JPH10215140A - Piezoelectric resonator and electronic component using the resonator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric resonator of large mechanical strength and small spuriousness. SOLUTION: This piezoelectric resonator 10 is provided with a base body 12 in a rectangular parallelepiped shape, the base body 12 is provided with laminated five piezoelectric body layers 12a and the five piezoelectric body layers 12a are polarized in one direction along the longitudinal direction of the base body 12. Electrodes 14 are respectively formed among the piezoelectric body layers 12a of the base body 12 and at both end faces, every other electrodes 14 are connected to an external electrode 20 and the other electrodes 14 are connected to the other external electrode 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric resonator and an electronic component using the same, and more particularly to, for example, 1 MHz.
A piezoelectric resonator used in a high frequency band of about 20 MHz and utilizing mechanical resonance of a piezoelectric body, and an oscillator using the same;
The present invention relates to electronic components such as discriminators and filters.

[0002]

2. Description of the Related Art Conventionally, as a piezoelectric resonator used in a high frequency band of, for example, 1 MHz to 20 MHz, there are a piezoelectric resonator utilizing thickness shear vibration and a piezoelectric resonator utilizing thickness longitudinal vibration.

FIG. 21 is a perspective view showing an example of a conventional piezoelectric resonator utilizing thickness shear vibration. The piezoelectric resonator 1 shown in FIG. 21 includes a rectangular plate-shaped piezoelectric substrate 2. The piezoelectric substrate 2 is polarized in a direction indicated by an arrow in FIG. 21 perpendicular to the thickness direction. The electrodes 3 are provided on both sides of the piezoelectric substrate 2.
Are respectively formed. By inputting a signal between these electrodes 3, an electric field is applied in the thickness direction of the piezoelectric substrate 2, and the piezoelectric substrate 2 undergoes shear vibration.

FIG. 22 is a perspective view showing an example of a conventional piezoelectric resonator utilizing thickness longitudinal vibration. The piezoelectric resonator 1 shown in FIG. 22 includes a rectangular plate-shaped piezoelectric substrate 2 polarized in the thickness direction indicated by an arrow in FIG. 22, and electrodes 3 are formed on both surfaces of the piezoelectric substrate 2. By inputting a signal between the electrodes 3, an electric field is applied in the thickness direction of the piezoelectric substrate 2, and the piezoelectric substrate 2 vibrates in the thickness direction. Thus, the piezoelectric resonator 1 utilizing the thickness longitudinal vibration has been put to practical use as a resonator utilizing a fundamental wave and a third harmonic.

[0005]

In each of the piezoelectric resonators 1 shown in FIGS. 21 and 22, the resonance frequency is inversely proportional to the thickness of the piezoelectric substrate 2. Therefore, in order to use them as resonators in a high frequency band, The thickness of the piezoelectric substrate 2 must be reduced. However, there is a limit to the processing accuracy of the piezoelectric substrate 2 and the strength of the ceramic itself, which is a material of the piezoelectric substrate 2, and it is difficult to form the piezoelectric substrate 2 thinner than a certain thickness. Therefore, these piezoelectric resonators 1 have a problem in mechanical strength when the frequency is increased.

Further, in the piezoelectric resonator 1 utilizing the thickness shear vibration shown in FIG. 21, when the fundamental vibration is excited,
Odd harmonics of the fifth and seventh orders are generated as spurious.

Further, the piezoelectric resonator 1 utilizing the thickness longitudinal vibration shown in FIG. 22 has been put into practical use as a resonator in a high frequency band utilizing the third harmonic, but this originally excites the fundamental vibration. In this case, harmonics generated as spurious components are used in reverse. In this case, odd harmonics such as a fundamental wave and fifth and seventh harmonics are generated as spurious components. Such a fundamental wave and a harmonic wave cause abnormal oscillation when the piezoelectric resonator is used as an oscillator, for example.

[0008] Therefore, a main object of the present invention is to provide a piezoelectric resonator having less mechanical strength and small spurious.

Another object of the present invention is to provide an electronic component using a piezoelectric resonator having a small mechanical strength and a small spurious.

[0010]

The invention according to claim 1 includes a base having a longitudinal direction, and a plurality of electrodes orthogonal to the longitudinal direction of the base and arranged at intervals in the longitudinal direction of the base. Wherein the substrate includes a plurality of piezoelectric layers to be stacked,
A plurality of electrodes are formed between a plurality of piezoelectric layers, the plurality of piezoelectric layers are polarized in one direction along the longitudinal direction of the base, and the plurality of piezoelectric layers are formed on both sides of the electrodes along the longitudinal direction of the base. A piezoelectric resonator including a configuration in which electric fields are applied in mutually opposite directions, wherein when a distance between electrodes is d, a width of a base is w, and a thickness of the base is t, w / d ≦ 2 and t / d ≦
0.8, which is a piezoelectric resonator.

The invention according to claim 2 includes a base having a longitudinal direction, and a plurality of electrodes orthogonal to the longitudinal direction of the base and arranged at intervals in the longitudinal direction of the base. A plurality of piezoelectric layers are included, a plurality of electrodes are formed between the plurality of piezoelectric layers, the plurality of piezoelectric layers are polarized in one direction along the longitudinal direction of the base, and the plurality of piezoelectric layers are on both sides of the electrodes. A piezoelectric resonator including a configuration in which electric fields are applied in opposite directions along the longitudinal direction of the substrate, where the distance between the electrodes is d, the width of the substrate is w, and the thickness of the substrate is t. In addition, the piezoelectric resonator has t / d ≦ 2 and w / d ≦ 0.8.

The invention according to claim 3 includes a base having a longitudinal direction, and a plurality of electrodes orthogonal to the longitudinal direction of the base and arranged at intervals in the longitudinal direction of the base. A plurality of piezoelectric layers are included, a plurality of electrodes are formed between the plurality of piezoelectric layers, and the plurality of piezoelectric layers are polarized in opposite directions along the longitudinal direction of the base on both sides of the electrodes, and a plurality of piezoelectric layers are formed. Is a piezoelectric resonator including a configuration in which an electric field is applied in one direction along the longitudinal direction of the base, where the distance between the electrodes is d, the width of the base is w, and the thickness of the base is t. In addition, the piezoelectric resonator satisfies w / d ≦ 2 and t / d ≦ 0.8.

According to a fourth aspect of the present invention, there is provided a substrate having a longitudinal direction, and a plurality of electrodes arranged at right angles to the longitudinal direction of the substrate and spaced from each other in the longitudinal direction of the substrate. A plurality of piezoelectric layers are included, a plurality of electrodes are formed between the plurality of piezoelectric layers, and the plurality of piezoelectric layers are polarized in opposite directions along the longitudinal direction of the base on both sides of the electrodes, and a plurality of piezoelectric layers are formed. Is a piezoelectric resonator including a configuration in which an electric field is applied in one direction along the longitudinal direction of the base, where the distance between the electrodes is d, the width of the base is w, and the thickness of the base is t. In addition, the piezoelectric resonator has t / d ≦ 2 and w / d ≦ 0.8.

According to a fifth aspect of the present invention, in the above-described piezoelectric resonator, L is sufficiently larger than w, t, and d, respectively, where L is a length in the longitudinal direction of the base. .

According to a sixth aspect of the present invention, there is provided an electronic component using the above-described piezoelectric resonator.

According to a seventh aspect of the present invention, there is provided a ladder-type filter including the above-described piezoelectric resonator.

[0017]

In the piezoelectric resonator according to the first or second aspect of the present invention, the plurality of piezoelectric layers are polarized in one direction along the longitudinal direction of the base. , Electric fields are applied in opposite directions along the longitudinal direction of the substrate. Therefore, adjacent piezoelectric layers make fundamental vibrations having phases opposite to each other. Therefore, a compression wave, which is a harmonic having the same order as the number of piezoelectric layers, is excited in the base. When the compression wave is excited in the base in this way, spurious components other than the compression wave are reduced.

In the piezoelectric resonator according to the third or fourth aspect of the present invention, the plurality of piezoelectric layers are polarized in opposite directions along the longitudinal direction of the base on both sides of the electrode. An electric field is applied to the body layer in one direction along the longitudinal direction of the base. Therefore, adjacent piezoelectric layers make fundamental vibrations having phases opposite to each other. Therefore, a compression wave, which is a harmonic having the same order as the number of piezoelectric layers, is excited in the base. When the compression wave is excited in the base in this way, spurious components other than the compression wave are reduced.

Further, in the piezoelectric resonator according to any one of the first to fourth aspects of the present invention, the wavelength of the compression wave excited by the base depends on the distance between the electrodes. Therefore,
Even if the interval between the electrodes is narrowed to increase the frequency of the compressional wave, only the length in the longitudinal direction of the base is reduced, and the thickness and width of the base are not reduced, so that the mechanical strength is maintained. Is done.

Further, in the piezoelectric resonator according to any one of the first to fourth aspects of the present invention, when the interval between the electrodes is d, the width of the base is w, and the thickness of the base is t,
Since w / d ≦ 2 and t / d ≦ 0.8, or t / d ≦ 2 and w / d ≦ 0.8, unnecessary vibration in the width direction and the thickness direction of the base is suppressed.

[0021]

According to the present invention, it is possible to obtain a piezoelectric resonator having less mechanical strength and small spurious.

Further, in the piezoelectric resonator according to the present invention,
Unnecessary vibration in the width direction and the thickness direction of the base is suppressed.

Further, according to the present invention, there can be obtained an electronic component using a piezoelectric resonator having little mechanical strength and small spurious.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention with reference to the accompanying drawings.

[0025]

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is an illustrative view of the embodiment. FIG.
The piezoelectric resonator 10 shown in FIG. 2 includes, for example, a rectangular parallelepiped base 12. The base 12 includes, for example, five stacked piezoelectric layers 12a made of piezoelectric ceramics. These piezoelectric layers 12a are formed in the same size. These piezoelectric layers 12a are polarized in one direction along the longitudinal direction of the base 12, as indicated by the arrows in FIG.

Six electrodes 14 are formed between the five piezoelectric layers 12a of the base 12 and on both end faces. Therefore, these electrodes 14 are arranged at right angles to the longitudinal direction of the base 12 and at intervals in the longitudinal direction of the base 12.

A plurality of insulating films 16 and 18 are formed on the upper and lower surfaces of the base 12, respectively. On the upper surface of the base 12, every other exposed portion of the end face of the electrode 14 is covered with the insulating film 16. On the lower surface of the base 12, an exposed portion of the end face of the electrode 14 that is not covered with the insulating film 16 on the upper surface of the base 12 is covered with the insulating film 18. Base 1 on which these insulating films 16 and 18 are formed
The upper surface and the lower surface of 2 respectively serve as connection portions with external electrodes described later.

External electrodes 20 and 22 are formed on these connection portions, that is, on the upper and lower surfaces of the base 12 on which the insulating films 16 and 18 are formed, respectively. Therefore, the electrode 14 not covered with the insulating film 16 is connected to the external electrode 20, and the electrode 14 not covered with the insulating film 18 is connected to the external electrode 22. That is, the plurality of electrodes 14 are alternately connected to the external electrodes 20 and 22 in order from the one on the one end side to the other end side in the longitudinal direction of the base 12.

Next, an example of a method for manufacturing the piezoelectric resonator 10 will be described.

First, as shown in FIG. 3, a plurality of piezoelectric ceramic green sheets 30 are prepared. A conductive paste containing, for example, silver, palladium, or an organic binder is applied to one main surface of the green sheet 30 to form a conductive paste layer 32. The conductive paste layer 32 is formed on the entire surface except for one end of the green sheet 30.
Then, a laminate is formed by laminating the plurality of green sheets 30. At this time, the plurality of green sheets 30 are arranged such that the edge portions where the conductive paste layer 32 is not formed are not overlapped by adjacent layers.
It is laminated. Also, on the top green sheet 30,
The conductive paste layer 32 is not formed. Then, the laminated block is formed by firing the laminated body.

As shown in FIG. 4, the laminated block 34
It includes a plurality of stacked piezoelectric layers 36, and electrodes 38 are formed between the piezoelectric layers 36, respectively. These electrodes 38 are alternately exposed from opposing side surfaces of the laminated block 34. The electrodes 4 are formed on the upper and lower surfaces of the laminated block 34 by, for example, sputtering.
0 and 42 are formed. And these electrodes 40
When a high DC voltage is applied between the piezoelectric layers 36 and 42, the plurality of piezoelectric layers 36 of the laminated block 34 are polarized in the same direction as the lamination direction, as indicated by arrows in FIG.

Next, as shown by a dotted line in FIG. 5, the laminated block 34 is cut by a dicer or the like so as to be orthogonal to the plurality of electrodes 38. Thereby, the plate-like body 4 shown in FIG.
4 are formed.

Then, on one main surface of the plate-like body 44,
A resin insulating material (not shown) is applied so as to cover the end face of every other electrode 38. Further, a resin insulating material (not shown) is applied on the other main surface of the plate-shaped body 44 so as to cover the end faces of the other electrodes 38. Further, on both main surfaces of the plate-like body 44, external electrodes made of silver are formed by, for example, a method such as sputtering so as to cover a resin insulating material or the like. And the plate-like body 44
6 is cut by a dicer or the like so as to be orthogonal to the plurality of electrodes 38 as shown by a dotted line in FIG. Thereby, a piezoelectric resonator is made.

The piezoelectric resonator 1 shown in FIGS.
0 has five piezoelectric layers 12a, but FIGS. 4, 5 and 6 show a method of manufacturing a piezoelectric resonator having six piezoelectric layers 36 for convenience.

In the piezoelectric resonator 10, the five piezoelectric layers 12a are polarized in one direction along the longitudinal direction of the base 12, but when a signal is inputted between the external electrodes 20 and 22, the five piezoelectric layers 12a are polarized. Electric fields are applied to the piezoelectric layer 12 a in opposite directions along the longitudinal direction of the base 12 on both sides of the electrode 14. Therefore, as shown in FIG. 7, the adjacent piezoelectric layers 12a oscillate fundamentally in opposite phases. Therefore,
The compression wave which is the fifth harmonic of the same order as the number of the piezoelectric layers 12a is excited in the base 12. When the compression wave is excited in the base 12 in this manner, spurious components other than the compression wave are reduced.

In the piezoelectric resonator 1 utilizing the normal length longitudinal vibration shown in FIG. 23, when a signal is input between the electrodes 3 formed on both main surfaces of the piezoelectric substrate 2, as shown in FIG. Next, the entire piezoelectric substrate 2 fundamentally vibrates. As shown in FIG. 25, the impedance frequency characteristic of the piezoelectric substrate 2 is accompanied by the fundamental vibration, and an odd harmonic of the frequency of the fundamental vibration is generated as spurious.

In this piezoelectric resonator 10, as shown in FIG. 8, the distance between the electrodes 14 is d, and the width of the base 12 is w.
And when the thickness of the base 12 is t, d = 0.2 m
FIG. 9 shows impedance frequency characteristics when m, w = 0.4 mm, and t = 0.16 mm. As is clear from the impedance frequency characteristics shown in FIG. 9, it is understood that spurious components other than the main peak of about 10 MHz are small in the piezoelectric resonator 10.

Further, in the piezoelectric resonator 10, the base 1
The wavelength of the compression wave excited in 2 depends on the distance d between the electrodes 14. Therefore, even if the distance d between the electrodes 14 is reduced in order to reduce the wavelength of the compressional wave, that is, to increase the frequency, only the length of the base 12 in the longitudinal direction is reduced. Since the thickness t and the width w do not decrease, the mechanical strength is maintained.

In this piezoelectric resonator 10, d =
For the case of 0.2 mm or d = 0.4 mm, calculation was performed by the finite element method. In this case, a potential of 0 V is applied to every other electrode 14 and the other electrodes 14
Was applied, and the width w and thickness t of the base 12 were changed, and the resonance frequency Fr, the antiresonance frequency Fa, and the difference ΔF between the resonance frequency Fr and the antiresonance frequency Fa were examined. These results are shown in FIG. 10 and FIG.

As is clear from the results shown in FIG. 10, when the thickness t of the base 12 is reduced, that is, when t / d is reduced, ΔF / Fa increases. And ΔF / Fa
Is that when t is 0.16 mm, that is, t / d is 0.8
At the time, it is almost maximum. However, when the width w of the base 12 is 0.5 mm or 0.45 mm, that is, when w / d is 2.5 or 2.25, Δt in the range of t / d ≦ 0.8
F / Fa decreases. Therefore, the width w of the base 12 is set to 0.4.
mm / 0.3 mm, that is, by setting w / d to 2.0 or 1.5, t / d ≦
It can be seen that in the range of 0.8, ΔF / Fa becomes almost constant without decreasing.

Similarly, from the results shown in FIG. 11, w / d
≦ 2 and t / d ≦ 0.8, ΔF /
It can be seen that Fa takes a large value.

Note that the width w and the thickness t of the base 12 are the same even if they are interchanged, so that t / d ≦ 2 and w /
It can be seen that even when the condition of d ≦ 0.8 is satisfied, ΔF / Fa takes a large value.

Therefore, in this piezoelectric resonator 10, w
When / d ≦ 2 and t / d ≦ 0.8, or when t / d ≦ 2 and w / d ≦ 0.8, ΔF / Fa takes a large value.

In this piezoelectric resonator 10, d =
FIG. 12 shows impedance frequency characteristics when 0.2 mm, w = 0.3 mm, and t = 0.3 mm, and d =
FIG. 13 shows impedance frequency characteristics when 0.2 mm, w = 0.3 mm, and t = 0.15 mm.

As is apparent from the impedance frequency characteristics shown in FIGS. 12 and 13, in the piezoelectric resonator 10, the distance d between the electrodes 14, the width w of the base 12, and the thickness t of the base 12 are defined as w / d ≦ 2 and t / d ≦ 0.8, or
It can be seen that by setting t / d ≦ 2 and w / d ≦ 0.8, the main peak at about 10 MHz greatly increases and the spurious at about 6 MHz decreases.

Therefore, in this piezoelectric resonator 10, when the distance between the electrodes 14 is d, the width of the base 12 is w, and the thickness of the base 12 is t, w / d ≦ 2 and t / d ≦
When the ratio is 0.8 or t / d ≦ 2 and w / d ≦ 0.8, unnecessary vibration in the width direction and the thickness direction of the base 12 is suppressed.

Further, in the piezoelectric resonator 10, since the capacitance generated between the adjacent electrodes 14 is connected in parallel between the external electrodes 20 and 22, a large capacitance can be obtained. Further, the capacitance of the piezoelectric layer 12a
, The distance d between the electrodes 14, the width w of the base 12, or the thickness t of the base 12, can be easily changed.

FIG. 14 is an illustrative view showing another example of the embodiment of the present invention. The piezoelectric resonator 10 shown in FIG. 14 is different from the piezoelectric resonator 10 shown in FIGS. 1 and 2 in that the insulating films 16 and 18 are not formed, and the external electrodes 20 and 22 are connected to the electrodes 14 on both sides. They are formed at both ends of the lower surface of the base 12 so as to be connected to each other.

In order to manufacture the piezoelectric resonator 10 shown in FIG. 14, first, the laminated block 3 is manufactured in the same manner as described above.
4 are formed. As shown in FIG. 15, the lamination block 34 includes a plurality of laminated piezoelectric layers 36, and electrodes 38 are formed between the piezoelectric layers 36, respectively. These electrodes 38 are alternately applied to the laminated blocks 34.
Is exposed from the opposite side surface. The laminated block 34 also has electrodes 38 on the upper and lower surfaces.
Are formed respectively. Then, on the opposing side surface of the laminated block, for example, by a method such as sputtering,
Electrodes 40 and 42 are formed, respectively. then,
By applying a high DC voltage between these electrodes 40 and 42, a plurality of piezoelectric layers 36
As shown by arrows in FIG. 15, adjacent layers are polarized in directions opposite to each other.

Next, as shown by a dotted line in FIG. 15, the laminated block 34 is cut by a dicer or the like so as to be orthogonal to the plurality of electrodes 38. Thereby, a plate-like body (not shown) is formed. External electrodes (not shown) made of silver are formed on the upper and lower ends of the plate-like body by, for example, a method such as sputtering. Then, the plate-like body is cut with a dicer or the like to produce a piezoelectric resonator.

In the piezoelectric resonator 10 shown in FIG. 14, the five piezoelectric layers 12a are polarized in opposite directions along the longitudinal direction of the base 12 on both sides of the electrode 14, but between the external electrodes 20 and 22. By inputting a signal, an electric field is applied to the five piezoelectric layers 12 a in one direction along the longitudinal direction of the base 12. Therefore, the adjacent piezoelectric layer 12a
Similar to the case shown in FIG. 7, fundamental vibrations having phases opposite to each other are performed. Therefore, the compression wave which is the fifth harmonic of the same order as the number of the piezoelectric layers 12a is excited in the base 12. When the compression wave is excited in the base 12 in this way,
Spurious components other than the next harmonic are reduced.

In the piezoelectric resonator 10 shown in FIG. 14, when the number of stacked piezoelectric layers 12a is 10, the distance between the electrodes 14 is d, the width of the base 12 is w, and the thickness of the base 12 is t. Where d = 0.2 mm, w = 1.0 mm, t =
FIG. 16 shows the impedance frequency characteristic when the distance is 0.18 mm. As is apparent from the impedance frequency characteristics shown in FIG.
A large main peak can be confirmed at MHz. Moreover, it can be seen that the piezoelectric resonator 10 has less spurious than the conventional piezoelectric resonator.

Further, in the piezoelectric resonator 10 shown in FIG. 14, the wavelength of the compression wave excited in the base 12 depends on the distance d between the electrodes 14. Therefore, in order to reduce the wavelength of the compressional wave, that is, to increase the frequency, the electrode 1
Even if the interval d between the bases 4 is reduced, only the length of the base 12 in the longitudinal direction is reduced, and the thickness t and the width w of the base 12 are not reduced, so that the mechanical strength is maintained.

In the piezoelectric resonator 10 shown in FIG.
As in the piezoelectric resonator 10 shown in FIGS. 1 and 2, w / d
≦ 2 and t / d ≦ 0.8, or t / d ≦ 2 and w /
When d ≦ 0.8, unnecessary vibration in the width direction and the thickness direction of the base 12 is suppressed.

Further, in the piezoelectric resonator 10 shown in FIG. 14, since the capacitance generated between the adjacent electrodes 14 is connected in series between the external electrodes 20 and 22, a small capacitance can be obtained. . The capacitance can be easily changed by changing the number of the piezoelectric layers 12a, the distance d between the electrodes 14, the width w of the base 12, or the thickness t of the base 12.

Each of the above-described piezoelectric resonators 10 is used for an electronic component such as an oscillator, a discriminator, and a filter.

When such an electronic component is used as an oscillator, since the above-described piezoelectric resonator 10 is used,
Spurious can be suppressed small, and abnormal oscillation due to spurious can be prevented. Further, since the capacitance value of the piezoelectric resonator 10 can be set freely, it is easy to achieve impedance matching with an external circuit. In particular, when used as an oscillator for a voltage controlled oscillator, the ΔF of the resonator is large, so that a wider frequency variable range than ever before can be obtained.

When such an electronic component is used as a discriminator, the feature that the resonator has a large ΔF leads to the feature that the peak separation is wide. Further, since the capacitance design range of the resonator is wide, it is easy to achieve impedance matching with an external circuit.

FIG. 17 is a plan view showing an example of a ladder-type filter using the piezoelectric resonator according to the present invention. The ladder filter 50 includes an insulator substrate 52. On the insulator substrate 52, four pattern electrodes 54, 56, 5
8 and 60 are formed.

The pattern electrode 54 has a portion 54 extending from one end to the other end in the longitudinal direction of the insulating substrate 52.
a and three portions 54b, 54c and 54d extending from the portion 54a toward one side of the insulator substrate 52. Further, other pattern electrodes 56, 58 and 6
Numerals 0 are formed in an I-shape, a substantially Y-shape, and a substantially S-shape from one side of the insulator substrate 52 toward the pattern electrode 54, respectively.

A piezoelectric resonator 10s1 shown in FIG. 18 is connected to the portion 54b of the pattern electrode 54 and the pattern electrode 56 as a series resonator connected in series.

The piezoelectric resonator 10s1 shown in FIG.
Compared with the piezoelectric resonator 10 shown in FIG. 4, in particular, eight piezoelectric layers 12a and nine electrodes 14 are alternately stacked.

The piezoelectric resonator 10s1 is connected to the external electrode 2 so that a gap is formed between the piezoelectric resonator 10s1 and the insulator substrate 52.
Nos. 0 and 22 are bonded to the portion 54b of the pattern electrode 54 and the pattern electrode 56, respectively, with a conductive adhesive.

Similarly, the external electrodes 20 and 22 of another piezoelectric resonator 10s2 as a series resonator are also connected to the portion 54d of the pattern electrode 54 and the pattern electrode 60 by a conductive adhesive.

A piezoelectric resonator 10p1 shown in FIG. 19 is connected to the portion 54c of the pattern electrode 54 and the pattern electrode 58 as a parallel resonator connected in parallel.

The piezoelectric resonator 10p1 shown in FIG.
7 of the piezoelectric layers 12a as compared with the piezoelectric resonator 10 shown in FIG.
And eight layers of electrodes 14 are alternately stacked. Also,
The insulating film 16 is formed on one side of the upper surface of the base 12 in the width direction so as to cover the end face of every other electrode 14. Further, the insulating film 18 is formed on the other side in the width direction of the upper surface of the base 12 so as to cover the end face of every other electrode 14. Further, the external electrodes 20 and 22 are formed on one side and the other side in the width direction of the upper surface of the base 12, and are connected to every other electrode 14 and every other electrode 14, respectively. Support members 24 and 26 made of a conductor are formed at the center of the external electrodes 20 and 22 in the longitudinal direction, respectively.

Then, the piezoelectric resonator 10p1 is supported by the support member 2 so that a gap is formed between the piezoelectric resonator 10p1 and the insulator substrate 52.
4 and 26 are respectively connected to the portion 54c of the pattern electrode 54 and the pattern electrode 58 with a conductive adhesive.

Similarly, the pattern electrode 58 and the pattern electrode 60 are connected to the other piezoelectric resonators 10 as parallel resonators.
The support members 24 and 26 of p2 are respectively connected by a conductive adhesive.

Therefore, the ladder type filter 50
Has an equivalent circuit shown in FIG.

In the ladder-type filter 50, a metal cap (not shown) is placed on the insulator substrate 52 so as to cover each of the piezoelectric resonators 10s1, 10s2, 10p1, and 10p2.

In the ladder-type filter 50, the number of stacked piezoelectric layers 12a of the piezoelectric resonators 10s1, 10s2, 10p1, and 10p2, the distance d between the electrodes 14, the width w of the base 12, or the thickness t of the base 12 are determined. By changing, the piezoelectric resonators 10s1, 10s2, 10p1, 10p
2 can be easily adjusted. Therefore,
In the ladder type filter 50, the piezoelectric resonators 10s1,
By adjusting the capacitances of 10s2, 10p1, and 10p2, a large amount of attenuation can be easily realized.
Further, the piezoelectric resonators 10s1, 10s2, 10p1, 10
Since ΔF of p2 is larger than that of the conventional piezoelectric resonator, it is possible to realize a wider passband than that using the conventional piezoelectric resonator.

The piezoelectric resonator 1 shown in FIGS.
At 0, if the ends of the plurality of electrodes 14 are formed alternately so as not to be exposed from the upper and lower surfaces of the base 12, the insulating films 16 and 18 become unnecessary.

Further, the piezoelectric resonators 10p1 and 10p1 shown in FIG.
Also in the case of 10p2, the insulating films 16 and 18 become unnecessary if the portion of the electrode 14 covered with the insulating films 16 and 18 is formed so as not to be exposed from the upper surface of the base 12.

Further, in each of the above-described piezoelectric resonators, all the piezoelectric layers are polarized, but in the present invention, some of the piezoelectric layers may be formed of unpolarized layers.

In each of the above-described piezoelectric resonators, one piezoelectric layer is provided between two adjacent electrodes, but a plurality of piezoelectric layers may be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an embodiment of the present invention.

FIG. 2 is an illustrative view of the piezoelectric resonator shown in FIG. 1;

FIG. 3 is a perspective view showing a state in which ceramic green sheets are stacked for manufacturing the piezoelectric resonator shown in FIGS. 1 and 2;

FIG. 4 is an illustrative view showing a step of polarizing a laminated block made from the ceramic green sheets shown in FIG. 3;

FIG. 5 is an illustrative view showing a cut portion of the laminated block shown in FIG. 4;

FIG. 6 is an illustrative view showing a plate-like body obtained by cutting the laminated block shown in FIG. 5;

FIG. 7 is an illustrative view showing a waveform of a fundamental vibration generated in the piezoelectric resonator shown in FIGS. 1 and 2;

8 is an illustrative view showing a relationship between a distance d between electrodes of the piezoelectric resonator shown in FIGS. 1 and 2 and a width w and a thickness t of a base;

FIG. 9 is a graph of the piezoelectric resonator shown in FIG. 1 and FIG.
9 is a graph showing frequency-impedance characteristics when 0.2 mm, w = 0.4 mm, and t = 0.16 mm.

FIG. 10 is a graph showing d in the piezoelectric resonator shown in FIGS. 1 and 2;
= 0.2 mm and t / d and Δ by the finite element method
It is a graph which shows the relationship with F / Fa.

FIG. 11 is a graph showing d in the piezoelectric resonator shown in FIGS. 1 and 2;
= 0.4 mm and t / d and Δ by the finite element method
It is a graph which shows the relationship with F / Fa.

FIG. 12 is a graph showing d in the piezoelectric resonator shown in FIGS. 1 and 2;
7 is a graph showing frequency-impedance characteristics when = 0.2 mm, w = 0.3 mm, and t = 0.3 mm.

FIG. 13 shows d in the piezoelectric resonator shown in FIGS. 1 and 2;
7 is a graph showing frequency-impedance characteristics when = 0.2 mm, w = 0.3 mm, and t = 0.15 mm.

FIG. 14 is an illustrative view showing another example of the embodiment of the present invention;

FIG. 15 is an illustrative view showing a step of polarizing a laminated block in order to manufacture the piezoelectric resonator shown in FIG. 14;

FIG. 16 is a diagram showing an example of the piezoelectric resonator shown in FIG.
6 is a graph showing frequency-impedance characteristics when 0 mm and t = 0.18 mm.

FIG. 17 is an illustrative plan view showing one example of a ladder-type filter using the piezoelectric resonator according to the present invention.

FIG. 18 is an illustrative view showing a piezoelectric resonator as a series resonator used in the ladder-type filter shown in FIG. 17;

FIG. 19 is an illustrative view showing a piezoelectric resonator as a parallel resonator used in the ladder-type filter shown in FIG. 17;

20 is an equivalent circuit diagram of the ladder-type filter shown in FIG.

FIG. 21 is a perspective view showing an example of a conventional piezoelectric resonator using thickness shear vibration.

FIG. 22 is a perspective view showing an example of a conventional piezoelectric resonator using thickness longitudinal vibration.

FIG. 23 is a perspective view showing an example of a conventional piezoelectric resonator using length vibration.

FIG. 24 is an illustrative view showing a waveform of a fundamental vibration generated in the piezoelectric resonator shown in FIG. 23;

25 is a graph showing frequency-impedance characteristics of the piezoelectric resonator shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Piezoelectric resonator 12 Base 12a Piezoelectric layer 14 Electrode 16, 18 Insulating film 20, 22 External electrode 24, 26 Supporting member

Claims (7)

[Claims] 1. A piezoelectric device comprising: a base having a longitudinal direction; and a plurality of electrodes orthogonal to the longitudinal direction of the base and arranged at intervals in the longitudinal direction of the base. A plurality of electrodes, the plurality of electrodes are formed between the plurality of piezoelectric layers, the plurality of piezoelectric layers are polarized in one direction along a longitudinal direction of the base, and the plurality of piezoelectric layers have the electrodes. A piezoelectric resonator including a configuration in which electric fields are applied in opposite directions along the longitudinal direction of the base on both sides of the base, wherein the distance between the electrodes is d, the width of the base is w, When the thickness is t, w / d ≦ 2 and t / d
A piezoelectric resonator with ≦ 0.8. 2. A piezoelectric device comprising: a base having a longitudinal direction; and a plurality of electrodes orthogonal to the longitudinal direction of the base and arranged at intervals in the longitudinal direction of the base. A plurality of electrodes, the plurality of electrodes are formed between the plurality of piezoelectric layers, the plurality of piezoelectric layers are polarized in one direction along a longitudinal direction of the base, and the plurality of piezoelectric layers have the electrodes. A piezoelectric resonator including a configuration in which electric fields are applied in opposite directions along the longitudinal direction of the base on both sides of the base, wherein the distance between the electrodes is d, the width of the base is w, When the thickness is t, t / d ≦ 2 and w / d
A piezoelectric resonator with ≦ 0.8. 3. A piezoelectric device comprising: a base having a longitudinal direction; and a plurality of electrodes orthogonal to the longitudinal direction of the base and arranged at intervals in the longitudinal direction of the base. Wherein the plurality of electrodes are formed between the plurality of piezoelectric layers, and the plurality of piezoelectric layers are polarized in opposite directions along a longitudinal direction of the base on both sides of the electrodes; The body layer is a piezoelectric resonator including a configuration in which an electric field is applied in one direction along the longitudinal direction of the base, wherein a distance between the electrodes is d, a width of the base is w, and a width of the base is When the thickness is t, w / d ≦ 2 and t / d
A piezoelectric resonator with ≦ 0.8. 4. A substrate having a longitudinal direction, and a plurality of electrodes orthogonal to the longitudinal direction of the substrate and arranged at intervals in the longitudinal direction of the substrate, wherein the substrate is composed of a plurality of laminated piezoelectric members. Wherein the plurality of electrodes are formed between the plurality of piezoelectric layers, and the plurality of piezoelectric layers are polarized in opposite directions along a longitudinal direction of the base on both sides of the electrodes; The body layer is a piezoelectric resonator including a configuration in which an electric field is applied in one direction along the longitudinal direction of the base, wherein a distance between the electrodes is d, a width of the base is w, and a width of the base is When the thickness is t, t / d ≦ 2 and w / d
A piezoelectric resonator with ≦ 0.8. 5. The piezoelectric resonator according to claim 1, wherein L is sufficiently larger than w, t, and d, respectively, where L is a length in the longitudinal direction of the base. 6. An electronic component using the piezoelectric resonator according to claim 1. Description: 7. A ladder-type filter comprising the piezoelectric resonator according to claim 1. Description: