JP2010252017A

JP2010252017A - Ultrasonic transmitter-receiver

Info

Publication number: JP2010252017A
Application number: JP2009098792A
Authority: JP
Inventors: Yuki Hamaguchi; 佑樹浜口; Haruo Yamamori; 春男山森; Haruhisa Hirose; 晴久広瀬; Yuichi Maita; 雄一舞田; Sachihiro Aoki; 祥博青木; Tonshaku To; 敦灼董; Yuki Murai; 勇気村井; Hiroki Kitagawa; 弘樹北川
Original assignee: Honda Electronics Co Ltd
Current assignee: Honda Electronics Co Ltd
Priority date: 2009-04-15
Filing date: 2009-04-15
Publication date: 2010-11-04
Anticipated expiration: 2029-04-15
Also published as: JP5332059B2

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic transmitter-receiver with excellent transmission characteristics and reception characteristics even if it serves as the ultrasonic transmitter-receiver for transmitting and receiving ultrasonic waves. SOLUTION: The ultrasonic transmitter-receiver includes a plurality of piezoelectric elements for transmission, a plurality of piezoelectric elements for reception, and an ultrasonic transmission member. The piezoelectric elements for transmission have a dimension in a thickness direction larger than a dimension in a radial direction, have characteristics of mechanically resonating at a prescribed frequency in the thickness direction, and are electrically connected in parallel to each other. The piezoelectric elements for reception have a dimension in the thickness direction larger than a dimension in the radial direction, have characteristics of mechanically anti-resonating at the prescribed frequency in the thickness direction, and are electrically connected in parallel to each other. COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、魚群探知機用の水中超音波センサや空中超音波センサなど、液中や空中での超音波の送波と受波を行う、超音波送受装置に関する。 The present invention relates to an ultrasonic transmission / reception apparatus that transmits and receives ultrasonic waves in a liquid or in the air, such as an underwater ultrasonic sensor or an aerial ultrasonic sensor for a fish finder.

従来より、自身で超音波の送波と受波とを行う超音波センサが知られている（特許文献１参照）。 Conventionally, an ultrasonic sensor that transmits and receives ultrasonic waves by itself is known (see Patent Document 1).

特開２００４−１０４５２１号公報JP 2004-104521 A

しかしながら、この超音波センサでは、１つの圧電素子を、超音波の送波（超音波の発生）にも、受波（超音波を電圧信号に変換）にも用いる。このため、両方の特性のバランスを考慮して、圧電素子の寸法や特性を選択することとなり、十分な特性を得られていなかった。 However, in this ultrasonic sensor, one piezoelectric element is used for both the transmission of ultrasonic waves (generation of ultrasonic waves) and the reception of waves (converting ultrasonic waves into voltage signals). For this reason, the dimensions and characteristics of the piezoelectric element are selected in consideration of the balance of both characteristics, and sufficient characteristics cannot be obtained.

本発明は、かかる問題点に鑑みてなされたものであって、超音波の送波と受波とを行う超音波送受波装置でありながら、送波特性も受波特性も良好な超音波送受波装置を提供することにある。 The present invention has been made in view of such a problem, and is an ultrasonic transmission / reception apparatus that performs ultrasonic transmission and reception, but has excellent transmission characteristics and reception characteristics. The object is to provide a sound wave transmitting / receiving apparatus.

その一態様は、複数の送波用圧電素子と、複数の受波用圧電素子と、上記送波用圧電素子及び上記受波用圧電素子が固着された固着面、及び、超音波を送波及び受波する超音波送受波面を有し、上記送波用圧電素子で発生させた超音波を、上記固着面から上記超音波送受波面に伝えて、この超音波送受波面から放射させ、上記超音波送受波面に届いた超音波を、この上記超音波送受波面から上記固着面を通じて、上記受波用圧電素子に伝える超音波伝達部材と、を備える超音波送受波装置であって、複数の上記送波用圧電素子は、各々、上記固着面に直交する厚み方向の寸法が、上記固着面に平行な径方向の寸法よりも大きくされ、上記厚み方向に、所定周波数で機械的に共振する特性を有し、電気的に互いに並列に接続されてなり、複数の上記受波用圧電素子は、各々、上記厚み方向の寸法が、上記径方向の寸法よりも大きくされ、上記厚み方向に、上記所定周波数で機械的に反共振する特性を有し、電気的に互いに並列に接続されてなる超音波送受波装置である。 One aspect thereof includes a plurality of transmitting piezoelectric elements, a plurality of receiving piezoelectric elements, a fixing surface to which the transmitting piezoelectric element and the receiving piezoelectric element are fixed, and transmitting ultrasonic waves. And an ultrasonic wave transmitting / receiving surface for receiving waves, and transmitting the ultrasonic wave generated by the piezoelectric element for wave transmission from the fixed surface to the ultrasonic wave transmitting / receiving surface, and radiating from the ultrasonic wave transmitting / receiving surface, An ultrasonic transmission / reception apparatus comprising: an ultrasonic transmission member that transmits ultrasonic waves that have arrived at the ultrasonic transmission / reception surface from the ultrasonic transmission / reception surface to the piezoelectric element for reception through the fixing surface, Each of the piezoelectric elements for wave transmission has a characteristic that the dimension in the thickness direction perpendicular to the fixing surface is larger than the dimension in the radial direction parallel to the fixing surface, and mechanically resonates at a predetermined frequency in the thickness direction. And electrically connected in parallel with each other, and a plurality of Each of the piezoelectric elements for receiving waves has a characteristic that the dimension in the thickness direction is larger than the dimension in the radial direction, and mechanically resonates at the predetermined frequency in the thickness direction. It is an ultrasonic transmission / reception apparatus connected in parallel with each other.

この超音波送受波装置では、複数の送波用圧電素子は、各々、固着面に直交する厚み方向の寸法が、固着面に平行な径方向の寸法よりも大きくされている。このため、所定周波数で、この送波用圧電素子を共振させた場合に、径方向に副共振などが生じにくく、厚み方向の共振を選択的に生じさせることができる。さらに、各々の送波用圧電素子が、電気的に互いに並列に接続されてなるので、複数の送波用圧電素子を同期して駆動して、複数の送波用圧電素子全体で、均一な厚み振動（超音波振動）を誘起して、径方向に均一な超音波を発生、放射することができる。
また、複数の受波用圧電素子も、各々、厚み方向の寸法が、径方向の寸法よりも大きくされている。このため、所定周波数で、この受波用圧電素子を反共振させた場合でも、径方向に副共振などが生じにくく、厚み方向の反共振を選択的に生じさせることができる。さらに、各々の受波用圧電素子が、電気的に互いに並列に接続されてなるので、複数の受波用圧電素子全体で、効果的に超音波を検知できる。
さらに、複数の送波用圧電素子は、所定周波数で、厚み方向の共振を生じる。一方、複数の受波用圧電素子は、これと同じ所定周波数で、厚み方向に反共振する。このため、この所定周波数で、インピーダンスの低い複数の送波用圧電素子を駆動することにより、振幅の大きな超音波を発生させることができる。その一方、反射波など、送波したのと同じ、所定周波数の超音波を、インピーダンスの高い複数の受波用圧電素子で、効果的に受波し、大きな超音波信号を得ることができる。
かくして、送波特性も受波特性も良好な超音波送受波装置を得ることができる。 In this ultrasonic transmission / reception device, the plurality of piezoelectric elements for transmission each have a dimension in the thickness direction perpendicular to the fixing surface larger than a dimension in the radial direction parallel to the fixing surface. For this reason, when this transmitting piezoelectric element is resonated at a predetermined frequency, sub-resonance and the like hardly occur in the radial direction, and resonance in the thickness direction can be selectively generated. Furthermore, since each of the piezoelectric elements for transmission is electrically connected in parallel with each other, the plurality of piezoelectric elements for transmission are driven in synchronization, and the entire plurality of piezoelectric elements for transmission are uniform. Thickness vibration (ultrasonic vibration) can be induced to generate and radiate uniform ultrasonic waves in the radial direction.
In addition, each of the plurality of receiving piezoelectric elements also has a dimension in the thickness direction larger than a dimension in the radial direction. For this reason, even when the receiving piezoelectric element is anti-resonated at a predetermined frequency, sub-resonance or the like hardly occurs in the radial direction, and anti-resonance in the thickness direction can be selectively generated. Furthermore, since each of the receiving piezoelectric elements is electrically connected in parallel with each other, the ultrasonic waves can be effectively detected by the plurality of receiving piezoelectric elements as a whole.
Furthermore, the plurality of piezoelectric elements for transmission generate resonance in the thickness direction at a predetermined frequency. On the other hand, the plurality of receiving piezoelectric elements are anti-resonant in the thickness direction at the same predetermined frequency. For this reason, it is possible to generate ultrasonic waves having a large amplitude by driving a plurality of low-impedance transmission piezoelectric elements at this predetermined frequency. On the other hand, a large ultrasonic signal can be obtained by effectively receiving ultrasonic waves of a predetermined frequency, such as reflected waves, with a plurality of receiving piezoelectric elements having high impedance.
Thus, it is possible to obtain an ultrasonic wave transmission / reception device having good transmission characteristics and reception characteristics.

なお、複数の送波用圧電素子は、各々、厚み方向の寸法が、径方向の寸法よりも大きくされ、厚み方向に、所定周波数で機械的に共振する特性を有していればよい。
また同様に、複数の受波用圧電素子も、各々、厚み方向の寸法が、径方向の寸法よりも大きくされ、厚み方向に、所定周波数で機械的に反共振する特性を有していればよい。
従って、各々の各送波用圧電素子、あるいは各々の各受波用圧電素子を、互いに独立に、プレス、焼成、分極等して製造しても良い。また、一旦、平板状の大型素子を作製し、切断後に分極して、あるいは、分極後に切断して、複数の送波用圧電素子を得ても良い。特に、大型素子を作成する後者の手法では、厚み方向寸法や特性が均一になりやすく好ましい。中でも、分極後に切断する場合には、分極を大型素子について行えばよいので、より製造が容易である。 Each of the plurality of piezoelectric elements for wave transmission only needs to have a characteristic that the dimension in the thickness direction is larger than the dimension in the radial direction and mechanically resonates at a predetermined frequency in the thickness direction.
Similarly, each of the plurality of receiving piezoelectric elements has a characteristic that the dimension in the thickness direction is larger than the dimension in the radial direction and mechanically resonates at a predetermined frequency in the thickness direction. Good.
Accordingly, each of the transmitting piezoelectric elements or each of the receiving piezoelectric elements may be manufactured independently of each other by pressing, firing, polarization, or the like. Alternatively, a plurality of piezoelectric elements for transmission may be obtained by once producing a flat large element and polarizing it after cutting or by cutting after polarization. In particular, the latter method of producing a large element is preferable because the thickness direction dimension and characteristics are likely to be uniform. In particular, in the case of cutting after polarization, the polarization can be performed on a large element, so that the manufacture is easier.

さらに、送波用圧電素子及び受波用圧電素子の材質としては、適宜の圧電セラミックスを用いることができ、チタン酸鉛（ＰｂＴｉＯ₃）、チタン酸ジルコン酸鉛（Ｐｂ(ＺｒＴｉ）Ｏ₃）などの鉛系圧電セラミックス，チタン酸バリウム（ＢａＴｉＯ₃），Ｂｉ_0.5Ｎａ_0.5ＴｉＯ₃（ＢＮＴ），(１−ｘ−ｙ)(Ｂｉ_0.5Ｎａ_0.5)ＴｉＯ₃−ｘＢａＴｉＯ₃−ｙ(Ｂｉ_0.5Ｎａ_0.5)(Ｍｎ_1/3Ｎｂ_2/3)Ｏ₃（ＢＮＴ−ＢＴ−ＢＮＭＮ）などの無鉛圧電セラミックスなどを用いることができる。
また、送波用圧電素子と受波用圧電素子とは、同じ材質の圧電セラミックスで構成しても良いし、異なる材質の圧電セラミックスを用いても良い。なお、同じ材質の圧電セラミックスを用いた場合には、送波用圧電素子の厚み方向寸法に比して、受波用圧電素子の厚み方向寸法が大きくなる。 Furthermore, suitable piezoelectric ceramics can be used as the material of the transmitting piezoelectric element and the receiving piezoelectric element, such as lead titanate (PbTiO ₃ ) and lead zirconate titanate (Pb (ZrTi) O ₃ ). Lead-based piezoelectric ceramics, barium titanate (BaTiO ₃ ), Bi _0.5 Na _0.5 TiO ₃ (BNT), (1-xy) (Bi _0.5 Na _0.5 ) TiO ₃ —xBaTiO ₃ —y (Bi _0.5 Na _0.5 ) Lead-free piezoelectric ceramics such as (Mn _1/3 Nb _2/3 ) O ₃ (BNT-BT-BNMN) can be used.
Further, the transmitting piezoelectric element and the receiving piezoelectric element may be composed of piezoelectric ceramics of the same material, or piezoelectric ceramics of different materials may be used. When piezoelectric ceramics of the same material are used, the thickness direction dimension of the receiving piezoelectric element is larger than the thickness direction dimension of the transmitting piezoelectric element.

さらに、複数の送波用圧電素子と複数の受波用圧電素子の配置としては、送波用圧電素子同士を１個所に集めて配置する一方、受波用圧電素子同士を他の一個所に集めて配置すると、各素子の結線が容易となる。
一方、複数の送波用圧電素子と複数の受波用圧電素子とを混在させて配置しても良い。 Furthermore, as for the arrangement of the plurality of transmitting piezoelectric elements and the plurality of receiving piezoelectric elements, the transmitting piezoelectric elements are collected and arranged in one place, while the receiving piezoelectric elements are arranged in the other place. When they are collected and arranged, each element can be easily connected.
On the other hand, a plurality of piezoelectric elements for transmission and a plurality of piezoelectric elements for reception may be mixed.

また、各送波用圧電素子及び受波用圧電素子同士の間には、絶縁性で、柔らかいゴム弾性を有するあるいは発泡性の樹脂材を配置して、異物侵入や水分侵入による短絡等の不具合を防止すると良い。
さらに、送波用圧電素子と受波用圧電素子とは、固着面に固着された総面積で比較した場合に、同じであっても、一方が大きくても良い。従って、各素子の固着面積が同じである場合には、素子の数を同数としても良いし、一方が多くても良い。
また、超音波伝達部材の材質としては、金属、樹脂、ゴム等を用いることができ、その強度や使用環境、超音波を伝える媒体（水、空気など）及び圧電素子（送波用圧電素子、受波用圧電素子）の音響インピーダンス等を考慮して、選択すると良い。 Also, between each transmitting piezoelectric element and receiving piezoelectric element, an insulating, soft rubber elastic or foaming resin material is arranged, and there is a problem such as a short circuit due to intrusion of foreign matter or moisture. It is good to prevent.
Furthermore, the piezoelectric element for transmission and the piezoelectric element for reception may be the same or larger when compared with the total area fixed to the fixing surface. Therefore, when the fixing area of each element is the same, the number of elements may be the same, or one may be larger.
In addition, as a material of the ultrasonic transmission member, metal, resin, rubber, or the like can be used, and its strength and usage environment, medium for transmitting ultrasonic waves (water, air, etc.) and a piezoelectric element (a piezoelectric element for transmission, It may be selected in consideration of the acoustic impedance of the receiving piezoelectric element).

また、上述の超音波送受波装置であって、前記複数の受波用圧電素子を内側に、前記複数の送波用圧電素子を上記受波用圧電素子の外周を囲む形態に配置してなる超音波送受波装置とすると良い。 Further, in the above-described ultrasonic transmission / reception device, the plurality of reception piezoelectric elements are arranged inside, and the plurality of transmission piezoelectric elements are arranged so as to surround an outer periphery of the reception piezoelectric element. An ultrasonic transmission / reception device is preferable.

この超音波送受波装置では、リング状に配置した複数の送波用圧電素子で超音波を発生させ放射する。その一方、反射して戻った超音波を、送波用圧電素子の内側に集められた複数の受波用圧電素子で受波できるので、放射される超音波の放射方向と、受波できる超音波の方向とにずれが無く、自身が放射した超音波が反射して戻った超音波を、効果的に受波することができる。 In this ultrasonic wave transmitting / receiving apparatus, ultrasonic waves are generated and emitted by a plurality of transmitting piezoelectric elements arranged in a ring shape. On the other hand, since the reflected ultrasonic waves can be received by a plurality of receiving piezoelectric elements collected inside the transmitting piezoelectric element, the radiation direction of the emitted ultrasonic waves and the ultrasonic waves that can be received There is no deviation in the direction of the sound wave, and it is possible to effectively receive the ultrasonic wave reflected and returned by the ultrasonic wave radiated by itself.

なお、送波用圧電素子及び受波用圧電素子の形状は、固着面を平面視したとき、矩形となる形態とするのがよい。各素子を格子状に容易に配置できるからである。
特に、各送波用圧電素子及び受波用圧電素子が、同寸の正方形となる形態とするのがよい。各素子を格子状に容易に配置できる上、各素子間を密に配置できる利点がある。 The shape of the transmitting piezoelectric element and the receiving piezoelectric element is preferably rectangular when the fixed surface is viewed in plan. This is because each element can be easily arranged in a grid pattern.
In particular, it is preferable that each transmitting piezoelectric element and receiving piezoelectric element have a square shape of the same size. Each element can be easily arranged in a lattice pattern, and there is an advantage that each element can be arranged densely.

第１の実施形態にかかる超音波送受波装置の側方から見た構造を示す説明図である。It is explanatory drawing which shows the structure seen from the side of the ultrasonic transmission / reception apparatus concerning 1st Embodiment. 第１の実施形態にかかる超音波送受波装置の正面から見た構造を示す説明図である。It is explanatory drawing which shows the structure seen from the front of the ultrasonic transmission / reception apparatus concerning 1st Embodiment. 送波素子と受波素子の周波数−インピーダンス特性を示す説明図である。It is explanatory drawing which shows the frequency-impedance characteristic of a transmitting element and a receiving element. 第２の実施形態にかかる超音波送受波装置の側方から見た構造を示す説明図である。It is explanatory drawing which shows the structure seen from the side of the ultrasonic transmission / reception apparatus concerning 2nd Embodiment. 第２の実施形態にかかる超音波送受波装置の正面から見た構造を示す説明図である。It is explanatory drawing which shows the structure seen from the front of the ultrasonic transmission / reception apparatus concerning 2nd Embodiment.

（実施形態１）
第１の実施形態について、図１及び図２に示す構造の説明図を参照して説明する。
本実施形態の超音波センサ１０は、金属からなる振動板１１と、この振動板１１に固着された、複数（４×４＝１６ヶ）の送波素子１２，及び複数（４×４＝１６ヶ）の受波素子１３からなる。
このうち、振動板１１は、平板形状を有しており、一方の面（図１中、上面）が固着面１１Ａ、他方の面（図１中、下面）が超音波送受波面１１Ｂである。このうち、固着面１１Ａには、送波素子１２及び受波素子１３が固着されている。また、超音波送受波面１１Ｂは、水である媒体ＭＤに接しており、送波超音波ＵＳＳを媒体ＭＤ（水）中に放射し、また、媒体ＭＤ（水）中からの受波超音波ＵＳＲを受ける。 (Embodiment 1)
1st Embodiment is described with reference to explanatory drawing of the structure shown in FIG.1 and FIG.2.
The ultrasonic sensor 10 of this embodiment includes a diaphragm 11 made of metal, a plurality (4 × 4 = 16) of transmitting elements 12 fixed to the diaphragm 11, and a plurality (4 × 4 = 16). ) Receiving element 13.
Among these, the diaphragm 11 has a flat plate shape, and one surface (upper surface in FIG. 1) is a fixing surface 11A, and the other surface (lower surface in FIG. 1) is an ultrasonic wave transmitting / receiving surface 11B. Among these, the transmitting element 12 and the receiving element 13 are fixed to the fixing surface 11A. The ultrasonic wave transmitting / receiving surface 11B is in contact with the medium MD which is water, radiates the ultrasonic wave USS into the medium MD (water), and receives the ultrasonic wave USR received from the medium MD (water). Receive.

本実施形態１では、送波素子１２は合計１６ヶ有り、４段４列の格子状に配置されている。送波素子１２は、互いに同形状の直方体形状であり、詳細には、超音波送波面１２Ａとこれに対向する裏面１２Ｂとがそれぞれ正方形とされた、正四角柱形状とされている。この送波素子１２は、圧電セラミックスからなる。
また、超音波送波面１２Ａには、全面に、焼き付け銀電極からなる送波側電極１２Ｃが形成され、裏面１２Ｂには、同じく全面に焼き付け銀電極からなる裏面側電極１２Ｄが形成されている。この送波素子１２は、図１中、上下方向である厚み方向ＴＤに分極されている。 In the first embodiment, there are a total of 16 transmission elements 12, which are arranged in a four-stage, four-row grid. The wave transmitting element 12 has the same rectangular parallelepiped shape. Specifically, the wave transmitting element 12 has a regular quadrangular prism shape in which the ultrasonic wave transmitting surface 12A and the back surface 12B opposed thereto are square. The wave transmitting element 12 is made of piezoelectric ceramics.
The ultrasonic transmission surface 12A is formed with a transmission-side electrode 12C made of a baked silver electrode on the entire surface, and the back surface 12B is also formed with a back-side electrode 12D made of a baked silver electrode on the entire surface. The wave transmitting element 12 is polarized in the thickness direction TD which is the vertical direction in FIG.

このため、この送波素子１２は、送波側電極１２Ｃと裏面側電極１２Ｄとの間に交流電圧を印加すると、厚み方向に伸縮振動をする。この送波素子１２の周波数−インピーダンス特性を、図３に示す。この送波素子１２は、厚み方向振動に関し、共振周波数ｆｓｒで共振して大きく振動すると共に、そのインピーダンスが大きく低下する。一方、厚み方向振動に関し、反共振周波数ｆｓａで反共振し、振動が最も小さくなると共に、そのインピーダンスが最も高くなる。
なお、この送波素子１２は、その厚み方向ＴＤの寸法、即ち、超音波送波面１２Ａと裏面１２Ｂとの間の厚み方向寸法１２Ｈは、径方向ＤＤ（固着面１１Ａに沿う方向）の寸法、即ち、径方向寸法１２Ｊよりも、大きくされている。
このため、この送波素子１２において、共振周波数ｆｓｒの付近には、径方向に共振したことによる副共振が存在しない。このため、図３に示すように、共振周波数ｆｓｒ付近で、急峻にインピーダンスが低下する特性となっている。 For this reason, the wave transmitting element 12 performs stretching vibration in the thickness direction when an AC voltage is applied between the wave transmitting side electrode 12C and the back surface side electrode 12D. FIG. 3 shows the frequency-impedance characteristics of the transmission element 12. With respect to the vibration in the thickness direction, the transmission element 12 resonates at the resonance frequency fsr and vibrates greatly, and the impedance thereof greatly decreases. On the other hand, the vibration in the thickness direction is antiresonant at the antiresonance frequency fsa, and the vibration becomes the smallest and the impedance becomes the highest.
The wave transmitting element 12 has a dimension in the thickness direction TD, that is, a dimension 12H in the thickness direction between the ultrasonic wave transmitting surface 12A and the back surface 12B, a dimension in the radial direction DD (a direction along the fixing surface 11A), That is, it is made larger than the radial dimension 12J.
Therefore, in this transmission element 12, there is no sub-resonance due to resonance in the radial direction in the vicinity of the resonance frequency fsr. For this reason, as shown in FIG. 3, the impedance sharply decreases near the resonance frequency fsr.

超音波送波面１２Ａ（送波側電極１２Ｃ）が、図示しない接着剤で振動板１１の固着面１１Ａに接着されることにより、各送波素子１２が振動板１１に固着されている。これと共に、送波側電極１２Ｃが、振動板１１に導通している。さらに、送波素子１２同士の間には、柔軟なゴム状弾性を有する介在樹脂材１４が充填されている。 The ultrasonic wave transmission surface 12A (transmission side electrode 12C) is bonded to the fixing surface 11A of the vibration plate 11 with an adhesive (not shown), whereby the respective wave transmission elements 12 are fixed to the vibration plate 11. At the same time, the transmission-side electrode 12 C is electrically connected to the diaphragm 11. Furthermore, an intervening resin material 14 having a flexible rubber-like elasticity is filled between the transmission elements 12.

一方、本実施形態１では、受波素子１３も合計１６ヶ有り、４段４列の格子状に配置されている。受波素子１３も、互いに同形状の直方体形状であり、詳細には、超音波受波面１３Ａとこれに対向する裏面１３Ｂとがそれぞれ正方形とされた、正四角柱形状とされている。しかも、超音波受波面１３Ａと裏面１３Ｂは、送波素子１２における、超音波送波面１２Ａ及び裏面１２Ｂと、同寸法とされている。この受波素子１３も、圧電セラミックスからなる。
また、超音波受波面１３Ａにも、全面に、焼き付け銀電極からなる受波側電極１３Ｃが形成され、裏面１３Ｂにも、同じく全面に焼き付け銀電極からなる裏面側電極１３Ｄが形成されている。この受波素子１３も、図１中、上下方向である厚み方向ＴＤに分極されている。この受波素子１３では、送波素子１２よりも、その厚み方向ＴＤの寸法、即ち、超音波受波面１３Ａと裏面１３Ｂとの間の厚み方向寸法１３Ｈが大きくされている（１３Ｈ＞１２Ｈ）。 On the other hand, in the first embodiment, there are 16 receiving elements 13 in total, and they are arranged in a lattice form of 4 rows and 4 rows. The wave receiving element 13 also has the same rectangular parallelepiped shape. Specifically, the wave receiving element 13 has a regular quadrangular prism shape in which the ultrasonic wave receiving surface 13A and the back surface 13B facing the wave receiving surface 13A are square. In addition, the ultrasonic wave receiving surface 13A and the back surface 13B have the same dimensions as the ultrasonic wave transmitting surface 12A and the back surface 12B in the wave transmitting element 12. The wave receiving element 13 is also made of piezoelectric ceramics.
The ultrasonic wave receiving surface 13A is also formed with a receiving side electrode 13C made of a baked silver electrode on the entire surface, and the back surface 13B is also formed with a back side electrode 13D made of a baked silver electrode on the entire surface. This wave receiving element 13 is also polarized in the thickness direction TD which is the vertical direction in FIG. In the wave receiving element 13, the dimension in the thickness direction TD, that is, the thickness direction dimension 13H between the ultrasonic wave receiving surface 13A and the back surface 13B is larger than that of the wave transmitting element 12 (13H> 12H).

このため、この受波素子１３は、超音波振動を加え、厚み方向に伸縮振動をさせると、受波側電極１３Ｃと裏面側電極１３Ｄとの間に交流電圧が発生する。この受波素子１３の周波数−インピーダンス特性についても、図３に示す。この受波素子１３は、厚み方向振動に関し、共振周波数ｆｒｒで共振して大きく振動するとともに、そのインピーダンスが大きく低下する。一方、厚み方向振動に関し、反共振周波数ｆｒａで反共振してその振動が最も小さくなると共に、そのインピーダンスが最も高くなる。
なお、この受波素子１３も、その厚み方向ＴＤの寸法、即ち、超音波受波面１３Ａと裏面１３Ｂとの間の厚み方向寸法１３Ｈは、径方向ＤＤ（固着面１１Ａに沿う方向）の寸法、即ち、径方向寸法１３Ｊよりも、大きくされている。
このため、この受波素子１２において、反共振周波数ｆｒａの付近に、径方向寸法に共振したことによる副共振が存在しない。このため、図３に示すように、反共振周波数ｆｒａ付近で、急峻にインピーダンスが増加する特性となっている。 For this reason, when the wave receiving element 13 applies ultrasonic vibrations and expands and contracts in the thickness direction, an AC voltage is generated between the wave receiving side electrode 13C and the back side electrode 13D. The frequency-impedance characteristics of the wave receiving element 13 are also shown in FIG. With respect to the vibration in the thickness direction, the wave receiving element 13 resonates at the resonance frequency frr and vibrates greatly, and its impedance is greatly reduced. On the other hand, the vibration in the thickness direction is anti-resonant at the anti-resonance frequency fr and the vibration becomes the smallest and the impedance becomes the highest.
The receiving element 13 also has a dimension in the thickness direction TD, that is, a dimension 13H in the thickness direction between the ultrasonic wave receiving surface 13A and the back surface 13B, the dimension in the radial direction DD (the direction along the fixing surface 11A), That is, it is made larger than the radial dimension 13J.
For this reason, in this wave receiving element 12, there is no sub-resonance due to resonance in the radial dimension in the vicinity of the anti-resonance frequency fr. For this reason, as shown in FIG. 3, the impedance increases steeply in the vicinity of the anti-resonance frequency fr.

超音波送波面１３Ａ（受波側電極１３Ｃ）が、図示しない接着剤で振動板１１の固着面１１Ａに接着されることにより、各受波素子１３も送波素子１２と同じ振動板１１に固着されている。これと共に、受波側電極１３Ｃが、振動板１１に導通している。さらに、受波素子１３同士の間にも、柔軟なゴム状弾性を有する介在樹脂材１４が充填されている。 The ultrasonic wave transmitting surface 13A (the wave receiving side electrode 13C) is bonded to the fixing surface 11A of the diaphragm 11 with an adhesive (not shown), so that each wave receiving element 13 is also fixed to the same diaphragm 11 as the wave transmitting element 12. Has been. At the same time, the receiving electrode 13 C is electrically connected to the diaphragm 11. Furthermore, an intervening resin material 14 having a flexible rubber-like elasticity is filled between the wave receiving elements 13.

しかも、本実施形態１では、送波素子１２の共振周波数ｆｓｒと、受波素子１３の反共振周波数ｆｒａが等しくなるように、送波素子１２の厚み方向寸法１２Ｈと、受波素子１３の厚み方向寸法１３Ｈとを、調整してある。 Moreover, in the first embodiment, the thickness direction dimension 12H of the transmitting element 12 and the thickness of the receiving element 13 are set so that the resonant frequency fsr of the transmitting element 12 and the antiresonant frequency fr of the receiving element 13 are equal. The direction dimension 13H is adjusted.

さらに、各送波素子１２の裏面側電極１２Ｄ同士は、送波側リード線１５で並列にハンダ付けにより接続され、外部に取り出されている。同様に、各受波素子１３の裏面側電極１３Ｄ同士も、受波側リード線１６で並列にハンダ付けにより接続され、外部に取り出されている。さらに、振動板１１の固着面１１Ａにも、共通リード線１７がハンダ付けされている（図１参照）。 Furthermore, the back surface side electrodes 12D of each transmission element 12 are connected by soldering in parallel with the transmission side lead wire 15 and are taken out to the outside. Similarly, the back surface side electrodes 13D of the wave receiving elements 13 are also connected to the wave receiving side lead wires 16 in parallel by soldering and taken out to the outside. Further, the common lead wire 17 is also soldered to the fixing surface 11A of the diaphragm 11 (see FIG. 1).

そこで、超音波電源ＰＳから、本実施形態にかかる超音波センサ１０に、具体的には、送波側リード線１５と共通リード線１７を通じて、並列に接続された各々の送波素子１２に、その信号周波数ＦＲを共振周波数ｆｓｒに一致させたバースト信号（間欠的な正弦電圧）ＳＧＳを印加する。すると、これらの送波素子１２が互いに同期して、厚み方向ＴＤに共振して伸縮し、超音波を発生する。この送波素子１２で発生した超音波（送波超音波ＵＳＳ）は、固着面１１Ａから振動板１１に伝えられ、さらに、超音波送受波面１１Ｂから媒体ＭＤ中（水中）に放射される。この際、バースト信号ＳＧＳの信号周波数ＦＲを、共振周波数ｆｓｒに一致させたので、インピーダンスの低い複数の送波用圧電素子を駆動することにより、振幅の大きな超音波（送波超音波ＵＳＳ）を発生させることができる。 Therefore, from the ultrasonic power source PS to the ultrasonic sensor 10 according to the present embodiment, specifically, to each of the transmission elements 12 connected in parallel through the transmission-side lead wire 15 and the common lead wire 17, A burst signal (intermittent sine voltage) SGS whose signal frequency FR is matched with the resonance frequency fsr is applied. Then, these transmission elements 12 synchronize with each other, resonate in the thickness direction TD, and expand and contract to generate ultrasonic waves. The ultrasonic wave (transmitted ultrasonic wave USS) generated by the wave transmitting element 12 is transmitted from the fixed surface 11A to the diaphragm 11, and further radiated from the ultrasonic wave transmitting / receiving surface 11B into the medium MD (underwater). At this time, since the signal frequency FR of the burst signal SGS is made to coincide with the resonance frequency fsr, an ultrasonic wave having a large amplitude (transmitted ultrasonic wave USS) is generated by driving a plurality of low-impedance transmission piezoelectric elements. Can be generated.

１６ヶ分の送波素子１２と外形がほぼ同形状とした大型圧電素子を用いた場合には、その厚み方向振動のみならず、径方向振動も誘起されがちである。
これに対し、本実施形態では、前述したように、各々の送波素子１２の共振周波数ｆｓｒ付近の周波数特性が良好であり、径方向振動などの副共振が存在しない。厚み方向ＴＤの共振を選択的に生じさせることができる。このため、各送波素子１２の出力を合わせて、大きな振幅の超音波（送波超音波ＵＳＳ）を発生することができる。さらに、各々の送波素子１２が、電気的に互いに並列に接続されてなるので、各送波素子１２が同期して駆動して、複数の送波素子１２全体で、径方向ＤＤに均一な超音波を発生、放射することができる。 In the case of using a large piezoelectric element whose outer shape is substantially the same as that of the 16 transmission elements 12, not only the vibration in the thickness direction but also the radial vibration tends to be induced.
On the other hand, in the present embodiment, as described above, the frequency characteristics in the vicinity of the resonance frequency fsr of each transmission element 12 are good, and there is no sub-resonance such as radial vibration. Resonance in the thickness direction TD can be selectively generated. For this reason, it is possible to generate an ultrasonic wave having a large amplitude (transmitted ultrasonic wave USS) by combining the outputs of the transmission elements 12. Further, since the respective transmitting elements 12 are electrically connected in parallel with each other, the respective transmitting elements 12 are driven in synchronization, and the plurality of transmitting elements 12 as a whole are uniform in the radial direction DD. Ultrasound can be generated and emitted.

さて、放射された送波超音波ＵＳＳが、障害物（たとえば、物体や魚群など）に当たると、一部の超音波が反射される。さらにその一部は、超音波センサ１０に向けて戻る。戻った受波超音波ＵＳＲは、超音波送受波面１１Ｂから振動板１１内に伝わり、その固着面１１Ａを経由して、受波素子１３に伝えられる。 Now, when the emitted transmitted ultrasonic wave USS hits an obstacle (for example, an object or a school of fish), a part of the ultrasonic wave is reflected. Further, a part thereof returns toward the ultrasonic sensor 10. The returned received wave ultrasonic wave USR is transmitted from the ultrasonic wave transmitting / receiving surface 11B into the diaphragm 11, and is transmitted to the wave receiving element 13 via the fixed surface 11A.

すると、受波素子１３には、受波超音波ＵＳＲ（超音波振動）により、電荷が発生する。そこで、この受波信号ＳＧＲを受信装置ＲＣで受信することにより、受波超音波ＵＳＲを検知できる。特に本実施形態では、受波超音波ＵＳＲの周波数は、ちょうど、受波素子１３の反共振周波数ｆｒａに相当している。このため、受波素子１３のインピーダンスが、この受波超音波ＵＳＲの周波数（反共振周波数ｆｒａ）で最大となり、受波素子１３には、大きな電圧の受波信号ＳＧＲが発生する。従って、高い感度で、受波超音波ＵＳＲを検知できる。
特に、受波素子１３も、各々、厚み方向の寸法が、径方向の寸法よりも大きくされているため、この受波素子１３を反共振周波数で駆動した場合でも、径方向に副共振などが生じにくく、厚み方向の反共振を選択的に生じさせることができる。
さらに、各々の受波素子１３を、電気的に互いに並列に接続していので、複数の受波素子１３全体で、効果的に受波超音波ＵＳＲを検知できる。 Then, electric charges are generated in the wave receiving element 13 by the received wave ultrasonic wave USR (ultrasonic vibration). Therefore, the received ultrasonic wave USR can be detected by receiving the received signal SGR with the receiving device RC. In particular, in the present embodiment, the frequency of the received ultrasonic wave USR just corresponds to the anti-resonance frequency fr of the wave receiving element 13. For this reason, the impedance of the wave receiving element 13 becomes maximum at the frequency (anti-resonance frequency fr) of the wave receiving ultrasonic wave USR, and the wave receiving element 13 generates a wave receiving signal SGR having a large voltage. Therefore, the received ultrasonic wave USR can be detected with high sensitivity.
In particular, each of the receiving elements 13 has a dimension in the thickness direction larger than a dimension in the radial direction. Therefore, even when the receiving element 13 is driven at an anti-resonance frequency, there is sub-resonance in the radial direction. Anti-resonance in the thickness direction can be selectively generated without being easily generated.
Furthermore, since each of the receiving elements 13 is electrically connected in parallel with each other, the received ultrasonic waves USR can be effectively detected by the plurality of receiving elements 13 as a whole.

しかも、本実施形態１では、受波素子１３の反共振周波数ｆｒａを、送波素子１２の共振周波数ｆｓｒに一致させ、バースト信号ＳＧＳの周波数を、これらの周波数（共振周波数ｆｓｒ、及び反共振周波数ｆｒａ）としたので、送信素子１２から、大きな振幅の送波超音波ＵＳＳを発生させることができている上、受波素子１３で高い感度で受波超音波ＵＳＲを検知できるので、特に、良好な送受波特性の超音波センサ１０とすることができる。 In addition, in the first embodiment, the anti-resonance frequency fr of the wave receiving element 13 is matched with the resonance frequency fsr of the wave transmitting element 12, and the frequency of the burst signal SGS is changed to these frequencies (resonance frequency fsr and anti-resonance frequency). fra), it is possible to generate a transmission ultrasonic wave USS having a large amplitude from the transmission element 12, and it is possible to detect the reception ultrasonic wave USR with high sensitivity by the reception element 13, which is particularly good. Therefore, the ultrasonic sensor 10 having a proper transmission / reception characteristic can be obtained.

次いで、本実施形態１に係る超音波センサ１０の製造について説明する。
平行平板状の大型の圧電素子を、圧電セラミックスの粉末をプレスし、焼成後研磨して、形成する。その後、その平行な主面にそれぞれ銀ペーストを印刷、焼き付けして、焼
き付け銀電極を作成する。さらに、この銀電極を通じて、油中で直流電圧を印加し、大型の圧電素子を厚み方向に分極する。その後、これを切断して、複数の送波素子１２を得た。受波素子１３についても同様である。 Next, the manufacture of the ultrasonic sensor 10 according to the first embodiment will be described.
A large parallel plate-shaped piezoelectric element is formed by pressing a piezoelectric ceramic powder, firing and polishing. Thereafter, a silver paste is printed and baked on each of the parallel main surfaces to produce a baked silver electrode. Further, a DC voltage is applied in oil through the silver electrode to polarize the large piezoelectric element in the thickness direction. Then, this was cut | disconnected and the several transmission element 12 was obtained. The same applies to the wave receiving element 13.

但し、送波素子１２を得る、分極後の大型の圧電素子における厚み方向の共振周波数ｆｓｒが、所定の値（信号周波数ＦＲ）に一致するように、その厚みを調整しておく。同様に、受波素子１３を得る、分極後の大型の圧電素子における厚み方向の反共振周波数ｆｒａが、所定の値（信号周波数ＦＲ）に一致するように、その厚みを調整しておく。これにより、得られた送波素子１２の共振周波数ｆｓｒと、受波素子１３の反共振周波数ｆｒａを、何れも、信号周波数ＦＲに等しくできる。
なお、送波素子１２を構成する圧電セラミックスの材質と、受波素子１３を構成する圧電セラミックスの材質とを、同じとしても良いし、互いに異なる材質としても良い。 However, the thickness is adjusted so that the resonance frequency fsr in the thickness direction of the large piezoelectric element after polarization that obtains the transmission element 12 matches a predetermined value (signal frequency FR). Similarly, the thickness is adjusted so that the anti-resonance frequency fr in the thickness direction of the large piezoelectric element after polarization that obtains the wave receiving element 13 matches a predetermined value (signal frequency FR). As a result, the obtained resonant frequency fsr of the transmitting element 12 and the anti-resonant frequency fr of the receiving element 13 can both be equal to the signal frequency FR.
The material of the piezoelectric ceramic constituting the wave transmitting element 12 and the material of the piezoelectric ceramic constituting the wave receiving element 13 may be the same or different from each other.

（実施形態２）
次いで、第２の実施形態について、図４，図５を参照して説明する。
なお、本実施形態２では、前述の実施形態１で用いたのと同じ送波素子１２及び受波素子１３を用いているが、その配置が異なる。
そこで、異なる部分を中心に説明し、同様な部分については、記載を省略あるいは簡略化する。 (Embodiment 2)
Next, a second embodiment will be described with reference to FIGS.
In the second embodiment, the same transmitting element 12 and receiving element 13 as those used in the first embodiment are used, but their arrangements are different.
Therefore, different parts will be mainly described, and description of similar parts will be omitted or simplified.

実施形態１の超音波センサ１０（図１，図２参照）では、送波素子１２及び受波素子１３は、互いに別に集め、送波素子１２同士、及び受波素子１３同士で密集して配置した。
これに対し、本実施形態２の超音波センサ２０では、送波素子１２と受波素子１３とを、混在して配置した。具体的には、図４，図５に示すように、平面視、正方形状の振動板２１の固着面２１Ａの中央に、１６ヶの受波素子１３を４段４列の格子状に配置した。さらに、その周囲を、環状に配置した合計２０ヶの送波素子１２で囲んだ。これにより、合計３６ヶの素子１２，１３を、６段６列の格子状に配置した。 In the ultrasonic sensor 10 according to the first embodiment (see FIGS. 1 and 2), the transmitting elements 12 and the receiving elements 13 are collected separately from each other, and are arranged densely between the transmitting elements 12 and the receiving elements 13. did.
On the other hand, in the ultrasonic sensor 20 of the second embodiment, the transmitting element 12 and the receiving element 13 are mixedly arranged. Specifically, as shown in FIG. 4 and FIG. 5, 16 receiving elements 13 are arranged in a lattice form of 4 rows and 4 rows in the center of the fixed surface 21 A of the diaphragm 21 in a plan view in plan view. . Further, the periphery thereof was surrounded by a total of 20 transmitting elements 12 arranged in a ring shape. As a result, a total of 36 elements 12 and 13 were arranged in a grid of 6 stages and 6 rows.

送波素子１２（送波側電極１２Ｃ）は、実施形態１と同様、図示しない接着剤で振動板２１の固着面２１Ａに接着されて、振動板２１に固着されている。これと共に、送波側電極１２Ｃが、振動板２１に導通している。また、受波素子１３（受波側電極１３Ｃ）も、図示しない接着剤で振動板２１の固着面２１Ａに接着されて、振動板２１に固着されている。これと共に、受波側電極１３Ｃが、振動板２１に導通している。 Similarly to the first embodiment, the wave transmitting element 12 (the wave transmitting side electrode 12C) is bonded to the fixing surface 21A of the diaphragm 21 with an adhesive (not shown) and fixed to the diaphragm 21. At the same time, the transmission-side electrode 12 C is electrically connected to the diaphragm 21. The wave receiving element 13 (the wave receiving side electrode 13C) is also bonded to the vibration plate 21 by being bonded to the fixing surface 21A of the vibration plate 21 with an adhesive (not shown). At the same time, the receiving-side electrode 13 C is electrically connected to the diaphragm 21.

さらに、実施形態１と同様、各送波素子１２の裏面側電極１２Ｄ同士は、送波側リード線２５で並列にハンダ付けにより接続され、外部に取り出されている。同様に、各受波素子１３の裏面側電極１３Ｄ同士も、受波側リード線２６で並列にハンダ付けにより接続され、外部に取り出されている。さらに、振動板２１の固着面２１Ａにも、共通リード線２７がハンダ付けされている（図５参照）。
また、各素子１２，１３の間には、実施形態１と同様、介在樹脂材１４が充填されている。
なお、図５においては、送波素子１２と受波素子１３とを区別するため、送波素子１２にハッチングを施して表示している。 Further, similarly to the first embodiment, the back surface side electrodes 12D of the transmission elements 12 are connected to each other by soldering in parallel on the transmission side lead wires 25 and taken out to the outside. Similarly, the back surface side electrodes 13D of the wave receiving elements 13 are also connected to the wave receiving side lead wires 26 in parallel by soldering and taken out to the outside. Further, the common lead wire 27 is also soldered to the fixing surface 21A of the diaphragm 21 (see FIG. 5).
Further, the intervening resin material 14 is filled between the elements 12 and 13 as in the first embodiment.
In FIG. 5, in order to distinguish between the transmitting element 12 and the receiving element 13, the transmitting element 12 is hatched and displayed.

この超音波センサ２０では、リング状に配置した複数の送波素子１２で超音波（送波超音波ＵＳＳ）を発生させ放射する。その一方、反射して戻った超音波（受波超音波ＵＳＲ）を、送波素子１２の内側に集められた複数の受波素子１３で受波できる。このため、放射される送波超音波ＵＳＳの放射方向と、受波できる受波超音波ＵＳＲの方向とにずれが無く、自身が放射した送波超音波ＵＳＳが反射して戻った受波超音波ＵＳＲを、効果的に受波することができる。 In this ultrasonic sensor 20, an ultrasonic wave (transmitted ultrasonic wave USS) is generated and radiated by a plurality of transmitting elements 12 arranged in a ring shape. On the other hand, the reflected ultrasonic waves (received ultrasonic waves USR) can be received by a plurality of receiving elements 13 collected inside the transmitting element 12. For this reason, there is no deviation between the radiation direction of the transmitted ultrasonic wave USS and the direction of the received ultrasonic wave USR that can be received, and the received ultrasonic wave USS that is radiated by the reflected ultrasonic wave USS is reflected and returned. The sound wave USR can be received effectively.

以上において、本発明を実施形態１，２に即して説明したが、本発明は上記実施形態に限定されるものではなく、その要旨を逸脱しない範囲で、適宜変更して適用できることはいうまでもない。
例えば、実施形態１，２では、送波素子１２及び受波素子１３を、平面視したとき、同寸の正方形となる、正四角柱の形状としたが、同寸、同形状としなくともよい。
また、各実施形態では、超音波センサ１０，２０を、振動板１１（２１）、送波素子１２、受波素子１３、介在樹脂材１４、及びリード線１５〜１７（２５〜２７）からなるものとしたが、送波素子１２，受波素子１３等を、ケースで包囲する、さらには気密に包囲するなど、他の形態とすることもできる。
また、各実施形態では、振動板１１（超音波伝達部材）の材質を、金属としたが、樹脂、ゴム等を選択することもできる。 In the above, the present invention has been described with reference to the first and second embodiments. However, the present invention is not limited to the above-described embodiments, and it can be applied as appropriate without departing from the scope of the present invention. Nor.
For example, in the first and second embodiments, the transmitting element 12 and the receiving element 13 are formed in the shape of a regular quadrangular prism that is a square having the same size when viewed in plan, but the same size and the same shape may not be used.
In each embodiment, the ultrasonic sensors 10 and 20 include the diaphragm 11 (21), the wave transmitting element 12, the wave receiving element 13, the intervening resin material 14, and the lead wires 15 to 17 (25 to 27). However, the transmitting element 12, the receiving element 13, and the like may be surrounded by a case, or may be in other forms such as airtightly.
Moreover, in each embodiment, although the material of the diaphragm 11 (ultrasonic transmission member) was metal, resin, rubber | gum, etc. can also be selected.

１０，２０超音波センサ（超音波送受波装置）
１１，２１振動板（超音波伝達部材）
１１Ａ，２１Ａ固着面
１１Ｂ，２１Ｂ超音波送受波面
１２送波素子（送波用圧電素子）
１２Ａ超音波送波面
１２Ｂ裏面
１２Ｃ送波側電極
１２Ｈ（送波素子の）厚み方向寸法
１２Ｊ（送波素子の）径方向寸法
１３受波素子（受波用圧電素子）
１３Ａ超音波受波面
１３Ｂ裏面
１３Ｃ受波側電極
１３Ｄ裏面側電極
１３Ｈ（受波素子の）厚み方向寸法
１３Ｊ（受波素子の）径方向寸法
１４介在樹脂材
１５，２５送波側リード線
１６，２６受波側リード線
１７，２７共通リード線
ＵＳＳ送波超音波
ＵＳＲ受波超音波
ＴＤ厚み方向
ＤＤ径方向
ＦＲ信号周波数
ＭＤ媒体
ｆｓｒ（送波素子の厚み方向振動の）共振周波数
ｆｒａ（受波素子の厚み方向振動の）反共振周波数 10,20 Ultrasonic sensor (Ultrasonic transducer)
11, 21 Diaphragm (Ultrasonic transmission member)
11A, 21A Adhering surfaces 11B, 21B Ultrasonic wave transmitting / receiving surface 12 Transmitting element (piezoelectric element for transmitting)
12A Ultrasonic wave transmitting surface 12B Back surface 12C Transmitting side electrode 12H Thickness direction dimension 12J (transmitting element) Radial direction dimension 13 Receiving element (receiving piezoelectric element)
13A Ultrasonic wave receiving surface 13B Back surface 13C Wave receiving side electrode 13D Back surface side electrode 13H Thickness direction dimension 13J (receiving element) Radial direction dimension 14 Intervening resin material 15, 25 Transmitting side lead wire 16, 26 Receiving-side lead wires 17 and 27 Common lead wire USS Transmitting ultrasonic wave USR Receiving ultrasonic wave TD Thickness direction DD Radial direction FR Signal frequency MD Medium fsr Resonance frequency fr (Receiving vibration in thickness direction of transmitting element) Anti-resonance frequency (in the thickness direction of the element)

Claims

A plurality of piezoelectric elements for transmission;
A plurality of receiving piezoelectric elements;
A fixing surface to which the transmitting piezoelectric element and the receiving piezoelectric element are fixed; and
Has an ultrasonic wave transmitting / receiving surface for transmitting and receiving ultrasonic waves,
The ultrasonic wave generated by the piezoelectric element for transmission is transmitted from the fixed surface to the ultrasonic transmission / reception surface and radiated from the ultrasonic transmission / reception surface,
An ultrasonic transmission / reception device comprising: an ultrasonic transmission member that transmits ultrasonic waves that have reached the ultrasonic transmission / reception surface from the ultrasonic transmission / reception surface to the piezoelectric element for reception through the fixing surface,
The plurality of piezoelectric elements for transmission are
Each of the dimensions in the thickness direction orthogonal to the fixing surface is larger than the radial dimension parallel to the fixing surface,
In the thickness direction, has a characteristic of mechanical resonance at a predetermined frequency,
Electrically connected to each other in parallel,
The plurality of receiving piezoelectric elements are:
Each of the dimensions in the thickness direction is larger than the dimensions in the radial direction,
In the thickness direction, has a characteristic of mechanically anti-resonance at the predetermined frequency,
An ultrasonic transducer that is electrically connected to each other in parallel.

The ultrasonic transmission / reception device according to claim 1,
An ultrasonic wave transmitting / receiving apparatus in which the plurality of receiving piezoelectric elements are arranged inside and the plurality of transmitting piezoelectric elements are arranged so as to surround an outer periphery of the receiving piezoelectric element.