JP3168120B2 - Speaker drive circuit - Google Patents
Speaker drive circuitInfo
- Publication number
- JP3168120B2 JP3168120B2 JP17731494A JP17731494A JP3168120B2 JP 3168120 B2 JP3168120 B2 JP 3168120B2 JP 17731494 A JP17731494 A JP 17731494A JP 17731494 A JP17731494 A JP 17731494A JP 3168120 B2 JP3168120 B2 JP 3168120B2
- Authority
- JP
- Japan
- Prior art keywords
- resistance
- resistor
- output
- speaker
- input
- 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
Landscapes
- Piezo-Electric Transducers For Audible Bands (AREA)
- Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
- Circuit For Audible Band Transducer (AREA)
Description
【産業上の利用分野】本発明はスピーカ駆動回路に関
し、特にセラミックスピーカの低音域における電気／音
響変換効率の低下が防止でき、十分な供給電力が得られ
るスピーカ駆動回路に係わる。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loudspeaker driving circuit, and more particularly to a loudspeaker driving circuit capable of preventing a decrease in electric / sound conversion efficiency in a low-frequency range of a ceramic loudspeaker and obtaining sufficient power supply.
【従来の技術】従来から、セラミックスピーカ等に使用
されるスピーカ駆動回路は図６に示すように、オペアン
プ３１、スピーカ３２、抵抗Ｒ11、抵抗Ｒ12、コンデン
サＣ11、Ｃ12等の周辺部品で構成されている。オペアン
プ３１の（−）入力側には抵抗Ｒ11を介してコンデンサ
Ｃ11が接続され、オペアンプ３１の（−）入力側と出力
側の間には抵抗Ｒ12が接続されている。また、オペアン
プ３１の（＋）入力側には一端が基準電位点に接続され
たコンデンサＣ12の他端が接続されている。オペアンプ
３１の出力側は一端が基準電位点に接続されたセラミッ
クスピーカ３２の他端が接続されている。ドアホン装置
等の室内親機から送出される音声信号ｆ11はオペアンプ
３１に接続されているコンデンサＣ11、抵抗Ｒ11及びオ
ペアンプ３１を介して玄関子機に設けられたセラミック
スピーカ３２へ送出される。セラミックスピーカ３２は
電気的にコンデンサと等価であるから動作特性は図７に
示すように横軸を音声信号ｆ11の範囲での周波数ｆ（Ｈ
ｚ）、縦軸をセラミックスピーカ３２のインピーダンス
ＺS（Ω）とすれば、に示す特性曲線となる。この特
性曲線は数式（１）により求められる。2. Description of the Related Art Conventionally, a speaker driving circuit used for a ceramic speaker or the like is constituted by peripheral parts such as an operational amplifier 31, a speaker 32, a resistor R11, a resistor R12, and capacitors C11 and C12 as shown in FIG. I have. A capacitor C11 is connected to the (−) input side of the operational amplifier 31 via a resistor R11, and a resistor R12 is connected between the (−) input side and the output side of the operational amplifier 31. The other end of the capacitor C12 whose one end is connected to the reference potential point is connected to the (+) input side of the operational amplifier 31. The output side of the operational amplifier 31 is connected to the other end of the ceramic speaker 32 whose one end is connected to the reference potential point. The audio signal f11 transmitted from the indoor master unit such as a door phone device is transmitted to the ceramic speaker 32 provided in the entrance unit via the capacitor C11, the resistor R11 and the operational amplifier 31 connected to the operational amplifier 31. Since the ceramic speaker 32 is electrically equivalent to a capacitor, the operating characteristics of the ceramic speaker 32 are represented by the frequency f (H) in the range of the audio signal f11 as shown in FIG.
z), and the vertical axis is the impedance ZS (Ω) of the ceramic speaker 32, the characteristic curve shown below is obtained. This characteristic curve is obtained by equation (1).
【数１】 但し１／ωＣはセラミックスピーカ３２の容量リアクタ
ンスである。また、セラミックスピーカ３２にオペアン
プ３１から供給される電力は、図８に示すように横軸を
音声信号ｆ11の範囲での周波数ｆ（Ｈｚ）、縦軸をスピ
ーカ３２への電力ＰB（Ｗ）とすれば、に示す特性曲
線となるこの特性曲線は数式（２）により求められる。(Equation 1) Here, 1 / ωC is the capacitance reactance of the ceramic speaker 32. As shown in FIG. 8, the power supplied from the operational amplifier 31 to the ceramic speaker 32 is a frequency f (Hz) in the range of the audio signal f11 on the horizontal axis, and a power PB (W) to the speaker 32 on the vertical axis. Then, this characteristic curve, which becomes the characteristic curve shown below, can be obtained by Expression (2).
【数２】 但し、ＶBはオペアンプ３１の出力電圧で一定、オペア
ンプ３１の出力インピーダンスは０、ＺSはセラミック
スピーカ３２のインピーダンスである。つまり、セラミ
ックスピーカ３２は図７に示すように周波数が低くなる
と、インピーダンスＺSが高くなるため、図８に示す
の特性曲線の低音域において供給電力が小さくなる。(Equation 2) Here, VB is constant at the output voltage of the operational amplifier 31, the output impedance of the operational amplifier 31 is 0, and ZS is the impedance of the ceramic speaker 32. That is, when the frequency of the ceramic speaker 32 decreases as shown in FIG. 7, the impedance ZS increases, so that the supplied power decreases in the low sound range of the characteristic curve shown in FIG.
【発明が解決しようとする課題】このようなオペアンプ
３１を使用した回路でセラミックスピーカ３２を駆動す
ると、低音域での電気／音響変換効率は極端に悪くな
り、筐体等の音響的対策を工夫しても低音域において供
給電力が小さくなるという難点がある。また、低域音量
の不足を音響的対策でカバーする試みがなされているが
低域音量が不十分であるという難点がある。When the ceramic speaker 32 is driven by a circuit using such an operational amplifier 31, the electric / acoustic conversion efficiency in a low-frequency range becomes extremely poor, and a sound measure such as a housing is devised. However, there is a drawback that the supplied power is reduced in a low frequency range. Attempts have been made to cover the lack of low-frequency sound with acoustic measures, but there is a disadvantage that the low-frequency sound is insufficient.
【発明の目的】本発明は、このような難点を解消するた
めになされたもので、セラミックスピーカの低音域にお
ける電気／音響変換効率の低下が防止でき、十分な供給
電力が得られるよう定電流源を使ってセラミックスピー
カを駆動することを目的とする。SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and it is intended to prevent a decrease in the electric / acoustic conversion efficiency of a ceramic speaker in a low sound range and to obtain a constant current so that a sufficient power supply can be obtained. The purpose is to drive a ceramic speaker using a source.
【課題を解決するための手段】この目的を達成するた
め、本発明のスピーカ駆動回路は、音声信号が入力され
音声信号により出力電流を変化させる定電流源と、定電
流源により駆動される容量性スピーカとを備え、容量性
スピーカは、セラミックスピーカで構成され、定電流源
は、オペアンプの一方の入力側に音声信号が入力される
入力抵抗を接続し、他方の入力側に基準電位点抵抗を介
して基準電位点に接続し、出力側から負帰還抵抗を介
し、また出力抵抗を経由し正帰還抵抗を介してそれぞれ
入力側に帰還接続し、正帰還抵抗と出力抵抗の接続点を
容量性スピーカに接続し、出力抵抗および正帰還抵抗の
和と基準電位点抵抗との比を、負帰還抵抗と入力抵抗と
の比に一致させたものである。また、定電流源は、オペ
アンプの一方の入力側に音声信号が入力される入力抵抗
を接続し、他方の入力側に基準電位点抵抗を介して基準
電位点に接続し、出力側から負帰還抵抗を介し、また出
力抵抗を経由し正帰還抵抗を介してそれぞれ入力側に帰
還接続し、出力抵抗を容量性スピーカに接続し、正帰還
抵抗と出力抵抗の間にバッファ機能を有するオペアンプ
を介在し、出力抵抗および正帰還抵抗の和と基準電位点
抵抗との比を、負帰還抵抗と入力抵抗との比に一致させ
たものである。In order to achieve this object, a speaker driving circuit according to the present invention comprises a constant current source which receives an audio signal and changes an output current according to the audio signal, and a capacitor driven by the constant current source. The capacitive speaker is composed of a ceramic speaker, and the constant current source is connected to an input resistor for inputting an audio signal to one input side of the operational amplifier, and a reference potential point resistor is connected to the other input side. To the reference potential point, and from the output side to the input side via the negative feedback resistor, and via the output resistance to the input side via the positive feedback resistor, and connect the connection point between the positive feedback resistor and the output resistor. In this case, the ratio of the sum of the output resistance and the positive feedback resistance to the reference potential point resistance matches the ratio of the negative feedback resistance to the input resistance. In the constant current source, an input resistor for inputting an audio signal is connected to one input side of the operational amplifier, the other input side is connected to a reference potential point via a reference potential point resistor, and a negative feedback is provided from the output side. A feedback connection is made to the input side via a resistor and a positive feedback resistor via an output resistor.The output resistor is connected to a capacitive speaker, and an operational amplifier with a buffer function is interposed between the positive feedback resistor and the output resistor. The ratio of the sum of the output resistance and the positive feedback resistance to the reference potential point resistance is made equal to the ratio of the negative feedback resistance to the input resistance.
【作用】このスピーカ駆動回路において、定電流源で容
量性スピーカを駆動すると、音声信号の低音域での電気
／音響変換効率が高くなる。定電流源でセラミックスピ
ーカを駆動すると、音声信号の低音域での電気／音響変
換効率が高くなる。また、オペアンプの一方の入力側に
入力抵抗を介して音声信号が入力されると、出力側から
負帰還抵抗を経由して電流が帰還する。同様に、オペア
ンプの他方の入力側に基準電位点抵抗を介して基準電位
点に接続すると、出力抵抗及び正帰還抵抗を経由して電
流が帰還する。出力抵抗および正帰還抵抗の和と基準電
位点抵抗との比を、負帰還抵抗と入力抵抗との比に一致
させると、正帰還抵抗と出力抵抗の接続点の容量性スピ
ーカは音声信号の低音域での電気／音響変換効率が高く
なる。更に、オペアンプの一方の入力側に入力抵抗を介
して音声信号が入力されると、出力側から負帰還抵抗を
経由して電流が帰還する。同様に、オペアンプの他方の
入力側に基準電位点抵抗を介して基準電位点に接続する
と、出力抵抗及び正帰還抵抗を経由して電流が帰還す
る。出力抵抗および正帰還抵抗の和と基準電位点抵抗と
の比を、負帰還抵抗と入力抵抗との比に一致させると、
正帰還抵抗と出力抵抗の間に介在したバッファ機能を有
するオペアンプを介して帰還する電流が増加し、容量性
スピーカは音声信号の低音域での電気／音響変換効率が
高くなり、駆動電流が増加する。In this speaker drive circuit, when a capacitive speaker is driven by a constant current source, the efficiency of electric / acoustic conversion in a low-frequency range of an audio signal increases. When the ceramic speaker is driven by the constant current source, the electric / acoustic conversion efficiency in the low sound range of the audio signal increases. When an audio signal is input to one input side of the operational amplifier via an input resistor, current is fed back from the output side via a negative feedback resistor. Similarly, when the other input side of the operational amplifier is connected to a reference potential point via a reference potential point resistor, current is fed back via an output resistor and a positive feedback resistor. If the ratio of the sum of the output resistance and the positive feedback resistance to the reference potential point resistance matches the ratio of the negative feedback resistance to the input resistance, the capacitive speaker at the connection point between the positive feedback resistance and the output resistance will have a low sound signal. The electric / sound conversion efficiency in the sound range is increased. Further, when a voice signal is input to one input side of the operational amplifier via an input resistor, current is fed back from the output side via a negative feedback resistor. Similarly, when the other input side of the operational amplifier is connected to a reference potential point via a reference potential point resistor, current is fed back via an output resistor and a positive feedback resistor. When the ratio of the sum of the output resistance and the positive feedback resistance to the reference potential point resistance matches the ratio of the negative feedback resistance to the input resistance,
The current that is fed back via the operational amplifier with a buffer function interposed between the positive feedback resistor and the output resistor increases, and the capacitive loudspeaker has a higher electric / acoustic conversion efficiency in the low-frequency range of the audio signal, and the driving current increases. I do.
【実施例】以下、本発明のスピーカ駆動回路をその好ま
しい実施例について図にしたがって詳述する。図１に示
すように、本発明のスピーカ駆動回路は、音声信号ｆ1
が入力され音声信号により出力電流を変化させる定電流
源１と、定電流源により駆動される容量性スピーカ２と
を備えている。また容量性スピーカは図２に示すように
セラミックスピーカ２ａで構成する。定電流源１ａは図
２に示すようにオペアンプ４の一方の入力側に音声信号
ｆ1が入力される入力抵抗Ｒ1を接続し、他方の入力側に
基準電位点抵抗Ｒ2を介して基準電位点に接続し、出力
側から負帰還抵抗Ｒ3を介し、また出力抵抗Ｒ5を経由し
正帰還抵抗Ｒ4を介してそれぞれ入力側に帰還接続し、
正帰還抵抗Ｒ4と出力抵抗Ｒ5の接続点を容量性スピーカ
としてセラミックスピーカ２ａを接続し、出力抵抗およ
び正帰還抵抗の和と基準電位点抵抗との比（Ｒ5＋Ｒ4）
／Ｒ2を、負帰還抵抗と入力抵抗との比Ｒ3／Ｒ1に一致
させている。更に、定電流源１ｂは図３に示すようにオ
ペアンプ４ａの一方の入力側に音声信号ｆ1が入力され
る入力抵抗Ｒ1を接続し、他方の入力側に基準電位点抵
抗Ｒ2を介して基準電位点に接続し、出力側から負帰還
抵抗Ｒ3を介し、また出力抵抗Ｒ5を経由し正帰還抵抗Ｒ
4を介してそれぞれ入力側に帰還接続し、出力抵抗Ｒ5を
容量性スピーカとしてのセラミックスピーカ２ａを接続
し、正帰還抵抗Ｒ4と出力抵抗Ｒ5の間にバッファ機能を
有するオペアンプ４ｂを介在し、出力抵抗および正帰還
抵抗の和と基準電位点抵抗との比（Ｒ5＋Ｒ4）／Ｒ2
を、負帰還抵抗と入力抵抗との比Ｒ3／Ｒ1に一致させて
いる。図２に示すように、定電流源１ａの入力抵抗Ｒ1
はオペアンプ４の一方の端子（−）と接続され、一方の
端子（−）は負帰還抵抗Ｒ3を介してオペアンプ４の出
力側と接続されている。また、一端が基準電位点に接続
された基準電位点抵抗Ｒ2の他端はオペアンプ４の他方
の端子（＋）と接続され、他方の端子（＋）は正帰還抵
抗Ｒ4と出力抵抗Ｒ5を介してオペアンプ４の出力側と接
続されている。正帰還抵抗Ｒ4と出力抵抗Ｒ5の接続点に
は一端が基準電位点に接続されたセラミックスピーカ２
ａの他端が接続されている。更に、図３に示すように、
定電流源１ｂの入力抵抗Ｒ1はオペアンプ４ａの一方の
端子（−）と接続され、一方の端子（−）は負帰還抵抗
Ｒ3を介してオペアンプ４ａの出力側と接続されてい
る。また、一端が基準電位点に接続された基準電位点抵
抗Ｒ2の他端はオペアンプ４ａの他方の端子（＋）と接
続され、他方の端子（＋）は正帰還抵抗Ｒ4を介してバ
ッファ機能を有するオペアンプ４ｂの出力側及び一方の
端子（−）と接続されている。オペアンプ４ｂの他方の
端子（＋）は出力抵抗Ｒ5を介してオペアンプ４ａの出
力側及び一端が基準電位点に接続されたセラミックスピ
ーカ２ａの他端が接続されている。定電流源１ａ、１ｂ
の出力インピーダンスＺAは数式（３）により求められ
る。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a preferred embodiment of a speaker drive circuit according to the present invention. As shown in FIG. 1, the speaker driving circuit according to the present invention includes an audio signal f1.
And a capacitive speaker 2 driven by the constant current source to change the output current according to the audio signal. The capacitive speaker is composed of a ceramic speaker 2a as shown in FIG. As shown in FIG. 2, the constant current source 1a has one input side of the operational amplifier 4 connected to an input resistor R1 to which an audio signal f1 is input, and the other input side connected to a reference potential point via a reference potential point resistor R2. Connected to the input side via the negative feedback resistor R3 from the output side, and via the output resistor R5 to the input side via the positive feedback resistor R4.
A ceramic speaker 2a is connected to the connection point between the positive feedback resistor R4 and the output resistor R5 as a capacitive speaker, and the ratio of the sum of the output resistance and the positive feedback resistor to the reference potential point resistor (R5 + R4)
/ R2 is made to match the ratio R3 / R1 between the negative feedback resistance and the input resistance. Further, as shown in FIG. 3, the constant current source 1b has one input side of the operational amplifier 4a connected to the input resistor R1 to which the audio signal f1 is input, and the other input side connected to the reference potential point resistor R2 via the reference potential point resistor R2. Connected from the output side via a negative feedback resistor R3, and via an output resistor R5 to a positive feedback resistor R3.
The output resistor R5 is connected to a ceramic speaker 2a as a capacitive speaker, and an operational amplifier 4b having a buffer function is interposed between the positive feedback resistor R4 and the output resistor R5. Ratio of the sum of the resistance and the positive feedback resistance to the reference potential point resistance (R5 + R4) / R2
Is matched with the ratio R3 / R1 between the negative feedback resistance and the input resistance. As shown in FIG. 2, the input resistance R1 of the constant current source 1a
Is connected to one terminal (-) of the operational amplifier 4, and one terminal (-) is connected to the output side of the operational amplifier 4 via the negative feedback resistor R3. The other end of the reference potential point resistor R2 having one end connected to the reference potential point is connected to the other terminal (+) of the operational amplifier 4, and the other terminal (+) is connected via a positive feedback resistor R4 and an output resistor R5. And is connected to the output side of the operational amplifier 4. A ceramic speaker 2 having one end connected to a reference potential point at a connection point between the positive feedback resistor R4 and the output resistor R5.
The other end of a is connected. Further, as shown in FIG.
The input resistor R1 of the constant current source 1b is connected to one terminal (-) of the operational amplifier 4a, and the one terminal (-) is connected to the output side of the operational amplifier 4a via the negative feedback resistor R3. The other end of the reference potential point resistor R2 having one end connected to the reference potential point is connected to the other terminal (+) of the operational amplifier 4a, and the other terminal (+) has a buffer function via the positive feedback resistor R4. Connected to the output side of the operational amplifier 4b and one terminal (−). The other terminal (+) of the operational amplifier 4b is connected via an output resistor R5 to the output side of the operational amplifier 4a and the other end of the ceramic speaker 2a whose one end is connected to a reference potential point. Constant current source 1a, 1b
Is obtained by equation (3).
【数３】 但し、ＲHは数式（４）により求めた合成抵抗値であ
る。(Equation 3) Here, RH is a combined resistance value obtained by Expression (4).
【数４】 ここで、（Ｒ5＋Ｒ4）／Ｒ2＝Ｒ3／Ｒ1とするとＲHは０
となり、数式（３）の定電流源１ａ、１ｂの出力インピ
ーダンスＺAは無限大となる。定電流源１ａ、１ｂの出
力インピーダンスＺAが無限大となると、定電流源１
ａ、１ｂは定電流源として動作する。定電流源１ａ、１
ｂが定電流源として動作すると、セラミックスピーカ２
ａに定電流源１ａ、１ｂから供給される電力は図４に示
すように横軸を音声信号ｆ1の範囲での周波数ｆ（Ｈ
ｚ）、縦軸をセラミックスピーカ２ａへの供給電力ＰA
（Ｗ）とすれば、に示す特性曲線となり低音域の供給
電力が増加する。この特性曲線は数式（５）により求
められる。(Equation 4) Here, if (R5 + R4) / R2 = R3 / R1, RH becomes 0
And the output impedance ZA of the constant current sources 1a and 1b in Expression (3) becomes infinite. When the output impedance ZA of the constant current sources 1a and 1b becomes infinite,
a and 1b operate as constant current sources. Constant current source 1a, 1
b operates as a constant current source, the ceramic speaker 2
As shown in FIG. 4, the power supplied from the constant current sources 1a and 1b to the frequency a is the frequency f (H
z), the vertical axis indicates the power PA supplied to the ceramic speaker 2a.
If (W) is set, the characteristic curve shown in the following will be obtained, and the supply power in the low frequency range will increase. This characteristic curve is obtained by Expression (5).
【数５】 但しＩAは定電流源１ａ、１ｂの出力電流で一定、ＺBは
セラミックスピーカ２ａのインピーダンスである。この
ようなオペアンプ４または４ａ、４ｂで構成され、出力
インピーダンスが無限大に設定された定電流源１ａ、ま
たは１ｂへ音声信号ｆ1が入力されると、セラミックス
ピーカ２ａの出力は図５のに示す動作特性となり、従
来のに示す動作特性に比べて低音域では電気／音響変
換効率が高くなる。なお、図５に示すセラミックスピー
カ２ａの周波数／音圧レベル特性図の横軸は周波数ｆ
（Ｈｚ）、縦軸は音圧レベル（ｄＢ）である。負荷の大
きいセラミックスピーカ２ａを駆動する場合は、図３に
示すオペアンプ４ａとバッファ機能を有するオペアンプ
４ｂを設けた定電流源１ｂが適している。叙上の定電流
源１をトランスコンダクタンス・アンプ等のＩＣで構成
してもよい。(Equation 5) Here, IA is constant at the output current of the constant current sources 1a and 1b, and ZB is the impedance of the ceramic speaker 2a. When the audio signal f1 is inputted to the constant current source 1a or 1b which is constituted by such operational amplifiers 4 or 4a and 4b and whose output impedance is set to infinity, the output of the ceramic speaker 2a is shown in FIG. It becomes an operation characteristic, and the electric / acoustic conversion efficiency is higher in a low sound range than the operation characteristic shown in the related art. The horizontal axis of the frequency / sound pressure level characteristic diagram of the ceramic speaker 2a shown in FIG.
(Hz), the vertical axis is the sound pressure level (dB). When driving the ceramic speaker 2a having a large load, the constant current source 1b provided with the operational amplifier 4a and the operational amplifier 4b having a buffer function shown in FIG. 3 is suitable. The above-described constant current source 1 may be constituted by an IC such as a transconductance amplifier.
【発明の効果】以上の説明から明らかなように、本発明
のスピーカ駆動回路によれば、低音域での電気／音響変
換効率が改善され、従来のスピーカと比較して経済性が
向上し、 また定電流源を安価な市販のオペアンプで構
成でき、更に定電流源を安価な市販のオペアンプで構成
でき、駆動電流が増加する。As is apparent from the above description, according to the speaker driving circuit of the present invention, the electric / acoustic conversion efficiency in the low frequency range is improved, and the economic efficiency is improved as compared with the conventional speaker. Further, the constant current source can be constituted by an inexpensive commercially available operational amplifier, and the constant current source can be constituted by an inexpensive commercially available operational amplifier, so that the driving current increases.
【図１】本発明によるスピーカ駆動回路の一実施例を示
す構成図。FIG. 1 is a configuration diagram showing one embodiment of a speaker drive circuit according to the present invention.
【図２】本発明によるスピーカ駆動回路の他の一実施例
を示す回路図。FIG. 2 is a circuit diagram showing another embodiment of the speaker drive circuit according to the present invention.
【図３】本発明によるスピーカ駆動回路の他の一実施例
を示す回路図。FIG. 3 is a circuit diagram showing another embodiment of the speaker drive circuit according to the present invention.
【図４】本発明によるスピーカ駆動回路に係わる供給電
力特性図。FIG. 4 is a supply power characteristic diagram relating to the speaker drive circuit according to the present invention.
【図５】本発明によるスピーカ駆動回路に係わる周波数
／音圧レベル特性図。FIG. 5 is a frequency / sound pressure level characteristic diagram relating to the speaker drive circuit according to the present invention.
【図６】従来のスピーカ駆動回路の回路図。FIG. 6 is a circuit diagram of a conventional speaker drive circuit.
【図７】従来のスピーカ駆動回路におけるセラミックス
ピーカの周波数特性図。FIG. 7 is a frequency characteristic diagram of a ceramic speaker in a conventional speaker drive circuit.
【図８】従来のスピーカ駆動回路の供給電力特性図。FIG. 8 is a power supply characteristic diagram of a conventional speaker drive circuit.
１、１ａ、１ｂ・・・・・・定電流源 ２・・・・・・容量性スピーカ ２ａ・・・・・・セラミックスピーカ ４、４ａ・・・・・・オペアンプ ４ｂ・・・・・・バッファ機能を有するオペアンプ ｆ1・・・・・・音声信号 Ｒ1・・・・・・入力抵抗 Ｒ2・・・・・・基準電位点抵抗 Ｒ3・・・・・・負帰還抵抗 Ｒ4・・・・・・正帰還抵抗 Ｒ5・・・・・・出力抵抗 1, 1a, 1b ... constant current source 2 ... capacitive speaker 2a ... ceramic speaker 4, 4a ... operational amplifier 4b ... Operational amplifier having a buffer function f1 ... Audio signal R1 ... Input resistance R2 ... Reference potential point resistance R3 ... Negative feedback resistance R4 ...・ Positive feedback resistor R5 ・ ・ ・ ・ ・ ・ Output resistance
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平５−327360（ＪＰ，Ａ) 特開 平４−132497（ＪＰ，Ａ) 特公 昭56−7360（ＪＰ，Ｂ２) (58)調査した分野(Int.Cl.7，ＤＢ名) H04R 3/00 310 H04M 1/60 H04R 17/00 H04R 19/02 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-327360 (JP, A) JP-A-4-132497 (JP, A) JP-B-56-7360 (JP, B2) (58) Field (Int.Cl. 7 , DB name) H04R 3/00 310 H04M 1/60 H04R 17/00 H04R 19/02
Claims (2)
により出力電流を変化させる定電流源（１）と、前記定
電流源により駆動される容量性スピーカ（２）とを備
え、前記容量性スピーカは、セラミックスピーカ（２
ａ）で構成され、 前記定電流源はオペアンプ（４）の一方の入力側に前記
音声信号が入力される入力抵抗（Ｒ1）を接続し、他方
の入力側に基準電位点抵抗（Ｒ2）を介して基準電位点
に接続し、出力側から負帰還抵抗（Ｒ3）を介し、また
出力抵抗（Ｒ5）を経由し正帰還抵抗（Ｒ4）を介してそ
れぞれ入力側に帰還接続し、前記正帰還抵抗と前記出力
抵抗の接続点を前記容量性スピーカに接続し、前記出力
抵抗および前記正帰還抵抗の和と前記基準電位点抵抗と
の比（（Ｒ5＋Ｒ4）／Ｒ2）を、前記負帰還抵抗と前記
入力抵抗との比（Ｒ3／Ｒ1）に一致させた ことを特徴と
するスピーカ駆動回路。An audio signal (f1) is inputted and said audio signal is inputted.
A constant current source (1) for changing the output current according to
And a capacitive speaker (2) driven by a current source.
The capacitive speaker is a ceramic speaker (2
a) wherein the constant current source is connected to one input side of an operational amplifier (4).
Connect the input resistor (R1) to which the audio signal is input, and connect
The reference potential point via the reference potential point resistor (R2)
And from the output side via a negative feedback resistor (R3),
Via the output resistance (R5) and the positive feedback resistance (R4)
Feedback connection to the input side, the positive feedback resistor and the output
A resistor connection point is connected to the capacitive speaker, and the output
Resistance and the sum of the positive feedback resistance and the reference potential point resistance,
The ratio ((R5 + R4) / R2) is calculated by subtracting the negative feedback resistance
A speaker drive circuit characterized by having a ratio (R3 / R1) to an input resistance .
により出力電流を変化させる定電流源（１）と、前記定
電流源により駆動される容量性スピーカ（２）とを備
え、前記容量性スピーカは、セラミックスピーカ（２
ａ）で構成され、 前記定電流源は、オペアンプ（４ａ）の一方の入力側に
前記音声信号が入力される入力抵抗（Ｒ1）を接続し、
他方の入力側に基準電位点抵抗（Ｒ2）を介して基準電
位点に接続し、出力側から負帰還抵抗（Ｒ3）を介し、
また出力抵抗（Ｒ5）を経由し正帰還抵抗（Ｒ4）を介し
てそれぞれ入力側に帰還接続し、前記出力抵抗を前記容
量性スピーカに接続し、前記正帰還抵抗と前記出力抵抗
間にバッファ機能を有するオペアンプ（４ｂ）を介在
し、前記出力抵抗および前記正帰還抵抗の和と前記基準
電位点抵抗との比（（Ｒ5＋Ｒ4）／Ｒ2）を、前記負帰
還抵抗と前記入力抵抗との比（Ｒ3／Ｒ1）に一致させた
ことを特徴とするスピーカ駆動回路。2. An audio signal (f1) is inputted and said audio signal
A constant current source (1) for changing the output current according to
And a capacitive speaker (2) driven by a current source.
The capacitive speaker is a ceramic speaker (2
a) wherein the constant current source is connected to one input side of an operational amplifier (4a).
Connecting an input resistor (R1) to which the audio signal is input;
A reference voltage is connected to the other input side via a reference potential point resistor (R2).
Connected from the output side, from the output side through a negative feedback resistor (R3),
Also, via the output resistance (R5) and the positive feedback resistance (R4)
To the input side, and connect the output resistance to the
Connected to a quantitative speaker, the positive feedback resistance and the output resistance
Operational amplifier (4b) with buffer function interposed between
The sum of the output resistance and the positive feedback resistance and the reference
The ratio to the potential point resistance ((R5 + R4) / R2) is calculated by the negative feedback.
A speaker drive circuit characterized in that a ratio (R3 / R1) between the feedback resistance and the input resistance is matched .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17731494A JP3168120B2 (en) | 1994-07-28 | 1994-07-28 | Speaker drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17731494A JP3168120B2 (en) | 1994-07-28 | 1994-07-28 | Speaker drive circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0847077A JPH0847077A (en) | 1996-02-16 |
| JP3168120B2 true JP3168120B2 (en) | 2001-05-21 |
Family
ID=16028822
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17731494A Expired - Lifetime JP3168120B2 (en) | 1994-07-28 | 1994-07-28 | Speaker drive circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3168120B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016082520A (en) * | 2014-10-21 | 2016-05-16 | 邦男 中山 | Current drive circuit |
| JP7393091B2 (en) * | 2014-10-21 | 2023-12-06 | 邦男 中山 | current drive device |
-
1994
- 1994-07-28 JP JP17731494A patent/JP3168120B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0847077A (en) | 1996-02-16 |
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