JPH11214952A - Piezoelectric part and piezoelectric device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a piezoelectric part and a piezoelectric device which are easily connected to an external circuit that has low impedance, are easily miniaturized, have strong mechanical strength and have high reliability. SOLUTION: This piezoelectric part is configured by laminating piezoelectric layers 41 to 43 and electrode films 44 to 47. The layers 41 to 43 are laminated in the direction of their thickness with the films 44 and 45 between then, and the films 46 and 47 are formed on the top surface and the bottom surface respectively. The layer 41 is polarized in the direction from the film 44 toward the film 46, and the layer 42 is polarized in the direction from the film 44 toward the film 45 respectively. The layer 43 is polarized in the direction from the film 47 toward the film 45. The entire piezoelectric part vibrates in a length vibration mode in the direction that crosses perpendicularly to a polarizing direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric component,
The present invention relates to a piezoelectric component and a piezoelectric device used for an oscillator, a discriminator, a filter, and the like.

[0002]

2. Description of the Related Art Conventionally, three piezoelectric components 3 to 5 are connected like a ladder between an input terminal 1 and an output terminal 2 as in an electric equivalent circuit shown in FIG. A so-called ladder (ladder) filter 11 has been considered. The piezoelectric components 3, 4 are called series resonators, and the input terminals 1
And the output terminal 2 are connected in series. The piezoelectric component 5 is called a parallel resonator, and is connected between a signal line connecting the input terminal 1 and the output terminal 2 and the ground terminal G.

FIG. 12 shows an example of a specific configuration of the filter 11. The filter 11 includes piezoelectric components 3 to 5 and an insulating substrate 12 that supports the piezoelectric components 3 to 5. The piezoelectric components 3 to 5 are respectively provided on the front and back surfaces of the strip-shaped piezoelectric substrates 13 to 15 by vibrating electrodes 13 a and 13.
b, 14a, 14b, 15a, 15b. The thickness of each of the piezoelectric substrates 13 and 14 of the piezoelectric components 3 and 4 is set to be thicker than the piezoelectric substrate 15 of the piezoelectric component 5. These piezoelectric components 3 to 5 are composed of piezoelectric substrates 13 to 1
5 vibrates in a length vibration mode vibrating in the length direction.

[0004] The input terminal 1,
The output terminal 2, the ground terminal G, and the relay terminal 23 are formed. The piezoelectric component 3 is connected to the input terminal 1 at a substantially central portion of the vibrating electrode 13b using a flexible conductive adhesive.
It is adhered and held. The piezoelectric component 4 is bonded and held to the output terminal 2 at a substantially central portion of the vibration electrode 14b. The piezoelectric component 5 is adhered to and held by the ground terminal G at substantially the center of the vibration electrode 15b.

The vibration electrodes 13a, 14a and 15a of the piezoelectric components 3, 4 and 5 are electrically connected to the relay terminals 23 by bonding wires 25. The ladder-type filter 11 having the circuit configuration of FIG. 11 is formed on the insulating substrate 12 by the electrical connection of the piezoelectric components 3 to 5 by the conductive adhesive and the bonding wires 25 described above.

[0006]

Incidentally, in the conventional ladder-type filter 11, the ratio of the capacitance of the piezoelectric component 5 (parallel resonator) to the capacitance of the piezoelectric components 3 and 4 (series resonator). The larger the value is, the larger the insertion loss characteristics in the attenuation range and the better the filter characteristics. Therefore, the thickness of the piezoelectric substrate 15 of the parallel resonator 5 is set smaller than the thickness of the piezoelectric substrates 13 and 14 of the series resonators 3 and 4. However, when the thickness of the piezoelectric substrate 15 is reduced as described above, the mechanical strength of the parallel resonator 5 is reduced, and there is a problem that the filter 11 is easily broken when a shock or the like is applied from the outside.

In order to solve such a problem, as shown in FIG. 13, a filter 21 using a parallel resonator 5s using a spread vibration mode is used instead of the parallel resonator 5 using the length vibration mode. It is considered. This filter 2
1 is to make the piezoelectric substrate 22 square and make the vibrating electrode 22
The capacitance of the parallel resonator 5s is increased by increasing the facing area of the a and 22b. Therefore, the thickness of the piezoelectric substrate 22 can be increased by that much, so that its mechanical strength can be increased. However, in this case, since the shape of the parallel resonator 5s becomes large, there is a problem that the size of the filter 21 becomes large.

Further, the filter 11 shown in FIGS.
The series resonators 3 and 4 used for the vibrating electrodes 1
Since the areas of 3a, 13b and 14a, 14b are small and the capacitance formed therebetween is small, the impedance is high. For this reason, the input impedance and the output impedance of the filters 11 and 21 are increased, and there is a problem that it is difficult to achieve impedance matching when connecting the filters 11 and 21 to a semiconductor integrated circuit having a low input / output impedance.

Accordingly, an object of the present invention is to provide a small-sized piezoelectric component having low impedance, high mechanical strength and high reliability, and a piezoelectric device which can be easily matched with a low-impedance external circuit such as a semiconductor integrated circuit. To provide.

[0010]

In order to achieve the above object, a piezoelectric component according to the present invention comprises a plurality of piezoelectric layers and a plurality of electrode films stacked to form a laminate, and each of the piezoelectric members The polarization axes of the layers are aligned, and the polarization directions of adjacent piezoelectric layers are set to be opposite to each other, and the laminate vibrates in a length vibration mode in a direction orthogonal to the polarization direction of the piezoelectric layers. It is characterized by the following. Here, the plurality of electrode films provided in the stacked body are electrically connected, for example, via via holes.

With the above arrangement, as the number of laminated piezoelectric layers increases, the capacitance of the piezoelectric component increases.
The impedance of the piezoelectric component decreases. In addition, by increasing the number of piezoelectric layers, the mechanical strength of the piezoelectric component is increased.

Further, in the piezoelectric device according to the present invention, a plurality of piezoelectric layers and a plurality of electrode films are stacked to form a laminate, the polarization axes of the respective piezoelectric layers are aligned, and the piezoelectric layers of adjacent piezoelectric layers are aligned. The polarization directions are opposite to each other, and the laminate includes a piezoelectric component that vibrates in a length vibration mode in a direction orthogonal to the polarization direction of the piezoelectric layer.

As a specific example of the piezoelectric device, a series resonator and a parallel resonator are connected in a ladder shape between an input terminal and an output terminal, and at least one of a series resonator and a parallel resonator is connected. There is a piezoelectric device that employs the piezoelectric component. In this piezoelectric device, when the piezoelectric component is used as the series resonator, the capacitance of the series resonator increases as the number of stacked piezoelectric layers increases. Therefore, the impedance of the series resonator also becomes low, and impedance matching when connecting an external circuit having low impedance to the piezoelectric device becomes easy. On the other hand, when the piezoelectric component is used for the parallel resonator, the capacitance of the parallel resonator increases as the number of stacked piezoelectric layers increases. Therefore, the ratio of the capacitance of the parallel resonator to the capacitance of the series resonator increases, and when this piezoelectric device is used as a filter, the attenuation characteristics are improved.

[0014]

Embodiments of a piezoelectric component and a piezoelectric device according to the present invention will be described below with reference to the accompanying drawings. In each embodiment, a filter will be described as an example of a piezoelectric device, but it goes without saying that an oscillator, a discriminator, or the like may be used.

[First Embodiment, FIGS. 1 to 4] As shown in FIG. 1, a ladder-type filter 30 has an insulating substrate 36 made of an insulating material such as alumina, and is supported on the insulating substrate 36. And five piezoelectric components 31-35. Each of the piezoelectric components 31 to 35 is made of a piezoelectric ceramic, and each of the two piezoelectric components 31 and 33 is made up of three rectangular piezoelectric layers 41 to 43 as shown in FIG. Body layers 41 to 43 are stacked in the thickness direction with electrode films 44 and 45 interposed therebetween, and electrode films 46 and 47 are further formed on the upper surface and the lower surface, respectively, to form stacked body 40.

The three piezoelectric layers 41 to 43 are arranged such that their polarization axes are aligned and the polarization directions of the adjacent piezoelectric layers 41 to 43 are opposite to each other.
That is, the piezoelectric layers 41 to 43 are indicated by arrows P in FIG.
1, P2 and P3, respectively. The piezoelectric layer 41 is polarized in a direction from the electrode film 44 to the electrode film 46 in the thickness direction. The piezoelectric layer 42 is polarized in a direction from the electrode film 44 toward the electrode film 45 in the thickness direction. Further, the piezoelectric layer 43
Are polarized in the direction from the electrode film 47 to the electrode film 45 in the thickness direction. The length of the piezoelectric layers 41 to 43 is
It is determined based on the resonance frequency required for the piezoelectric components 31, 33.

An electrode film 45 disposed between the piezoelectric layers 42 and 43 and an electrode film 46 formed on the piezoelectric layer 41 are electrically connected by via holes 48. I have. The via hole 48 is formed between the piezoelectric layer 41 and the piezoelectric layer 4.
2 and is electrically insulated from the electrode film 44 disposed between them. The electrode film 44 provided between the piezoelectric layers 41 and 42 and the electrode film 47 formed on the piezoelectric layer 43 are electrically connected by via holes 49. . The via hole 49 is formed between the piezoelectric layer 42 and the piezoelectric layer 4.
3 and is electrically insulated from the electrode film 45 disposed between the first and third electrodes.

As the material of the piezoelectric layers 41 to 43, a piezoelectric ceramic, a piezoelectric single crystal, or the like is used. Electrode film 44-
47 is formed using a physical vapor deposition method (PVD method) such as vacuum deposition or sputtering, a coating method such as coating or printing, or an electroless and electrolytic plating method. When piezoelectric ceramics are used as the material of the piezoelectric layers 41 to 43, the polarization components applied during the polarization processing of the piezoelectric ceramics are applied to the electrode films 46 and 47 to manufacture the piezoelectric components 31 and 33. Can be easier. If necessary, a case (not shown) that covers the piezoelectric components 31 to 35 may be placed on the insulating substrate 36.

In the thus obtained laminated piezoelectric component, the electrode films 46 and 47 are used as input / output electrodes. When an electric signal is applied between the electrode films 46 and 45 and the electrode films 44 and 47, the piezoelectric layers 41 to 43 become piezoelectrically active.
That is, in the laminated piezoelectric component, voltages are applied in opposite directions to the piezoelectric layers 41 to 43 polarized in opposite directions by applying an electric signal to the electrode films 46 and 47. 43 try to expand and contract in the same direction. Therefore, the entire piezoelectric component is excited in the length vibration mode with the central portion of the laminate 40 as a node. Moreover, the laminated piezoelectric component has a length in a direction orthogonal to the polarization direction of the piezoelectric layers 41 to 43 (the direction indicated by arrows P1, P2 and P3), in other words, in the length direction of the piezoelectric component. Vibrates in vibration mode. Thus, the three piezoelectric layers 4
The laminated body 40 formed by 1 to 43 functions as a two-terminal piezoelectric component.

Returning to FIG. 1, the remaining three piezoelectric components 32,
Each of 34 and 35 is a strip-shaped piezoelectric substrate 5.
Vibrating electrodes 52a, 52b on the front and back surfaces of 2, 54 and 55,
54a, 54b and 55a, 55b are formed respectively. The piezoelectric substrates 52, 54 and 55 are polarized in the thickness direction and vibrate in a length vibration mode vibrating in the length direction.

On the other hand, an input terminal 61, an output terminal 62, a ground terminal 63, and relay terminals 65 and 66 are formed on the surface of the insulating substrate 36. The piezoelectric component 31 is adhered and held to the input terminal 61 at a substantially central portion of the electrode film 47 by a conductive adhesive having flexibility. The piezoelectric component 33 is adhered and held to the output terminal 62 at a substantially central portion of the electrode film 47 by a flexible conductive adhesive. The piezoelectric component 32 is adhered and held to the relay terminal 65 at a substantially central portion of the vibration electrode 52b by a conductive adhesive having flexibility. Piezoelectric component 34,
35 is made of a conductive adhesive having flexibility,
The vibrating electrodes 54b and 55b are adhered to and held by the ground terminal 63 at substantially the center.

The electrode film 46 of the piezoelectric component 31 and the piezoelectric component 3
4 are connected to the bonding wires 6 respectively.
8 is electrically connected to the relay terminal 65. Further, the vibration electrode 52a of the piezoelectric component 32, the electrode film 46 of the piezoelectric component 33, and the vibration electrode 55a of the piezoelectric component 35 are electrically connected to the relay terminals 66 by bonding wires 68, respectively.

The ladder-type filter 30 having the circuit configuration shown in FIG. 4 is electrically connected to the piezoelectric components 31 to 35 by the conductive adhesive and the bonding wires 68 described above.
Is configured. That is, the piezoelectric components (series resonators) 31 to 3
3 is connected in series between the input terminal 61 and the output terminal 62. Piezoelectric components (parallel resonators) 34 and 35 are connected between a signal line connecting the input terminal 61 and the output terminal 62 and the ground terminal 63.

In the ladder filter 30 having such a configuration, the input side piezoelectric component 31 and the output side piezoelectric component 33 connected to the input terminal 61 and the output terminal 62, respectively.
Has a multilayer structure composed of the piezoelectric layers 41 to 43 and the electrode films 44 to 47, the capacitance of the piezoelectric components 31 and 33 increases, and the impedance of the piezoelectric components 31 and 33 decreases. Therefore, impedance matching when connecting an external circuit having low impedance to the ladder-type filter 30 is facilitated. Further, the mechanical strength of the piezoelectric components 31 and 33 is increased by the multilayering of the piezoelectric layers 41 to 43.
Further, the capacitance of the piezoelectric components 31 and 33 can be changed by changing the number of stacked piezoelectric layers 41 to 43 and the electrode films 44 to 47. Therefore, by adjusting the number of stacked piezoelectric layers according to the input / output impedance of the external circuit to which the filter 30 is connected, impedance matching with the external circuit can be easily achieved.

[Second Embodiment, FIG. 5] As shown in FIG. 5, the ladder-type filter 70 is the same as the filter 1 shown in FIG.
1 in place of the piezoelectric component 5 (parallel resonator), FIG.
And a piezoelectric component 71 having the configuration described with reference to FIG. In FIG. 5, portions corresponding to FIGS. 2, 3, and 12 are denoted by corresponding reference numerals, and redundant description will be omitted.

Since the piezoelectric component 71 (parallel resonator) has a multilayer structure including the piezoelectric layers 41 to 43 and the electrode films 44 to 47, the capacitance of the parallel resonator 71 increases. Accordingly, the ratio between the capacitance of the parallel resonator 71 and the capacitance of the piezoelectric components 3 and 4 (series resonators) connected between the input terminal 1 and the output terminal 2 increases, and a good attenuation characteristic is obtained. The ladder type filter 70 having the ladder-type filter 70 can be obtained. In addition, the multilayer resonators 41 to 43 increase the mechanical strength of the parallel resonator 71.

[Third Embodiment, FIG. 6] As shown in FIG. 6, the ladder filter 70a is composed of the piezoelectric components 3 and 4 (series resonators) and the piezoelectric component 5 of the filter 11 described in FIG.
Instead of the (parallel resonator), piezoelectric components 73 and 74 (series resonators) and a piezoelectric component 75 (parallel resonator) having the configuration described with reference to FIGS. 2 and 3 are used. However,
Among these piezoelectric components 73 to 75, the parallel resonator 75 is formed by laminating more piezoelectric layers and electrode films than the series resonators 73 and 74, and the capacitance thereof is the capacitance of each of the series resonators 73 and 74. It is made to be larger than the capacity. FIG.
Also, the same reference numerals are given to portions corresponding to FIGS. 2, 3, and 12, and duplicate description will be omitted.

The ladder-type filter 70a includes a parallel resonator 75
Is larger than the number of series resonators 73 and 74, the capacitance of the parallel resonator 75 and the series resonators 73 and 74 are larger.
The ratio with respect to the capacitance becomes larger. Thus, a ladder-type filter 70a having good attenuation characteristics can be obtained. Further, the input-side piezoelectric component 73 and the output-side piezoelectric component 74 connected to the input terminal 1 and the output terminal 2, respectively, form a multilayer structure with the piezoelectric layers 41 to 43 and the electrode films 44 to 47. The capacitance of the piezoelectric components 73 and 74 increases, and the impedance of the piezoelectric components 73 and 74 decreases. Therefore, impedance matching when connecting an external circuit having low impedance to the ladder-type filter 70a is facilitated.

[Fourth Embodiment, FIG. 7] As shown in FIG. 7, the ladder filter 70b is the same as the ladder filter 70 described with reference to FIG. In this case, the piezoelectric components 3a and 4a that vibrate in the expansion vibration mode are used instead of the sub-elements. In addition,
7, parts corresponding to those in FIG. 5 are denoted by corresponding reference numerals, and redundant description will be omitted.

The ladder type filter 70a includes a piezoelectric component 71
The (parallel resonator) includes the piezoelectric layers 41 to 43 and the electrode films 44 to
47 and 47 constitute a multilayer structure.
Increases in capacitance. Accordingly, the ratio between the capacitance of the piezoelectric component 71 and the capacitance of the piezoelectric components 3a and 4a (series resonators) connected to the input terminal 1 or the output terminal 2 increases, and the filter having good attenuation characteristics. 70a can be obtained. Also, input terminal 1 or output terminal 2
Are connected to the piezoelectric components 3a and 4a (series resonators) because the opposing areas of the vibrating electrodes are large and the capacitance is large.
Low impedance. Therefore, the ladder filter 70
a can easily achieve impedance matching with an external circuit having a low input / output impedance.

[Fifth Embodiment, FIGS. 8 and 9] As shown in FIG. 8, the piezoelectric component 81 is the same as the piezoelectric component 40 having the configuration shown in FIG. A groove 82 running in the longitudinal direction is formed, and the electrode film 44 and the electrode film 46 are respectively formed by the groove 82 into two electrode films 44.
a, 44b and 46a, 46b,
This is a three-terminal type piezoelectric component. Piezoelectric component 8
One divided electrode film 46a and the electrode film 45 are electrically connected by a via hole 83, and the divided electrode film 44a and the electrode film 47 are electrically connected by a via hole 84. Similarly, the divided electrode film 46b and the electrode film 45 of the piezoelectric component 81 are electrically connected to each other by a via hole 85, and the divided electrode film 44b and the electrode film 4 are separated.
7 is electrically connected by a via hole 86.
The electrode films 46a and 46b are connected to an input terminal 91 and an output terminal 92, respectively, and the electrode film 47 is connected to a ground terminal 93.
It is connected to the.

In the three-terminal type piezoelectric component 81 having the above-described structure, since the three piezoelectric layers 41a (41b), 42, and 43 are laminated, the three-terminal type piezoelectric component 81 is connected between the input terminal 91 and the ground terminal 93. And the capacitance between the output terminal 92 and the ground terminal 93 increases. Therefore, the piezoelectric component 81 can easily achieve impedance matching with an external circuit having low input / output impedance.

[Other Embodiments] The present invention is not limited to the above embodiment, and can be variously modified within the scope of the gist.

For example, in the piezoelectric component shown in FIGS. 2 and 3, the connection between the electrode films 45 and 46 and the connection between the electrode films 44 and 47 are performed.
Connection is made at any position and number. Also, as shown in FIG. 10, connection electrodes 100, 10 formed on the side surfaces and end surfaces of the stacked body 40 are replaced with the via holes 48, 49.
1 may be performed. In this case, the connection electrode 10
Reference numerals 0 and 101 are electrically insulated from the electrode films 44 and 45 by insulating films 102 and 103 formed on the side and end surfaces of the stacked body 40, respectively. Further, the shapes, the number of layers, the thickness, and the like of the piezoelectric layers 41 to 43 and the electrode films 44 to 47 are also arbitrary.

[0035]

As is apparent from the above description, according to the present invention, a plurality of piezoelectric layers and a plurality of electrode films are stacked to form a laminate, and the polarization axes of the respective piezoelectric layers are aligned. At the same time, the polarization directions of the adjacent piezoelectric layers are opposite to each other, and the laminate vibrates in the length vibration mode in a direction orthogonal to the polarization direction of the piezoelectric layer. The capacitance of the component increases, and the impedance of the piezoelectric component can be reduced. In addition, a multilayered piezoelectric layer can provide a small-sized piezoelectric component having high mechanical strength.

Further, if the electrode films that need to be electrically connected are connected by via holes, the electrode films can be electrically connected inside the laminated body, and the electrode for connection can be provided outside the piezoelectric component. There is no need to draw out or form an insulating film for preventing a short circuit between the connection electrode and the electrode film, which simplifies the structure of the piezoelectric component and facilitates its manufacture.

In a piezoelectric device in which a series resonator and a parallel resonator are connected in a ladder shape between an input terminal and an output terminal, a plurality of resonators may be used as at least one of the series resonator and the parallel resonator. The piezoelectric layer and a plurality of electrode films are stacked to form a laminate, the polarization axes of the respective piezoelectric layers are aligned, and the polarization directions of the adjacent piezoelectric layers are opposite to each other. Since a piezoelectric component that vibrates in the length vibration mode in a direction orthogonal to the polarization direction of the piezoelectric layer is employed, when the piezoelectric component is employed for the series resonator, the number of stacked piezoelectric layers increases. Accordingly, the capacitance of the series resonator increases. Therefore, the impedance of the series resonator also becomes low, and impedance matching when connecting an external circuit having low impedance to the piezoelectric device becomes easy. On the other hand, when the piezoelectric component is used for the parallel resonator, the capacitance of the parallel resonator increases as the number of stacked piezoelectric layers increases. Therefore, the ratio of the capacitance of the parallel resonator to the capacitance of the series resonator increases, and when this piezoelectric device is used as a filter, the attenuation characteristics are improved. In addition, the mechanical strength of the piezoelectric component is increased, and a highly reliable piezoelectric device resistant to shock can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a filter according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a piezoelectric component used in the filter of FIG.

FIG. 3 is a cross-sectional view showing a polarization relationship of a piezoelectric layer and a connection relationship between electrode films constituting the piezoelectric component of FIG. 2;

FIG. 4 is an equivalent circuit diagram of the filter of FIG. 1;

FIG. 5 is a perspective view illustrating a configuration of a filter according to a second embodiment of the present invention.

FIG. 6 is a perspective view illustrating a configuration of a filter according to a third embodiment of the present invention.

FIG. 7 is a perspective view illustrating a configuration of a filter according to a fourth embodiment of the present invention.

FIG. 8 is a perspective view of a three-terminal type piezoelectric component showing a fifth embodiment of the present invention.

FIG. 9 is a transverse sectional view of the three-terminal type piezoelectric component of FIG. 8;

FIG. 10 is a perspective view of a piezoelectric component showing another embodiment.

FIG. 11 is a circuit diagram of a ladder filter.

FIG. 12 is a perspective view showing a configuration of a conventional filter having the circuit configuration of FIG. 11;

FIG. 13 is a perspective view showing a configuration of a conventional filter having the circuit configuration of FIG. 11;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input terminal 2 ... Output terminal 3, 4, 3a, 4a ... Piezoelectric component 13, 14 ... Piezoelectric layer 13a, 13b, 14a, 14b ... Vibration electrode 30 ... Ladder type filter 31-35 ... Piezoelectric component 40 ... Laminated body 41 to 43: Piezoelectric layers 44 to 47: Electrode films 44a, 44b, 46a, 46b: Electrode films 48, 49: Via holes 52, 54, 55: Piezoelectric layers 52a, 52b, 54a, 54b, 55a, 55b: Vibration Electrode 61: input terminal 62: output terminal 70, 70a, 70b: piezoelectric device 71, 73 to 75: piezoelectric component 81: piezoelectric component 82: concave groove 83 to 86: via hole

Claims (4)

[Claims] 1. A laminated body comprising a plurality of piezoelectric layers and a plurality of electrode films stacked on each other, the polarization axes of the respective piezoelectric layers are aligned, and the polarization directions of adjacent piezoelectric layers are opposite to each other. Wherein the laminate vibrates in a length vibration mode in a direction orthogonal to a polarization direction of the piezoelectric layer. 2. The piezoelectric component according to claim 1, wherein the plurality of electrode films are electrically connected via a via hole. 3. A piezoelectric device comprising the piezoelectric component according to claim 1. 4. A series resonator and a parallel resonator are connected in a ladder shape between an input terminal and an output terminal, and at least one of the series resonator and the parallel resonator is at least one of the resonators. A piezoelectric device, which is the piezoelectric component described above.