JP5303759B2 - Drive unit for piezoelectric vibrator - Google Patents
Drive unit for piezoelectric vibrator Download PDFInfo
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- JP5303759B2 JP5303759B2 JP2009042092A JP2009042092A JP5303759B2 JP 5303759 B2 JP5303759 B2 JP 5303759B2 JP 2009042092 A JP2009042092 A JP 2009042092A JP 2009042092 A JP2009042092 A JP 2009042092A JP 5303759 B2 JP5303759 B2 JP 5303759B2
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- piezoelectric vibrator
- iron core
- converter
- current flowing
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Description
本発明は、圧電振動子を用いて、超音波振動を安定して発生する技術を提供するものである。 The present invention provides a technique for stably generating ultrasonic vibration using a piezoelectric vibrator.
一般的なランジュバン型超音波圧電振動子には共振周波数frがあり、共振周波数に合致した駆動信号を与えると、最も効率よく振動する共振という性質がある。ただし共振の範囲は狭くかつ温度等で推移するため、常に共振周波数を正確に追いかける必要がある。
一方、圧電振動子は図2の等価回路のとおり、質量にあたるインダクタンスLとバネ定数に当るコンデンサCと負荷に当る抵抗Rが直列につながっている。このLCR直列回路が機械系の振動にあたる。他方、電気的に寄生する容量Cdも存在する。共振が起きている時は、LのインピーダンスとCのインピーダンスが相殺され、LCR直列回路に流れる電流の位相と印加電圧の位相が一致する。
そこで、圧電振動子に流れる電流と印加電圧の位相が一致するようにPLL回路を組むことで共振に近い状態を保つことができる。共振点との誤差は、寄生コンデンサCdに流れる電流が原因である。
この誤差をなくすために、特許文献1のとおり圧電振動子と並列に補正用コンデンサを挿入し、その電流値を引き算することで寄生コンデンサCdに流れる電流を相殺する回路がある。これは共振周波数が変わっても誤差が生じない長所がある。ただし、比較回路、乗算回路、減算回路が必要となり、回路が複雑となる欠点があった。また周波数が高くなればなるほど、各回路の動作速度が問題となり限界があった。
On the other hand, in the piezoelectric vibrator, as shown in the equivalent circuit of FIG. 2, an inductance L corresponding to mass, a capacitor C corresponding to a spring constant, and a resistance R corresponding to a load are connected in series. This LCR series circuit is the vibration of the mechanical system. On the other hand, there is an electrically parasitic capacitance Cd. When resonance occurs, the impedance of L and the impedance of C cancel each other, and the phase of the current flowing through the LCR series circuit matches the phase of the applied voltage.
Therefore, a state close to resonance can be maintained by assembling a PLL circuit so that the phase of the applied current and the current flowing through the piezoelectric vibrator coincide. The error from the resonance point is caused by the current flowing through the parasitic capacitor Cd.
In order to eliminate this error, there is a circuit that cancels out the current flowing through the parasitic capacitor Cd by inserting a correction capacitor in parallel with the piezoelectric vibrator and subtracting the current value as disclosed in Patent Document 1. This has the advantage that no error occurs even if the resonance frequency changes. However, a comparison circuit, a multiplication circuit, and a subtraction circuit are required, and there is a disadvantage that the circuit becomes complicated. Also, the higher the frequency, the more problematic the operation speed of each circuit, and there was a limit.
圧電振動子から流れる電流から、圧電振動子と並列に接続された補正用コンデンサから流れる電流を減算する機能を、単純な構造で実現し、かつより高い周波数で動作可能とすることが課題である。 The problem is to realize the function of subtracting the current flowing from the correction capacitor connected in parallel with the piezoelectric vibrator from the current flowing from the piezoelectric vibrator with a simple structure and to operate at a higher frequency. .
本発明は、圧電振動子から流れる電流から、圧電振動子と並列に接続された補正用コンデンサから流れる電流を減算する機能を、高透磁率の磁性材料で作られる鉄心の芯線を中心に、互いに左右反対に回転させることで、鉄心の磁路には両者の電流を減算した値の磁力が生じ、この磁力を変換器で電気信号として取り出すことにより、両電流の減算結果が取り出せる。 The present invention has the function of subtracting the current flowing from the correcting capacitor connected in parallel with the piezoelectric vibrator from the current flowing from the piezoelectric vibrator, with the core wire made of a magnetic material having a high magnetic permeability as the center. By rotating in the opposite direction, a magnetic force of a value obtained by subtracting both currents is generated in the magnetic path of the iron core, and by subtracting this magnetic force as an electrical signal by the converter, the subtraction result of both currents can be extracted.
本発明の請求項1の方法により、単純な構造で確実に寄生コンデンサCdの影響をなくすことが出来る。これにより、常に共振周波数を正確に追従でき、効率の高い振動を発生することができる。また、鉄心は単純なため、回路が簡単になるとともに、高い周波数での動作が可能となる。 According to the method of claim 1 of the present invention, the influence of the parasitic capacitor Cd can be reliably eliminated with a simple structure. As a result, the resonance frequency can always be accurately followed and high-efficiency vibration can be generated. In addition, since the iron core is simple, the circuit becomes simple and operation at a high frequency is possible.
以下、本発明の実施形態を説明する。なお、以下に説明する実施形態は、本発明を実施するにあたっての具体例であるから、技術的に種々の限定がなされているが、本発明は、以下の説明において特に本発明を限定する旨明記されていない限り、これらの形態に限定されるものではない。 Embodiments of the present invention will be described below. The embodiments described below are specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.
図1に本発明の実施例を示す。圧電振動子10と、これに高周波駆動電圧を与える発振源50を設け、圧電振動子10と並列に補正用コンデンサ20を接続し、高周波駆動電圧を印加する。圧電振動子10に流れる電流と補正用コンデンサ20に流れる電流を、高透磁率の磁性材料で作られる鉄心30の芯線を中心に互いに左右反対に回転させることで、鉄心30の磁路には両者の電流を減算した値の磁力が生じる。この磁力を変換器40で電気信号として取り出し、正しく補正された電流位相を検出する。PLL回路等で電流位相と電圧位相を比べ、同位相となるように印加電圧の周波数を制御することで、正確な共振周波数追従が可能となる。 FIG. 1 shows an embodiment of the present invention. A piezoelectric vibrator 10 and an oscillation source 50 for applying a high frequency driving voltage thereto are provided, and a correcting capacitor 20 is connected in parallel with the piezoelectric vibrator 10 to apply a high frequency driving voltage. By rotating the current flowing through the piezoelectric vibrator 10 and the current flowing through the correction capacitor 20 opposite to each other about the core wire of the core 30 made of a high permeability magnetic material, The magnetic force of the value obtained by subtracting the current of is generated. This magnetic force is taken out as an electrical signal by the converter 40, and the correctly corrected current phase is detected. By comparing the current phase and the voltage phase with a PLL circuit or the like and controlling the frequency of the applied voltage so as to be the same phase, it is possible to accurately follow the resonance frequency.
圧電振動子10の寄生コンデンサ容量Cdと補正用コンデンサ20の容量Ddが同じなら、鉄心30への巻き数比は1:1でよい。Cd:Dd=N:1ならば、巻数を1:Nにすれば同じ効果が得られる。
鉄心30は透磁率の高い材質(フェライト等)を用い、形状は棒状またはリング状とする。
変換器40は、請求項3のとおり、鉄心30にコイルを巻き、両端に抵抗を接続することで実現できる。抵抗両端電圧には、圧電振動子の電流から寄生コンデンサの電流を差し引いた電流位相が得られる。
別の方式として、請求項4のとおり、鉄心30の磁路の中にホール素子を埋め込み、ホール素子の抵抗値から電流位相を計測する方式もある。
If the parasitic capacitor capacitance Cd of the piezoelectric vibrator 10 and the capacitance Dd of the correction capacitor 20 are the same, the turns ratio to the iron core 30 may be 1: 1. If Cd: Dd = N: 1, the same effect can be obtained by setting the number of turns to 1: N.
The iron core 30 is made of a material having high magnetic permeability (such as ferrite) and has a rod shape or a ring shape.
As described in claim 3, the converter 40 can be realized by winding a coil around the iron core 30 and connecting resistors to both ends. A current phase obtained by subtracting the current of the parasitic capacitor from the current of the piezoelectric vibrator is obtained as the voltage across the resistor.
As another method, as described in claim 4, there is a method of embedding a Hall element in the magnetic path of the iron core 30 and measuring the current phase from the resistance value of the Hall element.
超音波の利用は洗浄や計測や加工や医療にまで広がっている。効率の高い振動発生が実現することにより、製品の出力向上やコスト削減や省エネ化などが期待できる。 The use of ultrasonic waves has spread to cleaning, measurement, processing, and medical care. Realization of highly efficient vibration generation can be expected to improve product output, reduce costs and save energy.
10 圧電振動子
20 補正用コンデンサ
30 鉄心
40 鉄心の磁路の磁力を電気信号に変える変換器
50 高周波駆動電圧を与える発振源
DESCRIPTION OF SYMBOLS 10 Piezoelectric vibrator 20 Correction capacitor 30 Iron core 40 Converter 50 that changes the magnetic force of the magnetic path of the iron core into an electrical signal
Claims (4)
前記圧電振動子10を共振点で駆動すべく前記発振源50を制御する制御回路とを具備したことを特長とする圧電振動子の駆動装置。 Piezoelectric vibrator 10, oscillation source 50 for applying a high frequency drive voltage to the piezoelectric vibrator 10, correction capacitor 20 connected in parallel with the piezoelectric vibrator 10, current flowing through the piezoelectric vibrator 10 and the correction An iron core 30 in which the current flowing through the capacitor 20 is rotated opposite to each other about the core wire, and a converter 40 that phase-combines the magnetic force flowing in the magnetic path of the iron core 30 into a current signal,
A drive device for a piezoelectric vibrator, comprising: a control circuit for controlling the oscillation source 50 to drive the piezoelectric vibrator 10 at a resonance point.
The drive device according to claim 2, wherein the converter (40) includes a Hall element disposed in a magnetic path of the iron core (30) and a circuit that measures a magnetic field passing through the Hall element.
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JP2009042092A JP5303759B2 (en) | 2009-02-25 | 2009-02-25 | Drive unit for piezoelectric vibrator |
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JP2009042092A JP5303759B2 (en) | 2009-02-25 | 2009-02-25 | Drive unit for piezoelectric vibrator |
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JP2010194456A JP2010194456A (en) | 2010-09-09 |
JP5303759B2 true JP5303759B2 (en) | 2013-10-02 |
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JP2009042092A Expired - Fee Related JP5303759B2 (en) | 2009-02-25 | 2009-02-25 | Drive unit for piezoelectric vibrator |
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Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
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US5152762A (en) * | 1990-11-16 | 1992-10-06 | Birtcher Medical Systems, Inc. | Current leakage control for electrosurgical generator |
JP3486469B2 (en) * | 1994-10-26 | 2004-01-13 | オリンパス株式会社 | Drive device for piezoelectric vibrator |
JP3959077B2 (en) * | 2004-06-30 | 2007-08-15 | Tdk株式会社 | Parallel drive power supply |
JP4321412B2 (en) * | 2004-09-02 | 2009-08-26 | 株式会社デンソー | Current measuring device |
JP2007248107A (en) * | 2006-03-14 | 2007-09-27 | Harada Sangyo Kk | Power supply noise detector |
JP2007299838A (en) * | 2006-04-28 | 2007-11-15 | Hitachi Metals Ltd | Magnetic core for current transformer, current transformer using same, and electric power meter |
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