【発明の詳細な説明】
本発明は超音波振動子に係り、特に加湿器用お
よび灯油燃焼器用の霧化振動子に関する。
最近では健康管理上、室内の湿度を調整する超
音波加湿器が広く使用されている。即ち、電歪振
動子を用いた超音波加湿器は音が静かで電気的に
安定な上、水温を上昇させる事なく、微細な噴霧
を容易に得られるためである。
また、これらの電歪振動子は灯油の霧化現象を
利用した灯油燃焼機器にも応用されつつある。こ
の場合霧化粒子が小さいため、ほぼ完全燃焼に近
くなり燃焼効率が上り、さらに瞬間点火もしくは
消火や燃焼量のコントロールが容易となる等の利
点を有していた。
従来、上記の如き電歪振動子として以下の如き
ものが用いられていた。
例えば第１図に示す如く電歪振動子素体１の一
方の面には廻り込み電極２が、また他方の面には
円状電極３が設けられており、前記廻り込み電極
２と円状電極３との間に電圧を印加することによ
り、電歪振動子素体に分極処理を施し製造してい
た。しかしながら上記の如く分極処理を施して製
造した電歪振動子１０においては加湿器の発生霧
化量は高々400〜500c.c.／時間が限度であり、実用
上充分なものとは言えなかつた。
本発明は上記の点に鑑み、霧化効率の優れた霧
化振動子を提供することを目的とする。
本発明は厚み振動結合係数Ktとポアソン比σ
との積Kt・σが0.153以上の値を有する電歪振動
子を用いた霧化振動子である。つまり本発明者等
は霧化効率を向上させるために電歪振動子につい
て研究した結果、厚み振動結合係数Ktとポアソ
ン比σとの積Kt・σが0.153以上の場合で、特に
厚み振動結合係数Ktが0.47以上の際霧化効率が著
しく改善される事を見い出した。
以下本発明を実施例により詳細に説明する。第
２図は本発明における実験に用いた電歪振動子１
０を示し第２図ａは平面図、第２図ｂは断面図を
それぞれ示す。圧電材料により形成された電歪振
動子素体１の一方の面には、全体に亘つて主電極
５を設け、他の面には円状の部分電極６およびこ
の部分電極６から所要のギヤツプ９を隔てリング
状電極７を同心円状に設ける。しかして部分電極
６とリング状電極７を同電位にし、主電極５との
間に高電圧を印加して、電歪振動子素体１内を厚
み方向に分極すると、矢印８の如く全体が一様に
厚み方向に分極され、電歪振動子１０が得られ
る。
つまり第２図の如き構造の電歪振動子において
は分極方向８が厚み方向に一定となり、動作時に
おける振動歪みが一様となる。
なお上記電歪振動子は、第３図に示す如く霧化
槽１１に取り付けられ、パワーアンプ１２からの
印加電圧により液体１３を霧化した後、送風フア
ン１４で外部に放出する。
例えばポアソン比σおよび厚み振動結合係数
Ktを変えた各種電歪振動子を用いた場合の霧化
量Ｑを表に示す。
【表】
第４図はたとえばPbTiO3−PbZrO3−Pb（Co
1/2Ｗ1/2）O3系圧電材料に於てこの系の組成を
変化せしめ、それぞれKtあるいはポアソン比σ
の異なる材料について第２図に示す様な電極形状
を有し外径20φ、部分電極径14φ、周波数1.65M
Hzの霧化振動子に高周波電力約17Wを印加し、水
に対する霧化量を測定したものである。第４図中
曲線ＡはKt・σの積を曲線Ｂは霧化量Ｑを曲線
ＣはKtを示してある。第４図から判る様にKtが
大でも、Kt・σの積が小さい場合は霧化量Ｑも
小さく、Kt・σの積が大きい程霧化量Ｑが大と
なつている。本発明に於て、Kt＝0.47、Kt・σ
の積を0.153に選んだ理由は、Kt・σの積がこの
値以下の場合霧化量Ｑは従来程度の値であり、こ
の値以上の時従来のものと比較して特性が大巾に
向上するためである。 DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic transducer, and more particularly to an atomizing transducer for use in humidifiers and kerosene burners. Recently, ultrasonic humidifiers that adjust indoor humidity have been widely used for health management purposes. That is, an ultrasonic humidifier using an electrostrictive vibrator is quiet and electrically stable, and can easily produce a fine mist without raising the water temperature. These electrostrictive vibrators are also being applied to kerosene-burning equipment that utilizes the atomization phenomenon of kerosene. In this case, since the atomized particles are small, combustion efficiency is increased due to almost complete combustion, and furthermore, it has advantages such as instantaneous ignition or extinguishing and easy control of combustion amount. Conventionally, the following types of electrostrictive vibrators have been used as the above-mentioned electrostrictive vibrators. For example, as shown in FIG. 1, a wraparound electrode 2 is provided on one surface of the electrostrictive vibrator element 1, and a circular electrode 3 is provided on the other surface. The electrostrictive vibrator element was manufactured by applying a voltage between it and the electrode 3 to perform polarization treatment. However, in the electrostrictive vibrator 10 manufactured by polarization treatment as described above, the amount of atomization generated by the humidifier is limited to 400 to 500 c.c./hour, which cannot be said to be sufficient for practical use. . In view of the above points, an object of the present invention is to provide an atomization vibrator with excellent atomization efficiency. The present invention is based on the thickness vibration coupling coefficient Kt and Poisson's ratio σ.
This is an atomization oscillator using an electrostrictive oscillator whose product Kt・σ is 0.153 or more. In other words, as a result of research on electrostrictive oscillators to improve atomization efficiency, the present inventors found that when the product Kt・σ of the thickness vibration coupling coefficient Kt and Poisson's ratio σ is 0.153 or more, the thickness vibration coupling coefficient It was found that the atomization efficiency was significantly improved when Kt was 0.47 or more. The present invention will be explained in detail below with reference to Examples. Figure 2 shows the electrostrictive vibrator 1 used in the experiment of the present invention.
0, FIG. 2a shows a plan view, and FIG. 2b shows a sectional view. A main electrode 5 is provided over the entirety of one surface of the electrostrictive vibrator element 1 formed of a piezoelectric material, and a circular partial electrode 6 and a required gap are formed from the partial electrode 6 on the other surface. Ring-shaped electrodes 7 are provided concentrically with 9 space apart. When the partial electrode 6 and the ring-shaped electrode 7 are set at the same potential and a high voltage is applied between them and the main electrode 5 to polarize the inside of the electrostrictive vibrator element 1 in the thickness direction, the entire body is polarized as shown by the arrow 8. The electrostrictive vibrator 10 is obtained by being uniformly polarized in the thickness direction. In other words, in the electrostrictive vibrator having the structure as shown in FIG. 2, the polarization direction 8 is constant in the thickness direction, and the vibration distortion during operation is uniform. The electrostrictive vibrator is attached to an atomization tank 11 as shown in FIG. 3, and after atomizing the liquid 13 by applying voltage from a power amplifier 12, it is discharged to the outside by a blower fan 14. For example, Poisson's ratio σ and thickness vibrational coupling coefficient
The table shows the atomization amount Q when using various electrostrictive vibrators with different Kt. [Table] Figure 4 shows, for example, PbTiO 3 −PbZrO 3 −Pb(Co
1/2W1/2)O In the 3 -based piezoelectric material, the composition of this system is changed, and the Kt or Poisson's ratio σ is changed, respectively.
It has an electrode shape as shown in Figure 2 for different materials, outer diameter 20φ, partial electrode diameter 14φ, frequency 1.65M.
Approximately 17 W of high-frequency power was applied to a Hz atomization oscillator, and the amount of atomization of water was measured. In FIG. 4, curve A shows the product of Kt·σ, curve B shows the atomization amount Q, and curve C shows Kt. As can be seen from FIG. 4, even if Kt is large, if the product of Kt and σ is small, the atomization amount Q is also small, and the larger the product of Kt and σ is, the larger the atomization amount Q is. In the present invention, Kt=0.47, Kt・σ
The reason for choosing the product of 0.153 is that when the product of Kt and σ is below this value, the atomization amount Q is about the same as before, and when it is above this value, the characteristics are significantly different compared to the conventional one. The purpose is to improve.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図及び第２図の電歪振動子の構成例を示す
断面図および平面図、第３図は本発明に用いた実
験装置を示す断面図、
１……電歪振動子素体、１０……電歪振動子、
１１……霧化槽、１４……送風フアン。
第４図は（厚み振動結合係数Kt）×（ポアソン
比σ）と霧化量Ｑとの関係を示す曲線図。
1 and 2 are cross-sectional views and plan views showing configuration examples of the electrostrictive vibrator, and FIG. 3 is a cross-sectional view showing an experimental apparatus used in the present invention. 1... Electrostrictive vibrator element body, 10 ...Electrostrictive vibrator,
11...Atomization tank, 14...Blower fan. FIG. 4 is a curve diagram showing the relationship between (thickness vibration coupling coefficient Kt)×(Poisson's ratio σ) and atomization amount Q.