WO2016152224A1 - Piezoelectric actuator and electronic timepiece - Google Patents

Abstract

Provided are a piezoelectric actuator with good drive efficiency and an electronic timepiece such that factors that would cause the peak resonance frequency of the piezoelectric actuator to fluctuate are reduced, thereby facilitating drive frequency setting and device installation. The piezoelectric actuator is provided with: two piezoelectric components 1a, 1b that are arranged in a V-shape so as to form a predetermined angle therebetween and deform when a voltage is applied thereto; a base 2 that is disposed on the side where the two piezoelectric components 1a, 1b intersect with each other and secures the intersection-side ends of the two piezoelectric components 1a, 1b; a thin plate-like elastic member 4 that bridges the expanding sides of the two piezoelectric components 1a, 1b and is fixed to the expanding side ends of the two piezoelectric components 1a, 1b; and a transmission part 43 that is disposed on the center part of the elastic member 4 in the direction in which the elastic member 4 bridges the two piezoelectric components 1a, 1b.

Description

Piezoelectric actuator and electronic timepiece

The present invention relates to a piezoelectric actuator and an electronic timepiece.

Conventionally, a piezoelectric actuator including a displacement element (piezoelectric element) that expands and contracts when a voltage is applied is known.
The piezoelectric actuator, for example, causes mechanical resonance by applying a predetermined voltage to the piezoelectric element, and the transmission unit (columnar protrusion) operates so as to draw an elliptical orbit by this vibration. And the operation | movement target object press-contacted to a transmission part is moved (driving) by the elliptical motion of this transmission part (for example, refer patent document 1).

In such a piezoelectric actuator, in order to transmit the elliptical motion of the transmission unit to the operation target, it is necessary to cause the transmission unit to press and contact the operation target to generate a frictional force. Japanese Patent Application Laid-Open No. 2009-71903 discloses a configuration including a pressurizing unit that applies pressure using a coil spring.

The piezoelectric element has a resonance peak when a voltage having a predetermined frequency is applied. For this reason, in order to efficiently resonate the piezoelectric element, it is necessary to adjust the driving frequency when applying a voltage to the piezoelectric element to a frequency band where the resonance reaches a peak.
However, in the case of a configuration in which a spring such as a coil spring is brought into contact with the piezoelectric actuator and the piezoelectric actuator is pressed by a spring force as in the conventional piezoelectric actuator described in Patent Document 1, the spring comes into contact with the piezoelectric actuator. The frequency band in which the resonance of the piezoelectric element reaches a peak also deviates from the peak frequency band in the case of the piezoelectric actuator alone.
For this reason, even if the drive frequency is adjusted for a single piezoelectric actuator, the drive frequency must be adjusted again in consideration of the shift in the resonance frequency due to the addition of the spring in the assembled state in which the spring or the like is attached. There is a problem.

In addition, the conventional piezoelectric actuator has a pressurizing mechanism constituted by a member different from the piezoelectric actuator, and the pressurizing mechanism applies a pressure from one end side to the other end side of the piezoelectric actuator. Yes. For this reason, the operation object with which the transmission part of the piezoelectric actuator comes into contact can be arranged only on the side where the pressure is applied, and the force generated by the expansion / contraction operation of the piezoelectric element cannot be fully utilized. There is also a problem that is bad.

Furthermore, when the piezoelectric actuator is pressurized from the outside, the table for fixing the piezoelectric element itself is also deformed when the piezoelectric element resonates. For this reason, when the piezoelectric actuator is incorporated in the apparatus, it is necessary to fix the base at a location where the amount of deformation is small, and there is a problem that the installation position and installation method of the piezoelectric actuator are restricted.

An object of the present invention is to provide a piezoelectric actuator in which a drive frequency can be easily set and an electronic timepiece having the actuator.

In order to solve the above problems, the piezoelectric actuator according to the present invention is:
Two displacement members which are arranged in a V shape so as to form a predetermined angle and which are displaced by applying a voltage;
A table which is arranged on the intersection side of the two displacement members and fixes the end portion on the intersection point of the two displacement members;
A thin plate-like elastic member that is stretched over the expansion side of the two displacement members and fixed to the end of the two displacement members on the expansion side;
A transmission portion provided at a central portion in the bridging direction to the two displacement members in the elastic member;
It is characterized by having.

It is a perspective view of the piezoelectric actuator in a 1st embodiment. It is a disassembled perspective view of the piezoelectric actuator of FIG. FIG. 2 is a front view of the piezoelectric actuator of FIG. 1 and an operation target operated by the piezoelectric actuator. 2 is a graph showing an example of a waveform of an applied voltage applied to the piezoelectric actuator of FIG. 1. (A) to (e) are image diagrams schematically showing results of simulating the movement of the piezoelectric actuator when the voltage having the waveform shown in FIG. 4 is applied to the piezoelectric element of FIG. It is a figure which shows the result of having simulated the locus | trajectory of the transmission part at the time of applying a voltage to the piezoelectric actuator of FIG. It is a top view which shows the state which integrated the piezoelectric actuator in 1st Embodiment in the electronic timepiece. It is a front view of the piezoelectric actuator in 2nd Embodiment, and the operation target object operated by this. It is a figure which shows the result of having simulated the locus | trajectory of the transmission part at the time of applying a voltage to the piezoelectric actuator of FIG. It is a front view of one modification of a piezoelectric actuator, and an operation subject operated by this. It is a front view of one modification of a piezoelectric actuator, and an operation subject operated by this. It is a front view of one modification of a piezoelectric actuator, and an operation subject operated by this. It is a front view of one modification of a piezoelectric actuator, and an operation subject operated by this.

[First Embodiment]
Hereinafter, a first embodiment of a piezoelectric actuator and an electronic timepiece according to the invention will be described with reference to FIGS. 1 to 7.
The embodiments described below are given various technically preferable limitations for carrying out the present invention, but the scope of the present invention is not limited to the following embodiments and illustrated examples.

FIG. 1 is a perspective view of a piezoelectric actuator according to the present embodiment, FIG. 2 is an exploded perspective view of the piezoelectric actuator, and FIG. 3 is a front view of the piezoelectric actuator and an operation target operated by the piezoelectric actuator.
The piezoelectric actuator 100 according to the present embodiment operates, for example, a disk hand (for example, a disk hand 510 shown in FIG. 7) constituting a date mechanism of a wristwatch that is an electronic timepiece or the like, and a hand moving mechanism that operates a pointer. The operation target R is a rotor or the like connected to a gear or the like constituting such a mechanism. Note that the target to be operated by the piezoelectric actuator 100 is not limited to the example illustrated here.

As shown in FIGS. 1 to 3, the piezoelectric actuator 100 of the present embodiment is fixed to two piezoelectric elements 1 ( piezoelectric elements 1a and 1b) as displaceable displacement members and one end side of the piezoelectric elements 1a and 1b. 2, the elastic member 4 fixed to the other end side of the piezoelectric elements 1 a and 1 b, and a transmission portion 43 provided on the elastic member 4.
In the following, the term “piezoelectric element 1” includes the piezoelectric element 1a and the piezoelectric element 1b.

In the present embodiment, the two piezoelectric elements 1a and 1b are displacement elements that undergo displacement such as expansion and contraction by applying a voltage.
The piezoelectric element 1 includes, for example, a laminated type using piezoelectric ceramics.
The piezoelectric element 1 may be any element that can be expanded and contracted by applying a voltage, vibrates, and causes the transmission unit 43 described later to elliptically move by this vibration (resonance). As long as it exists, it is not limited to this, What was illustrated above may be sufficient.
The two piezoelectric elements 1 a and 1 b are arranged in a V shape so as to form a predetermined angle, and the ends of the two piezoelectric elements 1 a and 1 b on the intersection point side are fixed to the base 2.

The base 2 of the present embodiment has a substantially isosceles triangular shape when viewed from the front, and has two inclined surfaces 2a and 2b.
The base 2 is arranged on the intersection side of the two piezoelectric elements 1a and 1b, and the end of one end side (intersection side) of the piezoelectric element 1a is fixed to the inclined surface 2a via the adhesive layer 3. . In addition, an end of one end side (intersection side) of the piezoelectric element 1b is fixed to the inclined surface 2b with an adhesive layer 3 interposed therebetween.
In the embodiment 2, the angle between the inclined surfaces 2a and 2b is approximately 90 degrees, and the angle between the two piezoelectric elements 1a and 1b fixed to the inclined surfaces 2a and 2b is approximately 90 degrees. It has become.

When the piezoelectric actuator 100 is mounted inside the case 501 (see FIG. 7) of the electronic timepiece 500, the base 2 is fixed to a ground plate or a substrate (not shown) by screws or the like.
That is, in this embodiment, since a spring or the like constituting the pressurizing mechanism is not disposed under the table 2, the bottom surface, which is one surface of the table 2, can be directly fixed on the ground plate, the substrate, or the like. The table 2 is not deformed even when driven.
When the base 2 vibrates and deforms when the piezoelectric actuator 100 is driven, it is necessary to devise a fixing position and a holding method in consideration of deformation of the base 2 and the like. In this respect, in the present embodiment, such a consideration is unnecessary, and thus the fixing position of the base 2 is not limited, and the degree of freedom of the installation position of the piezoelectric actuator 100 is increased.

The elastic member 4 is a thin plate-like member that is stretched over the expanded side of the piezoelectric elements 1a and 1b, which are two displacement members, and is fixed to the end of the expanded side of the two piezoelectric elements 1a and 1b.
The elastic member 4 is a member that can be elastically deformed, and is, for example, a leaf spring formed of a thin plate-like iron material or the like. In addition, the material etc. which form an elastic member are not specifically limited.

In the present embodiment, the elastic member 4 is a straight portion 41 in which the central portion in the extending direction between the two piezoelectric elements 1a and 1b (the longitudinal direction of the thin plate-like elastic member 4 and the lateral direction in FIG. 3) is linear. On both sides of the straight portion 41, there are inclined portions 42a and 42b which are inclined at substantially the same gradient as the inclined surfaces 2a and 2b of the table 2, respectively.
An end of the other end side (expansion side) of the piezoelectric element 1a is fixed to the surface of the inclined portion 42a facing the base 2 with the adhesive layer 5 interposed therebetween. In addition, an end of the other end side (expansion side) of the piezoelectric element 1b is fixed to the surface of the inclined portion 42b on the side facing the base 2 with the adhesive layer 5 interposed therebetween.

In the elastic member 4, a transmission portion 43 is provided at a substantially central portion (that is, a substantially central portion of the straight portion 41) in the bridging direction between the two piezoelectric elements 1 a and 1 b.
In this embodiment, the transmission part 43 is formed in a protruding shape so as to protrude to the side opposite to the side on which the base 2 is provided by bending a part of the thin plate-like elastic member 4. .
In the present embodiment, the transmission unit 43 operates so as to draw an elliptical orbit by vibrations of the piezoelectric elements 1a and 1b (hereinafter referred to as “elliptical motion”).

The transmission unit 43 abuts on the surface of the operation target R in a state assembled in the electronic timepiece 500 (see FIG. 7) or the like, and transmits movement such as vibration of the piezoelectric actuator 100 to the operation target R.
In the present embodiment, the elastic member 4 itself provided with the transmission portion 43 is a leaf spring, and the elastic member 4 presses the transmission portion 43 against the operation target R (that is, an upward arrow in FIG. 3). It functions as a pressurizing mechanism that urges in the direction indicated by. Thereby, the transmission part 43 is always in contact with the operation target R in a state where pressure is applied, and when the transmission part 43 performs an elliptical motion as will be described later, the elliptical motion is applied to the movement target R by a frictional force. Communication is possible.

In addition, the transmission part 43 should just be a thing of the shape which can transmit a motion to the operation target object R, The shape, formation method, etc. are not specifically limited.
For example, in FIG. 1 and the like, a substantially mountain-shaped transmission portion 43 is provided in the front view over the width direction of the thin plate-like elastic member 4 (that is, the direction orthogonal to the longitudinal direction of the elastic member 4). The transmission part may be a weight-like or columnar protrusion provided at the substantially central part in the longitudinal direction and the width direction of the elastic member 4.
Further, the transmission portion 43 shown in FIG. 1 and the like is hollow only by bending the thin plate-like elastic member 4, but a rigid body having a high specific gravity is formed in the hollow portion of the projection-like transmission portion 43. It may be solid by embedding.
In this way, by arranging a rigid body or the like having a high specific gravity in the transmission unit 43, the longitudinal direction of the transmission unit 43 when the piezoelectric element 1 vibrates (resonates) and the case where the transmission unit 43 is left hollow. The amount of displacement in the lateral direction can be increased.

As shown in FIG. 3, the two piezoelectric elements 1a and 1b are provided with electrodes (not shown), and voltage applying means 11 (voltage applying means 11a and 11b) are electrically connected to the electrodes, respectively. Yes.
The voltage applying means 11a and 11b apply an alternating voltage to the piezoelectric elements 1a and 1b.
The voltage applying means 11a and 11b of the present embodiment input AC voltages with shifted phases to the two piezoelectric elements 1a and 1b, respectively, so that vibrations in the vertical and horizontal directions ( Resonance) and the combination thereof excites elliptical vibration in the transmission portion 43 provided at the center of the elastic member 4.
Further, vibration (resonance) caused by applying a voltage to the piezoelectric element 1 has a peak in a predetermined frequency band, and the closer the driving frequency of the voltage applied to the piezoelectric element 1 is to the predetermined frequency band, the piezoelectric element 1. Accordingly, the speed of the elliptical motion of the transmission unit 43 (that is, the driving speed of the piezoelectric actuator 100) and the thrust (that is, the driving force of the piezoelectric actuator 100) increase accordingly.
For this reason, the voltage applying means 11a and 11b apply a voltage to the two piezoelectric elements 1a and 1b at a driving frequency in a frequency band where the resonance of the piezoelectric elements 1a and 1b peaks.
Further, the higher the voltage value of the voltage applied by the voltage applying means 11a and 11b, the greater the vibration (resonance) generated in the piezoelectric element 1, and the speed of the elliptical motion of the transmission portion 43 (that is, the driving speed of the piezoelectric actuator 100). ) And thrust (that is, driving force of the piezoelectric actuator 100) also increases.
For this reason, the voltage values applied by the voltage applying means 11a and 11b are appropriately adjusted so as to have a desired speed (driving speed) and thrust (driving force) according to the application of the piezoelectric actuator 100 and the like.

FIG. 4 is a graph showing an example of a waveform of an alternating voltage applied to the piezoelectric elements 1a and 1b by the voltage applying means 11a and 11b.
A waveform CH1 indicated by a solid line in FIG. 4 is a waveform example of an AC voltage applied to the piezoelectric element 1a by the voltage applying unit 11a, and a waveform CH2 indicated by a one-dot chain line is a piezoelectric element 1b by the voltage applying unit 11b. It is an example of a waveform of the alternating voltage applied with respect to.
As shown in FIG. 4, a predetermined phase difference is provided between the waveform CH1 and the waveform CH2.

Here, the movement of the piezoelectric actuator 100 of the present embodiment will be described with reference to FIGS. 5 (a) to 5 (e).
5A to 5E show the movement of the piezoelectric actuator 100 when an AC waveform voltage having a phase difference as shown in FIG. 4 is applied to the piezoelectric elements 1a and 1b of the present embodiment. It is the image figure which showed the result of having simulated typically.
From the initial state shown in FIG. 5A, when a voltage is first applied to the piezoelectric element 1a by the voltage applying means 11a, the piezoelectric element 1a contracts and deforms as shown in FIG. The elastic member 4 is pulled toward the piezoelectric element 1a (left side in FIG. 5B), and the entire piezoelectric actuator 100 is tilted toward the piezoelectric element 1a side (left side in FIG. 5B). Next, when a voltage is applied to the piezoelectric element 1b by the voltage applying means 11b, the piezoelectric element 1b contracts and deforms, and as shown in FIG. 5C, the initial state shown in FIG. 5D, the elastic member 4 is pulled toward the piezoelectric element 1b (the right side in FIG. 5D), and the entire piezoelectric actuator 100 is moved to the piezoelectric element 1b. Tilt to the side (right side in FIG. 5B). When a voltage is again applied to the piezoelectric element 1a by the voltage applying means 11a, the piezoelectric element 1a contracts and deforms, and as shown in FIG. 5 (e), gradually shown in FIG. 5 (a). After the state close to the initial state, as shown in FIG. 5B, the entire piezoelectric actuator 100 tilts toward the piezoelectric element 1a (left side in FIG. 5B).
As described above, the voltage application means 11a and 11b provide a phase difference with respect to the piezoelectric elements 1a and 1b and alternately apply an alternating voltage, whereby the piezoelectric actuator 100 is vibrated in the vertical direction and the horizontal direction, and is elastic. Elliptical vibration is excited in the central part of the member 4 and the transmission part 43 moves elliptically.

FIG. 6 is a diagram illustrating a result of simulating the locus of the transmission unit 43 when an AC waveform voltage having a phase difference as described above is applied to the piezoelectric elements 1a and 1b of the piezoelectric actuator 100. FIG. .
In FIG. 6, an ellipse indicated by a solid line is a plot of the motion of the apex (indicated by a black dot in the diagram of FIG. 6) of the transmission portion 43 of the piezoelectric actuator 100 shown at the lower left of FIG. 6.
As shown in FIG. 6, when an AC waveform voltage having alternating phase differences is applied to the piezoelectric elements 1a and 1b by the voltage applying means 11a and 11b, the piezoelectric elements 1a and 1b are alternately expanded and contracted and vibrated. As a result, the transmission portion 43 provided at the central portion of the elastic member 4 connected to the piezoelectric elements 1a and 1b largely elliptically moves in an elliptical orbit.

FIG. 7 is a diagram showing a state in which the piezoelectric actuator 100 is mounted inside a case 501 of an electronic timepiece 500 (for example, a wristwatch) provided with hands 502 and the like.
As described above, when the piezoelectric actuator 100 is mounted inside the case 501 (see FIG. 7) of the electronic timepiece 500, the base 2 is fixed on a ground plate or a substrate (not shown) by screws or the like.
In addition, the position etc. in which the stand 2 is provided are not limited to the example of illustration.

FIG. 7 illustrates a case where the disk needle 510 that displays the date by exposing the numbers from the date window 503 is driven to rotate by the piezoelectric actuator 100 of the present embodiment.
As shown in FIG. 7, the transmission unit 43 of the piezoelectric actuator 100 is in contact with an operation target R such as a rotor, and the operation target R is rotated by the elliptical motion of the transmission unit 43. ing. A first gear 512 is attached to a rotating shaft (not shown) of the operation target R, and this first gear 512 is not shown (not shown) provided on the rotating shaft 511 of the disc needle 510. Gear).
On the disc needle 510, numbers representing numbers (numbers from 1 to 31) are sequentially written along the periphery. When the elliptical motion is transmitted to the operation target R by the transmission unit 43 of the piezoelectric actuator 100 and the operation target R rotates, the disk needle 510 rotates about the rotation shaft 511 through the first gear 512. The numbers exposed from the date window 503 are switched so that the date can be displayed as appropriate.
The configuration in which the disk needle 510 is rotated by the piezoelectric actuator 100 is not limited to the example illustrated here. For example, more gears may be interposed between the piezoelectric actuator 100 and the disk needle 510.
Further, the object to be rotationally driven by the piezoelectric actuator 100 is not limited to the disk needle 510. For example, the piezoelectric actuator 100 of this embodiment may be used as a drive source for rotating the pointer 502.

Next, the operation of the piezoelectric actuator 100 and the electronic timepiece 500 including the same according to the present embodiment will be described.

In this embodiment, when assembling the piezoelectric actuator 100, the piezoelectric elements 1a and 1b are fixed on the base 2 having the inclined surfaces 2a and 2b. Specifically, the end of the intersection side of the piezoelectric element 1a is fixed on the inclined surface 2a via the adhesive layer 3, and the intersection side of the piezoelectric element 1b is interposed on the inclined surface 2b via the adhesive layer 3. Fix the end of the.
Further, the elastic member 4 having the transmission portion 43 is disposed on the expansion side of the piezoelectric elements 1a and 1b, and an adhesive is applied to the lower side surface (the lower surface in FIG. 3 and the like) of one inclined portion 42a of the elastic member 4. The end of the expansion side of the piezoelectric element 1a is fixed via the layer 5, and the expansion of the piezoelectric element 1b via the adhesive layer 5 on the lower side of the other inclined part 42b (the lower side in FIG. 3 etc.). Secure the open end.
Further, voltage applying means 11a and 11b are connected to the electrodes of the piezoelectric elements 1a and 1b, respectively.
Thereby, the piezoelectric actuator 100 is completed.
When the piezoelectric actuator 100 is incorporated in the electronic timepiece 500, the piezoelectric actuator 100 is disposed at a position where the transmission portion 43 is in contact with the surface of the operation target R such as a rotor, and the base 2 is attached to the ground plate in the case 501 with screws or the like. Fix on the substrate.

When the piezoelectric actuator 100 is operated, an AC waveform voltage having a phase difference as shown in FIG. 4 is applied to the piezoelectric elements 1a and 1b from the voltage applying means 11a and 11b with a predetermined driving frequency and voltage, for example. Apply by value.
Thus, for example, as shown in FIGS. 5A to 5E, the piezoelectric elements 1a and 1b alternately expand and contract, and are provided at the central portion of the elastic member 4 connected to the piezoelectric elements 1a and 1b. An elliptical motion as shown in FIG. 6 is excited in the transmitted portion 43.
The transmission unit 43 is in a pressurized state that is always pressed against the surface of the operation target R by the spring force of the elastic member 4, and the elliptical motion of the transmission unit 43 is performed by the frictional force. Is transmitted to. Thereby, the operation target R (for example, the rotor) moves (rotates) in a predetermined direction.

As described above, according to the present embodiment, the piezoelectric actuator 100 includes the two piezoelectric elements 1 which are arranged in a V shape so as to form a predetermined angle and are displaceable displacement members. The ends of the intersections of the two piezoelectric elements 1a and 1b are fixed to the base 2, and the ends of the two piezoelectric elements 1a and 1b on the expansion side are fixed to the thin plate-like elastic member 4. In addition, a transmission portion 43 that abuts on the surface of the operation target R is provided at a substantially central portion in the length direction of the elastic member 4.
Thus, since the transmission part 43 is provided in the thin-plate-like elastic member 4 having a spring property, the transmission part 43 can be operated without an additional pressurizing mechanism such as a spring for applying a separate pressure. It can be pressed against the surface of R to provide a pressurized state. For this reason, the number of parts constituting the piezoelectric actuator 100 can be reduced, and a small and simple structure can be obtained.
Further, when the driving frequency of the voltage applied from the voltage applying means 11a, 11b to the piezoelectric elements 1a, 1b deviates from the resonance frequency band of the piezoelectric elements 1a, 1b, the driving speed and driving force of the piezoelectric actuator 100 are reduced, and the piezoelectric actuator 100 Drive efficiency is reduced. For this reason, it is preferable that the drive frequency is fixed to the frequency without being changed once it is adjusted to the drive frequency corresponding to the resonance frequency band of the piezoelectric elements 1a and 1b. However, when a separate pressurization mechanism for pressing the transmission unit against the surface of the operation target is provided, the drive frequency can be set afterwards in consideration of individual differences (manufacturing variation) of the springs of the pressurization mechanism. Adjustments need to be made.
In this regard, in this embodiment, the elastic member 4 constituting the piezoelectric actuator 100 functions as a pressurizing mechanism that pressurizes the transmission portion 43. For this reason, fluctuations in the resonance frequency of the piezoelectric elements 1a and 1b due to external elements can be suppressed, and it is not necessary to set or adjust the driving frequency afterwards, and the piezoelectric actuator 100 can be incorporated into the electronic timepiece 500 or the like. It can be done easily.
Further, in the present embodiment, since a spring or the like constituting the pressurizing mechanism is not arranged under the base 2, the bottom surface, which is one surface of the base 2, can be directly fixed on the ground plate or the substrate, and the piezoelectric actuator 100 can be The table 2 is not deformed even when driven. Thereby, when the piezoelectric actuator 100 is incorporated in the electronic timepiece 500 or the like, the fixing method or the fixing position of the base 2 is not limited, and the degree of freedom of the installation position of the piezoelectric actuator 100 is expanded.

[Second Embodiment]
Next, a second embodiment of a piezoelectric actuator and an electronic timepiece including the same according to the present invention will be described with reference to FIGS. Since this embodiment is different from the first embodiment only in the elastic member, the following description will focus on differences from the first embodiment.

FIG. 8 is a front view of the piezoelectric actuator and the operation object operated by the piezoelectric actuator.
As shown in FIG. 8, the piezoelectric actuator 200 includes two piezoelectric elements 1a and 1b similar to those in the first embodiment, and a table 2 that fixes the end of the intersection of the piezoelectric elements 1a and 1b. .
Further, a thin plate-like elastic member 6 is bridged on the expansion side of the piezoelectric elements 1a and 1b. The elastic member 6 is a leaf spring formed of, for example, a thin plate-like iron material as in the first embodiment.

In the present embodiment, the elastic member 6 is a straight portion 61 in which the central portion in the extending direction between the two piezoelectric elements 1a and 1b (the longitudinal direction of the thin plate-like elastic member 6 and the lateral direction in FIG. 8) is linear. On both sides of the straight portion 61, there are inclined portions 62a and 62b which are inclined at substantially the same gradient as the inclined surfaces 2a and 2b of the table 2, respectively.
An end of the other end side (expansion side) of the piezoelectric element 1a is fixed to the surface of the inclined portion 62a on the side facing the base 2 with the adhesive layer 5 interposed therebetween. Further, the other end side (expanded side) end portion of the piezoelectric element 1b is fixed to the surface of the inclined portion 62b on the side facing the base 2 with the adhesive layer 5 interposed therebetween.

The elastic member 6 has a thin plate-like shape on the side where the base 2 is provided, which is the substantially central portion (that is, the substantially central portion of the straight portion 61) in the bridging direction between the two piezoelectric elements 1a and 1b. A transmission portion 63 formed in a protruding shape by bending a part of the elastic member 6 is provided.
In the present embodiment, the transmission unit 63 operates so as to draw an elliptical orbit by vibrations of the piezoelectric elements 1a and 1b (hereinafter referred to as “elliptical motion”).

In the present embodiment, the piezoelectric actuator 200 is configured such that the operation target R is disposed on the lower side (lower side in FIG. 8) of the elastic member 6 in a state assembled in an electronic timepiece or the like.
And the transmission part 63 contact | abuts to the surface of the operation target object R from the upper side (upper side in FIG. 8), and transmits motion, such as vibration of the piezoelectric actuator 200, to the operation target object R.
Also in the present embodiment, as in the first embodiment, the elastic member 6 itself provided with the transmission portion 63 is a leaf spring, and the elastic member 6 moves the transmission portion 63 to the operation target R. It functions as a pressurizing mechanism that urges in the pressing direction (ie, the direction indicated by the downward arrow in FIG. 8). Thereby, the transmission part 63 is always in contact with the operation target R in a state where pressure is applied. When the transmission part 63 performs an elliptical motion as described later, the elliptical motion is applied to the movement target R by a frictional force. Communication is possible.

In addition, the transmission part 63 should just be a thing of the shape which can transmit a motion to the operation | movement target object R, The shape, formation method, etc. are not specifically limited similarly to 1st Embodiment.

FIG. 9 is a diagram illustrating a result of simulating the locus of the transmission unit 63 when an AC waveform voltage having a phase difference as described above is applied to the piezoelectric elements 1 a and 1 b of the piezoelectric actuator 200.
In FIG. 9, an ellipse indicated by a solid line is a plot of the movement of the apex (indicated by a black dot in the drawing of FIG. 9) of the transmission portion 63 of the piezoelectric actuator 200 shown at the lower left of FIG.
As shown in FIG. 9, when an AC waveform voltage having a phase difference alternately applied to the piezoelectric elements 1a and 1b by the voltage applying means 11a and 11b, the piezoelectric elements 1a and 1b alternately expand and contract. Thereby, the transmission part 63 provided in the center part of the elastic member 6 connected to the piezoelectric elements 1a and 1b largely elliptically moves in an elliptical orbit.

Since other configurations are the same as those described in the first embodiment, the same members are denoted by the same reference numerals and description thereof is omitted.

Next, the operation of the piezoelectric actuator 200 and the electronic timepiece including the same according to the present embodiment will be described.

In this embodiment, when assembling the piezoelectric actuator 200, the piezoelectric elements 1a and 1b are fixed on the base 2 having the inclined surfaces 2a and 2b, and the transmitting portion 63 is provided on the expansion side of the piezoelectric elements 1a and 1b. The elastic member 6 having the elastic member 6 is arranged, and the end portion on the expansion side of the piezoelectric element 1a is fixed to the lower side surface (lower surface in FIG. 8) of one inclined portion 62a of the elastic member 6 through the adhesive layer 5. Then, the end portion on the expansion side of the piezoelectric element 1b is fixed to the lower side surface (the lower surface in FIG. 8) of the other inclined portion 62b via the adhesive layer 5.
Further, voltage applying means 11a and 11b are connected to the electrodes of the piezoelectric elements 1a and 1b, respectively.
Thereby, the piezoelectric actuator 200 is completed.
When the piezoelectric actuator 200 is incorporated into an electronic timepiece, the piezoelectric actuator 200 is disposed at a position where the transmission unit 63 is in contact with the surface of the operation target R such as a rotor, and the base 2 or the substrate in the case 501 is attached to the base 2 with screws or the like. Fix it finely.
In the present embodiment, as shown in FIG. 8, the operation target R is disposed below the transmission unit 63, and the transmission unit 63 contacts the operation target R from above while being pressurized.

When the piezoelectric actuator 200 is operated, for example, an AC waveform voltage having a phase difference is applied from the voltage applying means 11a and 11b to the piezoelectric elements 1a and 1b at a predetermined driving frequency and voltage value.
Thereby, the piezoelectric elements 1a and 1b alternately expand and contract and vibrate alternately, and an elliptical motion as shown in FIG. 9 is caused in the transmission part 63 provided at the center of the elastic member 6 connected to the piezoelectric elements 1a and 1b. Excited.
The transmission unit 63 is in a pressurized state that is always pressed against the surface of the operation target R by the spring force of the elastic member 6, and the elliptical motion of the transmission unit 63 is caused by the frictional force. Is transmitted to. Thereby, the operation target R (for example, the rotor) moves (rotates) in a predetermined direction.
Since other points are the same as those described in the first embodiment, description thereof is omitted.

As described above, according to the present embodiment, the following effects can be obtained in addition to the same effects as those of the first embodiment.
That is, in this embodiment, the transmission part 63 is provided on the lower side of the elastic member 6 (the lower side in FIG. 8, the inner side of the piezoelectric actuator 200), and the operation target R is disposed on the lower side of the transmission part 63. Is done.
For this reason, compared with the case where the operation target R is disposed on the upper side of the transmission unit, the space for providing the piezoelectric actuator 200 can be reduced, and it can be easily accommodated in a small case.
In this embodiment, the transmission part 63 that moves elliptically is provided on the thin plate-like elastic member 6. Thus, when the transmission part 63 is arranged on a thin leaf spring, even if the position of the transmission part 63 in contact with the operation target R is slightly changed, the elliptical motion in the transmission part 63 is not significantly affected, and the piezoelectric elements 1a and 1b are not affected. Due to the vibration (resonance), the transmission unit 63 operates in a largely elliptical locus (see the elliptical trajectory shown in FIG. 9). For this reason, even if the transmission part 63 is provided on the lower surface of the thin plate-like elastic member 6, the driving efficiency of the piezoelectric actuator 200 does not decrease, and the piezoelectric actuator 200 can be reduced in size and space-saving while maintaining the driving efficiency. Can do.

In addition, although embodiment of this invention was described above, it cannot be overemphasized that this invention is not limited to this embodiment, A various deformation | transformation is possible in the range which does not deviate from the summary.

For example, in each of the above embodiments, the angle formed between the inclined surfaces 2a and 2b of the base 2 is approximately 90 degrees, and the angle formed between the two piezoelectric elements 1a and 1b fixed to the inclined surfaces 2a and 2b is approximately. Although the case of 90 degrees is illustrated, the angle formed by the two piezoelectric elements 1a and 1b is not limited to approximately 90 degrees.
For example, as shown in FIG. 10, the slopes of the inclined surfaces 21a and 21b of the table 21 are made gentle so that the angle formed by the two piezoelectric elements 1a and 1b fixed to the inclined surfaces 21a and 21b is an acute angle of more than 90 degrees. Also good. In this case, the elastic member 7 also has a shape corresponding to the shape of the base 21, and specifically, the slopes of the inclined parts 72 a and 72 b provided on both sides of the straight part 71 are the slopes of the inclined surfaces 21 a and 21 b of the base 21. It becomes moderate corresponding to.
As described above, when the angle formed by the two piezoelectric elements 1a and 1b is an acute angle, the vertical displacement of the ellipse tends to increase when the locus of the elliptical motion of the transmission unit 73 is viewed. Thereby, the thrust (driving force) of the piezoelectric actuator is improved.

Further, for example, as shown in FIG. 11, the slopes of the inclined surfaces 22a and 22b of the base 22 are made steep, and the angle formed by the two piezoelectric elements 1a and 1b fixed to the inclined surfaces 22a and 22b is more than 90 degrees. It may be an obtuse angle. In this case, the elastic member 8 also has a shape corresponding to the shape of the base 22, and specifically, the inclination of the inclined portions 82 a and 82 b provided on both sides of the straight portion 81 is the gradient of the inclined surfaces 22 a and 22 b of the base 22. Suddenly in response to.
As described above, when the angle formed by the two piezoelectric elements 1a and 1b is an obtuse angle, the elliptical lateral displacement tends to increase when the locus of the elliptical motion of the transmission unit 83 transmission unit 83 is viewed. . Thereby, the speed (drive speed) of the piezoelectric actuator is improved.

In FIGS. 10 and 11, as shown in the second embodiment, the operation object R is disposed below the elastic member (the lower side in FIGS. 10 and 11 and the inner side of the piezoelectric actuator). Although an example is illustrated, the relationship between the angle formed by the two piezoelectric elements 1a and 1b and the locus of the elliptical motion of the transmission unit is such that the operation target R as shown in the first embodiment is located above the elastic member. The same applies to the case of being arranged on the upper side in FIGS. 10 and 11 and the outer side of the piezoelectric actuator, and the same effect can be obtained.

Moreover, in each said embodiment, although the case where a transmission part was formed by performing a bending process to a thin-plate shaped elastic member was illustrated, the method of forming a transmission part is not limited to this.
For example, as shown in FIG. 12, the elastic member 9 having the straight portion 91 and the inclined portions 92a and 92b is almost in the crossing direction with respect to the piezoelectric elements 1a and 1b (the longitudinal direction of the elastic member 9 and the lateral direction in FIG. 12). The transmitting portion 93 may be configured by attaching a protruding member formed as a separate member by a rigid body having a high specific gravity or the like to the central portion (that is, substantially the central portion of the straight portion 91). The material or the like for forming the protruding member is not particularly limited as long as it has rigidity, wear resistance, and the like. The method for attaching the protruding member to the elastic member 9 is not particularly limited, and for example, a method such as adhesion fixing or spot welding can be used.
Thus, when the transmission part 93 is comprised by the protrusion-shaped member formed with the rigid body etc. with high specific gravity, the piezoelectric element 1 is compared with the case where a thin plate-shaped elastic member is bent and a transmission part is formed. It is possible to increase the amount of displacement in the vertical direction and the horizontal direction of the transmission portion 93 when oscillates (resonates).
In FIG. 12, as shown in the first embodiment, an example in which the operation target R is disposed on the upper side of the elastic member (the upper side in FIG. 12 and the outer side of the piezoelectric actuator) is illustrated. Even when the transmission portion 93 formed by pasting the protrusion-shaped member is disposed on the lower side of the elastic member (lower side in FIG. 12, inner side of the piezoelectric actuator) as shown in the second embodiment. Similar effects can be obtained.

In each of the above embodiments, the transmission portion 43 is located above the elastic member 4 (upper side in FIG. 3 and the like, outside the piezoelectric actuator 100) or the transmission portion 63 is located below the elastic member 6 (lower side in FIG. 8). 200, and the operation target R is located above the elastic member 4 (upper side in FIG. 3, etc., outside the piezoelectric actuator) corresponding to the transmission parts 43, 63 or below the elastic member 6 (lower side in FIG. 8). Although the case where it arrange | positions in any one of the side and the inner side in a piezoelectric actuator) was illustrated, arrangement | positioning of the operation target R which operate | moves when a transmission part and a transmission part contact | abut is not limited to this.

For example, as shown in FIG. 13, a transmission part is provided on each of the upper side (transmission part 93 in FIG. 13) and the lower side (transmission part 94 in FIG. 13) of the elastic member 9 to correspond to each transmission part 93, 94. The operation objects R1 and R2 that operate when the transmission units 93 and 94 come into contact with each other may be disposed at the positions where the transmission is performed.
In this case, the transmission part 93 and the transmission part 94 are arranged on the front and back with the elastic member 9 as a leaf spring interposed therebetween, and the operation objects R1 and R2 are in contact with the transmission part 93 and the transmission part 94, respectively. The transmission unit 93 is pressurized against the operation target R1, and the transmission unit 94 is pressurized against the operation target R2.
When the piezoelectric actuator has such a configuration, when the piezoelectric elements 1a and 1b vibrate (resonate) when voltage is applied, the transmission unit 93 provided on the upper side of the elastic member 9 and the lower side of the elastic member 9 are provided. Each of the provided transmission portions 94 performs an elliptical motion.
The transmission unit 93 is in press contact with the operation target R1 in an elliptical motion state, whereby the elliptical motion is transmitted to the operation target R1, and the operation target R1 moves (rotates) in a predetermined direction. In addition, the transmission unit 94 is pressed against the operation target R2 in an elliptical motion state, whereby the elliptical motion is transmitted to the operation target R2, and the operation target R2 moves (rotates) in a predetermined direction.
As described above, when the transmission unit 93 and the transmission unit 94 are arranged above and below the elastic member 9 (front and back, that is, outside and inside of the piezoelectric actuator), the two operation objects R1 and R2 are simultaneously moved by one piezoelectric actuator. It is possible to operate, and it is possible to improve the driving efficiency of the piezoelectric actuator by reducing as much as possible the loss of idling without the transmission portion being in contact with the operation target.
Although FIG. 13 illustrates the case where the transmission parts 93 and 94 formed by attaching the protruding members are arranged above and below the elastic member 9 (front and back, that is, outside and inside the piezoelectric actuator), The configuration of the portions 93 and 94 is not limited to this, and for example, as shown in the first embodiment and the second embodiment, a hollow transmission portion is formed by bending a thin plate-like elastic member. Even if formed, the same effect can be obtained.

Further, in each of the above embodiments, the voltage application means 11a and 11b respectively input AC voltages with shifted phases to the two piezoelectric elements 1a and 1b, whereby the piezoelectric elements 1a and 1b are longitudinally and laterally input. In the above example, a driving method for generating elliptical vibrations and exciting elliptic vibrations in the transmission portion 43 provided in the center of the elastic member 4 by the combination thereof is illustrated. However, the driving method for driving the piezoelectric actuator is not limited thereto. .
For example, by inputting an AC voltage to only one of the two piezoelectric elements 1 a and 1 b, the piezoelectric element 1 is expanded and contracted, and the expanded and contracted movement is transmitted to the other piezoelectric element 1 via the elastic member 4 and the base 2. By doing so, the other piezoelectric element 1 may be vibrated in conjunction with this movement.
In this case, the piezoelectric elements 1a and 1b vibrate with their phases shifted from each other, thereby generating vibrations in the vertical direction and the horizontal direction, and the combination can excite elliptical vibration in the transmission unit 43.

Further, in each of the above embodiments, the case where the two displacement members are the two piezoelectric elements 1a and 1b as the displacement elements that are displaced by applying a voltage is exemplified, but the two displacement members are at least one. It is sufficient that the element is a displacement element that is displaced by applying a voltage, and both need not be displacement elements.
For example, as described above, when an AC voltage is applied to only one of the displacement members to cause expansion / contraction motion, and this expansion / contraction motion is transmitted to the other displacement member to be passively vibrated, voltage The displacement member on the driven side to which no voltage is applied does not have to be a displacement element such as a piezoelectric element, and may be an elastic member such as a displaceable spring.
In this case as well, the other displacement member to which no voltage is applied vibrates in conjunction with each other, so that the two displacement members vibrate while out of phase with each other, thereby generating vertical and horizontal vibrations, By the combination, elliptical vibration can be excited in the transmission unit 43.

Further, in each of the above embodiments, the case where the piezoelectric actuator is incorporated in the electronic timepiece 500 is exemplified, but the target to which the piezoelectric actuator is applied is not limited to the electronic timepiece 500.
For example, you may apply the piezoelectric actuator 100 to terminal devices, such as a pedometer, a heart rate meter, an altimeter, and a barometer.

Although several embodiments of the present invention have been described above, the scope of the present invention is not limited to the above-described embodiments, but includes the scope of the invention described in the claims and the equivalents thereof.

The present invention can be widely used for a piezoelectric actuator including a displacement member such as a piezoelectric element and an electronic device such as an electronic timepiece including the piezoelectric actuator.

DESCRIPTION OF SYMBOLS 1a, ab Piezoelectric element 2 Base 2a, 2b Inclined surface 4 Elastic member 11 Voltage application means 43 Transmission part 42a, 42b Inclined part 100 Piezoelectric actuator 500 Electronic timepiece 501 Case R Operation object

Claims (6)

1. Two displacement members which are arranged in a V shape so as to form a predetermined angle and which are displaced by applying a voltage;
   A table which is arranged on the intersection side of the two displacement members and fixes the end portion on the intersection point of the two displacement members;
   A thin plate-like elastic member that is stretched over the expansion side of the two displacement members and fixed to the end of the two displacement members on the expansion side;
   A transmission portion provided at a central portion in the bridging direction to the two displacement members in the elastic member;
   A piezoelectric actuator comprising:
2. 2. The piezoelectric actuator according to claim 1, wherein the transmission portion is provided on a surface of the elastic member on the side where the two displacement members are fixed.
3. 2. The piezoelectric actuator according to claim 1, wherein the transmission unit is provided on a surface of the elastic member on which the two displacement members are fixed and a surface on the opposite side.
4. A piezoelectric actuator according to claim 1;
   An operation object that is operated by the piezoelectric actuator; a case that houses the piezoelectric actuator and the operation object;
   Electronic watch with
5. A piezoelectric actuator according to claim 2;
   An operation object that is operated by the piezoelectric actuator; a case that houses the piezoelectric actuator and the operation object;
   Electronic watch with
6. A piezoelectric actuator according to claim 3;
   An operation object that is operated by the piezoelectric actuator; a case that houses the piezoelectric actuator and the operation object;
   Electronic watch with

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