 1, wherein the strain detecting section is a piezoelectric sensor arranged on a surface of the piezoelectric element. 8. A vibration plate having at least one piezoelectric element that generates a longitudinal vibration and a bending vibration that vibrates in a direction substantially orthogonal to the longitudinal vibration when a driving signal is supplied, and provided on the diaphragm. And a contact portion that is in contact with a driving target, and a distortion detection unit provided on the diaphragm and configured to detect distortion of the diaphragm when driving the driving target. A drive device for a piezoelectric actuator that drives the driven object by displacement of the contact portion due to vibration and bending vibration, and a drive signal generation unit that generates the drive signal whose frequency is corrected based on a control signal, A driving device for a piezoelectric actuator, comprising: a control signal generation unit that generates the control signal based on a signal detected from the distortion detection unit. 9. The driving device for a piezoelectric actuator according to claim 8, wherein the drive signal generation unit outputs a reference signal having a frequency corresponding to a voltage value of the control signal, and the reference signal. And a driver circuit for generating the drive signal based on the driving signal. 10. The driving device for a piezoelectric actuator according to claim 8, wherein the distortion detecting section is arranged to pass through a portion of the vibration plate, which is a node of the longitudinal vibration, in a direction orthogonal to the vibration direction of the longitudinal vibration. The control signal generation unit is disposed on the contact portion side when viewed from the extending horizontal line, and the control signal generation unit detects a maximum value of amplitude among the detected signals and outputs a peak signal; A delay circuit that outputs a delay signal delayed by a predetermined time; a comparison circuit that compares a voltage value of the peak signal with a voltage value of the delay signal to output a comparison result signal; A driving device for a piezoelectric actuator, comprising: a voltage adjusting circuit that adjusts a voltage value of a control signal in units of a predetermined voltage value. 11. The driving device for a piezoelectric actuator according to claim 8, wherein the strain detecting portion is arranged to pass through a portion of the diaphragm that becomes a node of the longitudinal vibration and to intersect at right angles with the vibration direction of the longitudinal vibration. The control signal generation unit is disposed on the contact portion side as viewed from the extending horizontal line, and the phase of the detected signal,
A phase difference-voltage conversion circuit that detects a phase difference from the phase of the drive signal and outputs a phase difference voltage signal having a voltage value corresponding to the phase difference; and a delay signal obtained by delaying the phase difference voltage signal by a predetermined time. A delay circuit that outputs a comparison result signal by comparing a voltage value of the phase difference voltage signal with a voltage value of the delay circuit, and receives a comparison result signal, and outputs a voltage of the control signal. A driving device for a piezoelectric actuator, comprising: a voltage adjusting circuit for adjusting a value in a predetermined voltage value unit. 12. The driving device for a piezoelectric actuator according to claim 8, wherein the distortion detecting section is arranged to pass through a portion of the vibration plate, which is a node of the longitudinal vibration, in a direction orthogonal to the vibration direction of the longitudinal vibration. The control signal generation unit is disposed on the contact portion side as viewed from the extending horizontal line, and the phase of the detected signal,
A phase difference-voltage conversion circuit that detects a phase difference from the phase of the drive signal and outputs a phase difference voltage signal having a voltage value corresponding to the phase difference; and a phase of the detection signal and a phase of the drive signal. A constant voltage circuit that outputs a reference phase difference signal having a voltage corresponding to the predetermined reference phase difference, a comparison circuit that compares the phase difference voltage signal with the reference phase difference signal and outputs a comparison result signal, A driving device for a piezoelectric actuator, comprising: a voltage adjusting circuit that receives a comparison result signal and adjusts a voltage value of the control signal in units of a predetermined voltage value. 13. The driving device for a piezoelectric actuator according to claim 8, wherein the strain detecting unit passes through a portion of the diaphragm that becomes a node of the longitudinal vibration, and is orthogonal to a vibration direction of the longitudinal vibration. A first detection portion disposed on the contact portion side as viewed from a horizontal line extending to the second portion, and a second detection portion disposed on the opposite side of the contact portion as viewed from the horizontal line in the diaphragm, The control signal generation unit includes a subtraction circuit that outputs a difference signal from a difference between signals detected from the first detection unit and the second detection unit, and a delay circuit that outputs a delay signal obtained by delaying the difference signal by a predetermined time. A comparison circuit that compares the voltage value of the difference signal with the voltage value of the delay circuit and outputs a comparison result signal; and receiving the comparison result signal, and sets the voltage value of the control signal in units of a predetermined voltage value. And a voltage adjusting circuit for adjusting. Drive apparatus for a piezoelectric actuator according to claim. 14. A vibration plate having at least one piezoelectric element that generates a longitudinal vibration and a bending vibration that vibrates in a direction substantially orthogonal to the longitudinal vibration when a drive signal is supplied thereto, and provided on the diaphragm. And a contact portion that is in contact with the driving target, and a distortion detection unit provided on the diaphragm and configured to detect a distortion of the diaphragm when driving the driving target. A method for driving a piezoelectric actuator that drives the driven object by displacement of the contact portion caused by vibration and bending vibration, wherein a driving signal generating step of generating the driving signal with frequency correction based on a control signal; A control signal generating step of generating the control signal based on a signal detected by the distortion detecting unit. 15. The method of driving a piezoelectric actuator according to claim 14, wherein the distortion detecting section passes through a portion of the diaphragm that becomes a node of the longitudinal vibration and extends in a direction perpendicular to the vibration direction of the longitudinal vibration. The control signal generating step calculates the maximum value of the amplitude of the detected signal, and generates the control signal based on the maximum value. Driving method of the piezoelectric actuator. 16. The driving method of a piezoelectric actuator according to claim 15, wherein the distortion detecting section passes through a portion of the diaphragm that becomes a node of the longitudinal vibration and extends in a direction orthogonal to the vibration direction of the longitudinal vibration. The control signal generation step calculates a phase difference between the phase of the detected signal and the phase of the drive signal, and generates the control signal from the phase difference. A method for driving a piezoelectric actuator. 17. The driving method of a piezoelectric actuator according to claim 15, wherein the strain detecting section extends in a direction orthogonal to the vibration direction of the longitudinal vibration through a portion of the diaphragm that becomes a node of the longitudinal vibration. A first detection unit disposed on the contact portion side as viewed from a horizontal line, and a second detection unit disposed on the opposite side of the vibration plate from the contact portion as viewed from the horizontal line; The driving method of the piezoelectric actuator, wherein the signal generation step calculates a difference between signals respectively detected from the first detection unit and the second detection unit, and generates the control signal from the difference. 18. A vibration plate having at least one piezoelectric element that generates a longitudinal vibration and a bending vibration that vibrates in a direction substantially orthogonal to the longitudinal vibration when a driving signal is supplied, and provided on the diaphragm. And a contact portion that is in contact with the driving target, and a distortion detection unit provided on the diaphragm and configured to detect a distortion of the diaphragm when driving the driving target. A piezoelectric actuator that drives the driven object by a displacement of the abutting portion caused by vibration and bending vibration; a driving signal generating unit that generates the driving signal whose frequency is corrected based on a control signal; and the distortion detecting unit. A driving device having a control signal generation unit that generates the control signal based on the detected signal; a calendar display wheel driven by the piezoelectric actuator; and an electric power supplied to the driving device. Timepiece characterized by comprising a power supply for feeding and. 19. A vibration plate having at least one piezoelectric element that generates a longitudinal vibration and a bending vibration that vibrates in a direction substantially orthogonal to the longitudinal vibration when a driving signal is supplied thereto, and is provided on the diaphragm. And a contact portion that is in contact with the driving target, and a distortion detection unit provided on the diaphragm and configured to detect a distortion of the diaphragm when driving the driving target. A piezoelectric actuator that drives the driven object by the displacement of the abutting portion due to vibration and bending vibration; a driving signal generating unit that generates the driving signal whose frequency is corrected based on a control signal; and the distortion detecting unit. A portable device comprising: a driving device having a control signal generation unit that generates the control signal based on a detected signal; and a battery that supplies power to the driving device.