JPS643119B2 - - Google Patents
Info
- Publication number
- JPS643119B2 JPS643119B2 JP4494683A JP4494683A JPS643119B2 JP S643119 B2 JPS643119 B2 JP S643119B2 JP 4494683 A JP4494683 A JP 4494683A JP 4494683 A JP4494683 A JP 4494683A JP S643119 B2 JPS643119 B2 JP S643119B2
- Authority
- JP
- Japan
- Prior art keywords
- vibrator
- thermally expandable
- matching layer
- acoustic impedance
- composite material
- 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
- 239000000919 ceramic Substances 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 6
- 230000005855 radiation Effects 0.000 claims description 6
- 239000004005 microsphere Substances 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 2
- 229920003002 synthetic resin Polymers 0.000 claims description 2
- 239000000057 synthetic resin Substances 0.000 claims description 2
- 239000010409 thin film Substances 0.000 claims 1
- 239000002131 composite material Substances 0.000 description 23
- 238000010438 heat treatment Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 8
- 229920006332 epoxy adhesive Polymers 0.000 description 4
- 239000013464 silicone adhesive Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229920002379 silicone rubber Polymers 0.000 description 2
- 239000004945 silicone rubber Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Transducers For Ultrasonic Waves (AREA)
- Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、距離計測装置用超音波センサなどに
用いられる超音波トランスジユーサに関する。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasonic transducer used in an ultrasonic sensor for a distance measuring device, etc.
従来例の構成とその問題点
従来、圧電セラミツク振動子又は磁歪振動子を
空中用超音波トランスジユーサとして用いる場
合、これらの振動子は固有音響インピーダンスが
空気と比べて大きい固有音響インピーダンスを有
するので、振動子と超音波伝搬媒体としての空気
との固有音響インピーダンスの不整合を改善する
ために、第１図に示すようにエポキシ系接着剤あ
るいはシリコーン系接着剤などの母材中に、直径
数十〜数百μm以下のガラス、カーボン等の微小
中空球（以下マイクロスフエアと呼ぶ。図示せ
ず）を充てんした複合材料から成る薄層１、ある
いはシリコーン系ゴムなどから成る薄層１が振動
子２の音波放射面３に接着され整合層として用い
られていたが、振動子２と空気との整合条件を十
分に満足するには至らなかつた。Conventional configurations and their problems Conventionally, when piezoelectric ceramic vibrators or magnetostrictive vibrators are used as airborne ultrasonic transducers, these vibrators have a large natural acoustic impedance compared to air. In order to improve the mismatch in the characteristic acoustic impedance between the transducer and air as the ultrasonic propagation medium, as shown in Fig. A thin layer 1 made of a composite material filled with microscopic hollow spheres (hereinafter referred to as microspheres, not shown) made of glass, carbon, etc. of 10 to several hundred μm or less, or a thin layer 1 made of silicone rubber, etc. vibrates. Although it was bonded to the sound wave emitting surface 3 of the vibrator 2 and used as a matching layer, it did not fully satisfy the matching conditions between the vibrator 2 and the air.
即ち、圧電セラミツク振動子２の音速v1は約
3500m/s、密度ρ1は約8000Kg/m3の値であり、従
つてそれらの積で表わされる固有音響インピーダ
ンスz1は、大体３×107N・Ｓ／m3程度の値とな
るが、一方空気の常温における固有音響インピー
ダンスz2は約400N・Ｓ／m3であるので、一層整
合層を用いる場合、一般によく知られる整合条件
から、整合層はその固有音響インピーダンスを
znaとすると、
zna＝√1・2＝1.1×105N・Ｓ／m3 …(1)
なる値を有し、厚さが1/4波長であることが望ま
しい。 That is, the sound velocity v 1 of the piezoelectric ceramic vibrator 2 is approximately
3500m/s, the density ρ 1 is about 8000Kg/m 3 , and therefore the specific acoustic impedance z 1 expressed as the product of these values is approximately 3×10 7 N・S/m 3 . , On the other hand, the characteristic acoustic impedance z 2 of air at room temperature is approximately 400N・S/m 3 , so when using a single matching layer, from the generally well-known matching conditions, the matching layer has a characteristic acoustic impedance of
Assuming z na , it is desirable that the value is z na =√ 1 · 2 = 1.1×10 5 N·S/m 3 (1), and the thickness is 1/4 wavelength.
しかるに上記マイクロスフエアをシリコーン系
あるいはエポキシ系接着剤などに充てんした複合
材料あるいはシリコーン系ゴム単体の固有音響イ
ンピーダンスの値は９〜13×105N・Ｓ／m3程度
の値であり、圧電セラミツク振動子２と空気との
整合層に要求される固有音響インピーダンスの値
1.1×105N・Ｓ／m3に対して約１桁大きく、整合
層材料として最適ではなかつた。 However, the specific acoustic impedance of a composite material made of the microspheres filled with a silicone or epoxy adhesive or a single silicone rubber is approximately 9 to 13×10 5 N・S/m 3 , and piezoelectric Specific acoustic impedance value required for the matching layer between ceramic vibrator 2 and air
It was about one order of magnitude larger than 1.1×10 5 N·S/m 3 and was not optimal as a matching layer material.
また本出願人は、上記従来例における複合材料
より小さい固有音響インピーダンスの値を実現す
るため、エポキシ系接着剤あるいはシリコーン系
接着剤等の母材に低沸点炭化水素等の熱膨張性気
体を内包したプラスチツクなどから成る熱膨張性
微小中空球（以下熱膨張性バルーンと呼ぶ）を混
合した複合材料（以下熱膨張性複合材と呼ぶ）
を、100℃前後に加熱する事により、上記熱膨張
性複合材に混合された熱膨張性バルーンを膨張さ
せた薄層を、圧電セラミツク振動子と空気との整
合層材料として用いることを提案している。 In addition, the applicant has incorporated a thermally expandable gas such as a low-boiling hydrocarbon into a base material such as an epoxy adhesive or a silicone adhesive in order to achieve a value of specific acoustic impedance smaller than that of the composite material in the conventional example. A composite material (hereinafter referred to as a thermally expandable composite material) that is a mixture of thermally expandable micro hollow spheres (hereinafter referred to as a thermally expandable balloon) made of plastic, etc.
We propose to use a thin layer of a thermally expandable balloon mixed with the above thermally expandable composite material as a matching layer material between the piezoelectric ceramic vibrator and air by heating it to around 100℃. ing.
かかる提案について種々検討した結果以下の事
が判つた。熱膨張性複合材を100℃前後に加熱後、
常温に復帰させたのちの熱膨張性複合材の密度お
よび音速は、例えば母材に対する熱膨張性バルー
ンの混合重量比率を30％としたとき、加熱温度に
対して第２図に示すような傾向を有し、従つて密
度と音速の積で表わされる固有音響インピーダン
スの値は第３図に示すように変化する。従つて第
３図より加熱温度が約94℃のとき、熱膨張性複合
材の固有音響インピーダンスの値は1.1×105N・
Ｓ／m3となり圧電セラミツク振動子と空気との整
合層材料として最も適していることが分る。 As a result of various studies regarding this proposal, we found the following. After heating the thermally expandable composite material to around 100℃,
The density and sound velocity of the thermally expandable composite material after being returned to room temperature tend to change as shown in Figure 2 with respect to the heating temperature, for example, when the mixing weight ratio of the thermally expandable balloon to the base material is 30%. Therefore, the value of the characteristic acoustic impedance, which is expressed as the product of density and sound speed, changes as shown in FIG. Therefore, from Figure 3, when the heating temperature is approximately 94°C, the value of the specific acoustic impedance of the thermally expandable composite material is 1.1×10 5 N・
S/m 3 and is found to be the most suitable material for the matching layer between the piezoelectric ceramic vibrator and air.
しかし熱膨張性複合材の音速は加熱温度に対
し、第２図に示すごとく変化するので、ある一定
温度における熱膨張性複合材の音速の値に基いて
使用周波数における1/4波長として整合層の厚さ
を設定した場合、加熱温度が一定の設定値から変
動したとき音速が変化するため、これに伴つて整
合層厚さは1/4波長から誤差を生じ、整合条件が
満足されないことになる。また同様に第３図に示
すごとく、加熱温度の変動によつて熱膨張性複合
材料の固有音響インピーダンスの値も変化するた
め固有音響インピーダンスの大きさに関する第(1)
式の整合条件を満足しないという欠点を有してい
た。 However, the sound velocity of the thermally expandable composite changes with the heating temperature as shown in Figure 2, so based on the value of the sound speed of the thermally expandable composite at a certain temperature, the matching layer is set as 1/4 wavelength at the operating frequency. When setting the thickness of Become. Similarly, as shown in Fig. 3, the value of the characteristic acoustic impedance of the thermally expandable composite material also changes with fluctuations in the heating temperature.
This method has the disadvantage that it does not satisfy the matching condition of Eq.
また仮に加熱温度の変動が極めて小さく熱膨張
性複合材の音速あるいは固有音響インピーダンス
が設定値通りの値を得られた場合においても、整
合層の厚みは単一の使用周波数に対してのみ1/4
波長の条件を満たすものであるから、十分に広帯
域の整合層付き超音波トランスジユーサを実現す
ることは困難である。 Furthermore, even if the variation in heating temperature is extremely small and the sound velocity or specific acoustic impedance of the thermally expandable composite can be obtained as per the set value, the thickness of the matching layer should be reduced to 1/2 for only a single frequency of use. Four
Since the wavelength conditions are satisfied, it is difficult to realize an ultrasonic transducer with a matching layer having a sufficiently wide band.
さらに熱膨張性複合材を加熱することによつ
て、その中に混合された熱膨張性バルーンが膨張
するため、複合材を整合層として形成した薄層の
表面に小さな凹凸を生じて粗い面となるので、圧
電セラミツク等の振動子の音響放射面への整合層
の接着が不完全になるという欠点を有していた。 Furthermore, by heating the thermally expandable composite material, the thermally expandable balloon mixed therein expands, creating small irregularities on the surface of the thin layer formed of the composite material as a matching layer, resulting in a rough surface. Therefore, there is a drawback that the adhesion of the matching layer to the acoustic radiation surface of the vibrator, such as piezoelectric ceramic, is incomplete.
発明の目的
本発明は以上のような従来の欠点を改良するも
のであつて、圧電セラミツク振動子又は磁歪振動
子と、超音波伝搬媒体としての空気との音響的整
合が十分にとれ、広帯域化が可能で、振動子との
接合面が平滑である音響整合層を有した超音波ト
ランスジユーサを提供することを目的とする。Purpose of the Invention The present invention aims to improve the above-mentioned conventional drawbacks, and provides a piezoelectric ceramic vibrator or a magnetostrictive vibrator with sufficient acoustic matching with air as an ultrasonic propagation medium, and a wide band. An object of the present invention is to provide an ultrasonic transducer that has an acoustic matching layer that can be bonded to a vibrator and has a smooth surface.
発明の構成
本発明は上記目的を達成するため、合成樹脂中
に混合する微小中空球の粒径分布を音波放射方向
に対して連続的に変化させることによつて、整合
層の固有音響インピーダンスあるいは音速を音波
伝播方向に対して連続的に変化させ、整合層とし
て用いる熱膨張性複合材の加熱温度の変動によつ
て生ずる固有音響インピーダンスあるいは音速の
変動に基づく整合条件からのズレを吸収し、広帯
域化を実現するものであり、さらに整合層として
用いる複合材の薄層表面の振動子との接着面を平
滑にして接着をより完全に行なうものである。Structure of the Invention In order to achieve the above object, the present invention continuously changes the particle size distribution of micro hollow spheres mixed in a synthetic resin with respect to the sound wave radiation direction. Continuously changing the sound speed in the sound wave propagation direction to absorb deviations from matching conditions due to changes in the specific acoustic impedance or sound speed caused by changes in the heating temperature of the thermally expandable composite material used as the matching layer, It is intended to realize a wide band, and furthermore, the adhesion surface of the thin layer of the composite material used as the matching layer to the vibrator is smoothed to achieve more complete adhesion.
実施例の説明
以下に本発明の実施例を図面を用いて説明す
る。DESCRIPTION OF EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.
第４図は本発明の一実施例を示す断面構造図で
あつて、エポキシ系接着剤あるいはシリコーン系
接着剤等の母材４に微小中空球５を混合した複合
材料において、微小中空球５の粒径を複合材料の
厚さ方向に連続的に変化させた薄層６を圧電セラ
ミツク振動子又は磁歪振動子２の音波放射面３に
接着し整合層とするもので、音波放射方向に沿つ
て微小中空球５の粒径が大きくなるような粒径分
布を持たせてある。したがつて、第２、第３図か
ら分る通り、音速および音響インピーダンスも音
波放射方向に沿つて連続的に小さくなるため、
（加熱温度が高ければ粒径は大きくなる）広い周
波数範囲にわたつて振動子２と音波伝搬媒体であ
る空気との整合をとることが可能になる。 FIG. 4 is a cross-sectional structural diagram showing one embodiment of the present invention, in which hollow micro spheres 5 are mixed in a base material 4 such as epoxy adhesive or silicone adhesive in a composite material. A thin layer 6 whose grain size is continuously changed in the thickness direction of the composite material is bonded to the sound wave emitting surface 3 of the piezoelectric ceramic vibrator or magnetostrictive vibrator 2 to form a matching layer. The particle size distribution is such that the particle size of the micro hollow spheres 5 becomes large. Therefore, as can be seen from Figures 2 and 3, the sound velocity and acoustic impedance also decrease continuously along the sound wave radiation direction.
(The higher the heating temperature, the larger the particle size.) It becomes possible to match the vibrator 2 with air, which is a sound wave propagation medium, over a wide frequency range.
上記のような整合層の製造方法を第５図を用い
て説明する。 A method of manufacturing the matching layer as described above will be explained with reference to FIG.
第５図において６は熱膨張性バルーン５をエポ
キシ系接着剤又はシリコーン系接着剤等の母材４
に混合した熱膨張性複合材から成る薄層であり、
この薄層６の一方の面７に温度T1なる熱源９を
接し、他方の面８に温度T2なる熱源１０（T1＜
T2とする）を接して薄層６に温度勾配を持たせ
ることにより、熱膨張性バルーン５は熱源１０に
近い側ほど膨張率が大きくなり、従つて音速およ
び音響インピーダンスは小さくなる。このように
して得た薄層６を第４図に示すごとく、面７を圧
電セラミツク振動子又は磁歪振動子２の音波放射
面３に接着する。薄層６の厚さは薄層６を伝搬す
る音波の平均的な波長の1/4又はその近傍に選ぶ。 In FIG. 5, reference numeral 6 indicates that the thermally expandable balloon 5 is attached to a base material 4 such as epoxy adhesive or silicone adhesive.
A thin layer of thermally expandable composite mixed with
One surface 7 of this thin layer 6 is connected to a heat source 9 having a temperature of T 1 , and the other surface 8 is connected to a heat source 10 having a temperature of T 2 (T 1 <
By creating a temperature gradient in the thin layer 6 in contact with T 2 ), the coefficient of expansion of the thermally expandable balloon 5 becomes larger on the side closer to the heat source 10 , and the speed of sound and acoustic impedance become smaller. The surface 7 of the thus obtained thin layer 6 is adhered to the sound emitting surface 3 of the piezoelectric ceramic vibrator or magnetostrictive vibrator 2, as shown in FIG. The thickness of the thin layer 6 is selected to be 1/4 of the average wavelength of the sound waves propagating through the thin layer 6 or close thereto.
発明の効果
以上のように本発明は、整合層の微小中空球の
粒径が音波放射方向に向つて大きくなるため、整
合層の音速又は音響インピーダンスが超音波振動
子に近い側から音波放射方向に沿つて連続的に小
さくなり、広い周波数範囲にわたつて平坦な特性
を有する超音波トランスジユーサを実現すること
ができる。また、整合層の、超音波振動子の音波
放射面に近い側の表面近傍は粒径の細かい粒子が
分布しているので、この表面は平滑となり、超音
波振動子との接着が容易である。Effects of the Invention As described above, in the present invention, since the particle size of the micro hollow spheres in the matching layer increases in the direction of sound wave radiation, the sound velocity or acoustic impedance of the matching layer increases from the side closer to the ultrasonic transducer in the sound wave radiation direction. It is possible to realize an ultrasonic transducer that becomes smaller continuously along the curve and has flat characteristics over a wide frequency range. In addition, since fine particles are distributed near the surface of the matching layer on the side closer to the sound wave emission surface of the ultrasonic vibrator, this surface becomes smooth and can be easily bonded to the ultrasonic vibrator. .
第１図は従来の超音波トランスジユーサを示す
断面図、第２図は熱膨張性複合材における密度及
び音速の温度変化を示す図、第３図は熱膨張性複
合材における固有音響インピーダンスの温度変化
を示す図、第４図は本発明の一実施例を示す断面
図、第５図は同実施例の製造方法を説明するため
の断面図である。
４……母材、５……熱膨張性バルーン、６……
熱膨張性複合材、９，１０……熱源。
Figure 1 is a cross-sectional view of a conventional ultrasonic transducer, Figure 2 is a diagram showing changes in density and sound velocity with temperature in a thermally expandable composite, and Figure 3 is a graph of the characteristic acoustic impedance of a thermally expandable composite. FIG. 4 is a cross-sectional view showing an embodiment of the present invention, and FIG. 5 is a cross-sectional view showing a manufacturing method of the same embodiment. 4... Base material, 5... Thermally expandable balloon, 6...
Thermal expandable composite material, 9, 10... heat source.
Claims (1)
を、音響整合層として超音波振動子に接合し、前
記微小中空球の粒径分布を音波の放射方向に向か
つて大きくなるように連続的に変化させたことを
特徴とする超音波トランスジユーサ。 ２ 超音波振動子が、圧電セラミツク振動子また
は磁歪振動子からなることを特徴とする特許請求
の範囲第１項記載の超音波トランスジユーサ。[Claims] 1. A thin film made of a mixture of hollow microspheres in a synthetic resin is bonded to an ultrasonic vibrator as an acoustic matching layer, and the particle size distribution of the hollow microspheres is directed in the radiation direction of sound waves. An ultrasonic transducer characterized by a continuous change in size. 2. The ultrasonic transducer according to claim 1, wherein the ultrasonic vibrator is a piezoelectric ceramic vibrator or a magnetostrictive vibrator.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58044946A JPS59171295A (en) | 1983-03-17 | 1983-03-17 | Ultrasonic wave transducer |
| DE8484301823T DE3478357D1 (en) | 1983-03-17 | 1984-03-16 | Ultrasonic transducers having improved acoustic impedance matching layers |
| US06/590,465 US4523122A (en) | 1983-03-17 | 1984-03-16 | Piezoelectric ultrasonic transducers having acoustic impedance-matching layers |
| EP84301823A EP0119855B2 (en) | 1983-03-17 | 1984-03-16 | Ultrasonic transducers having improved acoustic impedance matching layers |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58044946A JPS59171295A (en) | 1983-03-17 | 1983-03-17 | Ultrasonic wave transducer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59171295A JPS59171295A (en) | 1984-09-27 |
| JPS643119B2 true JPS643119B2 (en) | 1989-01-19 |
Family
ID=12705646
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58044946A Granted JPS59171295A (en) | 1983-03-17 | 1983-03-17 | Ultrasonic wave transducer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59171295A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62120799A (en) * | 1985-11-21 | 1987-06-02 | Tokyo Keiki Co Ltd | Ultrasonic transducer |
| JP2651140B2 (en) * | 1986-07-16 | 1997-09-10 | 株式会社 村田製作所 | Aerial ultrasonic transducer |
| JP3655860B2 (en) * | 2001-09-27 | 2005-06-02 | アロカ株式会社 | Ultrasonic probe |
| US7808156B2 (en) * | 2006-03-02 | 2010-10-05 | Visualsonics Inc. | Ultrasonic matching layer and transducer |
| JP6295370B2 (en) * | 2015-02-27 | 2018-03-14 | 株式会社日立製作所 | Ultrasonic probe and ultrasonic diagnostic apparatus using the same |
-
1983
- 1983-03-17 JP JP58044946A patent/JPS59171295A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59171295A (en) | 1984-09-27 |
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