JP4130188B2 - Surface electrometer - Google Patents
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Description
本発明は、物体の表面電位を測定するための表面電位計に関する。 The present invention relates to a surface potential meter for measuring the surface potential of the object.
静電気を帯びた物体の表面電位の測定には非接触型の測定器が用いられる。この種の測定器としては、被測定面と対向する振動電極をもつ振動容量型の表面電位計が一般的である。 A non-contact type measuring device is used for measuring the surface potential of an electrostatically charged object. As this type of measuring device, a vibration capacity type surface potentiometer having a vibrating electrode facing the surface to be measured is generally used.
例えば特開2000−147036号公報に記載された電界測定形式の振動容量型の表面電位計は振動電極と固定電極とを有しており、固定電極の電位を参照することによって被測定面の微小位置変動に因る測定誤差を低減するように構成されている。 For example, a vibration capacity type surface potential meter of the electric field measurement type described in Japanese Patent Application Laid-Open No. 2000-147036 has a vibration electrode and a fixed electrode, and the surface of the surface to be measured is made minute by referring to the potential of the fixed electrode. The measurement error due to the position variation is configured to be reduced.
また、振動電極を内蔵するプローブと高電圧源を備える本体とから構成された表面電位計が市販されている。この表面電位計では、プローブの電位を徐々に上昇させて、振動電極からの変位信号が無くなった時点のプローブの電位を測定値とするゼロ位法が用いられている。
従来の表面電位計による測定は、表面電位計の設置が面倒であったり、表面電位計の装置構成が大掛かりであったりして手軽ではなかった。すなわち、上述した電界測定形式の表面電位計は多少の距離変動は許容されるものの、基本的には被測定面との対向距離が規定値となるように被測定面と表面電位計との位置決めをする必要がある。一方、ゼロ位法による測定は対向距離の依存性が小さいものの、高電圧源を備えた表面電位計は重く可搬性に劣るので、互いに離れた複数の被測定面のそれぞれについて測定する場合のように表面電位計の移動が必要な場合には好適ではない。 Measurement using a conventional surface electrometer is not easy because the installation of the surface electrometer is troublesome or the apparatus configuration of the surface electrometer is large. In other words, although the above-described surface electrometer of the electric field measurement format allows a slight distance variation, the positioning of the surface to be measured and the surface electrometer is basically such that the facing distance from the surface to be measured is a specified value. It is necessary to do. On the other hand, the measurement by the zero position method is less dependent on the facing distance, but the surface electrometer with a high voltage source is heavy and inferior in portability. It is not suitable when it is necessary to move the surface electrometer.
本発明は表面電位の手軽な測定の実現を目的としている。他の目的は小型軽量の表面電位計を提供することである。 An object of the present invention is to realize easy measurement of the surface potential. Another object is to provide a small and light surface electrometer.
本発明に係る表面電位計は、第1固定電極、第2固定電極、外部接続端子、基準電位ライン、第1コンデンサ、第2コンデンサ、電圧検出回路、演算手段、および表示器を備える。第1固定電極は被測定面と対向する。第2固定電極は、前記第1固定電極と段違いに配置され、前記第1固定電極よりも被測定面に近い位置で被測定面と対向する。基準電位ラインは外部接続端子に接続される。第1コンデンサは、その一端が前記第1固定電極に接続され、その他端が前記基準電位ラインに接続される。第2コンデンサは、その一端が前記第2固定電極に接続され、その他端が前記基準電位ラインに接続される。第1コンデンサおよび第2コンデンサのそれぞれの静電容量値は既知である。電圧検出回路は、前記第1コンデンサの端子間電圧および前記第2コンデンサの端子間電圧を検出する。演算手段は、検出された前記第1コンデンサの端子間電圧および前記第2コンデンサの端子間電圧に予め決められた演算式を適用することによって、被測定面の電位に対応した電圧値を算出する。表示器は算出された電圧値を表示する。 The surface electrometer according to the present invention includes a first fixed electrode, a second fixed electrode, an external connection terminal, a reference potential line, a first capacitor, a second capacitor, a voltage detection circuit, a calculation means, and a display. The first fixed electrode faces the surface to be measured. The second fixed electrode is arranged in a different manner from the first fixed electrode, and faces the surface to be measured at a position closer to the surface to be measured than the first fixed electrode. The reference potential line is connected to the external connection terminal. The first capacitor has one end connected to the first fixed electrode and the other end connected to the reference potential line. The second capacitor has one end connected to the second fixed electrode and the other end connected to the reference potential line. The capacitance values of the first capacitor and the second capacitor are known. The voltage detection circuit detects a voltage between terminals of the first capacitor and a voltage between terminals of the second capacitor. The calculation means calculates a voltage value corresponding to the potential of the surface to be measured by applying a predetermined calculation formula to the detected inter-terminal voltage of the first capacitor and the detected inter-terminal voltage of the second capacitor. . The display unit displays the calculated voltage value.
本発明によれば、表面電位の手軽な測定を実現することができる。 According to the present invention, easy measurement of the surface potential can be realized.
また、被測定面に対する表面電位計の対向姿勢の許容範囲を拡げることができる。 In addition , the permissible range of the posture of the surface electrometer facing the surface to be measured can be expanded.
請求項4の発明によれば、小型軽量の表面電位計を提供することができる。 According to invention of Claim 4 , a small and lightweight surface electrometer can be provided.
図1は本発明に係る表面電位計の前面の構成を示す外観図である。 FIG. 1 is an external view showing the configuration of the front surface of a surface electrometer according to the present invention.
表面電位計1は、図の上下方向に長い略直方体の外形をもつ所謂手のひらサイズの携帯可能な測定器である。樹脂製の筐体10の前面に、所定桁の数(図では5桁)の表示が可能な液晶表示器45と、操作者が測定開始を指示するための押しボタン式の操作入力スイッチ46とが配置されている。また、筐体10の下端面には内部の基準電位ラインを接地するための外部接続端子51が配置されている。 The surface electrometer 1 is a so-called palm-sized portable measuring instrument having a substantially rectangular parallelepiped outer shape that is long in the vertical direction in the figure. A liquid crystal display 45 capable of displaying a predetermined number of digits (five digits in the figure) on the front surface of the resin casing 10, a push button type operation input switch 46 for an operator to instruct the start of measurement, Is arranged. An external connection terminal 51 for grounding an internal reference potential line is disposed on the lower end surface of the housing 10.
図2は表面電位計の背面の構成を示す外観図であり、図3は図2のa−a矢視断面図である。図2では導体膜の構成を示すために筐体10の一部を切り欠いてある。 2 is an external view showing the configuration of the back surface of the surface electrometer, and FIG. 3 is a cross-sectional view taken along the line aa in FIG. In FIG. 2, a part of the housing 10 is cut away to show the configuration of the conductor film.
表面電位計1の背面の上端側に第1固定電極11および第2固定電極12が配置されている。第1固定電極11および第2固定電極12は銅または他の金属からなる略四角形の平板状の導電体である。第2固定電極12は、2個の導電体121,122からなり、これら導電体121,122は第1固定電極11に対して筐体10の短尺方向(図の左右方向)の一方側と他方側とに振り分けて配置されている。つまり、導電体121と導電体122との間に第1固定電極11が位置する。導電体121,122のそれぞれの平面積はともに第1固定電極11の平面積の1/2である。 A first fixed electrode 11 and a second fixed electrode 12 are arranged on the upper end side of the back surface of the surface electrometer 1. The first fixed electrode 11 and the second fixed electrode 12 are substantially rectangular flat-plate conductors made of copper or another metal. The second fixed electrode 12 includes two conductors 121 and 122, and these conductors 121 and 122 are on one side and the other side in the short direction (left and right direction in the figure) of the housing 10 with respect to the first fixed electrode 11. They are arranged separately from each other. That is, the first fixed electrode 11 is located between the conductor 121 and the conductor 122. The planar area of each of the conductors 121 and 122 is ½ of the planar area of the first fixed electrode 11.
第1固定電極11および第2固定電極12に関して最も重要な事項は、第1固定電極11と第2固定電極12とが、互いに重ならずかつ第2固定電極12が第1固定電極11よりも被測定面8に近づくように段違いに平行配置されていることである(図3参照)。つまり、表面電位計1の背面は平坦面ではなく、第1固定電極11の配置される部分が窪んだ段差面になっている。第1固定電極11と第2固定電極12との間の高低差、すなわち表面電位計1の背面における段差gの値は5mm程度である。 The most important matters regarding the first fixed electrode 11 and the second fixed electrode 12 are that the first fixed electrode 11 and the second fixed electrode 12 do not overlap each other, and the second fixed electrode 12 is more than the first fixed electrode 11. It is arranged in parallel so as to approach the surface 8 to be measured (see FIG. 3). That is, the back surface of the surface electrometer 1 is not a flat surface but a stepped surface in which a portion where the first fixed electrode 11 is disposed is recessed. The height difference between the first fixed electrode 11 and the second fixed electrode 12, that is, the value of the step g on the back surface of the surface electrometer 1 is about 5 mm.
このような第1固定電極11および第2固定電極12を囲むように筐体10の内面に導電膜52が設けられている。導電膜52は外部接続端子51と導通しており、シャーシーアースとして用いられる。 A conductive film 52 is provided on the inner surface of the housing 10 so as to surround the first fixed electrode 11 and the second fixed electrode 12. The conductive film 52 is electrically connected to the external connection terminal 51 and is used as a chassis ground.
なお、筐体10の背面の下端側には、バッテリー交換のための開閉部10Aが設けられている。 An opening / closing part 10A for battery replacement is provided on the lower end side of the rear surface of the housing 10.
以上の表面電位計1の構成に関して種々の変形が可能である。例えば、筐体10を金属で構成し、導電膜52に代えて適切な絶縁膜を設けてもよい。導電膜52を第1固定電極11および第2固定電極12の近傍のみに配置してもよい。第1固定電極11および第2固定電極12の形状は四角形に限らず、円形、楕円形および他の形状でもよい。第2固定電極12を第1固定電極11の上下左右に配置した計4個の導電体で構成してもよい。第2固定電極12は第1固定電極11を囲む環状であってもよい。外部接続端子51は基準電位ラインと導通しかつ外界に露出した導体であればよい。 Various modifications can be made to the configuration of the surface electrometer 1 described above. For example, the housing 10 may be made of metal, and an appropriate insulating film may be provided instead of the conductive film 52. The conductive film 52 may be disposed only in the vicinity of the first fixed electrode 11 and the second fixed electrode 12. The shape of the first fixed electrode 11 and the second fixed electrode 12 is not limited to a quadrangle, and may be a circle, an ellipse, and other shapes. The second fixed electrode 12 may be composed of a total of four conductors arranged on the top, bottom, left and right of the first fixed electrode 11. The second fixed electrode 12 may have an annular shape surrounding the first fixed electrode 11. The external connection terminal 51 may be a conductor that is electrically connected to the reference potential line and exposed to the outside.
図4は本発明に係る測定原理の説明図である。 FIG. 4 is an explanatory diagram of the measurement principle according to the present invention.
表面電位計の内部において、第1固定電極と基準電位ラインとの間および第2固定電極と基準電位ラインとの間にそれぞれ静電容量値Csのコンデンサが接続されている。Csの具体値は1000pF〜10000pFである。このような表面電位計を物体の前方に配置すると、物体表面の電荷の影響を受けて第1固定電極および第2固定電極に誘導電位が生じ、これにともなって2つのコンデンサの端子間に電圧が生じる。 Inside the surface potentiometer, a capacitor having a capacitance value Cs is connected between the first fixed electrode and the reference potential line and between the second fixed electrode and the reference potential line. Specific values of Cs are 1000 pF to 10000 pF. When such a surface potential meter is arranged in front of the object, an induced potential is generated in the first fixed electrode and the second fixed electrode due to the influence of the charge on the object surface, and accordingly, a voltage is generated between the terminals of the two capacitors. Occurs.
誘導電位は第1固定電極および第2固定電極のそれぞれと物体との距離D1,D2に依存する。ここで、第2固定電極と物体との間における静電容量値をCxとすると、第1固定電極と物体との間おける静電容量値は、Cxと電極配置の段差gに応じた静電容量値Cgとの合成値になる。 The induced potential depends on the distances D1 and D2 between the first fixed electrode and the second fixed electrode and the object. Here, when the capacitance value between the second fixed electrode and the object is Cx, the capacitance value between the first fixed electrode and the object is an electrostatic capacity corresponding to the step g of Cx and the electrode arrangement. It becomes a composite value with the capacitance value Cg.
第1固定電極側のコンデンサの端子間電圧をV1、第2固定電極側のコンデンサの端子間電圧をV2とすると、物体の表面電位に相当する電圧である物体と基準電位ラインとの間の電圧Vxは以下のようにV1,V2で特定される。
V1=(Vx/Cs)/(1/Cx+1/Cg+1/Cs)
V2=(Vx/Cs)/(1/Cx+1/Cs)
Cx,Cg《 Csならば
V1=(Vx/Cs)/(1/Cx+1/Cg) …(1)
V2=(Vx/Cs)/(1/Cx) …(2)
式(1)を変形すると
V1(1/Cx+1/Cg)=(Vx/Cs)
V1/Cx=(Vx/Cs)−V1/Cg
1/Cx=(Vx/Cs−V1/Cg)/V1 …(3)
式(2)を変形すると
V2/Cx=(Vx/Cs)
1/Cx=(Vx/Cs)/V2 …(4)
式(3)および式(4)から
(Vx/Cs−V1/Cg)/V1=(Vx/Cs)/V2
(Vx/Cs−V1/Cg)V2=(Vx/Cs)V1
(Vx/Cs)V2−(V1/Cg)V2=(Vx/Cs)V1
(Vx/Cs)V2−(Vx/Cs)V1=(V1/Cg)V2
Vx(V2/Cs−V1/Cs)=(V1/Cg)V2
Vx=(V1/Cg)V2/(V2/Cs−V1/Cs)
Vx=(V1・V2/Cg)/(V2−V1)/Cs
Vx=(Cs/Cg)・(V1・V2)/(V2−V1) …(5)
式(5)が示すとおり、電圧Vxは距離D2に依存する静電容量値Cxを含まない式で表され、電圧V1,V2から電圧Vxを算出することができる。つまり、表面電位計と物体とを厳密に位置決めすることなく表面電位を測定することができる。
When the voltage between the terminals of the capacitor on the first fixed electrode side is V1, and the voltage between the terminals of the capacitor on the second fixed electrode side is V2, the voltage between the object and the reference potential line, which is a voltage corresponding to the surface potential of the object Vx is specified by V1 and V2 as follows.
V1 = (Vx / Cs) / (1 / Cx + 1 / Cg + 1 / Cs)
V2 = (Vx / Cs) / (1 / Cx + 1 / Cs)
If Cx, Cg << Cs, V1 = (Vx / Cs) / (1 / Cx + 1 / Cg) (1)
V2 = (Vx / Cs) / (1 / Cx) (2)
When formula (1) is transformed, V1 (1 / Cx + 1 / Cg) = (Vx / Cs)
V1 / Cx = (Vx / Cs) -V1 / Cg
1 / Cx = (Vx / Cs−V1 / Cg) / V1 (3)
When equation (2) is transformed, V2 / Cx = (Vx / Cs)
1 / Cx = (Vx / Cs) / V2 (4)
From Expressions (3) and (4), (Vx / Cs−V1 / Cg) / V1 = (Vx / Cs) / V2
(Vx / Cs−V1 / Cg) V2 = (Vx / Cs) V1
(Vx / Cs) V2- (V1 / Cg) V2 = (Vx / Cs) V1
(Vx / Cs) V2- (Vx / Cs) V1 = (V1 / Cg) V2
Vx (V2 / Cs-V1 / Cs) = (V1 / Cg) V2
Vx = (V1 / Cg) V2 / (V2 / Cs−V1 / Cs)
Vx = (V1 · V2 / Cg) / (V2−V1) / Cs
Vx = (Cs / Cg) · (V1 · V2) / (V2−V1) (5)
As shown in Expression (5), the voltage Vx is expressed by an expression that does not include the capacitance value Cx that depends on the distance D2, and the voltage Vx can be calculated from the voltages V1 and V2. That is, the surface potential can be measured without strictly positioning the surface potential meter and the object.
Csは使用するコンデンサに固有の既知の値であり、Cgも電極配置で決まる固定の段差gに応じた既知の値である。しかし、実際にはCsに若干のばらつきがあり、Cgに設計値との誤差がある。したがって、Cs/Cgを定数kとし、校正によってkを決めるのが望ましい。つまり、次の式(6)を適用することによって、より正確に物体の表面電位を測定することができる。
Vx=k(V1・V2)/(V2−V1) …(6)
ここで、空気の比誘電率は8.854×10-12F/mであるので、例えば30mm角の電極を物体から50mm離して配置したときの物体と電極との間の静電容量値は0.2pF程度である。コンデンサの静電容量値Csが1000pFのコンデンサを使用したときの電圧Vxに対するコンデンサの端子間電圧(V2)の分圧比は5×103となる。したがって、端子間電圧の測定に分解能1mVの検出回路を用いた場合、表面電位測定の分解能は5Vである。これは一般的な要求(分解能10V)を十分に満たす。
Cs is a known value specific to the capacitor to be used, and Cg is also a known value corresponding to a fixed step g determined by the electrode arrangement. However, there is actually a slight variation in Cs, and Cg has an error from the design value. Therefore, it is desirable to set Cs / Cg to a constant k and determine k by calibration. That is, the surface potential of the object can be measured more accurately by applying the following equation (6).
Vx = k (V1 · V2) / (V2−V1) (6)
Here, since the relative dielectric constant of air is 8.854 × 10 −12 F / m, for example, when a 30 mm square electrode is placed 50 mm away from the object, the capacitance value between the object and the electrode is It is about 0.2 pF. When a capacitor having a capacitance value Cs of 1000 pF is used, the voltage dividing ratio of the capacitor terminal voltage (V2) to the voltage Vx is 5 × 10 3 . Therefore, when a detection circuit having a resolution of 1 mV is used for measuring the voltage between the terminals, the resolution of the surface potential measurement is 5V. This sufficiently satisfies the general requirement (resolution 10V).
1000pFのコンデンサの安定度は100秒で電圧が1mV変動する程度かそれよりも良好である。フルスケールを±500とすれば、1/10FSは50である。物体との距離(測定ギャップ)が5cmのとき、段差gが5mmの構成において発生する測定誤差は51/49〜49/51、すなわち±4%以内になる。 The stability of a 1000 pF capacitor is as good as or better than a voltage fluctuation of 1 mV in 100 seconds. If the full scale is ± 500, 1/10 FS is 50. When the distance to the object (measurement gap) is 5 cm, the measurement error occurring in the configuration where the step g is 5 mm is 51/49 to 49/51, that is, within ± 4%.
図5は表面電位計の機能構成を示す回路図である。 FIG. 5 is a circuit diagram showing a functional configuration of the surface electrometer.
表面電位計1は、第1固定電極11、第2固定電極12、外部接続端子51、基準電位ライン52、第1コンデンサ21、第2コンデンサ22、電圧検出回路30、プロセッサ(CPU)40、表示器45、操作入力スイッチ46、直流電源47、バッテリー48、クロックジェネレータ49、第1導通路61、および第2導通路62を備える。 The surface electrometer 1 includes a first fixed electrode 11, a second fixed electrode 12, an external connection terminal 51, a reference potential line 52, a first capacitor 21, a second capacitor 22, a voltage detection circuit 30, a processor (CPU) 40, a display. 45, an operation input switch 46, a DC power supply 47, a battery 48, a clock generator 49, a first conduction path 61, and a second conduction path 62.
上述したとおり、第1固定電極11および第2固定電極12は段違いに配置され、基準電位ライン52は外部接続端子51に接続されている。 As described above, the first fixed electrode 11 and the second fixed electrode 12 are arranged in steps, and the reference potential line 52 is connected to the external connection terminal 51.
第1コンデンサ21は、その一端が第1固定電極11に接続され、その他端が基準電位ライン52に接続される。第2コンデンサ22は、その一端が第2固定電極12に接続され、その他端が基準電位ライン52に接続される。第1コンデンサ21の静電容量値(Cs)は第2コンデンサ22の静電容量値(Cs)と等しい。 The first capacitor 21 has one end connected to the first fixed electrode 11 and the other end connected to the reference potential line 52. The second capacitor 22 has one end connected to the second fixed electrode 12 and the other end connected to the reference potential line 52. The capacitance value (Cs) of the first capacitor 21 is equal to the capacitance value (Cs) of the second capacitor 22.
電圧検出回路30は、2つの演算増幅器31,32を中心に構成され、ゲイン調整および零出力調整のためのフィードバック回路を備える。演算増幅器31は第1コンデンサ21の端子間電圧(V1)に応じた検出信号をプロセッサ40に出力し、演算増幅器32は第2コンデンサ22の端子間電圧(V2)に応じた検出信号をプロセッサ40に出力する。 The voltage detection circuit 30 is configured around two operational amplifiers 31 and 32, and includes a feedback circuit for gain adjustment and zero output adjustment. The operational amplifier 31 outputs a detection signal corresponding to the inter-terminal voltage (V1) of the first capacitor 21 to the processor 40, and the operational amplifier 32 outputs the detection signal corresponding to the inter-terminal voltage (V2) of the second capacitor 22 to the processor 40. Output to.
プロセッサ40は、予め記録されたプログラムを実行するマイクロコンピュータであり、演算手段401およびリセット制御手段402の機能を備える。演算手段401は、電圧検出回路30からの検出信号が表す第1コンデンサ21の端子間電圧および第2コンデンサ22の端子間電圧に上述の式(6)を適用することによって、被測定面の電位に対応した電圧値を算出する。リセット制御手段402は、操作入力スイッチ46のオン操作に呼応して第1導通路61および第2導通路62を閉じ、一定時間の経過後に開く。 The processor 40 is a microcomputer that executes a pre-recorded program, and includes the functions of a calculation unit 401 and a reset control unit 402. The calculation means 401 applies the above-described equation (6) to the voltage between the terminals of the first capacitor 21 and the voltage between the terminals of the second capacitor 22 represented by the detection signal from the voltage detection circuit 30, thereby calculating the potential of the measured surface. The voltage value corresponding to is calculated. The reset control unit 402 closes the first conduction path 61 and the second conduction path 62 in response to the ON operation of the operation input switch 46 and opens it after a lapse of a fixed time.
表示器45は、演算手段401によって算出された電圧値を測定結果として表示する。操作入力スイッチ46は、操作状態に応じた信号をプロセッサ40に与える。直流電源47はバッテリー48からの電力に基づいて±5Vの駆動電圧を発生させてプロセッサ40および電圧検出回路30に供給する。クロックジェネレータ49はプロセッサ40に動作クロックを与える。 The display unit 45 displays the voltage value calculated by the calculation unit 401 as a measurement result. The operation input switch 46 gives a signal corresponding to the operation state to the processor 40. The DC power supply 47 generates a drive voltage of ± 5 V based on the power from the battery 48 and supplies it to the processor 40 and the voltage detection circuit 30. The clock generator 49 provides an operation clock to the processor 40.
第1導通路61および第2導通路62は、プロセッサ40からの制御信号S61,S62に従って動作するスイッチからなる。スイッチとしてリレーが好適であるが、半導体スイッチであってもよい。スイッチと直列に抵抗を挿入する場合もある。第1導通路61が閉じると、基準電位ライン52と第1コンデンサ21とを通る閉ループが形成され、第1コンデンサ21の蓄積電荷が基準電位ライン52へ放出される。同様に第2導通路62が閉じると、第2コンデンサ22の蓄積電荷が基準電位ライン52へ放出される。つまり、第1導通路61および第2導通路62は、第1コンデンサ21および第2コンデンサ22のそれぞれの端子間電圧を零に戻すリセットのための手段である。 The first conduction path 61 and the second conduction path 62 are composed of switches that operate in accordance with control signals S61 and S62 from the processor 40. A relay is suitable as the switch, but it may be a semiconductor switch. In some cases, a resistor is inserted in series with the switch. When the first conduction path 61 is closed, a closed loop passing through the reference potential line 52 and the first capacitor 21 is formed, and the accumulated charge of the first capacitor 21 is discharged to the reference potential line 52. Similarly, when the second conduction path 62 is closed, the accumulated charge of the second capacitor 22 is discharged to the reference potential line 52. That is, the first conduction path 61 and the second conduction path 62 are means for resetting the voltages across the terminals of the first capacitor 21 and the second capacitor 22 to zero.
表面電位計1による測定は次の手順で行われる。 Measurement with the surface electrometer 1 is performed in the following procedure.
測定準備として、外部接続端子51と外部の接地電位ラインとを導線などによって接続し、基準電位ラインを接地しておく。 As a measurement preparation, the external connection terminal 51 and an external ground potential line are connected by a conducting wire or the like, and the reference potential line is grounded.
操作者は、操作入力スイッチ46を操作して測定開始を指示する。指示を受けてプロセッサ40は第1コンデンサ21および第2コンデンサ22をリセットする。リセットは瞬時に終了し、第1導通路61および第2導通路62が開かれて表面電位計1は測定可能なスタンバイ状態になる。 The operator operates the operation input switch 46 to instruct the start of measurement. In response to the instruction, the processor 40 resets the first capacitor 21 and the second capacitor 22. The reset ends instantaneously, the first conduction path 61 and the second conduction path 62 are opened, and the surface electrometer 1 enters a measurable standby state.
測定開始指示に続いて、先立って、または並行して、操作者は指示表面電位計1の背面を被測定面に向けて表面電位計1を被測定面に近づける。表面電位計1は片手で保持できる。被測定面に接触させないように気をつけて、被測定面から数cm〜10cm程度離れた位置に表面電位計1を配置する。 Prior to or in parallel with the measurement start instruction, the operator brings the surface electrometer 1 close to the surface to be measured with the back surface of the indicating surface electrometer 1 facing the surface to be measured. The surface electrometer 1 can be held with one hand. Care is taken not to contact the surface to be measured, and the surface electrometer 1 is arranged at a position about several cm to 10 cm away from the surface to be measured.
このとき、第1固定電極11および第2固定電極12と被測定面とが平行であるのが好ましいが、所定範囲内で傾いた対向姿勢は許容される。それは、第2固定電極12が第1固定電極11の両側に配置された2個の導電体121,122で構成されるからである。第2固定電極12が第1固定電極11と同様に単一の平板であれば、表面電位計1が大きく傾いたときに、被測定面に対する第1固定電極11と第2固定電極12との遠近関係が正規と逆になる。この条件は演算式の定数kを求める校正における条件と異なるので、正しい測定結果が得られない。これに対して、第2固定電極12が2個の導電体121,122で構成される本構造では、表面電位計1が大きく傾いたときに、導電体121,122の片方は第1固定電極11よりも被測定面から遠くなるものの、残りの片方は傾いていないときよりもさらに被測定面に近づくので、遠近が平均化されることによって適正な測定結果が得られる。 At this time, it is preferable that the first fixed electrode 11 and the second fixed electrode 12 are parallel to the surface to be measured, but an opposing posture inclined within a predetermined range is allowed. This is because the second fixed electrode 12 includes two conductors 121 and 122 arranged on both sides of the first fixed electrode 11. If the second fixed electrode 12 is a single flat plate like the first fixed electrode 11, when the surface electrometer 1 is greatly inclined, the first fixed electrode 11 and the second fixed electrode 12 with respect to the surface to be measured The perspective relationship is reversed from normal. Since this condition is different from the condition in the calibration for obtaining the constant k of the arithmetic expression, a correct measurement result cannot be obtained. On the other hand, in this structure in which the second fixed electrode 12 is composed of the two conductors 121 and 122, when the surface electrometer 1 is largely inclined, one of the conductors 121 and 122 is the first fixed electrode. Although it is farther from the surface to be measured than 11, the remaining one is closer to the surface to be measured than when it is not tilted, so that an appropriate measurement result can be obtained by averaging the perspective.
表面電位計1を高電位の被測定面に対向させると、第1コンデンサ21および第2コンデンサ22の端子間電圧が刻々と変化する。そのとき、端子間電圧は繰り返し検出され、検出値に基づく演算の結果が逐次に表示器45によって表示される。表示される数値は数秒から数十秒でほぼ一定となる。その時点の数値が被測定面の電位、すなわち測定結果を表す。 When the surface electrometer 1 is made to face a surface to be measured having a high potential, the voltage between the terminals of the first capacitor 21 and the second capacitor 22 changes every moment. At that time, the voltage between the terminals is repeatedly detected, and the calculation result based on the detected value is sequentially displayed on the display unit 45. The displayed value is almost constant from several seconds to several tens of seconds. The numerical value at that time represents the potential of the surface to be measured, that is, the measurement result.
操作者が操作入力スイッチ46を操作する度に測定が再開される。以前と異なる物体の表面電位を測定したければ、表面電位計1を適宜に移動させて所望の被測定面に対向させればよい。 Measurement is resumed each time the operator operates the operation input switch 46. If it is desired to measure the surface potential of an object different from the previous one, the surface potential meter 1 may be appropriately moved so as to face the desired surface to be measured.
表面電位計1の仕様の一例は次のとおりである。
測定電圧: 10V〜20kV
レンジ切替え:オート(例えば感度を1200V以上で1桁落とし1000V以下で1桁上げる)
測定精度: ±5%以上
電源管理: オートパワーオフ(デフォルトは最終操作から3分後にパワーオフ)
以上の実施形態によれば、表面電位計1を被測定面に対向させて測定開始を指示するという簡単な操作で表面電位を測定することができる。表面電位計1は振動電極も高電圧源ももたないので、小型軽量化が可能である。
An example of the specifications of the surface electrometer 1 is as follows.
Measurement voltage: 10V ~ 20kV
Range switching: Auto (for example, the sensitivity drops by 1 digit at 1200V or higher and increases by 1 digit at 1000V or lower)
Measurement accuracy: ± 5% or more Power management: Auto power off (Default is power off 3 minutes after final operation)
According to the above embodiment, the surface potential can be measured by a simple operation in which the surface electrometer 1 is opposed to the surface to be measured and the start of measurement is instructed. Since the surface electrometer 1 has neither a vibrating electrode nor a high voltage source, it can be reduced in size and weight.
上述の実施形態では、第1コンデンサ21と第2コンデンサ22がともに静電容量値Csをもつ構成を例示したが、2つのコンデンサの間で静電容量値が異なる構成であっても表面電位の測定は可能である。例えば第1コンデンサ21の静電容量値をCs,第2コンデンサ22の静電容量値をCs’(=aCs)とすると、上記式(6)は次式に置き換わる。
Vx=k(V1・V2)/(V2−V1/a) …(6’)
この式(6’)の適用によって表面電位を算出することができる。
ここで、静電容量値Csと静電容量値Cs’との関係を、表面電位計1の背面と被測定面とが平行であるときに電圧V1と電圧V2との比が所定値(例えば1)となるようにCgを考慮して選定するのが好ましい。測定に際して、電圧V1と電圧V2との比が所定値またはそれに近い値であるかどうかを検知し、表面電位計1の背面と被測定面とが平行である旨をランプなどで表示すれば、操作者が表面電位計1を好ましい姿勢に容易に配置することができ、より手軽に正確な測定を行うことができる。
In the above-described embodiment, the configuration in which both the first capacitor 21 and the second capacitor 22 have the capacitance value Cs is illustrated. However, even if the capacitance value is different between the two capacitors, the surface potential can be reduced. Measurement is possible. For example, when the capacitance value of the first capacitor 21 is Cs and the capacitance value of the second capacitor 22 is Cs ′ (= aCs), the above equation (6) is replaced by the following equation.
Vx = k (V1 · V2) / (V2−V1 / a) (6 ′)
By applying this formula (6 ′), the surface potential can be calculated.
Here, the relationship between the capacitance value Cs and the capacitance value Cs ′ is such that the ratio between the voltage V1 and the voltage V2 when the back surface of the surface electrometer 1 and the surface to be measured are parallel is a predetermined value (for example, It is preferable to select in consideration of Cg so as to satisfy 1). At the time of measurement, if it is detected whether the ratio of the voltage V1 and the voltage V2 is a predetermined value or a value close thereto, and the fact that the back surface of the surface electrometer 1 and the surface to be measured are parallel is displayed with a lamp or the like, The operator can easily place the surface electrometer 1 in a preferred posture, and more accurate measurement can be performed more easily.
上述の実施形態において、表面電位計1の構成、形状、各部の材質、寸法、静電容量値などの構造条件、表面電位計1の仕様、および測定手順は例示に限定されず、本発明の主旨に沿う範囲内で種々の変更が可能である。例えば、第1導通路61および第2導通路62をリレー回路とし、電源オフ状態では第1コンデンサ21および第2コンデンサ22をリセットするように閉じかつ電源オンに呼応して開く構成としてもよい。 In the above-described embodiment, the configuration of the surface electrometer 1, the shape, the material conditions of each part, the dimensions, the capacitance conditions and other structural conditions, the specifications of the surface electrometer 1, and the measurement procedure are not limited to examples, and Various changes can be made within the scope of the gist. For example, the first conduction path 61 and the second conduction path 62 may be relay circuits, and in a power-off state, the first capacitor 21 and the second capacitor 22 may be closed and reset in response to power-on.
本発明は、半導体や液晶パネルに代表される比較的に静電気に弱い部品や製品の製造ラインにおける静電気チェック、イオナイザーや帯電チャージャの評価、フィルムや樹脂などの帯電し易い部材の帯電チェックなどの各種の用途に好適である。 The present invention includes various checks such as a static check in a production line for relatively weak parts and products represented by semiconductors and liquid crystal panels, an evaluation of an ionizer and a charge charger, and a charge check of an easily charged member such as a film or resin. It is suitable for use.
1 表面電位計
8 被測定面
10 筐体
11 第1固定電極
12 第2固定電極
121,122 導電体
21 第1コンデンサ
22 第2コンデンサ
52 基準電位ライン
Cs 静電容量値
V1 第1コンデンサの端子間電圧
V2 第2コンデンサの端子間電圧
Vx 被測定面の電位に対応した電圧値
51 外部接続端子
30 電圧検出回路
401 演算手段
45 表示器
46 操作入力スイッチ
61 第1導通路
62 第2導通路
501 リセット制御手段
DESCRIPTION OF SYMBOLS 1 Surface potential meter 8 Surface to be measured 10 Housing | casing 11 1st fixed electrode 12 2nd fixed electrode 121,122 Conductor 21 1st capacitor 22 2nd capacitor 52 Reference potential line Cs Capacitance value V1 Between terminals of 1st capacitor Voltage V2 Voltage between terminals of the second capacitor Vx Voltage value corresponding to the potential of the surface to be measured 51 External connection terminal 30 Voltage detection circuit 401 Calculation means 45 Display 46 Operation input switch 61 First conduction path 62 Second conduction path 501 Reset Control means
Claims (4)
被測定面と対向する第1固定電極と、
前記第1固定電極と段違いに配置され、前記第1固定電極よりも前記被測定面に近い位置で前記被測定面と対向する第2固定電極と、
接地のための外部接続端子と、
前記外部接続端子に接続された基準電位ラインと、
前記第1固定電極に一端が接続され、前記基準電位ラインに他端が接続された第1コンデンサと、
前記第2固定電極に一端が接続され、前記基準電位ラインに他端が接続された第2コンデンサと、
前記第1コンデンサの端子間電圧および前記第2コンデンサの端子間電圧を検出する電圧検出回路と、
検出された前記第1コンデンサの端子間電圧および前記第2コンデンサの端子間電圧に予め決められた演算式を適用することによって、前記被測定面の電位に対応した電圧値を算出する演算手段と、
算出された電圧値を表示する表示器とを備え、
前記第2固定電極は、前記第1固定電極の両側に振り分けて配置され且つ電気的に接続された2個の導電体からなる
ことを特徴とする表面電位計。 A surface potentiometer for measuring the surface potential of an object,
A first fixed electrode facing the surface to be measured;
A second fixed electrode that is arranged in a step different from the first fixed electrode and faces the measured surface at a position closer to the measured surface than the first fixed electrode;
An external connection terminal for grounding,
A reference potential line connected to the external connection terminal;
A first capacitor having one end connected to the first fixed electrode and the other end connected to the reference potential line;
A second capacitor having one end connected to the second fixed electrode and the other end connected to the reference potential line;
A voltage detection circuit for detecting a voltage between terminals of the first capacitor and a voltage between terminals of the second capacitor;
Calculating means for calculating a voltage value corresponding to the potential of the surface to be measured by applying a predetermined calculation formula to the detected inter-terminal voltage of the first capacitor and the detected inter-terminal voltage of the second capacitor; ,
An indicator that displays the calculated voltage value ,
The surface potential meter according to claim 2, wherein the second fixed electrode is composed of two conductors arranged and arranged on both sides of the first fixed electrode .
前記演算式は
Vx=k(V1・V2)/(V2−V1)
ただし、Vx:被測定面の電位に対応した電圧値
k:定数、
V1:第1コンデンサの端子間電圧、
V2:第2コンデンサの端子間電圧
である
請求項1記載の表面電位計。 The capacitance value of the first capacitor and the capacitance value of the second capacitor are equal,
The arithmetic expression is Vx = k (V1 · V2) / (V2−V1)
Where Vx: voltage value corresponding to the potential of the surface to be measured
k: constant,
V1: voltage between terminals of the first capacitor,
The surface potential meter according to claim 1, wherein V2 is a voltage between terminals of the second capacitor.
前記第1コンデンサと並列に前記第1固定電極および前記基準電位ラインに接続された開閉可能な第1導通路と、
前記第2コンデンサと並列に前記第2固定電極および前記基準電位ラインに接続された開閉可能な第2導通路と、
前記操作入力スイッチのオン操作に呼応して前記第1導通路および第2導通路を閉じ、一定時間の経過後に開くリセット制御手段とを備える
請求項1または2記載の表面電位計。 An operation input switch for the operator to instruct the start of measurement;
A first conductive path that can be opened and closed connected to the first fixed electrode and the reference potential line in parallel with the first capacitor;
A switchable second conduction path connected to the second fixed electrode and the reference potential line in parallel with the second capacitor;
The operation in response to the input switch-on operation to close the first conduction path and the second conduction path, according to claim 1 or 2 the surface potential meter according and a reset control means for opening after a fixed time.
前記筐体の前面に前記表示器が配置され、
前記筐体の背面に前記第1固定電極および第2固定電極が配置され、
携帯可能に構成されてなる
請求項1ないし請求項3のいずれかに記載の表面電位計。 A housing for accommodating the voltage detection circuit and the calculation means;
The indicator is disposed on the front surface of the housing,
The first fixed electrode and the second fixed electrode are disposed on a back surface of the housing;
Surface potential meter according to any one of the mobile so that it may be configured claims 1 to 3.
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