WO2016093228A1 - Vibrating body and vibrating body array - Google Patents

Vibrating body and vibrating body array Download PDF

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Publication number
WO2016093228A1
WO2016093228A1 PCT/JP2015/084396 JP2015084396W WO2016093228A1 WO 2016093228 A1 WO2016093228 A1 WO 2016093228A1 JP 2015084396 W JP2015084396 W JP 2015084396W WO 2016093228 A1 WO2016093228 A1 WO 2016093228A1
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support plate
acoustic matching
main surface
vibration
piezoelectric
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PCT/JP2015/084396
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French (fr)
Japanese (ja)
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雅史 齋藤
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株式会社村田製作所
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors

Definitions

  • the present invention relates to a vibrating body and a vibrating body array that transmit or receive ultrasonic waves.
  • Patent Document 1 Japanese Laid-Open Patent Publication No. 2002-186617 states that “a vibrating element array in which electrode elements are formed on both surfaces is arranged in a predetermined array structure and spaced from each other, and each of the vibration elements described above.
  • a common electrode that is connected to one electrode layer of the element and electrically connects each of the vibration elements, and is provided individually corresponding to each of the vibration elements, and is mounted on the common electrode with a space between each other
  • a two-dimensional ultrasonic probe comprising a separate acoustic matching layer.
  • Patent Document 2 JP-T-2004-512856 (Patent Document 2) describes a configuration in which a piezoelectric array element layer is provided on one side of an intermediate layer made of aluminum or the like, and an outer matching layer is provided on the other side. ing.
  • the entire array has a structure supported by an intermediate layer, and the intermediate layer is required to have good thermal conductivity and mechanical strength.
  • the edge of the intermediate layer is bonded to the metal case with a conductive adhesive.
  • An ultrasonic array sensor represented by a probe of an ultrasonic diagnostic apparatus includes a piezoelectric body, a matching layer provided on one main surface of the piezoelectric body, and a backing material provided on the other main surface of the piezoelectric body.
  • a piezoelectric body as a vibrator is supported by a backing material. It is difficult to support the vibrator by using an intermediate electrode provided between the piezoelectric body and the matching layer instead of the backing material, because vibration is attenuated as described later.
  • an object of the present invention is to provide a vibrating body and a vibrating body array in which attenuation of vibration due to holding is suppressed.
  • a vibrating body includes a support plate having a first main surface and a second main surface facing away from the first main surface, and the first main surface of the support plate. And a sound matching layer provided on the second main surface of the support plate so as to face the piezoelectric body, wherein a vibration node by the vibration body is provided.
  • the thickness of the acoustic matching layer and the thickness of the piezoelectric body are set so that the point is located on the support plate.
  • maintenance can be provided.
  • the thickness of the acoustic matching layer is a quarter of a wavelength when vibration propagates in the acoustic matching layer, and the thickness of the piezoelectric body is such that vibration propagates in the piezoelectric body. It is 70% of a quarter of the wavelength at the time.
  • the node point of vibration by the vibrating body can be easily positioned on the support plate.
  • the vibrator array according to the present invention is provided on the first main surface of the support plate, the support plate having a first main surface and a second main surface facing the opposite side of the first main surface, A plurality of piezoelectric bodies arranged along one main surface, and provided on the second main surface of the support plate so as to face each of the plurality of piezoelectric bodies on a one-to-one basis, A plurality of acoustic matching layers arranged along the one-to-one combination of the plurality of piezoelectric bodies and the plurality of acoustic matching layers at positions corresponding to each other across the support plate Is defined as a vibrating body, the thickness of the plurality of acoustic matching layers and the thickness of the plurality of piezoelectric bodies are set so that the node point of vibration by the vibrating body is located on the support plate.
  • each of the plurality of acoustic matching layers is a quarter of the wavelength when the longitudinal vibration propagates through the plurality of acoustic matching layers, and the thickness of each of the plurality of piezoelectric bodies is The longitudinal vibration is 70%, which is a quarter of the wavelength when propagating through the plurality of piezoelectric bodies.
  • the vibration node point by the vibrating body can be easily positioned on the support plate.
  • FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. It is a bottom view of the vibrating body array in Embodiment 3 based on this invention.
  • FIG. 1 is a cross-sectional view of the vibrating body 101.
  • the vibrating body 101 includes a support plate 1, a piezoelectric body 2, and an acoustic matching layer 3.
  • the support plate 1 is a conductor.
  • the support plate 1 is made of stainless steel having high elasticity and light weight, for example.
  • the support plate 1 has a flat plate shape, for example.
  • the thickness of the support plate is 0.2 mm, for example.
  • the support plate 1 has a first main surface 1a and a second main surface 1b facing away from the first main surface 1a.
  • the piezoelectric body 2 is provided on the first main surface 1 a of the support plate 1.
  • the piezoelectric body 2 is made of, for example, lead zirconate titanate ceramic.
  • the piezoelectric body 2 has, for example, a cubic shape with a length of 2.3 mm, a width of 2.3 mm, and a thickness of 2.3 mm.
  • An electrode 6 is formed on one main surface of the piezoelectric body 2 on the first main surface 1a side of the support plate 1, and an electrode 5 is formed on the other main surface facing away from the one main surface. Yes.
  • One main surface of the piezoelectric body 2 is joined to the first main surface 1a of the support plate 1 by a conductive adhesive. Thereby, the electrode 6 provided on the one main surface of the piezoelectric body 2 is electrically connected to the support plate 1.
  • the piezoelectric body 2 is joined to the first main surface 1a so that vibration can be transmitted to the support plate 1.
  • the acoustic matching layer 3 is provided on the second main surface 1 b of the support plate 1 at a position facing the piezoelectric body 2.
  • the acoustic matching layer 3 has, for example, a rectangular parallelepiped shape having a length of 2.3 mm, a width of 2.3 mm, and a thickness of 1.7 mm.
  • the acoustic matching layer 3 is made of a low specific gravity material in which, for example, an epoxy resin is mixed with a glass balloon.
  • the thickness direction of the support plate 1, that is, the vertical direction in FIG. 1 is defined as “thickness direction”.
  • One main surface which is a surface perpendicular to the thickness direction of the acoustic matching layer 3 is bonded to the second main surface 1b by an adhesive.
  • the acoustic matching layer 3 is bonded to the second main surface 1b so that vibration can be transmitted to the support plate 1.
  • the acoustic matching layer 3 is directly connected to the support plate 1.
  • Wiring is connected to the support plate 1 and the electrode 5 respectively.
  • the support plate 1 is electrically connected to the terminal 61.
  • the electrode 5 is electrically connected to the terminal 62.
  • Both ends of the support plate 1 included in the vibrating body 101 are fixed to a housing (not shown) made of, for example, aluminum.
  • the piezoelectric body 2 is supplied with AC voltage boosted by an amplifier circuit (not shown) as needed via terminals 61 and 62. Thereby, vibration is generated in the piezoelectric body 2.
  • the vibration is transmitted to the acoustic matching layer 3 through the support plate 1.
  • ultrasonic waves are transmitted (transmitted) from the acoustic matching layer 3 side of the vibrating body 101 toward the air.
  • vibration as used herein means a vibration whose main vibration is a longitudinal thickness vibration that alternately repeats a state extending and contracting in the thickness direction even when not explicitly described as “thickness longitudinal vibration”. The same applies to the following embodiments.
  • the vibrating body 101 is connected to a resistor and a capacitor (not shown). As indicated by an arrow 92 in FIG. 1, when the vibrating body 101 receives an ultrasonic wave, the piezoelectric body 2 vibrates together with the support plate 1, and the generated received signal has a voltage value via the terminals 61 and 62. Is sent to a receiving amplifier (not shown) and input to a microcomputer (not shown). By using the microcomputer, it is possible to grasp information regarding the presence or absence of foreign matter and double feeding.
  • the vibrating bodies are used as a set of two, for example, in a financial apparatus such as a bank note counter or a sorter.
  • the vibrator and vibrator array according to the present invention can be used for counting the number of banknotes. It can also be used to detect foreign matter such as a tape affixed to a bill.
  • the node point of vibration by the vibrating body 101 is located inside the support plate 1.
  • the thickness of the acoustic matching layer 3 and the thickness of the piezoelectric body 2 are set so that the node point of vibration by the vibrating body 101 is located on the support plate 1.
  • the frequency of vibration propagating through the acoustic matching layer 3 is, for example, 268 kHz
  • the frequency of vibration propagating through the piezoelectric body 2 is, for example, 380 kHz.
  • the thickness T1 of the piezoelectric element 2 is 70%, for example ⁇ 1/4.
  • the "70% lambda 1/4" is a value including the error of ⁇ 5%.
  • the thickness T2 of the acoustic matching layer 3 is, for example, lambda 2/4.
  • the following shows the simulation performed by the inventor. Two types of vibrator array models used in the simulation will be described.
  • the basic configuration of the first model is the same as the configuration described in the first embodiment, but differs from the first embodiment in the following points.
  • the first model is a model of a vibrator array in which two vibrators are combined. That is, in this vibrating body array, two piezoelectric bodies 2 and two acoustic matching layers 3 are provided for each support plate 1. If the wavelength at which vibration propagates through the acoustic matching layer 3 is ⁇ 2 , the thickness of the acoustic matching layer 3 is 1 ⁇ 4 of ⁇ 2 . If the wavelength at which vibration propagates inside the piezoelectric body 2 is ⁇ 1 , the thickness of the piezoelectric body 2 is 1 ⁇ 4 of ⁇ 1 . By setting the piezoelectric body 2 and the acoustic matching layer 3 to such thicknesses, it is possible to realize a vibrating body that maximizes the vibration efficiency. In addition, even when the thickness of the acoustic matching layer 3 is 1 ⁇ 4 of ⁇ 2 and the thickness of the piezoelectric body 2 is 1 ⁇ 2 of ⁇ 2 , a vibrating body having the maximum vibration efficiency is realized. can do.
  • the second model is a model of a vibrator array in which two vibrators are combined. That is, in this vibrating body array, two piezoelectric bodies 2 and two acoustic matching layers 3 are provided for each support plate 1. If the wavelength at which vibration propagates through the acoustic matching layer 3 is ⁇ 2 , the thickness of the acoustic matching layer 3 is 1 ⁇ 4 of ⁇ 2 . Assuming that the wavelength at which vibration propagates inside the piezoelectric body 2 is ⁇ 1 , the thickness of the piezoelectric body 2 is 70% that is 1 ⁇ 4 of ⁇ 1 .
  • the simulation result of the first model is shown in FIG. In FIG. 2, the magnitude of the displacement of each member due to the vibration of the vibrating body is indicated by a color change.
  • the displacement directions of the piezoelectric body 2 and the acoustic matching layer 3 are opposite to each other with the support plate 1 interposed therebetween.
  • the momentum mv of the piezoelectric body 2 is larger than the momentum of the acoustic matching layer 3, the node point 15 is located inside the piezoelectric body 2 in order to maintain a balance.
  • the word “point” is used for “node point”, but the node point is not limited to a single point geometrically, and may actually have a spread of a surface.
  • the support plate 1 vibrates, as can be seen from the fact that the color of the support plate 1 in FIG. More specifically, not only vibration is transmitted from the piezoelectric body 2 to the acoustic matching layer 3 via the support plate 1, but also vibration is transmitted to an external member (not shown) holding the support plate 1.
  • vibration leakage to the outside occurs.
  • the mass of the piezoelectric body 2 and the mass of the acoustic matching layer 3 are different by a factor of ten, so that the vibration node point of the support plate 1 is accidentally changed in the configuration of the first model. It is not located inside.
  • FIG. 3 The simulation results of the second model are shown in FIG. In FIG. 3, the magnitude of the displacement of each member due to the vibration of the vibrating body is indicated by a color change.
  • the thickness of the piezoelectric body 2 is smaller than that of the first model, the displacement of each member due to the vibration of the vibrating body 1 is reduced, and the momentum of the piezoelectric body 2 is also reduced. Since the momentum mv of the piezoelectric body 2 is almost equal to the momentum of the acoustic matching layer 3, the vibration node point 15 is positioned so as to overlap the support plate 1 as shown in FIG. 3.
  • the second model as can be seen from the fact that the color of the support plate 1 in FIG.
  • the amount of energy applied to the piezoelectric body 2 may be approximately the same as the energy of the ultrasonic wave sent out from the acoustic matching layer 3 along the arrow 91.
  • the vibrator array of the second model is expressed by a spring mass model relating to the momentum, and the displacement in the thickness direction of each part of the vibrator is measured by simulation, it is as shown in FIG.
  • the horizontal axis indicates the position in the thickness direction of each part included in the vibrator, and the vertical axis indicates the magnitude of the vibration displacement in the thickness direction at the part.
  • the lower end of the piezoelectric body 2 in FIG. 1 corresponds to part A in FIG. In this part, the vibration displacement is about ⁇ 2.5 nm.
  • the upper end of the acoustic matching layer 3 in FIG. 1 corresponds to part C in FIG. In this part, the vibration displacement is about +23 nm.
  • the support plate 1 in FIG. 1 corresponds to part B in FIG. In this part, the vibration displacement is almost zero. That is, in the second model, it can be seen that the support plate 1 is not displaced substantially even if the piezoelectric body 2 and the acoustic matching layer 3 vibrate longitudinally.
  • FIG. 5 is a graph showing impedance characteristics of the vibrating body in the present embodiment as a single vibrator.
  • 5 is a position at a frequency of 268 kHz, which is a resonance point of the acoustic matching layer 3.
  • 5 is a position at a frequency of 380 kHz, which is a resonance point of the piezoelectric body 2.
  • the node point of vibration by the vibrating body 101 is located inside the support plate 1. For this reason, when the vibrating body 101 is held, even if the support plate 1 is held by an external member, the energy hardly leaks to the outside through the support plate 1. Therefore, in the present embodiment, it is possible to realize a vibrating body that suppresses attenuation of vibration characteristics due to holding.
  • the thickness of the acoustic matching layer 3 is a quarter of the wavelength when vibration propagates inside the acoustic matching layer 3, and the thickness of the piezoelectric body 2 is such that vibration propagates inside the piezoelectric body 2. It is preferable that it is 70% of a quarter of the wavelength. “70% of a quarter of the wavelength” means 17.5% of the wavelength. Note that “70% of a quarter of the wavelength” is a value including an error of ⁇ 5%.
  • FIG. 6 A cross-sectional view of the vibrator array 201 in the present embodiment is shown in FIG. 6, and a plan view is shown in FIG.
  • the individual basic configurations of the vibrating bodies included in the vibrating body array in the present embodiment are the same as those described in the first embodiment, but differ in the following points from the first embodiment.
  • a plurality of piezoelectric bodies 2 and a plurality of acoustic matching layers 3 are provided for one support plate 1.
  • the vibrating body array 201 has a plurality of acoustic matching layers 3 arranged in a 2 ⁇ 3 matrix.
  • the plurality of piezoelectric bodies 2 are arranged so as to face the support plate 1 in a one-to-one correspondence with the plurality of acoustic matching layers 3 described above.
  • the plurality of piezoelectric bodies 2 are arranged close to each other with a gap 13 therebetween.
  • the acoustic matching layers 3 are arranged close to each other with a gap 14 therebetween.
  • wirings and terminals are not shown.
  • the node point of vibration by the vibrator array 201 is located inside the support plate 1.
  • the thicknesses of the plurality of piezoelectric bodies 2 with respect to the thicknesses of the plurality of acoustic matching layers 3 are set so that the node points of vibration by the vibrating body 101 are positioned on the support plate 1.
  • An example is shown below.
  • the frequency of vibration propagating through the acoustic matching layer 3 is, for example, 268 kHz
  • the frequency of vibration propagating through the piezoelectric body 2 is, for example, 380 kHz. If the wavelength at which vibration propagates through the piezoelectric body 2 is ⁇ 1 , the thickness of the plurality of piezoelectric bodies 2 is, for example, 1 ⁇ 4 of ⁇ 1 .
  • the thickness of the plurality of acoustic matching layers 3 is, for example, 70% of 1 ⁇ 4 of ⁇ 2 . Note that 70% of 1 ⁇ 4 of ⁇ 2 is a value including an error of ⁇ 5%.
  • the plurality of piezoelectric bodies 2 are all the same thickness. All of the plurality of acoustic matching layers 3 have the same thickness.
  • FIG. 7 shows an example in which a total of six acoustic matching layers 3 of 2 ⁇ 3 are arranged as a plurality of acoustic matching layers 3, the number and arrangement pattern of the plurality of acoustic matching layers 3 are here. It is not restricted to what was shown by.
  • transmission and reception of ultrasonic waves can be performed. That is, by applying a voltage between the support plate 1 and the electrode 5, the plurality of piezoelectric bodies 2 are deformed, and this vibration is transmitted to the plurality of acoustic matching layers 3 via the support plate 1, thereby As the matching layer 3 vibrates, ultrasonic waves are emitted to the outside. Transmission is thus performed.
  • the vibration body array is used instead of a single vibration body, ultrasonic waves can be emitted over a wide area.
  • the vibration characteristics of individual vibrators are averaged over the whole vibrator array, the influence of variations in the vibration characteristics of the individual vibrators can be reduced.
  • the thickness of the plurality of acoustic matching layers 3 is a quarter of the wavelength when vibration propagates through the plurality of acoustic matching layers 3, and the thickness of the plurality of piezoelectric bodies 2 is the thickness of the plurality of piezoelectric matching layers 3. It is preferably 70% of one quarter of the wavelength when propagating through the body 2. “70% of a quarter of the wavelength” means 17.5% of the wavelength. Note that “70% of a quarter of the wavelength” is a value including an error of ⁇ 5%.
  • FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG.
  • the surface on which the acoustic matching layer 3 is disposed is shown, but the surface on the opposite side is as shown in FIG.
  • a total of 24 acoustic matching layers 3 of 2 ⁇ 12 are produced from an integral plate material. That is, as shown in FIGS. 8 and 9, 24 acoustic matching layers 3 are cut by making cuts 9 in an integral plate. The notch 9 is left in a partially connected state without completely cutting the plate material. Therefore, the 24 acoustic matching layers 3 can be handled as an integral body without being dissipated, and are adhered to the support plate 1 with an adhesive as it is.
  • the block of 24 acoustic matching layers 3 has stepped portions 4 intermittently on the long side.
  • the stepped portion 4 is the surface of the acoustic matching layer 3 that is in contact with the one main surface, that is, acoustic. It is a convex portion protruding outward from the side surface of the matching layer 3.
  • the step portion 4 is formed integrally with the acoustic matching layer 3.
  • the surface on the one main surface side of the stepped portion 4 is a flat surface continuing from the one main surface of the acoustic matching layer 3.
  • the piezoelectric body 2 is also divided into 24 piezoelectric bodies 2 by making cuts 11 in an integral piezoelectric material plate as shown in FIGS.
  • the cut 11 is left in a partially connected state without completely cutting the piezoelectric material plate. Therefore, the 24 piezoelectric bodies 2 can be handled as an integral body without being dissipated, and are attached to the support plate 1 as an integral body.
  • the piezoelectric element is made of a lead zirconate titanate ceramic, but the material of the piezoelectric element is not limited to this.
  • it may be made of a lead-free piezoelectric ceramic piezoelectric material such as potassium sodium niobate or alkali niobate ceramic.
  • 1 support plate 1a 1st main surface, 1b 2nd main surface, 2 piezoelectric body, 3 acoustic matching layer, 5, 6 electrodes, 9, 11 notches, 13, 14 gap, 15 node points, 31 blocks, 61, 62 Terminal, 91, 92, 93, 94, 95 arrow, 101 vibrator, 201 vibrator array.

Abstract

A vibrating body (101) comprising: a support plate (1) which has a first main surface (1a) and a second main surface (1b) that faces the opposite side to the first main surface (1a); a piezoelectric body (2) which is provided to the first main surface (1a) of the support plate (1); and an acoustic matching layer (3) which is provided to the second main surface (1b) of the support plate (1) in a manner so as to oppose the piezoelectric body (2). The thickness of the acoustic matching layer (3) and the thickness of the piezoelectric body (2) are set in a manner such that node points of vibration by this vibrating body are located in the support plate (1).

Description

振動体および振動体アレイVibrating body and vibrating body array
　本発明は、超音波を送信または受信する振動体および振動体アレイに関するものである。 The present invention relates to a vibrating body and a vibrating body array that transmit or receive ultrasonic waves.
　特開２００２－１８６６１７号公報（特許文献１）には、「両面に電極層が形成された振動素子が所定のアレイ構造に従い相互に間隔をあけて配列構成された振動素子アレイと、前記各振動素子の一方の電極層に接続され、それら各振動素子を電気的に接続する共通電極と、前記各振動素子に対応してそれぞれ個別に設けられ、相互に間隔をあけて前記共通電極上に取り付けられた個別音響整合層と、を備える２次元超音波探触子」が記載されている。 Japanese Laid-Open Patent Publication No. 2002-186617 (Patent Document 1) states that “a vibrating element array in which electrode elements are formed on both surfaces is arranged in a predetermined array structure and spaced from each other, and each of the vibration elements described above. A common electrode that is connected to one electrode layer of the element and electrically connects each of the vibration elements, and is provided individually corresponding to each of the vibration elements, and is mounted on the common electrode with a space between each other A two-dimensional ultrasonic probe comprising a separate acoustic matching layer.
　特表２００４－５１２８５６号公報（特許文献２）には、アルミニウムなどからなる中間層の一方の側に圧電アレイ要素層が設けられ、他方の側には外側整合層が設けられた構成が記載されている。特許文献２に記載された構成では、アレイ全体は、中間層で支える構造となっており、中間層には良好な熱伝導性および機械的強度が求められている。中間層の縁は導電性の接着剤で金属ケースに結合されている。 JP-T-2004-512856 (Patent Document 2) describes a configuration in which a piezoelectric array element layer is provided on one side of an intermediate layer made of aluminum or the like, and an outer matching layer is provided on the other side. ing. In the configuration described in Patent Document 2, the entire array has a structure supported by an intermediate layer, and the intermediate layer is required to have good thermal conductivity and mechanical strength. The edge of the intermediate layer is bonded to the metal case with a conductive adhesive.
特開２００２－１８６６１７号公報JP 2002-186617 A 特表２００４－５１２８５６号公報Special table 2004-512856 gazette
　超音波診断装置のプローブに代表されるような超音波アレイセンサは、圧電体と、圧電体の一方主面に設けられた整合層と、圧電体の他方主面に設けられたバッキング材とを備える。振動子である圧電体は、バッキング材によって支持されていることが一般的である。バッキング材の代わりに圧電体と整合層との間に設けられた中間電極を以て振動子を支持することは、後述するように、振動の減衰をもたらすので、困難であった。 An ultrasonic array sensor represented by a probe of an ultrasonic diagnostic apparatus includes a piezoelectric body, a matching layer provided on one main surface of the piezoelectric body, and a backing material provided on the other main surface of the piezoelectric body. Prepare. In general, a piezoelectric body as a vibrator is supported by a backing material. It is difficult to support the vibrator by using an intermediate electrode provided between the piezoelectric body and the matching layer instead of the backing material, because vibration is attenuated as described later.
　特許文献１，２に記載されたアレイ構造では、圧電体を利用した振動素子から発生した縦振動が、共通電極、中間層などを通じて整合層へと伝わってさらに整合層から外部に送信される。これらのアレイ構造は、共通電極、中間層などによって支持されている。しかし、このような支持のための部材自体も本来は振動をしているものなので、これを固定して保持することによって振動が大きく減衰してしまうという問題があった。また、支持のための部材から外部に振動が漏れ伝わることによって、他の箇所で不具合をきたす可能性もあった。 In the array structures described in Patent Documents 1 and 2, longitudinal vibration generated from a vibration element using a piezoelectric body is transmitted to a matching layer through a common electrode, an intermediate layer, and the like, and further transmitted from the matching layer to the outside. These array structures are supported by a common electrode, an intermediate layer, and the like. However, since the supporting member itself vibrates originally, there is a problem that vibration is greatly attenuated by fixing and holding the member. In addition, there is a possibility of causing problems at other locations due to vibrations leaking from the supporting member to the outside.
　そこで、本発明は、保持による振動の減衰を抑えた振動体および振動体アレイを提供することを目的とする。 Therefore, an object of the present invention is to provide a vibrating body and a vibrating body array in which attenuation of vibration due to holding is suppressed.
　上記目的を達成するため、本発明に基づく振動体は、第１主面および上記第１主面とは反対側を向く第２主面を有する支持板と、上記支持板の上記第１主面に設けられている圧電体と、上記圧電体と対向するように上記支持板の上記第２主面に設けられている音響整合層とを備える振動体であって、上記振動体による振動のノード点が上記支持板に位置するように、上記音響整合層の厚みおよび上記圧電体の厚みが設定されている。 In order to achieve the above object, a vibrating body according to the present invention includes a support plate having a first main surface and a second main surface facing away from the first main surface, and the first main surface of the support plate. And a sound matching layer provided on the second main surface of the support plate so as to face the piezoelectric body, wherein a vibration node by the vibration body is provided. The thickness of the acoustic matching layer and the thickness of the piezoelectric body are set so that the point is located on the support plate.
　本発明によれば、保持による振動の減衰を抑えた振動体を提供することができる。
　好ましくは、上記音響整合層の厚みは、振動が上記音響整合層の中を伝播するときの波長の４分の１であり、上記圧電体の厚みは、振動が上記圧電体の中を伝播するときの波長の４分の１の７０％である。 ADVANTAGE OF THE INVENTION According to this invention, the vibrating body which suppressed attenuation | damping of the vibration by holding | maintenance can be provided.
Preferably, the thickness of the acoustic matching layer is a quarter of a wavelength when vibration propagates in the acoustic matching layer, and the thickness of the piezoelectric body is such that vibration propagates in the piezoelectric body. It is 70% of a quarter of the wavelength at the time.
　圧電体の厚みおよび音響整合層の厚みが上述の関係を満たすことにより、振動体による振動のノード点を容易に支持板に位置させることができる。 When the thickness of the piezoelectric body and the thickness of the acoustic matching layer satisfy the above relationship, the node point of vibration by the vibrating body can be easily positioned on the support plate.
　本発明に基づく振動体アレイは、第１主面および上記第１主面とは反対側を向く第２主面を有する支持板と、上記支持板の上記第１主面に設けられ、上記第１主面に沿って配列されている複数の圧電体と、上記複数の圧電体とそれぞれ１対１で対向するように上記支持板の上記第２主面に設けられ、上記第２主面に沿って配列されている複数の音響整合層とを備え、上記複数の圧電体と上記複数の音響整合層とのうち上記支持板を挟んで互いに対応する位置にあるもの同士の１対１の組合せをそれぞれ振動体と定義したとき、上記振動体による振動のノード点が上記支持板に位置するように、上記複数の音響整合層の厚みおよび上記複数の圧電体の厚みが設定されている。 The vibrator array according to the present invention is provided on the first main surface of the support plate, the support plate having a first main surface and a second main surface facing the opposite side of the first main surface, A plurality of piezoelectric bodies arranged along one main surface, and provided on the second main surface of the support plate so as to face each of the plurality of piezoelectric bodies on a one-to-one basis, A plurality of acoustic matching layers arranged along the one-to-one combination of the plurality of piezoelectric bodies and the plurality of acoustic matching layers at positions corresponding to each other across the support plate Is defined as a vibrating body, the thickness of the plurality of acoustic matching layers and the thickness of the plurality of piezoelectric bodies are set so that the node point of vibration by the vibrating body is located on the support plate.
　本発明によれば、保持による振動の減衰を抑えた振動体アレイを提供することができる。 According to the present invention, it is possible to provide a vibrating body array in which vibration attenuation due to holding is suppressed.
　上記複数の音響整合層の各々の厚みは、上記縦振動が上記複数の音響整合層の中を伝播するときの波長の４分の１であり、上記複数の圧電体の各々の厚みは、上記縦振動が上記複数の圧電体の中を伝播するときの波長の４分の１の７０％である。 The thickness of each of the plurality of acoustic matching layers is a quarter of the wavelength when the longitudinal vibration propagates through the plurality of acoustic matching layers, and the thickness of each of the plurality of piezoelectric bodies is The longitudinal vibration is 70%, which is a quarter of the wavelength when propagating through the plurality of piezoelectric bodies.
　複数の圧電体の厚みおよび複数の音響整合層の厚みが上述の関係を満たすことにより、振動体による振動のノード点を容易に支持板に位置させることができる。 When the thicknesses of the plurality of piezoelectric bodies and the thicknesses of the plurality of acoustic matching layers satisfy the above-described relationship, the vibration node point by the vibrating body can be easily positioned on the support plate.
　本発明によれば、保持による振動の減衰を抑えた振動体を提供することができる。 According to the present invention, it is possible to provide a vibrating body that suppresses vibration attenuation due to holding.
本発明に基づく実施の形態１における振動体の断面図である。It is sectional drawing of the vibrating body in Embodiment 1 based on this invention. 振動体アレイの第１のモデルにおけるシミュレーション結果を示す図である。It is a figure which shows the simulation result in the 1st model of a vibrating body array. 振動体アレイの第２のモデルにおけるシミュレーション結果を示す図である。It is a figure which shows the simulation result in the 2nd model of a vibrating body array. 振動体アレイの第２のモデルにおける振動体の各部位の厚み方向の変位を示すグラフである。It is a graph which shows the displacement of the thickness direction of each site | part of a vibrating body in the 2nd model of a vibrating body array. 本発明に基づく実施の形態１における振動体を１つの振動子とみなしたときのインピーダンス特性を示すグラフである。It is a graph which shows an impedance characteristic when the vibrating body in Embodiment 1 based on this invention is considered as one vibrator | oscillator. 本発明に基づく実施の形態２における振動体アレイの断面図である。It is sectional drawing of the vibrating body array in Embodiment 2 based on this invention. 本発明に基づく実施の形態２における振動体アレイの平面図である。It is a top view of the vibrating body array in Embodiment 2 based on this invention. 本発明に基づく実施の形態３における振動体アレイの平面図である。It is a top view of the vibrating body array in Embodiment 3 based on this invention. 図８におけるＩＸ－ＩＸ線に関する矢視断面図である。FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. 本発明に基づく実施の形態３における振動体アレイの下面図である。It is a bottom view of the vibrating body array in Embodiment 3 based on this invention.
　本発明に基づいた実施の形態について、個数および量などに言及する場合、特に記載がある場合を除き、本発明の範囲は必ずしもその個数および量などに限定されない。同一の部品および相当部品には同一の参照番号を付す。重複する説明は繰り返さない場合がある。 When referring to the number and amount of the embodiment based on the present invention, the scope of the present invention is not necessarily limited to the number and amount unless otherwise specified. The same reference numerals are assigned to the same parts and corresponding parts. Duplicate explanations may not be repeated.
　（実施の形態１）
　図１を参照して、本発明に基づく実施の形態１における振動体１０１について説明する。図１は、振動体１０１の断面図である。振動体１０１は、支持板１と、圧電体２と、音響整合層３とを備える。 (Embodiment 1)
With reference to FIG. 1, a vibrating body 101 according to the first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of the vibrating body 101. The vibrating body 101 includes a support plate 1, a piezoelectric body 2, and an acoustic matching layer 3.
　支持板１は、導電体である。支持板１は、たとえば、高い弾性を有しかつ軽量なステンレスからなる。支持板１は、たとえば平板状である。支持板の厚みはたとえば０．２ｍｍである。支持板１は、第１主面１ａと、第１主面１ａとは反対側を向く第２主面１ｂとを有する。 The support plate 1 is a conductor. The support plate 1 is made of stainless steel having high elasticity and light weight, for example. The support plate 1 has a flat plate shape, for example. The thickness of the support plate is 0.2 mm, for example. The support plate 1 has a first main surface 1a and a second main surface 1b facing away from the first main surface 1a.
　圧電体２は、支持板１の第１主面１ａ上に設けられている。圧電体２は、たとえばチタン酸ジルコン酸鉛系セラミックスからなる。圧電体２は、たとえば長さ２．３ｍｍ×幅２．３ｍｍ×厚み２．３ｍｍの立方体形状である。圧電体２における支持板１の第１主面１ａ側の一方主面には電極６が形成されており、当該一方主面とは反対側を向く他方主面には、電極５が形成されている。圧電体２の一方主面は、導電性接着剤によって支持板１の第１主面１ａに接合されている。これにより、圧電体２の一方主面に設けられた電極６は、支持板１と電気的に接続されている。また、圧電体２は、支持板１との間で振動を伝達可能なように第１主面１ａに接合されている。 The piezoelectric body 2 is provided on the first main surface 1 a of the support plate 1. The piezoelectric body 2 is made of, for example, lead zirconate titanate ceramic. The piezoelectric body 2 has, for example, a cubic shape with a length of 2.3 mm, a width of 2.3 mm, and a thickness of 2.3 mm. An electrode 6 is formed on one main surface of the piezoelectric body 2 on the first main surface 1a side of the support plate 1, and an electrode 5 is formed on the other main surface facing away from the one main surface. Yes. One main surface of the piezoelectric body 2 is joined to the first main surface 1a of the support plate 1 by a conductive adhesive. Thereby, the electrode 6 provided on the one main surface of the piezoelectric body 2 is electrically connected to the support plate 1. The piezoelectric body 2 is joined to the first main surface 1a so that vibration can be transmitted to the support plate 1.
　音響整合層３は、支持板１における第２主面１ｂ上であって、圧電体２と対向する位置に設けられている。音響整合層３は、たとえば長さ２．３ｍｍ×幅２．３ｍｍ×厚み１．７ｍｍの直方体形状である。音響整合層３は、たとえばエポキシ樹脂にガラスバルーンを混合させた低比重材料からなる。以下、支持板１以外のものに言及する際にも、支持板１の厚み方向、すなわち図１における上下方向を「厚み方向」と定義する。音響整合層３の厚み方向に垂直な面である一方主面は、接着剤によって第２主面１ｂに接合されている。また、音響整合層３は、支持板１との間で振動を伝達可能なように第２主面１ｂに接合されている。音響整合層３は、支持板１に直接接続されている。 The acoustic matching layer 3 is provided on the second main surface 1 b of the support plate 1 at a position facing the piezoelectric body 2. The acoustic matching layer 3 has, for example, a rectangular parallelepiped shape having a length of 2.3 mm, a width of 2.3 mm, and a thickness of 1.7 mm. The acoustic matching layer 3 is made of a low specific gravity material in which, for example, an epoxy resin is mixed with a glass balloon. Hereinafter, when referring to things other than the support plate 1, the thickness direction of the support plate 1, that is, the vertical direction in FIG. 1 is defined as “thickness direction”. One main surface which is a surface perpendicular to the thickness direction of the acoustic matching layer 3 is bonded to the second main surface 1b by an adhesive. The acoustic matching layer 3 is bonded to the second main surface 1b so that vibration can be transmitted to the support plate 1. The acoustic matching layer 3 is directly connected to the support plate 1.
　支持板１と電極５とにはそれぞれ配線が接続されている。支持板１は端子６１と電気的に接続されている。一方、電極５は端子６２と電気的に接続されている。 Wiring is connected to the support plate 1 and the electrode 5 respectively. The support plate 1 is electrically connected to the terminal 61. On the other hand, the electrode 5 is electrically connected to the terminal 62.
　振動体１０１に含まれる支持板１の両端は、たとえばアルミニウムからなる筐体（図示せず）に固定されている。 Both ends of the support plate 1 included in the vibrating body 101 are fixed to a housing (not shown) made of, for example, aluminum.
　振動体１０１を送信用途に用いる場合について説明する。圧電体２には、必要に応じて増幅回路（図示せず）により昇圧された交流電圧が端子６１，６２を介して供給される。これにより、圧電体２では振動が発生する。振動は、支持板１を介して音響整合層３へと伝わる。図１において矢印９１で示すように、振動体１０１における音響整合層３側から気中などに向けて超音波が送信（送波）される。ここでいう「振動」は、「厚み縦振動」と明記していない場合であっても、厚み方向に伸びる状態と縮む状態とを交互に繰り返す厚み縦振動を主振動とする振動を意味する。以下の実施の形態においても同様である。 The case where the vibrating body 101 is used for transmission will be described. The piezoelectric body 2 is supplied with AC voltage boosted by an amplifier circuit (not shown) as needed via terminals 61 and 62. Thereby, vibration is generated in the piezoelectric body 2. The vibration is transmitted to the acoustic matching layer 3 through the support plate 1. As indicated by an arrow 91 in FIG. 1, ultrasonic waves are transmitted (transmitted) from the acoustic matching layer 3 side of the vibrating body 101 toward the air. The term “vibration” as used herein means a vibration whose main vibration is a longitudinal thickness vibration that alternately repeats a state extending and contracting in the thickness direction even when not explicitly described as “thickness longitudinal vibration”. The same applies to the following embodiments.
　振動体１０１を受信用途に用いる場合について説明する。振動体１０１には、図示しない抵抗およびコンデンサなどが接続されている。図１において矢印９２で示すように、振動体１０１が超音波を受信した際には、圧電体２は、支持板１とともに振動し、発生した受波信号が端子６１，６２を介して電圧値として受信アンプ（図示せず）に送られ、マイコン（図示せず）に入力される。マイコンにより、異物の有無や重送に関する情報を把握することが可能となる。振動体は、２個１組としてたとえばバンクノートカウンター、ソーターなどの金融機器に用いられる。本発明に基づく振動体及び振動体アレイは、紙幣の枚数のカウントに用いることができる。また、紙幣に貼られたテープなどの異物の検知にも用いることができる。 A case where the vibrating body 101 is used for reception will be described. The vibrating body 101 is connected to a resistor and a capacitor (not shown). As indicated by an arrow 92 in FIG. 1, when the vibrating body 101 receives an ultrasonic wave, the piezoelectric body 2 vibrates together with the support plate 1, and the generated received signal has a voltage value via the terminals 61 and 62. Is sent to a receiving amplifier (not shown) and input to a microcomputer (not shown). By using the microcomputer, it is possible to grasp information regarding the presence or absence of foreign matter and double feeding. The vibrating bodies are used as a set of two, for example, in a financial apparatus such as a bank note counter or a sorter. The vibrator and vibrator array according to the present invention can be used for counting the number of banknotes. It can also be used to detect foreign matter such as a tape affixed to a bill.
　振動体１０１による振動のノード点は、支持板１の内部に位置している。具体的には、振動体１０１による振動のノード点が支持板１に位置するように、音響整合層３の厚みおよび圧電体２の厚みが設定されている。以下に一例を示す。音響整合層３の内部を伝播する振動の周波数は、たとえば２６８ｋＨｚであり、圧電体２の内部を伝播する振動の周波数は、たとえば３８０ｋＨｚである。振動が圧電体２の内部を伝播するときの波長をλ1とすると、圧電体２の厚みＴ１は、たとえばλ1／４の７０％である。なお、ここでいう「λ1／４の７０％」とは、±５％の誤差を含む値である。振動が音響整合層３の中を伝播するときの波長をλ2とすると、音響整合層３の厚みＴ２は、たとえばλ2／４である。 The node point of vibration by the vibrating body 101 is located inside the support plate 1. Specifically, the thickness of the acoustic matching layer 3 and the thickness of the piezoelectric body 2 are set so that the node point of vibration by the vibrating body 101 is located on the support plate 1. An example is shown below. The frequency of vibration propagating through the acoustic matching layer 3 is, for example, 268 kHz, and the frequency of vibration propagating through the piezoelectric body 2 is, for example, 380 kHz. When vibration is the wavelength lambda 1 when propagating inside the piezoelectric body 2, the thickness T1 of the piezoelectric element 2 is 70%, for example λ 1/4. Here, the "70% lambda 1/4" is a value including the error of ± 5%. When vibration is 2 wavelength lambda when propagating through the acoustic matching layer 3, the thickness T2 of the acoustic matching layer 3 is, for example, lambda 2/4.
　以下に発明者が行なったシミュレーションについて示す。シミュレーションで用いた２通りの振動体アレイのモデルについて説明する。第１のモデルの基本的な構成は、実施の形態１で説明した構成と同様であるが、実施の形態１に比べて以下の点で異なる。 The following shows the simulation performed by the inventor. Two types of vibrator array models used in the simulation will be described. The basic configuration of the first model is the same as the configuration described in the first embodiment, but differs from the first embodiment in the following points.
　第１のモデルは、振動体を２つ組み合わせた振動体アレイのモデルである。すなわち、この振動体アレイにおいては、１枚の支持板１に対して、圧電体２と、音響整合層３とがそれぞれ２つずつ設けられている。振動が音響整合層３の内部を伝播するときの波長をλ2とすると、音響整合層３の厚みはλ2の４分の１である。振動が圧電体２の内部を伝播するときの波長をλ1とすると、圧電体２の厚みはλ1の４分の１である。圧電体２と音響整合層３とをこのような厚みにすることで、振動効率が最大となる振動体を実現することができる。なお、音響整合層３の厚みをλ2の４分の１、圧電体２の厚みをλ2の２分の１とした場合であっても、同様に振動効率が最大となる振動体を実現することができる。 The first model is a model of a vibrator array in which two vibrators are combined. That is, in this vibrating body array, two piezoelectric bodies 2 and two acoustic matching layers 3 are provided for each support plate 1. If the wavelength at which vibration propagates through the acoustic matching layer 3 is λ 2 , the thickness of the acoustic matching layer 3 is ¼ of λ 2 . If the wavelength at which vibration propagates inside the piezoelectric body 2 is λ 1 , the thickness of the piezoelectric body 2 is ¼ of λ 1 . By setting the piezoelectric body 2 and the acoustic matching layer 3 to such thicknesses, it is possible to realize a vibrating body that maximizes the vibration efficiency. In addition, even when the thickness of the acoustic matching layer 3 is ¼ of λ 2 and the thickness of the piezoelectric body 2 is ½ of λ 2 , a vibrating body having the maximum vibration efficiency is realized. can do.
　第２のモデルは、振動体を２つ組み合わせた振動体アレイのモデルである。すなわち、この振動体アレイにおいては、１つの支持板１に対して、圧電体２と、音響整合層３とがそれぞれ２つずつ設けられている。振動が音響整合層３の内部を伝播するときの波長をλ2とすると、音響整合層３の厚みはλ2の４分の１である。振動が圧電体２の内部を伝播するときの波長をλ1とすると、圧電体２の厚みはλ1の４分の１の７０％である。 The second model is a model of a vibrator array in which two vibrators are combined. That is, in this vibrating body array, two piezoelectric bodies 2 and two acoustic matching layers 3 are provided for each support plate 1. If the wavelength at which vibration propagates through the acoustic matching layer 3 is λ 2 , the thickness of the acoustic matching layer 3 is ¼ of λ 2 . Assuming that the wavelength at which vibration propagates inside the piezoelectric body 2 is λ 1 , the thickness of the piezoelectric body 2 is 70% that is ¼ of λ 1 .
　これらのモデルを振動させ、各部材の変位の大きさを、シミュレーションにて測定した。モデル以外のシミュレーションの条件は同一である。 These models were vibrated, and the magnitude of displacement of each member was measured by simulation. The simulation conditions other than the model are the same.
　第１のモデルのシミュレーション結果を図２に示す。図２では、振動体の振動による各部材の変位の大きさを色の変化で示している。振動の際には、圧電体２および音響整合層３の変位の向きは支持板１を挟んで反対向きとなる。この場合、圧電体２の運動量ｍｖは音響整合層３の運動量に比べて大きくなるので、均衡を保つために、ノード点１５は圧電体２の内部に位置するようになる。ここで「ノード点」には「点」という語が用いられているが、幾何学的にはノード点は１点には限らず、実際には面の広がりを有するものであってよい。したがって、「ノード面」と呼んでもよいが、ここでは、慣習的にノード点と呼んでいる。第１のモデルでは、図２の支持板１の色に濃淡が見られることからもわかるように、支持板１が振動をしている。詳述すると、圧電体２から支持板１を介して音響整合層３に振動が伝わるだけでなく、支持板１を保持している外部の部材（図示せず）にも振動は伝わっている。このように、第１のモデルでは、たとえ圧電体２と音響整合層３との間に設けた支持板１によって振動体を支持したとしても、外部への振動漏れが発生してしまう。 The simulation result of the first model is shown in FIG. In FIG. 2, the magnitude of the displacement of each member due to the vibration of the vibrating body is indicated by a color change. During vibration, the displacement directions of the piezoelectric body 2 and the acoustic matching layer 3 are opposite to each other with the support plate 1 interposed therebetween. In this case, since the momentum mv of the piezoelectric body 2 is larger than the momentum of the acoustic matching layer 3, the node point 15 is located inside the piezoelectric body 2 in order to maintain a balance. Here, the word “point” is used for “node point”, but the node point is not limited to a single point geometrically, and may actually have a spread of a surface. Therefore, it may be called a “node plane”, but here it is conventionally called a node point. In the first model, the support plate 1 vibrates, as can be seen from the fact that the color of the support plate 1 in FIG. More specifically, not only vibration is transmitted from the piezoelectric body 2 to the acoustic matching layer 3 via the support plate 1, but also vibration is transmitted to an external member (not shown) holding the support plate 1. Thus, in the first model, even if the vibrating body is supported by the support plate 1 provided between the piezoelectric body 2 and the acoustic matching layer 3, vibration leakage to the outside occurs.
　第１のモデルの場合、図２において矢印９４で示すように、支持板１を通じて一部のエネルギーが外部に漏れてしまう。そこで、圧電体２には、矢印９３で示すように、音響整合層３から矢印９１に沿って外部に送り出される超音波のエネルギーよりも大きなエネルギーを与える必要があった。 In the case of the first model, as shown by an arrow 94 in FIG. 2, some energy leaks to the outside through the support plate 1. Therefore, it is necessary to give the piezoelectric body 2 energy larger than the energy of the ultrasonic wave sent out from the acoustic matching layer 3 along the arrow 91 as indicated by the arrow 93.
　なお、第１のモデルにおいて、圧電体２の質量と音響整合層３の質量とは十数倍の差があるために、第１のモデルの構成で偶然によって振動のノード点が支持板１の内部に位置することはない。 Note that in the first model, the mass of the piezoelectric body 2 and the mass of the acoustic matching layer 3 are different by a factor of ten, so that the vibration node point of the support plate 1 is accidentally changed in the configuration of the first model. It is not located inside.
　第２のモデルのシミュレーション結果を図３に示す。図３では、振動体の振動による各部材の変位の大きさを色の変化で示している。この場合、圧電体２の厚みが第１のモデルの場合よりも小さくなったことにより、振動体１の振動による各部材の変位が小さくなり、圧電体２の運動量も減少する。圧電体２の運動量ｍｖが音響整合層３の運動量とほとんど等しいので、図３に示すように、振動体の振動のノード点１５は支持板１に重なるように位置する。第２のモデルでは、図３の支持板１の色に濃淡が見られないことからもわかるように、支持板１はほぼ振動していない。 The simulation results of the second model are shown in FIG. In FIG. 3, the magnitude of the displacement of each member due to the vibration of the vibrating body is indicated by a color change. In this case, since the thickness of the piezoelectric body 2 is smaller than that of the first model, the displacement of each member due to the vibration of the vibrating body 1 is reduced, and the momentum of the piezoelectric body 2 is also reduced. Since the momentum mv of the piezoelectric body 2 is almost equal to the momentum of the acoustic matching layer 3, the vibration node point 15 is positioned so as to overlap the support plate 1 as shown in FIG. 3. In the second model, as can be seen from the fact that the color of the support plate 1 in FIG.
　第２のモデルの場合、図３に示すように、支持板１を通じてエネルギーが外部に漏れることがほぼない。したがって、図３に矢印９５で示すように、圧電体２に与えるエネルギーの量は、音響整合層３から矢印９１に沿って外部に送り出される超音波のエネルギーと同程度でよい。 In the case of the second model, as shown in FIG. 3, energy hardly leaks outside through the support plate 1. Therefore, as indicated by an arrow 95 in FIG. 3, the amount of energy applied to the piezoelectric body 2 may be approximately the same as the energy of the ultrasonic wave sent out from the acoustic matching layer 3 along the arrow 91.
　第２のモデルの振動体アレイを運動量に関するバネマスモデルで表現し、この振動体の各部位の厚み方向の変位をシミュレーションにより測定すると、図４に示すようになる。横軸は振動体に含まれる各部位の厚み方向の位置、縦軸は当該部位における厚み方向の振動変位の大きさを示す。図１における圧電体２の下端は、図４ではＡ部に相当する。この部位では振動変位は約－２．５ｎｍとなっている。図１における音響整合層３の上端は、図４ではＣ部に相当する。この部位では振動変位は約＋２３ｎｍとなっている。図１における支持板１は、図４ではＢ部に相当する。この部位では振動変位はほぼ０である。すなわち、第２のモデルでは、圧電体２と音響整合層３とが縦振動をしても支持板１はほぼ変位しないということがわかる。 When the vibrator array of the second model is expressed by a spring mass model relating to the momentum, and the displacement in the thickness direction of each part of the vibrator is measured by simulation, it is as shown in FIG. The horizontal axis indicates the position in the thickness direction of each part included in the vibrator, and the vertical axis indicates the magnitude of the vibration displacement in the thickness direction at the part. The lower end of the piezoelectric body 2 in FIG. 1 corresponds to part A in FIG. In this part, the vibration displacement is about −2.5 nm. The upper end of the acoustic matching layer 3 in FIG. 1 corresponds to part C in FIG. In this part, the vibration displacement is about +23 nm. The support plate 1 in FIG. 1 corresponds to part B in FIG. In this part, the vibration displacement is almost zero. That is, in the second model, it can be seen that the support plate 1 is not displaced substantially even if the piezoelectric body 2 and the acoustic matching layer 3 vibrate longitudinally.
　本実施の形態における振動体を１つの振動子とみなし、そのインピーダンス特性をグラフにすると図５に示すようになる。図５におけるＤ部は、周波数２６８ｋＨｚの位置であり、ここが音響整合層３の共振点である。図５におけるＥ部は、周波数３８０ｋＨｚの位置であり、ここが圧電体２の共振点である。 FIG. 5 is a graph showing impedance characteristics of the vibrating body in the present embodiment as a single vibrator. 5 is a position at a frequency of 268 kHz, which is a resonance point of the acoustic matching layer 3. 5 is a position at a frequency of 380 kHz, which is a resonance point of the piezoelectric body 2.
　本実施の形態では、振動体１０１による振動のノード点は、支持板１の内部に位置している。このため、振動体１０１を保持する際に、支持板１を外部の部材を以て保持しても支持板１を通じてエネルギーが外部へ漏れることがほぼない。したがって、本実施の形態では、保持による振動特性の減衰を抑えた振動体を実現することができる。 In this embodiment, the node point of vibration by the vibrating body 101 is located inside the support plate 1. For this reason, when the vibrating body 101 is held, even if the support plate 1 is held by an external member, the energy hardly leaks to the outside through the support plate 1. Therefore, in the present embodiment, it is possible to realize a vibrating body that suppresses attenuation of vibration characteristics due to holding.
　ここでは、圧電体２に電圧を印加して振動させ、音響整合層３から超音波を送信する場合について説明したが、音響整合層３から超音波を受信して圧電体２において電気信号に変換する場合にも同様であり、保持による振動特性の減衰を抑えた振動体を実現することができる。 Here, the case where a voltage is applied to the piezoelectric body 2 to vibrate and ultrasonic waves are transmitted from the acoustic matching layer 3 has been described. However, ultrasonic waves are received from the acoustic matching layer 3 and converted into electrical signals in the piezoelectric body 2. The same applies to the case where a vibration body that suppresses attenuation of vibration characteristics due to holding can be realized.
　なお、音響整合層３の厚みは、振動が音響整合層３の内部を伝播するときの波長の４分の１であり、かつ、圧電体２の厚みは、振動が圧電体２の内部を伝播するときの波長の４分の１の７０％であることが好ましい。「波長の４分の１の７０％」とは、波長の１７．５％である。なお、「波長の４分の１の７０％」といった場合は、±５％の誤差を含む値である。圧電体２の厚みおよび音響整合層３の厚みが上述の関係を満たすことにより、振動体１０１による振動のノード点を容易に支持板１に位置させることができる。 The thickness of the acoustic matching layer 3 is a quarter of the wavelength when vibration propagates inside the acoustic matching layer 3, and the thickness of the piezoelectric body 2 is such that vibration propagates inside the piezoelectric body 2. It is preferable that it is 70% of a quarter of the wavelength. “70% of a quarter of the wavelength” means 17.5% of the wavelength. Note that “70% of a quarter of the wavelength” is a value including an error of ± 5%. When the thickness of the piezoelectric body 2 and the thickness of the acoustic matching layer 3 satisfy the above relationship, the node point of vibration by the vibrating body 101 can be easily positioned on the support plate 1.
　（実施の形態２）
　図６および図７を参照して、本発明に基づく実施の形態２における振動体アレイ２０１について説明する。本実施の形態における振動体アレイ２０１の断面図を図６に示し、平面図を図７に示す。本実施の形態における振動体アレイに含まれる振動体の個々の基本的な構成は、実施の形態１で説明した構成と同様であるが、実施の形態１に比べて以下の点で異なる。本実施の形態における振動体アレイ２０１では、１つの支持板１に対して、複数の圧電体２と、複数の音響整合層３とが設けられている。 (Embodiment 2)
With reference to FIG. 6 and FIG. 7, vibrator array 201 in the second embodiment based on the present invention will be described. A cross-sectional view of the vibrator array 201 in the present embodiment is shown in FIG. 6, and a plan view is shown in FIG. The individual basic configurations of the vibrating bodies included in the vibrating body array in the present embodiment are the same as those described in the first embodiment, but differ in the following points from the first embodiment. In the vibrator array 201 in the present embodiment, a plurality of piezoelectric bodies 2 and a plurality of acoustic matching layers 3 are provided for one support plate 1.
　振動体アレイ２０１は、図７に示すように、複数の音響整合層３が２×３のマトリックス状に配列されている。複数の圧電体２は、支持板１に対して上述の複数の音響整合層３とそれぞれ１対１で対向するように配列されている。図６に示すように、複数の圧電体２は、相互に間隙１３を介して近接して配置されている。音響整合層３は、相互に間隙１４を介して近接して配置されている。図６では、配線および端子は図示省略している。 As shown in FIG. 7, the vibrating body array 201 has a plurality of acoustic matching layers 3 arranged in a 2 × 3 matrix. The plurality of piezoelectric bodies 2 are arranged so as to face the support plate 1 in a one-to-one correspondence with the plurality of acoustic matching layers 3 described above. As shown in FIG. 6, the plurality of piezoelectric bodies 2 are arranged close to each other with a gap 13 therebetween. The acoustic matching layers 3 are arranged close to each other with a gap 14 therebetween. In FIG. 6, wirings and terminals are not shown.
　振動体アレイ２０１による振動のノード点は、支持板１の内部に位置している。具体的には、振動体１０１による振動のノード点が支持板１に位置するように、複数の音響整合層３の厚みに対する複数の圧電体２の厚みが設定されている。以下に一例を示す。音響整合層３の内部を伝播する振動の周波数は、たとえば２６８ｋＨｚであり、圧電体２の内部を伝播する振動の周波数は、たとえば３８０ｋＨｚである。振動が圧電体２の中を伝播するときの波長をλ1とすると、複数の圧電体２の厚みは、たとえばλ1の４分の１である。振動が音響整合層３の中を伝播するときの波長をλ2とすると、複数の音響整合層３の厚みは、たとえばλ2の４分の１の７０％である。なお、λ2の４分の１の７０％は、±５％の誤差を含む値である。 The node point of vibration by the vibrator array 201 is located inside the support plate 1. Specifically, the thicknesses of the plurality of piezoelectric bodies 2 with respect to the thicknesses of the plurality of acoustic matching layers 3 are set so that the node points of vibration by the vibrating body 101 are positioned on the support plate 1. An example is shown below. The frequency of vibration propagating through the acoustic matching layer 3 is, for example, 268 kHz, and the frequency of vibration propagating through the piezoelectric body 2 is, for example, 380 kHz. If the wavelength at which vibration propagates through the piezoelectric body 2 is λ 1 , the thickness of the plurality of piezoelectric bodies 2 is, for example, ¼ of λ 1 . If the wavelength at which vibration propagates through the acoustic matching layer 3 is λ 2 , the thickness of the plurality of acoustic matching layers 3 is, for example, 70% of ¼ of λ 2 . Note that 70% of ¼ of λ 2 is a value including an error of ± 5%.
　複数の圧電体２はいずれも同じ厚みである。複数の音響整合層３はいずれも同じ厚みである。 The plurality of piezoelectric bodies 2 are all the same thickness. All of the plurality of acoustic matching layers 3 have the same thickness.
　図７では、複数の音響整合層３として２×３の合計６個の音響整合層３がマトリックス状に配列されている例を示したが、複数の音響整合層３の個数および配列パターンはここで示したものに限らない。 Although FIG. 7 shows an example in which a total of six acoustic matching layers 3 of 2 × 3 are arranged as a plurality of acoustic matching layers 3, the number and arrangement pattern of the plurality of acoustic matching layers 3 are here. It is not restricted to what was shown by.
　本実施の形態では、実施の形態１と同様に、超音波の送信および受信を行なうことができる。すなわち、支持板１と電極５との間に電圧を印加することによって複数の圧電体２は変形し、この振動は、支持板１を介して複数の音響整合層３へと伝わり、複数の音響整合層３が振動することによって、超音波が外部に放出される。こうして送信が行なわれる。本実施の形態では、振動体の単体ではなく振動体アレイとなっているので、広い面積にわたって超音波を発することができる。また、個々の振動体が有する振動特性は振動体アレイ全体においては平均化されるので、個々の振動体の振動特性のばらつきの影響を小さくすることができる。 In the present embodiment, as in the first embodiment, transmission and reception of ultrasonic waves can be performed. That is, by applying a voltage between the support plate 1 and the electrode 5, the plurality of piezoelectric bodies 2 are deformed, and this vibration is transmitted to the plurality of acoustic matching layers 3 via the support plate 1, thereby As the matching layer 3 vibrates, ultrasonic waves are emitted to the outside. Transmission is thus performed. In the present embodiment, since the vibration body array is used instead of a single vibration body, ultrasonic waves can be emitted over a wide area. In addition, since the vibration characteristics of individual vibrators are averaged over the whole vibrator array, the influence of variations in the vibration characteristics of the individual vibrators can be reduced.
　ここでは、複数の圧電体２に電圧を印加して振動させ、複数の音響整合層３から超音波を送信する場合について説明したが、複数の音響整合層３から超音波を受信して複数の圧電体２において電気信号に変換する場合にも同様であり、保持による振動特性の減衰を抑えた振動体を実現することができる。 Here, a case has been described in which a voltage is applied to a plurality of piezoelectric bodies 2 to vibrate, and ultrasonic waves are transmitted from a plurality of acoustic matching layers 3. The same applies to the case where the piezoelectric body 2 converts it into an electrical signal, and it is possible to realize a vibration body that suppresses attenuation of vibration characteristics due to holding.
　特に１対の振動体アレイ同士を互いに対向させて一方を送信側、他方を受信側として用いるような場合には、振動体の単体ではなく振動体アレイであることによる特性ばらつき平均化の利点が大きい。 In particular, when a pair of vibrator arrays are opposed to each other and one is used as a transmitting side and the other is used as a receiving side, there is an advantage of characteristic variation averaging due to the vibrator array instead of a single vibrator. large.
　なお、複数の音響整合層３の厚みは、振動が複数の音響整合層３の中を伝播するときの波長の４分の１であり、複数の圧電体２の厚みは、振動が複数の圧電体２の中を伝播するときの波長の４分の１の７０％であることが好ましい。「波長の４分の１の７０％」とは、波長の１７．５％である。なお、「波長の４分の１の７０％」といった場合は、±５％の誤差を含む値である。複数の圧電体２および複数の音響整合層３の厚みが上述の関係を満たすことにより、振動体による振動のノード点を容易に支持板１に位置させることができる。 The thickness of the plurality of acoustic matching layers 3 is a quarter of the wavelength when vibration propagates through the plurality of acoustic matching layers 3, and the thickness of the plurality of piezoelectric bodies 2 is the thickness of the plurality of piezoelectric matching layers 3. It is preferably 70% of one quarter of the wavelength when propagating through the body 2. “70% of a quarter of the wavelength” means 17.5% of the wavelength. Note that “70% of a quarter of the wavelength” is a value including an error of ± 5%. When the thicknesses of the plurality of piezoelectric bodies 2 and the plurality of acoustic matching layers 3 satisfy the above relationship, the node point of vibration by the vibrating body can be easily positioned on the support plate 1.
　（実施の形態３）
　図８～図１０を参照して、本発明に基づく実施の形態３における振動体アレイについて説明する。本実施の形態では、基本的な構成は、実施の形態２で説明した構成と同様であるが、実施の形態２に比べて以下の点で異なる。 (Embodiment 3)
With reference to FIGS. 8 to 10, a vibrator array according to the third embodiment of the present invention will be described. In the present embodiment, the basic configuration is the same as the configuration described in the second embodiment, but differs from the second embodiment in the following points.
　本実施の形態における振動体アレイは平面図で示すと図８のようになる。図８におけるＩＸ－ＩＸ線に関する矢視断面図は図９のようになる。図８では、音響整合層３が配置された側の面が示されていたが、これと反対側の面は、図１０に示すようになる。 The vibrator array in the present embodiment is shown in a plan view as shown in FIG. FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. In FIG. 8, the surface on which the acoustic matching layer 3 is disposed is shown, but the surface on the opposite side is as shown in FIG.
　本実施の形態では、２×１２の合計２４個の音響整合層３が一体的な板材から作り出されている。すなわち、図８および図９に示すように一体的な板材に切込み９を入れることによって２４個の音響整合層３に切り分けられている。切込み９は板材を完全に切断することなく、一部つながった状態で残している。したがって、２４個の音響整合層３は散逸することなく一体物として扱うことができ、一体物のまま支持板１に接着剤で貼り付けられている。２４個の音響整合層３の塊は、長辺側に断続的に段差部４を有している。音響整合層３が有する複数の面のうち支持板１に貼り付けられている面を「一方主面」とすると、段差部４は、一方主面に接する音響整合層３の面、すなわち、音響整合層３の側面から外側に向かって張り出している凸部である。段差部４は音響整合層３と一体形成されている。段差部４の一方主面側の面は、音響整合層３の一方主面から連なっている平面である。 In the present embodiment, a total of 24 acoustic matching layers 3 of 2 × 12 are produced from an integral plate material. That is, as shown in FIGS. 8 and 9, 24 acoustic matching layers 3 are cut by making cuts 9 in an integral plate. The notch 9 is left in a partially connected state without completely cutting the plate material. Therefore, the 24 acoustic matching layers 3 can be handled as an integral body without being dissipated, and are adhered to the support plate 1 with an adhesive as it is. The block of 24 acoustic matching layers 3 has stepped portions 4 intermittently on the long side. If a surface of the plurality of surfaces of the acoustic matching layer 3 that is attached to the support plate 1 is “one main surface”, the stepped portion 4 is the surface of the acoustic matching layer 3 that is in contact with the one main surface, that is, acoustic. It is a convex portion protruding outward from the side surface of the matching layer 3. The step portion 4 is formed integrally with the acoustic matching layer 3. The surface on the one main surface side of the stepped portion 4 is a flat surface continuing from the one main surface of the acoustic matching layer 3.
　本実施の形態では、圧電体２に関しても、図９および図１０に示すように一体的な圧電材料の板材に切込み１１を入れることによって２４個の圧電体２に切り分けられている。切込み１１は圧電材料の板材を完全に切断することなく、一部つながった状態で残している。したがって、２４個の圧電体２は散逸することなく一体物として扱うことができ、一体物のまま支持板１に貼り付けられている。 In the present embodiment, the piezoelectric body 2 is also divided into 24 piezoelectric bodies 2 by making cuts 11 in an integral piezoelectric material plate as shown in FIGS. The cut 11 is left in a partially connected state without completely cutting the piezoelectric material plate. Therefore, the 24 piezoelectric bodies 2 can be handled as an integral body without being dissipated, and are attached to the support plate 1 as an integral body.
　なお、上述の実施の形態では、圧電素子はチタン酸ジルコン酸鉛系セラミックスからなるものとしているが、圧電素子の材料はこれに限るものではない。たとえば、ニオブ酸カリウムナトリウム系、アルカリニオブ酸系セラミックスなどの非鉛系圧電セラミックスの圧電材料などからなるものであってもよい。 In the above embodiment, the piezoelectric element is made of a lead zirconate titanate ceramic, but the material of the piezoelectric element is not limited to this. For example, it may be made of a lead-free piezoelectric ceramic piezoelectric material such as potassium sodium niobate or alkali niobate ceramic.
　なお、今回開示した上記実施の形態はすべての点で例示であって制限的なものではない。本発明の範囲は上記した説明ではなくて請求の範囲によって示され、請求の範囲と均等の意味および範囲内でのすべての変更を含むものである。 It should be noted that the above-described embodiment disclosed herein is illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
　１　支持板、１ａ　第１主面、１ｂ　第２主面、２　圧電体、３　音響整合層、５，６　電極、９，１１　切込み、１３，１４　間隙、１５　ノード点、３１　ブロック、６１，６２　端子、９１，９２，９３，９４，９５　矢印、１０１　振動体、２０１　振動体アレイ。 1 support plate, 1a 1st main surface, 1b 2nd main surface, 2 piezoelectric body, 3 acoustic matching layer, 5, 6 electrodes, 9, 11 notches, 13, 14 gap, 15 node points, 31 blocks, 61, 62 Terminal, 91, 92, 93, 94, 95 arrow, 101 vibrator, 201 vibrator array.

Claims (4)

  1. 　第１主面および前記第１主面とは反対側を向く第２主面を有する支持板と、
    　前記支持板の前記第１主面に設けられている圧電体と、
    　前記圧電体と対向するように前記支持板の前記第２主面に設けられている音響整合層とを備える振動体であって、
    　前記振動体による振動のノード点が前記支持板に位置するように、前記音響整合層の厚みおよび前記圧電体の厚みが設定されている、振動体。     A support plate having a first main surface and a second main surface facing away from the first main surface;
    A piezoelectric body provided on the first main surface of the support plate;
    A vibrating body including an acoustic matching layer provided on the second main surface of the support plate so as to face the piezoelectric body,
    A vibrating body in which a thickness of the acoustic matching layer and a thickness of the piezoelectric body are set so that a node point of vibration by the vibrating body is located on the support plate.
  2. 　前記音響整合層の厚みは、振動が前記音響整合層の中を伝播するときの波長の４分の１であり、
    　前記圧電体の厚みは、振動が前記圧電体の中を伝播するときの波長の４分の１の７０％である、請求項１に記載の振動体。     The thickness of the acoustic matching layer is a quarter of the wavelength at which vibration propagates through the acoustic matching layer,
    2. The vibrating body according to claim 1, wherein the thickness of the piezoelectric body is 70% that is a quarter of a wavelength when vibration propagates through the piezoelectric body.
  3. 　第１主面および前記第１主面とは反対側を向く第２主面を有する支持板と、
    　前記支持板の前記第１主面に設けられ、前記第１主面に沿って配列されている複数の圧電体と、
    　前記複数の圧電体とそれぞれ１対１で対向するように前記支持板の前記第２主面に設けられ、前記第２主面に沿って配列されている複数の音響整合層とを備え、
    　前記複数の圧電体と前記複数の音響整合層とのうち前記支持板を挟んで互いに対応する位置にあるもの同士の１対１の組合せをそれぞれ振動体と定義したとき、
    　前記振動体による振動のノード点が前記支持板に位置するように、前記複数の音響整合層の厚みおよび前記複数の圧電体の厚みが設定されている、振動体アレイ。     A support plate having a first main surface and a second main surface facing away from the first main surface;
    A plurality of piezoelectric bodies provided on the first main surface of the support plate and arranged along the first main surface;
    A plurality of acoustic matching layers provided on the second main surface of the support plate so as to face the plurality of piezoelectric bodies on a one-to-one basis, and arranged along the second main surface;
    When a one-to-one combination of the plurality of piezoelectric bodies and the plurality of acoustic matching layers at positions corresponding to each other across the support plate is defined as a vibrator,
    The vibrator array in which the thicknesses of the plurality of acoustic matching layers and the thicknesses of the plurality of piezoelectric bodies are set so that node points of vibration by the vibrator are located on the support plate.
  4. 　前記複数の音響整合層の各々の厚みは、前記縦振動が前記複数の音響整合層の中を伝播するときの波長の４分の１であり、
    　前記複数の圧電体の各々の厚みは、前記縦振動が前記複数の圧電体の中を伝播するときの波長の４分の１の７０％である、請求項３に記載の振動体アレイ。     The thickness of each of the plurality of acoustic matching layers is a quarter of the wavelength at which the longitudinal vibration propagates through the plurality of acoustic matching layers,
    4. The vibrating body array according to claim 3, wherein the thickness of each of the plurality of piezoelectric bodies is 70% that is a quarter of a wavelength when the longitudinal vibration propagates through the plurality of piezoelectric bodies.
PCT/JP2015/084396 2014-12-12 2015-12-08 Vibrating body and vibrating body array WO2016093228A1 (en)

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WO2020216004A1 (en) * 2019-04-23 2020-10-29 维沃移动通信有限公司 Terminal device and vibration control method

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JPS6041399A (en) * 1983-08-16 1985-03-05 Toshiba Corp Ultrasonic probe
JP2002010394A (en) * 2000-06-20 2002-01-11 Murata Mfg Co Ltd Ultrasonic sensor, electronic apparatus using its and its manufacturing method
JP2009128290A (en) * 2007-11-27 2009-06-11 Ricoh Elemex Corp Ultrasonic sensor

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Publication number Priority date Publication date Assignee Title
JPS6041399A (en) * 1983-08-16 1985-03-05 Toshiba Corp Ultrasonic probe
JP2002010394A (en) * 2000-06-20 2002-01-11 Murata Mfg Co Ltd Ultrasonic sensor, electronic apparatus using its and its manufacturing method
JP2009128290A (en) * 2007-11-27 2009-06-11 Ricoh Elemex Corp Ultrasonic sensor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020216004A1 (en) * 2019-04-23 2020-10-29 维沃移动通信有限公司 Terminal device and vibration control method

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