JP7032013B1

JP7032013B1 - Capacitance measuring device

Info

Publication number: JP7032013B1
Application number: JP2021168906A
Authority: JP
Inventors: 幸明斉藤
Original assignee: 幸明斉藤
Priority date: 2021-10-14
Filing date: 2021-10-14
Publication date: 2022-03-08
Anticipated expiration: 2041-10-14
Also published as: JP2023059034A

Abstract

PROBLEM TO BE SOLVED: To measure the height of a liquid, a granular material, a powder or the like more accurately in a wide measurement range, and to measure the relative permittivity of a substance between electrodes.
SOLUTION: A uniform capacitor and a first to P (P is an integer of 3 or more) periodic capacitors are provided. The uniform capacitor and the first to P (P is an integer of 3 or more) periodic capacitors are capacitors composed of a read electrode extending in the longitudinal direction and a counter electrode facing the read electrode, respectively. In the uniform capacitor, both the distance between the counter electrode and the read electrode and the width of the read electrode along the direction orthogonal to the longitudinal direction are uniform. In the first to P-periodic capacitors, either or both of the distance between the counter electrode and the read electrode and the width of the read electrode along the direction orthogonal to the longitudinal direction changes in a periodic function. Here, in the periodic functions shown by the first to P periodic capacitors, the difference between the maximum value and the minimum value and the period L are common to each other, and the initial phases are different from each other.
[Selection diagram] Fig. 1

Description

この発明は、水位の測定に用いられる静電容量式の水位センサなど、静電容量を測定する静電容量測定装置に関する。 The present invention relates to a capacitance measuring device for measuring a capacitance, such as a capacitance type water level sensor used for measuring a water level.

液体の水位を測定する水位計として、静電容量式の水位センサがある（例えば、特許文献１参照）。 As a water level gauge for measuring the water level of a liquid, there is a capacitance type water level sensor (see, for example, Patent Document 1).

従来の静電容量式の水位センサの概略を説明する。面積Ｓの２枚の電極が、互いに平行に、距離ｄだけ離して配置されたコンデンサの静電容量Ｃは、以下の式（１）で与えられる。 The outline of the conventional capacitance type water level sensor will be described. The capacitance C of the capacitor in which the two electrodes having the area S are arranged parallel to each other and separated by a distance d is given by the following equation (1).

ここで、εｒは比誘電率である。比誘電率εｒは、真空の誘電率ε０に対する、電極間の物質の誘電率εの比（εｒ／ε０）である。例えば、空気の比誘電率εｒ（ａｉｒ）は１程度である。これに対し、水の比誘電率εｒ（ｗａｔｅｒ）は８０程度であり、空気の比誘電率εｒ（ａｉｒ）に比べて非常に大きい。 Here, εr is the relative permittivity. The relative permittivity εr is the ratio (εr / ε0) of the permittivity ε of the substance between the electrodes to the permittivity ε0 of the vacuum. For example, the relative permittivity εr (air) of air is about 1. On the other hand, the relative permittivity εr (water) of water is about 80, which is much larger than the relative permittivity εr (air) of air.

このため、電極対を高さ方向に延在するように設けると、浸水する電極の面積、すなわち、水位によってコンデンサの静電容量が変化する。従って、静電容量を測定することにより、水位を測定することができる。 Therefore, if the electrode pair is provided so as to extend in the height direction, the capacitance of the capacitor changes depending on the area of the electrode to be flooded, that is, the water level. Therefore, the water level can be measured by measuring the capacitance.

しかし、静電容量式の水位センサで測定される静電容量は、上記式（１）からわかるように、水位だけでなく、液体の誘電率によっても値が変わる。このため、液体の誘電率が一定でない場合など、正確な水位を求める工夫が必要である。 However, as can be seen from the above equation (1), the capacitance measured by the capacitance type water level sensor changes not only by the water level but also by the dielectric constant of the liquid. Therefore, it is necessary to devise to obtain an accurate water level, such as when the dielectric constant of the liquid is not constant.

正確な水位を求めるために、基準電極を用いて較正する技術がある。ここで用いられる基準電極は、完全に浸水していなければならない。 There is a technique to calibrate using a reference electrode to obtain an accurate water level. The reference electrode used here must be completely submerged.

特開２０１８－１７９８５８号公報Japanese Unexamined Patent Publication No. 2018-179858

しかしながら、上述した基準電極を用いる較正では、基準電極と測定電極の電気容量の比から水位を得るため、この比が大きいと誤差が大きくなる。従って、高い水位をより正確に測定するには、基準電極を大きくする必要がある。その一方、基準電極は完全に浸水している必要があるため、大きさに制限がある。従って、従来の静電容量式の水位センサにおいて、広い測定範囲の水位を正確に測定することは難しい。 However, in the calibration using the reference electrode described above, the water level is obtained from the ratio of the electric capacities of the reference electrode and the measurement electrode, so that the error becomes large when this ratio is large. Therefore, in order to measure the high water level more accurately, it is necessary to make the reference electrode larger. On the other hand, the reference electrode needs to be completely submerged, so its size is limited. Therefore, it is difficult to accurately measure the water level in a wide measurement range with the conventional capacitive water level sensor.

また、水以外の液体や、粒体、粉体などの高さの測定や、電極間の物質の比誘電率の測定が望まれる場合もある。 In some cases, it may be desired to measure the height of liquids other than water, granules, powders, etc., and the relative permittivity of substances between electrodes.

この発明は、上述の問題点に鑑みてなされたものである。この発明の目的は、液体、粒体、粉体などの高さを広い測定範囲でより正確に測定でき、また、電極間の物質の比誘電率を測定できる静電容量測定装置を提供することにある。 The present invention has been made in view of the above-mentioned problems. An object of the present invention is to provide a capacitance measuring device capable of measuring the height of liquids, granules, powders, etc. more accurately in a wide measuring range and measuring the relative permittivity of substances between electrodes. It is in.

この発明の静電容量測定装置は、均一コンデンサと、第１～第Ｐ（Ｐは３以上の整数）周期コンデンサとを備えて構成される。均一コンデンサと、第１～第Ｐ（Ｐは３以上の整数）周期コンデンサは、それぞれ、長手方向に延在する、読出電極と、読出電極に対向する対向電極とで構成されるコンデンサである。均一コンデンサは、対向電極と読出電極の間隔、及び、読出電極の、長手方向に直交する方向に沿った幅の双方が、均一である。第１～第Ｐ周期コンデンサは、対向電極と読出電極の間隔、及び、読出電極の、長手方向に直交する方向に沿った幅のいずれか一方又は双方が、周期関数状に変化する。ここで、第１～第Ｐ周期コンデンサが示す周期関数は、最大値と最小値との差及び周期Ｌが、互いに共通であり、初期位相が互いに異なる。 The capacitance measuring device of the present invention includes a uniform capacitor and a first to first P (P is an integer of 3 or more) periodic capacitors. The uniform capacitor and the first to P (P is an integer of 3 or more) periodic capacitors are capacitors composed of a read electrode extending in the longitudinal direction and a counter electrode facing the read electrode, respectively. In the uniform capacitor, both the distance between the counter electrode and the read electrode and the width of the read electrode along the direction orthogonal to the longitudinal direction are uniform. In the first to P-periodic capacitors, either or both of the distance between the counter electrode and the read electrode and the width of the read electrode along the direction orthogonal to the longitudinal direction changes in a periodic function. Here, in the periodic functions shown by the first to P periodic capacitors, the difference between the maximum value and the minimum value and the period L are common to each other, and the initial phases are different from each other.

この発明の静電容量測定装置によれば、液体、粒体、粉体などの高さを広い測定範囲でより正確に測定でき、また、電極間の物質の比誘電率を測定できる。 According to the capacitance measuring device of the present invention, the heights of liquids, granules, powders and the like can be measured more accurately in a wide measurement range, and the relative permittivity of substances between electrodes can be measured.

水位センサの原理を説明するための模式図である。It is a schematic diagram for demonstrating the principle of a water level sensor. 電極の他の構成例を説明するための模式図である。It is a schematic diagram for demonstrating another structural example of an electrode. 第１実施例の水位センサを説明するための模式図である。It is a schematic diagram for demonstrating the water level sensor of 1st Example. 測定値にずれがない場合の、周期コンデンサの測定値を示す模式図である。It is a schematic diagram which shows the measured value of a periodic capacitor when there is no deviation in the measured value. 測定値にずれがある場合の、周期コンデンサの測定値を示す模式図である。It is a schematic diagram which shows the measured value of a periodic capacitor when there is a deviation in the measured value. 第２実施例の水位センサを説明するための模式図である。It is a schematic diagram for demonstrating the water level sensor of 2nd Example. 第３実施例の水位センサを説明するための模式図である。It is a schematic diagram for demonstrating the water level sensor of 3rd Embodiment.

以下、図を参照して、この発明の実施の形態について説明するが、各構成要素の形状、大きさ及び配置関係については、この発明が理解できる程度に概略的に示したものに過ぎない。また、以下、この発明の好適な構成例につき説明するが、各構成要素の材質及び数値的条件などは、単なる好適例にすぎない。従って、この発明は以下の実施の形態に限定されるものではなく、この発明の構成の範囲を逸脱せずにこの発明の効果を達成できる多くの変更又は変形を行うことができる。ここでは、コンデンサを構成する一方の電極から他方の電極へ向かう方向をｚ軸、電極の長手方向をｙ軸、ｙ軸及びｚ軸の両者に直交する方向をｘ軸として説明する。なお、ｘ軸は、電極の幅方向に沿った軸である。 Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the shape, size, and arrangement of each component are only schematically shown to the extent that the present invention can be understood. Further, although a suitable configuration example of the present invention will be described below, the material and numerical conditions of each component are merely suitable examples. Therefore, the present invention is not limited to the following embodiments, and many modifications or modifications can be made to achieve the effects of the present invention without departing from the scope of the configuration of the present invention. Here, the direction from one electrode constituting the capacitor to the other electrode will be described as the z-axis, the longitudinal direction of the electrodes will be described as the y-axis, and the direction orthogonal to both the y-axis and the z-axis will be described as the x-axis. The x-axis is an axis along the width direction of the electrode.

（基本原理）
図１を参照して、この発明の静電容量測定装置の一実施形態として水位センサの原理を説明する。図１は、この実施形態の水位センサの原理を説明するための模式図である。 (Basic principle)
With reference to FIG. 1, the principle of the water level sensor will be described as an embodiment of the capacitance measuring device of the present invention. FIG. 1 is a schematic diagram for explaining the principle of the water level sensor of this embodiment.

この実施形態の水位センサは、第１～３周期コンデンサと、均一コンデンサの４つのコンデンサを備えて構成される。各コンデンサは、２枚の電極板が互いに平行に配置された電極対を備えて構成される。 The water level sensor of this embodiment is configured to include four capacitors, a first to third cycle capacitors and a uniform capacitor. Each capacitor is configured with an electrode pair in which two electrode plates are arranged parallel to each other.

以下の説明では、電極対を構成する電極の一方を読出電極と称し、他方を対向電極と称
することもある。対向電極は、対をなす読出電極と同じ形状及び同じ大きさで構成されてもよいし、読出電極よりも大きく構成されてもよい。以下の説明では、電極の形状として読出電極の形状を主に説明し、対向電極の形状等の説明を省略することもある。ここで、各コンデンサが有する対向電極は、一体として構成されていてもよい。また、対向電極は接地（アース）され、接地電極として用いられることもある。 In the following description, one of the electrodes constituting the electrode pair may be referred to as a read electrode, and the other may be referred to as a counter electrode. The counter electrode may be configured to have the same shape and size as the paired read electrode, or may be configured to be larger than the read electrode. In the following description, the shape of the read electrode will be mainly described as the shape of the electrode, and the description of the shape of the counter electrode and the like may be omitted. Here, the counter electrode of each capacitor may be integrally configured. Further, the counter electrode is grounded and may be used as a ground electrode.

図１（Ａ）は、第１周期コンデンサを立体的に示す模式図である。図１（Ｂ）～（Ｄ）は、それぞれ、第１～第３周期コンデンサを構成する読出電極の、概略的な平面図である。図１（Ｅ）は、均一コンデンサを構成する読出電極の、概略的な平面図である。 FIG. 1A is a schematic diagram showing a first-period capacitor in three dimensions. 1 (B) to 1 (D) are schematic plan views of read electrodes constituting the first to third period capacitors, respectively. FIG. 1E is a schematic plan view of a read electrode constituting a uniform capacitor.

先ず、第１～第３周期コンデンサについて説明する。第１～第３周期コンデンサでは、読出電極１２と対向電極１４との間隔、及び、読出電極１２の長手方向に直交する方向に沿った幅のいずれか一方又は双方が、周期関数状に変化する。ここでは、読出電極１２と対向電極１４との間隔ｄが一定であり、幅が周期関数状、ここでは余弦関数状に変化する例を説明する。読出電極１２は、長手方向がほぼ鉛直に配置されるのが好ましい。 First, the first to third period capacitors will be described. In the first to third period capacitors, one or both of the distance between the read electrode 12 and the counter electrode 14 and the width along the direction orthogonal to the longitudinal direction of the read electrode 12 changes in a periodic function. .. Here, an example will be described in which the distance d between the read electrode 12 and the counter electrode 14 is constant, and the width changes in a periodic function shape, here in a cosine function shape. The read electrode 12 is preferably arranged substantially vertically in the longitudinal direction.

第１～３周期コンデンサの読出電極１２ａ～１２ｃは、初期位相が互いに異なっていることを除いて、同じ形状及び同じ大きさで構成される。すなわち、第１～３周期コンデンサの読出電極１２ａ～１２ｃの幅Ｗ_１（ｙ）～Ｗ_３（ｙ）の、平均値、最大値と最小値との差、及び、周期が互いに共通である。初期位相は、互いに異なっていればよいが、互いに均等に、ここでは１２０度（２π／３）ずつずれているのが好ましい。このときの、第１～第３周期コンデンサの読出電極１２ａ～１２ｃの幅Ｗ_１（ｙ）～Ｗ_３（ｙ）は、以下の式（２ａ）～（２ｃ）で表される。 The read electrodes 12a to 12c of the first to third cycle capacitors are configured to have the same shape and the same size except that the initial phases are different from each other. That is, the average value, the difference between the maximum value and the minimum value, and the period of the widths W ₁ (y) to W ₃ (y) of the read electrodes 12a to 12c of the first to third cycle capacitors are common to each other. The initial phases may be different from each other, but are preferably offset evenly, here by 120 degrees (2π / 3). At this time, the widths W ₁ (y) to W ₃ (y) of the read electrodes 12a to 12c of the first to third period capacitors are represented by the following equations (2a) to (2c).

ここで、Ｗ_０は第１～第３周期コンデンサの読出電極１２ａ～１２ｃの平均幅であり、Ｌは周期関数の周期であり、Ｒは周期関数の最大値と最小値の差の１／２である。また、φ１０及びφ２０は、それぞれ、第２及び第３周期コンデンサにおける初期位相である。 Here, W ₀ is the average width of the read electrodes 12a to 12c of the first to third periodic capacitors, L is the period of the periodic function, and R is 1/2 of the difference between the maximum value and the minimum value of the periodic function. Is. Further, φ10 and φ20 are initial phases in the second and third period capacitors, respectively.

なお、ここで示す例のように、周期関数が余弦関数の場合は、Ｒは余弦関数の振幅に対応する。また、図１（Ｂ）～（Ｄ）に示されるように、初期位相が互いに１２０度（２π／３）ずつずれている場合、初期位相φ１０及びφ２０は、それぞれ、２π／３、及び、－２π／３となる。 When the periodic function is a cosine function as in the example shown here, R corresponds to the amplitude of the cosine function. Further, as shown in FIGS. 1B to 1D, when the initial phases are shifted by 120 degrees (2π / 3) from each other, the initial phases φ10 and φ20 are 2π / 3 and −, respectively. It becomes 2π / 3.

水位がｈであるとき、第１～第３周期コンデンサの読出電極１２ａ～１２ｃの浸水部分
の面積Ｓ_１（ｈ）～Ｓ_３（ｈ）は、以下の式（３ａ）～（３ｃ）で与えられる。 When the water level is h, the areas S1 (h) to _S3 ₍ h) of the flooded portion of the read electrodes 12a to 12c of the first to third period capacitors are given by the following equations (3a) to (3c). Be done.

次に、均一コンデンサについて説明する。均一コンデンサでは、読出電極と対向電極との間隔、及び、読出電極の長手方向に直交する方向に沿った幅の双方が、一定である。ここでは、均一コンデンサの読出電極と対向電極との間隔ｄが一定であり、均一コンデンサの読出電極１２ｄの幅が第１～第３周期コンデンサの読出電極の平均幅Ｗ_０に等しい例を説明する。この例では、水位がｈであるとき、均一コンデンサの浸水部分の面積Ｓ_０（ｈ）は、Ｗ_０×ｈで与えられる。 Next, the uniform capacitor will be described. In a uniform capacitor, both the distance between the read electrode and the counter electrode and the width along the direction orthogonal to the longitudinal direction of the read electrode are constant. Here, an example will be described in which the distance d between the read electrode of the uniform capacitor and the counter electrode is constant, and the width of the read electrode 12d of the uniform capacitor is equal to the average width _W0 of the read electrodes of the first to third period capacitors. .. In this example, when the water level is h, the area S ₀ (h) of the flooded portion of the uniform condenser is given by W ₀ × h.

従って、第１～第３周期コンデンサの読出電極１２ｄの浸水部分の各静電容量と、均一コンデンサの静電容量との差をとると、測定値として、以下の式（４ａ）～（４ｄ）が得られる。 Therefore, when the difference between each capacitance of the flooded portion of the read electrode 12d of the first to third period capacitors and the capacitance of the uniform capacitor is taken, the following equations (4a) to (4d) are taken as measured values. Is obtained.

上記式（４ａ）～（４ｃ）を水位ｈに対応する位相φで書き直すと、以下の式（５ａ）～（５ｄ）が得られる。 By rewriting the above equations (4a) to (4c) with the phase φ corresponding to the water level h, the following equations (5a) to (5d) are obtained.

ここで、Ｎ（Ｎは０以上の整数）は、周期Ｌの繰り返し回数である。繰り返し回数Ｎと位相φが得られれば、上記式（５ｄ）から、水位ｈがわかる。 Here, N (N is an integer of 0 or more) is the number of repetitions of the period L. If the number of repetitions N and the phase φ are obtained, the water level h can be known from the above equation (5d).

ここで、繰り返し回数Ｎは、均一コンデンサの静電容量から得られる。均一コンデンサの静電容量を、周期Ｌを基準として考える。第１～３周期コンデンサの１周期Ｌに対応する高さまで浸水しているときの、均一コンデンサの基準静電容量は、以下の式（６）で与えられる。 Here, the number of repetitions N is obtained from the capacitance of the uniform capacitor. Consider the capacitance of the uniform capacitor with reference to the period L. The reference capacitance of the uniform capacitor when it is submerged to a height corresponding to the 1st cycle L of the 1st to 3rd cycle capacitors is given by the following equation (6).

従って、以下の式（７）で与えられる均一コンデンサの静電容量を、上記式（６）で与えられる基準静電容量で割って整数部分をとれば、周期の繰り返し回数Ｎが算出される。 Therefore, if the capacitance of the uniform capacitor given by the following equation (7) is divided by the reference capacitance given by the above equation (6) to take an integer part, the number of cycle repetitions N is calculated.

位相φは、第１～第３周期コンデンサの静電容量を利用して得られる。初期位相が互いに異なる３つの周期コンデンサを用いることで、位相φが一意に決まる。 The phase φ is obtained by using the capacitance of the first to third period capacitors. The phase φ is uniquely determined by using three periodic capacitors having different initial phases.

ここでは、読出電極１２の幅が余弦関数状に変化する例を説明したが、三角関数に限定されない。図２を参照して、読出電極の他の構成例を説明する。図２（Ａ）及び（Ｂ）は、第１周期コンデンサの読出電極の他の構成例を説明するための模式図である。 Here, an example in which the width of the read electrode 12 changes in the shape of a cosine function has been described, but the present invention is not limited to trigonometric functions. Another configuration example of the read electrode will be described with reference to FIG. 2A and 2B are schematic views for explaining another configuration example of the read electrode of the first period capacitor.

電極の幅を与える周期関数は、余弦関数などの厳密な三角関数で無くてもよく、三角関数に近似する、折れ線状の関数（例えば、図２（Ａ）参照）や、階段状の関数（例えば、図２（Ｂ）参照）であってもよい。ここで、読出電極１１２ｘが、図２（Ａ）に示す折れ線状の関数である場合や、読出電極１１２ｙが、図２（Ｂ）に示す階段状の関数である場合、これらの関数の最大値と最小値の差が、余弦関数の振幅の２倍に対応する。 The periodic function that gives the width of the electrode does not have to be a strict trigonometric function such as a cosine function, and is a broken line function (see, for example, FIG. 2A) or a stepped function (see, for example, FIG. For example, FIG. 2B) may be used. Here, when the read electrode 112x is a polygonal line function shown in FIG. 2 (A), or when the read electrode 112y is a stepped function shown in FIG. 2 (B), the maximum value of these functions is used. The difference between and the minimum value corresponds to twice the amplitude of the cosine function.

図２（Ａ）に示す折れ線状の関数の１周期あたりの折れ曲がり回数は、任意好適に設定することができる。 The number of bends per cycle of the polygonal line-shaped function shown in FIG. 2A can be arbitrarily set arbitrarily.

また、図２（Ｂ）に示す階段状の関数のステップ幅は、任意好適に設定することができる。ただし、周期関数が階段状の関数の場合は、算出される位相の精度がこのステップ幅に依存する。従って、階段状の関数のステップ幅は、要求される位相精度に対応する大きさよりも小さくするのが良い。また、図２（Ｂ）では、階段状の関数を余弦関数に直接近似させた例を示しているが、図２（Ａ）に示す折れ線状の関数に近似させてもよい。 Further, the step width of the stepped function shown in FIG. 2B can be arbitrarily set arbitrarily. However, when the periodic function is a step-like function, the accuracy of the calculated phase depends on this step width. Therefore, the step width of the stepped function should be smaller than the size corresponding to the required phase accuracy. Further, although FIG. 2B shows an example in which the stepped function is directly approximated to the cosine function, it may be approximated to the polygonal line function shown in FIG. 2A.

なお、ここでは、周期コンデンサを構成する読出電極の幅が、周期関数状に変化する例を説明したがこれに限定されない。例えば、周期コンデンサの読出電極の幅を均一として、周期コンデンサの、読出電極と対向電極との間隔を周期関数状に変化する構成にしてもよい。ここで、読出電極及び対向電極は、例えば、銅箔やアルミ箔など導電性の材料の表面に絶縁被膜を形成して構成される。従って、絶縁被膜の厚みを周期関数状に変化させることで、読出電極と対向電極の間隔を周期関数状に変化させることができる。 Here, an example in which the width of the read electrode constituting the periodic capacitor changes in a periodic function is described, but the present invention is not limited to this. For example, the width of the read electrode of the periodic capacitor may be made uniform, and the distance between the read electrode and the counter electrode of the periodic capacitor may be changed in a periodic function. Here, the read electrode and the counter electrode are configured by forming an insulating film on the surface of a conductive material such as a copper foil or an aluminum foil. Therefore, by changing the thickness of the insulating film in a periodic function, the distance between the read electrode and the counter electrode can be changed in a periodic function.

また、ここでは、コンデンサが平行平板の電極で構成される例を説明したが、これに限定されない。最大値と最小値との差及び周期Ｌが互いに同じで、位相が互いに異なっている周期関数で表される、第１～第３周期コンデンサの静電容量と、第１～第３周期コンデンサの静電容量の平均値と等しい均一コンデンサの静電容量が得られれば、電極の構成は任意好適に設定できる。 Further, here, an example in which the capacitor is composed of electrodes of parallel plates has been described, but the present invention is not limited to this. The capacitance of the 1st to 3rd period capacitors and the capacitance of the 1st to 3rd period capacitors, which are represented by periodic functions in which the difference between the maximum value and the minimum value and the period L are the same but the phases are different from each other. If the capacitance of the uniform capacitor equal to the average value of the capacitance is obtained, the electrode configuration can be arbitrarily set.

（第１実施例）
図３を参照して、第１実施例の水位センサを説明する。図３は、第１実施例の水位センサを説明するための模式図である。 (First Example)
The water level sensor of the first embodiment will be described with reference to FIG. FIG. 3 is a schematic diagram for explaining the water level sensor of the first embodiment.

各電極はｙ軸が鉛直方向になるように配置される。すなわち、ｙ軸方向（長手方向）が高さ方向となる。またｘ軸に沿った辺のうち、低い位置に配置される辺のｙ座標を０とする。 Each electrode is arranged so that the y-axis is in the vertical direction. That is, the y-axis direction (longitudinal direction) is the height direction. Further, the y-coordinate of the side arranged at the lower position among the sides along the x-axis is set to 0.

この第１実施例の水位センサは、コンデンサ部１００、静電容量測定部２００及び演算部３００を備えて構成される。 The water level sensor of the first embodiment includes a condenser unit 100, a capacitance measuring unit 200, and a calculation unit 300.

第１実施例の水位センサでは、コンデンサ部１００は、第１～第３左コンデンサ１１
２、１２２、１３２及び第１～第３右コンデンサ１１４、１２４、１３４の合わせて６つのコンデンサを備えて構成される。静電容量測定部２００は、６つのコンデンサの静電容量を測定する機能を有していればよく、任意好適な従来公知のものを用いることができる。演算部３００は、静電容量測定部２００での測定結果に基づいて、水位を算出する。演算部３００は、所定のプログラムを実行可能な、例えば、マイクロコンピュータなどで構成される。演算部３００は、所定のプログラムを実行することにより各機能手段を実現する。各機能手段の動作については後述する。 In the water level sensor of the first embodiment, the condenser portion 100 is the first to third left condenser 11.
It is configured to include a total of six capacitors including 2, 122, 132 and the first to third right capacitors 114, 124, 134. The capacitance measuring unit 200 may have a function of measuring the capacitance of the six capacitors, and any suitable conventionally known capacitor can be used. The calculation unit 300 calculates the water level based on the measurement result of the capacitance measurement unit 200. The arithmetic unit 300 is composed of, for example, a microcomputer capable of executing a predetermined program. The arithmetic unit 300 realizes each functional means by executing a predetermined program. The operation of each functional means will be described later.

図３では、第１～第３左コンデンサ１１２、１２２、１３２及び第１～第３右コンデンサ１１４、１２４、１３４の合わせて６つのコンデンサを構成する電極対のそれぞれ一方の電極である読出電極を図示している。 In FIG. 3, a read electrode, which is one electrode of each of the electrode pairs constituting the total of six capacitors including the first to third left capacitors 112, 122, 132 and the first to third right capacitors 114, 124, 134, is shown. It is shown in the figure.

第１左コンデンサ１１２を構成する第１左読出電極は、ｙ軸に沿った辺のうち、一方の側（ここでは、左側）の辺が直線状であり、他方の側（ここでは、右側）の辺が周期関数状である。周期関数は正弦関数及び余弦関数など任意好適な関数にすることができるが、ここでは、周期関数が余弦関数であり、各辺が余弦曲線で表される例を説明する。第１左読出電極の右側の辺の余弦曲線が、周期Ｌ及び振幅Ｒの余弦曲線であり、第１左読出電極の平均幅がＷ_０／２であるとき、第１左読出電極の幅Ｗ_１Ｌ（ｙ）は以下の式（８ａ）で与えられる。 The first left read electrode constituting the first left capacitor 112 has a linear side on one side (here, the left side) of the sides along the y-axis, and the other side (here, the right side). The side of is a periodic function. The periodic function can be any suitable function such as a sine function and a cosine function, but here, an example in which the periodic function is a cosine function and each side is represented by a cosine curve will be described. When the chord curve on the right side of the first left read electrode is a chord curve having a period L and an amplitude R, and the mean width of the first left read electrode is W _0/2 , the width W of the first left read electrode is W. ₁ L (y) is given by the following equation (8a).

また、第２及び第３左コンデンサ１２２及び１３２を構成する第２及び第３左読出電極は、第１左読出電極と同様に、左側の辺が直線状であり、右側の辺が余弦曲線状である。第１～第３左読出電極の右側の辺は、同じ周期Ｌかつ同じ振幅Ｒであり、互いに初期位相が１２０度（２π／３）ずれている余弦曲線で表される。また、第１～第３左読出電極の平均幅は互いに同じ幅であり、Ｗ_０／２である。この場合、第２及び第３左読出電極の幅Ｗ_２Ｌ（ｙ）及びＷ_３Ｌ（ｙ）は、以下の式（８ｂ）及び（８ｃ）で与えられる。 Further, the second and third left read electrodes constituting the second and third left capacitors 122 and 132 have a linear left side and a cosine curve on the right side, similarly to the first left read electrode. Is. The right side of the first to third left read electrodes has the same period L and the same amplitude R, and is represented by a cosine curve whose initial phase is 120 degrees (2π / 3) out of phase with each other. Further, the average widths of the first to third left read electrodes are the same as each other, and are W _0/2 . In this case, the widths W ₂ L (y) and W ₃ L (y) of the second and third left read electrodes are given by the following equations (8b) and (8c).

一方、第１右コンデンサ１１４を構成する、第１右読出電極は、ｙ軸に沿った辺のうち、一方の側（ここでは、左側）の辺が余弦曲線状であり、他方の側（ここでは、右側）の辺が直線状である。第１左読出電極の幅Ｗ_１Ｌ（ｙ）と第１右読出電極の幅Ｗ_１Ｒ（ｙ）の和は、一定であり、第１右読出電極の平均幅は、第１左読出電極の平均幅と等しくＷ_０／２である。 On the other hand, in the first right read electrode constituting the first right capacitor 114, one side (here, the left side) of the sides along the y-axis has a cosine curve, and the other side (here). Then, the side on the right side) is linear. The sum of the width W ₁ L (y) of the first left read electrode and the width W ₁ R (y) of the first right read electrode is constant, and the average width of the first right read electrode is the first left read electrode. W _0/2 , which is equal to the mean width of.

第２及び第３右コンデンサ１２４及び１３４を構成する第２及び第３右読出電極は、第１右読出電極と同様に、左側の辺が余弦曲線状であり、右側の辺が直線状である。第２左読出電極の幅Ｗ_２Ｌ（ｙ）と第２右読出電極の幅Ｗ_２Ｒ（ｙ）の和、及び、第３左読出電極の幅Ｗ_３Ｌ（ｙ）と第３右読出電極の幅Ｗ_３Ｒ（ｙ）の和は、いずれも一定である。第２及び第３右読出電極１２４ａ及び１３４ａの平均幅は、Ｗ_０／２である。このとき、第１～第３右読出電極の幅Ｗ_１Ｒ（ｙ）～Ｗ_３Ｒ（ｙ）は、以下の式（９ａ）～（９ｃ）で与えられる。 Like the first right read electrode, the second and third right read electrodes constituting the second and third right capacitors 124 and 134 have a cosine curve on the left side and a linear shape on the right side. .. The sum of the width W ₂ L (y) of the second left read electrode and the width W ₂ R (y) of the second right read electrode, and the width W ₃ L (y) of the third left read electrode and the third right read. The sum of the electrode widths W ₃ R (y) is constant. The average width of the second and third right read electrodes 124a and 134a is W _0/2 . At this time, the widths W ₁ R (y) to W ₃ R (y) of the first to third right read electrodes are given by the following equations (9a) to (9c).

水位がｈであるとき、浸水している、第１～第３左読出電極の面積Ｓ_１Ｌ（ｈ）～Ｓ_３Ｌ（ｈ）及び第１～第３右読出電極の面積Ｓ_１Ｒ（ｈ）～Ｓ_３Ｒ（ｈ）は、以下の式（１０ａ）～（１０ｆ）で与えられる。 When the water level is h, the area of the first to third left read electrodes S ₁ L (h) to S ₃ L (h) and the area of the first to third right read electrodes S ₁ R ( h) to S ₃ R (h) are given by the following equations (10a) to (10f).

静電容量取得部２００は、コンデンサ部１００の各コンデンサの静電容量を取得する。浸水していない部分の静電容量を無視すると、第１～第３左コンデンサ１１２、１２２及び１３２並びに第１右コンデンサ１１４、１２４及び１３４の静電容量の測定値Ｄ_１Ｌ（ｈ）～Ｄ_３Ｌ（ｈ）及びＤ_１Ｒ（ｈ）～Ｄ_３Ｒ（ｈ）は、それぞれ、以下の式（１１ａ）～（１１ｆ）で与えられる。静電容量取得部２００で取得された静電容量の測定値Ｄ_１Ｌ（ｈ）～Ｄ_３Ｌ（ｈ）及びＤ_１Ｒ（ｈ）～Ｄ_３Ｒ（ｈ）は、演算部３００に送られる。 The capacitance acquisition unit 200 acquires the capacitance of each capacitor of the capacitor unit 100. Ignoring the capacitance of the non-flooded part, the measured values of the capacitance of the first to third left capacitors 112, 122 and 132 and the first right capacitors 114, 124 and 134 D ₁ L (h) to D ₃ L (h) and D ₁ R (h) to D ₃ R (h) are given by the following equations (11a) to (11f), respectively. The measured values of capacitance D ₁ L (h) to D ₃ L (h) and D ₁ R (h) to D ₃ R (h) acquired by the capacitance acquisition unit 200 are sent to the calculation unit 300. Be done.

演算部３００が備える、静電容量取得手段３０２は、第１～第３左コンデンサ１１２、１２２及び１３２並びに第１右コンデンサ１１４、１２４及び１３４の静電容量の測定値、Ｄ_１Ｌ（ｈ）～Ｄ_３Ｌ（ｈ）及びＤ_１Ｒ（ｈ）～Ｄ_３Ｒ（ｈ）から第１～第３周期コンデンサ１１０，１２０及び１３０の静電容量の測定値Ｄ_１´（ｈ）～Ｄ_３´（ｈ）を取得する。具体的には、以下の式（１２ａ）～（１２ｄ）で表されるように、第１左コンデンサ１１２の静電容量の測定値から第１右コンデンサ１１４の静電容量の測定値を減算したものを第１周期コンデンサ１１０の静電容量の測定値Ｄ_１´（ｈ）とし、第２左コンデンサ１２２の静電容量の測定値から第２右コンデンサ１２４の静電容量の測定値を減算したものを第２周期コンデンサ１２０の静電容量の測定値Ｄ_２´（ｈ）とし、第３左コンデンサ１３２の静電容量の測定値から第３右コンデンサ１３４の静電容量の測定値を減算したものを第３周期コンデンサ１３０の静電容量の測定値Ｄ_３´（ｈ）とする。 The capacitance acquisition means 302 included in the calculation unit 300 includes measured values of the capacitances of the first to third left capacitors 112, 122 and 132 and the first right capacitors 114, 124 and 134, D ₁ L (h). ~ D ₃ L (h) and D ₁ R (h) ~ D ₃ R (h) to the measured values of the capacitances of the first to third period capacitors 110, 120 and 130 D ₁ '(h) ~ D ₃ ´ (h) is acquired. Specifically, as represented by the following equations (12a) to (12d), the measured value of the capacitance of the first right capacitor 114 is subtracted from the measured value of the capacitance of the first left capacitor 112. Let the measured value of the capacitance of the first cycle capacitor 110 be D ₁ '(h), and the measured value of the capacitance of the second right capacitor 124 was subtracted from the measured value of the capacitance of the second left capacitor 122. Let the measured value of the capacitance of the second period capacitor 120 be D ₂ '(h), and the measured value of the capacitance of the third right capacitor 134 was subtracted from the measured value of the capacitance of the third left capacitor 132. Let this be the measured value D ₃ '(h) of the capacitance of the third period capacitor 130.

ここで、上記式（１２ｂ）及び（１２ｃ）で与えられる、第２及び第３周期コンデンサ１２０及び１３０の静電容量の測定値Ｄ_２´（ｈ）及びＤ_３´（ｈ）の最後の項は、いわゆる測定値のずれである。この測定値のずれの成分を除去すると、第１～第３周期コンデンサの静電容量の測定値は、以下の式（１３ａ）～（１３ｄ）で与えられる。 Here, the last term of the measured values D ₂ ′ (h) and D ₃ ′ (h) of the capacitances of the second and third period capacitors 120 and 130 given by the above equations (12b) and (12c). Is the so-called deviation of the measured value. When the component of the deviation of the measured values is removed, the measured values of the capacitance of the first to third period capacitors are given by the following equations (13a) to (13d).

ここで、Ｎは周期Ｌの繰り返し回数を表す。なお、測定値のずれの補正については後述
する。 Here, N represents the number of repetitions of the period L. The correction of the deviation of the measured value will be described later.

また、第１左コンデンサ１１２の静電容量の測定値と第１右コンデンサ１１４の静電容量の測定値を加算したものを均一コンデンサの静電容量とする。なお、上述の通り、第１左読出電極の幅Ｗ_１Ｌ（ｙ）と第１右読出電極の幅Ｗ_１Ｒ（ｙ）の和、第２左読出電極の幅Ｗ_２Ｌ（ｙ）と第２右読出電極の幅Ｗ_２Ｒ（ｙ）の和、及び、第３左読出電極の幅Ｗ_３Ｌ（ｙ）と第３右読出電極の幅Ｗ_３Ｒ（ｙ）の和は、いずれも一定でＷ_０である。従って、均一コンデンサの静電容量は、第１左コンデンサ１１２の静電容量の測定値と第１右コンデンサ１１４の静電容量の測定値を加算したものに限定されず、第２左コンデンサ１２２の静電容量の測定値と第２右コンデンサ１２４の静電容量の測定値を加算したものや、第３左コンデンサ１３２の静電容量の測定値と第３右コンデンサ１３４の静電容量の測定値を加算したものとしてもよい。 Further, the sum of the measured value of the capacitance of the first left capacitor 112 and the measured value of the capacitance of the first right capacitor 114 is taken as the capacitance of the uniform capacitor. As described above, the sum of the width W ₁ L (y) of the first left read electrode and the width W ₁ R (y) of the first right read electrode, and the width W ₂ L (y) of the second left read electrode. Whichever is the sum of the width W ₂ R (y) of the second right read electrode and the width W ₃ L (y) of the third left read electrode and the width W ₃ R (y) of the third right read electrode? Is constant and W ₀ . Therefore, the capacitance of the uniform capacitor is not limited to the sum of the measured value of the capacitance of the first left capacitor 112 and the measured value of the capacitance of the first right capacitor 114, and the capacitance of the second left capacitor 122 is not limited. The value obtained by adding the measured value of the capacitance and the measured value of the capacitance of the second right capacitor 124, the measured value of the capacitance of the third left capacitor 132 and the measured value of the capacitance of the third right capacitor 134. May be added.

図４は、Ｄ_１（φ）、Ｄ_２（φ）及びＤ_３（φ）を示す図である。縦軸に長手方向の軸（ｙ軸）をとって示し、横軸にＤ_１（φ）、Ｄ_２（φ）及びＤ_３（φ）を任意単位でとって示している。 FIG. 4 is a diagram showing D ₁ (φ), D ₂ (φ) and D ₃ (φ). The vertical axis is the longitudinal axis (y-axis), and the horizontal axis is D ₁ (φ), D ₂ (φ) and D ₃ (φ) in arbitrary units.

Ｄ_１（ｈ）、Ｄ_２（ｈ）、Ｄ_３（ｈ）の和は０となる。また、Ｄ_１（ｈ）、Ｄ_２（ｈ）、Ｄ_３（ｈ）の２乗の和は（Ｋ×２Ｒ）^２×３／２となる。従って、Ｄ_１（ｈ）、Ｄ_２（ｈ）、Ｄ_３（ｈ）から（Ｋ×２Ｒ）が得られる。Ｒは、電極の設計で決まる値であるので、（Ｋ×２Ｒ）が得られれば、Ｋが求められる。また、Ｋが求められれば、上記式
（１２ｄ）からεｒ（ｗａｔｅｒ）が計算される。 The sum of D ₁ (h), D ₂ (h), and D ₃ (h) is 0. Further, the sum of the squares of D ₁ (h), D ₂ (h), and D ₃ (h) is (K × 2R) ² × 3/2. Therefore, (K × 2R) can be obtained from D ₁ (h), D ₂ (h), and D ₃ (h). Since R is a value determined by the design of the electrode, if (K × 2R) is obtained, K can be obtained. If K is obtained, εr (water) is calculated from the above equation (12d).

演算部３００が備える繰り返し回数取得手段３０６は、位相取得手段３０４が取得した位相φが何周期目にあるか、すなわち周期の繰り返し回数Ｎを算出する。まず、第１左コンデンサ１１２と第１右コンデンサ１１４の測定値の和（Ｄ_１Ｌ（ｈ）＋Ｄ_１Ｒ（ｈ）＝Ｗ_０ｈ×εｒ（ｗａｔｅｒ）／ｄ）を計算する。次に、Ｄ_０（ｈ）をＷ_０Ｌ×εｒ（ｗａｔｅｒ）／ｄで除算すれば、ｈが何周期目にあるか、すなわち周期の繰り返し回数Ｎが算出できる。 The repetition number acquisition means 306 provided in the calculation unit 300 calculates the cycle number in which the phase φ acquired by the phase acquisition means 304 is, that is, the cycle repetition number N. First, the sum of the measured values of the first left capacitor 112 and the first right capacitor 114 (D ₁ L (h) + D ₁ R (h) = W ₀ h × εr (water) / d) is calculated. Next, by dividing D ₀ (h) by W ₀ L × εr (water) / d, it is possible to calculate the cycle number of h, that is, the number of cycle repetitions N.

さらに、以下の関係式（１４ａ）～（１４ｃ）から、φが一義的に定まる。 Further, φ is uniquely determined from the following relational expressions (14a) to (14c).

演算部３００が備える位相取得手段３０４は、Ｄ_１（ｈ）、Ｄ_２（ｈ）、Ｄ_３（ｈ）から上記の式（１４ａ）～（１４ｃ）を用いて位相φを求める。 The phase acquisition means 304 included in the calculation unit 300 obtains the phase φ from D ₁ (h), D ₂ (h), and D ₃ (h) using the above equations (14a) to (14c).

演算部３００が備える水位取得手段３０８は、位相取得手段が取得した位相φと、繰り返し回数取得手段が取得した繰り返し回数Ｎを用いて、上記の式（１３ｄ）を用いて、水位ｈを算出する。 The water level acquisition means 308 included in the calculation unit 300 calculates the water level h using the above equation (13d) using the phase φ acquired by the phase acquisition means and the repetition number N acquired by the repetition count acquisition means. ..

この発明の水位センサでは、電極構造が有する周期Ｌの周期性を用いて、水位ｈの大まかな位置を求め、その後、位相からその周期内での位置を測定する。この水位ｈの大まかな位置は、測定対象の誘電率が変化したとしても、正確な水位を求める必要はないので、問題にはならないことが多い。 In the water level sensor of the present invention, the approximate position of the water level h is obtained by using the periodicity of the period L of the electrode structure, and then the position within the period is measured from the phase. The rough position of the water level h is often not a problem even if the dielectric constant of the measurement target changes, because it is not necessary to obtain an accurate water level.

周期の繰り返し回数Ｎを求めた後、位相φを用いて測定するので、その１周期内での正確な位置を算出することができる。また、互いに１２０度位相がずれた３つの測定値を用いることで、誘電率に依存せずに位相φを求めることができる。したがって、基準電極を用いる必要はない。また、１つの水位に対する測定データから水位を求めることができる。 Since the measurement is performed using the phase φ after the number of repetitions N of the cycle is obtained, the accurate position within the one cycle can be calculated. Further, by using three measured values that are 120 degrees out of phase with each other, the phase φ can be obtained independently of the dielectric constant. Therefore, it is not necessary to use a reference electrode. Further, the water level can be obtained from the measurement data for one water level.

また、Ｄ_１（ｈ）、Ｄ_２（ｈ）、Ｄ_３（ｈ）の和は０となる。従って、例えば、断線などにより第３周期コンデンサの測定値が得られない場合でも、均一コンデンサの測定値から第１周期コンデンサ及び第２周期コンデンサの測定値を減算することで、第３周期コンデンサの測定値を得ることができる。 Further, the sum of D ₁ (h), D ₂ (h), and D ₃ (h) is 0. Therefore, for example, even if the measured value of the 3rd period capacitor cannot be obtained due to disconnection, the measured values of the 1st period capacitor and the 2nd period capacitor can be subtracted from the measured value of the uniform capacitor to obtain the measured value of the 3rd period capacitor. The measured value can be obtained.

なお、６対の電極対を用いる場合、第１～第３周期コンデンサの測定値を得る際に、左コンデンサと右コンデンサの測定値の差分を取るため、振幅が２倍となり、ノイズが相殺される効果がある。 When 6 pairs of electrodes are used, when the measured values of the 1st to 3rd period capacitors are obtained, the difference between the measured values of the left capacitor and the right capacitor is taken, so that the amplitude is doubled and the noise is offset. Has the effect.

また、製造の際には、幅Ｗ_０の矩形の金属板から、右読出電極を切り出した残りを左読出電極として用いることができるので、製造工程を過剰に複雑にすることもない。 Further, in the case of manufacturing, the remainder of the right read electrode cut out from the rectangular metal plate having a width W ₀ can be used as the left read electrode, so that the manufacturing process is not excessively complicated.

測定値のずれが補正されていない場合、上記式（８ａ）及び（８ｂ）に示すように、水位ｈが０において、第２周期コンデンサ１２０及び第３周期コンデンサ１３０の測定データＤ_２´（０）が及びＤ_３´（０）が０となり、図５に示すように、測定データの平均が０とならない。図５は測定値のずれの影響を示す模式図である。第１実施例の水位センサでは、上記式（１０ａ）～（１０ｃ）を用いて、第１～第３周期コンデンサ１１０、１２０及び１３０の測定データから位相φを求めるが、測定値のずれがあると、正しく位相φを求めることができない。このため測定値のずれを補正する必要がある。 When the deviation of the measured value is not corrected, as shown in the above equations (8a) and (8b), the measurement data D ₂ ′ (0) of the second period capacitor 120 and the third period capacitor 130 at the water level h of 0. ) And D ₃ '(0) become 0, and as shown in FIG. 5, the average of the measurement data does not become 0. FIG. 5 is a schematic diagram showing the influence of the deviation of the measured values. In the water level sensor of the first embodiment, the phase φ is obtained from the measurement data of the first to third period capacitors 110, 120 and 130 using the above equations (10a) to (10c), but there is a deviation in the measured values. And, the phase φ cannot be obtained correctly. Therefore, it is necessary to correct the deviation of the measured value.

測定値のずれの補正は、測定データから演算部３００での処理により行うこともできる。あるいは、補正電極を設けて補正することもできる。 The correction of the deviation of the measured value can also be performed by processing the measurement data in the calculation unit 300. Alternatively, correction can be performed by providing a correction electrode.

図３に示す第１実施例では、第２周期コンデンサ１２０の測定値のずれを補正するために、第２左コンデンサ１２２の読出電極に、面積がＬ／２×Ｒ×ｓｉｎ（２π／３）である第２補正電極１２６を設ける。また、第３周期コンデンサ１３０の測定値のずれを補正するために、第３右コンデンサ１３４の読出電極に、面積がＬ／２π×Ｒ×ｓｉｎ（２π／３）である第３補正電極１３６を設ける。 In the first embodiment shown in FIG. 3, in order to correct the deviation of the measured value of the second period capacitor 120, the read electrode of the second left capacitor 122 has an area of L / 2 × R × sin (2π / 3). The second correction electrode 126 is provided. Further, in order to correct the deviation of the measured value of the third period capacitor 130, a third correction electrode 136 having an area of L / 2π × R × sin (2π / 3) is attached to the read electrode of the third right capacitor 134. prepare.

この第２及び第３補正電極１２６及び１３６を設けることで、ｈ＝０における、第２周期コンデンサ及び第３周期コンデンサの測定データＤ_２（０）が及びＤ_３（０）がそれぞれ、Ｋ×２Ｒ×ｓｉｎ（２π／３）及びＫ×２Ｒ×ｓｉｎ（－２π／３）となるので、位相φを正しく求めることができる。 By providing the second and third correction electrodes 126 and 136, the measurement data D ₂ (0) and D ₃ (0) of the second period capacitor and the third period capacitor at h = 0 are K ×, respectively. Since 2R × sin (2π / 3) and K × 2R × sin (-2π / 3), the phase φ can be obtained correctly.

（第２実施例）
図６を参照して、第２実施例の水位センサを説明する。図６は、第２実施例の水位センサを説明するための模式図である。 (Second Example)
The water level sensor of the second embodiment will be described with reference to FIG. FIG. 6 is a schematic diagram for explaining the water level sensor of the second embodiment.

第２実施例の水位センサは、コンデンサ部の構造が、第１実施例の水位センサと異なっている。他の構成は、第１実施例と同様なので、重複する説明を省略する。 The structure of the condenser portion of the water level sensor of the second embodiment is different from that of the water level sensor of the first embodiment. Since the other configurations are the same as those in the first embodiment, duplicate description will be omitted.

第２実施例の水位センサでは、コンデンサ部１０１は、第１～第３コンデンサ１１１、１２１及び１３１の３つのコンデンサを備えて構成される。図６は、第１～第３コンデンサ１１１、１２１及び１３１の合わせて３つのコンデンサを構成する電極対のそれぞれ一方の電極である読出電極を図示している。 In the water level sensor of the second embodiment, the condenser portion 101 includes three condensers of the first to third condensers 111, 121 and 131. FIG. 6 illustrates a read electrode, which is one of the electrodes of the electrode pair constituting the three capacitors including the first to third capacitors 111, 121, and 131.

第１コンデンサ１１１を構成する第１読出電極は、ｙ軸に沿った辺のうち、一方の側（ここでは、左側）の辺が直線状であり、他方の側（ここでは、右側）の辺が周期関数状である。周期関数は正弦関数及び余弦関数など任意好適な関数にすることができるが、ここでは、周期関数が余弦関数であり、辺が余弦曲線で表される例を説明する。すなわち、第１読出電極の右側の辺の余弦曲線が、周期Ｌ及び振幅Ｒの余弦曲線であり、第１読出電極の平均幅がＷｏであるとする。 The first read electrode constituting the first capacitor 111 has a linear side on one side (here, the left side) and a side on the other side (here, the right side) of the sides along the y-axis. Is a periodic function. The periodic function can be any suitable function such as a sine function and a cosine function, but here, an example in which the periodic function is a cosine function and the sides are represented by a cosine curve will be described. That is, it is assumed that the cosine curve on the right side of the first read electrode is the cosine curve having the period L and the amplitude R, and the average width of the first read electrode is Wo.

第３コンデンサ１３１を構成する第３読出電極は、ｙ軸に沿った辺のうち、一方の側（ここでは、右側）の辺が直線状であり、他方の側（ここでは、左）の辺が周期関数状である。ここでは、第１読出電極と同様に、第３読出電極の周期関数が余弦関数であり、辺が余弦曲線で表されるものとする。すなわち、第３読出電極の左側の辺の余弦曲線が、周期Ｌ及び振幅Ｒの余弦曲線であり、第３読出電極の平均幅がＷｏであるとする。 The third read electrode constituting the third capacitor 131 has a linear side on one side (here, the right side) and a side on the other side (here, the left) of the sides along the y-axis. Is a periodic function. Here, it is assumed that the periodic function of the third read electrode is a cosine function and the sides are represented by a cosine curve, as in the case of the first read electrode. That is, it is assumed that the cosine curve on the left side of the third read electrode is the cosine curve having the period L and the amplitude R, and the average width of the third read electrode is Wo.

第２コンデンサ１２１を構成する第２読出電極は、ｙ軸に沿った辺の左側及び右側の両者の辺が周期関数状である。ここでは、第１及び第３読出電極と同様に、周期関数が余弦関数であり、辺が余弦曲線で表される例を説明する。すなわち、第２読出電極の両側の辺の余弦曲線が、周期Ｌ及び振幅Ｒの余弦曲線であり、第２読出電極の平均幅がＷｏであるとする。 The second read electrode constituting the second capacitor 121 has a periodic function on both the left and right sides of the side along the y-axis. Here, an example in which the periodic function is a cosine function and the sides are represented by a cosine curve will be described, as in the case of the first and third read electrodes. That is, it is assumed that the cosine curves on both sides of the second read electrode are cosine curves having a period L and an amplitude R, and the average width of the second read electrode is Wo.

このとき、第１～第３コンデンサ１１１、１２１及び１３１は、それぞれ、上記第１～第３周期コンデンサとなる。また、第１～第３読出電極の幅Ｗ_１（ｙ）～Ｗ_３（ｙ）は、以下の式（１５ａ）～（１５ｃ）で与えられる。 At this time, the first to third capacitors 111, 121, and 131 are the first to third period capacitors, respectively. Further, the widths W ₁ (y) to W ₃ (y) of the first to third read electrodes are given by the following equations (15a) to (15c).

また、第１～第３読出電極の幅の和（Ｗ_１（ｙ）＋Ｗ_２（ｙ）＋Ｗ_３（ｙ））は、一定値である３Ｗ_０／２となる。したがって、第１～第３周期コンデンサを並列接続したものを一体として、均一コンデンサとすることができる。この場合、第１～第３コンデンサの静電容量の和の１／３が、均一コンデンサの静電容量になる。 Further, the sum of the widths of the first to third read electrodes (W ₁ (y) + W ₂ (y) + W ₃ (y)) is 3W _0/2 , which is a constant value. Therefore, a capacitor in which first to third period capacitors are connected in parallel can be integrated into a uniform capacitor. In this case, 1/3 of the sum of the capacitances of the first to third capacitors is the capacitance of the uniform capacitor.

この第２実施例の構成によれば、３つのコンデンサで、第１～３周期コンデンサ及び均一コンデンサを実現できるので、第１実施例の水位センサと比べて、コンパクトに構成することができる。 According to the configuration of the second embodiment, the first to third period capacitors and the uniform capacitor can be realized with three capacitors, so that the configuration can be made more compact than the water level sensor of the first embodiment.

（他の構成例１）
第１実施例の水位センサは、６のコンデンサ（６対の電極対）を備え、第２実施例の水位センサは、３のコンデンサ（３対の電極対）を備える。しかし、この発明の水位センサはこれに限定されない。 (Other Configuration Example 1)
The water level sensor of the first embodiment includes 6 capacitors (6 pairs of electrode pairs), and the water level sensor of the second embodiment includes 3 capacitors (3 pairs of electrode pairs). However, the water level sensor of the present invention is not limited to this.

第１～３周期コンデンサと、均一コンデンサの４つのコンデンサを、それぞれ独立した電極対、すなわち、４対の電極対で構成してもよい。また、第１～３周期コンデンサと、均一コンデンサの４つのコンデンサの各読出電極を、それぞれ１つの電極で構成してもよいし、２以上の電極を組み合わせて構成してもよい。 The first to third cycle capacitors and the four capacitors of the uniform capacitor may be composed of independent electrode pairs, that is, four pairs of electrodes. Further, each read electrode of the first to third cycle capacitors and the four capacitors of the uniform capacitor may be configured by one electrode each, or may be configured by combining two or more electrodes.

（他の構成例２）
上述した、第１実施例及び第２実施例の水位センサでは、周期の繰り返し回数Ｎを算出する際に、隣接する周期との境界付近において、繰り返し回数Ｎを誤って算出してしまう可能性がある。 (Other Configuration Example 2)
In the water level sensors of the first embodiment and the second embodiment described above, when calculating the cycle repetition number N, there is a possibility that the repetition count N is erroneously calculated near the boundary with the adjacent cycle. be.

そこで、水位センサを２つ用意し、第１の水位センサの周期がＬ１であるとき、第２の水位センサの周期を、第１の水位センサの周期Ｌ１とは異なるＬ２とするのがよい。このように周期Ｌが異なる２つの水位センサを用いることで、繰り返し回数Ｎの算出の誤りを減らすことができる。 Therefore, it is preferable to prepare two water level sensors and set the cycle of the second water level sensor to L2 different from the cycle L1 of the first water level sensor when the cycle of the first water level sensor is L1. By using the two water level sensors having different cycles L in this way, it is possible to reduce the error in calculating the number of repetitions N.

（他の構成例３）
ここでは、静電容量測定装置の一実施形態として、水位センサの例を説明したが、これに限定されない。この発明の静電容量測定装置は、比誘電率εｒが１よりも十分大きければ、水の高さだけでなく、有機溶媒、液体燃料、液化ガスなどの液体の高さを測定できる。例えば、密閉されていて視認が容易でない容器内の液体の高さ（液面の位置）などの測定に期待される。また、配合飼料などの、粉体、粒体の高さも測定可能である。この場合、比誘電率εｒが１よりも十分大きければ、測定前に液体、粉体、粒体の比誘電率εｒの正確な数値を得ておく必要はない。 (Other Configuration Example 3)
Here, an example of a water level sensor has been described as an embodiment of the capacitance measuring device, but the present invention is not limited to this. The capacitance measuring device of the present invention can measure not only the height of water but also the height of liquids such as organic solvents, liquid fuels, and liquefied gases if the relative permittivity εr is sufficiently larger than 1. For example, it is expected to measure the height (position of the liquid level) of the liquid in the container which is sealed and not easy to see. It is also possible to measure the height of powders and granules of compound feeds. In this case, if the relative permittivity εr is sufficiently larger than 1, it is not necessary to obtain an accurate value of the relative permittivity εr of the liquid, powder, or granule before the measurement.

また、電極間の物質の比誘電率εｒの測定も可能である。例えば、土壌に含まれる水分量による比誘電率εｒの違いから、土壌に含まれる水分量の測定も可能となる。 It is also possible to measure the relative permittivity εr of a substance between electrodes. For example, the difference in the relative permittivity εr depending on the amount of water contained in the soil makes it possible to measure the amount of water contained in the soil.

（他の構成例４）
また、ここでは、静電容量測定装置が、第１～第３周期コンデンサを備える例を説明したが、周期コンデンサの数は、３に限定されない。周期コンデンサの数Ｐは、３以上の整数にすることができる。 (Other Configuration Example 4)
Further, here, an example in which the capacitance measuring device includes the first to third periodic capacitors has been described, but the number of periodic capacitors is not limited to three. The number P of periodic capacitors can be an integer of 3 or more.

第１実施例と同様の構成の水位センサが、第１～第Ｐ周期コンデンサを備える場合の例を説明する。上記式（１３ａ）～（１３ｃ）から、第ｋ（ｋは１以上Ｐ以下の整数）周期コンデンサの静電容量の測定値は、以下の式（１６ａ）で与えられる。また、このとき、
以下の式（１６ｂ）及び（１６ｃ）の関係がある。 An example will be described in which the water level sensor having the same configuration as that of the first embodiment includes the first to P period capacitors. From the above equations (13a) to (13c), the measured value of the capacitance of the kth (k is an integer of 1 or more and P or less) periodic capacitor is given by the following equation (16a). Also, at this time
There is a relationship between the following equations (16b) and (16c).

従って、上記式（１６ｃ）から、Ｋを得ることができ、さらに、上記式（４ｄ）から、εｒが得られる。さらに、第ｋ周期コンデンサの静電容量の測定値Ｄ_ｋ（φ）のうち、初期位相の差が１８０度（＝π）でない２つの測定値から、位相φを一意に求めることができる。 Therefore, K can be obtained from the above formula (16c), and εr can be further obtained from the above formula (4d). Further, of the measured values D _k (φ) of the capacitance of the k-period capacitor, the phase φ can be uniquely obtained from the two measured values whose initial phase difference is not 180 degrees (= π).

なお、Ｐが大きくなると、周期コンデンサの数が増えるため、コンデンサ部が大きくなる可能性がある。従って、Ｐは３以上であり、かつ、より小さい値として、３や４にするのが好ましい。 As P becomes larger, the number of periodic capacitors increases, so that the capacitor portion may become larger. Therefore, it is preferable that P is 3 or more and is set to 3 or 4 as a smaller value.

ここで、Ｐが４のとき、第１～第４周期コンデンサの静電容量の測定値Ｄ_ｋ（φ）は、以下の式（１７ａ）～（１７ｄ）で与えられる。 Here, when P is 4, the measured value D _k (φ) of the capacitance of the 1st to 4th period capacitors is given by the following equations (17a) to (17d).

上記式（１７ａ）～（１７ｄ）で示されるように、Ｄ_３（φ）＝－Ｄ_１（φ）及びＤ_４（φ）＝－Ｄ_２（φ）の関係がある。 As shown by the above equations (17a) to (17d), there is a relationship of D ₃ (φ) = −D ₁ (φ) and D ₄ (φ) = −D ₂ (φ).

この場合の構成例を図７を参照して説明する。図７は、第３実施例の水位センサを説明するための模式図である。第３実施例の水位センサは、第１～第２左コンデンサ１１７及び１２７並びに第１～第２右コンデンサ１１９及び１２９の合わせて４つのコンデンサを備える点が、第１実施例の水位センサと異なっている。第１実施例の水位センサと重複する構成については、説明を省略する場合がある。 A configuration example in this case will be described with reference to FIG. 7. FIG. 7 is a schematic diagram for explaining the water level sensor of the third embodiment. The water level sensor of the third embodiment is different from the water level sensor of the first embodiment in that it includes a total of four capacitors, the first and second left capacitors 117 and 127 and the first and second right capacitors 119 and 129. ing. The description of the configuration overlapping with the water level sensor of the first embodiment may be omitted.

第３実施例の水位センサでは、第１左コンデンサ１１７を構成する第１左読出電極の右側の辺と、第２左コンデンサ１２７を構成する第２左読出し電極の右側の辺は、いずれも周期Ｌ及び振幅Ｒの余弦曲線で表され、位相がπ／２ずれている。 In the water level sensor of the third embodiment, the right side of the first left read electrode constituting the first left capacitor 117 and the right side of the second left read electrode constituting the second left capacitor 127 are both periodic periods. It is represented by a chord curve of L and amplitude R, and is out of phase by π / 2.

従って、第１左コンデンサ１１７と第１右コンデンサ１１９の静電容量の測定値の差から上記式（１７ａ）で与えられるＤ_１（φ）と、上記式（１７ｃ）で与えられるＤ_３（φ）が得られる。また、第２左コンデンサ１２７と第２右コンデンサ１２９の静電容量の測定値の差から上記式（１７ｂ）で与えられるＤ_２（φ）と、上記式（１７ｄ）で与えられるＤ_４（φ）が得られる。Ｄ_１（φ）～Ｄ_４（φ）が得られた後の処理は、第１実施例の水位センサと同様なので説明を省略する。 Therefore, D ₁ (φ) given by the above equation (17a) and D ₃ (φ) given by the above equation (17c) from the difference in the measured values of the capacitances of the first left capacitor 117 and the first right capacitor 119. ) Is obtained. Further, D ₂ (φ) given by the above equation (17b) and D ₄ (φ) given by the above equation (17d) from the difference in the measured values of the capacitances of the second left capacitor 127 and the second right capacitor 129. ) Is obtained. Since the processing after obtaining D ₁ (φ) to D ₄ (φ) is the same as that of the water level sensor of the first embodiment, the description thereof will be omitted.

１２、１２ａ、１２ｂ、１２ｃ、１１２ｘ、１１２ｙ読出電極
１４対向電極
１００、１０１、１０２コンデンサ部
１１０、１２０、１３０電極対
１１１、１２１、１３１コンデンサ
１１２、１１７、１２２、１２７、１３２左コンデンサ
１１４、１１９、１２４、１２９、１３４右コンデンサ
２００静電容量取得部
３００演算部
３０２静電容量取得手段
３０４位相取得手段
３０６繰り返し回数取得手段
３０８水位取得手段 12, 12a, 12b, 12c, 112x, 112y Read electrode 14 Opposite electrode
100, 101, 102 Capacitor 110, 120, 130 Electrode pair 111, 121, 131 Capacitor 112, 117, 122, 127, 132 Left capacitor 114, 119, 124, 129, 134 Right capacitor 200 Capacitance acquisition unit 300 Calculation Unit 302 Capacitance acquisition means 304 Phase acquisition means 306 Repeat count acquisition means 308 Water level acquisition means

Claims

Each is a capacitor composed of a read electrode extending in the longitudinal direction and a counter electrode facing the read electrode.
A uniform capacitor in which both the distance between the counter electrode and the read electrode and the width along the direction orthogonal to the longitudinal direction of the read electrode are uniform.
The distance between the counter electrode and the read electrode is constant, and the width of the read electrode along the direction orthogonal to the longitudinal direction changes in a periodic function along the longitudinal direction. Equipped with a periodic capacitor,
The periodic function indicated by the first to P periodic capacitors is
The difference between the maximum value and the minimum value and the period L are common to each other.
A capacitance measuring device characterized in that the initial phases are different from each other.

It is equipped with a first to P left capacitor and a first to P right capacitor in which the width of the read electrode changes periodically along the longitudinal direction.
For an integer k of 1 or more and P or less, the sum of the width of the read electrode constituting the k-th left capacitor and the width of the read electrode constituting the k-th right capacitor is constant and equal to each other.
The k-th left capacitor and the k-th right capacitor form a k-period capacitor, and the difference between the capacitance of the k-th left capacitor and the capacitance of the k-th right capacitor is that of the k-period capacitor. Capacitance,
The first left capacitor and the first right capacitor constitute the uniform capacitor, and the sum of the capacitance of the first left capacitor and the capacitance of the first right capacitor is the capacitance of the uniform capacitor. The capacitance measuring device according to claim 1, wherein the capacitor is.

It is equipped with first to P capacitors in which the width of the read electrode changes periodically along the longitudinal direction.
The first to P capacitors each constitute the first to P period capacitors, and the capacitance of the first to P capacitors is the capacitance of the first to P period capacitors, respectively. ,
The first to P capacitors form the uniform capacitor, the sum of the widths of the read electrodes constituting the first to P capacitors is constant, and the sum of the capacitances of the first to P capacitors is constant. The capacitance measuring apparatus according to claim 1, wherein the capacitor is the capacitance of the uniform capacitor.

Condenser part and
Capacitance measuring unit and
Equipped with a calculation unit,
The capacitor section includes the uniform capacitor and the first to P period capacitors.
The capacitance measuring unit acquires the capacitance of the uniform capacitor and the first to P period capacitors, and obtains the capacitance.
The arithmetic unit
A phase acquisition means for acquiring a phase φ from the capacitance of the first to P period capacitors, and a phase acquisition means.
A means for acquiring the number of repetitions N for a period L from the capacitance of the uniform capacitor, and a means for acquiring the number of repetitions.
Any of claims 1 to 3, wherein the height acquisition means for acquiring the height h of the substance between the counter electrode and the read electrode is provided by using the equation h = L × N + L / 2π × φ. The capacitance measuring device according to one item.

The arithmetic unit further
From the sum of the squares of the capacitances of the first to P-periodic capacitors, the specific dielectric constant of the substance between the counter electrode and the read electrode is obtained, and the number of repetitions N is obtained using the specific dielectric constant. The electrostatic capacity measuring apparatus according to claim 4.

The calculation unit includes correction means.
Measured value before correction of the measured value of the capacitance of the first to _P cycle capacitors at height h The average value in any one or a plurality of cycles D ₁ '(h) to DP'(h) However, when the value other than 0 is taken, the correction means corrects the measured value with respect to any one or a plurality of the measured values D ₁ ′ (h) to _DP ′ (h), and the first to the above . The capacitance according to claim 4 or 5, wherein the average value of the corrected measured values D ₁ (h) to DP (h) in one cycle of the _P - cycle capacitor is set to 0. measuring device.

The measured value before correction of the measured value of the capacitance of the _first to _P cycle capacitors at the height h. However, when the value other than 0 is taken, the correction electrode that sets the average value of the corrected measured values D ₁ (h) to DP (h) of the first to _P cycle capacitors to 0 in one cycle. Equipped with
The correction electrode has a value other than 0 as an average value in one cycle . The capacitance measuring device according to any one of claims 1 to 5, wherein the capacitance measuring device is provided so as to be equal to the measured value at the corrected height of 0.

Condenser part and
Capacitance measuring unit and
Equipped with a calculation unit,
The capacitor unit includes the first to P-period capacitors.
The capacitance measuring unit acquires the capacitance of the first to P period capacitors, and obtains the capacitance.
Claims 1 to 3 are characterized in that the arithmetic unit obtains the relative permittivity of a substance between the counter electrode and the read electrode from the sum of the squares of the capacitances of the first to P period capacitors. The capacitance measuring device according to any one of the above items.