JP2002223577A - Piezoelectric actuator, clock, mobile apparatus, and designing and manufacturing methods of the piezoelectric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve stable drive of a piezoelectric actuator, while using a drive circuit of a simple configuration. SOLUTION: Electrodes 33a, 33c are formed at two corners on a piezoelectric element 30 of a diaphragm 10, and an electrode 33b is formed on the entire surface other than the corners. A drive circuit 500 is connected in parallel with the electrodes 33a, 33c and the electrode 33b, and a capacitor 505 for adjusting a frequency is connected between the electrodes 33a, 33c and the drive circuit 500. A drive voltage, that is supplied from an oscillating circuit 504, is supplied at a frequency, as it is, to the electrode 33b, while the drive voltage of a frequency adjusted by the capacitor 505 is supplied to the electrodes 33a, 33c. Here, as the capacitor 505, a capacitor is used of such a capacity that adjusts the frequency, in such a way that the vertical oscillations of the diaphragm 10 including the capacitor 505 as seen from the drive circuit 500 almost matches with to the resonance frequency of the curvature oscillations.

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 watch provided with the same, a portable device, and a method of designing and manufacturing a piezoelectric actuator.

[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 a piezoelectric element is very small, depending on the applied voltage, and is usually on the order of submicron.
2. Description of the Related Art Displacement is amplified by some kind of amplifying mechanism and transmitted to a rotor. However, when using an amplification mechanism, energy is consumed to move itself,
In addition to the problem that the efficiency is reduced, there is also a problem that the size of the device is increased. Also,
Through the amplifying mechanism, it may be difficult to stably transmit the driving force to the rotor.

[0004] In addition, small portable devices such as wristwatches are driven by batteries, so that it is necessary to reduce power consumption and driving voltage. Therefore, when a piezoelectric actuator is incorporated in such a portable device, it is particularly required that the energy efficiency is high and the driving voltage is low.

[0005] In a timepiece or the like, a calendar display mechanism for displaying the day and day of the week intermittently transmits the rotational driving force of an electromagnetic step motor to a date wheel and the like via a wheel train for hand movement. It is common to feed and drive a date wheel. On the other hand, since a wristwatch is carried around a wrist with a belt, there has been a long-standing demand for a thin wristwatch for convenient carrying. To pursue a reduction in thickness, it is necessary to reduce the thickness of the calendar display mechanism. However, since a step motor is configured by incorporating components such as a coil and a rotor in an out-of-plane direction, there is a limit in reducing its thickness. For this reason, the conventional calender mechanism using the step motor has a problem that it is not suitable for thinning the structure.

In particular, a clock having a calendar display mechanism,
In order to share the mechanical system of hand movement (so-called movement) with a watch without such a mechanism, it is necessary to configure a calendar display mechanism on the dial side. It is difficult to make it thin enough to be configured. Therefore, in the conventional timepiece, it is necessary to separately design and manufacture the mechanical system of the hand movement depending on the presence or absence of the display mechanism, which has been a problem in improving the productivity.

[0007]

As described above, a piezoelectric actuator which is highly efficient and can be mounted on a small device is driven by a thin diaphragm composed of a piezoelectric element having a longitudinal direction or the like. By applying a voltage, a method of exciting both longitudinal vibration that expands and contracts in the longitudinal direction and bending vibration that swings in the width direction orthogonal to the longitudinal direction can be considered. By exciting the longitudinal vibration and the bending vibration in this manner, a large vibration is generated by the diaphragm, so that the driving efficiency can be improved and the thickness can be reduced.

However, when considering the impedance characteristics of a thin diaphragm having a longitudinal direction (for example, a rectangular diaphragm), the resonance frequency of the longitudinal vibration of the diaphragm,
Since the resonance frequency of the bending vibration is different, stable driving may not be performed when a drive circuit is configured based on one of the resonance frequencies. Therefore,
In order to stably drive an actuator that excites both longitudinal vibration and bending vibration to the diaphragm, it is necessary to configure a drive circuit that takes into account two resonance frequencies such as longitudinal vibration and bending vibration. A complicated drive circuit such as providing a drive circuit and a drive circuit for bending vibration excitation had to be used.

The present invention has been made in view of the above circumstances, and a piezoelectric actuator that realizes more stable driving while using a driving circuit having a simple configuration, a timepiece, a portable device, and a timepiece having the same. An object of the present invention is to provide a method for designing and manufacturing a piezoelectric actuator.

[0010]

In order to solve the above-mentioned problems, a piezoelectric actuator according to the present invention comprises a support and a plate-shaped piezoelectric element having a longitudinal direction, and is supported so as to be capable of vibrating with respect to the support. And a contact portion provided on one end side in the longitudinal direction of the diaphragm and brought into contact with an object to be driven, and a plurality of divided electrode portions provided on the piezoelectric element, A driving circuit for supplying a driving voltage of a single frequency to each electrode unit, and supplying the driving voltage to the piezoelectric element via each of the electrode units, thereby causing the piezoelectric element to vibrate so that the vibration plate A piezoelectric actuator that causes the longitudinal vibration and bending vibration that swings in a width direction orthogonal to the longitudinal direction, and drives the driven object by displacement of the contact portion caused by the vibration, wherein the driving circuit and the driving circuit , The drive Of the respective electrode portions connected in parallel to a circuit, the electrode portion is provided between the electrode portion provided for electrically exciting the bending vibration or any of the other electrode portions, and supplied from the drive circuit. Frequency adjusting means for adjusting the frequency of the driving voltage to be applied, the frequency adjusting means depending on a difference between a resonance frequency of a predetermined order of longitudinal vibration of the diaphragm and a resonance frequency of a predetermined order of the bending vibration. The resonance frequency of the longitudinal vibration of the predetermined order and the resonance frequency of the bending vibration of the predetermined order are substantially matched by performing the frequency adjustment.

According to this structure, the frequency adjusting means sends the driving signal from the driving circuit such that the resonance frequency of the predetermined order longitudinal vibration and the predetermined order bending vibration of the diaphragm including the frequency adjusting means substantially coincide with each other. Since the frequency is adjusted and supplied to either the electrode part for exciting the bending vibration or the other electrode part, the drive circuit must have the characteristic that the resonance frequencies of the longitudinal vibration and the bending vibration are almost the same. A circuit configuration for driving the board is sufficient. That is,
In a piezoelectric actuator that drives a driven object by applying a driving voltage to a piezoelectric element to generate a longitudinal vibration and a bending vibration on a diaphragm, two types of vibrations, such as longitudinal vibration and bending vibration,
The stable driving of the piezoelectric actuator can be performed without using a complicated configuration in which two driving circuits are configured in consideration of different resonance frequencies of two vibrations.

In the above structure, the electrode section to which the driving voltage adjusted by the frequency adjusting means is supplied is provided near a position where the amplitude of the bending vibration generated on the diaphragm becomes a maximum value. Is also good. Further, in the above configuration, the frequency adjusting means may include a capacitor or a coil. Further, in the above configuration, the drive circuit may include a self-excited oscillation circuit using the diaphragm as a vibrator, and may supply a drive voltage having a frequency oscillated from the self-excited oscillation circuit. . Also,
In the above configuration, the vibration plate may have a structure in which the piezoelectric element and a reinforcing plate are stacked.

Further, a timepiece according to the present invention includes the piezoelectric actuator having the above-described configuration, and a ring-shaped calendar display wheel driven by the piezoelectric actuator.

Further, a portable device according to the present invention includes the piezoelectric actuator configured as described above, and a battery for supplying power to the piezoelectric actuator.

Further, a method of designing a piezoelectric actuator according to the present invention includes a vibrating plate having a support and a plate-like piezoelectric element having a longitudinal direction, the vibrating plate being supported on the support so as to vibrate. A contact portion provided on one end side in the longitudinal direction of the diaphragm and brought into contact with a driving target; a plurality of divided electrode portions provided on the piezoelectric element; A drive circuit that supplies a drive voltage of one frequency, the drive circuit, and the electrode unit or the electrode unit that is provided to electrically excite the bending vibration among the electrode units that are connected in parallel to the drive circuit. Frequency adjusting means for adjusting the frequency of a drive voltage supplied from the drive circuit, provided between any of the other electrode portions, and the piezoelectric element To supply Vibrating the piezoelectric element to cause the vibrating plate to generate the longitudinal vibration and the bending vibration swinging in a width direction orthogonal to the longitudinal direction, and the displacement of the abutting portion accompanying the vibration causes the driven object to move. A method of designing a piezoelectric actuator to be driven, wherein the step of measuring impedance characteristics of the diaphragm, and based on the impedance characteristics, a resonance frequency of a predetermined order of the longitudinal vibration of the diaphragm, Obtaining a resonance frequency of a predetermined order; and, based on the resonance frequency of the longitudinal vibration and the resonance frequency of the bending vibration obtained from the impedance characteristics, the vertical order of the predetermined order of the diaphragm including the frequency adjusting means. The resonance frequency of the predetermined order of the longitudinal vibration of the diaphragm and the bending frequency of the vibration plate are set so that the resonance frequency of the vibration and the resonance frequency of the bending vibration of the predetermined order substantially match. It is characterized by comprising a step of determining said frequency adjusting means for performing a difference frequency adjustment according to the predetermined order of the resonance frequency of the dynamic.

In the above-mentioned design method, when the frequency adjusting means is a capacitor or a coil, the step of determining the frequency adjusting means may determine the capacitance of the capacitor or the coil.

Further, a method of manufacturing a piezoelectric actuator according to the present invention comprises a support and a plate-like piezoelectric element having a longitudinal direction, wherein the vibration plate is supported so as to be capable of vibrating with respect to the support. A contact portion provided on one end side in the longitudinal direction of the diaphragm and brought into contact with a driving target; a plurality of divided electrode portions provided on the piezoelectric element; A drive circuit that supplies a drive voltage of one frequency, the drive circuit, and the electrode unit or the electrode unit that is provided to electrically excite the bending vibration among the electrode units that are connected in parallel to the drive circuit. Frequency adjusting means for adjusting the frequency of a drive voltage supplied from the drive circuit, provided between any of the other electrode portions, and the piezoelectric element To supply Vibrating the piezoelectric element to cause the vibrating plate to generate the longitudinal vibration and the bending vibration swinging in a width direction orthogonal to the longitudinal direction, and the displacement of the abutting portion accompanying the vibration causes the driven object to move. A method of manufacturing a piezoelectric actuator to be driven, wherein impedance characteristics of the diaphragm are determined, a resonance frequency of a predetermined order of the longitudinal vibration of the diaphragm determined from the impedance characteristics, and a resonance of a predetermined order of the bending vibration. The longitudinal vibration of the diaphragm based on the frequency, such that the resonance frequency of the longitudinal vibration of the predetermined order and the resonance frequency of the bending vibration of the predetermined order shown in the impedance characteristic of the diaphragm including the frequency adjusting unit substantially match. Determine the frequency adjusting means for performing frequency adjustment according to the difference between the resonance frequency of the predetermined order of the predetermined order and the resonance frequency of the predetermined order of the bending vibration, and determine A step of connecting the frequency adjusting means between the drive circuit and the electrode section provided for electrically exciting the bending vibration among the electrode sections connected in parallel to the drive circuit; It is characterized by having.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 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 A1 includes a diaphragm 10 and a rotor 10 that expand and contract in an in-plane direction (a direction parallel to the plane of the drawing).
0. The rotor 100 is a base plate (support) 1
03 is rotatably supported and arranged at a position where it comes into contact with the diaphragm 10, and when the outer peripheral surface thereof is hit by the vibration generated in the diaphragm 10, the diaphragm 10 is driven to rotate in the direction shown by the arrow in the figure. It has become.

Next, the calendar display mechanism is connected to the piezoelectric actuator A1, and is driven by its driving force. The main part of the calendar display mechanism is the rotor 10
It is roughly composed of a reduction wheel train for reducing the rotation of 0 and a ring date dial 50. In addition, the reduction wheel train is a daily intermediate wheel 4
0 and a date wheel 60 are provided.

When the diaphragm 10 vibrates in the in-plane direction as described above, the rotor 100 in contact with the diaphragm 10 is rotated clockwise. Rotor 10
The rotation of 0 is transmitted to the date wheel 60 via the date intermediate wheel 40, and the date wheel 60 rotates the date wheel 50 clockwise. Thus, the rotor 1
The transmission of the force from the rotor 100 to the reduction gear train and 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 one embodiment of the present invention. In the figure, a calendar mechanism provided with the above-described piezoelectric actuator A1 is incorporated in a mesh portion. However, in order to make the entire timepiece thin, the thickness D in which the calendar mechanism can be incorporated is extremely small. 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 7 for driving the hands 72 is provided below the dial 70.
3, and a drive circuit (not shown) described later.

In the above configuration, the piezoelectric actuator A1 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 as in a conventional step motor. I have. Therefore, it is structurally suitable for thinning. Therefore, the thickness of the calendar display mechanism can be reduced, and the thickness of the entire timepiece can be reduced. For example,
Various wristwatches having a power generation function have been proposed. 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, and as described above, the calendar It can be said that the merit of reducing the thickness of the display mechanism is great. Further, the movement 73 can be shared between a timepiece having a calendar display mechanism and a timepiece having no such display mechanism, and productivity can be improved.

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, and a base plate 103 'is a second bottom plate having a step partially with respect to the base plate 103.

Above the rotor 100 driven to rotate by the piezoelectric actuator A1, a gear 10 coaxial with the rotor 100 and rotated with the rotor 100 is provided.
0c is provided. The date turning intermediate wheel 40 has a large diameter portion 4
b 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. The rotation of the gear 100c associated with the rotor 100 causes the gear 100c to mesh with the gear 100c. The large-diameter portion 4b is rotated to rotate the intermediate wheel 40. 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 plate intermediate wheel 40 is provided on the main plate 103 '.
And a bearing (not shown) connected to the shaft 41 is formed inside the date intermediate wheel 40. Accordingly, the date intermediate wheel 40 is provided rotatably with respect to the main plate 103 '. In addition,
The rotor 100 also has a bearing (not shown) inside and is rotatably supported on the main plate 103.

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 main 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
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 ground 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. In addition, when a manually driven wheel meshing with the internal gear 5a is provided and the user performs a predetermined operation on the crown (not shown),
The date indicator 50 may be driven.

C. Next, the piezoelectric actuator A1 according to the present embodiment will be described. As shown in FIG.
Reference numeral 1 denotes a long plate-shaped diaphragm 1 which is formed long in the left-right direction in the figure.
0 and a support member 11 for supporting the diaphragm 10 on the main plate 103 (see FIGS. 1 and 3).

A protruding portion 36 is provided at the longitudinal end 35 of the diaphragm 10 so as to project toward the rotor 100.
The projection 36 is brought into contact with the outer peripheral surface of the rotor 100 in a state of being pressed by a spring member 300 or the like described later. By providing such protrusions 36, it is only necessary to perform work such as polishing only on the protrusions 36 in order to maintain the state of the contact surface with the rotor 100 and the like. Becomes easier. The protrusion 36 may be made of a conductor or a non-conductor. However, if the protrusion 36 is made of a non-conductor, the piezoelectric element 30, 31 can be prevented from being short-circuited.

Further, as shown in the figure, in the present embodiment, the projection 36 has a curved shape protruding toward the rotor 100 in plan view. By forming the protrusion 36 in contact with the rotor 100 into a curved shape in this manner, even when the positional relationship between the rotor 100 and the diaphragm 10 varies (due to dimensional variations, etc.), the rotor 10 having a curved surface may be used.
The state of contact between the outer peripheral surface of No. 0 and the curved projection 36 does not change much. Therefore, a stable contact state between the rotor 100 and the protrusion 36 can be maintained.

One end 37 of a substantially L-shaped support member 11 is attached to the rotor 100 at a position slightly closer to the rotor 100 than the center in the longitudinal direction. The support member 11 has one end 37
From the direction substantially perpendicular to the longitudinal direction of the diaphragm 10 to the rotor 100 side, and the other end portion 38 of the bent support member 11 is rotatable to the ground plate 103 (see FIG. 1) by screws 39. It is supported by. That is, the support member 11 is rotatable about the screw 39, and the position of the diaphragm 10 with respect to the rotor 100 can be adjusted by rotating the support member 11.

A portion 11a of the support member 11 extending substantially parallel to the longitudinal direction of the diaphragm 10 is provided with a spring member 300.
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, when the force pressing the support member 11 upward increases, the support member 11 rotates counterclockwise in the figure around the screw 39, so that the force of the protrusion 36 pressing the rotor 100 increases. . On the other hand, when the force pressing the support member 11 upward decreases, the support member 11 rotates clockwise, so that the force of the protrusion 36 pressing the rotor 100 decreases. That is, by adjusting the position of the other end 300c, the pressing force applied to the rotor 100 by the protrusion 36 can be adjusted, and thereby the drive characteristics of the piezoelectric actuator A1 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.
Reinforcing plate 32 of stainless steel or the like having a smaller thickness than 31
Are arranged in a laminated structure. By arranging the reinforcing plate 32 between the piezoelectric elements 30 and 31 in this manner, damage to the diaphragm 10 due to an external impact force such as excessive amplitude or drop of the diaphragm 10 is reduced, and durability is reduced. Can be improved. Further, as the reinforcing plate 32, the piezoelectric element 3
By using a material whose wall thickness is smaller than 0,31,
Vibration of the piezoelectric elements 30 and 31 is prevented as much as possible. If the support member 11 described above is formed integrally with the reinforcing plate 32, the manufacturing process can be simplified.

Electrodes 33 are arranged on the surfaces of the vertically arranged piezoelectric elements 30 and 31, respectively. An AC drive voltage is supplied to the piezoelectric elements 30 and 31 via the electrodes 33 from a drive circuit described later. Here, as the piezoelectric elements 30, 31, lead zirconate titanate (PZT (trademark)), quartz, lithium niobate,
Barium titanate, lead titanate, lead metaniobate, polyvinylidene fluoride, lead zinc niobate ((Pb (Zn1 / 3-Nb2 /
3) 03 1-x-Pb Ti 03 x) x varies depending on the composition. x = 0.09), lead scandium niobate ((Pb ((Sc1 / 2Nb1 / 2) 1-x
Tix)) 03) x varies depending on the composition. x = 0.09) or the like.

When the polarization directions of the piezoelectric elements 30 and 31 are reversed, for example, as shown in FIG. 6, the potentials on the upper surface, the center and the lower surface are + V, 0 and + V (or -V, 0 and -V), respectively. When a driving voltage is applied from the driving circuit 500 (to be described in detail later), the plate-shaped piezoelectric element is displaced so as to expand and contract. In this embodiment, the displacement due to such expansion and contraction is used. are doing. The piezoelectric elements 30 and 31
If the polarization directions of the top and bottom are the same,
The potential on the lower surface is + V, 0, -V (or -V, 0,
+ V).

As shown in FIG. 7, the piezoelectric actuator A
In FIG. 1, three electrodes 33a, 33b, and 33c are formed on the surfaces of rectangular piezoelectric elements 30, 31 (only the surface on the side of the piezoelectric element 30 is shown, but the piezoelectric element 31 is also the same). . The electrode 33a is a substantially rectangular piezoelectric element 30.
Of the four corners, the electrode having a small area formed at the corner where the protrusion 36 is formed, and the electrode 33c is the electrode 3c.
This is an electrode having a small area formed at a corner portion facing 3a. The electrode 33b is an electrode formed so as to cover almost the entire area of the piezoelectric element 30 except for the electrodes 33a and 33c. The electrodes 33a, 33b, and 33c are also formed on the surface on the side of the piezoelectric element 31 at the same positions as the electrodes shown in FIG. 7, and the electrodes 33a formed on the piezoelectric element 30 and the electrodes 33a formed on the piezoelectric element 31 are connected to each other. , Electrodes 33b and electrode 3
3c are connected to each other. Therefore, the drive circuit is provided with the electrodes 33a, 33 formed on one of the piezoelectric elements.
b, 33c, a drive voltage can be supplied to the electrodes formed on both surfaces. In addition to the connection between the electrodes on both surfaces as described above, the drive circuit and the electrodes on each surface may be individually connected. Such electrodes 33a, 33b, and 33c may be formed individually by vapor deposition or the like, or may be formed by etching once after forming electrodes in the entire area.
The electrode 33a is formed by a method such as a dicing saw or laser processing.
It may be formed by removing a portion between the electrode 33b and the electrode 33b or a portion between the electrode 33b and the electrode 33c.

When an alternating voltage is applied to the piezoelectric elements 30 and 31 from the drive circuit 500 via the electrodes 33a, 33b and 33c, the vibration plate 10 having the above-described configuration is used.
Vibration is caused by the expansion and contraction of 0 and 31. At this time, as shown in FIG. 8, the diaphragm 10 vibrates by longitudinal vibration that expands and contracts in the longitudinal direction, whereby the diaphragm 10 vibrates in the direction indicated by the arrow in FIG. When the longitudinal vibration is excited in the diaphragm 10 in this manner, as shown in FIG. 9, a rotational moment about the center of gravity of the diaphragm 10 is generated due to the imbalance of the weight balance of the diaphragm 10. The bending moment induces bending vibration in which the diaphragm 10 swings in the width direction (the vertical direction in FIG. 4). In this embodiment,
In order to induce a larger bending vibration, a larger rotational moment is generated by providing a balance portion 18 on the end 16 of the diaphragm 10 opposite to the side on which the protrusion 36 is provided. Here, both ends in the longitudinal direction of the diaphragm 10 are portions where the amplitude of the bending vibration has a maximum value (antinode of the bending vibration).
33c is provided. That is, the electrode 33b excites the vibration plate 10 as a whole in the longitudinal direction, and generates bending vibration mechanically induced by weight balance or the like. The electrodes 33a and 33c are used to partially expand and contract the piezoelectric element in order to further increase the amplitude of the bending vibration thus generated, and to electrically excite the bending vibration. By providing the electrodes 33a and 33c at the portions where the amplitude of the bending vibration of the diaphragm 10 is maximized, the piezoelectric elements 30 and 31 in these portions can be expanded and contracted to further increase the amplitude of the bending vibration. It is. That is, the electrode 33
By applying a voltage to b, the entire longitudinal vibration of the diaphragm 10 is excited to generate bending vibration mechanically induced by weight balance or the like, while the electrodes 33a, 3
By applying a voltage to 3c to partially expand and contract the piezoelectric element, the bending vibration is electrically excited, and the amplitude of the mechanically induced bending vibration can be further increased.

When such longitudinal vibration and bending vibration are generated and the two are coupled, the contact portion of the projection 36 of the diaphragm 10 with the rotor 100 is formed along the elliptical orbit as shown in FIG. Will move. As described above, the protrusion 36 draws an elliptical orbit, so that when the protrusion 36 is in a position swelling toward the rotor 100, the rotor 10
0 and the protruding portion 36 are in pressure contact with each other, and when the protruding portion 36 is in a swelling position at a position retracted from the rotor 100 side, the rotor 100 and the protruding portion 36 are separated from each other (or even if the protruding portion 36 contacts, Smaller). Therefore, the rotor 100 can be driven in the direction in which the protrusion 36 is displaced while the pressing forces of both are large, that is, when the protrusions 36 are in the swelled position on the rotor 100 side.

D. Driving Configuration of Piezoelectric Actuator Next, a configuration in which a driving voltage is applied to the piezoelectric elements 30 and 31 of the piezoelectric actuator A1 incorporated in the calendar display mechanism to drive the piezoelectric actuator A1 will be described. For clarity, the impedance characteristics of a mechanical structure such as the diaphragm 10 will be described first.

By keeping the force constant against a mechanical structure such as the diaphragm 10 and gradually increasing the excitation frequency,
At a specific frequency, the response of the amplitude of the structure becomes a maximum value (that is, the impedance becomes a local minimum value), and then becomes a local minimum value (a local maximum value of the impedance). 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 a rectangular structure such as the diaphragm 10 generally has a relationship between impedance and frequency as illustrated in FIG. In the illustrated example, the minimum value of the impedance of a certain order (for example, primary) of longitudinal vibration is fkHz, the minimum value of the impedance of bending vibration of a certain order (for example, second order) is FkHz, and the impedance of both vibrations is The local minima are different (where Δf = F−f is F *
It is desirable to be in the range of about 0.01, for example, F = 200H
In the case of z, f = within the range of 198 Hz to 202 Hz).

The resonance frequency of each vibration is the frequency at which each vibration oscillates most, and a driving voltage of any frequency is applied to the piezoelectric element 3 in order to excite each vibration and to what extent.
This is an important value in the design items that determine whether to apply 0 or 31. In order to stably perform the drive control of supplying the drive voltage of the designed frequency to the piezoelectric elements 30 and 31, it is necessary to perform the control based on the value of the resonance frequency of each vibration. Conventionally, as a driving method of a piezoelectric actuator using a rectangular vibration plate, there are two driving methods, a driving circuit in which the resonance frequency of different longitudinal vibration is considered as described above and a driving circuit in which the resonance frequency of bending vibration is considered. There is a so-called two-phase drive in which a circuit is provided, but in this case, the drive circuit naturally becomes complicated. The drive configuration of the piezoelectric actuator A1 according to the present embodiment does not use the two-phase drive that makes the circuit configuration complicated as described above.
A drive configuration capable of performing stable drive control is adopted. Hereinafter, a drive configuration of the piezoelectric actuator A1 will be described with reference to FIG.

As shown in the figure, the drive circuit 500 includes a midnight detecting means 501, a control circuit 503, a date sending detecting means 502, and an oscillation circuit 504. 0 am
The hour detecting means 501 is a mechanical switch incorporated in the movement 73 (see FIG. 2), and outputs a control signal to the control circuit 503 at midnight. Further, the date feed detecting means 502 includes the above-described leaf spring 64 and the contact 65.
(See FIG. 1), and outputs a control signal to the control circuit 503 when the leaf spring 64 and the contact 65 come into contact, that is, when the end of date feeding is detected.

The control circuit 503 includes the midnight detecting means 50.
An oscillation control signal is output to the oscillation circuit 504 on the basis of the control signal supplied from the control signal 1 and the control signal supplied from the date sending detection unit 502. Here, the oscillation control signal is 0 am
When the midnight is detected by the hour detecting means 501, the signal rises from a low level to a high level, and when the date sending detecting means 502 detects the end of the date feeding, the signal falls from the high level to a low level.

The oscillation circuit 504 is configured such that, when driving the diaphragm 10 illustrated in FIG. 10, the oscillation frequency substantially matches the resonance frequency of the primary longitudinal vibration. Note that the oscillation circuit 504 may be configured in a Colpitts type, for example. The power supply to the oscillation circuit 504 is controlled by an oscillation control signal. The power is supplied when the oscillation control signal is at a high level, and the power supply is stopped when the oscillation control signal is at a low level.

As described above, the date turning intermediate wheel 40 rotates once a day, but the period is a limited time starting from midnight. Therefore, it is sufficient that the oscillation circuit 504 oscillates only during the period. In the drive circuit 500 of this example, the power supply to the oscillation circuit 504 is controlled by the oscillation control signal, so that the operation of the oscillation circuit 504 is completely completed during the period when the date intermediate wheel 40 does not need to be rotated. Has been stopped. Therefore, power consumption of the oscillation circuit 504 can be reduced.

As described above, the driving voltage of the frequency (frequency between the resonance frequency of the longitudinal vibration and the frequency of the bending vibration) oscillated by the oscillation circuit 504 is applied to the electrodes 33a, 33b, 3
The power is supplied to the piezoelectric elements 30 and 31 via 3c. Here, the electrodes 33a and 33c and the electrode 33b
Are connected in parallel to the drive circuit 500, and the electrodes 33
A capacitor (frequency adjusting means) 505 is connected between the driving circuits 500 and a and 33c. As a result, the electrode 33b is supplied with the drive voltage having the frequency oscillated from the drive circuit 500, while the electrodes 33a and 33c are supplied with the frequency supplied from the drive circuit 500 using the capacitor 505.
And a drive voltage having the adjusted frequency is supplied.

Here, when the impedance characteristic (see FIG. 10) of the diaphragm 10 in which the resonance frequencies of the longitudinal vibration and the bending vibration are different from each other is viewed from the drive circuit 500 as described above, the capacitor 505 is as shown in FIG. The frequency is adjusted so that the resonance characteristics of the longitudinal vibration and the bending vibration have impedance characteristics substantially coincident with each other. That is, the capacitor 505 is a capacitor having a capacity that adjusts the frequency so that the resonance frequency of the longitudinal vibration and the resonance frequency of the bending vibration indicated by the impedance characteristics of the diaphragm 10 including the capacitor 505 as a constituent element substantially match.

Next, a method for determining the capacity of the capacitor 505 for performing the above-described frequency adjustment will be described.
First, the resonance frequencies of the longitudinal vibration and the bending vibration are determined in consideration of the performance required for the piezoelectric actuator, and the dimensions of the diaphragm 10 are calculated based on the determined resonance frequencies. Here, as a method of calculating the dimensions of the diaphragm 10, various known methods can be used which are calculated from a finite element method, an approximate expression based on an empirical rule, or the like. Next, the impedance characteristics of the diaphragm 10 having the dimensions determined in this manner (FIG. 1)
1), an equivalent circuit of longitudinal vibration and bending vibration of the diaphragm 10 as shown in FIG. 14A is calculated by a known calculation method such as least square fitting using a known measuring device such as an impedance analyzer. Here, the calculated equivalent circuit TA of the longitudinal vibration is represented by the capacitor C1, the coil L1, and the resistor R1, and the equivalent circuit KA of the bending vibration.
Is represented by a capacitor C2, a coil L2 and a resistor R2. Note that the capacitor C is a capacitor component of the piezoelectric elements 30 and 31. In the above equivalent circuit,
The resistances R1 and R2 represent various losses such as mechanical loss, dielectric loss, and loss due to displacement of crystal grain boundaries in the bonded portion and the support portion of the diaphragm 10, and actually change to heat and the like. Component.

Next, as described above, the capacitor 505 is connected between the driving circuit 500 and the electrodes 33a and 33c for electrically exciting the bending vibration.
The equivalent circuit KA ′ of the bending vibration of the diaphragm 10 including
4 (b). That is, the capacitor C3 (= capacitor 505) is connected in series to the bending vibration equivalent circuit KA shown in FIG.

Therefore, in the equivalent circuit shown in FIG. 14B, in order to match the frequencies of the bending vibration and the longitudinal vibration, C3 (capacitor capacitance) satisfying the following equation is obtained, and the obtained capacitor C3 is replaced by a capacitor. 505 may be connected between the drive circuit 500 and the electrodes 33a and 33c.

(Equation 1) Here, C1, C2, L1, and L2 are known from the impedance characteristic of the diaphragm 10, and the capacitance of the capacitor C3 can be obtained by solving the above equation for C3.
Therefore, when manufacturing the piezoelectric actuator A1, the capacitor 505 having the capacity determined by the above-described method is used.
May be connected between the drive circuit 500 and the electrodes 33a and 33c.

E. Operation of Calendar Display Mechanism Next, an automatic updating operation of the calendar display mechanism including the piezoelectric actuator A1 having the above-described configuration will be described with reference to FIGS. 1, 3, 4, and 12. At midnight on each day, the midnight detection means 501 detects that it is midnight, and the control circuit 503 outputs an oscillation control signal to the oscillation circuit 504. As a result, the driving voltage having a frequency substantially equal to the resonance frequency of the longitudinal vibration of the diaphragm 10 is applied from the oscillation circuit 504 to the electrodes 33a, 33b, 3
It is supplied to the piezoelectric elements 30 and 31 via 3c. Here, a drive voltage whose frequency has been adjusted by the capacitor 505 is supplied to the electrodes 33a and 33c.

The driving voltage from the driving circuit 500 is applied to the electrode 33.
a, 33b, 33c, the piezoelectric elements 30, 3
The portion of the electrode 1 where the electrode 33b is formed flexes and vibrates due to expansion and contraction, and the diaphragm 10 vibrates longitudinally. As described above, when the polarization directions (indicated by arrows in the drawing) of the piezoelectric elements 30 and 31 are the same, the potentials of the upper surface, the center, and the lower surface are + V, 0, −V (or −V, −V, respectively). 0, + V). 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. 6). Here, the electrode 33b
Is closer to the resonance frequency of the longitudinal vibration, so that a larger longitudinal vibration can be excited. When the longitudinal vibration is electrically excited in this way,
Flexural vibration is mechanically induced by the imbalance of the weight balance of the diaphragm 10. Also, the piezoelectric elements 30, 3
The flexural vibration is electrically excited by the expansion and contraction of the portion where the electrodes 33a and 33c are formed in 1, whereby the amplitude of the mechanically induced flexural vibration becomes larger. The electrical excitation of this bending vibration is also performed by the capacitor 505 with a drive voltage having a frequency close to the resonance frequency of the bending vibration, so that the amplitude of the electrically excited bending vibration becomes large. By causing the vibration plate 10 to generate longitudinal vibration and bending vibration having a large amplitude, the protrusions 36 are displaced along a larger elliptical orbit, and as a result, the rotor 100 can be driven with high efficiency.

When the piezoelectric actuator A1 is driven by the drive circuit 500 in this manner, the rotor 100 rotates clockwise in FIG. 4, and accordingly, the date intermediate wheel 40 starts rotating counterclockwise. I do.

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. Therefore, 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 indicator 50
Is rotated clockwise by one tooth (corresponding to a date range of 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 driving voltage ends, and the rotation of the date intermediate wheel 40 stops. Therefore, the date turning intermediate wheel 40 rotates once a day.

As described above, in this embodiment, the calendar display mechanism can be driven with high efficiency using the thin piezoelectric actuator A1 that can be installed in a limited space such as a wristwatch. In the piezoelectric actuator A1, the rotor 10 can be driven with high efficiency by electrically exciting the vibration plate 10 with two vibrations, that is, a vertical vibration and a bending vibration. In the case where two vibrations are excited as described above, when two vibrations are generated stably as designed, the drive circuit considers each of two resonance frequencies such as longitudinal vibration and bending vibration of the diaphragm 10. In this embodiment, the capacitor 505 having the capacitance determined as described above is connected between the drive circuit 500 and the electrodes 33a and 33c, thereby simplifying the drive circuit. It is possible. That is, by connecting the capacitor 505, the resonance frequencies of the longitudinal vibration and the bending vibration of the diaphragm 10 including the capacitor 505 viewed from the drive circuit 500 are matched, whereby the drive circuit can be simplified. 50
Stable driving can be realized even when a simple type such as Colpitts type 4 is used. In the present embodiment, the resonance frequencies of the longitudinal vibration and the bending vibration of the diaphragm 10 including the capacitor 505 viewed from the drive circuit 500 are completely matched from the viewpoint of obtaining the effect of simplifying the drive circuit as described above. It is not necessary to perform the control, and if the two frequencies are almost the same, control can be performed assuming that the two frequencies are the same when viewed from the drive circuit side. For example, in the case of impedance characteristics such that the resonance frequency of longitudinal vibration is 200 Hz and the resonance frequency of bending vibration is 205 Hz,
The resonance frequency of both vibrations as seen from the drive circuit 500 is ± 1 kHz
It suffices if it is within the range of z (about ± 0.5%).

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 electrodes 33a and 33c for electrically exciting the diaphragm 10 to flexural vibration are balanced with the protrusions 36 of the four corners of the diaphragm 10. Although provided at a portion corresponding to the portion 18, the number, position, and shape of the electrodes 33 provided separately are not limited thereto. For example, the electrodes 33 may be provided separately at positions as illustrated in FIGS.

In the example shown in FIG. 15, a substantially triangular electrode 33d formed at the corner of the piezoelectric element 30 (the same applies to the piezoelectric element 31 on the other side) where the projection 36 is provided, It is divided into the electrode 33e formed in the portion. When the electrodes are divided as described above, the capacitor 505 may be connected between the electrode 33d for electrically exciting the bending vibration and the drive circuit 500.

In the example shown in FIG. 16, the electrodes 33a and 33 formed at the two corners in the above embodiment are used.
Substantially triangular electrodes 33f and 33g are formed in place of c, and electrodes 33h are formed in other portions. Thus, the shape of the electrode is not limited to the rectangular shape, but may be the above-described triangular shape or another shape.

In the example shown in FIG.
Three electrodes 33ia, 33ib and an electrode 33j are formed on the upper side along the longitudinal direction. Here, the electrode 33i
The electrodes 33a and 33ib are formed on the piezoelectric element 30 on the protruding portion 36 side (upper side in the drawing) at substantially the center in the longitudinal direction and are divided. The electrode 33j is formed at other positions. 33ia and 33ib are smaller in width (up and down direction in the figure) than the electrode 33j. That is, the electrodes 33ia and 33ib are formed along the longitudinal direction with a small width on the protrusion 36 side, and the capacitor 505 is connected between the electrode 33ia and the drive circuit 500. On the other hand, the electrode 33ib is connected to the electrode 33 by the electric wire 160.
j. That is, in this modification, the electrode 33ia is an electrode for electrically exciting bending vibration, and the electrode 33j and the electrode 33ib are electrodes for electrically exciting longitudinal vibration, similarly to the electrode 33b in the above embodiment. ing.

When the electrodes are divided into various shapes, numbers, and positions as described above, an electrode for electrically exciting longitudinal vibration and an electrode for electrically exciting bending vibration are arranged in parallel with the drive circuit 500. , And a capacitor 505 may be connected between an electrode for exciting bending vibration and the drive circuit 500. Here, the electrode that electrically excites bending vibration is not induced by mechanical characteristics such as shape imbalance, but is directly caused by expansion and contraction of the piezoelectric element at the portion where the electrode is formed. 18 are formed in a portion where the
As shown in FIG. 3, electrodes 131, 132, 133, and 134 are respectively applied to each of approximately four divided portions on the rectangular piezoelectric element 130.
Also, when the piezoelectric element is provided, secondary flexural vibration can be generated electrically by the expansion and contraction of the piezoelectric element as shown by the arrow in the figure, and these electrodes 131, 132, 133, 13
4 can be said to electrically excite the bending vibration.
However, in this case, since a large longitudinal vibration cannot be excited, in the above-described embodiment and each modified example, an electrode for exciting the longitudinal vibration is formed in almost the entire region, and then a minute bending vibration is partially excited. That is, an electrode is formed.

(Modification 2) In the above-described embodiment, the capacitor 505 is connected between the drive circuit 500 and the electrodes 33a and 33c. Instead, as shown in FIG. The coil 510 may be connected. When connecting the coil 510 in this way,
As the capacitance of the coil 510, an equivalent circuit shown in FIGS. 20A and 20B is prepared in order to perform the same frequency adjustment as that of the capacitor 505, and the following equation is used for the coil 510 (= coil L
What is necessary is to use the value solved for the capacity (L3) of 3).

(Equation 2) Note that, between the drive circuit 500 and the electrodes 33a and 33c,
Both the capacitor 505 and the coil 510 may be connected.

(Modification 3) In the above-described embodiment, a drive circuit 500 having an oscillation circuit 504 is separately provided to apply a drive voltage to the piezoelectric elements 30 and 31, that is, so-called separately excited oscillation is performed. Alternatively, the piezoelectric elements 30 and 31 may be driven by self-excited oscillation. For example, FIG.
As shown in FIG. 1, a Colpitts-type drive circuit using the diaphragm 10 as a vibrator may be configured.

(Modification 4) In the above-described embodiment, the case where the diaphragm 10 having the characteristic that the resonance frequency of the longitudinal vibration (primary) is slightly lower than the resonance frequency of the bending vibration (secondary) is used. As described above, the resonance frequency of the longitudinal vibration may be slightly higher than the resonance frequency of the bending vibration depending on the size of the diaphragm 10. When using the diaphragm 10 having such characteristics, the capacitor 50
5 and the coil 510 may be connected between electrodes other than the electrodes (electrodes 33a and 33c) for electrically exciting the bending vibration, that is, between the electrode 33b and the drive circuit 500. When the diaphragm 10 having such characteristics is employed, the elliptical trajectory of the protrusion 36 due to the displacement of the diaphragm 10 is reversed, and the direction in which the rotor 100 is driven is shown in FIG.
It is counter-clockwise (reverse direction to the above embodiment). Therefore, when the diaphragm 10 having such characteristics is adopted, it is necessary to change the positional relationship between the rotor 100 and the diaphragm 10 from the above-described embodiment according to a required driving direction.

(Modification 5) 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 6) In the above-described embodiment, an example was described in which the piezoelectric actuator A1 was employed as a drive mechanism of a calendar display mechanism mounted on a wristwatch, but the present invention is not limited to this. However, the present invention 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 A1 can be made thinner and smaller, and can be driven with high efficiency. Therefore, the piezoelectric actuator A1 is suitable as an actuator mounted on a battery-driven portable device or the like.

(Variation 7) In the above-described embodiment, the vibration plate 10 vibrates to rotate the rotor 100 that is in contact with the protrusion 36. However, the present invention is not limited to this. It is also possible to apply the present invention to a linear actuator that drives a driven object linearly.

[0072]

As described above, according to the present invention,
More stable driving can be realized while using a driving circuit having a simple configuration.

[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 side sectional view showing a schematic configuration of the wristwatch.

FIG. 3 is a side 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 side sectional view showing a diaphragm which is a component of the piezoelectric actuator.

FIG. 6 is a diagram showing a schematic drive configuration when a voltage is applied to a piezoelectric element of the diaphragm.

FIG. 7 is a view for explaining electrodes formed on a surface of a piezoelectric element of the vibration plate.

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 diagram for explaining a trajectory of a protrusion when the diaphragm vibrates.

FIG. 11 is a graph showing an example of a relationship between a vibration frequency of the diaphragm and impedance.

FIG. 12 is a diagram showing a drive configuration of the piezoelectric actuator.

FIG. 13 is a graph showing a relationship between a vibration frequency of a diaphragm including a capacitor and an impedance as viewed from a driving circuit of the piezoelectric actuator.

14A is a diagram showing an equivalent circuit of longitudinal vibration and bending vibration of the diaphragm, and FIG. 14B is a diagram showing an equivalent circuit of longitudinal vibration and bending vibration of the diaphragm including the capacitor. is there.

FIG. 15 is a view showing a modification of the piezoelectric actuator.

FIG. 16 is a view showing a modification of the piezoelectric actuator.

FIG. 17 is a view showing a modification of the piezoelectric actuator.

FIG. 18 is a view for explaining an electrode section in a modified example of the piezoelectric actuator.

FIG. 19 is a diagram showing a drive configuration of another modification of the piezoelectric actuator.

20A is a diagram showing an equivalent circuit of longitudinal vibration and bending vibration of a diaphragm in another modification of the piezoelectric actuator, and FIG. 20B is a diagram illustrating longitudinal vibration and bending vibration of the diaphragm including a coil. 3 is a diagram showing an equivalent circuit of FIG.

FIG. 21 is a diagram showing a configuration of a self-excited oscillation circuit using the diaphragm of the piezoelectric actuator as a vibrator.

[Explanation of symbols]

Reference numeral 10: diaphragm, 11: support member, 30, 31: piezoelectric element, 33, 33a, 33b, 33c, 33d, 33
e, 33f, 33g, 33h, 33i, 33j... electrodes, 36... protrusions, 100... rotor, 103.
Base plate, 500: drive circuit, 504: oscillation circuit, 50
5. Capacitor, 510 Coil, A1 Piezoelectric actuator

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hidehiro Akabane 3-3-5 Yamato, Suwa City, Nagano Prefecture Inside Seiko Epson Corporation (72) Inventor Takeshi Takeshi 3-3-5 Yamato Suwa City, Nagano Prefecture Seiko Epson (72) Inventor Kunihiko Takagi 3-5-5 Yamato, Suwa-shi, Nagano F-term (reference) in Seiko Epson Corporation 2F082 AA00 BB02 DD01 DD10 EE02 EE03 EE05 EE06 FF01 HH00 5H680 AA00 AA06 AA19 BB01 BB11 BB15 BC02 CC02 CC10 DD01 DD15 DD23 DD28 DD39 DD53 DD67 DD73 DD82 DD92 DD95 EE10 EE12 FF16 FF17 FF26 FF32 GG02 GG27

Claims (10)

[Claims] A vibrating plate, comprising: a support; a plate-shaped piezoelectric element having a longitudinal direction; and a vibrating plate supported so as to be able to vibrate with respect to the support; A contact portion to be brought into contact with a drive target; a plurality of divided electrode portions provided on the piezoelectric element; and a drive circuit for supplying a drive voltage of a single frequency to each of the electrode portions in parallel. By supplying the drive voltage to the piezoelectric element through each of the electrode portions, the piezoelectric element is vibrated to cause the vibration plate to vibrate in the longitudinal direction and in the width direction orthogonal to the longitudinal direction. And a piezoelectric actuator that drives the driven object by the displacement of the abutting portion caused by the vibration, wherein the driving circuit and the bending vibration among the electrode units connected in parallel to the driving circuit are generated. Exciting electrically A frequency adjusting unit provided between the electrode unit or the other electrode unit provided for adjusting a frequency of a driving voltage supplied from the driving circuit; and By performing frequency adjustment according to the difference between the resonance frequency of the predetermined order of the longitudinal vibration of the diaphragm and the resonance frequency of the predetermined order of the bending vibration, the predetermined order of the diaphragm including the frequency adjustment unit is adjusted. A longitudinal vibration of the piezoelectric actuator and a resonance frequency of the bending vibration of the predetermined order are substantially matched. 2. The method according to claim 1, wherein the electrode section to which the driving voltage adjusted by the frequency adjusting unit is supplied is provided near a position where the amplitude of the bending vibration generated in the diaphragm becomes a maximum value. The piezoelectric actuator according to claim 1. 3. The piezoelectric actuator according to claim 1, wherein the frequency adjusting unit has a capacitor or a coil. 4. The driving circuit according to claim 1, further comprising a self-excited oscillation circuit using the diaphragm as a vibrator, and supplying a driving voltage having a frequency oscillated from the self-excited oscillation circuit. Item 4. The piezoelectric actuator according to any one of Items 1 to 3. 5. The piezoelectric actuator according to claim 1, wherein the vibration plate has a structure in which the piezoelectric element and a reinforcing plate are stacked. 6. A timepiece comprising: the piezoelectric actuator according to claim 1; and a ring-shaped calendar display wheel driven by the piezoelectric actuator. 7. A portable device comprising: the piezoelectric actuator according to claim 1; and a battery that supplies power to the piezoelectric actuator. 8. A vibrating plate having a support, a plate-shaped piezoelectric element having a longitudinal direction, and vibrating against the support, and one end in the longitudinal direction of the vibrating plate. A contact portion provided and brought into contact with a driving target; a plurality of divided electrode portions provided on the piezoelectric element; and a drive circuit for supplying a drive voltage of a single frequency to each of the electrode portions in parallel. And between the drive circuit and any one of the electrode portions or the other electrode portions provided for electrically exciting the bending vibration among the electrode portions connected in parallel to the drive circuit. And a frequency adjustment means for adjusting the frequency of the drive voltage supplied from the drive circuit,
By supplying the driving voltage to the piezoelectric element through the respective electrode portions, the piezoelectric element is vibrated to cause the vibration plate to generate the longitudinal vibration and the bending vibration swinging in the width direction orthogonal to the longitudinal direction. Generating a piezoelectric actuator that drives the driven object by the displacement of the abutting portion caused by the vibration, the method comprising: measuring impedance characteristics of the diaphragm; and A step of obtaining a resonance frequency of a predetermined order of the longitudinal vibration of the diaphragm and a resonance frequency of a predetermined order of the bending vibration; and a step of obtaining a resonance frequency of the longitudinal vibration and a resonance frequency of the bending vibration obtained from the impedance characteristic. The resonance frequency of the longitudinal vibration of the predetermined order and the resonance frequency of the bending vibration of the predetermined order are substantially equal to each other based on Determining the frequency adjustment means for performing frequency adjustment according to a difference between a resonance frequency of a predetermined order of longitudinal vibration of the diaphragm and a resonance frequency of a predetermined order of the bending vibration. Characteristic piezoelectric actuator design method. 9. The design of the piezoelectric actuator according to claim 8, wherein the frequency adjusting means is a capacitor or a coil, and the step of determining the frequency adjusting means determines a capacity of the capacitor or the coil. Method. 10. A support, comprising: a plate-shaped piezoelectric element having a longitudinal direction, a vibrating plate supported so as to be able to vibrate relative to the support, and one end in the longitudinal direction of the vibrating plate. A contact portion provided and brought into contact with a driving target; a plurality of divided electrode portions provided on the piezoelectric element; and a drive circuit for supplying a drive voltage of a single frequency to each of the electrode portions in parallel. And between the drive circuit and any one of the electrode portions or the other electrode portions provided for electrically exciting the bending vibration among the electrode portions connected in parallel to the drive circuit. And a frequency adjustment means for adjusting the frequency of the drive voltage supplied from the drive circuit,
By supplying the driving voltage to the piezoelectric element through the respective electrode portions, the piezoelectric element is vibrated to cause the vibration plate to generate the longitudinal vibration and the bending vibration swinging in the width direction orthogonal to the longitudinal direction. Generating a piezoelectric actuator that drives the driven object by the displacement of the abutting portion caused by the vibration, wherein an impedance characteristic of the diaphragm is obtained, and the impedance of the diaphragm obtained from the impedance characteristic is obtained. Based on the resonance frequency of the predetermined order of the longitudinal vibration and the resonance frequency of the predetermined order of the bending vibration, the predetermined order of the longitudinal vibration and the predetermined order of the longitudinal vibration indicated in the impedance characteristic of the diaphragm including the frequency adjusting means. A resonance frequency of a predetermined order of longitudinal vibration of the diaphragm and a resonance frequency of a predetermined order of the bending vibration such that the resonance frequencies of the bending vibration substantially coincide with each other. Determining the frequency adjusting means for performing frequency adjustment according to the difference between the driving circuit and the bending vibration of the electrode portions connected in parallel to the driving circuit. A step of connecting the electrode to the electrode portion provided for exciting the electrode.