JPS6351269B2 - - Google Patents
Info
- Publication number
- JPS6351269B2 JPS6351269B2 JP3137879A JP3137879A JPS6351269B2 JP S6351269 B2 JPS6351269 B2 JP S6351269B2 JP 3137879 A JP3137879 A JP 3137879A JP 3137879 A JP3137879 A JP 3137879A JP S6351269 B2 JPS6351269 B2 JP S6351269B2
- Authority
- JP
- Japan
- Prior art keywords
- resistor
- operational amplifier
- contact
- capacitor
- input terminal
- 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
Links
- 239000003990 capacitor Substances 0.000 claims description 12
- 238000001514 detection method Methods 0.000 description 8
- 230000005684 electric field Effects 0.000 description 5
- 230000004907 flux Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
Landscapes
- Measurement Of Current Or Voltage (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
Description
【発明の詳細な説明】
被測定物の表面電位と対応した電界を、回転セ
クタ、あるいは音叉等によつて変調し、この変調
された電界中に置かれた検知電極より得た電束電
流を電流電圧変換器によつて電圧に変換するよう
な構成部分を備えている非接触型電位計におい
て、測定系中に含まれている機構部分や電気回路
中に存在する異種金属の接触部分で発生する接触
電位差は、測定結果に妨害を与えるノイズとな
る。[Detailed description of the invention] An electric field corresponding to the surface potential of the object to be measured is modulated by a rotating sector or a tuning fork, and the electric flux current obtained from a sensing electrode placed in this modulated electric field is In non-contact electrometers that are equipped with components that convert into voltage using a current-voltage converter, this occurs at the mechanical parts included in the measurement system or at the contact parts of dissimilar metals in the electrical circuit. This contact potential difference becomes noise that interferes with the measurement results.
従来、上記のようなノイズを減少させるための
技術手段としては、例えば特開昭47−16171号公
報に開示されているように、検知電極に抵抗を介
して補償用の電位を与えて、接触電位差等によつ
て測定値中に生じる誤差を減少させる、というも
のがあるが、この公知の技術手段を適用した場合
には、検知電極に抵抗を接続することによる増幅
器の入力インピーダンスの低下と、抵抗を付加し
たことで生じる入力容量の増加による入力インピ
ーダンスの低下によつて非接触電位計の感度を低
下させてしまうことが問題となつた。 Conventionally, as a technical means for reducing the above-mentioned noise, for example, as disclosed in Japanese Patent Laid-Open No. 16171/1983, a compensation potential is applied to the sensing electrode via a resistor, and contact is made. There is a method of reducing errors that occur in measured values due to potential differences, etc., but when this known technical means is applied, it is possible to reduce the input impedance of the amplifier by connecting a resistor to the sensing electrode, A problem has arisen in that the sensitivity of the non-contact electrometer decreases due to a decrease in input impedance due to an increase in input capacitance caused by adding a resistor.
本発明は、非反転の増幅器として用いられてい
る演算増幅器によつて構成されている電流電圧変
換器を有する非接触電位計において、前記した演
算増幅器の反転入力端子と出力端子との間に抵
抗、または抵抗とコンデンサとの並列接続回路を
接続し、また、前記の演算増幅器の反転入力端子
を抵抗を介して可変電圧源に接続してなる非接触
型電位計におけるノイズ減少回路を提供して、従
来の問題点を解消したものであり、以下、添付図
面を参照して本発明の非接触型電位計におけるノ
イズ減少回路の具体的な内容について詳細に説明
する。 The present invention provides a non-contact electrometer having a current-voltage converter constituted by an operational amplifier used as a non-inverting amplifier, in which a resistor is connected between an inverting input terminal and an output terminal of the operational amplifier. , or a parallel connection circuit of a resistor and a capacitor, and the inverting input terminal of the operational amplifier is connected to a variable voltage source via a resistor to provide a noise reduction circuit in a non-contact electrometer. , the conventional problems have been solved, and the specific contents of the noise reduction circuit in the non-contact electrometer of the present invention will be explained in detail below with reference to the accompanying drawings.
添付図面は本発明のノイズ減少回路を含んで構
成された非接触型電位計の要部の構成を示す回路
図であつて、図中において、Ｍは被測定物、Ｓは
シールド面、VSは回転セクタ、あるいは音叉の
ような電界変調手段、Ｅは検知電極、OAは演算
増幅器であつて、被測定物Ｍの表面電位と対応す
る電界はそれがシールド面Ｓに穿設された孔Sa
を通して検知電極Ｅに到達する途中に設けられた
変調手段VSによつて変調されることにより、検
知電極Ｅには変調手段VSにおける変調周波数と
対応した周波数を有する電束電流が流入する。 The attached drawing is a circuit diagram showing the main part of a non-contact electrometer including the noise reduction circuit of the present invention. In the drawing, M is the object to be measured, S is the shield surface, and VS is the An electric field modulating means such as a rotating sector or a tuning fork, E is a detection electrode, and OA is an operational amplifier.
By being modulated by the modulation means VS provided on the way to the detection electrode E through the detection electrode E, an electric flux current having a frequency corresponding to the modulation frequency in the modulation means VS flows into the detection electrode E.
前記の検知電極Ｅに流入した電束電流は、非反
転増幅器として用いられている演算増幅器OAに
よつて構成されている電流電圧変換器によつて電
圧に変換されて出力端子Ｏに送出されると共に、
シールド面Ｓにも与えられる。 The electric flux current flowing into the sensing electrode E is converted into a voltage by a current-voltage converter constituted by an operational amplifier OA used as a non-inverting amplifier, and sent to the output terminal O. With,
It is also given to the shield surface S.
ところで、前記した構成部分中には異種金属の
接触部分が必らず存在しているが、前記の接触部
分に生じる接触電位差に基づく電界は、被測定物
Ｍと検知電極Ｅとの間の電界に重畳された状態の
ものとして変調手段VSと検知電極Ｅとの間に現
われるから、前記した接触電位差は被測定物によ
る信号に対してノイズ成分として測定結果中に含
まれてしまうのであり、検知電極Ｅから演算増幅
器OAの非反転入力端子に与えられる入力信号は
被測定物Ｍの表面電位に基づく信号と、接触電位
差に基づく信号との和信号となつている。 By the way, although there is always a contact portion between different metals in the above-mentioned components, the electric field based on the contact potential difference generated at the contact portion is the electric field between the object to be measured M and the sensing electrode E. Since it appears between the modulation means VS and the detection electrode E as a superimposed state, the above-mentioned contact potential difference is included in the measurement result as a noise component with respect to the signal from the object to be measured, and the detection The input signal applied from the electrode E to the non-inverting input terminal of the operational amplifier OA is a sum signal of a signal based on the surface potential of the object to be measured M and a signal based on the contact potential difference.
演算増幅器OAは、非反転入力端子と接地との
間に抵抗R3と抵抗R4との直列接続回路が設けら
れており、また、前記した抵抗R3とR4との接続
点と演算増幅器の出力端子Ｏとの間にはブートス
トラツプ用のコンデンサC2が接続されていて、
検知電極Ｅから非反転入力端子の入力側を見たイ
ンピーダンスが極めて高くなるようになされてい
る。 The operational amplifier OA is provided with a series connection circuit of a resistor R 3 and a resistor R 4 between the non-inverting input terminal and the ground, and a connection point between the resistors R 3 and R 4 described above and the operational amplifier. A bootstrap capacitor C2 is connected between the output terminal O of the
The impedance viewed from the detection electrode E to the input side of the non-inverting input terminal is extremely high.
演算増幅器OAの反転入力端子と出力端子Ｏと
の間には、抵抗R2とコンデンサC1との並列接続
回路が接続されており、また、前記した演算増幅
器OAの反転入力端子には抵抗R1を介して可変電
圧源VRに接続されている。図示の例において、
可変電圧源VRは、各一端子が正、負電源＋、−
に接続された可変抵抗器VRによつて構成されて
おり、可変抵抗器VRの摺動子には、その摺動位
置に応じて正、負の各異なる電圧値が得られるの
であり、したがつて、前記の演算増幅器OAの反
転入力端子に接続された抵抗R1には、可変抵抗
器VRの摺動子の摺動に応じて所望の極性及び電
圧値を有する電流電圧が与えられる。 A parallel connection circuit consisting of a resistor R 2 and a capacitor C 1 is connected between the inverting input terminal and the output terminal O of the operational amplifier OA, and a resistor R is connected to the inverting input terminal of the operational amplifier OA. 1 is connected to the variable voltage source VR. In the illustrated example,
The variable voltage source VR has one terminal for each positive and negative power supply +, -.
The slider of the variable resistor VR receives different positive and negative voltage values depending on its sliding position. Accordingly, a current voltage having a desired polarity and voltage value is applied to the resistor R1 connected to the inverting input terminal of the operational amplifier OA in accordance with the sliding of the slider of the variable resistor VR.
今、可変抵抗VRの摺動子と接地との間の電圧
をVaとし、既述した接触電位差をVαとすると
き、可変抵抗VRの摺動子に次式で示すような電
圧値が現われるように、摺動子の位置を調節すれ
ば、演算増幅器OAの出力端子Ｏには接触電位差
に基づくノイズ成分を含まない出力が得られる。 Now, when the voltage between the slider of the variable resistor VR and the ground is Va, and the contact potential difference mentioned above is Vα, a voltage value as shown in the following equation appears on the slider of the variable resistor VR. In addition, by adjusting the position of the slider, an output that does not contain noise components based on the contact potential difference can be obtained at the output terminal O of the operational amplifier OA.
VaR2／R1＝Vα ……(1)
なお、接触電位差Vαは通常｜0.1〜0.8｜ボルト
程度であり、可変抵抗器VRの摺動子の摺動によ
つて、上記の(1)式を満足しうる電圧値Vaは、そ
れを容易に得ることができる。 VaR 2 /R 1 = Vα ... (1) Note that the contact potential difference Vα is usually about |0.1 to 0.8 | volts, and due to the sliding of the slider of the variable resistor VR, the above equation (1) A voltage value Va that satisfies can be easily obtained.
図示の構成例のものにおいては、演算増幅器
OAの反転入力端子と出力端子Ｏとの間に、抵抗
R2とコンデンサC1との並列接続回路が接続され
ていて、コンデンサC1によつて交流信号成分に
ついてはノイズ減少回路の存在が影響を与えるこ
とがないようになされている。 In the configuration example shown, the operational amplifier
A resistor is connected between the inverting input terminal of OA and the output terminal O.
A parallel connection circuit of R 2 and capacitor C 1 is connected, and capacitor C 1 prevents the presence of the noise reduction circuit from affecting the AC signal component.
しかし、前記したコンデンサC1は、本発明の
ノイズ減少回路におけるノイズ減少の動作原理に
対しては無関係なものであるから、本発明の実施
に当つてはコンデンサC1が省略されてもよい。 However, since the capacitor C 1 described above is irrelevant to the operating principle of noise reduction in the noise reduction circuit of the present invention, the capacitor C 1 may be omitted when implementing the present invention.
上記のように構成された本発明のノイズ減少回
路は極めて簡単な構成にも拘わらず、可変電圧源
VRの電圧値を可変調節することにより、接触電
位差等に基づいて信号中に生じるノイズ成分を極
めて容易に減少させることができるのであり、し
かも本発明回路を設けても検知電極から演算増幅
器OAの入力側を見たインピーダンスを少しも低
下させることがないから、高感度の非接触型電位
計を容易に得ることができるのである。 Although the noise reduction circuit of the present invention configured as described above has an extremely simple configuration, it
By variably adjusting the voltage value of VR, it is possible to extremely easily reduce the noise component generated in the signal based on the contact potential difference, and even with the circuit of the present invention, it is possible to reduce the noise component generated in the signal from the sensing electrode to the operational amplifier OA. Since the impedance seen at the input side is not reduced at all, a highly sensitive non-contact electrometer can be easily obtained.
次に、前記したような構成の本発明のノイズ減
少回路を設けても、非接触型電位計が高い安定度
を有するものとして容易に構成できるということ
は、図示の回路配置の発振しない条件が次の(2)式
によつて示されることからも容易に理解できる。 Next, even if the noise reduction circuit of the present invention having the above-mentioned configuration is provided, the non-contact electrometer can be easily constructed as having high stability, which means that the condition that the circuit arrangement shown in the figure does not oscillate is satisfied. This can be easily understood from the following expression (2).
R4／R4＋１／｜jωC2｜×（１＋R2１／｜jωC1｜／R1
＋VRa）＜１
………(2)
（ただし、VRaは摺動子からみた可変抵抗器VR
の抵抗、ωは変同手段における変調波の角周波数
である。また、厳密には浮遊容量の存在や、位相
変化をも考慮しなければならないが、信号周波数
が数百Hzというように低く、かつ、R4≫
１／｜jωC2｜となつているので入力信号と正帰還信
号とが同位相とみなし、また、交流的なループ利
得が１以下であればよいとした。）
図中の破線内の回路による入力インピーダンス
Zinは、演算増幅器OAの固有入力インピーダン
スをZi、抵抗R2とコンデンサC1によるインピー
ダンスをZf、可変抵抗器VRと抵抗R1によるイン
ピーダンスをZr、演算増幅器OAの裸利得をAo
とすると、
Zin≒Ao（ω）Zi／１＋Zf／Zr……(3)
上記の(3)式で示される。R 4 /R 4 +1/｜jωC 2 ｜×(1+R 2 1/｜jωC 1 ｜/R 1
+VRa)＜1
………(2) (However, VRa is the variable resistor VR seen from the slider.
resistance, ω is the angular frequency of the modulating wave in the modulation means. Strictly speaking, the presence of stray capacitance and phase changes must also be taken into account, but the signal frequency is as low as several hundred Hz, and R 4 ≫
1/|jωC 2 |, so the input signal and the positive feedback signal are considered to be in the same phase, and it is sufficient that the AC loop gain is 1 or less. ) Input impedance due to the circuit within the dashed line in the figure
Zin is the specific input impedance of the operational amplifier OA, Zf is the impedance due to the resistor R 2 and the capacitor C 1 , Zr is the impedance due to the variable resistor VR and the resistor R 1 , and Ao is the bare gain of the operational amplifier OA.
Then, Zin≒Ao(ω)Zi/1+Zf/Zr...(3) It is expressed by the above equation (3).
ここで、Zf／Zr≪１なので、Zf／Zrは入力インピー
ダンスZinには殆んど影響しない。なお、抵抗
R3、R4とコンデンサC2による入力インピーダン
スZin′は、
Zin′≒R3＋R4＋R3・R4／１／jωC2である。 Here, since Zf/Zr<<1, Zf/Zr has almost no effect on the input impedance Zin. In addition, resistance
The input impedance Zin' due to R 3 , R 4 and the capacitor C 2 is Zin'≒R 3 +R 4 +R 3 ·R 4 /1/jωC 2 .
以上のとおりであつて、本発明の非接触型電位
計におけるノイズ減少回路は、非反転の増幅器と
して用いられている演算増幅器によつて構成され
ている電流電圧変換器の反転入力端子と出力端子
との間に抵抗、または抵抗とコンデンサとの並列
接続回路を接続し、また、前記の反転入力端子を
抵抗を介して可変電圧源に接続するという極めて
簡単な構成により、既述した従来の非接触型電位
計における諸問題点を良好に解消し、接触電位差
に基づいて信号中に生じるノイズ成分を可変電圧
源の電圧を調整することにより簡単に充分に減少
させることができると共に、ノイズ減少回路を設
けたことによつても非接触型電位計の感度を低下
させることがないなどの利点が得られる。 As described above, the noise reduction circuit in the non-contact electrometer of the present invention has an inverting input terminal and an output terminal of a current-voltage converter constituted by an operational amplifier used as a non-inverting amplifier. With an extremely simple configuration of connecting a resistor or a parallel connection circuit of a resistor and a capacitor between the The various problems in contact type electrometers can be satisfactorily resolved, and the noise component generated in the signal based on the contact potential difference can be easily and sufficiently reduced by adjusting the voltage of the variable voltage source, and the noise reduction circuit Even with the provision of the electrometer, there is an advantage that the sensitivity of the non-contact electrometer is not reduced.
添付図面は本発明のノイズ減少回路を含む非接
触型電位計の要部の回路図である。
Ｍ……被測定物、Ｓ……シールド面、VS……
変調手段、Ｅ……検知電極、OA……演算増幅
器、Ｏ……出力端子、R1〜R4……抵抗、C1，C2
……コンデンサ、VR……可変抵抗器。
The accompanying drawing is a circuit diagram of the main parts of a non-contact electrometer including the noise reduction circuit of the present invention. M...Object to be measured, S...Shield surface, VS...
Modulation means, E...detection electrode, OA...operational amplifier, O...output terminal, R1 to R4 ...resistance, C1 , C2
... Capacitor, VR ... Variable resistor.
Claims (1)
幅器によつて構成されている電流電圧変換器を有
する非接触型電位計において、前記した演算増幅
器の反転入力端子と出力端子との間に抵抗、また
は抵抗とコンデンサとの並列接続回路を接続し、
また、前記の演算増幅器の反転入力端子を抵抗を
介して可変電圧源に接続してなる非接触型電位計
におけるノイズ減少回路。1. In a non-contact electrometer having a current-voltage converter configured with an operational amplifier used as a non-inverting amplifier, there is a resistor between the inverting input terminal and the output terminal of the operational amplifier, or Connect a parallel connection circuit with a resistor and a capacitor,
Further, a noise reduction circuit in a non-contact electrometer is provided, in which the inverting input terminal of the operational amplifier is connected to a variable voltage source via a resistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3137879A JPS55146052A (en) | 1979-03-18 | 1979-03-18 | Noise reduction circuit in noncontact type potentiometer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3137879A JPS55146052A (en) | 1979-03-18 | 1979-03-18 | Noise reduction circuit in noncontact type potentiometer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS55146052A JPS55146052A (en) | 1980-11-14 |
| JPS6351269B2 true JPS6351269B2 (en) | 1988-10-13 |
Family
ID=12329584
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3137879A Granted JPS55146052A (en) | 1979-03-18 | 1979-03-18 | Noise reduction circuit in noncontact type potentiometer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS55146052A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55142363A (en) * | 1979-04-24 | 1980-11-06 | Canon Inc | Image forming device |
-
1979
- 1979-03-18 JP JP3137879A patent/JPS55146052A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS55146052A (en) | 1980-11-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4149231A (en) | Capacitance-to-voltage transformation circuit | |
| US6031430A (en) | Temperature stabilized oscillator and proximity switch containing the oscillator | |
| US8525529B2 (en) | Impedance detection circuit and adjustment method of impedance detection circuit | |
| US5172065A (en) | Evaluation circuit for a capacitive sensor | |
| JPH11190751A (en) | Circuit apparatus detecting capacitance or capacitance change | |
| JP3501398B2 (en) | Impedance detection circuit and impedance detection method | |
| JPS5921509B2 (en) | Electrostatic meter | |
| EP0316914A2 (en) | High-frequency oscillation type proximity switch | |
| JPS6351269B2 (en) | ||
| JP3454426B2 (en) | Impedance detection circuit and impedance detection method | |
| US5488301A (en) | Electrostatic voltmeter employing a differential cascode | |
| CA1196382A (en) | Current sensing circuit for motor controls | |
| JPH0633424Y2 (en) | Input circuit of measuring instrument | |
| JP3265807B2 (en) | Capacitive sensor | |
| JP2002044788A (en) | Microphone device | |
| JP2597861Y2 (en) | Ion concentration measurement device | |
| SU1201686A1 (en) | Capacitance level meter | |
| RU2024885C1 (en) | Device for measuring conductance | |
| JPH1031032A (en) | Signal processor for variable electrostatic capacity type acceleration sensor | |
| JPH05231890A (en) | Capacity type electromagnetic flowmeter | |
| JPH0650045Y2 (en) | DC AC addition circuit | |
| JPS5819966B2 (en) | displacement converter | |
| JPH035899Y2 (en) | ||
| JPH063463B2 (en) | Electricity detector for signal source | |
| JPS5830178Y2 (en) | capacitive displacement transducer |