JPS6139715A - Ultrasonic wave delay line - Google Patents

Abstract

PURPOSE:To reduce the impedance of a piezoelectric converter with simple structure and excellent workability by separating electrically only an upper electrode of an input/output piezoelectric converter into two and leading out a lead from the two separated upper electrodes. CONSTITUTION:The upper electrode is separated electrically into two parts by using a mask. Leads 6, 7 are bonded respectively to the upper electrodes 4, 5 by using a conductive adhesives such as Silvest. Although the ultrasonic wave irradiated into an ultrasonic wave delay medium from beneath the upper electrode 4 and the ultrasonic wave irradiated into the ultrasonic wave delay medium from beneath the upper electrode 5 are shifted in phase by 180 deg., since the output piezoelectric converter is constituted similarly as the input piezoelectric converter, an output voltage is generated between the leads. Although the ultrasonic waves whose phases are inverted mutually reach one of the split electrodes of the output converter because of the spread of the ultrasonic wave beam and an output voltage is lowered equivalently, the spread in the beam is neglected substantially at high frequencies being several tens of MHz or over.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明はビデオカメラ、テレビ等に用いる超音波遅延線
に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ultrasonic delay line used in video cameras, televisions, and the like.

（従来例の構成とその問題点） 超音波遅延線はガラス等の固体超音波遅延媒体の超音波
伝搬主面に垂直な１つまたは２つの平面上に入出力圧電
変換子を設け、入力圧電変換子に印加した高周波−気信
号を超音波信号に変換し、一定の遅延時間後、出力圧電
変換子で再び電気信号に変換するもの庫あ２る。このよ
うな超音波遅延線において、遅延６い電気信号の周波数
が数十メガヘルツと高くなると入出力圧電変換子の共振
周波数もこれに応じそ高くせねばならないた込、圧電変
換子の厚さが薄くなり、電気的インピーダンスが小さく
な）遅延線を駆動しに・くくなる。インピーダンスを高
くするため圧電変換子の電極面積を小さくすると超音波
の広がりによる損失のため挿入損失が犬きくなってしま
う。そのため従来用いられているのは入出力圧電変換子
を直列２分割して電極面積を小さ゛くすることなくイン
ピーダンスを高める手法である。第２図に従来用いられ
ている超音波遅延線の直列２分割した圧電変換子を示す
。１は超音波遅延線体、２，９は下地電極、３は圧電変
換、子Ｊ４”、５は圧電変換子の上部電極、６．７．８
はリード線である。との圧電変換子は下地電極２，９と
上部電極４，５を電気的に分離し、一方の上部電極４と
一方の下地電極９をＩＪ−ド線８で接続し、下地電極２
と上部電極５からリード線６，７を外部に引き出したも
のである。このよう々構成で圧電変換子を直列２分割す
ることによシミ極面積を小さくすることなくインピーダ
ンスを高くするとともに分割した２つの圧電変換子を同
相で駆動している。しかし、このよう々従来の構成では
リード線８で上部電極４と下地電極９を橋渡しせねばな
らな己ため作業性が悪くまたリード線７，８間の接触の
危険性もあった。(Configuration of conventional example and its problems) An ultrasonic delay line has an input/output piezoelectric transducer installed on one or two planes perpendicular to the main plane of ultrasonic propagation of a solid ultrasonic delay medium such as glass. There is also a device that converts the high frequency air signal applied to the transducer into an ultrasonic signal, and after a certain delay time, converts it back into an electrical signal with an output piezoelectric transducer. In such an ultrasonic delay line, as the frequency of the delayed electrical signal increases to several tens of megahertz, the resonant frequency of the input and output piezoelectric transducers must also increase accordingly. This makes it difficult to drive delay lines (thinner and with lower electrical impedance). If the electrode area of the piezoelectric transducer is made smaller in order to increase the impedance, the insertion loss will increase due to loss due to the spread of ultrasonic waves. Therefore, a method conventionally used is to divide the input/output piezoelectric transducer into two parts in series to increase the impedance without reducing the electrode area. FIG. 2 shows a conventionally used piezoelectric transducer in which an ultrasonic delay line is divided into two parts in series. 1 is an ultrasonic delay line body, 2 and 9 are base electrodes, 3 is a piezoelectric transducer, J4", 5 is an upper electrode of the piezoelectric transducer, 6.7.8
is the lead wire. The piezoelectric transducer electrically separates the base electrodes 2, 9 and the upper electrodes 4, 5, connects one upper electrode 4 and one base electrode 9 with an IJ wire 8, and connects the base electrode 2
Lead wires 6 and 7 are drawn out from the upper electrode 5. With this configuration, by dividing the piezoelectric transducer into two in series, the impedance is increased without reducing the stain pole area, and the two divided piezoelectric transducers are driven in the same phase. However, in such a conventional structure, the lead wire 8 must bridge the upper electrode 4 and the base electrode 9, resulting in poor workability and the risk of contact between the lead wires 7 and 8.

（発明の目的） 本発明はこのよう々欠点を除去するもので、従来のよう
な配線を用いることなく簡単な構造で作業性よく圧電変
換子のインピーダンスを小さくすることを目的とする。(Objective of the Invention) The present invention eliminates these drawbacks and aims to reduce the impedance of a piezoelectric transducer with a simple structure and good workability without using conventional wiring.

（発明の構成） この目的を達成するため本発明は入出力圧電変換子の上
部電極のみを電気的に２つに分離し、この分離した２つ
の上部電極からリード線を引き出したものである。(Structure of the Invention) In order to achieve this object, the present invention electrically separates only the upper electrode of the input/output piezoelectric transducer into two parts, and leads out the lead wires from the two separated upper electrodes.

（実施例の説明） 以下、本発明の実施例を第１図を用いて説明する。■は
ガラス等の超音波遅延媒体である。２け下地電極であり
、Ｎｉ−Ｃｒを下地に金、銀を蒸着しである。３はセラ
ミック、圧電単結晶等の圧電変換子であり下地電極と電
気的、機械的に接触している。４，５は圧電変換子の上
部電極であわ下地電極と同様にＮｉ−Ｃｒ　、金、銀を
蒸着しである。(Description of Examples) Examples of the present invention will be described below with reference to FIG. (2) is an ultrasonic delay medium such as glass. It has two base electrodes, and gold and silver are deposited on a Ni-Cr base. 3 is a piezoelectric transducer made of ceramic, piezoelectric single crystal, etc., which is in electrical and mechanical contact with the base electrode. 4 and 5 are the upper electrodes of the piezoelectric transducer, and Ni--Cr, gold, and silver are deposited thereon in the same way as the base electrode.

そしてこの上部電極はマスクを用い２つの部分に電気的
に分離している。リード線６，７は上部電極４，５の各
々にシルベスト等の導電性接着剤で接着する。This upper electrode is electrically separated into two parts using a mask. The lead wires 6 and 7 are bonded to each of the upper electrodes 4 and 5 using a conductive adhesive such as Silvest.

第１図には入力圧電変換子のみしか示していないが超音
波が遅延媒体中を伝搬し反射をくりかえして到達する、
遅延媒体の超音波伝搬主面に垂直々他の一平面に設けた
出力圧電変換子も、この入力圧電変換子と同様の構成と
なっている。第１図のよう々構成をとると上部電極４の
直下から超音波遅延媒体中に放射される超音波と上部電
極５の直下から超音波遅延媒体中に放射される超音波の
位相は１８００反転しているが、出力圧電変換子の構成
が前述のように入力圧電変換子と同様であるためリード
線間には出力電圧が発生する。また超音波ビームの広が
シのため出力圧電変換子の分割電極の一方に互いに位相
の反転した超音波が到達し等何点に出力電圧が低下する
が、数十メガヘルツ以上の高い周波数になるとビームの
広がりは実質的に無視できるように々る。Although only the input piezoelectric transducer is shown in Figure 1, the ultrasonic wave propagates through the delay medium and reaches it after repeated reflections.
The output piezoelectric transducer provided on another plane perpendicular to the main plane of ultrasonic propagation of the delay medium has the same configuration as the input piezoelectric transducer. When the configuration shown in Fig. 1 is adopted, the phase of the ultrasonic wave radiated into the ultrasonic delay medium from directly below the upper electrode 4 and the phase of the ultrasonic wave radiated into the ultrasonic delay medium from directly below the upper electrode 5 is reversed by 1800 degrees. However, since the configuration of the output piezoelectric transducer is similar to that of the input piezoelectric transducer as described above, an output voltage is generated between the lead wires. Also, due to the spread of the ultrasound beam, ultrasound waves with opposite phases reach one of the divided electrodes of the output piezoelectric transducer, causing the output voltage to drop at some point, but when the frequency reaches a high frequency of several tens of megahertz or more, The beam spread is virtually negligible.

（発明の効果） 本発明は簡単々構成で作業性がよく入出力変換子のイン
ピーダンスが高いため駆動源とのマツチングがよい遅延
線を提供しうるものである。(Effects of the Invention) The present invention can provide a delay line that has a simple configuration, is easy to work with, and has a high impedance of the input/output converter, so that it matches well with the drive source.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の超音波遅延線の圧電変換子、第２図は
従来の超音波遅延線の圧電変換子である。 ２．９・・・下地電極、３・・・圧電変換子、４，５・
・・上部電極、６，７．８・・・リード線。 第１図 第２図 ゛　７FIG. 1 shows a piezoelectric transducer for an ultrasonic delay line according to the present invention, and FIG. 2 shows a piezoelectric transducer for a conventional ultrasonic delay line. 2.9... Base electrode, 3... Piezoelectric transducer, 4,5...
...Top electrode, 6,7.8...Lead wire. Figure 1 Figure 2 7

Claims (1)

【特許請求の範囲】[Claims] ガラス等の固体超音波遅延媒体の超音波伝搬主面に垂直
な１つまたは２つの平面に下地電極を設け、該下地電極
上に、上部電極を電気的に二つの部分に分割した入力圧
電変換子と出力圧電変換子を各々接着し、入力圧電変換
子の分割した二つの上部電極上からリード線を引き出し
入力端子とし、出力圧電変換子の分割した二つの上部電
極上からリード線を引き出し出力端子としたことを特徴
とする超音波遅延線。An input piezoelectric transducer in which a base electrode is provided on one or two planes perpendicular to the main plane of ultrasound propagation of a solid ultrasonic delay medium such as glass, and an upper electrode is electrically divided into two parts on the base electrode. Glue the output piezoelectric transducer and the output piezoelectric transducer, pull out the lead wires from above the two divided upper electrodes of the input piezoelectric transducer to serve as input terminals, and pull out the lead wires from the two divided upper electrodes of the output piezoelectric transducer for output. An ultrasonic delay line characterized by having a terminal.