JPH10308543A - Piezoelectric vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the input power of a piezoelectric transducer and increase the boosting rate, by arraying both vibrators in parallel to the longitudinal direction, and expanding, compressing and vibrating the vibrators. SOLUTION: A first vibrator 10 and a second vibrator 20 are connected to each other by a connection part 30. An input side electrode 11 is formed on the entire surface of the first vibrator 10 and a large driving power is supplied to the first vibrator 10, thus generating longitudinal vibration of the first vibrator 10. This longitudinal vibration is transmitted to the second vibrator 20, thus generating longitudinal vibration of the second vibrator 20, too. By this longitudinal vibration, a boosted voltage is taken out between electrodes 21 and 22. Since the second vibrator 20 as a whole functions for output, a voltage boosted at a high impedance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a piezoelectric transformer for boosting or the like, a piezoelectric filter, a vibrating gyroscope, and the like. In particular, the present invention relates to a piezoelectric vibrator which causes a plurality of vibrators to expand and contract. About the child.

[0002]

2. Description of the Related Art FIG. 7 is a perspective view showing a vibrator used in a conventional piezoelectric transformer. In this piezoelectric transformer, an input portion 2 of a flat plate type vibrator 1 made of a piezoelectric material is polarized in a thickness direction, and input electrodes 3 are provided on both front and back surfaces. The drive voltage applied to the input electrode 3 excites the longitudinal vibration caused by the electromechanical coupling coefficient K31 in the transverse effect mode. In the power generation unit 4, the output side electrode 5 is provided on the end face, and a voltage boosted according to the impedance is extracted from the output side electrode 5 by the electromechanical coupling coefficient K33 in the longitudinal effect mode.

[0003]

However, the conventional piezoelectric transformer shown in FIG. 7 has the following problems. (1) Since the input-side electrode 3 is formed only in a region approximately half the planar shape of the vibrator 1, the input power for driving given to the piezoelectric vibrator is limited, and driving with a large power cannot be performed. . (2) Similarly, since there is a limit in increasing the length of the output section in the vertical direction, there is a limit in increasing the output impedance, and there is a limit in the voltage boost rate of the piezoelectric transformer. (3) Since the frequency of the longitudinal vibration is uniquely determined by the size of the vibrator 1, there is no selectivity of the driving frequency. (4) Since the output side electrode 5 is formed at a portion where the amplitude of the longitudinal vibration is large, the stress acting on the lead wire connected to the output side electrode 5 is large, and disconnection or the like is likely to occur.

The present invention has been made to solve the above-mentioned conventional problems, and can be driven by a large power, can increase a boosting rate when used as a piezoelectric transformer, has selectivity in a driving frequency, and has a vibration. It is an object of the present invention to provide a piezoelectric vibrator that can prevent a disconnection by connecting a lead wire to a node portion of the piezoelectric vibrator.

[0005]

According to the present invention, there is provided a first vibrator made of a piezoelectric material and having a longitudinal dimension longer than a width dimension, and the first vibrator made of a piezoelectric material. A coupling part that couples the two vibrators on a line that connects nodes of vibration of the two vibrators in a state where the two vibrators are arranged with their longitudinal directions parallel to each other; A drive power supply unit that applies AC power to a drive-side electrode formed on the first vibrator to expand and contract both the first vibrator and the second vibrator, and generates power by the expansion and contraction vibration of the second vibrator And an output-side electrode for extracting power.

For example, the first vibrator is one in which longitudinal vibration due to the lateral effect is excited by the AC power applied to the drive side electrode, and the second vibrator is from the output side electrode due to the longitudinal effect. The increased power generation voltage is taken out.

In the above, both the vibrators expand and contract in a mode in which the second vibrator contracts in the longitudinal direction when the first vibrator expands in the longitudinal direction by the driving power of a predetermined frequency applied to the driving side electrode. Vibrate.

Alternatively, the two vibrators are stretched and vibrated in a mode in which the second vibrator extends in the longitudinal direction when the first vibrator extends in the longitudinal direction by the driving power of a predetermined frequency applied to the driving side electrode. Will do.

In the above, at least one of the input side electrode and the output side electrode is formed at a node of vibration of the vibrator, and a lead wire is connected to the electrode at the node of vibration. Is preferred.

In the present invention, a plurality of vibrators having a long longitudinal direction such as a rectangle and an oval are used, for example, two vibrators are used. Are connected by a connecting portion.

The two vibrators generate longitudinal vibration (stretching vibration) in a mode in which one expands while the other contracts, or longitudinal vibration (stretching vibration) in a mode in which both vibrators simultaneously expand and contract. Is driven to produce

In this piezoelectric vibrator, since the vibrator on the drive side and the vibrator on the output side (detection side) are separate bodies, the input side electrode can be formed in a large area on the first vibrator. Input power can be increased. On the output side, for example, the impedance can be increased, and when used as a piezoelectric transformer, an output with a high boosting rate can be obtained.

In addition, since the first and second vibrators can be driven in two modes: a mode in which the first and second vibrators expand and contract in opposite phases, and a mode in which the first and second vibrators expand and contract simultaneously, they can be driven at different driving frequencies. Use frequency band can be widened.

Further, since each of the vibrators has a vibration node at the center in a plane, if a lead wire is connected to the vibration node, no stress is generated at the connection portion of the lead wire. In addition, disconnection of the lead wire can be prevented.

[0015]

FIG. 1 is a perspective view showing a piezoelectric vibrator of the present invention used as a piezoelectric transformer, and FIG.
(A) and (B) of FIG. 3 are plan views showing vibration modes. The piezoelectric transformer shown in FIG. 1 has a first vibrator 10 and a second vibrator 20 of a flat plate type formed of a piezoelectric material such as a piezoelectric ceramic.
Both vibrators 10 and 20 have a rectangular plane, and the vibrators 10 and 20 have the same shape and dimensions.

In the first vibrator 10, the center point O10 serving as the rectangular center of gravity serves as a node of vibration, and in the second vibrator 20, the center point O20 serving as the rectangular center of gravity serves as a node of vibration. The two transducers 10 and 20 are connected to each other with the long sides parallel to each other.
Are connected to each other. This connecting portion 30 is provided in the first
Extends on a line connecting a center point O10 serving as a node of vibration of the vibrator 10 and a center point O20 serving as a node of vibration of the second vibrator 20.

The first vibrator 10 has a thickness direction in the dielectric polarization direction (see the arrow) in the entire region, and the second vibrator 20 has a dielectric polarization direction in the long side direction (Y direction) in the entire region. Yes (see arrow). An input electrode 11 is formed on almost the entire surface of the first vibrator 10, and a ground electrode 12 facing the input electrode 11 is formed on almost the entire back surface. An AC drive voltage is applied between the input side electrode 11 and the ground electrode 12 from an AC drive power supply unit 13.

In the second vibrator 20, an output electrode 21 is formed on one end face in the longitudinal direction, and a ground electrode 22 is formed on the other end face. Output electrode 21 and ground electrode 2
2 have a small area and face each other and have a long facing distance, so that a high impedance output section is formed. Therefore, a boosted output voltage (Vout) is obtained between the lead wire 23 connected to the output electrode 21 and the ground potential.

FIGS. 3A and 3B schematically show the vibration modes of the piezoelectric vibrator. When an AC drive voltage of a predetermined frequency is applied from the AC drive power supply unit 13 to the input side electrode 11, the first vibrator 10 polarized in the thickness direction is applied to the first vibrator 10.
Longitudinal vibration (flat stretching vibration) is excited by the transverse effect mode of the electromechanical coupling coefficient K31. First vibrator 10
In the longitudinal vibration, distortion occurs in the longitudinal direction (Y direction) and the width direction (X direction) according to the Poisson's ratio. The distortion in the width direction (X direction) at this time extends from the coupling portion 30 to the second vibrator 20, and the second vibrator 20 is also excited in the longitudinal direction.

The vibration mode of the entire piezoelectric vibrator at this time is, as shown in FIG. 3A, when the first vibrator 10 extends in the vertical direction (Y direction). Is a mode in which the first oscillator 1 contracts in the vertical direction (Y direction).
The mode in which the zero and second vibrators 20 expand and contract in opposite phases, and the second vibrator 20 is extended when the first vibrator 10 extends in the vertical direction (Y direction) as shown in FIG. There is a mode in which the first vibrator 10 and the second vibrator 20 expand and contract in the same phase so that the vibrators 20 extend in the vertical direction at the same time.

The vibration mode shown in FIG.
The resonance frequency is different from the vibration mode shown in FIG.
As shown in FIG. 4, the frequency (frequency) f1 in the vibration mode shown in FIG. 3A is lower than the frequency (frequency) f2 in the vibration mode shown in FIG. 3B. FIG.
In both the vibration mode shown in FIG. 3A and the vibration mode shown in FIG. 3B, the node of vibration of the first vibrator 10 is the center point O10, and the node of vibration of the second vibrator 20 is also the same. The center point O20. That is, since the first vibrator 10 and the second vibrator 20 are coupled with each other at the nodes of vibration, vibrations in the modes shown in FIGS. It becomes easy to excite. In the second vibrator 20,
The output electrode 21 and the ground electrode 2 are provided at the ends in the vertical direction (Y direction).
2, the output impedance is high. Therefore, a boosted voltage generated by the electromechanical coupling coefficient K33 in the longitudinal effect mode is output between the electrodes 21 and 22.

In the equivalent circuit diagram shown in FIG. 2, Cd1 is the braking capacity of the first vibrator 10 on the input side, Cd2 is the braking capacity of the second vibrator 20 on the output side, m1, s1,
r1 is the equivalent mass, equivalent stiffness, equivalent resonance resistance, m2, s2, r2 of the piezoelectric element constituting the first vibrator 10.
Is the equivalent mass of the piezoelectric element constituting the second vibrator 20,
Equivalent stiffness and equivalent resonance resistance. A1 is a mechanical constant of the first vibrator 10, and A2 is a mechanical constant of the second vibrator 20. The coupling part 30 is shown in the center of FIG. The equivalent stiffness of the coupling portion 30 is expressed by the Poisson's ratio between the first vibrator 10 and the second vibrator 20 and
It is determined according to requirements such as the structure of the coupling portion 30.

In the piezoelectric transformer constituted by the piezoelectric vibrator shown in FIG. 1, the coupling resistance of the coupling portion 30 is relatively small as shown in the equivalent circuit shown in FIG.
It is easy to excite the vibration of the mode as shown in (B), and as a result, the input impedance can be reduced. FIG.
Since the resonance mode (natural frequency) differs between the vibration mode shown in FIG. 3A and the vibration mode shown in FIG. 3B as f1 and f2, the working frequency band can be widened. Also, the first
Since the entire vibrator 10 functions as a vibrator on the driving side, the input-side electrode 11 can be formed with a larger area than the first vibrator 10. Therefore, the input power applied to the first vibrator 10 can be increased. Since the second vibrator 20 functions as a vibrator on the output side as a whole, the electrodes 21 and 22 on the output side can be formed on both end surfaces in the longitudinal direction, for example, as shown in FIG. Therefore, it is possible to increase the output impedance by reducing the braking capacitance Cd2 and increase the boost ratio as a transformer.

FIG. 5 is a perspective view showing another embodiment of the piezoelectric vibrator. In FIG. 5, an input electrode 11 is formed on the back surface of the first vibrator 10, and an AC drive power supply unit 13 is connected. A ground electrode 12 is formed on the surface of the first vibrator 10. This first vibrator 1
At 0, the light is polarized in the thickness direction between the ground electrode 12 and the input electrode 11. The ground electrode 12 extends to the peripheral portion of the surface of the second vibrator 20 and serves as a ground electrode 12a on the second vibrator 20 side. An output electrode 21 extending in the Y direction is formed at the center of the surface of the second vibrator 20. The second vibrator 20 is polarized in the width direction (X direction) between the ground electrode 12a and the output electrode 21.

In FIG. 5, all the electrodes of both the first vibrator 10 and the second vibrator 20 pass through the center point O10, which is a node of vibration, and the center point O20. Therefore, the AC drive power supply unit 13, the output unit, and the lead wire 23 for setting the ground potential can all be connected to the center point O10 and the center point O20. Therefore, the connection portion of the lead wire serves as a node of vibration, and no stress is applied.

FIG. 6A is a plan view showing an example of the supporting device of the piezoelectric vibrator shown in FIGS. 1 and 5, and FIG. 6B is a side view thereof. In the piezoelectric vibrator shown in FIGS. 1 and 5, the first vibrator 10 is used for driving, and the input side electrode 11 is formed on almost the entire surface, and a large driving force is applied to the first vibrator 10. It has become. Therefore, the vibration distortion applied to the first vibrator 10 and the second vibrator 20 during driving becomes considerably large, and the internal stress increases.
The vibrators 10 and 20 may be damaged.

Therefore, in the support device shown in FIG. 6, both end faces in the longitudinal direction of each of the vibrators 10 and 20 are supported by elastic bodies. The piezoelectric vibrator is supported by an insulating support 44 provided on the support 40.
Support walls 41, 41 are provided at both ends of the support base 40,
Screws 42, 42,... Are screwed on the respective support walls 41, 41, and elastic bodies 43, 43 are provided on the screws 42, 42. The elastic bodies 43 are made of rubber or the like. The tightening force of the screw 42 is adjusted, and the elastic body 43
The center in the width direction of both the first vibrator 10 and the second vibrator 20 can be elastically pressed with an appropriate force.

By this elastic pressing, when the first vibrator 10 and the second vibrator 20 are driven with a large vibration distortion, the distortion is suppressed so as not to be excessive, and the breakage of the vibrator is prevented. it can. Further, a structure may be used in which a leaf spring is used as the elastic body 43 and the vibrators 10 and 20 are sandwiched between the leaf springs. Alternatively, the elastic body 43 or the leaf spring may be formed of a conductive material and pressed against the electrodes 21 and 22 shown in FIG. 1, and the elastic body 43 or the leaf spring may be used instead of the lead wire.

In the examples shown in FIGS. 1 and 5, the first
Vibrator 10 and second vibrator 20 are provided one by one,
The two vibrators 10 and 20 are connected by a connecting portion 30 to form a set of two vibrators. For example, the first vibrator 20 is provided on both sides of the second vibrator 20 via the connecting portion 30. A structure in which three vibrators to which the vibrators 10 are respectively connected is a set, or a set of four vibrators in which the first vibrator 10 and the second vibrator 20 are alternately connected via the coupling portion 30 It may be a structure. Alternatively, a plurality of transducers may be joined. In this case, adjacent vibrators may vibrate in the same phase as each other, or adjacent vibrators may vibrate in opposite phases.

Further, the vibrator of the present invention can be used as a piezoelectric filter. In this case, as shown in FIG. 4, the pass band of the frequency can be widened. Further, this piezoelectric vibrator can be used as a vibrating gyroscope. In this case, when a bending force due to the Coriolis force acts in a direction orthogonal to the vibration direction of the second vibrator 20,
What is necessary is just to detect this bending force.

[0031]

As described above, the piezoelectric vibrator of the present invention
Driving can be performed with a large driving force, and the driving frequency can have selectivity. Further, the boosting rate when used as a piezoelectric transformer can be increased.

It is also possible to connect a lead wire to the node of the vibration so as to prevent disconnection.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example in which a piezoelectric transformer is constituted by a piezoelectric vibrator of the present invention;

2 is an equivalent circuit diagram of the piezoelectric vibrator shown in FIG. 1,

FIGS. 3A and 3B are plan views each showing a vibration mode;

FIG. 4 is a diagram showing frequencies in each vibration mode shown in FIG. 3;

FIG. 5 is a perspective view of a piezoelectric vibrator constituting a piezoelectric transformer according to a second embodiment of the present invention;

FIG. 6A is a plan view of a supporting device for a piezoelectric vibrator,
(B) is a side view thereof,

FIG. 7 is a perspective view of a conventional piezoelectric transformer,

[Description of Signs] 10 First vibrator 11 Input side electrode 12 Ground electrode 13 AC drive power supply unit 20 Second vibrator 21 Output side electrode 22 Ground electrode 30 Coupling unit

Claims (5)

[Claims] 1. A first vibrator formed of a piezoelectric material and having a longitudinal dimension longer than a width dimension thereof, and a second vibrator formed of a piezoelectric material and having the same shape as the first vibrator. A vibrator, a connecting portion for connecting the two vibrators on a line connecting nodes of vibration of the two vibrators in a state where the two vibrators are arranged with their longitudinal directions parallel to each other, and a first vibrator. A drive power supply unit that applies AC power to the drive-side electrode to expand and contract both the first oscillator and the second oscillator, and an output-side electrode that extracts power generated by the expansion and contraction of the second oscillator. A piezoelectric vibrator characterized by being provided with: 2. A first vibrator in which longitudinal vibration due to a lateral effect is excited by AC power applied to a drive side electrode, and a second vibrator from the output side electrode due to a longitudinal effect. 2. The piezoelectric vibrator according to claim 1, wherein the boosted power generation voltage is taken out. 3. The two vibrators expand and contract in a mode in which the second vibrator contracts in the longitudinal direction when the first vibrator extends in the longitudinal direction by driving power of a predetermined frequency applied to the driving-side electrode. The piezoelectric vibrator according to claim 1, wherein: 4. A drive power of a predetermined frequency applied to the drive-side electrode causes the two vibrators to expand and contract in a mode in which the second vibrator extends in the longitudinal direction when the first vibrator extends in the longitudinal direction. The piezoelectric vibrator according to claim 1, wherein: 5. An oscillator according to claim 1, wherein at least one of the input electrode and the output electrode is formed at a vibration node of the vibrator, and a lead wire is connected to the electrode at the vibration node. 5. The piezoelectric vibrator according to any one of 1 to 4.