JP3267721B2 - Piezoelectric buzzer - Google Patents
Piezoelectric buzzerInfo
- Publication number
- JP3267721B2 JP3267721B2 JP01383293A JP1383293A JP3267721B2 JP 3267721 B2 JP3267721 B2 JP 3267721B2 JP 01383293 A JP01383293 A JP 01383293A JP 1383293 A JP1383293 A JP 1383293A JP 3267721 B2 JP3267721 B2 JP 3267721B2
- Authority
- JP
- Japan
- Prior art keywords
- piezoelectric
- buzzer
- electrode
- piezoelectric element
- impedance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Description
【０００１】[0001]
【産業上の利用分野】本発明は、圧電ブザーに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric buzzer.
【０００２】[0002]
【従来の技術】従来の圧電ブザーの駆動回路の一例を図
６に示し、３端子型圧電素子の等価回路を図７に示す。2. Description of the Related Art FIG. 6 shows an example of a conventional driving circuit for a piezoelectric buzzer, and FIG. 7 shows an equivalent circuit of a three-terminal type piezoelectric element.
【０００３】同図に示す圧電ブザー１は、自励振タイプ
・ブザーであり、以下のように動作する。The piezoelectric buzzer 1 shown in FIG. 1 is a self-excited buzzer and operates as follows.
【０００４】同図中Ｖｃｃで示す直流電圧が入力接点２
とＧＮＤ間に印加されると、圧電素子３に電圧が印加さ
れ、圧電素子３が直ちに充電される。そして、べース電
流がバイアス抵抗Ｒ1 及びベース抵抗Ｒ2 を通してトラ
ンジスタＴｒに流れ、このトランジスタＴｒは、直ちに
オンする。A DC voltage indicated by Vcc in FIG.
When a voltage is applied between the voltage and the GND, a voltage is applied to the piezoelectric element 3 and the piezoelectric element 3 is immediately charged. The base over scan current flows through the transistor Tr through a bias resistor R 1 and the base resistor R 2, the transistor Tr is turned on immediately.
【０００５】これと同時に圧電素子３の主電極Ａ・共通
電極Ｂ間に放電電流が流れ始め、圧電素子３の帰還電極
Ｃには正の電圧が誘起され、その電圧がトランジスタＴ
ｒのベースに印加されるため、トランジスタＴｒは、継
続してオンし続ける。At the same time, a discharge current starts flowing between the main electrode A and the common electrode B of the piezoelectric element 3, and a positive voltage is induced at the feedback electrode C of the piezoelectric element 3, and the voltage is applied to the transistor T.
Since the voltage is applied to the base of r, the transistor Tr keeps on.
【０００６】そしてその放電電流が減少して圧電素子３
の帰還電極Ｃに誘起される電圧が、トランジスタＴｒの
ベース・エミッタ飽和電圧（ＶBE(sat) ）以下となり、
トランジスタＴｒをオフさせる。Then, the discharge current is reduced and the piezoelectric element 3
Is lower than the base-emitter saturation voltage (V BE (sat) ) of the transistor Tr,
The transistor Tr is turned off.
【０００７】すると今度は、圧電素子３の主電極Ａ・共
通電極Ｂ間に充電電流が流れ始め、帰還電極Ｃには負の
電圧が誘起され、トランジスタＴｒのベース電圧ＶBEを
さらに引き下げるため、しばらくの間トランジスタＴｒ
がオフし続ける。そして、圧電素子３の充電電流が減少
してトランジスタＴｒのベース電圧ＶBEがベース・エミ
ッタ（ＶBE(sat) ）以上となり、再びトランジスタＴｒ
をオフさせる。以後この素子３の充放電動作を繰り返し
行うことにより、連続鳴動発振することになる。Then, a charging current starts to flow between the main electrode A and the common electrode B of the piezoelectric element 3, and a negative voltage is induced on the feedback electrode C, so that the base voltage V BE of the transistor Tr is further reduced. Transistor Tr for a while
Keeps off. Then, the charging current of the piezoelectric element 3 decreases, and the base voltage V BE of the transistor Tr becomes equal to or higher than the base emitter (V BE (sat) ).
Off. Thereafter, by repeating the charging / discharging operation of the element 3, continuous ring oscillation is performed.
【０００８】ここで、圧電素子３の主電極Ａ・共通電極
Ｂ間と帰還電極Ｃ・共通電極Ｂ間の伝送特性（帰還電極
・共通電極間電圧Ｖ2 ）／（主電極・共通電極間電圧Ｖ
1 ）を図４及び図５に示す。Here, the transmission characteristic between the main electrode A and the common electrode B of the piezoelectric element 3 and between the feedback electrode C and the common electrode B (return electrode-common electrode voltage V 2 ) / (main electrode-common electrode voltage) V
1 ) is shown in FIG. 4 and FIG.
【０００９】図４から圧電素子３の帰還電極Ｃに誘起さ
れる電圧は、基本波の他に高調波成分を含んでいること
が分かる。通常は、同図に示すように、基本波が高調波
に比べて大きく、高調波により帰還電極Ｃに誘起される
電圧は無視できるので、基本波で鳴動する。図６に示す
駆動回路では、基本波と高調波のゲインが同程度なら図
５に示すように発振のための位相条件を基本波，高調波
と共に満たしているので基本波に高調波が乗った形で動
作する。このため、トランジスタＴｒの動作は複雑にな
るが、高調波成分は通常人間の耳には聞こえない範囲に
あるので、ブザーとしては、基本波で聞こえて正常に動
作することになる。FIG. 4 shows that the voltage induced on the feedback electrode C of the piezoelectric element 3 contains a harmonic component in addition to the fundamental wave. Normally, as shown in the figure, the fundamental wave is larger than the harmonic, and the voltage induced on the feedback electrode C by the harmonic is negligible. In the drive circuit shown in FIG. 6, if the gains of the fundamental wave and the harmonics are substantially the same, the fundamental wave and the harmonics satisfies the phase condition for oscillation as shown in FIG. Work in shape. For this reason, the operation of the transistor Tr becomes complicated, but since the harmonic component is usually in a range that cannot be heard by human ears, the buzzer can be normally heard by the fundamental wave.
【００１０】なお、図６に示す駆動回路では、一般に、
Ｒ1 に１００ｋΩ程度，Ｒ2 に数ｋΩ，Ｒ3 に数百Ωが
用いられる。In the drive circuit shown in FIG. 6, generally,
100kΩ about the R 1, R 2 to several kW, several hundred Ω to R 3 is used.
【００１１】[0011]
【発明が解決しようとする課題】圧電素子３自体は、通
常、図４に示すように基本波と高調波にゲインの差（例
えば、２０ｄＢ）があるので、増幅素子の増幅度を選択
することによって、圧電ブザー１は基本波で動作する。Since the piezoelectric element 3 itself usually has a gain difference (for example, 20 dB) between the fundamental wave and the harmonic as shown in FIG. 4, it is necessary to select the amplification degree of the amplifying element. Accordingly, the piezoelectric buzzer 1 operates with the fundamental wave.
【００１２】しかしながら、圧電素子３の帰還電極Ｃ・
共通電極Ｂ間にインピーダンスが接続されると、図４に
示すゲインは、減少する。通常の圧電ブザー１の駆動回
路は、図６に示すような構成となっているため、圧電素
子３の帰還電極Ｃ・共通電極Ｂ間に接続される等価イン
ピーダンスは、基本周波数において圧電素子３自体のイ
ンピーダンスに比べて低いので、圧電素子３の伝送特性
の基本波と高調波のゲインの差が小さくなってしまう。However, the feedback electrode C of the piezoelectric element 3
When the impedance is connected between the common electrodes B, the gain shown in FIG. 4 decreases. Since the driving circuit of the ordinary piezoelectric buzzer 1 has a configuration as shown in FIG. 6, the equivalent impedance connected between the feedback electrode C and the common electrode B of the piezoelectric element 3 is equal to the piezoelectric element 3 itself at the fundamental frequency. , The difference between the gain of the fundamental wave and the gain of the harmonic of the transmission characteristic of the piezoelectric element 3 becomes small.
【００１３】このため、圧電ブザー１に印加される音響
インピーダンス等が変化すると基本波のゲインが減少し
（高調波は、ほとんど変化しない）、この減少分が大き
くなりトランジスタＴｒで増幅しきれなくなると、圧電
ブザーは動作を停止するか、又は高調波発振を起こし
て、ブザーの音が聞こえなくなり、圧電ブザーとして機
能しなくなるという問題があった。For this reason, when the acoustic impedance or the like applied to the piezoelectric buzzer 1 changes, the gain of the fundamental wave decreases (harmonics hardly change), and when this decrease increases, the transistor Tr cannot amplify it. However, the piezoelectric buzzer stops operating or causes harmonic oscillation, so that the sound of the buzzer cannot be heard and the buzzer does not function as a piezoelectric buzzer.
【００１４】そこで、本発明は、上記事情に鑑みてなさ
れたものであり、高調波発振を防止してブザー動作の信
頼性向上を図った圧電ブザーを提供することを目的とす
る。The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a piezoelectric buzzer that prevents harmonic oscillation and improves the reliability of the buzzer operation.
【００１５】[0015]
【課題を解決するための手段】上記目的を達成するため
に請求項１記載の圧電ブザーは、主電極，共通電極及び
帰還電極を備えた３端子型の圧電素子と、増幅素子とを
有する圧電ブザーにおいて、前記増幅素子として高入力
インピーダンスの素子を用いて圧電ブザーを構成し、当
該圧電ブザーの鳴動周波数における前記圧電素子の帰還
電極・共通電極間に接続されるインピーダンスを、該電
極間のインピーダンスの１／２以上としたことを特徴と
するものである。According to a first aspect of the present invention, there is provided a piezoelectric buzzer comprising a three-terminal type piezoelectric element having a main electrode, a common electrode, and a feedback electrode, and an amplifying element. In the buzzer, a piezoelectric buzzer is configured by using an element having a high input impedance as the amplifying element.
Feedback of the piezoelectric element at the sound frequency of the piezoelectric buzzer
The impedance connected between the electrode and the common electrode is
It is characterized in that the impedance is at least 1/2 of the impedance between the poles .
【００１６】[0016]
【００１７】[0017]
【作用】上記構成の請求項１記載の圧電ブザーによれ
ば、増幅素子として高入力インピーダンスの素子を用い
ることにより、当該圧電ブザーの高調波発振を防止でき
るので、ブザー動作の信頼性向上を図れる。According to the piezoelectric buzzer according to the first aspect of the present invention, by using a high input impedance element as the amplifying element, harmonic oscillation of the piezoelectric buzzer can be prevented, so that the reliability of the buzzer operation can be improved. .
【００１８】また、圧電素子の帰還電極・共通電極間に
接続されるインピーダンスを、該電極間のインピーダン
スの１／２以上としたことにより、音響インピーダンス
等の変化により基本波のゲインが減少しても、基本波の
ゲインが高調波のゲインより小さくならないため、当該
圧電ブザーの高調波発振を防止できるので、ブザー動作
の信頼性向上を図れる。 Further, the impedance connected between the return electrode, the common electrode of the piezoelectric element, by which is 1/2 or more of the impedance between the electrodes, the gain of the fundamental wave by a change in such acoustic impedance is reduced In addition, since the gain of the fundamental wave does not become smaller than the gain of the harmonic wave, harmonic oscillation of the piezoelectric buzzer can be prevented, so that the reliability of the buzzer operation can be improved.
【００１９】[0019]
【実施例】以下、本発明の実施例を図面を参照して詳述
する。Embodiments of the present invention will be described below in detail with reference to the drawings.
【００２０】図１は本発明の圧電ブザーの第１の実施例
を示す駆動回路である。FIG. 1 is a drive circuit showing a first embodiment of the piezoelectric buzzer of the present invention.
【００２１】同図に示す第１の実施例の圧電ブザー１０
は、主電極Ａ，共通電極Ｂ及び帰還電極Ｃを備えた３端
子型の圧電素子３と、複数の抵抗Ｒ1 ，Ｒ2 ，Ｒ3 と、
増幅素子としてのエンハンスメント形ＦＥＴ（電界効果
トランジスタ）１２とを有して構成されている。The piezoelectric buzzer 10 according to the first embodiment shown in FIG.
Is a three-terminal type piezoelectric element 3 having a main electrode A, a common electrode B and a feedback electrode C, a plurality of resistors R 1 , R 2 , R 3 ,
It has an enhancement type FET (field effect transistor) 12 as an amplifying element.
【００２２】前記ＦＥＴ１２は、高入力インピーダンス
の素子であり、そのドレン・ゲート間に抵抗Ｒ1 を接続
し、ソース・ゲート間に抵抗Ｒ2 を接続している。The FET 12 is a device having a high input impedance. A resistor R 1 is connected between the drain and the gate, and a resistor R 2 is connected between the source and the gate.
【００２３】このＦＥＴ１２に接続された抵抗Ｒ1 ，Ｒ
2 は、ＦＥＴ１２の入力インピーダンスすなわち圧電素
子３の帰還電極Ｃ・共通電極Ｂ間の等価インピーダンス
が該電極Ｃ，Ｂ間のインピーダンスの１／２以上となる
ようにその抵抗値を選定する必要がある。なお、ＦＥＴ
１２の入力インピーダンスは、Ｒ1 ＊Ｒ2 ／（Ｒ1 ＋Ｒ
2 ）で表される。The resistors R 1 and R connected to the FET 12
2 is that the resistance value must be selected so that the input impedance of the FET 12, that is, the equivalent impedance between the feedback electrode C and the common electrode B of the piezoelectric element 3 is equal to or more than 1/2 of the impedance between the electrodes C and B. . In addition, FET
12 has an input impedance of R 1 * R 2 / (R 1 + R
2 ).
【００２４】圧電ブザー１０の大きさ，構造等により異
なるが、通常、圧電素子３に回路を接続しない状態で
は、基本波と高調波のゲインの差は、２０ｄＢ以上あ
る。圧電素子３の帰還電極Ｃ・共通電極Ｂ間に該電極
Ｃ，Ｂ間のインピーダンスの１／２の値の抵抗を接続す
ると、圧電素子３に何も接続しない場合より、基本波の
ゲインが約１０ｄＢ低くなり、高調波とのゲイン差が約
１０ｄＢ狭くなる。一方、音響インピーダンス等の変化
による基本波のゲインの減少は、数ｄＢ程度である。従
って、ＦＥＴ１２の入力インピーダンスを、圧電素子３
の帰還電極Ｃ・共通電極Ｂ間のインピーダンスの１／２
以上とすることにより、基本波のゲインが高調波のゲイ
ンより小さくならないため、高調波発振を防止できる。Although it differs depending on the size and structure of the piezoelectric buzzer 10, the difference between the gain of the fundamental wave and the gain of the higher harmonic wave is usually 20 dB or more when no circuit is connected to the piezoelectric element 3. When a resistor having a value of 1/2 of the impedance between the electrodes C and B is connected between the feedback electrode C and the common electrode B of the piezoelectric element 3, the gain of the fundamental wave is reduced as compared with the case where nothing is connected to the piezoelectric element 3. 10 dB lower, and the gain difference from the harmonic becomes narrower by about 10 dB. On the other hand, the decrease in the gain of the fundamental wave due to a change in acoustic impedance or the like is about several dB. Therefore, the input impedance of the FET 12 is
Of the impedance between the feedback electrode C and the common electrode B
With the above, the gain of the fundamental wave does not become smaller than the gain of the harmonic, so that harmonic oscillation can be prevented.
【００２５】図２は本発明の圧電ブザーの第２の実施例
を示す駆動回路である。FIG. 2 is a drive circuit showing a second embodiment of the piezoelectric buzzer according to the present invention.
【００２６】同図に示す第２の実施例の圧電ブザー２０
は、図１に示す抵抗Ｒ1 ，Ｒ2 の接続を変更したもので
ある。通常、抵抗Ｒ2 に大きな抵抗値を有するものが用
いられるので、これにより第１の実施例と同様に圧電素
子３の帰還電極Ｃ・共通電極Ｂ間の等価インピーダンス
を大きくできる。The piezoelectric buzzer 20 of the second embodiment shown in FIG.
Is a modification of the connection between the resistors R 1 and R 2 shown in FIG. Usually, is used which has a large resistance value to the resistor R 2, thereby increasing the equivalent impedance between the return electrode C · common electrode B of the piezoelectric element 3 as in the first embodiment.
【００２７】図３は本発明の圧電ブザーの第３の実施例
を示す駆動回路である。FIG. 3 is a drive circuit showing a third embodiment of the piezoelectric buzzer according to the present invention.
【００２８】同図に示す第３の実施例の圧電ブザー３０
は、増幅素子としてトランジスタＴｒを用い、このトラ
ンジスタＴｒのコレクタ・ベース間にバイアス抵抗Ｒ１
とベース抵抗Ｒ２を直列接続し、コレクタ・エミッタ間
に圧電素子３の主電極Ａを接続し、バイアス抵抗Ｒ１と
ベース抵抗Ｒ２との接続点に圧電素子３の帰還電極Ｃを
接続したものである。当該圧電ブザー３０の鳴動周波数
におけるベース抵抗Ｒ２のインピーダンスを、第１の実
施例と同様に圧電素子３の帰還電極Ｃ・共通電極Ｂ間の
インピーダンスの１／２以上となるようにしている。The piezoelectric buzzer 30 of the third embodiment shown in FIG.
Uses a transistor T r as an amplifying element, the bias resistor R 1 between the collector and base of the transistor T r
The base resistance R 2 connected in series with, and connect the main electrode A of the piezoelectric element 3 between the collector and the emitter, and connecting the return electrode C of the piezoelectric element 3 to a connection point between the bias resistor R 1 and the base resistor R 2 Things. The impedance of the base resistance R 2 in ringing frequency of the piezoelectric buzzer 30 is set to be 1/2 or more of the impedance between the return electrode C · common electrode B of the piezoelectric element 3 as in the first embodiment.
【００２９】なお、本発明は上記実施例に限定されず、
その要旨を変更しない範囲内で種々に変形実施可能であ
る。The present invention is not limited to the above embodiment,
Various modifications can be made without departing from the scope of the invention.
【００３０】[0030]
【発明の効果】上述したように請求項１記載の発明によ
れば、増幅素子として高入力インピーダンスの素子を用
いているので、高調波発振を防止してブザー動作の信頼
性向上を図った圧電ブザーを提供することができる。As described above, according to the first aspect of the present invention, since an element having a high input impedance is used as the amplifying element, the piezoelectric oscillation which prevents the harmonic oscillation and improves the reliability of the buzzer operation is achieved. A buzzer can be provided.
【００３１】また、圧電素子の帰還電極・共通電極間に
接続されるインピーダンスを、該電極間のインピーダン
スの１／２以上としているので、高調波発振を防止して
ブザー動作の信頼性向上を図った圧電ブザーを提供する
ことができる。 Further, the impedance connected between the return electrode, the common electrode of the piezoelectric element, since 1/2 or more of the impedance between the electrodes, efforts to improve the reliability of the buzzer operation to prevent harmonic oscillation A piezoelectric buzzer can be provided.
【図１】本発明の圧電ブザーの第１の実施例を示す駆動
回路である。FIG. 1 is a driving circuit showing a first embodiment of a piezoelectric buzzer according to the present invention.
【図２】本発明の圧電ブザーの第２の実施例を示す駆動
回路である。FIG. 2 is a drive circuit showing a second embodiment of the piezoelectric buzzer of the present invention.
【図３】本発明の圧電ブザーの第３の実施例を示す駆動
回路である。FIG. 3 is a drive circuit showing a third embodiment of the piezoelectric buzzer of the present invention.
【図４】圧電素子の伝送特性（ゲイン）を示すグラフで
ある。FIG. 4 is a graph showing transmission characteristics (gain) of a piezoelectric element.
【図５】圧電素子の伝送特性（位相）を示すグラフであ
る。FIG. 5 is a graph showing transmission characteristics (phase) of a piezoelectric element.
【図６】従来の圧電ブザーの一例を示す駆動回路であ
る。FIG. 6 is a drive circuit showing an example of a conventional piezoelectric buzzer.
【図７】３端子型圧電素子の等価回路である。FIG. 7 is an equivalent circuit of a three-terminal piezoelectric element.
３ 圧電素子 １０，２０，３０ 圧電ブザー １２ ＦＥＴ（増幅素子） Ａ 圧電素子の主電極 Ｂ 圧電素子の共通電極 Ｃ 圧電素子の帰還電極 Ｒ1 ，Ｒ2 ，Ｒ3 抵抗 Ｔｒ トランジスタ（増幅素子）3 return electrode R 1 of the common electrode C piezoelectric element of the main electrode B piezoelectric element of the piezoelectric elements 10, 20 and 30 piezoelectric buzzer 12 FET (amplifying element) A piezoelectric element, R 2, R 3 resistors Tr transistor (amplifying element)
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) G10K 9/12 ──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 7 , DB name) G10K 9/12
Claims (1)
３端子型の圧電素子と、増幅素子とを有する圧電ブザー
において、前記増幅素子として高入力インピーダンスの
素子を用いて圧電ブザーを構成し、当該圧電ブザーの鳴
動周波数における前記圧電素子の帰還電極・共通電極間
に接続されるインピーダンスを、該電極間のインピーダ
ンスの１／２以上としたことを特徴とする圧電ブザー。1. A piezoelectric buzzer having a three-terminal type piezoelectric element having a main electrode, a common electrode, and a feedback electrode, and an amplifying element, wherein the piezoelectric buzzer is configured using a high input impedance element as the amplifying element. , The piezoelectric buzzer sounds
Between the feedback electrode and the common electrode of the piezoelectric element at the operating frequency
The impedance connected to the
A piezoelectric buzzer characterized in that it has a half or more of the impedance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP01383293A JP3267721B2 (en) | 1993-01-29 | 1993-01-29 | Piezoelectric buzzer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP01383293A JP3267721B2 (en) | 1993-01-29 | 1993-01-29 | Piezoelectric buzzer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06230785A JPH06230785A (en) | 1994-08-19 |
| JP3267721B2 true JP3267721B2 (en) | 2002-03-25 |
Family
ID=11844250
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP01383293A Expired - Lifetime JP3267721B2 (en) | 1993-01-29 | 1993-01-29 | Piezoelectric buzzer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3267721B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103456289A (en) * | 2013-08-05 | 2013-12-18 | 创正防爆电器有限公司 | Safety type piezoelectric buzzer |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SI1851349T1 (en) | 2005-01-27 | 2010-08-31 | Peruke Proprietary Ltd | A method of producing titanium |
-
1993
- 1993-01-29 JP JP01383293A patent/JP3267721B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103456289A (en) * | 2013-08-05 | 2013-12-18 | 创正防爆电器有限公司 | Safety type piezoelectric buzzer |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06230785A (en) | 1994-08-19 |
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