JPH063452Y2 - Current supply circuit - Google Patents
Current supply circuitInfo
- Publication number
- JPH063452Y2 JPH063452Y2 JP2569186U JP2569186U JPH063452Y2 JP H063452 Y2 JPH063452 Y2 JP H063452Y2 JP 2569186 U JP2569186 U JP 2569186U JP 2569186 U JP2569186 U JP 2569186U JP H063452 Y2 JPH063452 Y2 JP H063452Y2
- Authority
- JP
- Japan
- Prior art keywords
- current
- input terminal
- load
- voltage
- circuit
- 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
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Description
【考案の詳細な説明】 〔産業上の利用分野〕 本考案は、入力電流を受けて、負荷回路に上記入力電流
変化に比例した電流を供給する電流供給回路に関するも
のである。DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a current supply circuit which receives an input current and supplies a current proportional to the change in the input current to a load circuit.
従来例えば電気信号を空気圧信号に変換する電気−空気
圧変換器等において、零点の調整およびスパンの調整
は、純機械的に、レバー比を変えることなどによって行
なわれてきた。Conventionally, for example, in an electro-pneumatic converter for converting an electric signal into a pneumatic signal, the adjustment of the zero point and the adjustment of the span have been performed purely mechanically by changing the lever ratio.
しかし、このような機械的な、調整方式は、機構そ複雑
になるとともに、調整感度が高くなることから調整作業
が難しいという問題があった。これらの調整を電気的に
行なうには、フラッパを駆動する電磁コイルの励磁電流
を調整することが考えられる。例えば、電磁コイルに並
列に可変抵抗を接続し、その抵抗値を変化させることに
より、電磁コイルに流れる電流を調整することができ
る。However, such a mechanical adjustment method has a problem that the adjustment work is difficult because the mechanism becomes complicated and the adjustment sensitivity becomes high. In order to make these adjustments electrically, it is conceivable to adjust the exciting current of the electromagnetic coil that drives the flapper. For example, it is possible to adjust the current flowing through the electromagnetic coil by connecting a variable resistor in parallel to the electromagnetic coil and changing the resistance value.
ところが、コイルは通常銅線からできており、その抵抗
値は大きな温度依存性を示すため、温度によって特性が
変化してしまう。However, the coil is usually made of copper wire, and its resistance value has a large temperature dependence, so that the characteristics change depending on the temperature.
本考案の電流供給回路は、負荷の一端と電流入力端子の
一端との間に直列に接続されたスパン調整回路と、電流
入力端子の他端とスパン調整回路と負荷との接続点に接
続されるとともに入力電流から常に一定値の電流を分流
する零点調整用の可変インピーダンス素子と、この可変
インピーダンス素子と負荷との間に接続され電流入力端
子間の電圧を一定値に保つ定電圧回路とを有し、スパン
調整回路内には、一端及び他端が各々電流入力端子の一
端と負荷の一端との間に接続されたインピーダンス素子
と、このインピーダンス素子と負荷との接続点に非反転
入力端子を接続した第１の演算増幅器と、この第１の演
算増幅器の反転入力端子および出力端子と上記インピー
ダンス素子の一端との間に接続された可変インピーダン
ス素子とを有すると共に、定電圧回路には、電流入力端
子の他端と負荷の他端との間に直列に挿入されたトラン
ジスタと、電流入力端子間電圧を分圧する分圧回路と、
この分圧回路による分圧出力を一方の入力とし基準電圧
を他方の入力とするとともに出力を上記トランジスタの
制御信号とする第２の演算増幅器とを有する。The current supply circuit of the present invention is connected to a span adjustment circuit connected in series between one end of a load and one end of a current input terminal, and a connection point between the other end of the current input terminal, a span adjustment circuit and a load. A variable impedance element for zero point adjustment that constantly diverts a constant value current from the input current, and a constant voltage circuit connected between this variable impedance element and the load to keep the voltage between the current input terminals at a constant value. In the span adjustment circuit, one end and the other end are respectively connected between one end of the current input terminal and one end of the load, and a non-inverting input terminal at the connection point of this impedance element and the load. And a variable impedance element connected between the inverting input terminal and the output terminal of the first operational amplifier and one end of the impedance element. Both the constant-voltage circuit, a transistor inserted in series between the other ends of the load current input terminals, a voltage dividing circuit for dividing a voltage between current input terminal,
It has a second operational amplifier which uses the voltage-divided output by the voltage dividing circuit as one input and the reference voltage as the other input, and uses the output as a control signal for the transistor.
負荷、例えば前述した電磁コイルのインピーダンスの大
小、のみならず定電圧回路における電流消費などにも影
響されず、入力電流に対してリニアに対応した負荷電流
が供給される。A load current linearly corresponding to the input current is supplied without being influenced by the load, for example, the magnitude of the impedance of the electromagnetic coil described above, and the current consumption in the constant voltage circuit.
第１図は本考案の一実施例を示す回路図である。本実施
例は第２図に示すような電気−空気圧変換器に適用した
例で、負荷として電磁コイル１を有している。FIG. 1 is a circuit diagram showing an embodiment of the present invention. This embodiment is an example applied to an electro-pneumatic converter as shown in FIG. 2, and has an electromagnetic coil 1 as a load.
第２図において、永久磁石２に対応して配置された電磁
コイル１に入力電流Ｉに比例した電流ＩＣを流し、電気
信号をレバー３の動きに変換してフラッパ４とノズル５
との間隔を変え、ノズル背圧を変化させる。ノズル背圧
の変化は、パイロットリレー６で増幅され出力空気圧Ｐ
ｏとして取り出される。７は復原機構としてのベロー
ズ、Ｐｓは供給空気圧を示す。In FIG. 2, a current I C proportional to an input current I is passed through an electromagnetic coil 1 arranged corresponding to a permanent magnet 2 to convert an electric signal into a movement of a lever 3 and a flapper 4 and a nozzle 5
Change the interval between and to change the nozzle back pressure. The change in the nozzle back pressure is amplified by the pilot relay 6 and the output air pressure P
It is taken out as o. 7 is a bellows as a restoring mechanism, and Ps is a supply air pressure.
ここで、入力電気信号は４〜20mAの電流Ｉとして与えら
れるが、これを第１図に示す回路で所定スパンの励磁電
流に変換し電磁コイル１に供給する。Here, the input electric signal is given as a current I of 4 to 20 mA, which is converted into an exciting current having a predetermined span in the circuit shown in FIG. 1 and supplied to the electromagnetic coil 1.
第１図において、本実施例の電流供給回路は、入力電流
を分流する零点調整用の可変抵抗ＲＺ、定電圧回路１１
およびスパン調整回路１２からなる。In FIG. 1, the current supply circuit of the present embodiment includes a variable resistor R Z for adjusting a zero point for shunting an input current, a constant voltage circuit 11.
And a span adjusting circuit 12.
定電圧回路１１は、電磁コイル１に直列に挿入されたト
ランジスタＱ１、入力端子間電圧を分圧する抵抗Ｒ１，
Ｒ２の直列回路およびこれら抵抗Ｒ１，Ｒ２の接続点に
非反転出力端子を接続し、反転入力端子を基準電圧源Ｖ
ｓに接続しかつ出力端子をトランジスタＱ１のベースに
接続した演算増幅器OP1からなり、電流入力端子間の電
圧Ｖｉを一定値に保つ。The constant voltage circuit 11 includes a transistor Q 1 inserted in series in the electromagnetic coil 1, a resistor R 1 that divides a voltage between input terminals,
Connect the non-inverting output terminal to the series circuit and the connecting point of the resistors R 1, R 2 of R 2, a reference voltage source V to the inverting input terminal
It consists of an operational amplifier OP 1 connected to s and whose output terminal is connected to the base of the transistor Q 1 to keep the voltage Vi across the current input terminals at a constant value.
一方、スパン調整回路１２は、零点調整用可変抵抗器Ｒ
Ｚおよび定電圧回路１１より前段に位置し、電磁コイル
１の、トランジスタＱ１の接続端と反対側に直列に接続
された抵抗ＲＣ、この抵抗ＲＣと電磁コイル１との接続
点に非反転入力端子を接続したボルテツジホロワ接続の
演算増幅器OP2およびこの演算増幅器OP2の出力端子と抵
抗ＲＣの他端との間に接続された可変抵抗ＲＢによって
構成される。On the other hand, the span adjusting circuit 12 includes a variable resistor R for adjusting the zero point.
A resistor R C , which is located in front of Z and the constant voltage circuit 11 and is connected in series on the opposite side of the electromagnetic coil 1 from the connection end of the transistor Q 1 , is not connected to the connection point between the resistor R C and the electromagnetic coil 1. constituted by a variable resistor R B connected between the inverting input operational amplifier OP 2 and the output terminal of the operational amplifier OP 2 terminal Borutetsujihorowa connection was connected to the other end of the resistor R C.
上記構成において、可変抵抗ＲＢを流れる電流をＩＢ、
可変抵抗ＲＺを流れる電流をＩＺ、電磁コイル１および
抵抗ＲＬを流れる電流をＩＬとし抵抗Ｒ１，Ｒ２に流れ
る電流および演算増幅器OP1,OP2に流れる電流のうちＩ
Ｂを除く電流をまとめてＩ１とすると、入力電流Ｉは、 Ｉ＝ＩＢ＋ＩＬ＋ＩＺ＋Ｉ１ と表わせる。ここで、可変抵抗ＲＢ，ＲＺ，ＲＣの抵抗
値をそれぞれｒＢ，ｒＺ，ｒＣとして、 より、 したがって、 ただし 今、入力電流の最大値（本実施例では20mA）をImaX、最
小値（本実施例では4mA）をIminとして、それぞれその
ときの電流ＩＬの値ＩＬmax，ＩＬminは、 ＩＬmax＝K Imax−IZO ＩＬmin＝K Imin−IZO であることから、スパンＩＬ ＳＰＡＮは、 一方、零電流IZOは、上述したように したがって可変抵抗ＲＢの抵抗値ｒＢを変化させること
によりスパン調整が行なえるとともに、可変抵抗ＲＺの
抵抗値ｒＺを変化させることにより零点調整が行なえ
る。In the above configuration, the current flowing through the variable resistor R B is I B ,
Let I Z be the current flowing through the variable resistor R Z , I L be the current flowing through the electromagnetic coil 1 and the resistor R L , and I be the current flowing through the resistors R 1 and R 2 and the current flowing through the operational amplifiers OP 1 and OP 2.
When the currents except B are collectively I 1 , the input current I can be expressed as I = I B + I L + I Z + I 1 . Here, the resistance values of the variable resistors R B , R Z , and R C are r B , r Z , and r C , respectively, Than, Therefore, However Now, assuming that the maximum value (20 mA in this embodiment) of the input current is ImaX and the minimum value (4 mA in this embodiment) is Imin, the values I L max and I L min of the currents I L at that time are I L Since max = K Imax−I ZO I L min = K Imin−I ZO , the span I L SPAN is On the other hand, the zero current I ZO is as described above. Thus with perform span adjustment by changing the resistance value r B of the variable resistor R B, perform the zero point adjustment by changing the resistance value r Z of the variable resistor R Z.
このように本実施例によれば電磁コイル１のインピーダ
ンスにかかわらず、入力電流Ｉに応じた励磁電流ＩＬが
得られるとともに、その電流値は本電流供給回路自体で
消費する電流値に応じ常に一定比率に制御されたものと
なるため、入力電流が小さい場合に動作が不安定となる
ようなことがない。Thus regardless of the impedance of the electromagnetic coil 1 according to this embodiment, the exciting current I L with obtained according to the input current I, always according to the current value and the current value consumed in the current supply circuit itself Since it is controlled at a constant ratio, the operation does not become unstable when the input current is small.
上述した実施例において、定電圧回路１１の構成は、例
えば第３図に示すようにしてもよい。すなわち、この場
合、演算増幅器OP1はその反転入力端子を抵抗Ｒ１とＲ
２との接続点に接続するとともにその非反転入力端子を
基準電圧源ＶＳに接続してある。In the above-described embodiment, the configuration of the constant voltage circuit 11 may be as shown in FIG. 3, for example. That is, in this case, the operational amplifier OP 1 has its inverting input terminal connected to the resistors R 1 and R 2.
2 and the non-inverting input terminal thereof is connected to the reference voltage source V S.
同様にスパン調整回路１２は第４図に示すように構成し
てもよい。同図において、演算増幅器OP2の出力端子は
第１図の例のように非反転入力端子に直接接続される代
りにトランジスタＱ２のベースに接続され、トランジス
タＱ２のエミッタが反転入力端子および可変抵抗ＲＢに
接続されている。Similarly, the span adjusting circuit 12 may be configured as shown in FIG. In the figure, the output terminal of the operational amplifier OP 2 is connected to the base of the transistor Q 2 instead of being directly connected to the non-inverting input terminal as in the example of FIG. 1, and the emitter of the transistor Q 2 is connected to the inverting input terminal and It is connected to the variable resistor R B.
また、トランジスタＱ１，Ｑ２はFETを用いてもよい。In addition, FETs may be used for the transistors Q 1 and Q 2 .
以上、電気−空気圧変換器において励磁電流を得る場合
について説明したが、本考案はこれに限定されるもので
はなく、所定幅で変化する入力電流を受けて、負荷に上
記入力電流に比例した電流を供給する各種駆動回路等に
一般に適用可能なものである。The case where an exciting current is obtained in the electro-pneumatic converter has been described above, but the present invention is not limited to this, and the load receives an input current that changes in a predetermined width, and a current proportional to the input current. It is generally applicable to various drive circuits for supplying the.
以上説明したように、本考案によれば、電気的な方法で
零調・スパン調が行なえ、機械的な調整を必要としない
ため機械的構成がシンプルて信頼性が向上するととも
に、組立および調整が容易となる。また、温度等による
負荷インピーダンスの変動にかかわらず、入力電流に比
例した負荷電流が供給できるため、調整精度を向上でき
る。As described above, according to the present invention, zero adjustment and span adjustment can be performed by an electrical method, and mechanical adjustment is not required, so that the mechanical structure is simple and reliability is improved, and assembling and adjustment are performed. Will be easier. Further, since the load current proportional to the input current can be supplied regardless of the change of the load impedance due to temperature or the like, the adjustment accuracy can be improved.
特に、例えばプロセス制御系において、発信器や制御機
器から出力される４〜20mAあるいは10〜50mA等の電流信
号を受信しその信号値に応じた動作を行なう負荷として
の受信器が各種ある場合でも、個々の受信器の具体的な
構成の違いにかかわらず、調整機構は同一で良いため、
保守作業等が容易となる。In particular, for example, in a process control system, even if there are various receivers as loads that receive a current signal of 4 to 20 mA or 10 to 50 mA output from an oscillator or a control device and operate according to the signal value. , Regardless of the difference in the specific configuration of each receiver, the adjustment mechanism can be the same,
Maintenance work becomes easy.
第１図は本考案の一実施例を示す回路図、第２図はそれ
を適用した電気−空気圧変換器を示す構成図、第３図お
よび第４図はそれぞれ本考案の他の実施例を示す回路図
である。 １１……定電圧回路、１２……スパン調整回路、OP1,OP
2……演算増幅器、Ｑ１……トランジスタ、Ｒ１，
Ｒ２，ＲＣ……抵抗、ＲＢ，ＲＺ……可変抵抗、ＶＳ…
…基準電圧源。FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an electro-pneumatic converter to which the same is applied, and FIGS. 3 and 4 are other embodiments of the present invention. It is a circuit diagram shown. 11: constant voltage circuit, 12: span adjustment circuit, OP 1 , OP
2 ...... operational amplifier, Q 1 ...... transistor, R 1,
R 2, R C ...... resistor, R B, R Z ...... variable resistor, V S ...
… Reference voltage source.
Claims (1)
幅で変化する入力電流を電流入力端子から受けて負荷に
上記入力電流に比例した電流を供給する電流供給回路に
おいて、負荷の一端と電流入力端子の一端との間に直列
に接続されたスパン調整回路と、電流入力端子の他端と
スパン調整回路と負荷との接続点に接続されるとともに
入力電流から常に一定値の電流を分流する零点調整用の
可変インピーダンス素子と、この可変インピーダンス素
子と負荷との間に接続され電流入力端子間の電圧を一定
値に保つ定電圧回路とを有し、スパン調整回路は、一端
及び他端が各々電流入力端子の一端と負荷の一端との間
に接続されたインピーダンス素子と、このインピーダン
ス素子と負荷との接続点に非反転入力端子を接続した第
１の演算増幅器と、この第１の演算増幅器の反転入力端
子および出力端子と上記インピーダンス素子の一端との
間に接続された可変インピーダンス素子とを含み、定電
圧回路は、電流入力端子の他端と負荷の他端との間に直
列に挿入されたトランジスタと、電流入力端子間電圧を
分圧する分圧回路と、この分圧回路による分圧出力を一
方の入力とし基準電圧を他方の入力とするとともに出力
を上記トランジスタの制御信号とする第２の演算増幅器
とを含むことを特徴とする電流供給回路。1. A current supply circuit, which is connected between a current input terminal and a load, receives an input current varying with a predetermined width from the current input terminal, and supplies a current proportional to the input current to the load. Is connected in series between the current input terminal and one end of the current input terminal, and is connected to the connection point between the other end of the current input terminal, the span adjustment circuit and the load, and a constant value current is always output from the input current. It has a variable impedance element for shunting a zero point and a constant voltage circuit connected between the variable impedance element and a load to keep the voltage between the current input terminals at a constant value. An impedance element whose ends are respectively connected between one end of the current input terminal and one end of the load; and a first operational amplifier having a non-inverting input terminal connected to a connection point between the impedance element and the load. The constant voltage circuit includes a variable impedance element connected between the inverting input terminal and the output terminal of the first operational amplifier and one end of the impedance element, and the constant voltage circuit includes the other end of the current input terminal and the other end of the load. A transistor inserted in series between the two, a voltage dividing circuit for dividing the voltage between the current input terminals, a voltage division output by this voltage dividing circuit as one input and a reference voltage as the other input, and the output is the above transistor. And a second operational amplifier which is used as the control signal of 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2569186U JPH063452Y2 (en) | 1986-02-26 | 1986-02-26 | Current supply circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2569186U JPH063452Y2 (en) | 1986-02-26 | 1986-02-26 | Current supply circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62138215U JPS62138215U (en) | 1987-08-31 |
| JPH063452Y2 true JPH063452Y2 (en) | 1994-01-26 |
Family
ID=30826083
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2569186U Expired - Lifetime JPH063452Y2 (en) | 1986-02-26 | 1986-02-26 | Current supply circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH063452Y2 (en) |
-
1986
- 1986-02-26 JP JP2569186U patent/JPH063452Y2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62138215U (en) | 1987-08-31 |
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