JP3754892B2

JP3754892B2 - Piezoelectric resonator for atomizer

Info

Publication number: JP3754892B2
Application number: JP2000366204A
Authority: JP
Inventors: 浩信黒山
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2000-11-30
Filing date: 2000-11-30
Publication date: 2006-03-15
Anticipated expiration: 2020-11-30
Also published as: JP2002166226A

Description

【０００１】
【発明の属する技術分野】
本発明は、円環状の圧電基板の両主面に形成した励振電極間に高周波電圧を印加し、円環状の圧電基板の内周側主面に半田接合した微細な穴の開いた振動板を超音波振動させることによって、この微細な穴から芳香剤などの液体を霧化する霧化装置用圧電共振器に関する。
【０００２】
【従来の技術及びその課題】
圧電振動子を使った超音波霧化装置としては、ボルト締ランジュバン型振動子を応用した超音波霧化装置およびネブライザーが挙げられる。ボルト締ランジュバン型振動子による霧化装置は数１０ｋＨｚという周波数の超音波を利用したもので、多量の霧を発生させるという長所を有するが、構造が複雑で素子が大がかりであるという短所をあわせもっている。
【０００３】
一方、ネブライザーは、容器の底などに圧電振動子を取り付けて、ＭＨｚ領域の超音波振動を発生させ、容器内の液面に微細気泡を発生させ、液面からの霧化を促すもので、粒子が微小で均一性に優れるという長所を有するものの、霧化効率が悪く、小電力で多量の霧を発生させるのが難しいという短所をもつ。
【０００４】
このような技術に対し特許第２，５９９，８４４号には、中央が厚み方向に貫通した円環状の圧電共振器を用い、その貫通孔を覆い、かつ、中央部に微細な穴を多数個あけた振動板を取り付けて複合振動体を形成し、その振動系の共振周波数に近い信号で駆動することにより、小型で霧化効率の高い超音波霧化装置を得ることができることが開示されている。
【０００５】
例えば、振動板は厚みが５０μｍほどのニッケル材からなり、直径が５．５ｍｍで中央部がドーム状に成型され、ドームの頂部周辺には断面がテーパ状の細孔を多数形成したものでその外周は圧電振動子の一方主面に半田で接合される。
【０００６】
ここで円環状の圧電共振器は、たとえば外径が１０ｍｍ、内径が４．５ｍｍ、厚みが０．５ｍｍていどの円環状圧電基板の両主面に、金、銀やニッケルなどの励振電極を全面に被着形成したものである。
【０００７】
しかしこの構造で圧電基板を形成しようとすると、両主面全面に形成された励振電極間に１〜２ｋＶという高い電圧を印加して圧電特性を付与する必要があるが、内外周端面で放電を起こしやすく、その衝撃で圧電共振器が破壊されるなどの事故を発生しやすい。
【０００８】
このような放電事故を防止するため、図６（ａ）〜（ｃ）に示すように、量産上の電極パターンはスクリーン印刷法やマスクを使った蒸着法等によって圧電基板４２の内外周寸法に対して内側になるように、すなわち圧電基板の外周と電極の外周間に無電極領域4６を確保し、圧電基板の内周と電極内周間にも同様に無電極領域４７を設ける必要がある。
【０００９】
この無電極領域４６，４７は通常０．１〜１ｍｍ前後で、電極形成時の圧電基板と電極パターンのズレや、ズレによって生じる電極材料の側壁への回り込みにより両主面の電極間でのショートや、分極時のスパーク、経時変化によるマイグレーションが発生するのを防止している。すなわち信頼性の確保を行うものである。
【００１０】
しかしながら、近年の装置の小型化により、上述のような無電極領域４６，４７を形成することで励振電極の幅が狭くなり、圧電基板の中に圧電特性に関与しない領域が発生すればするほど霧化効率を低下するという問題点を生じた。
【００１１】
また、図５（ａ）（ｂ）に示すように圧電基板４２と振動板４４の接合を半田４５で行う場合、圧電基板４２の内径部に半田付け不可能な圧電基板の無電極領域４７があるため電極膜厚と半田層の厚みにより発生する１００μｍ程度の隙間４９が生じていた。
【００１２】
この隙間が存在することによって、圧電基板と振動板からなる圧電共振器の共振特性が悪化し、また液体が隙間に浸透することにより性能の低下が生じるという問題が発生する。
【００１３】
本発明は上述した問題点に鑑みて案出されたものであり、霧化効率の高い圧電共振器でありながら、量産性が高くまた信頼性の高い圧電共振器を提供することを目的とする。
【００１４】
【課題を解決するための手段】
上述の目的を達成するために本発明は、中央が厚み方向に貫通した円環状の圧電基板と、該圧電基板の両主面に形成された一対の励振電極と、前記圧電基板の一方主面側に貫通孔を覆うように配設され、かつ、中央部に細孔を設けた振動板とを有し、前記振動板の一方主面側と前記圧電基板の一方主面に形成した前記励振電極とが半田を介して接続された霧化装置用圧電共振器において、前記圧電基板の一方主面に形成された前記励振電極は、前記圧電基板の一方主面と同寸法に形成されていると共に、前記圧電基板の他方主面に形成された前記励振電極は、前記圧電基板の他方主面の外周側領域と内周側領域とを除く領域に前記圧電基板の他方主面の寸法より小さく形成されており、前記振動板は、中央部が前記貫通孔に対向し、かつ、頂部に前記細孔を有するドーム状に成型されると共に、前記圧電基板の一方主面の前記励振電極の内周と前記振動板の外周との間が前記半田を介して接続され、前記圧電基板の直径が広がったり縮んだりする運動によりドーム部を上下させる運動を生じて前記圧電基板の前記貫通孔に供給される液体を前記細孔から放出することを特徴とする霧化装置用圧電共振器を提供する。
【００１５】
本発明の構成によれば、圧電基板の一方主面の全領域に励振電極が形成され、他方主面には外周側領域と内周側領域を除く領域に励振電極が形成されているので、圧電特性が向上して振動板の振動を助けることができ、霧化効率を上げることができるものである。これにより両方主面に全面電極を形成した場合と差のない霧化装置用の圧電共振器を提供することができる。
【００１６】
このような作用は以下のようにして起こることが推定される。即ち、圧電基板の一方主面の全領域に形成した励振電極周辺は大きな伸び縮みをしようとし、他方主面の無電極領域を持った励振電極の周辺では相対的に小さな変形にとどまるため、圧電基板の厚み方向で伸縮量に差が生じ、圧電基板は基板主面に対して凹凸の変形運動を発生させ、結果として内周側に取り付けられた振動板の振動を助けることになり霧化効率を高めるものである。
【００１７】
また、圧電基板の一方主面に形成された励振電極の内周側に前記半田を接続したことにより、圧電基板と振動板に隙間が形成されないため、波形分割がなく、また霧化したい液を付着させたときに共振点がシフトしない良好な振動特性を得ることができる。
【００１８】
結局、圧電共振器の他方主面に無電極領域を持った圧電共振器にすることで、圧電基板への電極形成を容易にするとともに、分極操作において圧電基板を破損する事故を防止し、量産性の高い圧電共振器を提供することができる。
【００１９】
【発明の実施の形態】
本発明の実施の形態を図を用いて説明する。
図１は本発明の霧化装置用圧電共振器を説明する図であり、（ａ）はその平面図、（ｂ）は（ａ）に示すＡ−Ａ線断面図である。図2は霧化装置用圧電共振器に用いる圧電共振子を説明する3面図であり、（ａ）はその平面図、（ｂ）は（ａ）のＢ−Ｂ線断面図、（ｃ）は底面図である。
【００２０】
本発明の霧化装置用圧電共振器１は、円環状の圧電基板１２の両主面に励振電極１１，１３が形成された圧電振動子１０と、圧電基板１２の一方主面側に振動板１４とを配置し、その振動板１４と振動電極１１とが半田１５により固着して構成されている。図２に示すように円環状の圧電基板１２は外径１０ｍｍ、内径４．５ｍｍ、厚み０．５ｍｍで、その両面の電極は金、銀、ニッケル等の電極材料を用いて厚膜法による印刷焼付けや、蒸着法などによって形成されている。形成される振動電極１１は、圧電基板１２の一方主面に形成され、この面に振動板１４が半田１５により固着される。振動電極１１は円環状の圧電基板１２の一方主面の全面に形成される。即ち圧電基板１２の一方主面と同寸法の励振電極１１が形成されている。また、励振電極１３は圧電基板１２の他方主面に圧電基板１２の寸法より小さく形成されている、圧電基板１２の他方主面の外周側及び内周側には長さが０．１ｍｍ〜１．０ｍｍの無電極領域１６，１７が設けられている。この無電極領域１６，１７は圧電基板１２の厚み１８によって異なる。これは分極時の印加電圧が圧電基板１２の厚みによって異なるためで分極時のスパーク防止のため、厚み１８が薄いと分極電圧も低く無電極領域を小さくし、逆に厚み１８が厚くなると分極電圧が高くなることから無電極領域を大きくする必要がある。圧電基板１２の０．５ｍｍ厚みに対しては無電極領域１６,１７を０．５ｍｍにとる。
【００２１】
振動板１４は厚みが５０μほどのニッケル材からなり、直径が５．５ｍｍで中央部がドーム状に成型され、ドームの頂部周辺には断面がテーパ状の細孔（不図示）を多数形成したものである。
【００２２】
図１（ｂ）に示すように、圧電振動子１０にその貫通孔を覆うように振動板１４を配置して、圧電振動子１０の振動電極１１と振動板１４の外周表面とを半田１５で固着させた構造が示される。半田１５を接続する位置としては圧電基板１２の一方主面に形成された励振電極１１の内周側から外周側にかけて形成されている。
【００２３】
これにより振動板１４の固着側の振動電極１１内周側は圧電基板１２と同寸法のため振動板１４と圧電基板１２間に無電極領域が生じなく大きな共振を得ることができ圧電基板１２の振動を効率よく振動板１４に伝達することができる。また、圧電基板１２と振動板１４との間に隙間が存在せず使用時の液体の浸透がないため、共振特性の変化がなく、霧化性能の低下を防ぐことが出来る。
【００２４】
このように構成された霧化装置用圧電共振器の動作については、圧電振動子１０の両主面に形成された励振電極１１，１３間に高周波電圧を印加すると、圧電基板１２は直径が広がったり縮んだりする運動を起こす。その運動は振動板１４に伝えられて振動板１４の中央に形成されているドーム部を上下させる運動を生じる。これによりドーム内側（圧電基板１２の貫通孔）に保液材から供給される芳香剤などの液体が０．０１ｍｍ程度の細孔から放出されて霧化されてゆく。また圧電基板１２の両主面に幅の異なる励振電極１１，１３があるため、両主面の伸縮度合いが異なり内周部が主面に対して面方向に前後する振動を発生し、振動板１４の前後運動を助長して霧化効率を高めることができる。
【００２５】
ここで、霧化器の詳細は示していないが、液体供給手段としてスポンジやフェルトなどの保液材を用いて振動板１４の下面に液体が供給される。
なお、圧電基板の両主面に無電極領域を持った従来構造の圧電基板を用いても、振動板との隙間４９を埋める材料を付与しても類似の効果を得ることができる。たとえばガラス粒子や金属粒子をフィラーとして含むエポキシ接着剤やフェノール系接着剤を塗布して硬化させることで、共振波形の分割を抑えることができる。ただしこの場合は芳香剤の中に含まれる有機溶剤により接着強度が低下しないことを十分に確認する必要がある。
【００２６】
図３に本発明の霧化装置用圧電共振器１と励振電極１１の内周部と圧電基板１２の一方主面の内周部との隙間が大きくなったときの共振特性が示される。縦軸がインピーダンスで横軸が周波数である。隙間がない場合（Ａ）は１４５ｋＨｚ付近に共振が見られるが、無電極領域４６，４７が０．３ｍｍの場合（Ｂ）、０．５ｍｍの場合（Ｃ）と増加すると、（Ｂ）、（Ｃ）に示すように共振波形が分割されるとともに、共振波形が小さくなり、主共振点（１４２ｋＨｚ付近）における共振抵抗の値が高くなって所定の入力に対する霧化効率が落ちる事がわかる。また共振周波数が接近して複数あるため周波数飛びが発生し、外乱で発振しなくなるなどのミスマッチを起こし、やはり霧化効率が低下している。
【００２７】
また図４に霧化装置用圧電共振器１に液体が付着した場合の影響を見ている。図５、６で記載した隙間４９のない本発明の構成の場合（Ａ）は殆ど影響がないのに対して隙間４９を大きくとった場合（Ｂ）の共振波形は低周波側に大きくシフトすることがわかる。液体としてアルコールが付着したときの状況を示すが液付着の有無により影響を受けている。このとき圧電基板と電極間の無電極領域４６，４７が０．５ｍｍ時のアルコール付着時の共振特性の変動で、実線は初期値、鎖線はアルコール付着１時間後を示す。
【００２８】
図４より、圧電振動子１０と振動板１４間に隙間が生じていることで液が浸透し、特性が変動していることがわかる。共振周波数がずれると所定の駆動用の発振回路からの信号と合わず十分な霧化効率を達成することができない。
【００２９】
【発明の効果】
本発明の霧化装置用圧電共振器は、円環状の圧電基板の一方主面全域に励振電極を形成すると共に、他方主面に周囲に無電極領域をもつ励振電極を形成することで、圧電振動子の圧電特性が向上して振動板の振動を助けることができ、霧化効率を上げることができるものである。これにより両方主面に全面電極を形成した場合と差のない霧化装置用の圧電共振器を提供することができる。
【００３０】
また、圧電基板の他方主面には、十分な無電極領域があるため、励振電極を形成しても高電圧を印加する分極工程で不良発生を防止することができる。従って、霧化装置用圧電共振器の加工が容易で、高い歩留まりで製造することができるため安価に圧電共振器を量産することができる。また特性面でも小電力で高い霧化効率を得ることができる。
【００３１】
また、圧電基板の一方主面全域に形成した励振電極の内周側から外周側にかけて半田領域を形成して振動板を取り付けるという構造を採用しているので、圧電基板と振動板に隙間が形成されないため、波形分割がなく、また霧化したい液を付着させたときに共振点がシフトしない良好な振動特性を得た霧化装置用圧電共振器を提供することができる。
【図面の簡単な説明】
【図１】本発明の霧化装置用圧電共振器であり（ａ）は正面図、（ｂ）は（ａ）のＡ−Ａ線断面図である。
【図２】本発明の圧電振動子を示す３面図であり、（ａ）はその平面図、（ｂ）は（ａ）のＢ−Ｂ線断面図、（ｃ）は底面図である。
【図３】（Ａ）は圧電基板と振動板との間に隙間が無い場合、（Ｂ）隙間が０．３ｍｍの場合、（Ｃ）０．５ｍｍの場合の共振特性を説明する図である。
【図４】本発明の霧化装置用圧電共振器に液体が付着した場合の共振特性の影響を示し、（Ａ）は隙間が無い場合、（Ｂ）は隙間を形成した場合を示す。
【図５】従来の霧化装置用圧電共振器であり（ａ）は正面図、（ｂ）は中央縦断面図である。
【図６】従来の圧電振動子を示す３面図であり、（ａ）はその平面図、（ｂ）は中央縦断面図、（ｃ）は底面図である。
【符号の説明】
１１，１３：励振電極
１２：圧電基板
１４：振動板
１５：半田
１６，１７：無電極領域[0001]
BACKGROUND OF THE INVENTION
The present invention provides a vibrating plate having fine holes that is applied with a high frequency voltage between excitation electrodes formed on both main surfaces of an annular piezoelectric substrate and soldered to the inner peripheral side main surface of the annular piezoelectric substrate. The present invention relates to a piezoelectric resonator for an atomizing device that atomizes a liquid such as a fragrance from this fine hole by ultrasonic vibration.
[0002]
[Prior art and problems]
Examples of the ultrasonic atomizer using a piezoelectric vibrator include an ultrasonic atomizer and a nebulizer using a bolt tightened Langevin type vibrator. An atomizer using a bolt-clamped Langevin type transducer uses ultrasonic waves with a frequency of several tens of kHz and has the advantage of generating a large amount of fog, but also has the disadvantage that the structure is complicated and the element is large. I have.
[0003]
On the other hand, a nebulizer attaches a piezoelectric vibrator to the bottom of a container, etc., generates ultrasonic vibrations in the MHz range, generates fine bubbles on the liquid level in the container, and promotes atomization from the liquid level. Although it has the advantage that the particles are fine and excellent in uniformity, it has the disadvantage that the atomization efficiency is poor and it is difficult to generate a large amount of fog with low power.
[0004]
In contrast to this technology, Patent No. 2,599,844 uses an annular piezoelectric resonator whose center penetrates in the thickness direction, covers the through-hole, and has many fine holes in the center. It is disclosed that a small-sized ultrasonic atomizing device with high atomization efficiency can be obtained by attaching a diaphragm that is opened to form a composite vibrator and driving it with a signal close to the resonance frequency of the vibration system. Yes.
[0005]
For example, the diaphragm thickness being nickel material as 50.mu. m, diameter is molded central portion in a dome shape at 5.5 mm, the peripheral top of the dome in which cross section is formed a number of tapered pores The outer periphery is joined to one main surface of the piezoelectric vibrator with solder.
[0006]
Wherein an annular piezoelectric resonator, for example, an outer diameter of 10 mm, an inner diameter of 4.5 mm, on both main surfaces of the annular piezoelectric substrate having a thickness of 0.5mm approximately, gold, excited vibronic electrode such as silver or nickel Is deposited on the entire surface.
[0007]
However, when attempting to form the piezoelectric substrate in this structure, it is necessary to impart piezoelectric properties by applying a high voltage of 1~2kV the excitation vibronic machining gap formed on both main surfaces entirely, but the inner and outer peripheral edge surfaces Electric discharge easily occurs, and accidents such as destruction of the piezoelectric resonator due to the impact are likely to occur.
[0008]
In order to prevent such a discharge accident, as shown in FIGS. 6A to 6C, the electrode pattern for mass production is made to have an inner and outer peripheral dimension of the piezoelectric substrate 42 by a screen printing method or a vapor deposition method using a mask. On the other hand, it is necessary to secure an electrodeless region 46 between the outer periphery of the piezoelectric substrate and the outer periphery of the electrode, and similarly provide an electrodeless region 47 between the inner periphery of the piezoelectric substrate and the inner periphery of the electrode. .
[0009]
The electrodeless regions 46 and 47 are usually around 0.1 to 1 mm, and a short circuit between the electrodes on both main surfaces due to the displacement of the piezoelectric substrate and the electrode pattern at the time of electrode formation and the wraparound of the electrode material caused by the displacement. Further, it is possible to prevent the occurrence of migration due to sparks during polarization and changes with time. That is, reliability is ensured.
[0010]
However, due to the recent downsizing of the apparatus, the width of the excitation electrode becomes narrower by forming the electrodeless regions 46 and 47 as described above, and the more the region that is not related to the piezoelectric characteristics is generated in the piezoelectric substrate. The problem of reducing atomization efficiency was caused.
[0011]
5A and 5B, when the piezoelectric substrate 42 and the diaphragm 44 are joined with the solder 45, the electrodeless region 47 of the piezoelectric substrate that cannot be soldered to the inner diameter portion of the piezoelectric substrate 42 is provided. Therefore, a gap 49 of about 100 μm generated depending on the electrode film thickness and the solder layer thickness was generated.
[0012]
The presence of this gap deteriorates the resonance characteristics of the piezoelectric resonator composed of the piezoelectric substrate and the vibration plate, and causes a problem that the performance deteriorates due to the penetration of liquid into the gap.
[0013]
The present invention has been devised in view of the above-described problems, and an object of the present invention is to provide a piezoelectric resonator having high productivity and high reliability while being a piezoelectric resonator having high atomization efficiency. .
[0014]
[Means for Solving the Problems]
The present invention in order to achieve the above object, an annular piezoelectric substrate center was penetrated in a thickness direction, a pair of excitation vibronic electrode formed on both main surfaces of the piezoelectric substrate, one of said piezoelectric substrate It is disposed so as to cover the transmural hole in the main surface side, and, and a vibration plate provided with pores in the central portion, formed on the one major surface side of the vibrating plate one main surface of the piezoelectric substrate in the atomizing apparatus for a piezoelectric resonator in which the and the excitation electrode are connected via the solder, the excitation electrodes formed on one main surface of the piezoelectric substrate is formed on one main surface and the dimension of the piezoelectric substrate is Rutotomoni, the excitation electrodes formed on the other main surface of the piezoelectric substrate, the other main surface of the piezoelectric substrate in the region except the outer peripheral side region and the inner peripheral side region of the other main surface of the piezoelectric substrate is formed smaller than the dimension, the diaphragm has a central portion facing the through-hole, and the top The inner periphery of the excitation electrode on one main surface of the piezoelectric substrate and the outer periphery of the diaphragm are connected via the solder, and are formed into a dome shape having the pores on the piezoelectric substrate. A piezoelectric resonator for an atomizing device, characterized in that a liquid that is supplied to the through-hole of the piezoelectric substrate is released from the fine hole by moving the dome part up and down by a movement in which the diameter expands or contracts. provide.
[0015]
According to the configuration of the present invention, the excitation electrode is formed in the entire region of the one main surface of the piezoelectric substrate, and the excitation electrode is formed in the region other than the outer peripheral region and the inner peripheral region on the other main surface. The piezoelectric characteristics can be improved to help the vibration of the diaphragm, and the atomization efficiency can be increased. Accordingly, it is possible to provide a piezoelectric resonator for an atomizing device that is not different from the case where full-surface electrodes are formed on both main surfaces.
[0016]
It is presumed that such an action occurs as follows. That is, the area around the excitation electrode formed on the entire area of one main surface of the piezoelectric substrate tends to expand and contract, while the area around the excitation electrode having the electrode area on the other main surface remains relatively small. There is a difference in the amount of expansion and contraction in the thickness direction of the substrate, and the piezoelectric substrate generates uneven deformation movement with respect to the main surface of the substrate. It is what raises.
[0017]
In addition, since the solder is connected to the inner peripheral side of the excitation electrode formed on one main surface of the piezoelectric substrate, a gap is not formed between the piezoelectric substrate and the diaphragm, so there is no waveform division and the liquid to be atomized Good vibration characteristics in which the resonance point does not shift when adhered can be obtained.
[0018]
After all, by making a piezoelectric resonator with an electrodeless area on the other main surface of the piezoelectric resonator, it is easy to form electrodes on the piezoelectric substrate, and prevent accidents that damage the piezoelectric substrate during polarization operation. A high-performance piezoelectric resonator can be provided.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
1A and 1B are views for explaining a piezoelectric resonator for an atomizer according to the present invention, in which FIG. 1A is a plan view thereof, and FIG. 1B is a cross-sectional view taken along line AA shown in FIG. FIG. 2 is a three-side view for explaining a piezoelectric resonator used in a piezoelectric resonator for an atomizer, (a) is a plan view thereof, (b) is a sectional view taken along line BB in (a), and (c). Is a bottom view.
[0020]
The piezoelectric resonator 1 for an atomizing device according to the present invention includes a piezoelectric vibrator 10 having excitation electrodes 11 and 13 formed on both main surfaces of an annular piezoelectric substrate 12 and a diaphragm on one main surface side of the piezoelectric substrate 12. 14, and the diaphragm 14 and the vibrating electrode 11 are fixed by solder 15 . As shown in FIG. 2, the annular piezoelectric substrate 12 has an outer diameter of 10 mm, an inner diameter of 4.5 mm, and a thickness of 0.5 mm, and electrodes on both sides are printed by a thick film method using an electrode material such as gold, silver, or nickel. It is formed by baking or vapor deposition. The formed vibration electrode 11 is formed on one main surface of the piezoelectric substrate 12, and the vibration plate 14 is fixed to the surface by solder 15 . The vibration electrode 11 is formed on the entire surface of one main surface of the annular piezoelectric substrate 12. That is, the excitation electrode 11 having the same dimensions as the one main surface of the piezoelectric substrate 12 is formed. The excitation electrode 13 is formed on the other main surface of the piezoelectric substrate 12 to be smaller than the dimension of the piezoelectric substrate 12. The length is 0.1 mm to 1 mm on the outer peripheral side and inner peripheral side of the other main surface of the piezoelectric substrate 12. 0 mm electrodeless regions 16 and 17 are provided. The electrodeless regions 16 and 17 differ depending on the thickness 18 of the piezoelectric substrate 12. This is because the applied voltage at the time of polarization varies depending on the thickness of the piezoelectric substrate 12 , and in order to prevent sparks at the time of polarization, the polarization voltage is low and the non-electrode region is reduced when the thickness 18 is thin. Therefore, it is necessary to enlarge the electrodeless region. For the 0.5 mm thickness of the piezoelectric substrate 12, the electrodeless regions 16 and 17 are set to 0.5 mm.
[0021]
The diaphragm 14 is made of a nickel material having a thickness of about 50 μm, has a diameter of 5.5 mm, a central portion is molded into a dome shape, and a large number of pores (not shown) having a tapered section are formed around the top of the dome. Is.
[0022]
As shown in FIG. 1B, a diaphragm 14 is disposed on the piezoelectric vibrator 10 so as to cover the through hole, and the vibration electrode 11 of the piezoelectric vibrator 10 and the outer peripheral surface of the diaphragm 14 are connected with solder 15. The fixed structure is shown. The position where the solder 15 is connected is formed from the inner peripheral side to the outer peripheral side of the excitation electrode 11 formed on one main surface of the piezoelectric substrate 12.
[0023]
As a result, the inner peripheral side of the vibration electrode 11 on the fixed side of the vibration plate 14 has the same dimensions as the piezoelectric substrate 12 , so that a large resonance can be obtained without generating an electrodeless region between the vibration plate 14 and the piezoelectric substrate 12. Vibration can be efficiently transmitted to the diaphragm 14. In addition, since there is no gap between the piezoelectric substrate 12 and the diaphragm 14 and there is no liquid permeation during use, there is no change in the resonance characteristics, and a reduction in atomization performance can be prevented.
[0024]
The operation of the thus configured atomizer piezoelectric resonator, by applying a high frequency voltage between the excitation electrodes 11 and 13 formed on both main surfaces of the piezoelectric vibrator 10, piezoelectric substrate 12 is expanded in diameter Cause an exercise that shrinks or shrinks. The movement is transmitted to the diaphragm 14 to cause a movement of moving up and down the dome formed at the center of the diaphragm 14. As a result, a liquid such as a fragrance supplied from the liquid retaining material is discharged from the pores of about 0.01 mm into the inside of the dome (through hole of the piezoelectric substrate 12) and atomized. In addition, since both main surfaces of the piezoelectric substrate 12 have the excitation electrodes 11 and 13 having different widths, the expansion and contraction degrees of both main surfaces are different, and vibrations are generated in which the inner peripheral portion moves back and forth with respect to the main surface. It is possible to enhance the atomization efficiency by promoting the back-and-forth motion of 14 .
[0025]
Although details of the atomizer are not shown here, the liquid is supplied to the lower surface of the diaphragm 14 using a liquid retaining material such as sponge or felt as the liquid supply means.
Similar effects can be obtained by using a conventional piezoelectric substrate having electrodeless regions on both principal surfaces of the piezoelectric substrate, or by providing a material that fills the gap 49 with the diaphragm. For example, the division of the resonance waveform can be suppressed by applying and curing an epoxy adhesive or a phenol-based adhesive containing glass particles or metal particles as a filler. However, in this case, it is necessary to sufficiently confirm that the adhesive strength is not lowered by the organic solvent contained in the fragrance.
[0026]
Resonant characteristics when the gap is increased for atomizer piezoelectric resonator 1 and the inner peripheral portion and the inner peripheral portion of the one main surface of the piezoelectric substrate 12 of the excitation electrodes 11 of the present invention is shown in FIG. The vertical axis is impedance and the horizontal axis is frequency. When there is no gap (A), resonance is observed near 145 kHz, but when the electrodeless regions 46 and 47 are 0.3 mm (B) and 0.5 mm (C), the increase is (B), ( As shown in C), the resonance waveform is divided, the resonance waveform becomes smaller, the value of the resonance resistance at the main resonance point (near 142 kHz) becomes higher, and the atomization efficiency with respect to a predetermined input decreases. Moreover, since there are a plurality of resonance frequencies close to each other, a frequency jump occurs, causing a mismatch such as no oscillation due to a disturbance, and the atomization efficiency is also lowered.
[0027]
Also, FIG. 4 shows the effect when liquid adheres to the atomizer piezoelectric resonator 1. In the case of the configuration of the present invention without the gap 49 described in FIGS. 5 and 6, there is almost no influence, whereas when the gap 49 is made large, the resonance waveform is greatly shifted to the low frequency side. I understand that. This shows the situation when alcohol is attached as a liquid, but it is affected by the presence or absence of liquid adhesion. At this time, the non-electrode regions 46 and 47 between the piezoelectric substrate and the electrode are fluctuations in the resonance characteristics at the time of alcohol adhesion when the thickness is 0.5 mm, the solid line indicates the initial value and the chain line indicates one hour after the alcohol adhesion.
[0028]
As can be seen from FIG. 4, the liquid permeates due to the gap between the piezoelectric vibrator 10 and the diaphragm 14, and the characteristics fluctuate. If the resonance frequency shifts, the signal from the predetermined driving oscillation circuit does not match and sufficient atomization efficiency cannot be achieved.
[0029]
【The invention's effect】
The piezoelectric resonator for an atomizer of the present invention is formed by forming an excitation electrode on one main surface of an annular piezoelectric substrate and forming an excitation electrode having an electrodeless area on the other main surface. The piezoelectric characteristics of the vibrator can be improved to help the vibration of the diaphragm, and the atomization efficiency can be increased. Accordingly, it is possible to provide a piezoelectric resonator for an atomizing device that is not different from a case where full-surface electrodes are formed on both main surfaces.
[0030]
Further, since there is a sufficient electrodeless region on the other main surface of the piezoelectric substrate, it is possible to prevent the occurrence of defects in the polarization process in which a high voltage is applied even if the excitation electrode is formed. Accordingly, the piezoelectric resonator for an atomizer can be easily processed and can be manufactured with a high yield, so that the piezoelectric resonator can be mass-produced at a low cost. In terms of characteristics, high atomization efficiency can be obtained with low power.
[0031]
In addition, a structure is adopted in which a vibration region is attached by forming a solder area from the inner periphery side to the outer periphery side of the excitation electrode formed on the entire principal surface of the piezoelectric substrate, so that a gap is formed between the piezoelectric substrate and the vibration plate. Therefore, it is possible to provide a piezoelectric resonator for an atomizing device which has no vibration division and has good vibration characteristics in which the resonance point does not shift when a liquid to be atomized is attached.
[Brief description of the drawings]
1A is a front view of a piezoelectric resonator for an atomizer according to the present invention, and FIG. 1B is a sectional view taken along line AA of FIG.
2A and 2B are three views showing the piezoelectric vibrator of the present invention, in which FIG. 2A is a plan view thereof, FIG. 2B is a sectional view taken along line BB in FIG. 2A, and FIG.
3A is a diagram for explaining resonance characteristics when there is no gap between the piezoelectric substrate and the diaphragm, FIG. 3B is when the gap is 0.3 mm, and FIG. 3C is 0.5 mm. .
4A and 4B show the influence of resonance characteristics when a liquid adheres to the piezoelectric resonator for an atomizer according to the present invention. FIG. 4A shows a case where there is no gap, and FIG. 4B shows a case where a gap is formed.
FIGS. 5A and 5B are a conventional piezoelectric resonator for an atomizer, wherein FIG. 5A is a front view and FIG. 5B is a central longitudinal sectional view.
6A and 6B are trihedral views showing a conventional piezoelectric vibrator, in which FIG. 6A is a plan view, FIG. 6B is a central longitudinal sectional view, and FIG. 6C is a bottom view.
[Explanation of symbols]
11, 13: Excitation electrode 12: Piezoelectric substrate 14: Vibration plate 15: Solder 16, 17: No electrode area

Claims

An annular piezoelectric substrate center was penetrated in a thickness direction, a pair of excitation vibronic electrode formed on both main surfaces of the piezoelectric substrate, distribution so as to cover the transmural hole on one main surface of the piezoelectric substrate It is set, and, and a vibration plate provided with pores in the central portion, the said excitation electrodes one main surface and formed on one principal surface of the piezoelectric substrate of the diaphragm is connected via a solder In the piezoelectric resonator for the atomizer
The excitation electrodes formed on one main surface of the piezoelectric substrate, the first main surface and Rutotomoni are formed in the same dimension of the piezoelectric substrate, the excitation electrode formed on the other main surface of the piezoelectric substrate, the wherein in a region excluding the outer peripheral side region and the inner peripheral side region of the other main surface of the piezoelectric substrate is formed smaller than the dimensions of the other main surface of the piezoelectric substrate, said diaphragm central portion facing the through-hole And, while being molded into a dome shape having the pores at the top, the inner periphery of the excitation electrode on one main surface of the piezoelectric substrate and the outer periphery of the diaphragm are connected via the solder, For an atomizing apparatus, wherein a movement of raising and lowering a dome portion is caused by a movement in which the diameter of the piezoelectric substrate expands or contracts to discharge liquid supplied to the through hole of the piezoelectric substrate from the pores . Piezoelectric resonator.