JPH10135764A - Piezoelectric resonator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an piezoelectric resonator that utilizes the area vibration mode with excellent mechanical shock performance in which fluctuation in the resonance characteristic and the filter characteristic is hardly caused while simplifying the support structure. SOLUTION: In a ladder filter where a plurality of piezoelectric resonators 22-25 utilizing the width spread mode are laminated and integrated via an elastic resin material 39, the elastic resin material 39 has a tensile strength of 15-45kg/cm<2> and a ratio of the provision of the elastic resin material 39 to the piezoelectric resonators 22-25 is selected to be within a range of 5-48% of the area of the major side of the piezoelectric resonator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric resonator using an area vibration mode such as a square plate expansion mode and a rectangular plate width expansion mode, and more particularly, to a piezoelectric resonator supported by an elastic resin material. The present invention relates to a piezoelectric resonance device having a structure formed as described above.

[0002]

2. Description of the Related Art Hitherto, in order to constitute a piezoelectric oscillator and various filters, a piezoelectric resonator and a piezoelectric resonance component using various vibration modes according to the frequency have been proposed. For example, as a piezoelectric resonator used in a band of several hundred kHz, a piezoelectric resonator using a spreading vibration mode of a piezoelectric plate having a square planar shape is known.

In the spreading vibration mode, the node of vibration is located at the center of both principal surfaces. Therefore, when the piezoelectric resonator is mechanically supported using the peripheral portion of the piezoelectric plate, the resonance characteristics are impaired. Therefore, conventionally, in a piezoelectric resonator using the spread vibration mode, the piezoelectric resonator is supported by using a spring terminal that makes elastic contact with the center of the main surface of the piezoelectric plate.

A ladder-type filter as an example of a piezoelectric resonance device using a spreading mode will be described with reference to FIG. In the ladder-type filter shown in FIG. 1, four piezoelectric resonators 1 to 4 using a spreading mode are used. The piezoelectric resonators 1 and 2 form a series resonator in the circuit configuration of the ladder filter, and the piezoelectric resonators 3 and 4 form a parallel resonator. The piezoelectric resonators 1 to 4 have conductive elastic plates 5 to 5.
It is housed in the opening 12a of the case 12 in a state where it is arranged as shown in FIG.

[0005] Terminals 11 and the like are arranged outside the piezoelectric resonators 1 to 4. The elastic plates 5 to 7 and the terminals 8 to
The portion of each of the eleven piezoelectric resonators 1 to 4 that is in contact with the electrode is the center of the main surface of each of the piezoelectric resonators 1 to 4.

As described above, in a conventional piezoelectric resonance device using a plurality of piezoelectric resonators utilizing the spread mode, the node point of vibration is located at the center of the main surface of the piezoelectric resonator. It had to be mechanically supported and stored in a case or the like. Therefore, there are problems that the number of parts increases and the assembly process becomes complicated.

On the other hand, as a solution to the above problem, Japanese Patent Laid-Open No. 7-154195 discloses a ladder type filter using a piezoelectric resonator using a widening mode. The piezoelectric resonator using the width expansion mode is such that when the length of the short side is a and the length of the long side is b, and the Poisson ratio of the piezoelectric material is σ, the ratio b / a is:

[0008]

(Equation 1)

[0009] A rectangular plate-shaped piezoelectric vibrating body is used in a range of ± 10% around a value satisfying the condition. It has been confirmed by the present inventor that in a piezoelectric resonator using the width expansion mode, the vibration node portion is located at the center of the main surface of the rectangular piezoelectric plate and the center of the short side surface.
Therefore, the piezoelectric resonator using the width expansion mode can be supported at the center of the side surface on the short side, and can be supported without using a support structure using a complicated spring terminal or the like.

In Japanese Patent Application Laid-Open No. Hei 7-154195, a series resonator and a parallel resonator of a ladder-type filter are constituted by using a piezoelectric resonator utilizing the above-mentioned widening mode.
Therefore, a ladder-type filter that does not require a complicated support structure such as the above-described spring terminal is configured.

Japanese Unexamined Patent Publication No. 7-154195 discloses a ladder-type filter using a piezoelectric resonator utilizing the above-mentioned width expansion mode, in which a plurality of resonators constituting a series resonator and a parallel resonator are electrically conductive. Laminated using a conductive adhesive,
An integrated structure is disclosed.

[0012]

In the case of supporting a piezoelectric resonator utilizing a width expansion mode or a square plate expansion mode, a structure in which an adhesive is applied to a node or in the vicinity of the node may be used to make a complicated spring terminal or the like. There is no need to use

However, in a piezoelectric resonator using the area vibration mode, desired characteristics may not be obtained even if the piezoelectric resonator is supported using an elastic adhesive. That is, the resonance characteristics may deviate from the desired resonance characteristics due to the elastic adhesive used for the support structure, or the filter waveform may be distorted when applied to a filter device such as a ladder filter.

In addition, in general, the impact force G =
It is required to be able to withstand an impact force of about 3000G. However, in a piezoelectric resonator utilizing an area vibration mode in which a support structure is formed using an elastic adhesive, impact resistance may not be sufficient depending on the type and amount of the elastic adhesive.

Accordingly, an object of the present invention is to provide a piezoelectric resonance apparatus utilizing an area vibration mode having a support structure using an elastic resin material, which can not only simplify the support structure but also provide desired resonance characteristics and a desired filter. An object of the present invention is to provide a piezoelectric resonance device that can obtain characteristics and is excellent in impact resistance.

[0016]

According to a broad aspect of the present invention, there is provided a piezoelectric resonator having a piezoelectric resonator utilizing an area vibration mode supported by using an elastic resin material.
The elastic resin material has a tensile strength of 15 to 45 kgf / cm ² , and is applied to the main surface of the resonator in a range of 5 to 48% of the area of the main surface. Is provided.

In the present invention, the area vibration mode is a vibration mode mainly composed of in-plane vibration, and includes a square plate expansion mode and the above-described width expansion mode.

In the piezoelectric resonator according to the present invention, the piezoelectric resonator is supported by the elastic resin material having the specific tensile strength, and the area to which the elastic resin material is applied is mainly the same as that of the piezoelectric resonator. The feature is that the range is 5% or more and 48% or less of the surface, thereby achieving the above object.

The elastic resin material used in the present invention is not particularly limited as long as it is an elastic resin that satisfies the above tensile strength in the structure supporting the piezoelectric resonator. Examples thereof include polyurethane resins.

In the present invention, the tensile strength is 15 to 45 k.
The use of the elastic resin material of gf / cm ² is, as is clear from the examples described later, when the tensile strength is less than 15 kgf / cm ^{2, the} impact resistance of the structure supporting the piezoelectric resonator is poor. This is because if it exceeds 45 kgf / cm ² , even if the amount of the elastic resin material applied to the piezoelectric resonator is changed, the change in the characteristics of the piezoelectric resonator becomes too large.

When the elastic resin material is applied within the range of 5% to 48% of the area of the main surface of the piezoelectric resonator, if it is less than 5%, sufficient mechanical resistance can be obtained while preventing fluctuations in characteristics. This is because it is difficult to achieve impact properties, and if it exceeds 48%, it becomes difficult to prevent fluctuations in the characteristics of the piezoelectric resonator.

In the piezoelectric resonance device of the present invention, preferably,
The elastic resin material is provided at or near a vibration node of the piezoelectric resonator, thereby effectively preventing deterioration of the characteristics of the piezoelectric resonator due to the support structure.

A ladder-type filter according to the present invention has at least one parallel arm resonator and at least one series arm resonator, and includes a plurality of piezoelectric resonators forming the series arm resonator and the parallel arm resonator. The elements are laminated and integrated in the thickness direction via an elastic resin material. Here, the elastic resin material is 15 to 45 as in the case of the piezoelectric resonance device of the present invention.
It has a tensile strength of kgf / cm ² and the elastic resin material is bonded to the main surface of the piezoelectric resonator at a rate of 5 to 48% of the main surface of each piezoelectric resonator.

Therefore, also in the ladder-type filter according to the present invention, the elastic resin material having the above specific tensile strength is used, and the elastic resin material is applied to the main surface of the piezoelectric resonator at the above specific ratio. As in the case of the piezoelectric resonance device according to the present invention, it is possible to reduce fluctuations in the characteristics of each piezoelectric resonator and increase mechanical shock resistance.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a piezoelectric resonance device according to the present invention will be described below with reference to the drawings. First Embodiment The present embodiment is applied to a ladder-type filter constituted by using four piezoelectric resonators using a width expansion mode as an area vibration mode.

As shown in FIG. 2, the ladder-type filter according to the present embodiment has a piezoelectric resonator 22,
It has a structure in which a cap 26 made of metal is attached to a structure in which 23, 24, and 25 are stacked. FIG. 6 shows an appearance of the ladder-type filter, and FIG. 3 shows a cross section thereof.

The details of the structure in which the piezoelectric resonators 22 to 25 are laminated on the substrate 21 will be described with reference to FIG. Substrate 2
1 is formed using a substantially rectangular plate-like member made of an insulating material such as an insulating ceramic such as alumina or a synthetic resin. A plurality of electrodes 27a to 27d and 27e to 27h are formed on the upper surface of the substrate 21 by patterning a conductive material such as Cu or Al. The electrodes 27a to 27d and 27e to 27h are electrically connected to one of the piezoelectric resonators 22 to 25, respectively, as described later.

Also, as shown in FIG.
7 a to 27 d and 27 e to 27 h are appropriately electrically connected on the substrate 21. These electrodes 27a to 27h
The electrical connection between them is performed so as to constitute a ladder-type filter circuit described later.

On the substrate 21, a rectangular frame-shaped insulating film 28 shown schematically in FIG. The insulating film 28 is composed of a thin synthetic resin film,
In that case, an insulating adhesive (not shown) is provided on the substrate 21.
Are bonded together. Alternatively, the insulating film 28 may be formed by applying and curing an insulating adhesive on the substrate 21 so as to have the same planar shape as the insulating film 28. The planar shape of the insulating film 28 is such that the resonance electrode on the lower surface of the piezoelectric resonator 22
It is formed so as to prevent electrical connection to an electrode that should not be connected among 7a to 27h.

The piezoelectric resonator 22 has a rectangular piezoelectric substrate 22a.
Has a structure in which resonance electrodes 22b and 22c are formed on the upper surface and the lower surface. The piezoelectric substrate 22a can be formed using a piezoelectric ceramic such as a lead zirconate titanate-based piezoelectric ceramic, or a piezoelectric single crystal such as quartz or LiTaO ₃ .

Further, since the width expansion mode is used, the ratio b / a of the long side b to the short side a of the piezoelectric substrate 22a is within a range of ± 10% around a value satisfying the above-mentioned equation (1). It is determined to be within.

Since the piezoelectric resonator 22 forms a series arm resonator in a ladder type filter, the resonance electrode 22
The capacitance between b and 22c is relatively small.
Therefore, the piezoelectric substrate 22a is formed of a relatively thick substrate, and the resonance electrodes 22b and 22c are
The central electrode is formed partially in the central region of the line a, whereby the facing area between the resonance electrodes 22b and 22c is reduced.

The conductor 31 is connected to the resonance electrode 22b.
The conductor 32 is connected to the resonance electrode 22c. Like the piezoelectric resonator 22, the piezoelectric resonator 23 is a piezoelectric resonator utilizing a width expansion mode, and has a resonance electrode 23b on the entire upper surface of a rectangular piezoelectric substrate 23a and a resonance electrode 2 on the entire lower surface.
3c is formed. The piezoelectric substrate 23a can be made of the same material as the piezoelectric substrate 22a.

The piezoelectric resonator 23 is used to constitute a parallel resonator of a ladder type filter. Therefore, it is required that the capacitance between the resonance electrodes 23b and 23c is relatively large. Therefore, the thickness of the piezoelectric substrate 23a is relatively thin, and the resonance electrodes 23b and 23c are formed on the entire upper and lower surfaces of the piezoelectric substrate 23a.

A conductor 33 described later is provided on the resonance electrode 23b.
A conductor 34 described later is electrically connected to the resonance electrode 23c. The piezoelectric resonator 24 constitutes a parallel arm resonator of a ladder-type filter, and is configured similarly to the piezoelectric resonator 23. That is, the thin piezoelectric substrate 2
A resonance electrode 24b is formed on the entire upper surface of 4a, and a resonance electrode 24c is also formed on the entire lower surface.

The resonance electrodes 24b and 24c respectively have
The conductors 35 and 36 are electrically connected. The piezoelectric resonator 25 is used to form a series arm resonator of a ladder type filter, and has the same configuration as the piezoelectric resonator 22. That is, the relatively thick piezoelectric substrate 25a
, A resonance electrode 25b is formed partially.
Further, as schematically shown on the right side of FIG.
The resonance electrode 25c is also formed partially on the lower surface of the substrate a. A conductor 37 is connected to the resonance electrode 25b, and a conductor 38 is connected to the resonance electrode 25c.

The feature of the ladder type filter of this embodiment is that after the insulating film 28 is laminated on the substrate 21 shown in FIG.
That is, they are laminated and integrated by using ３９39c. That is, the piezoelectric resonator 22 is formed on the substrate 21 by the elastic resin material 39a.
To 39c, and each piezoelectric resonator 2
The portions between 2 and 25 are also joined using the elastic resin materials 39a to 39c. The elastic resin members 39a to 39c are
It is used for mechanically supporting the piezoelectric resonators 2 to 25, a function of preventing a short circuit between the upper and lower piezoelectric resonators and between the substrate and the piezoelectric resonator 22, and a function of vertically vibrating the piezoelectric resonators 22 to 25. It also has a function of providing a space for preventing the space. Therefore, the elastic resin materials 39a to 39c are applied so as to have a thickness necessary for providing a space for not hindering vibration of the upper and lower piezoelectric resonators.

The elastic resin members 39a to 39c are
Tensile strength is 15-45kgf / cm ^TwoMaterials in the range
And the elastic resin materials 39a to 39c
The sum is in the range of 5 to 48% or less of the area of the main surface of the piezoelectric resonator.
Is applied to the main surface of the piezoelectric resonator so that
You. That is, it is provided on the upper surface of the piezoelectric resonator 22.
The sum of the application areas of the plurality of elastic resin materials 39a to 39c is
The area is 5 to 48% of the area of the main surface of the piezoelectric resonator 22.
ing.

Further, in this embodiment, the elastic resin material 39a
39c are given at or near nodes of vibration of the piezoelectric resonators 22 to 25. For example, the elastic resin material 39a illustrated on the upper surface of the piezoelectric resonator 22 is provided at the center of the upper surface of the piezoelectric resonator 22 with elastic resin materials 39b and 39c.
Is provided at the center of the short side of the upper surface of the piezoelectric resonator 22. The nodes of vibration of the piezoelectric resonators 22 to 25 using the width expansion mode are the piezoelectric plates 22a to 22a.
It should be pointed out that the presence of 5a at the center of the main surface and the center of both side surfaces on the short side has been known before the filing of the present application as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-154195.

The elastic resin members 39a to 39c are also provided on the upper surface of the piezoelectric resonator 25 in order to provide an appropriate damping effect and suppress unnecessary spurious. In the ladder filter according to the present embodiment, the resonance electrodes 22b to 25c of the piezoelectric resonators 22 to 25 are connected to the conductors 3 described above.
1 to 38 are joined to appropriate ones of the electrodes 27a to 27h on the substrate 21 (see FIGS. 2 and 3) to form a four-element two-stage ladder filter shown in FIG.

In the ladder filter of this embodiment, the substrate 2
1, the four piezoelectric resonators 22 to 25 are laminated via the elastic resin materials 39 a to 39 c, so that when supporting the plurality of piezoelectric resonators 22 to 25, a complicated shape such as a spring terminal is used. No member is required. Moreover, since the elastic resin materials 39a to 39c have the above specific tensile strength and are provided at the above specific ratio to the main surface of the piezoelectric resonator, a ladder filter having desired characteristics is obtained. And the mechanical impact resistance is also effectively increased. This will be described based on specific experimental examples.

If the application area of the elastic resin material to the main surface of the piezoelectric resonator is too large, the electrical characteristics of the piezoelectric resonator, particularly the resonance frequency and the antiresonance frequency, greatly change from those of the resonator alone. Was allowed to do so. In the case of a ladder filter, when the frequency characteristics of one piezoelectric resonator deviate from the frequency characteristics of another piezoelectric resonator, waveform distortion called ripple occurs in the filter waveform characteristics. FIG. 7 shows the relationship between the frequency shift and the ripple of the piezoelectric resonator.

FIG. 7 shows the amount of frequency deviation and the amount of generated ripple when the frequency characteristic of one piezoelectric resonator deviates from the frequencies of the other three piezoelectric resonators in the two-stage four-element ladder filter. It shows the relationship between
It is preferable that the ripple is small, but it is generally strongly required that the ripple be 1 dB or less. Therefore, it can be seen from FIG. 7 that the fluctuation amount of the frequency must be 0.5 kHz or less.

On the other hand, the present inventor uses various silicone adhesives as the elastic resin material to achieve various tensile strengths, and changes the application area ratio of the elastic resin material to the main surface of the piezoelectric resonator to change the frequency. The change was measured. FIG. 8 shows the results. 8, the tensile strength was 10, 24, 3
Silicone adhesives of 0, 38, 45 and 51 kgf / cm ² were used as the elastic resin material. The area ratio is 1
Indicates the ratio (%) of the application area of the elastic resin material applied to the main surface of each of the piezoelectric resonators, and indicates a frequency change (kHz).
Indicates a deviation from the frequency characteristic (a variation amount of the resonance frequency or the anti-resonance frequency) of the piezoelectric resonator alone.

As is clear from FIG. 8, the tensile strength is 10
Regardless of the elastic resin material used in the range of up to 51 kgf / cm ² , the frequency change increases as the application area increases, and the frequency change decreases to −0.5 kHz.
It is understood that the upper limit of the application area should be set to 48% in order to make the following. That is, the application area ratio of the elastic resin material is 48%.
Is exceeded, the frequency change is −0.1 even when an elastic resin material having a tensile strength of 10 kgf / cm ² is used.
It turns out that it becomes larger than 5 kHz and the ripple becomes a magnitude that cannot be ignored.

On the other hand, electronic components are generally required to be able to withstand an impact force G of 3000 G in terms of mechanical shock resistance. When the gravitational acceleration is g, the tensile strength is T, the impact resistance is G, and the minimum required area of the elastic resin material is A, the area ratio (%) is expressed by the following equation (2).

[0047]

(Equation 2)

Therefore, for example, in the ladder-type filter of this embodiment, the mass m of the piezoelectric resonator is 200 mg,
The area S of the main surface of the piezoelectric resonator to which the elastic resin material is applied is 2
If it is 4 mm ² , a curve B indicating the lower limit in FIG. 9 is obtained. That is, this curve B shows the lower limit capable of having sufficient impact resistance, and the curve C showing the upper limit shown in FIG. 9 is the upper limit of the area ratio obtained from the results shown in FIG. Therefore, if the area ratio and the tensile strength of the elastic resin material are set so as to form a hatched area surrounded by the hatched lines between the curves B and C, a stable characteristic in which ripple is unlikely to occur is obtained. It can be seen that a ladder filter can be configured.

FIG. 10 shows the filter characteristics of the ladder type filter constructed in the same manner as in the above embodiment except that the area ratio and the tensile strength of the elastic resin material are within the above ranges, and the ladder type filter of this embodiment. It is a figure showing the filter characteristic of a filter. In FIG. 10, the solid line shows the characteristics of the ladder-type filter prepared for comparison, and the broken line shows the characteristics of the ladder-type filter of this embodiment.

Second Embodiment Although the first embodiment is applied to a ladder-type filter, the piezoelectric resonator according to the present invention may be a piezoelectric resonator using a single piezoelectric resonator. It is also possible to use a spread mode of a square plate. FIG.
FIG. 1 is an exploded perspective view for explaining a piezoelectric resonator according to a second embodiment of the present invention. Here, a piezoelectric resonator 41 using a square plate expansion mode is used.

As shown in FIG. 11, the substrate 42 is made of an insulating material such as alumina, and has a terminal electrode 43a,
43b. In addition, a rectangular frame-shaped insulating resin film 44 is bonded onto the substrate 42 using an insulating adhesive (not shown). Instead of the insulating resin film 44, the insulating resin film 44 may be omitted by applying and curing an insulating adhesive in a rectangular frame shape.

The piezoelectric resonator 41 has resonance electrodes 46 a and 46 on the entire upper and lower surfaces of a piezoelectric plate 45 having a square planar shape.
b. Further, the piezoelectric plate 45 is made of a piezoelectric ceramic such as a lead zirconate titanate-based piezoelectric ceramic which is polarized in a thickness direction.

A lead wire 47 is joined to the resonance electrode 46a, and a lead wire 48 is joined to the resonance electrode 46b. The lead wires 47 and 48 are connected to the terminal electrodes 43a and 43 on the substrate 42, respectively.
b.

The piezoelectric resonator 41 is made of elastic resin materials 49a-4
9e, it is fixed on the substrate 42. Elastic resin material 4
The elastic resin material 49a is provided at the center of the lower surface of the piezoelectric plate 45 among 9a to 49e. The remaining elastic resin material 49b ~
49e is applied to the lower surface of the piezoelectric plate 45 at a position close to the center of the side surface.

In the spreading mode of the square plate, the vibration node is located at the center of both principal surfaces, and the vicinity of the center of the side surface is a portion where displacement is as small as the vibration node. Therefore, by using the elastic resin materials 49a to 49e, the piezoelectric resonator 41 is
Even if it is fixed on 2, the resonance characteristics are not significantly affected. Moreover, in this embodiment, the elastic resin materials 49a to 49
e is used so as to have the above specific tensile strength and the above specific application area ratio, as in the first embodiment.
In this case, the applied area ratio is determined such that the total of the applied portions of the elastic resin materials 49a to 49e satisfies the area ratio of the above characteristic with respect to the area of the lower surface of the piezoelectric plate 45. In addition, 5
Reference numeral 0 denotes a metal cap, which is fixed to the substrate 42 with an insulating adhesive.

Modified Example FIG. 12 is a view for explaining an example of an application pattern when an elastic resin material is applied to a piezoelectric resonator using a width expansion mode, as shown in FIG. In addition, the elastic resin materials 51a to 51c may be arranged at three places near the center of the main surface of the piezoelectric resonator 52 using the width expansion mode and near the side surface on the short side, as shown in FIG. As described above, the elastic resin material 53 may be provided only around the node portion at the center of the main surface.

In the case of a piezoelectric resonator utilizing the expansion mode of a square plate, as shown in FIG. 13A, an elastic resin material 55 is applied only to the central node of the main surface of the piezoelectric resonator 54. Alternatively, as shown in FIG.
The elastic resin material 56a may be arranged at the vibration node at the center of the main surface, and the elastic resin materials 56b to 56e may be arranged on the main surface near the center of the side surface.

[0058]

In the piezoelectric resonator according to the present invention, the tensile strength of the elastic resin material is set to 15 to 45 kgf / cm ² , and the area ratio of the elastic resin material to the main surface of the piezoelectric resonator is 5%. Therefore, in a piezoelectric resonator having a simplified support structure using an elastic resin material, fluctuations in the characteristics of the piezoelectric resonator can be reduced and mechanical shock resistance can be increased. obtain. Therefore, it is possible to stably provide a piezoelectric resonator having desired characteristics, which is easy to manufacture and excellent in mechanical shock resistance.

Further, when the elastic resin material is applied at or near the node of vibration, fluctuations in the characteristics of the piezoelectric resonator can be more effectively prevented. In the ladder-type filter according to the present invention, a plurality of piezoelectric resonators constituting the series arm resonator and the parallel arm resonator are laminated and integrated in the thickness direction via an elastic resin material, and the elastic resin material is Since it has a specific tensile strength and is applied at a rate of 5 to 48% with respect to the main surface of the piezoelectric resonator, not only the simplification of the supporting structure but also the It is possible to easily provide a ladder-type filter having excellent filter characteristics and excellent mechanical shock resistance.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view for explaining a conventional ladder-type filter.

FIG. 2 is an exploded perspective view for explaining a ladder-type filter according to the first embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of the ladder-type filter according to the first embodiment of the present invention.

FIG. 4 is an exploded perspective view for explaining each piezoelectric resonator and an elastic resin material in the ladder filter according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a circuit configuration of a ladder-type filter according to the first embodiment of the present invention.

FIG. 6 is a perspective view showing the appearance of a ladder-type filter according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a frequency shift of resonance characteristics of one of the plurality of piezoelectric resonators and a magnitude of a ripple appearing in a ladder-type filter.

FIG. 8 is a diagram showing a relationship between an applied area ratio of an elastic resin material to a piezoelectric resonator and an amount of frequency change of the piezoelectric resonator when elastic resin materials having various tensile strengths are used.

FIG. 9 is a diagram showing a relationship between the tensile strength of the elastic resin material and the area ratio of the elastic resin material.

FIG. 10 is a diagram for explaining the filter characteristics of the first embodiment of the present invention and a ladder-type filter prepared for comparison.

FIG. 11 is an exploded perspective view illustrating a piezoelectric resonator according to a second embodiment of the present invention.

FIGS. 12A and 12B are plan views each showing an application pattern of an elastic resin material applied to a piezoelectric resonator using a width expansion mode.

FIGS. 13A and 13B are plan views for explaining a pattern of applying an elastic resin material to a piezoelectric resonator using a spreading mode of a square plate.

[Explanation of symbols]

 22-25 Piezoelectric resonators 39a-39c Elastic resin material 41 Piezoelectric resonators 49a-49e Elastic resin material 51 Piezoelectric resonators 52a-52c, 53 using elastic mode 52 Elastic resin material 54 Spread mode Piezoelectric resonator 55, 55a to 55e using elastic resin material

Claims (3)

[Claims] 1. A piezoelectric resonance device having a piezoelectric resonator using an area vibration mode supported by an elastic resin material, wherein the elastic resin material has a tensile strength of 15 to 45 kgf / cm ^2.
And the piezoelectric resonator is provided on the main surface of the resonator in a range of 5% to 48% of the area of the main surface. 2. The piezoelectric resonance device according to claim 1, wherein the elastic resin material is provided at or near a vibration node of the piezoelectric resonator. 3. A ladder-type filter having at least one parallel arm resonator and at least one series arm resonator, wherein a plurality of piezoelectric resonators constituting the series arm resonator and the parallel arm resonator are provided. The elastic resin material is laminated and integrated in the thickness direction via an elastic resin material, and the elastic resin material has a tensile strength of 15 to 45 kgf / cm.
² and the elastic resin material is 5% of the main surface of the piezoelectric resonator.
As described above, the ladder filter is bonded to the main surface of the piezoelectric resonator at a rate of 48% or less.