JPS6133515B2 - - Google Patents
Info
- Publication number
- JPS6133515B2 JPS6133515B2 JP6980A JP6980A JPS6133515B2 JP S6133515 B2 JPS6133515 B2 JP S6133515B2 JP 6980 A JP6980 A JP 6980A JP 6980 A JP6980 A JP 6980A JP S6133515 B2 JPS6133515 B2 JP S6133515B2
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- interdigital
- liquid
- transducer
- substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000007788 liquid Substances 0.000 claims description 21
- 239000000758 substrate Substances 0.000 claims description 14
- 238000005191 phase separation Methods 0.000 claims 1
- 235000019687 Lamb Nutrition 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 3
- 229910013641 LiNbO 3 Inorganic materials 0.000 description 2
- 230000010363 phase shift Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000002604 ultrasonography Methods 0.000 description 2
- NCGICGYLBXGBGN-UHFFFAOYSA-N 3-morpholin-4-yl-1-oxa-3-azonia-2-azanidacyclopent-3-en-5-imine;hydrochloride Chemical compound Cl.[N-]1OC(=N)C=[N+]1N1CCOCC1 NCGICGYLBXGBGN-UHFFFAOYSA-N 0.000 description 1
- 244000126211 Hericium coralloides Species 0.000 description 1
- 230000002730 additional effect Effects 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002594 fluoroscopy Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 239000011344 liquid material Substances 0.000 description 1
- 238000009659 non-destructive testing Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012285 ultrasound imaging Methods 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
- H03H9/14502—Surface acoustic wave [SAW] transducers for a particular purpose
- H03H9/14505—Unidirectional SAW transducers
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Transducers For Ultrasonic Waves (AREA)
Description
【発明の詳細な説明】
本発明は一般にトランスデユーサに関し、特に
液状体中に一方向の超音波を発生するごとき一方
向性トランスデユーサに関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to transducers, and more particularly to unidirectional transducers, such as those that generate unidirectional ultrasonic waves in a liquid.
ところで光学的に不透明な媒質でも、音響的に
透明でありさえすれば、X線による透視と同様に
音波による透視像の観測が可能であり、このよう
な光学的不透明体の超音波による撮像は医療診
断、非破壊検査、海底の模様の観測等の分野への
応用が可能である。この種の超音波装置に用いら
れる超音波発生用のトランスデユーサとしては従
来、音響位相板を用いるもの、環状アレイを用い
るもの、音響レンズを用いるもの、光−音響トラ
ンスデユーサを用いるもの、などが提案されてい
る。しかしながら超音波撮像に必要な音波の集束
という点でなお改善の余地があるのが実情であ
る。 By the way, even if an optically opaque medium is acoustically transparent, it is possible to observe a fluoroscopic image using sound waves in the same way as fluoroscopy using X-rays. It can be applied to fields such as medical diagnosis, non-destructive testing, and observation of ocean floor patterns. Conventional transducers for generating ultrasonic waves used in this type of ultrasonic device include those using an acoustic phase plate, those using an annular array, those using an acoustic lens, and those using a photo-acoustic transducer. etc. have been proposed. However, the reality is that there is still room for improvement in terms of focusing the sound waves necessary for ultrasound imaging.
従つて本発明者は従来の技術の上記欠点を改善
するものとして先に特願昭53−100929を提案し
た。これは、ラム波が励起されるに足る厚さをも
つ圧電性基板の一面に、電極指の間隔に特別の関
係をもたせすだれ状電極を設け、他面を液体に接
した状態で上記すだれ状電極に交流電圧を印加す
ることによつて他面から液体中に収束性のよい超
音波ビームを発射するものである。 Therefore, the present inventor previously proposed Japanese Patent Application No. 100929/1983 as a method for improving the above-mentioned drawbacks of the prior art. This method involves installing interdigital electrodes with a special relationship between the electrode fingers on one side of a piezoelectric substrate that is thick enough to excite Lamb waves, and placing the interdigital electrodes in contact with a liquid with the other side in contact with the liquid. By applying an alternating current voltage to the electrodes, a highly convergent ultrasonic beam is emitted into the liquid from the other side.
しかしながら、上記技術では超音波ビームが圧
電性基板の垂線に対して+θ方向と−θ方向に2
波発射され、用途によつてはこれが不要信号を発
生する原因となるおそれがある。 However, in the above technology, the ultrasonic beam is oriented 2 times in +θ direction and -θ direction with respect to the perpendicular line of the piezoelectric substrate.
Depending on the application, this may cause unwanted signals to be generated.
従つて本発明は従来の技術の上記欠点を改善す
るもので、その目的は集束性のよい一方向性トラ
ンスデユーサを提供することにある。この目的を
達成するための本発明の特徴は、すだれ状電極の
電極指の間隔と印加電圧の位相との間に特別の関
係をもたせることにより超音波ビームの一方向性
を実現すると共に、該超音波ビームを集束させる
ため更に電極指の間隔に特別の関係をもたせるこ
とにある。以下図面により実施例を説明する。 SUMMARY OF THE INVENTION Accordingly, the present invention aims to improve the above-mentioned drawbacks of the prior art, and its object is to provide a unidirectional transducer with good focusability. A feature of the present invention for achieving this object is to realize the unidirectionality of the ultrasonic beam by creating a special relationship between the spacing between the electrode fingers of the interdigital electrodes and the phase of the applied voltage. In order to focus the ultrasonic beam, there is also a special relationship to the spacing between the electrode fingers. Examples will be described below with reference to the drawings.
第1図は本発明による一方向性トランスデユー
サの構造例を示し、1は圧電性基板でその厚さは
該基板におけるラム波の波長λと同程度又はそれ
以下とする。2および3はくしの歯状の電極指が
交互にインターデイジタルに構成される1対のす
だれ状電極で、上記圧電性基板1の一つの面に設
けられる。該すだれ状電極2および3は第2図に
示すごとく、その各電極指の隣接する電極指との
間の距離が左右非対称となるごとく構成される。
4はすだれ状電極2および3に対向して圧電性基
板1の他面に設けられる平面電極、5は該平面電
極4に接する液状体である。 FIG. 1 shows an example of the structure of a unidirectional transducer according to the present invention, in which numeral 1 denotes a piezoelectric substrate whose thickness is approximately equal to or less than the wavelength λ of the Lamb wave in the substrate. Reference numerals 2 and 3 designate a pair of interdigital interdigital electrodes in which comb-tooth electrode fingers are arranged alternately in an interdigital manner, and are provided on one surface of the piezoelectric substrate 1. As shown in FIG. 2, the interdigital electrodes 2 and 3 are constructed so that the distance between each electrode finger and the adjacent electrode finger is asymmetrical.
4 is a planar electrode provided on the other surface of the piezoelectric substrate 1 facing the interdigital electrodes 2 and 3; and 5 is a liquid in contact with the planar electrode 4.
以上のごとき構造で、移相器(図示しない)に
より単相入力から位相の異なる2つの電圧をつく
り出し、これらをすだれ状電極2および3に印加
することによりトランスデユーサを駆動すれば、
平面電極4を有する面から次式を満足する縦波音
波の放射が起り、音波は液体中に放射される。 With the above structure, if two voltages with different phases are generated from a single-phase input using a phase shifter (not shown), and the transducer is driven by applying these to the interdigital electrodes 2 and 3, the transducer is driven.
Emission of longitudinal sound waves satisfying the following equation occurs from the surface having the plane electrode 4, and the sound waves are emitted into the liquid.
sinθ=VW/VL (1)
ここでθは放射される音波の方向、VWは液体
中での音波の速度、VLは圧電体上を伝播するラ
ム波の速度である。sinθ=V W /V L (1) Here, θ is the direction of the emitted sound wave, V W is the speed of the sound wave in the liquid, and V L is the speed of the Lamb wave propagating on the piezoelectric body.
ラム波はレーリー波とは異なつて、波が伝搬す
る媒体の表裏両面に変位が存在し、しかも対称モ
ードの場合には、その変位の特性が同じである。
したがつて、この特性を考慮すると、すだれ状電
極を有する面と、その反対側の面とで、変位の状
況が同じこととなり、すだれ状電極を含む面を液
体に接することなく、反対側の面(平面状電極を
有する面)を液体に接することによつて、液体中
への音波の効率よい放射を実現できることとな
る。さらにこのタイプのトランスデユーサ部に到
達した音波を効率よく電気信号に変換することも
可能であり、その場合にも上述の(1)式満足する方
向からの音波に対して感度が最大となる。 Lamb waves differ from Rayleigh waves in that displacement exists on both the front and back sides of the medium in which the waves propagate, and in the case of symmetric modes, the displacement characteristics are the same.
Therefore, considering this characteristic, the displacement situation is the same on the surface with the interdigital electrode and the surface on the opposite side, and the surface containing the interdigital electrode can be moved to the opposite side without contacting the liquid. By bringing the surface (the surface having the planar electrode) into contact with the liquid, efficient radiation of sound waves into the liquid can be realized. Furthermore, it is also possible to efficiently convert the sound waves that reach this type of transducer into electrical signals, and in that case, the sensitivity is maximized for sound waves from the direction that satisfies equation (1) above. .
ところで、本発明と異なり圧電性基板上に設け
るすだれ状電極の周期が等間隔の場合には、すだ
れ状電極の各セクシヨンから放射される音波は、
(1)式との関係において、次式を満足する方向に平
行な音波ビームとして放射される。 By the way, unlike the present invention, when the periods of the interdigital electrodes provided on the piezoelectric substrate are equal intervals, the sound waves emitted from each section of the interdigital electrodes are as follows:
In relation to equation (1), it is emitted as a parallel sound beam in a direction that satisfies the following equation.
λ=sin-1VW/f・d (2)
ここでfはトランスデユーサに印加される電気
信号のキヤリア周波数、dはすだれ状電極の電極
周期である。λ=sin −1 V W /f·d (2) where f is the carrier frequency of the electrical signal applied to the transducer, and d is the electrode period of the interdigital electrode.
この場合には、超音波ビームは第3図に示すご
とく+θ方向と−θ方向に2波発射されることに
なるので、その用途によつては適当でないことを
前述した。一方、印加する交流電圧が三相の場合
においては、以下に述べるごとくすだれ状電極の
電極指の間隔と印加電圧の位相との間に特別の関
係をもたせることにより、液状体中に放射される
超音波ビームの一方向性が実現される。 In this case, as shown in FIG. 3, two waves of ultrasonic beams are emitted in the +θ direction and in the −θ direction, so it was mentioned earlier that this is not appropriate depending on the application. On the other hand, when the applied AC voltage is three-phase, the radiation into the liquid is created by creating a special relationship between the spacing between the electrode fingers of the interdigital electrodes and the phase of the applied voltage, as described below. Unidirectionality of the ultrasound beam is achieved.
すなわち、第4図に示すごとくすだれ状電極の
電極周期Pに対して、電極指の中心から隣接する
電極指の中心までの狭い方の距離をxPとすれ
ば、電極構成による移相距離が2πxであらわさ
れるので、すだれ状電極の夫々に印加する電圧の
位相差を2πyとし、これらの和が180゜となる
ごとくすること、すなわち(3)式を満足するごとく
すれば、超音波ビームが液状体中の一方向に平行
ビームとして放射される。 In other words, if xP is the narrower distance from the center of an electrode finger to the center of an adjacent electrode finger with respect to the electrode period P of the interdigital electrode as shown in Fig. 4, then the phase shift distance due to the electrode configuration is 2πx. Therefore, by setting the phase difference of the voltages applied to each of the interdigital electrodes to be 2πy and making the sum of these 180°, that is, satisfying equation (3), the ultrasonic beam will be in the liquid state. It is emitted as a parallel beam in one direction throughout the body.
x+y=1/2 (3)
次に、上述した平行な超音波ビームを集束する
ための電極構成を、第4図に基づいて説明する。
周波数fの音波のある液体中での波長λfと、ビ
ームの最大出力の方向(角度θ)との関係は次式
により定まり、この式は本発明者による実験結果
とよく一致する。x+y=1/2 (3) Next, the electrode configuration for focusing the above-mentioned parallel ultrasound beams will be explained based on FIG. 4.
The relationship between the wavelength λ f of a sound wave of frequency f in a liquid and the direction of maximum beam output (angle θ) is determined by the following equation, and this equation agrees well with the experimental results by the inventor.
sinθ=λf/P (4)
従つて第3図において、各電極から発生する音
波が点Qに集束するためには(つまり各点で発生
する音波が点Qを通りかつ同相となる条件)次式
の条件が満足されねばならない。sinθ=λ f /P (4) Therefore, in Fig. 3, in order for the sound waves generated from each electrode to be focused on point Q (that is, the conditions for the sound waves generated at each point to pass through point Q and be in phase) The following condition must be satisfied.
nが正の整数の場合
X2o=(R2 0sin2θ0+2nλfR0+n2λf 2)1/2
X2o+1=〔R2 0sin2θ0+2(2n+1)xλfR0+(2n+1)2x2λf 2〕1/2
nが負の整数の場合
X2o=(R2 0sin2θ0+2nλfR0+n2λf 2)1/2
X2o-1=〔R2 0sin2θ0+2(2n+1)(1−x)λfR0+(2n+1)2(1−x)2λf 2〕1/2 (5)
ここで、R0は零番目の電極からビームの収束
点までの距離、X2o、X2o+1は原点(0)と当該
電極との間の水平距離である。 When n is a positive integer , X 2o = (R 2 0 sin 2 θ 0 + 2nλ f R 0 + n 2 λ f 2 ) 1/2 R 0 + (2n+1) 2 x 2 λ f 2 ] 1/2 When n is a negative integer, X 2o = (R 2 0 sin 2 θ 0 +2nλ f R 0 +n 2 λ f 2 ) 1/2 X 2o- 1 = [R 2 0 sin 2 θ 0 +2(2n+1)(1-x)λ f R 0 +(2n+1) 2 (1-x) 2 λ f 2 ] 1/2 (5) Here, R 0 is The distance from the zeroth electrode to the beam convergence point, X 2o , X 2o+1 is the horizontal distance between the origin (0) and the electrode.
一方向にのみ平行ビームを放射する場合には、
本発明によるすだれ状電極は第2図に示すごとき
構成の電極で十分であり、従つて本発明では電極
構造が非常に簡略化される。 When emitting a parallel beam in only one direction,
As the interdigital interdigital electrode according to the present invention, an electrode having the structure shown in FIG. 2 is sufficient, and therefore, the electrode structure is greatly simplified in the present invention.
以上の説明で、電極の材料としては例えばCr
とAuを組合せたのが強度が強く良好であり、電
極は蒸着、スパツタ等の公知の技術により圧電体
表面に形成される圧電性物質としてはLiNbO3、
水晶、Bi12GeO20、PZT系磁器(例えば東京電気
化学工業(株)製91A材)などが可能である。 In the above explanation, for example, Cr
A combination of LiNbO 3 and Au has good strength and good strength, and the electrode is formed on the surface of the piezoelectric material by known techniques such as vapor deposition and sputtering. LiNbO 3 ,
Possible materials include crystal, Bi 12 GeO 20 , and PZT-based porcelain (for example, 91A material manufactured by Tokyo Denki Kagaku Kogyo Co., Ltd.).
実験例:圧電性基板として分極軸が厚さ方向の
東京電気化学工業株式会社(TDK)製の圧電磁
器91A材(長さ70mm、幅20mm、厚さ0.2mm、零次
対称モードラム波の速度3500m/sec)を用い、該
基板の一面にすだれ状電極を他面に平面電極を設
け、すだれ状電極の電極構成における移相距離x
が1/4で、トランスデユーサから30cmの場所に
2.5MHzの音波を収束させるように設計した。な
お、すだれ状電極の電極対数は50である。 Experimental example: Piezoelectric ceramic 91A material manufactured by Tokyo Denki Kagaku Kogyo Co., Ltd. (TDK) with the polarization axis in the thickness direction as a piezoelectric substrate (length 70 mm, width 20 mm, thickness 0.2 mm, zero-order symmetric moderam wave velocity) 3500 m/sec), a transducer-shaped electrode is provided on one side of the substrate, and a flat electrode is provided on the other surface, and the phase shift distance x in the electrode configuration of the transducer-shaped electrode is
is 1/4 and 30cm from the transducer.
It was designed to converge 2.5MHz sound waves. Note that the number of electrode pairs of the interdigital electrodes is 50.
以上のごとき位様のトランスデユーサを、すだ
れ状電極が液体に接しないように水タンクの中に
マウントし、平面電極を有する面から液体中に放
射される音波の分布をポイント・プルーブ(圧電
トランスデユーサ)で測定した。第5図は測定結
果を示し、音波ビームの集束点までの距離が設計
値に近いことがわかる。ここにビーム幅は、エネ
ルギーが中心より3dB低下するビーム幅を示して
いる。なお、この場合にトランスデユーサに印加
する2つの電気信号の位相差は90゜(y=1/4に相
当する)で、x+y=1/2の関係を満足する。 The transducer as described above is mounted in a water tank so that the interdigital electrodes do not come into contact with the liquid, and the distribution of sound waves emitted into the liquid from the surface with the flat electrodes is measured using point probes (piezoelectric transducer). FIG. 5 shows the measurement results, and it can be seen that the distance to the focal point of the acoustic beam is close to the designed value. The beam width here indicates the beam width at which the energy is 3 dB lower than the center. In this case, the phase difference between the two electrical signals applied to the transducer is 90° (corresponding to y=1/4), which satisfies the relationship x+y=1/2.
第6図は一方向特性の測定結果で、20dBの方
向性が確認された。第6図の測定結果は位相距離
xが1/4の場合であるが、x=1/3の場合にも実験的
に同様のことが確認された。この場合には60゜の
移相器(y=1/6)を用いた。 Figure 6 shows the measurement results of the unidirectional characteristics, and a directionality of 20 dB was confirmed. The measurement results shown in FIG. 6 are for the case where the phase distance x is 1/4, but the same thing was experimentally confirmed when x=1/3. In this case, a 60° phase shifter (y=1/6) was used.
第7図は前述した位相距離xが1/4のトランス
デユーサにおける集束点の方向とキヤリヤ周波数
の関係を測定したもので、キヤリア周波数の変化
により集束点の位置が可変となることが理解され
る。 Figure 7 shows the measurement of the relationship between the direction of the focal point and the carrier frequency in the transducer with a phase distance x of 1/4, as described above, and it is understood that the position of the focal point changes as the carrier frequency changes. Ru.
以上説明したごとく本発明によれば、集束性の
よい一方向性の超音波ビームを液体中に発射する
ことができ、更に不加的な効果として、すだれ状
電極を含む面が液体と直接接触することがないの
ですだれ状電極の機械的および化学的保護の必要
性がないと共に、平板状構造でありビームの集束
のための球面を必要とせず、また、多層技術を用
いることなしに三相構成が可能で、1つの面上に
三相構成をとる場合よりも構造が簡単になる。 As explained above, according to the present invention, it is possible to emit a highly focused unidirectional ultrasonic beam into a liquid, and as an additional effect, the surface including the interdigital electrode comes into direct contact with the liquid. There is no need for mechanical or chemical protection of interdigital electrodes, and the planar structure eliminates the need for spherical surfaces for beam focusing, and the three-layer structure does not require the use of multilayer techniques. Phase configuration is possible, and the structure is simpler than a three-phase configuration on one surface.
本発明の応用は、単に撮像用に限定されるもの
ではなく、音波ビームを集束させる必要のある用
途に一般に適用可能であり、例えば、ビームを液
体と空気の境界面に集束させて、液体の霧化を行
なわせることが出来る。 Applications of the invention are not limited solely to imaging, but are generally applicable to applications where a beam of acoustic waves needs to be focused, for example to focus the beam onto a liquid-air interface to Atomization can be performed.
第1図は本発明による超音波トランスデユーサ
の構造例、第2図はすだれ状電極の構造例、第3
図は従来のトランスデユーサの動作説明図、第4
図は本発明の動作説明図、第5図、第6図および
第7図は実験結果の1例を示す図である。
1;圧電性基板、2,3;すだれ状電極、4;
平面電極、5;液状体。
FIG. 1 shows an example of the structure of an ultrasonic transducer according to the present invention, FIG. 2 shows an example of the structure of an interdigital electrode, and FIG.
The figure is an explanatory diagram of the operation of a conventional transducer.
The figure is an explanatory diagram of the operation of the present invention, and FIGS. 5, 6, and 7 are diagrams showing examples of experimental results. 1; piezoelectric substrate, 2, 3; interdigital electrode, 4;
Planar electrode, 5; liquid material.
Claims (1)
板における超音波の波長)、該基板のひとつの面
にもうけられる1対のインターデイジタルに構成
されるすだれ状電極と、該基板の前記面と対向す
る面にもうけられ前記すだれ状電極と対向する平
面電極とを有し、該平面電極が液状体に接する状
態で前記すだれ状電極および平面電極に交流電圧
を印加することにより液状体中に超音波を発生す
るトランスデユーサにおいて、前記すだれ状電極
の電極指を、各電極指と隣接する電極指との間隔
が左右非対称となるごとく構成し、電極指間隔の
狭い方の位相的隔たりとの和が180゜となるごと
き位相差をもつ電気信号を印加することによつて
液状体中の一方向に超音波を発生することを特徴
とする一方向性トランスデユーサ。 2 前記すだれ状電極の各電極指の間隔が、 nが正の整数の場合 X2o=(R2 0sin2θ0+2nλfR0+n2λf 2)1/2 X2o+1=〔R2 0sin2θ0+2(2n+1)xλfR0+(2n+1)2x2λf 2〕1/2 nが負の整数の場合 X2o=(R2 0sin2θ0+2nλfR0+n2λf 2)1/2 X2o+1=〔R2 0sin2θ0+2(2n+1)(1−x)λfR0+(2n+1)2(1−x)2λf 2〕1/2 ここでλfは周波数fの音波の液状体中の波
長、R0は零番目の電極からビームの集束点まで
の距離、θ0は零番目の電極からのビームの方
向、2πxは狭い方の電極指間隔の位相的隔たり
を満足するごとく構成されることを特徴とする特
許請求の範囲第1項の一方向性トランスデユー
サ。[Claims] 1. A piezoelectric substrate having a thickness of approximately λ or less (λ is the wavelength of ultrasonic waves in the substrate), and a pair of interdigital interdigital blinds formed on one surface of the substrate. an electrode, and a planar electrode provided on a surface opposite to the surface of the substrate and facing the interdigital electrode, and applying an alternating current voltage to the interdigital electrode and the planar electrode in a state where the planar electrode is in contact with the liquid. In a transducer that generates ultrasonic waves in a liquid by applying an ultrasonic wave, the electrode fingers of the interdigital electrode are configured such that the distance between each electrode finger and the adjacent electrode finger is asymmetrical, and the electrode finger spacing is A unidirectional transformer characterized in that an ultrasonic wave is generated in one direction in a liquid by applying an electric signal having a phase difference such that the sum of the phase difference and the narrower phase difference is 180°. Duusa. 2 The spacing between the electrode fingers of the interdigital electrode is as follows: When n is a positive integer , R 2 0 sin 2 θ 0 +2 ( 2n + 1 )xλ f R 0 +(2n+1) 2 x 2 λ f 2 ] 1/2 If n is a negative integer, then 0 + n 2 λ f 2 ) 1/2 _ _ _ _ _ _ _ ] 1/2 where λ f is the wavelength of the sound wave with frequency f in the liquid, R 0 is the distance from the zeroth electrode to the beam focal point, θ 0 is the direction of the beam from the zeroth electrode, and 2πx 2. The unidirectional transducer according to claim 1, wherein the unidirectional transducer is constructed so as to satisfy the phase separation of the narrower electrode finger spacing.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6980A JPS5698099A (en) | 1980-01-07 | 1980-01-07 | One-way transducer |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6980A JPS5698099A (en) | 1980-01-07 | 1980-01-07 | One-way transducer |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS5698099A JPS5698099A (en) | 1981-08-07 |
JPS6133515B2 true JPS6133515B2 (en) | 1986-08-02 |
Family
ID=11463887
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP6980A Granted JPS5698099A (en) | 1980-01-07 | 1980-01-07 | One-way transducer |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5698099A (en) |
-
1980
- 1980-01-07 JP JP6980A patent/JPS5698099A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS5698099A (en) | 1981-08-07 |
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