JP2007115866A - Ultrasonic wave vibrator - Google Patents

Ultrasonic wave vibrator Download PDF

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JP2007115866A
JP2007115866A JP2005305203A JP2005305203A JP2007115866A JP 2007115866 A JP2007115866 A JP 2007115866A JP 2005305203 A JP2005305203 A JP 2005305203A JP 2005305203 A JP2005305203 A JP 2005305203A JP 2007115866 A JP2007115866 A JP 2007115866A
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piezoelectric body
electrode
ultrasonic wave
opening
vibration
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Yasuhide Matsuo
泰秀 松尾
Tomohiko Kaneko
智彦 金子
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Tamura Corp
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Tamura Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic wave vibrator which assures stable vibration in the ultrasonic wave oscillation and can prevent sudden reduction in efficiency even if frequency of drive voltage changes. <P>SOLUTION: The ultrasonic wave vibrator comprises a plate-type piezoelectric material 1 for generating ultrasonic wave through vibration and electrodes 2, 3 provided respectively at the upper and lower surfaces of the same piezoelectric material 1 permitting application of a voltage for driving this piezoelectric material 1. In this ultrasonic wave vibrator, at least one aperture 2A is provided on at least one electrode 2A. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

この発明は、高周波電圧により駆動される超音波振動子に関する。   The present invention relates to an ultrasonic transducer driven by a high frequency voltage.

超音波振動子には、圧電体として圧電セラミックスを用いた圧電セラミックス振動子がある。このような圧電セラミックス振動子を図４に示す。図４の圧電セラミックス振動子は圧電体１０１と電極１０２、１０３とで構成されている。圧電体１０１は板状であり、圧電体１０１の上下の面の全面には電極１０２、１０３がそれぞれ設けられている。こうした圧電セラミックス振動子では、周波数が超音波振動子の共振周波数である高周波電圧が、駆動電圧として電極１０２、１０３に加えられると、圧電体１０１が振動して超音波を発生する。このとき、圧電体１０１は主に厚み方向に振動して超音波を発生する。   As the ultrasonic vibrator, there is a piezoelectric ceramic vibrator using a piezoelectric ceramic as a piezoelectric body. Such a piezoelectric ceramic vibrator is shown in FIG. The piezoelectric ceramic vibrator shown in FIG. 4 includes a piezoelectric body 101 and electrodes 102 and 103. The piezoelectric body 101 is plate-shaped, and electrodes 102 and 103 are provided on the entire upper and lower surfaces of the piezoelectric body 101, respectively. In such a piezoelectric ceramic vibrator, when a high frequency voltage whose frequency is the resonance frequency of the ultrasonic vibrator is applied to the electrodes 102 and 103 as a drive voltage, the piezoelectric body 101 vibrates and generates an ultrasonic wave. At this time, the piezoelectric body 101 mainly generates vibrations in the thickness direction.

従来の圧電セラミックス振動子には、次の問題点がある。従来の圧電セラミックス振動子に駆動電圧を加えて超音波を発生するとき、圧電体１０１の厚み方向の振動と共に、圧電体１０１の長さ方向の振動も発生する。つまり、図５の特性ｍに示すように、厚さ方向の振動によるインピーダンス変化と共に、特性ｎに示すように、長さ方向の振動によるインピーダンス変化も発生する。このために、共振周波数ｆ１０１の駆動電圧を電極１０２、１０３に加えても、特性ｎにより圧電体１０１の駆動が不安定になる。   The conventional piezoelectric ceramic vibrator has the following problems. When an ultrasonic wave is generated by applying a driving voltage to a conventional piezoelectric ceramic vibrator, vibration in the length direction of the piezoelectric body 101 is generated along with vibration in the thickness direction of the piezoelectric body 101. That is, as indicated by the characteristic m in FIG. 5, an impedance change due to vibration in the length direction also occurs as indicated by the characteristic n, along with the impedance change due to vibration in the thickness direction. For this reason, even if a drive voltage having the resonance frequency f101 is applied to the electrodes 102 and 103, the drive of the piezoelectric body 101 becomes unstable due to the characteristic n.

また、従来の圧電セラミックス振動子は振動の鋭さを示す値Ｑが高い。つまり、共振周波数ｆ１０１におけるインピーダンスが鋭く低下する。このために、駆動電圧の周波数が共振周波数ｆ１０１から少しでも外れると、インピーダンスが急激に高くなり、効率が大幅に低下してしまう。   Further, the conventional piezoelectric ceramic vibrator has a high value Q indicating the sharpness of vibration. That is, the impedance at the resonance frequency f101 decreases sharply. For this reason, when the frequency of the drive voltage deviates even slightly from the resonance frequency f101, the impedance rapidly increases and the efficiency is significantly reduced.

この発明は、前記の課題を解決し、超音波発振の際の駆動を安定し、しかも、駆動電圧の周波数が変化しても、効率の急激な低下を防ぐことができる超音波振動子を提供することにある。   The present invention provides an ultrasonic transducer that solves the above-mentioned problems, stabilizes driving during ultrasonic oscillation, and can prevent a sudden drop in efficiency even when the frequency of the driving voltage changes. There is to do.

前記課題を解決するために、請求項１の発明は、振動により超音波を発生する板状の圧電体と、この圧電体の上面および下面にそれぞれ設けられ、この圧電体を駆動するための電圧が加えられる電極とを具備する超音波振動子において、前記少なくとも一方の電極に、少なくとも１以上の開口部を設けたことを特徴とする超音波振動子である。
請求項２の発明は、請求項１に記載の超音波振動子において、前記上下面の電極は印刷によって設けられ、前記開口部は印刷の際に設けられ、電極が印刷されない領域であることを特徴とする。
請求項３の発明は、請求項１または２に記載の超音波振動子において、前記開口部の形状は円形、楕円、長円、多角形、または線状であることを特徴とする。 In order to solve the above-mentioned problems, the invention of claim 1 includes a plate-like piezoelectric body that generates ultrasonic waves by vibration, and a voltage for driving the piezoelectric body provided on the upper and lower surfaces of the piezoelectric body. An ultrasonic transducer comprising an electrode to which at least one electrode is applied, wherein at least one or more openings are provided in the at least one electrode.
According to a second aspect of the present invention, in the ultrasonic transducer according to the first aspect, the upper and lower surface electrodes are provided by printing, the opening is provided at the time of printing, and the electrode is not printed. Features.
According to a third aspect of the present invention, in the ultrasonic transducer according to the first or second aspect, the shape of the opening is a circle, an ellipse, an ellipse, a polygon, or a line.

請求項１の発明によれば、少なくとも一方の電極に、少なくとも１以上の開口部を設けたので、電極に電圧を加えても、開口部には電界が加わらない。これにより、電極の開口部に位置する圧電体の振動を抑えて、圧電体の長さ方向の振動を抑制することができる。また、電極の開口部に位置する圧電体の振動を抑制するので、超音波振動子のＱが低下し、駆動電圧の周波数が変化しても、効率の急激な低下を防ぐことができる。
請求項２の発明によれば、印刷で電極を設ける際に、電極を印刷しない領域を開口部としたので、簡単に開口部を形成でき、また、コストを抑えて、超音波発振の際の駆動を安定し、効率の急激な低下を防ぐことができる。
請求項３の発明によれば、開口部を単純な矩形とした場合、角部にひびが生じ易いが、本発明では開口部の形状を円形、楕円、長円、多角形、および線状の中の１つとしたので、圧電体の振動の際に開口部の割れ等の発生を防ぐか低減することができる。 According to the invention of claim 1, since at least one or more openings are provided in at least one of the electrodes, an electric field is not applied to the openings even when a voltage is applied to the electrodes. Thereby, the vibration of the piezoelectric body located in the opening part of an electrode can be suppressed, and the vibration of the length direction of a piezoelectric body can be suppressed. Further, since the vibration of the piezoelectric body located at the opening of the electrode is suppressed, even if the Q of the ultrasonic transducer is lowered and the frequency of the drive voltage is changed, it is possible to prevent a rapid drop in efficiency.
According to the second aspect of the present invention, when the electrode is provided by printing, the region where the electrode is not printed is used as the opening. Therefore, the opening can be easily formed, and the cost can be reduced. The drive can be stabilized and a sudden drop in efficiency can be prevented.
According to the invention of claim 3, when the opening is a simple rectangle, the corner is likely to crack, but in the present invention, the shape of the opening is circular, oval, oval, polygonal, and linear. Since it is one of them, it is possible to prevent or reduce the occurrence of cracks and the like of the opening when the piezoelectric body vibrates.

つぎに、この発明の実施の形態について説明する。図１は、この発明の実施形態を示す圧電セラミックス振動子の斜視図である。この圧電セラミックス振動子の用途としては、例えばメガネの洗浄用の超音波洗浄機に用いられる。図１の圧電セラミックス振動子は、圧電体１とその上下面にそれぞれ設けられた電極２、３とを備えて構成されている。圧電体１は、板状であり、電極２、３を介して、周波数が共振周波数である駆動電圧が加えられると、主に厚み方向（矢印Ａまたはその逆方向）に振動して、超音波を発生する。   Next, an embodiment of the present invention will be described. FIG. 1 is a perspective view of a piezoelectric ceramic vibrator showing an embodiment of the present invention. As an application of this piezoelectric ceramic vibrator, for example, it is used in an ultrasonic cleaning machine for cleaning glasses. The piezoelectric ceramic vibrator of FIG. 1 includes a piezoelectric body 1 and electrodes 2 and 3 provided on the upper and lower surfaces thereof. The piezoelectric body 1 has a plate shape, and when a drive voltage having a resonance frequency is applied via the electrodes 2 and 3, the piezoelectric body 1 mainly vibrates in the thickness direction (arrow A or the opposite direction), and ultrasonic waves Is generated.

電極２は、印刷により圧電体１の一方の板面に設けられた金属膜である。この実施の形態では、円形の開口部２Ａが電極２に設けられている。なお、図１では、図面の複雑化を避けるために、代表的な開口部に符号を付けている。こうした開口部２Ａの面積は、圧電体１の板面の３［％］以上であり６０［％］以下であることが適切である。３［％］以下だと所望の効果が期待できないためである。また、６０［％］以上であると、圧電体１に所定の電圧を印加できず動作不良を起こすおそれがあるためである。開口部２Ａは、図２に示すように、電極が印刷されない領域、つまり、圧電体１に対する未印刷領域であり、この実施の形態では、開口部２Ａは、圧電体１の長手方向に対して規則的に並んで配置され、また、圧電体１の両端部には設けられていない。さらに、開口部２Ａの形状が円形のような弧状にしてあるので、超音波を出力するために圧電体１が振動しても、開口部２Ａのひび割れ等の発生を防ぐことができる。   The electrode 2 is a metal film provided on one plate surface of the piezoelectric body 1 by printing. In this embodiment, a circular opening 2 </ b> A is provided in the electrode 2. In FIG. 1, reference numerals are given to typical openings in order to avoid complication of the drawing. The area of the opening 2A is appropriately 3% or more and 60% or less of the plate surface of the piezoelectric body 1. This is because the desired effect cannot be expected when the ratio is 3% or less. Further, if it is 60 [%] or more, a predetermined voltage cannot be applied to the piezoelectric body 1 and a malfunction may occur. As shown in FIG. 2, the opening 2 </ b> A is a region where no electrode is printed, that is, an unprinted region with respect to the piezoelectric body 1. In this embodiment, the opening 2 </ b> A is in the longitudinal direction of the piezoelectric body 1. They are arranged regularly and are not provided at both ends of the piezoelectric body 1. Further, since the shape of the opening 2A is an arc shape such as a circle, even if the piezoelectric body 1 vibrates in order to output ultrasonic waves, it is possible to prevent the opening 2A from cracking.

電極３も、印刷により圧電体１の他方の板面に設けられた金属膜である。この電極３は圧電体１の他方の板面の全面に設けられている。   The electrode 3 is also a metal film provided on the other plate surface of the piezoelectric body 1 by printing. The electrode 3 is provided on the entire other plate surface of the piezoelectric body 1.

前記構成の圧電セラミックス振動子の電極２、３に周波数が共振周波数である、高周波の駆動電圧が加えられると、電極２の開口部２Ａに位置する圧電体１には、駆動電圧による電界が加えられない。したがって、開口部２Ａの下部では、圧電体１の振動が抑えられ、圧電体１の長さ方向の振動が抑制される。長さ方向の振動が抑制されると、図３に示すように、圧電体１の長さ方向の振動によるインピーダンス変化の発生を防ぐことができる。つまり、従来の超音波振動子の長さ方向の振動によるインピーダンス変化（図５に示す特性ｎ）の発生を防ぐことができる。この結果、共振周波数ｆ１の駆動電圧を、電極２と電極３との間に加えると、圧電体１の駆動を安定化することができる。   When a high-frequency driving voltage having a resonance frequency is applied to the electrodes 2 and 3 of the piezoelectric ceramic vibrator having the above-described configuration, an electric field due to the driving voltage is applied to the piezoelectric body 1 positioned in the opening 2A of the electrode 2 I can't. Accordingly, the vibration of the piezoelectric body 1 is suppressed below the opening 2A, and the vibration of the piezoelectric body 1 in the length direction is suppressed. When the vibration in the length direction is suppressed, as shown in FIG. 3, it is possible to prevent an impedance change due to the vibration in the length direction of the piezoelectric body 1. That is, the impedance change (characteristic n shown in FIG. 5) due to the vibration in the length direction of the conventional ultrasonic transducer can be prevented. As a result, when the driving voltage having the resonance frequency f1 is applied between the electrode 2 and the electrode 3, the driving of the piezoelectric body 1 can be stabilized.

また、従来の圧電セラミックス振動子は、振動子の振動の鋭さを示す値Ｑが高い。つまり、共振周波数ｆ１０１におけるインピーダンスが鋭く低下する。このために、駆動電圧の周波数が共振周波数ｆ１０１から少しでも外れると、インピーダンスが鋭く高くなり、効率が急激に低下してしまう。これに対して、この実施の形態による圧電セラミックス振動子では、駆動電圧が電極２と電極３との間に加えられると、電極２の開口部２Ａの下部では、圧電体１の振動が抑えられ、圧電体１の長さ方向の振動が抑制される。この結果、図３に示すようにＱを低くすることができ、駆動電圧の周波数が変化しても、効率の急激な低下を防ぐことができる。   Further, the conventional piezoelectric ceramic vibrator has a high value Q indicating the sharpness of vibration of the vibrator. That is, the impedance at the resonance frequency f101 decreases sharply. For this reason, when the frequency of the drive voltage deviates even slightly from the resonance frequency f101, the impedance becomes sharply high, and the efficiency drops sharply. On the other hand, in the piezoelectric ceramic vibrator according to this embodiment, when a driving voltage is applied between the electrode 2 and the electrode 3, the vibration of the piezoelectric body 1 is suppressed below the opening 2A of the electrode 2. The vibration in the length direction of the piezoelectric body 1 is suppressed. As a result, as shown in FIG. 3, Q can be lowered, and even if the frequency of the drive voltage changes, a rapid decrease in efficiency can be prevented.

この実施の形態による超音波振動子は、例えば、前述のように洗浄器に用いられる。洗浄器には、通常、複数の超音波振動子が用いられ、従来の超音波振動子ではＱが高いので、各振動子の特性が均一でない場合や駆動電圧の周波数が共振周波数から外れると、各振動子が出力する超音波に強弱が発生し、洗浄にむらが生じる。しかし、この実施の形態による超音波振動子を洗浄に用いると、Ｑが低いので、各振動子の特性が均一でない場合や駆動電圧の周波数が共振周波数から外れても、各振動子の効率に大幅な変動がなく、各振動子が出力する超音波のレベルが大体同じであり、洗浄にむらが生じることを防ぐことができる。   The ultrasonic transducer according to this embodiment is used in a cleaning device as described above, for example. In the cleaning device, a plurality of ultrasonic vibrators are usually used, and the conventional ultrasonic vibrator has a high Q. Therefore, when the characteristics of the vibrators are not uniform or the frequency of the drive voltage deviates from the resonance frequency, The ultrasonic wave output from each vibrator is strong and weak, resulting in uneven cleaning. However, when the ultrasonic transducer according to this embodiment is used for cleaning, since the Q is low, the efficiency of each transducer is improved even if the characteristics of each transducer are not uniform or the frequency of the drive voltage deviates from the resonance frequency. There is no significant fluctuation, the level of ultrasonic waves output from each transducer is approximately the same, and uneven cleaning can be prevented.

以上、この発明の実施の形態を詳述してきたが、具体的な構成はこの実施の形態に限られるものではなく、この発明の要旨を逸脱しない範囲の設計の変更等があっても、この発明に含まれる。たとえば、この実施の形態では、開口部２Ａが電極２に対して規則性をもって配列されているが、ランダムに配置されてもよい。また、開口部２Ａの形状は円形であったが、この他に楕円、長円、多角形、線状でもよい。これらの形状でも、圧電体の振動の際に、開口部の割れ等の発生を防ぐことができる。また、電極３には開口部を形成しなかったが、電極３に対して電極２と上下対称にまたは上下非対称に開口部を設けてもよい。また、下面側の電極３に開口部を形成し、上面側の電極２は開口部なしとしても良い。   The embodiment of the present invention has been described in detail above, but the specific configuration is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention, Included in the invention. For example, in this embodiment, the openings 2A are regularly arranged with respect to the electrode 2, but may be arranged at random. In addition, the shape of the opening 2A is circular, but may be an ellipse, an ellipse, a polygon, or a line. Even in these shapes, it is possible to prevent the opening portion from cracking when the piezoelectric body vibrates. In addition, although no opening is formed in the electrode 3, the opening may be provided vertically or asymmetrically with the electrode 2 with respect to the electrode 3. Further, an opening may be formed in the electrode 3 on the lower surface side, and the electrode 2 on the upper surface side may have no opening.

この発明の実施形態を示す圧電セラミックス振動子の斜視図である。1 is a perspective view of a piezoelectric ceramic vibrator showing an embodiment of the present invention. 図１のＩ-Ｉ断面を示す断面図である。It is sectional drawing which shows the II cross section of FIG. この実施形態による圧電セラミックス振動子の周波数―インピーダンス特性を示す図である。It is a figure which shows the frequency-impedance characteristic of the piezoelectric ceramic vibrator by this embodiment. 従来の圧電セラミックス振動子を示す斜視図である。It is a perspective view which shows the conventional piezoelectric ceramic vibrator. 従来の圧電セラミックス振動子の周波数―インピーダンス特性を示す図である。It is a figure which shows the frequency-impedance characteristic of the conventional piezoelectric ceramic vibrator.

符号の説明Explanation of symbols

１ 圧電体
２、３ 電極
２Ａ 開口部 1 Piezoelectric body 2, 3 Electrode 2A Opening

Claims (3)

振動により超音波を発生する板状の圧電体と、この圧電体の上面および下面にそれぞれ設けられ、この圧電体を駆動するための電圧が加えられる電極とを具備する超音波振動子において、
前記少なくとも一方の電極に、少なくとも１以上の開口部を設けたことを特徴とする超音波振動子。 In an ultrasonic transducer comprising: a plate-like piezoelectric body that generates ultrasonic waves by vibration; and an electrode that is provided on each of the upper and lower surfaces of the piezoelectric body and to which a voltage is applied to drive the piezoelectric body.
An ultrasonic transducer comprising at least one or more openings in the at least one electrode. 前記上下面の電極は印刷によって設けられ、前記開口部は印刷の際に設けられ、電極が印刷されない領域であることを特徴とする請求項１に記載の超音波振動子。   The ultrasonic transducer according to claim 1, wherein the upper and lower electrodes are provided by printing, the opening is provided at the time of printing, and the electrode is not printed. 前記開口部の形状は円形、楕円、長円、多角形、または線状であることを特徴とする請求項１または２に記載の超音波振動子。   The ultrasonic transducer according to claim 1, wherein the shape of the opening is a circle, an ellipse, an ellipse, a polygon, or a line.
JP2005305203A 2005-10-20 2005-10-20 Ultrasonic wave vibrator Pending JP2007115866A (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1127798A (en) * 1997-07-04 1999-01-29 S C:Kk Method for generating ultrasonic vibration
JP2002084596A (en) * 2000-09-07 2002-03-22 Shibaura Mechatronics Corp Ultrasonic oscillator and its manufacturing method

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1127798A (en) * 1997-07-04 1999-01-29 S C:Kk Method for generating ultrasonic vibration
JP2002084596A (en) * 2000-09-07 2002-03-22 Shibaura Mechatronics Corp Ultrasonic oscillator and its manufacturing method

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