JP2016080605A - Minute force and minute mass measurement device using cross capacitor - Google Patents

Minute force and minute mass measurement device using cross capacitor Download PDF

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JP2016080605A
JP2016080605A JP2014214167A JP2014214167A JP2016080605A JP 2016080605 A JP2016080605 A JP 2016080605A JP 2014214167 A JP2014214167 A JP 2014214167A JP 2014214167 A JP2014214167 A JP 2014214167A JP 2016080605 A JP2016080605 A JP 2016080605A
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JP6404080B2 (en
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藤井　賢一
Kenichi Fujii
賢一 藤井
昌史 小森
Masashi Komori
昌史 小森
和永 上田
Kazunaga Ueda
和永 上田
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National Institute of Advanced Industrial Science and Technology AIST
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Abstract

PROBLEM TO BE SOLVED: To provide a force or mass measurement device that does not require calibrating the change rate dC/dz of electrostatic capacitance.SOLUTION: Provided is a mass measurement device comprising: a cross capacitor consisting of four vertically disposed electrodes, a DC power supply for applying a voltage U to two sets of opposing electrodes, a movable guard electrode supported by a balance mechanism so as to be able to move in only the vertical direction and having the weight of a tare object canceled, with its top inserted into the cross capacitor, a measurement unit for measuring the position of the movable guard electrode, and a control device for controlling the voltage U. The control device makes an electrostatic force generated by the voltage U and a load mg balanced with each other by controlling the applied voltage U so that the value of a measurement signal of the position measurement device does not change before and after the load mg is imposed on the movable guard electrode, and calculates a mass m by an equation mg=(εln2)×(1/π)×U(m is mass, g is gravitational acceleration) where εrepresents dielectric constant between the opposing electrodes.SELECTED DRAWING: Figure 2

Description

本発明は、クロスキャパシタを用いて微小力を発生させる方法、およびその微小力と重力加速度の値から微小な質量を計測する方法に関し、また、当該方法を用いた測定装置に関する。   The present invention relates to a method for generating a minute force using a cross capacitor, a method for measuring a minute mass from the value of the minute force and gravitational acceleration, and a measuring apparatus using the method.

分銅による校正を必要としない微小力、微小質量の標準としては、静電容量Ｃのキャパシタの極板間に働く静電力を用いた、電圧天びん装置が知られている。これは、キャパシタに印加した電圧Ｕおよび、キャパシタの形状変化による静電容量の変化率ｄＣ／ｄｚから、発生する静電力の大きさを算出し、荷重とつり合わせるものである。従来、この装置に使われるキャパシタは、図４に示す同軸二重円筒形が主流であった。この時に発生する力Ｆは以下のとおりである（非特許文献１、２参照）。
ｍｇ＝Ｆ＝(１／２)・(ｄＣ／ｄｚ)・Ｕ2
ここで、ｍは質量、ｇは重力加速度である。なお、図中のバランス機構は内筒部分をｚ方向（鉛直方向）にのみ移動可能に支持するとともに風袋物の重量を相殺する機構を備えている。 As a standard of minute force and minute mass that does not require calibration with a weight, a voltage balance apparatus using an electrostatic force acting between the plates of a capacitor having a capacitance C is known. This calculates the magnitude of the generated electrostatic force from the voltage U applied to the capacitor and the capacitance change rate dC / dz due to the change in the shape of the capacitor, and balances it with the load. Conventionally, the capacitor used in this device has been mainly the coaxial double cylinder shown in FIG. The force F generated at this time is as follows (see Non-Patent Documents 1 and 2).
mg = F = (1/2) · (dC / dz) · U 2
Here, m is mass and g is gravitational acceleration. The balance mechanism in the figure includes a mechanism that supports the inner cylinder portion so as to be movable only in the z direction (vertical direction) and cancels the weight of the tare.

J.R.Pratt, J.A.Kramar, D.B.Newell, D.T.Smith,「Review of SI traceable force metrology for instrumented indentation and atomic force microscopy」, Meas. Sci. Technol. 16 (2005) 2129-2137J.R.Pratt, J.A.Kramar, D.B.Newell, D.T.Smith, `` Review of SI traceable force metrology for instrumented indentation and atomic force microscopy '', Meas. Sci. Technol. 16 (2005) 2129-2137 GANG HU,et al 「RESEARCH AND DEVELOPMENT OF SMALL FORCE STANDARDS AT NIM」,Int. J. Mod. Phys. Conf. Sert. 24, 1360020 (2013)GANG HU, et al “RESEARCH AND DEVELOPMENT OF SMALL FORCE STANDARDS AT NIM”, Int. J. Mod. Phys. Conf. Sert. 24, 1360020 (2013) A.M.Thompson, D.G.Lampard,「A new theorem in electrostatics and its application to calculable standards and capacitance」, Nature,177, p. 888(1956)A.M.Thompson, D.G.Lampard, `` A new theorem in electrostatics and its application to calculable standards and capacitance '', Nature, 177, p. 888 (1956) 中村安弘、堂前篤志「ものづくり産業の国際競争を支援する電気標準−キャパシタンス標準の実現と計量トレーサビリティの確率−」,Synthesiology Vol.3 No.3 pp213-222(Aug.2010)Yasuhiro Nakamura, Atsushi Dozen “Electrical Standards Supporting International Competition in the Manufacturing Industry: Realization of Capacitance Standards and Probability of Metrological Traceability”, Synthesiology Vol.3 No.3 pp213-222 (Aug.2010)

上記従来の図４に示した同軸二重円筒形の測定装置では、同軸二重円筒形の電極の一方を力の発生方向に移動させて、その時の移動距離ｚと静電容量を測定する作業を繰り返して、静電容量の変化率ｄＣ／ｄｚを校正することが必要となる。この静電容量の変化率の測定は、発生する力の大きさの不確かさの主要因になっていた。また、この手法で１[ｎＮ]を下回る微小な力を発生する場合には、１[Ｖ]以下の電圧が必要であり、この領域では印加電圧の不確かさが大きくなってしまうため、１[ｎＮ]を下回る微小力の発生、あるいは、０.１[μｇ]を下回る微小質量の測定には適していない。またシステムには、レーザー干渉計などによる移動距離測定装置と静電容量測定装置が必要であるため、装置の小型化を図る上でのボトルネックとなっていた。
したがって、本発明の解決しようとする課題は、静電容量の変化率ｄＣ／ｄｚを校正することを必要としない微小力および微小質量の測定装置を提供することにある。 In the conventional coaxial double cylindrical measuring apparatus shown in FIG. 4, the operation of moving one of the coaxial double cylindrical electrodes in the force generation direction and measuring the moving distance z and the capacitance at that time is performed. It is necessary to calibrate the capacitance change rate dC / dz by repeating the above. This measurement of the rate of change in capacitance has been a major factor in the uncertainty of the magnitude of the force generated. In addition, when a minute force lower than 1 [nN] is generated by this method, a voltage of 1 [V] or less is necessary, and in this region, the uncertainty of the applied voltage becomes large. It is not suitable for the generation of microforces below nN] or the measurement of micromass below 0.1 [μg]. In addition, since the system requires a moving distance measuring device such as a laser interferometer and a capacitance measuring device, it has become a bottleneck in reducing the size of the device.
Therefore, the problem to be solved by the present invention is to provide a measurement apparatus for minute force and minute mass that does not require calibration of the capacitance change rate dC / dz.

これに対して、本願発明者はクロスキャパシタによって、微小な力を発生させることが可能であること、またその際に静電容量の変化率ｄＣ／ｄｚの校正が不要になることを利用して新たな微小力および微小質量の測定装置を開発した。
図１に示す互いに平行に配置された４本の電極からなるクロスキャパシタでは、対向する電極に電圧をかけた時、蓄えられた静電エネルギーを減少させるように、ガード電極が深く挿入される方向に力が働く（図１の可動ガード電極が深く挿入される方向（鉛直上方向）に力が働き、力の大きさはクロスキャパシタの静電容量の移動方向の変位による変化率ｄＣ／ｄｚによって求められる）。その時の力を求めるために必要な静電容量の変化率ｄＣ／ｄｚは、対向する２組の電極同士の単位長さあたりの静電容量の和に等しい。図１の上面図のように電極１、２、３、４を配置したクロスキャパシタの、対向する電極の単位長さあたりの静電容量の合計をＣ13＋Ｃ24とすると、その値は理論計算によって以下のように求めることができ（非特許文献３、４参照）、一定の値となる。
Ｃ13＋Ｃ24＝(２ε0ｌｎ２)／π＝３.９０７０９８０９[ｐＦ／ｍ]
ここで、ε0は電極間の誘電率であり、ｌｎは自然対数を表す記号で有り、全体を真空中においた場合には上式の最右辺の値となる。したがって、この値（理論計算で求まる一定の値）をそのまま校正不要な静電容量の変化率ｄＣ／ｄｚとして用いることができる。 On the other hand, the inventor of the present application utilizes the fact that it is possible to generate a minute force with a cross capacitor, and that calibration of the capacitance change rate dC / dz is not required at that time. A new measuring device for micro force and mass was developed.
In the cross capacitor consisting of four electrodes arranged in parallel to each other shown in FIG. 1, the direction in which the guard electrode is inserted deeply so as to reduce the stored electrostatic energy when a voltage is applied to the opposing electrodes. (The force acts in the direction in which the movable guard electrode in FIG. 1 is inserted deeply (vertically upward), and the magnitude of the force depends on the rate of change dC / dz due to the displacement of the capacitance of the cross capacitor in the moving direction. Desired). The change rate dC / dz of the capacitance necessary for obtaining the force at that time is equal to the sum of the capacitances per unit length between the two pairs of electrodes facing each other. Assuming that the total capacitance per unit length of the opposing electrodes of the cross capacitor in which the electrodes 1, 2, 3, 4 are arranged as shown in the top view of FIG. 1 is C 13 + C 24 , the value is calculated theoretically. Can be obtained as follows (see Non-Patent Documents 3 and 4), and becomes a constant value.
C 13 + C 24 = (2ε 0 ln2) /π=3.970909809 [pF / m]
Here, ε 0 is the dielectric constant between the electrodes, ln is a symbol representing the natural logarithm, and is the rightmost value of the above equation when the whole is placed in a vacuum. Therefore, this value (a constant value obtained by theoretical calculation) can be used as it is as the capacitance change rate dC / dz that does not require calibration.

そこで、本発明は、鉛直に配置した４本の電極からなるクロスキャパシタと、前記クロスキャパシタの対向する電極２組に電圧Ｕを印加する直流電源と、バランス機構により鉛直方向にのみ移動可能に支持されかつ風袋物の重量を相殺されるとともにその上部が前記クロスキャパシタ内に挿入されている可動ガード電極と、前記可動ガード電極の鉛直方向の位置の変化を測定する位置測定器と、前記電圧Ｕを制御する制御装置を備え、前記制御装置は、前記位置測定器の測定信号の値が前記可動ガード電極に力Ｌまたは荷重ｍｇを掛ける前と後で値が変化しないように前記電圧Ｕを制御することにより、前記電圧Ｕで発生する静電力と前記力Ｌまたは荷重ｍｇを釣り合わせ、ε0を前記対向する電極間の誘電率としたとき、次式
Ｌ＝(ε0ｌｎ２)・(１／π)・Ｕ2
または、次式
ｍｇ＝(ε0ｌｎ２)・(１／π)・Ｕ2（ここで、ｍは質量、ｇは重力加速度）
により力Ｌまたは質量ｍを算出することを特徴とする力測定装置または質量測定装置である。
また、本発明は、鉛直に配置した４本の電極からなるクロスキャパシタと、前記クロスキャパシタの対向する電極２組に電圧Ｕを印加する直流電源と、バランス機構により鉛直方向にのみ移動可能に支持されかつ風袋物の重量を相殺されるとともにその上部が前記クロスキャパシタ内に挿入されている可動ガード電極と、前記対向する電極間のキャパシタンスの変化を測定するキャパシタンス測定器と、前記電圧Ｕを制御する制御装置を備え、前記制御装置は、前記キャパシタンス測定器の測定信号の値が前記ガード電極に力Ｌまたは荷重ｍｇを掛ける前後の値が変化しないように前記電圧Ｕを制御することにより、前記電圧Ｕで発生する静電力と前記力Ｌまたは荷重ｍｇを釣り合わせ、ε0を前記対向する電極間の誘電率としたとき、次式
Ｌ＝(ε0ｌｎ２)・(１／π)・Ｕ2
または、次式
ｍｇ＝(ε0ｌｎ２)・(１／π)・Ｕ2（ここで、ｍは質量、ｇは重力加速度）
により力Ｌまたは質量ｍを算出することを特徴とする力測定装置または質量測定装置である。
また、本発明は、鉛直に配置した４本の電極からなるクロスキャパシタと、バランス機構により鉛直方向にのみ移動可能に支持されかつ風袋物の重量を相殺された可動ガード電極であってその上部が前記クロスキャパシタ内に挿入されている可動ガード電極と、前記可動ガード電極の鉛直方向の位置の変化を測定する位置測定器と、クロスキャパシタの対向する電極２組に印加する電圧Ｕを制御する制御装置を用い、前記位置測定器の測定信号の値が前記可動ガード電極に力Ｌまたは荷重ｍｇを掛ける前と後で変化しないように前記電圧Ｕを制御することにより、前記電圧Ｕで発生する静電力と前記力Ｌまたは荷重ｍｇを釣り合わせ、ε0を前記対向する電極間の誘電率としたとき、次式
Ｌ＝(ε0ｌｎ２)・(１／π)・Ｕ2
または、次式
ｍｇ＝(ε0ｌｎ２)・(１／π)・Ｕ2
ここで、ｍは質量、ｇは重力加速度により力Ｌまたは質量ｍを算出することを特徴とする力測定方法または質量測定方法。
また、本発明は、鉛直に配置した４本の電極からなるクロスキャパシタと、バランス機構により鉛直方向にのみ移動可能に支持されかつ風袋物の重量を相殺された可動ガード電極であってその上部が前記クロスキャパシタ内に挿入されている可動ガード電極と、前記対向する電極間のキャパシタンスの変化を測定するキャパシタンス測定器と、クロスキャパシタの対向する電極２組に印加する電圧Ｕを制御する制御装置を用い、前記キャパシタンス測定器の測定信号の値が前記可動ガード電極に力Ｌまたは荷重ｍｇを掛ける前と後で変化しないように前記電圧Ｕを制御することにより、前記電圧Ｕで発生する静電力と前記力Ｌまたは荷重ｍｇを釣り合わせ、ε0を前記対向する電極間の誘電率としたとき、次式
Ｌ＝(ε0ｌｎ２)・(１／π)・Ｕ2
または、次式
ｍｇ＝(ε0ｌｎ２)・(１／π)・Ｕ2
ここで、ｍは質量、ｇは重力加速度により力Ｌまたは質量ｍを算出することを特徴とする力測定方法または質量測定方法。 Therefore, the present invention supports a cross capacitor composed of four electrodes arranged vertically, a direct current power source that applies a voltage U to two sets of electrodes facing the cross capacitor, and a balance mechanism that is movable only in the vertical direction. A movable guard electrode whose upper part is inserted in the cross capacitor, a position measuring device for measuring a change in the vertical position of the movable guard electrode, and the voltage U The control device controls the voltage U so that the value of the measurement signal of the position measuring device does not change before and after the force L or the load mg is applied to the movable guard electrode. by, when the voltage mated the force L or load mg and electrostatic force generated by the U, the epsilon 0 and the dielectric constant between the facing electrodes, the following equation L = (epsilon 0 ln ) · (1 / π) · U 2
Or the following formula mg = (ε 0 ln2) · (1 / π) · U 2 (where m is mass and g is gravitational acceleration)
The force measuring device or the mass measuring device is characterized in that the force L or the mass m is calculated by the above.
Further, the present invention supports a cross capacitor composed of four electrodes arranged vertically, a direct current power source that applies a voltage U to two sets of electrodes facing the cross capacitor, and a balance mechanism that is movable only in the vertical direction. And the weight of the tare is offset and the upper part of the movable guard electrode inserted in the cross capacitor, the capacitance measuring device for measuring the change in capacitance between the opposing electrodes, and the voltage U are controlled. The control device controls the voltage U so that the value of the measurement signal of the capacitance measuring device does not change before and after the guard electrode is applied with a force L or a load mg. mated the force L or load mg and electrostatic force generated by a voltage U, when the epsilon 0 and the dielectric constant between the facing electrodes, the following equation = (Ε 0 ln2) · ( 1 / π) · U 2
Or the following formula mg = (ε 0 ln2) · (1 / π) · U 2 (where m is mass and g is gravitational acceleration)
The force measuring device or the mass measuring device is characterized in that the force L or the mass m is calculated by the above.
Further, the present invention is a cross-capacitor composed of four electrodes arranged vertically, and a movable guard electrode which is supported so as to be movable only in the vertical direction by a balance mechanism and whose weight of the tare is offset. A movable guard electrode inserted in the cross capacitor, a position measuring device for measuring a change in the vertical position of the movable guard electrode, and a control for controlling a voltage U applied to two sets of opposing electrodes of the cross capacitor. By using the device, the voltage U is controlled so that the value of the measurement signal of the position measuring device does not change before and after the force L or the load mg is applied to the movable guard electrode. When the power and the force L or the load mg are balanced and ε 0 is the dielectric constant between the opposing electrodes, the following equation is obtained: L = (ε 0 ln2) · (1 / π) · U 2
Or, the following formula mg = (ε 0 ln2) · (1 / π) · U 2
Here, m is a mass, g is a force measuring method or a mass measuring method, wherein force L or mass m is calculated by gravitational acceleration.
Further, the present invention is a cross-capacitor composed of four electrodes arranged vertically, and a movable guard electrode which is supported so as to be movable only in the vertical direction by a balance mechanism and whose weight of the tare is offset. A movable guard electrode inserted in the cross capacitor; a capacitance measuring device for measuring a change in capacitance between the opposing electrodes; and a control device for controlling a voltage U applied to two sets of opposing electrodes of the cross capacitor. The electrostatic force generated at the voltage U by controlling the voltage U so that the value of the measurement signal of the capacitance measuring device does not change before and after the force L or the load mg is applied to the movable guard electrode. When the force L or the load mg is balanced and ε 0 is the dielectric constant between the opposing electrodes, the following equation is obtained: L = (ε 0 ln2) · (1 / π) · U 2
Or, the following formula mg = (ε 0 ln2) · (1 / π) · U 2
Here, m is a mass, g is a force measuring method or a mass measuring method, wherein force L or mass m is calculated by gravitational acceleration.

本発明では、静電容量の変化率ｄＣ／ｄｚが理論計算により求まる一定の値となるので、従来の同軸二重円筒形法で必須だったｄＣ／ｄｚの校正が不必要となり、ｄＣ／ｄｚを測定する際の相対標準不確かさであった１０-4〜１０-3を３桁以上改善することができる。
また、本発明では、従来法に比べてｄＣ／ｄｚの値を２〜３桁小さくすることができる。このことによって、同電圧で発生する力も２〜３桁小さくなるため、特に１[ｎＮ]を下回るような微小な力を、より高精度に測定することができる。
加えて、従来法ではレーザー干渉計などによる移動距離測定装置と静電容量測定装置が必要であったが、本発明によっていずれか片方のみでシステムを構成することが可能になり、装置の小型化、低コスト化に貢献する。 In the present invention, since the capacitance change rate dC / dz is a constant value obtained by theoretical calculation, calibration of dC / dz, which is essential in the conventional coaxial double cylinder method, is unnecessary, and dC / dz. It is possible to improve 10 −4 to 10 −3 , which was a relative standard uncertainty when measuring, by 3 digits or more.
In the present invention, the value of dC / dz can be reduced by 2 to 3 orders of magnitude compared with the conventional method. As a result, the force generated at the same voltage is also reduced by two to three orders of magnitude, so that a minute force particularly lower than 1 [nN] can be measured with higher accuracy.
In addition, the conventional method required a moving distance measuring device such as a laser interferometer and a capacitance measuring device, but the present invention makes it possible to configure a system with only one of them, and downsizing the device. Contributes to cost reduction.

図１は、クロスキャパシタを説明するための全体斜視図と上面図であり、全体斜視図において、互いに平行に配置された４本の電極とその中央に配置された固定ガード電極および可動ガード電極が示されており、両ガード電極の配置をわかりやすくするために手前の１本の電極の一部を破断して示した図である。また、上面図は、４本の電極１、２、３、４のうち対向する電極の単位長さあたりの静電容量Ｃ13、Ｃ24を説明した図である。FIG. 1 is an overall perspective view and a top view for explaining a cross capacitor. In the overall perspective view, four electrodes arranged in parallel with each other, and a fixed guard electrode and a movable guard electrode arranged in the center thereof are shown. It is shown, and in order to make it easy to understand the arrangement of both guard electrodes, it is a diagram showing a part of one front electrode broken away. Further, the top view is a diagram illustrating the capacitances C 13 and C 24 per unit length of the opposing electrodes among the four electrodes 1, 2, 3, and 4. 図２は、本発明の実施例１の上面図と側面図を示したものである。FIG. 2 shows a top view and a side view of the first embodiment of the present invention. 図３は、本発明の実施例２の上面図と側面図を示したものである。FIG. 3 shows a top view and a side view of the second embodiment of the present invention. 図４は、従来の同軸二重円筒形の測定装置を示した図である。FIG. 4 is a diagram showing a conventional coaxial double cylindrical measuring device.

（実施例１）
図２は本発明の一実施例である実施例１の上面図と側面図である。図２において、ａは互いに平行な４本の直円柱の電極１〜４を対向させたクロスキャパシタである。電極１と３の間の静電容量をＣ13、電極２と４の間の静電容量をＣ24とする。このとき対向する２電極間の単位長さあたりの静電容量の和は
Ｃ13＋Ｃ24＝(２ε0ｌｎ２)／π＝３.９０７０９８０９[ｐＦ／ｍ]
である。ｂは固定ガード電極、ｃは可動ガード電極であり、可動ガード電極ｃはバランス機構ｅによって鉛直方向にのみ移動可能であり、バランス機構ｅは図示しない風袋物の重量を相殺する機構を有している。可動ガード電極ｃの鉛直方向の動きはレーザー測長器ｆによって観測されている。また、図中のハッチング部分は固定されている部分を示すためのものである。ここで荷重皿ｄに荷重Ｌ（力）をかけた時、可動ガード電極ｃを、荷重Ｌ（力）をかける前と同じ位置に保つように直流電源ｇによって電圧Ｕをクロスキャパシタａに印加する。この時、静電力により、可動ガード電極ｃには上向きの力Ｆが発生し、荷重Ｌ（力）と釣り合う。釣り合った時の荷重Ｌ（力）は、印加電圧をＵとした時、以下のように表すことができる。
Ｌ＝Ｆ＝(ε0ｌｎ２)・(１／π)・Ｕ2
また、この時の力Ｌが質量ｍの分銅に働く重力ｍｇである場合、
ｍｇ＝Ｆ＝(ε0ｌｎ２)・(１／π)・Ｕ2
と表され、重力加速度ｇから質量ｍを求めることも可能である。
すなわち、実施例１の装置は、力Ｌの測定装置としても、質量ｍの測定装置としても用いることができる。
なお、レーザー測長器ｆは可動ガードｃの鉛直方向の位置の変化を非接触で測定できる位置測定器であればよく、レーザー測長器に限定されるものではない。 Example 1
FIG. 2 is a top view and a side view of the first embodiment which is an embodiment of the present invention. In FIG. 2, a is a cross capacitor in which four parallel cylindrical electrodes 1 to 4 are opposed to each other. The capacitance between the electrodes 1 and 3 is C 13 , and the capacitance between the electrodes 2 and 4 is C 24 . At this time, the sum of the capacitance per unit length between the two electrodes facing each other is C 13 + C 24 = (2ε 0 ln2) /π=3.9709709809 [pF / m]
It is. b is a fixed guard electrode, c is a movable guard electrode, the movable guard electrode c is movable only in the vertical direction by a balance mechanism e, and the balance mechanism e has a mechanism for canceling the weight of the tare (not shown). Yes. The movement of the movable guard electrode c in the vertical direction is observed by the laser length measuring device f. Moreover, the hatching part in a figure is for showing the part currently fixed. Here, when a load L (force) is applied to the load pan d, a voltage U is applied to the cross capacitor a by the DC power source g so as to keep the movable guard electrode c at the same position as before applying the load L (force). . At this time, due to the electrostatic force, an upward force F is generated in the movable guard electrode c, which is balanced with the load L (force). The load L (force) when balanced can be expressed as follows when the applied voltage is U.
L = F = (ε 0 ln2) · (1 / π) · U 2
In addition, when the force L at this time is gravity mg acting on a weight of mass m,
mg = F = (ε 0 ln2) · (1 / π) · U 2
It is also possible to obtain the mass m from the gravitational acceleration g.
That is, the apparatus of Example 1 can be used as a measuring apparatus for the force L or a measuring apparatus for mass m.
The laser length measuring device f may be any position measuring device that can measure the change in the vertical position of the movable guard c in a non-contact manner, and is not limited to the laser length measuring device.

（実施例２）
図３は本発明の他の実施例である実施例２の上面図と側面図である。図３の実施例２においては、図２（実施例１）のレーザー測長器ｆの代わりに、キャパシタンス測定器ｈを組み込んでいる点が異なる。実施例１において、可動ガード電極ｃの位置はレーザー測長器によって観測を行っていたが、本実施例２ではキャパシタンス測定器ｈによって観測を行う。クロスキャパシタは単位長さあたりの静電容量が既知（一定の値）であるため、固定及び可動ガード電極でガードされていない部分の全長さからなる静電容量の変化を観測することによって、間接的に変位も測定することができる。荷重をかけた時に、対向する２組の電極対の静電容量の合計が変化しないように、印加電圧Ｕを制御することによって、可動ガード電極の位置を常に一定に保つことができる。その他の原理、測定の手順は実施例１と同様である。 (Example 2)
FIG. 3 is a top view and a side view of a second embodiment which is another embodiment of the present invention. The second embodiment of FIG. 3 is different in that a capacitance measuring device h is incorporated in place of the laser length measuring device f of FIG. 2 (first embodiment). In the first embodiment, the position of the movable guard electrode c is observed by the laser length measuring device, but in the second embodiment, the position is observed by the capacitance measuring device h. Since the capacitance per unit length of the cross capacitor is known (a constant value), indirect by observing the change in capacitance consisting of the total length of the part that is not guarded by the fixed and movable guard electrodes In addition, the displacement can be measured. By controlling the applied voltage U so that the total capacitance of the two opposing electrode pairs does not change when a load is applied, the position of the movable guard electrode can always be kept constant. Other principles and measurement procedures are the same as in the first embodiment.

本発明は力の測定や、質量の測定に利用でき、しかも従来の二重円筒形静電容量方式で必要としていたｄＣ／ｄｚの校正を必要とせず、微小力の測定や微小質量の測定が可能となる。   The present invention can be used for force measurement and mass measurement, and does not require the dC / dz calibration required in the conventional double-cylindrical capacitance method. It becomes possible.

ａ クロスキャパシタを校正する４つの電極（１〜４）
ｂ 固定ガード電極
ｃ 可動ガード電極
ｄ 荷重皿
ｅ バランス機構
ｆ レーザー測長器
ｇ 直流電源
ｈ キャパシタンス測定器 a Four electrodes (1 to 4) for calibrating the cross capacitor
b Fixed guard electrode c Movable guard electrode d Load pan e Balance mechanism f Laser length measuring g DC power source h Capacitance measuring device

Claims (4)

鉛直に配置した４本の電極からなるクロスキャパシタと、前記クロスキャパシタの対向する電極２組に電圧Ｕを印加する直流電源と、バランス機構により鉛直方向にのみ移動可能に支持されかつ風袋物の重量を相殺されるとともにその上部が前記クロスキャパシタ内に挿入されている可動ガード電極と、前記可動ガード電極の鉛直方向の位置の変化を測定する位置測定器と、前記電圧Ｕを制御する制御装置を備え、
前記制御装置は、前記位置測定器の測定信号の値が前記可動ガード電極に力Ｌまたは荷重ｍｇを掛ける前後の値が変化しないように前記電圧Ｕを制御することにより、前記電圧Ｕで発生する静電力と前記力Ｌまたは荷重ｍｇを釣り合わせ、ε0を前記対向する電極間の誘電率としたとき、次式
Ｌ＝(ε0ｌｎ２)・(１／π)・Ｕ2
または、次式
ｍｇ＝(ε0ｌｎ２)・(１／π)・Ｕ2
ここで、ｍは質量、ｇは重力加速度により力Ｌまたは質量ｍを算出することを特徴とする力測定装置または質量測定装置。 The weight of the tare is supported by a cross capacitor composed of four electrodes arranged vertically, a DC power source for applying a voltage U to two pairs of electrodes facing the cross capacitor, and a balance mechanism so as to be movable only in the vertical direction. A movable guard electrode whose upper portion is inserted into the cross capacitor, a position measuring device for measuring a change in the vertical position of the movable guard electrode, and a control device for controlling the voltage U. Prepared,
The control device generates the voltage U by controlling the voltage U so that the value of the measurement signal from the position measuring device does not change before and after the force L or the load mg is applied to the movable guard electrode. When the electrostatic force and the force L or the load mg are balanced and ε 0 is the dielectric constant between the opposing electrodes, the following equation is obtained: L = (ε 0 ln2) · (1 / π) · U 2
Or, the following formula mg = (ε 0 ln2) · (1 / π) · U 2
Here, m is a mass, g is a force measuring device or a mass measuring device that calculates force L or mass m by gravitational acceleration. 鉛直に配置した４本の電極からなるクロスキャパシタと、前記クロスキャパシタの対向する電極２組に電圧Ｕを印加する直流電源と、バランス機構により鉛直方向にのみ移動可能に支持されかつ風袋物の重量を相殺されるとともにその上部が前記クロスキャパシタ内に挿入されている可動ガード電極と、前記対向する電極間のキャパシタンスの変化を測定するキャパシタンス測定器と、前記電圧Ｕを制御する制御装置を備え、
前記制御装置は、前記キャパシタンス測定器の測定信号の値が前記ガード電極に力Ｌまたは荷重ｍｇを掛ける前後の値が変化しないように前記電圧Ｕを制御することにより、前記電圧Ｕで発生する静電力と前記力Ｌまたは荷重ｍｇを釣り合わせ、ε0を前記対向する電極間の誘電率としたとき、次式
Ｌ＝(ε0ｌｎ２)・(１／π)・Ｕ2
または、次式
ｍｇ＝(ε0ｌｎ２)・(１／π)・Ｕ2
ここで、ｍは質量、ｇは重力加速度により力Ｌまたは質量ｍを算出することを特徴とする力測定装置または質量測定装置。 The weight of the tare is supported by a cross capacitor composed of four electrodes arranged vertically, a DC power source for applying a voltage U to two pairs of electrodes facing the cross capacitor, and a balance mechanism so as to be movable only in the vertical direction. A movable guard electrode whose upper part is inserted into the cross capacitor, a capacitance measuring device for measuring a change in capacitance between the opposing electrodes, and a control device for controlling the voltage U,
The control device controls the voltage U so that the value of the measurement signal of the capacitance measuring device does not change before and after the force L or the load mg is applied to the guard electrode, so that the static voltage generated at the voltage U is controlled. When the power and the force L or the load mg are balanced and ε 0 is the dielectric constant between the opposing electrodes, the following equation is obtained: L = (ε 0 ln2) · (1 / π) · U 2
Or, the following formula mg = (ε 0 ln2) · (1 / π) · U 2
Here, m is a mass, g is a force measuring device or a mass measuring device that calculates force L or mass m by gravitational acceleration. 鉛直に配置した４本の電極からなるクロスキャパシタと、バランス機構により鉛直方向にのみ移動可能に支持されかつ風袋物の重量を相殺された可動ガード電極であってその上部が前記クロスキャパシタ内に挿入されている可動ガード電極と、前記可動ガード電極の鉛直方向の位置の変化を測定する位置測定器と、クロスキャパシタの対向する電極２組に印加する電圧Ｕを制御する制御装置を用い、
前記位置測定器の測定信号の値が前記可動ガード電極に力Ｌまたは荷重ｍｇを掛ける前と後で変化しないように前記電圧Ｕを制御することにより、前記電圧Ｕで発生する静電力と前記力Ｌまたは荷重ｍｇを釣り合わせ、ε0を前記対向する電極間の誘電率としたとき、次式
Ｌ＝(ε0ｌｎ２)・(１／π)・Ｕ2
または、次式
ｍｇ＝(ε0ｌｎ２)・(１／π)・Ｕ2
ここで、ｍは質量、ｇは重力加速度により力Ｌまたは質量ｍを算出することを特徴とする力測定方法または質量測定方法。 A cross capacitor composed of four electrodes arranged vertically, and a movable guard electrode that is supported so as to be movable only in the vertical direction by a balance mechanism and offset the weight of the tare, and the upper part thereof is inserted into the cross capacitor. A movable guard electrode, a position measuring device that measures a change in the vertical position of the movable guard electrode, and a control device that controls a voltage U applied to two opposing electrodes of the cross capacitor,
By controlling the voltage U so that the value of the measurement signal of the position measuring device does not change before and after the force L or the load mg is applied to the movable guard electrode, the electrostatic force and the force generated by the voltage U are controlled. When L or load mg is balanced and ε 0 is the dielectric constant between the opposing electrodes, the following equation is obtained: L = (ε 0 ln2) · (1 / π) · U 2
Or, the following formula mg = (ε 0 ln2) · (1 / π) · U 2
Here, m is a mass, g is a force measuring method or a mass measuring method, wherein force L or mass m is calculated by gravitational acceleration. 鉛直に配置した４本の電極からなるクロスキャパシタと、バランス機構により鉛直方向にのみ移動可能に支持されかつ風袋物の重量を相殺された可動ガード電極であってその上部が前記クロスキャパシタ内に挿入されている可動ガード電極と、前記対向する電極間のキャパシタンスの変化を測定するキャパシタンス測定器と、クロスキャパシタの対向する電極２組に印加する電圧Ｕを制御する制御装置を用い、
前記キャパシタンス測定器の測定信号の値が前記可動ガード電極に力Ｌまたは荷重ｍｇを掛ける前と後で変化しないように前記電圧Ｕを制御することにより、前記電圧Ｕで発生する静電力と前記力Ｌまたは荷重ｍｇを釣り合わせ、ε0を前記対向する電極間の誘電率としたとき、次式
Ｌ＝(ε0ｌｎ２)・(１／π)・Ｕ2
または、次式
ｍｇ＝(ε0ｌｎ２)・(１／π)・Ｕ2
ここで、ｍは質量、ｇは重力加速度により力Ｌまたは質量ｍを算出することを特徴とする力測定方法または質量測定方法。 A cross capacitor composed of four electrodes arranged vertically, and a movable guard electrode that is supported so as to be movable only in the vertical direction by a balance mechanism and offset the weight of the tare, and the upper part thereof is inserted into the cross capacitor. A movable guard electrode, a capacitance measuring device that measures a change in capacitance between the opposing electrodes, and a control device that controls a voltage U applied to two opposing electrodes of the cross capacitor,
By controlling the voltage U so that the value of the measurement signal of the capacitance measuring device does not change before and after the force L or the load mg is applied to the movable guard electrode, the electrostatic force and the force generated by the voltage U are controlled. When L or load mg is balanced and ε 0 is the dielectric constant between the opposing electrodes, the following equation is obtained: L = (ε 0 ln2) · (1 / π) · U 2
Or, the following formula mg = (ε 0 ln2) · (1 / π) · U 2
Here, m is a mass, g is a force measuring method or a mass measuring method, wherein force L or mass m is calculated by gravitational acceleration.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01299427A (en) * 1988-05-27 1989-12-04 Showa Electric Wire & Cable Co Ltd Zero displacement load indicator
JPH1194884A (en) * 1997-09-17 1999-04-09 Agency Of Ind Science & Technol Method for precisely measuring high voltage
JP2011133329A (en) * 2009-12-24 2011-07-07 Anritsu Sanki System Co Ltd Balance
US20130233077A1 (en) * 2012-03-08 2013-09-12 Industrial Technology Research Institute Electrostatic force generator and force measurement system and accelerometer having the same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01299427A (en) * 1988-05-27 1989-12-04 Showa Electric Wire & Cable Co Ltd Zero displacement load indicator
JPH1194884A (en) * 1997-09-17 1999-04-09 Agency Of Ind Science & Technol Method for precisely measuring high voltage
JP2011133329A (en) * 2009-12-24 2011-07-07 Anritsu Sanki System Co Ltd Balance
US20130233077A1 (en) * 2012-03-08 2013-09-12 Industrial Technology Research Institute Electrostatic force generator and force measurement system and accelerometer having the same

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