JP3760760B2 - Composite material vibration device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composite material vibration device having a structure capable of holding various vibration members without affecting the vibration of the vibration member, for example, a composite material vibration using a piezoelectric element or an electrostrictive element as the vibration member. Relates to the device.
[0002]
[Prior art]
Conventionally, piezoelectric vibration parts have been widely used for resonators, filters, and the like. For example, in a piezoelectric resonator, various vibration modes are used to obtain a target resonance frequency. As these vibration modes, thickness longitudinal vibration, thickness shear vibration, length vibration, width vibration, spread vibration, bending vibration, or the like is known.
[0003]
In the piezoelectric resonator, the holding structure differs depending on the type of vibration mode. When thickness longitudinal vibration or thickness shear vibration is used, an energy confining type piezoelectric resonator can be formed, and therefore the piezoelectric resonator can be mechanically held at the end of the piezoelectric resonator. FIG. 33 shows an example of an energy confinement type piezoelectric resonator using this type of thickness shear vibration. In the piezoelectric resonator 201, the resonance electrode 203 is formed on the upper surface of the strip-shaped piezoelectric plate 202, and the resonance electrode 204 is formed on the lower surface of the piezoelectric plate 202 so as to face the resonance electrode 203. The resonant electrodes 203 and 204 are opposed to each other at the center in the length direction of the piezoelectric plate 202, and the opposed portion constitutes an energy confining type piezoelectric vibrating portion. Since it is an energy confinement type, the vibration is almost confined in the piezoelectric vibration part. Therefore, the piezoelectric resonance electrode 201 can be mechanically held at the end portion without inhibiting the vibration of the piezoelectric vibration portion.
[0004]
However, in the energy confinement type piezoelectric resonance electrode 201, although vibration energy is confined in the piezoelectric vibration part, a vibration damping part having a relatively large area must be formed outside the piezoelectric vibration part. Therefore, for example, in the strip-shaped piezoelectric resonator 201 using the thickness shear mode, the length dimension has to be increased.
[0005]
On the other hand, a piezoelectric resonator using length vibration, width vibration, spread vibration, or flexural vibration cannot form an energy confining type piezoelectric resonator. Accordingly, in order not to affect the resonance characteristics, a metal terminal having a spring property is used, and the holding structure is configured by bringing the metal terminal into contact with a vibration node of the piezoelectric resonator.
[0006]
On the other hand, Japanese Patent Laid-Open No. 10-270979 discloses a bulk acoustic wave filter 211 shown in FIG. In the bulk acoustic wave filter 211, the filter is configured by laminating a plurality of films on the substrate 212. That is, a piezoelectric layer 213 is formed in this laminated structure, and electrodes 214 and 215 are laminated on the upper and lower surfaces of the piezoelectric layer 213 to form a piezoelectric resonator. On the lower surface of the piezoelectric resonator, an acoustic mirror 219 having a laminated structure including an upper layer 216, a middle layer 217, and a lower layer 218 is formed by laminating films such as silicon and polysilicon. Here, the acoustic impedance of the middle layer 217 is set higher than that of the upper layer 216 and the lower layer 218. The acoustic mirror 219 is supposed to block the vibration generated by the piezoelectric resonator from being transmitted to the substrate 212.
[0007]
On the other hand, a similarly configured acoustic mirror 220 is stacked above the piezoelectric resonator, and a passivation film 221 is formed on the acoustic mirror 220. The passivation film 221 is made of epoxy, SiO.₂Or it is comprised with the other suitable protective material.
[0008]
[Problems to be solved by the invention]
In the conventional energy confinement type piezoelectric resonator, since it is necessary to form a vibration damping portion outside the piezoelectric vibration portion, the size of the piezoelectric resonator 201 is large although it can be mechanically held using an adhesive or the like. I had to be.
[0009]
On the other hand, in the non-energy confining type piezoelectric resonator using the length vibration mode and the spreading vibration mode, the vibration damping part is not necessary, but the piezoelectric resonator itself is fixed and held using an adhesive or solder. The resonance characteristics are impaired. Therefore, it must be supported using a spring terminal or the like, the support structure is complicated, and a large number of parts are required.
[0010]
In the bulk acoustic wave filter described in JP-A-10-270979, the piezoelectric resonator and the piezoelectric resonator and the substrate are acoustically insulated by stacking a plurality of films on the substrate 202 as described above. An acoustic mirror 119 is configured. Therefore, the piezoelectric resonator is acoustically cut off and supported by the acoustic mirror 219 having a laminated structure with respect to the substrate 212.
[0011]
However, in the bulk acoustic wave filter 211, a large number of layers are stacked on the substrate 212, and a lower acoustic mirror 219, a stacked structure that forms a piezoelectric resonator or a piezoelectric filter, and a large number that forms an upper acoustic mirror 220. The passivation layer 221 must be formed on the top. Therefore, the structure is complicated, and the vibration mode in the piezoelectric resonator to be used is also limited because it is composed of a laminated structure.
[0012]
As described above, in order to support a vibration source such as a piezoelectric resonator without hindering its vibration characteristics, there are restrictions on vibration modes, parts are enlarged, and the structure is complicated. There was a problem.
[0013]
The object of the present invention is to solve the above-mentioned drawbacks of the prior art and to support a vibration member of various modes with a relatively simple structure and hardly affecting the vibration characteristics of the vibration member. It is providing the composite material vibration apparatus provided with.
[0014]
[Means for Solving the Problems]
  According to a wide aspect of the present invention, there is provided a composite material vibration device in which a plurality of material portions having different acoustic impedances are coupled, wherein the first acoustic impedance value Z₁A vibration member made of a material having a vibration source,First and second vibrating electrodes formed on the vibrating member;Acoustic impedance value Z of 2₂And a first reflection layer and a second reflection layer connected to both sides of the vibration member.The secondAcoustic impedance value Z of 3_ThreeAnd is connected to the opposite side of the first and second reflective layers to which the vibrating member is connected.1st and 2ndHolding member andAre connected to the first and second excitation electrodes formed on the vibrating member, respectively, and reach the first and second holding members through the surfaces of the first and second reflective layers, respectively. Formed first and second terminal electrodes;WithSaid second acoustic impedance value Z ₂ First acoustic impedance value Z of ₁ Ratio Z to ₂ / Z ₁ Is not more than 0.2, and the second acoustic impedance value Z ₂ The third acoustic impedance Z _Three Ratio Z to ₂ / Z _Three Is 0.2 or less,There is provided a composite material vibration device configured to reflect vibration propagating from the vibration member to the reflection layer at an interface between the reflection layer and the holding member.
[0017]
In a limited aspect of the present invention, an electromechanical coupling conversion element is used as the vibration member, and in a more limited aspect, a piezoelectric element or an electrostrictive element is used as the electromechanical coupling conversion element.
[0018]
In another specific aspect of the present invention, a third reflective layer, a first reflective layer on the opposite side of the first and / or second holding member to the side to which the first and second reflective layers are connected. The two vibration members, the fourth reflection layer, and the third holding member are connected in this order.
[0019]
  According to another broad aspect of the present invention, there is provided a composite material vibration device in which a plurality of material portions having different acoustic impedances are combined, and the first acoustic impedance value Z₁A first vibration member and a second vibration member that are vibration sources;First and second excitation electrodes formed on the first and second vibrating members;Acoustic impedance value Z of 2₂Made of material having1st to 3rdWith reflective layerThe second3 acoustic impedance Z_ThreeMade of material having1st and 2ndHolding memberWhenThe first holding member, the first reflective layer, the first vibrating member, the second reflective layer, the second vibrating member, the third reflective layer, and the second holding member are connected in this order. AndThe first and second holding members are connected to first and second excitation electrodes formed on the first and second vibrating members, respectively, and pass through the surfaces of the first and third reflective layers, respectively. Further comprising first and second terminal electrodes formed to reach the second acoustic impedance value Z ₂ First acoustic impedance value Z of ₁ Ratio Z to ₂ / Z ₁ Is not more than 0.2, and the second acoustic impedance value Z ₂ The third acoustic impedance Z _Three Ratio Z to ₂ / Z _Three Is 0.2 or less,Each vibration generated in the first and second vibrating members is caused by the interface between the first or third reflective layer and the first or second holding member, and the second vibration of the second reflective layer. A composite material vibration device is provided that is reflected by an interface with the member or the first vibration member.
[0020]
In another specific aspect of the present invention, the reflective layer is configured by laminating a plurality of material layers having different acoustic impedances.
In another specific aspect of the present invention, when the vibration wavelength when the vibration member vibrates alone is λ, the distance from the interface between the reflection layer and the vibration member to the interface between the reflection layer and the holding member is The distance is configured to be in a range of n · λ / 4 ± λ / 8 (n is an odd number).
[0021]
  In the composite material vibration device according to the present invention, when the vibration displacement direction A of the vibration member, the vibration propagation direction B of the vibration member, and the vibration propagation direction C of the reflection layer are used, the directions A to C can be variously combined. it can. For example, the directions A to C may be parallel to each other. Further, the direction A and the direction B may be parallel, and the direction B and the direction C may be orthogonal to each other. Furthermore, the direction A and the direction B may be orthogonal, and the direction B and the direction C may be parallel. Further, the direction A and the direction B may be orthogonal, and the direction B and the direction C may be orthogonal.
The mounting structure of the composite material vibration device according to the present invention further includes a mounting substrate on which the composite material vibration device configured according to the present invention is mounted, and the first and second terminal electrodes reaching the holding member Is bonded to the mounting substrate.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail by describing specific embodiments of the present invention with reference to the drawings.
[0023]
FIGS. 1A and 1B are a perspective view and a longitudinal sectional view showing a piezoelectric resonator as a composite material vibration device according to an embodiment of the present invention.
The piezoelectric resonator 1 includes a strip-shaped piezoelectric element 2 as a vibrating member, reflection layers 3 and 4 connected to both ends of the piezoelectric element 2 in the length direction, and a holding member connected to the outside of the reflection layers 3 and 4. 5 and 6.
[0024]
The piezoelectric element 2 is made of a lead titanate ceramic, and its acoustic impedance Z₁Is 3.4 × 10⁷kg / (m²S). The piezoelectric element 2 is polarized in the arrow P direction, that is, in the length direction.
[0025]
The piezoelectric element 2 has a strip shape, and an upper surface, a lower surface, and a pair of side surfaces have a rectangular shape. In other words, the piezoelectric element 2 has a square bar shape. Excitation electrodes 7 and 8 are formed on a pair of opposing end faces 2a and 2b of the piezoelectric element 2. By applying an AC voltage from the excitation electrodes 7 and 8, the piezoelectric element 2 vibrates in a length mode in which the end surfaces 2a and 2b are in the length direction. That is, the piezoelectric element 2 is a piezoelectric resonance element using a length mode. In the piezoelectric resonator 1, terminal electrodes 9 and 10 are formed on the upper surface of the piezoelectric resonator 1 so as to be electrically connected to the excitation electrodes 7 and 8. The terminal electrodes 9 and 10 are formed not only on the upper surface of the piezoelectric resonator 1 but also on the outer end surfaces 5a and 6a of the holding members 5 and 6 which are end surfaces. Therefore, surface mounting can be easily performed on a printed circuit board or the like by using the terminal electrodes 9 and 10. In this embodiment, the reflection layers 3 and 4 have an acoustic impedance of 1.87 × 10 6.⁶kg / (m²-It is comprised with the epoxy resin which is s). The holding members 5 and 6 have an acoustic impedance of 3.4 × 10.⁷kg / (m²-It is comprised with the ceramic which consists of ceramics which are s).
[0026]
In the piezoelectric resonant element using the length mode, since the propagation direction of vibration is the length direction and is parallel to the polarization direction P, it is usually supported on the end faces 2a and 2b without affecting the vibration. I can't.
[0027]
In this embodiment, since the reflecting layers 3 and 4 and the holding members 5 and 6 are provided, the piezoelectric resonator 1 can be supported without affecting the vibration characteristics of the piezoelectric element 2 using the length mode. ing. This will be described with reference to FIGS. In the following, the length means a dimension along the length direction of the piezoelectric resonator 1.
[0028]
Length L of piezoelectric element 2₁= 0.98 mm, resonator frequency F₁= 2 MHz, length L of the reflective layers 3 and 4₂The displacement state of the piezoelectric resonator 1 was analyzed by the finite element method with = 0.25 mm and the length of the holding members 5 and 6 = 0.4 mm. The results are shown in FIG.
[0029]
As apparent from FIG. 2, the holding members 5 and 6 are hardly displaced. Therefore, it can be seen that the holding member 5 and 6 can be used to support the piezoelectric resonator 1 without affecting the resonance characteristics of the piezoelectric element 2. This is the acoustic impedance Z of the reflective layers 3 and 4₂Is the acoustic impedance Z of the piezoelectric element 2₁Lower than the acoustic impedance Z of the holding members 5 and 6_ThreeThis is because the vibration propagated from the piezoelectric element 2 is reflected at the interfaces A and B between the reflective layers 3 and 4 and the holding members 5 and 6, and the vibration hardly propagates to the holding members 5 and 6. .
[0030]
In view of the result of the piezoelectric resonator 1, the inventors of the present application conducted experiments by changing the materials constituting the piezoelectric element 2, the reflective layers 3, 4 and the holding members 5, 6 in the piezoelectric resonator 1 and their dimensions in various ways. Repeatedly, as described above, the acoustic impedance Z of the first and second reflective layers 3 and 4₂, The acoustic impedance Z of the piezoelectric element 2₁And the acoustic impedance Z of the holding members 5 and 6_ThreeIt has been found that the propagation of vibration from the piezoelectric element 2 to the holding members 5 and 6 can be substantially suppressed as in the case of the above embodiment. This will be described based on a specific experimental example with reference to FIG. 4 and FIG.
[0031]
FIG. 4 shows impedance-frequency characteristics and phase-frequency characteristics when the piezoelectric resonator 1 is configured with the following specifications. The solid line indicates the phase-frequency characteristic, and the broken line indicates the impedance-frequency characteristic. Further, NE + On on the vertical axis and the horizontal axis in FIGS. 4 and 5 is N × 10.ⁿFor example, 1E + O2 is 1 × 10²It is.
[0032]
Specifications of piezoelectric resonator 1
(1) Piezoelectric element 2 ... acoustic impedance Z₁= 3.4 × 10⁷kg / (m²-Consists of lead titanate ceramics s). Length dimension L₁= 412mm, resonator circumference 5.4MHZ
(2) Reflective layers 3, 4 ... Acoustic impedance Z₂= 1.87 x 10⁶kg / (m²-Consists of epoxy resin s) Length dimension L₂= 0.07mm
(3) Holding members 5, 6 ... acoustic impedance Z_Three= 3.4 × 10⁷kg / (m²-Consists of s) lead titanate-based ceramics. Length dimension L_Three= 300mm
The width direction dimension of the piezoelectric resonator 1 was 250 mm and the thickness was 200 mm.
[0033]
The piezoelectric resonator 1 was bonded and fixed to the substrate 11 using a conductive adhesive 12 as shown in FIG. Note that the bonding with the conductive adhesive 12 is performed by the conductive adhesive 12 so as to secure a space between the lower surface of the piezoelectric element 2 and the upper surface of the substrate 11 so as not to prevent vibration.
[0034]
The conductive adhesive 12 joins the terminal electrodes 9 and 10 and the electrodes 13 and 14 on the substrate 11, and the conductive adhesive 12 adheres to the piezoelectric element 2 and the reflective layers 3 and 4. Not.
[0035]
FIG. 5 shows frequency characteristics of the piezoelectric resonator 1 after being mounted on the substrate 11. Also in FIG. 5, a broken line shows an impedance-frequency characteristic, and a continuous line shows a phase-frequency characteristic.
[0036]
4 and 5 clearly show that the frequency characteristics of the piezoelectric resonator 1 itself and the frequency characteristics of the piezoelectric resonator 1 after being fixed to the substrate 11 are almost the same. That is, it can be seen that even if the piezoelectric resonator 1 is mechanically fixed by the holding members 5 and 6, the resonance characteristics of the piezoelectric element 2 are not impaired.
[0037]
As is apparent from FIGS. 1 to 5, in the piezoelectric resonator 1 as the composite material vibration device configured according to the present invention, the reflection layers 3 and 4 are provided on both sides of the piezoelectric element 2 as the vibration member. 4, the holding members 5 and 6 are connected to the outside of the piezoelectric resonator 1, so that the piezoelectric resonator 1 can be supported without disturbing the vibration of the piezoelectric element 2. When this is comprehensively shown in FIG. 6, in the composite material vibration device according to the present invention, the reflection layers 22 and 23 are provided so that the vibration from the vibration member 21 is propagated to both sides of the vibration member 21 as a vibration source. It is connected and corresponds to a structure in which holding members 24 and 25 are connected to the outside of the reflective layers 22 and 23. In this case, the acoustic impedance Z of the reflective layers 22 and 23 is as described above.₂, The acoustic impedance Z of the vibration member 21₁And the acoustic impedance Z of the holding members 24, 25_ThreeBy making it smaller, the composite material vibration device 20 can be mechanically supported by the holding members 24 and 25 without affecting the vibration characteristics of the vibration member 21 as in the above-described embodiment.
[0038]
That is, in the above embodiment, the piezoelectric element 2 is used as the vibration member. However, in the present invention, the impedance value Z of the vibration member 21, the reflection layers 22, 23, and the holding members 24, 25 is used.₁~ Z_ThreeAs long as the above relationship can be satisfied, the vibration propagated at the interface between the reflective layers 22 and 23 and the holding members 24 and 25 can be reflected as in the above embodiment. It is not limited. That is, as the vibration member 21, in addition to the piezoelectric element 2, an electrostrictive element and other members that generate various vibrations can be widely used.
[0039]
Further, the material constituting the reflective layers 22 and 23 and the material constituting the holding members 24 and 25 are not particularly limited, and any material can be used as long as the relationship of the acoustic impedance values is satisfied.
[0040]
The inventors of the present invention measured various rates of change in the resonance frequency and bandwidth of the piezoelectric resonator 1 by using different materials constituting the reflective layer in the piezoelectric resonator 1. The results are shown in FIGS. Here, the ceramics constituting the piezoelectric element 2 and the epoxy resin constituting the reflective layers 3 and 4 are varied, and the acoustic impedance Z₂The normalized value of the ratio Z₂/ Z₁The resonance frequency change rate (%) and the ratio band change rate (%) were measured.
[0041]
As apparent from FIGS. 7 and 8, the acoustic impedance ratio Z₂/ Z₁Is 0.2 or less, preferably 0.1 or less, the change rate of the resonance frequency is very small as 0.2% or less, and when 0.1 or less, it can be seen that it is as low as 0.01% or less. Similarly, the acoustic impedance ratio Z is also applied to the rate of change in the ratio band.₂/ Z₁Is -15% or less at 0.2 or less, and -8% or less at 0.1 or less.
[0042]
Therefore, preferably the acoustic impedance ratio Z₂/ Z₁Is 0.2 or less, more preferably 0.1 or less.
In addition, the inventors of the present application differed in the materials constituting the reflective layers 3 and 4 and the holding members 5 and 6, and the acoustic impedance ratio Z₂/ Z_ThreeThe frequency change rate (%) and the ratio band change rate (%) of the piezoelectric resonator 1 were measured in the same manner. The results are shown in FIGS.
[0043]
As is clear from FIGS. 9 and 10, the acoustic impedance ratio Z₂/ Z_ThreeIs 0.2% or less, the frequency change rate is 0.2% or less, the specific bandwidth is −7% or less, and further 0.1 or less is 0.05% or less, and the specific bandwidth is −6. It can be seen that it can be less than or equal to%. Therefore, the acoustic impedance ratio Z₂/ Z_ThreeIs preferably 0.2 or less, more preferably 0.1 or less.
[0044]
Also, the acoustic impedance ratio Z₂/ Z₁The resonance frequency rate and the ratio band change rate of the piezoelectric resonator 1 were measured. The results are shown in FIG. 11 and FIG. In FIGS. 11 and 12, as a material constituting the reflective layers 3 and 4, an acoustic impedance Z is obtained by blending epoxy resin, ceramics, or a powder having other acoustic impedance values with these materials.₂Is acoustic impedance Z₁1/128 to any range.
[0045]
The horizontal axis in FIGS. 11 and 12 is the dimension in the length direction of the reflective layers 3 and 4 (dimension along the length direction of the piezoelectric resonator 1). The dimension in the length direction of the reflective layers 3 and 4 is, in other words, the dimension in the direction connecting the reflective layer surface connected to the piezoelectric element 2 as the vibration member and the reflective layer surface connected to the vibration members 5 and 6. That is, it is the dimension in the direction in which vibration propagates through the reflecting surface.
[0046]
As is clear from FIGS. 11 and 12, the acoustic impedance ratio Z₂/ Z₁Is smaller than 1/32, more preferably 1/64 or less, even if the length dimension of the reflective layers 3 and 4 slightly varies from λ / 4, the frequency change rate and the ratio band change rate do not change much. I understand that. Therefore, preferably, Z₂/ Z₁It can be seen that by setting the ratio to 1/32 or less, more preferably 1/64 or less, the length dimension of the reflective layers 3 and 4 is less restricted.
[0047]
However, as is clear from FIG. 11 and FIG.₂/ Z₁Regardless of the value of, when the length of the reflective layers 3 and 4 is λ / 4 and the vicinity thereof, the frequency change rate and the specific bandwidth change rate of the piezoelectric resonator 1 are very small.
[0048]
Further, the relationship between the thickness of the reflection layers 3 and 4 and the frequency change rate and the ratio band change rate was examined over a wider thickness of the reflection layers 3 and 4. The results are shown in FIGS. 13 and 14, respectively. Accordingly, as is apparent from FIGS. 11 to 14, the length of the reflective layers 3 and 4 is preferably in the range of n · λ / 4 ± (λ / 8) (n is an odd number), and more preferably, λ / 4 and its vicinity.
[0049]
15A and 15B are a perspective view and a partially cutaway longitudinal sectional view showing a piezoelectric resonator as a composite material vibration device according to a second embodiment of the present invention.
The piezoelectric resonator 31 includes a strip-shaped or square bar-shaped piezoelectric element 32. The piezoelectric element 32 is a piezoelectric element using a sixth harmonic of a length mode. The piezoelectric resonator 31 of this embodiment is the same as that of the first embodiment except that the piezoelectric element 32 is used instead of the piezoelectric element 2 and that the electrode structure for exciting the piezoelectric element 32 is different. The piezoelectric resonator 1 is configured in the same manner.
[0050]
In the present embodiment, the piezoelectric element 32 has an acoustic impedance value of 2.6 × 10.⁷kg / (m²-It is comprised by the lead zirconate titanate type piezoelectric ceramic of s).
[0051]
In the piezoelectric element 32, six excitation electrodes 32 a to 32 f extending in the cross-sectional direction of the piezoelectric element 32 are formed in order to excite the sixth harmonic of the length mode. In other words, the excitation electrodes 32 a to 32 f are formed in parallel to each other and in the transverse direction of the piezoelectric resonator 32 so that five piezoelectric layers exist between the excitation electrodes 32 a to 23 f. The five piezoelectric layers are uniformly polarized in the length direction.
[0052]
A terminal electrode 37 is formed on the upper surface of the piezoelectric resonator 31 so as to be electrically connected to the excitation electrodes 32a, 32c, and 32e. A terminal electrode 38 is formed on the lower surface of the piezoelectric resonator 31, and is electrically connected to the excitation electrodes 32b, 32d, and 32f.
[0053]
In order to electrically insulate the excitation electrodes 32b, 32d, and 32f from the terminal electrode 37, insulating materials 39a to 39c are applied to the upper ends of the excitation electrodes 32b, 32d, and 32f. Similarly, in order to achieve electrical insulation between the excitation electrodes 32a, 32c and 32e and the terminal electrode 38, insulating materials 39d to 39f are disposed at the lower ends of the excitation electrodes 32a, 32c and 32e.
[0054]
The reflection layers 33 and 34 are located at both ends of the piezoelectric element 32 in the length direction, and the acoustic impedance ratio Z₂/ Z₁= 1/16 of epoxy resin.
[0055]
On the outside of the reflective layers 33 and 34, an acoustic impedance ratio Z₂/ Z_ThreeThe holding members 35 and 36 made of lead zirconate titanate ceramics satisfying 1/16 are connected.
[0056]
The terminal electrodes 37 and 38 are formed so as to reach the opposing end surfaces of the piezoelectric resonator 31, that is, the outer end surfaces 35 a and 36 a of the holding members 35 and 36.
Also in the present embodiment, the cross-sectional shapes of the reflective layers 33 and 34 and the holding members 35 and 36 are the same as those of the piezoelectric element 32. Accordingly, the piezoelectric resonator 31 has a square bar shape.
[0057]
As in the second embodiment, the piezoelectric element 32 as the vibration member may use a harmonic in a length mode.
The impedance-frequency characteristics and phase-frequency characteristics of the piezoelectric resonator 31 are shown in FIG. Also, as shown in FIG. 16, the impedance-frequency characteristics and phase-frequency characteristics after the piezoelectric resonator 31 is bonded and fixed on the mounting substrate 41 using the conductive adhesives 42, 43 are shown in FIG. . 17 and 18, the solid line indicates the phase-frequency characteristic, and the broken line indicates the impedance-frequency characteristic.
[0058]
As apparent from the comparison between FIGS. 17 and 18, also in the second embodiment, the characteristics before being mounted on the mounting substrate 41 (that is, the piezoelectric resonator 31 alone) and after being mounted on the mounting substrate 41. It can be seen that the characteristics hardly change.
[0059]
Therefore, also in the second embodiment, it can be seen that even if the piezoelectric resonator 31 is mechanically held by the holding members 35 and 36, the resonance characteristics of the piezoelectric element 32 are hardly affected.
[0060]
As shown in an exploded perspective view in FIG. 19, a plurality of piezoelectric resonators 31 may be bonded via insulating adhesives 51 and 52 and mounted on the mounting substrate 53. In the structure shown in FIG. 19, two piezoelectric resonators 31 and 31 are joined and electrically connected to form a filter circuit. Electrical connection between the two piezoelectric resonators 31 is achieved by the conductive patterns 54 a to 54 d formed on the mounting substrate 53. A metal cap 55 is fixed on the mounting substrate 53. The metal cap 55 is fixed to the mounting substrate 53 using an insulating adhesive so as to surround and seal the piezoelectric resonators 31 and 31. Like the filter component shown in FIG. 19, the composite material vibration device according to the present invention can be applied not only to a piezoelectric resonator but also to a filter.
[0061]
FIG. 20 is a perspective view showing a piezoelectric resonator according to a third embodiment of the present invention. The piezoelectric resonator 61 includes a piezoelectric element 62 using a thickness shear mode. In this embodiment, the piezoelectric element 62 has a rectangular plate shape made of piezoelectric ceramics, and an excitation electrode 63 is formed on the upper surface and an excitation electrode 64 is formed on the lower surface. The piezoelectric element 62 is polarized in its length direction. By applying an AC voltage from the excitation electrodes 63 and 64, the piezoelectric element 62 is excited in the thickness-shear mode.
[0062]
Unlike the conventional energy confinement type piezoelectric resonator 201 (see FIG. 33) using the thickness shear mode, the piezoelectric element 62 has excitation electrodes 63 and 64 formed on the entire upper and lower surfaces. Accordingly, the piezoelectric element 62 is not an energy confining type piezoelectric resonator.
[0063]
However, the reflective layers 65 and 66 and the holding members 67 and 68 are connected to both sides in the length direction of the piezoelectric element 62 as in the first embodiment. The thickness of the reflective layers 65 and 66, that is, the dimension in the direction connecting the piezoelectric element 62 and the holding members 67 and 68 is about λ / 4 when the wavelength of the propagated vibration is λ. The resonance electrodes 63 and 64 are connected to the terminal electrodes 69 and 70. The terminal electrodes 70 and 69 are formed so as to reach the end face of the piezoelectric resonator 62, that is, the outer end faces 67 a and 68 a of the holding members 67 and 68.
[0064]
In the piezoelectric resonator 61 of this embodiment, the piezoelectric element 62 is not an energy trapping type, but the reflection layers 65 and 66 and the holding members 67 and 68 are configured in the same manner as in the first embodiment. In addition, the acoustic impedance value Z of the piezoelectric element 62₁And the acoustic impedance value Z of the reflective layers 65 and 66₂And the acoustic impedance value Z of the holding members 67 and 68_ThreeIs selected in the same manner as in the first embodiment, the vibration propagated in the length direction from the piezoelectric element 62 is reflected at the interface between the reflective layers 65 and 66 and the holding members 67 and 68. Therefore, even if mechanically supported by the holding members 67 and 68 as in the first embodiment, the resonance characteristics of the piezoelectric element 62 are hardly affected. As described above, even when the thickness-slip mode is used, by using the present invention, the vibration damping portion can be eliminated, and the piezoelectric resonator using the thickness-slip mode can be downsized. .
[0065]
That is, since the thickness of the reflective layers 65 and 66 (the dimension along the length direction of the resonance 61) may be about λ / 4, a large vibration attenuating portion like the conventional energy confinement type piezoelectric resonator 201 is not required. . In addition, the holding members 67 and 68 may have a very small dimension along the length direction of the piezoelectric resonator 61 and only need to form the reflection surface. Therefore, the piezoelectric resonator 61 is connected to the piezoelectric resonator 201. In comparison, the length dimension can be reduced.
[0066]
The frequency characteristics of the piezoelectric resonator 61 of this embodiment and the frequency characteristics in a state where the piezoelectric resonator 61 is fixed on the mounting substrate 71 using the conductive adhesives 72 and 73 as shown in FIG. It was. The broken line in FIG. 22 shows the impedance-frequency characteristics, the solid line shows the phase-frequency characteristics, and FIG. 22 shows the characteristics after being mounted on the mounting board 71, but the characteristics before the mounting are hardly changed. Is omitted. The piezoelectric resonator as the composite material vibration device according to the present invention is not limited to the one using the vibration mode used in the first to third embodiments, and the vibration mode of the piezoelectric element as the vibration member is not particularly limited. .
[0067]
FIG. 23 is a schematic cross-sectional view showing a modification of the piezoelectric resonator as the composite material vibration device according to the present invention. In the piezoelectric resonator 81 shown in FIG. 23, a rectangular plate-like piezoelectric element 82 using thickness longitudinal vibration is used. Excitation electrodes 83 and 84 are formed on the upper and lower surfaces of the piezoelectric element 82 so as to face each other with the piezoelectric element 82 therebetween. Ceramic plates 87 and 88 as a holding member are laminated on the upper and lower surfaces of the piezoelectric element 82 via reflective layers 85 and 86. Terminal electrodes 89 and 90 electrically connected to the excitation electrodes 83 and 84 are formed on the outer surface of the piezoelectric resonator 81, respectively.
[0068]
A piezoelectric element using a thickness longitudinal vibration mode, such as the piezoelectric element 82, may be used as the vibration member in the present invention. Further, like the piezoelectric resonator 81, the reflective layers 83 and 84 and the holding members 87 and 88 may be stacked on the upper and lower sides of the piezoelectric element 82.
[0069]
Furthermore, the present invention can also be applied to a piezoelectric resonator using a laminated thickness longitudinal vibration mode, such as a piezoelectric resonator 91 shown in FIG. Here, the piezoelectric element 92 has internal electrodes 95 and 96 configured in the piezoelectric element 92 in addition to the excitation electrodes 93 and 94. Therefore, the piezoelectric element 92 using the harmonic of the thickness longitudinal vibration is configured. Similar to the piezoelectric resonator 81, reflection layers 83 and 84 and holding members 87 and 88 are stacked above and below the piezoelectric element 92.
[0070]
In the composite material vibration device according to the present invention, when the vibration direction of the vibration member is A, the vibration propagation direction of the vibration member is B, and the vibration propagation direction of the reflection layer is C, the combination of directions A to C is appropriately deformed. Can be done.
[0071]
That is, even if the piezoelectric resonators 101 to 103 shown in FIGS. 25A to 25C are arranged so that the direction A and the direction B are parallel and the direction B and the direction C are orthogonal to each other. Good. Each of FIGS. 25A to 25C is a piezoelectric resonator using length vibration, and each of the piezoelectric elements 101a, 101b, and 101c is polarized in the direction indicated by the arrow. Reference numeral 104a denotes a reflective layer, and 104b denotes a holding member.
[0072]
That is, in the present invention, the reflective layer may be arranged perpendicular to the vibration propagation direction in the vibration member. FIG. 26 shows the result of analyzing the displacement distribution by the finite element method having such a structure. In FIG. 26, the acoustic impedance value Z is used as the vibration member.₁Is 3.0 × 10⁷kg / (m²・ S) Piezoelectric ceramics, length L₁Is a piezoelectric element 106 using a length mode with a resonator frequency of 2 MHz. Reflective layers 107 and 108 are disposed on the side surface of the piezoelectric element 106, that is, in a direction orthogonal to the vibration propagation direction of the piezoelectric element 106. The reflective layers 107 and 108 have an acoustic impedance value Z₂1.87 × 10⁶kg / (m²S) and thickness (dimension in the direction from the interface between the piezoelectric element 106 and the reflective layers 107 and 108 to the opposite surface of the reflective layers 107 and 108) are 0.15 mm. The holding members 109 and 110 have an acoustic impedance Z_Three= 3.0 × 10⁷kg / (m²The lead zirconate titanate ceramic of s) is connected to the reflective layers 107 and 108.
[0073]
As can be seen from FIG. 26, even in the piezoelectric resonator 105, almost no vibration leaks to the holding members 109 and 110.
Therefore, in the composite material vibration device according to the present invention, the reflective layer may be coupled in a direction orthogonal to the vibration propagation direction in the vibration member. Such an example is embodied in the piezoelectric resonators 101 to 103 shown in FIGS. 25A to 25C described above.
[0074]
Further, like the piezoelectric resonators 111 and 112 schematically shown in FIGS. 27A and 27B, the vibration propagation directions (polarization indicated by arrows) of the piezoelectric elements 111a and 112a using the thickness longitudinal vibration mode. The reflective layers 113 and 114 may be arranged in a direction orthogonal to the direction parallel to the direction. Note that the piezoelectric element 112a shown in FIG. 27B is a piezoelectric resonance element using a laminated thickness longitudinal vibration having an internal electrode.
[0075]
In FIGS. 27A and 27B, reflection layers 113 and 114 are disposed on both sides of the piezoelectric elements 111a and 112a using the thickness longitudinal vibration in a direction orthogonal to the vibration propagation direction in the piezoelectric elements 111a and 112a. . Further, holding members 115 and 116 are connected to a surface opposite to the surface where the reflective layers 113 and 114 are coupled to the piezoelectric elements 111a and 112a.
[0076]
Furthermore, in the composite material vibration device according to the present invention, as in the piezoelectric resonator 117 shown in FIG. 28, the vibration displacement direction in the vibration member and the vibration propagation direction in the vibration member are orthogonal to each other, and the vibration propagation direction in the vibration member is The vibration propagation directions in the reflective layer may be parallel. The piezoelectric resonator 117 includes a piezoelectric element 117a. The piezoelectric element 117a has a structure in which excitation electrodes 118 and 119 are formed on both main surfaces of the piezoelectric ceramic, and is polarized in the paper-back direction in FIG. Therefore, the piezoelectric element 117a is a piezoelectric element using a thickness torsional vibration mode. Reflective layers 113 and 114 and holding members 115 and 116 are connected to the outside of the piezoelectric element 117a.
[0077]
As is apparent from FIGS. 25 to 28 and FIGS. 30A to 30C described later, in the present invention, the vibration displacement direction of the vibration member, the vibration propagation direction in the vibration member, and the vibration propagation direction in the reflection layer Can be configured in various relationships, and in any case, the acoustic impedance Z described above₁~ Z_ThreeAs long as the above relationship is satisfied, the piezoelectric resonator can be mechanically held by the holding member without affecting the resonance characteristics of the piezoelectric element, as in the first embodiment.
[0078]
The present invention can also be applied to other resonators and filters using the piezoelectric effect, such as surface wave devices. FIG. 29 is a plan view showing a surface wave resonator as a fourth embodiment of the composite material vibration device according to the invention. In the surface wave resonator 121, first and second interdigital transducers (IDT) 123 and 124 are arranged on a rectangular plate-shaped piezoelectric substrate 122 so as to be separated from each other in the surface wave propagation direction. The first and second reflective layers 125 and 126 are coupled to the outer side of the piezoelectric plate 122 in the surface wave propagation direction, and holding members 127 and 128 made of a ceramic plate are coupled to the outer sides of the reflective layers 125 and 126. ing. Here, the acoustic impedance value Z of the piezoelectric plate 122₁, Acoustic impedance value Z of the reflective layers 125 and 126₂And the acoustic impedance Z of the holding members 127 and 128_ThreeIs selected in the same manner as in the first embodiment, the surface wave is reflected at the interface between the reflection layers 125 and 126 and the holding members 127 and 128, and can be operated as a surface wave resonator. Therefore, since the reflector can be omitted, the surface wave resonator can be miniaturized.
[0079]
In the piezoelectric resonators 131 to 133 shown in FIGS. 30A to 30C, the vibration displacement direction A of the vibration member, the vibration propagation direction B of the vibration member, and the vibration propagation direction C of the reflection layer are orthogonal to each other. It is each schematic sectional drawing which shows the piezoelectric resonator in relation.
[0080]
In the piezoelectric resonator 131, a piezoelectric element 134 using a thickness shear mode is used. Here, the piezoelectric element 134 is polarized in the direction of the arrow shown in the figure, has excitation electrodes 135 and 136, and the vibration displacement direction A has a component parallel to the excitation electrode but also a vertical component. The vibration propagation direction B in the piezoelectric element 134 is a direction parallel to the excitation electrodes 135 and 136. On the other hand, the reflection layers 137 and 138 are connected to the lower surface of the piezoelectric element 134, and the vibration propagation direction in the reflection layers 137 and 138 is orthogonal to the vibration propagation direction in the piezoelectric element 134. The holding members 139a and 139b are connected to the surface of the reflective layers 137 and 138 opposite to the surface connected to the piezoelectric element 134.
[0081]
In FIG. 30B, a holding member 140 is used, and the holding member 140 corresponds to a structure in which the holding members 139a and 139b of FIG.
[0082]
Thus, the holding member provided outside the reflective layer may be connected to both the first and second reflective layers.
In the piezoelectric resonator 133 shown in FIG. 30 (c), a piezoelectric element 141 using thickness torsional vibration is used. The other points are the same as those of the piezoelectric resonator 1 shown in FIG.
[0083]
As described above, in the composite material vibration device according to the present invention, a piezoelectric element using various vibration modes can be used as the vibration member. However, an electrostrictive effect element may be used instead of the piezoelectric element. Good. Furthermore, not only electromechanical coupling conversion elements such as piezoelectric elements and electrostrictive elements, but also a vibration source that generates various vibrations can be used as the vibration member of the composite material vibration device according to the present invention.
[0084]
Moreover, in this invention, the connection relationship of a vibration member, a reflection layer, and a holding member is not limited to each Example and modification mentioned above. For example, as shown in FIGS. 31 (a), (b), (c) and FIG. 32, a composite material vibration device using a plurality of vibration members can be configured.
[0085]
In the composite material vibrating device shown in FIG. 31A, the first and second vibrating members 151 and 152 are connected via the reflective layer 153, and the outer sides of the first and second vibrating members 151 and 152 are connected. The reflective layers 154 and 155 and the holding members 156 and 157 are connected to each other. Here, the reflective layers 155 and 156 constitute the first and second reflective layers in the present invention, and the holding members 156 and 157 constitute the first and second holding members in the present invention. The structure in which the first and second vibrating members 151 and 152 are connected by the reflective layer 153 can be grasped as one vibrating member of the composite material vibrating device according to the present invention. In addition, since the first and second vibrating members 151 and 152 are connected via the reflective layer 153, the vibration propagated from the first vibrating member to the reflective layer 153 side is reflected between the reflective layer 153 and the second vibrating member. On the contrary, the vibration reflected from the interface with the vibration member 152 and propagated from the vibration member 152 to the reflection layer 153 is reflected at the interface between the reflection layer 153 and the first vibration member 151.
[0086]
In the composite material vibration device shown in FIG. 31 (b), the first and second reflective layers 162 and 163 are connected to both sides of the vibration member 161, and the first and second reflective layers 162 and 163 are outside. The holding members 164 and 165 are connected. That is, the structure so far is the same as that of the first embodiment. The difference is that the third reflective layer 166, the second vibrating member 167, the fourth reflective layer 168, and the third holding member 169 are connected to the outside of the second holding member 165 in this order. There is. Here, the vibration generated by the second vibrating member 169 is reflected by the interface between the reflective layers 166 and 168 and the holding members 165 and 169. That is, two composite material vibration devices according to the first embodiment are prepared, and the two composite material vibration devices are connected by serving as one holding member of both.
[0087]
In a composite material vibration device 171 shown in FIG. 32, composite material vibration devices 172 and 173 configured in the same manner as in the first embodiment are connected via a reflective layer 174.
[0088]
Further, as shown in FIG. 31 (c), the reflection layers 182 and 183 and the holding members 184 and 185 are connected to both sides of the vibration member 181. Further, the reflection layers 186 and 187 are provided outside the holding members 184 and 185, respectively. , The holding members 188 and 189 may be coupled.
[0089]
【The invention's effect】
In the composite material vibration device according to the present invention, the first and second reflection layers are connected to both sides of the vibration generation source, which is opposite to the side where the vibration members of the first and second reflection layers are connected. The first and second holding members are connected to the side, and the acoustic impedance value Z of the reflective layer₂Is the acoustic impedance value Z of the vibrating member and holding member₁, Z_ThreeTherefore, the vibration propagating from the vibrating member to the reflecting layer is reflected at the interface between the reflecting layer and the holding member. Therefore, the first and second holding members can be mechanically supported without affecting the vibration characteristics of the vibration member.
[0090]
In the present invention, the reflection layer and the holding member are connected to the vibration member as described above, and the vibration propagated to the reflection layer is reflected at the interface between the reflection layer and the holding member. The specific structure is not particularly limited. Therefore, for example, when a piezoelectric vibration element is used as a vibration member, various vibration modes such as a length vibration mode, a bending vibration mode, and a spread mode can be used, and a conventional energy confinement type piezoelectric vibration element can be configured. By utilizing the vibration mode that has not been provided, it is possible to configure a composite material vibration device that can be supported without requiring a complicated support structure such as a spring terminal.
[0091]
In addition, even in a conventional piezoelectric resonator using an energy confinement type thickness-shear mode, a vibration damping unit having a relatively large area had to be configured, whereas in the composite material vibration device according to the present invention, No need for vibration damping parts. Therefore, when the vibration mode is used, a smaller piezoelectric resonator or piezoelectric filter can be provided by using the present invention as compared with the conventional energy confinement type piezoelectric vibration element.
[0092]
  further,Acoustic impedance ratio Z₂/ Z₁Is 0.2 or lessForThe composite vibration device can be supported on the holding member with little influence on the vibration characteristics of the vibration member, and similarly the acoustic impedance ratio Z₂/ Z_ThreeIs 0.2 or lessBecauseEven if mechanically supported by the holding member, the vibration characteristics of the vibrating memberInfluenceIt can be made even smaller.
[0093]
On the opposite side of the first and / or second holding member to the side where the first and second reflective layers are connected, a third reflective layer, a second vibrating member, a fourth reflective layer, and a first reflective layer are provided. When the three holding members are connected in this order, a filter using two vibrating members can be easily configured according to the present invention. The first holding member, the first reflective layer, the first vibrating member, the second reflective layer, the second vibrating member, the third reflective layer, and the second holding member are connected in this order. Even in the composite material vibration device, the first and second holding members can be mechanically supported according to the present invention without affecting the vibration characteristics of the first and second vibration members. It is possible to provide a small piezoelectric filter, a composite piezoelectric resonance component and the like using various vibration modes.
[0094]
In the present invention, the distance from the interface of the reflective layer to the vibration member to the interface between the reflective layer and the holding member is n · λ / 4 ± λ / 8, where λ is the wavelength of the transmitted vibration. In this case, it is possible to further reduce the influence of the vibration characteristics of the vibration member when mechanical support is performed by the holding member.
[Brief description of the drawings]
1A and 1B are a perspective view and a longitudinal sectional view showing a piezoelectric resonator as a composite material vibration device according to a first embodiment of the present invention.
2 is a schematic longitudinal sectional view showing a displacement distribution analyzed by a finite element method of the piezoelectric resonator shown in FIG. 1. FIG.
FIG. 3 is a perspective view showing a state in which the piezoelectric resonator according to the first embodiment is mounted on a mounting board.
FIG. 4 is a diagram showing resonance characteristics before mounting the piezoelectric resonator according to the first embodiment on a mounting board;
FIG. 5 is a diagram showing resonance characteristics after the piezoelectric resonator according to the first embodiment is mounted on a mounting substrate;
FIG. 6 is a schematic configuration diagram of a composite material vibration device according to the present invention.
FIG. 7 shows an acoustic impedance ratio Z in the piezoelectric resonator of the first embodiment.₂/ Z₁The figure which shows the relationship between and resonance frequency change rate.
FIG. 8 shows an acoustic impedance ratio Z in the piezoelectric resonator of the first embodiment.₂/ Z₁The figure which shows the relationship between and a specific band change rate.
FIG. 9 shows an acoustic impedance ratio Z in the piezoelectric resonator of the first embodiment.₂/ Z_ThreeThe figure which shows the relationship between and resonance frequency change rate.
FIG. 10 shows an acoustic impedance ratio Z in the piezoelectric resonator of the first embodiment.₂/ Z_ThreeThe figure which shows the relationship between and a specific band change rate.
FIG. 11 is a diagram showing the relationship between the dimension of the reflection layer along the length direction of the piezoelectric resonator and the resonator frequency change rate when the reflection layer of various acoustic impedances is used.
FIG. 12 is a diagram showing the relationship between the size of the reflective layer along the length direction of the piezoelectric resonator and the rate of change in the specific band when reflective layers having various acoustic impedances are used.
FIG. 13 is a diagram showing a frequency change rate when the thickness of the reflective layer, that is, the dimension along the length direction of the piezoelectric resonator is changed.
FIG. 14 is a diagram showing a rate of change in a specific band when the thickness of the reflective layer, that is, the dimension along the length direction of the piezoelectric resonator is changed.
FIGS. 15A and 15B are a perspective view and a partially cutaway longitudinal sectional view of a piezoelectric resonator as a second embodiment of the present invention. FIGS.
FIG. 16 is a perspective view showing a state in which the piezoelectric resonator according to the second embodiment is mounted on a mounting substrate.
FIG. 17 is a diagram illustrating resonance characteristics in a state before the piezoelectric resonator according to the second embodiment is mounted on a mounting substrate.
FIG. 18 is a diagram illustrating resonance characteristics in a state after the piezoelectric resonator according to the second embodiment is mounted on a mounting substrate.
FIG. 19 is an exploded perspective view for explaining an application example as a filter component using two piezoelectric resonators.
FIG. 20 is a perspective view showing a piezoelectric resonator using a thickness-slip mode as a third embodiment of the composite material vibration device according to the invention.
FIG. 21 is a perspective view showing a state in which the piezoelectric resonator according to the third embodiment is mounted on a mounting board.
FIG. 22 is a diagram illustrating resonance characteristics in a state where the piezoelectric resonator according to the third embodiment is mounted on a mounting substrate;
FIG. 23 is a schematic cross-sectional view showing a piezoelectric resonator using thickness longitudinal vibration as a modification of the composite material vibration device of the present invention.
FIG. 24 is a schematic cross-sectional view for explaining a piezoelectric resonator using a laminated thickness longitudinal vibration mode as another modification of the composite material vibration device according to the invention.
FIGS. 25A to 25C are schematic cross-sectional views showing modifications of the piezoelectric resonator using a length mode configured according to the present invention. FIGS.
FIG. 26 is a diagram showing a displacement distribution analyzed by the element element method having a configuration in which a reflective layer is arranged in a direction orthogonal to a vibration propagation direction of a piezoelectric element using a length mode in the present invention.
FIGS. 27A and 27B are each a modified example of a piezoelectric resonator configured in accordance with the present invention, in which a reflective layer and a holding member are connected to both sides of a piezoelectric element utilizing thickness longitudinal vibration. FIGS. FIG.
FIG. 28 is a schematic cross-sectional view of a piezoelectric resonator having a piezoelectric element using a thickness torsion mode as a vibration member, which is a composite material vibration device configured according to the present invention.
FIG. 29 is a plan view showing a surface acoustic wave resonator as another modification of the composite material vibration device according to the invention.
30 (a) to 30 (c) are schematic cross-sectional views showing piezoelectric resonators using a thickness shear mode as a modification of the composite material vibration device according to the present invention.
FIGS. 31A to 31C are schematic block diagrams of a composite material vibration device according to the present invention, each showing a modification of the composite material vibration device having first and second vibration members. FIGS.
FIG. 32 is a schematic block diagram showing another example of the composite material vibration device according to the present invention having the first and second vibration members.
FIG. 33 is a schematic partially cutaway longitudinal sectional view for explaining a state in which a conventional energy confinement type piezoelectric resonator is mounted on a substrate.
FIG. 34 is a longitudinal sectional view showing an example of a conventional bulk acoustic wave filter.
[Explanation of symbols]
1. Piezoelectric resonator (composite material vibration device)
2 ... Piezoelectric element
3, 4 ... 1st and 2nd reflective layer
5, 6 ... first and second holding members
7, 8 ... Excitation electrode
9, 10 ... Terminal electrode
31. Piezoelectric resonator (composite material vibration device)
32. Piezoelectric element (composite material vibration device)
33, 34 ... first and second reflective layers
35, 36 ... first and second holding members
61 ... Piezoelectric resonator (composite material vibration device)
62: Piezoelectric element
65, 66 ... reflective layer
67, 68 ... holding member
81: Piezoelectric resonator
82: Piezoelectric element
85, 86 ... reflective layer
87, 88 ... Holding member
91: Piezoelectric resonator
92: Piezoelectric element
101-103 ... piezoelectric resonator
104: Piezoelectric element
105, 106 ... reflective layer
107, 108 ... holding member
111, 112 ... piezoelectric resonator
111a, 112a ... piezoelectric element
113: Piezoelectric resonator
113a ... Piezoelectric element
115, 116 ... reflective layer
117, 118 ... holding member
121 ... surface wave resonator
122 ... piezoelectric plate
125, 126 ... reflective layer
127, 128 ... holding member
151, 152 ... Vibration member
153: Reflective layer
154, 155 ... reflective layer
156, 157 ... Holding member
161. First vibration member
162, 163 ... first and second reflective layers
164,165 ... first and second holding members
166: Reflective layer
167 ... Vibration member
168 ... reflective layer
169 ... Holding member
171 ... Composite material vibration device
172, 173 ... Composite material vibration device
174 ... Reflective layer

Claims (12)

A composite vibration device in which a plurality of material portions having different acoustic impedances are combined,
A vibration member made of a material having a _first acoustic impedance value Z ₁ and serving as a vibration source;
First and second excitation electrodes formed on the vibrating member;
A first reflection layer made of a material having a _second acoustic impedance value Z ₂ and connected to both sides of the vibration member;
Made of a material having a third acoustic impedance Z _3, the first, and the first, second retaining member the vibration member of the second reflective layer which is connected to the side opposite to the side that is connected,
The first and second excitation electrodes formed on the vibration member are connected to the first and second excitation electrodes, respectively, and are formed so as to reach the first and second holding members through the surfaces of the first and second reflection layers, respectively. First and second terminal electrodes ,
Wherein a ratio second to the first acoustic impedance Z ₁ of the acoustic impedance Z ₂ Z ₂ / Z ₁ is 0.2 or less, and the second third acoustic impedance Z ₂ of the acoustic impedance Z ratio ₃ Z ₂ / Z ₃ is 0.2 or less,
A composite material vibration device configured to reflect vibration propagated from the vibration member to the reflection layer at an interface between the reflection layer and the holding member. The composite material vibration device according to claim 1, wherein the vibration member is an electromechanical coupling conversion element. The composite material vibration device according to claim 2 , wherein the electromechanical coupling conversion element is a piezoelectric element or an electrostrictive element. A third reflective layer, a second vibrating member, and a fourth reflective layer are provided on the opposite side of the first and / or second holding member to the side where the first and second reflective layers are connected. and third holding member are connected in this order, composite vibration device according to any one of claims 1 to 3. A composite material vibration device in which a plurality of material portions having different acoustic impedances are combined,
A first and second vibrating member made of a material having a _first acoustic impedance value Z ₁ and serving as a vibration source;
First and second excitation electrodes formed on the first and second vibrating members;
First to third reflective layers made of a material having a _second acoustic impedance value Z ₂ ;
First and second holding members made of a material having a _third acoustic impedance Z ₃ ,
The first holding member, the first reflecting layer, the first vibrating member, the second reflecting layer, the second vibrating member, the third reflecting layer, and the second holding member are connected in this order,
The first and second holding members are connected to first and second excitation electrodes formed on the first and second vibrating members, respectively, and pass through the surfaces of the first and third reflective layers, respectively. Further comprising first and second terminal electrodes formed to reach
Wherein a ratio second to the first acoustic impedance Z ₁ of the acoustic impedance Z ₂ Z ₂ / Z ₁ is 0.2 or less, and the second third acoustic impedance Z ₂ of the acoustic impedance Z ratio ₃ Z ₂ / Z ₃ is 0.2 or less,
Each vibration generated in the first and second vibrating members is caused by the interface between the first or third reflective layer and the first or second holding member, and the second vibration of the second reflective layer. A composite material vibration device reflected by an interface with a member or a first vibration member. The reflective layer is configured by stacking a plurality of material layers which acoustic impedance is different, composite vibration device according to any one of claims 1-5. When the wavelength of vibration when the vibrating member vibrates alone is λ, the distance from the interface between the reflective layer and the vibrating member to the interface between the reflective layer and the holding member is n · λ / 4 ± λ. / 8 (n is an odd number), characterized in that the range of the composite material vibration device according to any one of claims 1-6. The composite according to claim 3 , wherein directions A to C are parallel to each other, where A is a vibration displacement direction of the vibration member, B is a vibration propagation direction in the vibration member, and C is a vibration propagation direction in the reflection layer. Material vibration device. When the vibration displacement direction A of the vibration member, the vibration propagation direction B of the vibration member, and the vibration propagation direction of the reflection layer are C, the direction A and the direction B are parallel, and the direction B and the direction C are orthogonal. The composite material vibration device according to claim 3 , which is in a relationship. When the vibration displacement direction A of the vibration member, the vibration propagation direction B of the vibration member, and the vibration propagation direction C of the reflective layer are defined, the direction A and the direction B are orthogonal, and the direction B and the direction C are parallel. The composite material vibration device according to claim 3 . When the vibration displacement direction A of the vibration member, the vibration propagation direction B of the vibration member, and the vibration propagation direction C of the reflective layer are defined, the direction A and the direction B are orthogonal, and the direction B and the direction C are orthogonal. The composite material vibration device according to claim 3 , wherein A mounting board on which the composite material vibration device according to claim 1 is mounted is further provided, and the first and second terminal electrodes reaching the holding member are joined to the mounting board. The mounting structure of the composite material vibration device.

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