JPH0626907A - Level detecting device - Google Patents
Level detecting deviceInfo
- Publication number
- JPH0626907A JPH0626907A JP4081982A JP8198292A JPH0626907A JP H0626907 A JPH0626907 A JP H0626907A JP 4081982 A JP4081982 A JP 4081982A JP 8198292 A JP8198292 A JP 8198292A JP H0626907 A JPH0626907 A JP H0626907A
- Authority
- JP
- Japan
- Prior art keywords
- capacitor
- voltage
- level
- circuit
- level detection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、一対の電極間の静電容
量変化により連続レベルを検出するレベル検出装置に関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a level detecting device for detecting a continuous level by changing a capacitance between a pair of electrodes.
【０００２】[0002]
【従来の技術】液体のレベル変化に伴う一対の電極間の
静電容量変化を検出してレベルを検出するレベル検出装
置として例えば特開昭６２ー１８００４号公報の装置が
ある。この装置は、上記静電容量変化をＣＲ発振回路の
周波数の変化として検出することを開示している。2. Description of the Related Art As a level detecting device for detecting a level by detecting a change in capacitance between a pair of electrodes due to a change in liquid level, there is, for example, a device disclosed in Japanese Patent Laid-Open No. 62-18004. This device discloses that the capacitance change is detected as a change in the frequency of the CR oscillation circuit.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、上記説
明したレベル変化に伴う電極対間の静電容量変化を発振
周波数の変化として検出する場合、ω＝（ＬＣ）ー1/2と
なり、周波数と静電容量Ｃが直線関係をもたないので、
例えばｆ／Ｖ変換した信号電圧が液体のレベル（ほぼ電
極間の静電容量と直線関係を有する）と直線関係をもた
ず、その後の信号処理が複雑となった。However, when detecting the change in capacitance between the electrode pair due to the level change described above as a change in oscillation frequency, ω = (LC) −1/2 , and the frequency and static Since the capacitance C does not have a linear relationship,
For example, the f / V converted signal voltage does not have a linear relationship with the liquid level (which has a linear relationship with the capacitance between the electrodes), and the subsequent signal processing becomes complicated.
【０００４】本発明は、このような問題に鑑みなされた
ものであり、流体のレベル変化と出力信号電圧変化との
間の直線性に優れ、構成が簡単なレベル検出装置を提供
することを、その目的としている。The present invention has been made in view of the above problems, and it is an object of the present invention to provide a level detection device which is excellent in linearity between a fluid level change and an output signal voltage change and which has a simple structure. Its purpose is.
【０００５】[0005]
【課題を解決するための手段】本発明のレベル検出装置
は、被測定流体を収容する容器内の所定位置に所定間隔
を隔てて垂下される一対の長尺状の電極で構成されるレ
ベル検出コンデンサと、前記電極対の一方に定周波数の
交流電圧を印加する発振回路と、前記電極対の他方と所
定の定電位のライン間に接続されるインピーダンス素子
と、前記レベル検出コンデンサと前記インピーダンス素
子との接続点の信号電圧を増幅する増幅回路とを備える
ことを特徴としている。A level detecting device of the present invention is a level detecting device comprising a pair of elongated electrodes suspended at a predetermined position in a container containing a fluid to be measured at a predetermined interval. A capacitor, an oscillating circuit for applying a constant frequency AC voltage to one of the electrode pair, an impedance element connected between the other of the electrode pair and a line of a predetermined constant potential, the level detection capacitor and the impedance element. And an amplifier circuit that amplifies the signal voltage at the connection point with the.
【０００６】好適な態様において、前記インピーダンス
素子のインピーダンスをＺ、前記レベル検出コンデンサ
の静電容量をＣ、前記交流電圧の角周波数をωとする
時、ωＣＺをＯ．１以下とされる。好適な態様におい
て、前記インピーダンス素子は抵抗及びコンデンサの少
なくとも一方からなる。In a preferred mode, when the impedance of the impedance element is Z, the capacitance of the level detecting capacitor is C, and the angular frequency of the AC voltage is ω, ωCZ is 0. It is set to 1 or less. In a preferred aspect, the impedance element includes at least one of a resistor and a capacitor.
【０００７】好適な態様において、前記発振回路は直流
遮断用の直流遮断コンデンサを通じて前記レベル検出コ
ンデンサに前記交流電圧を印加し、前記増幅回路は直流
遮断用の直流遮断コンデンサを通じて入力される前記接
続点の信号電圧を増幅する。好適な態様において、前記
レベル検出コンデンサは同軸筒形状を有し、外筒からな
る外部電極は前記発振回路から交流電圧を給電され、前
記外筒内に同軸状に収容される内部電極が前記増幅回路
に信号電圧を伝送する。In a preferred mode, the oscillating circuit applies the AC voltage to the level detecting capacitor through a DC blocking capacitor for DC blocking, and the amplifying circuit inputs the connecting point through a DC blocking capacitor for DC blocking. Amplifies the signal voltage of. In a preferred aspect, the level detection capacitor has a coaxial cylindrical shape, an outer electrode formed of an outer cylinder is supplied with an AC voltage from the oscillation circuit, and an inner electrode housed coaxially in the outer cylinder is the amplifier. Transmits signal voltage to the circuit.
【０００８】[0008]
【作用】発振回路から出力された交流電圧はレベル検出
コンデンサとインピーダンス素子の直列回路に印加さ
れ、両素子の接続点の分圧が増幅回路により増幅され
る。ここで、インピーダンス素子のインピーダンスを
Ｚ、レベル検出コンデンサの静電容量をＣ、角周波数を
ωとすれば、ωＣＺを１よりなるべく小さくすることに
より、増幅回路から出力される信号電圧の直線性が向上
する。The AC voltage output from the oscillation circuit is applied to the series circuit of the level detection capacitor and the impedance element, and the voltage division at the connection point of both elements is amplified by the amplification circuit. Here, if the impedance of the impedance element is Z, the electrostatic capacity of the level detection capacitor is C, and the angular frequency is ω, by making ωCZ as small as possible, the linearity of the signal voltage output from the amplifier circuit can be reduced. improves.
【０００９】[0009]
【発明の効果】以上説明したように本発明のレベル検出
装置は、発振回路から出力された交流電圧をレベル検出
コンデンサとインピーダンス素子とからなる直列回路に
印加し、両素子の接続点の分圧を検出、増幅する回路構
成を採用しているので、流体のレベル変化に対して直線
性の高い信号電圧を出力することができる。As described above, the level detection device of the present invention applies the AC voltage output from the oscillation circuit to the series circuit composed of the level detection capacitor and the impedance element to divide the voltage at the connection point of both elements. Since a circuit configuration for detecting and amplifying is detected, it is possible to output a signal voltage having high linearity with respect to a fluid level change.
【００１０】[0010]
【実施例】本発明のレベル検出装置の一実施例を図１に
示す。この装置は、発振回路１と、レベル検出用のコン
デンサ回路２と、増幅回路３と、検波回路４と、平滑回
路５とからなる。発振回路１は、一定周波数の正弦波交
流電圧を出力する回路であるが、他の波形の発振回路で
もよい。FIG. 1 shows an embodiment of the level detecting apparatus of the present invention. This device comprises an oscillation circuit 1, a level detecting capacitor circuit 2, an amplifying circuit 3, a detecting circuit 4, and a smoothing circuit 5. The oscillation circuit 1 is a circuit that outputs a sine wave AC voltage having a constant frequency, but may be an oscillation circuit having another waveform.
【００１１】コンデンサ回路２は、順番に直列接続され
た第１の直流遮断コンデンサ２１、レベル検出コンデン
サ６、第２の直流遮断コンデンサ２２と、インピーダン
ス素子７とを有する。インピーダンス素子７の一端はレ
ベル検出コンデンサ６と第２の直流遮断コンデンサ２２
との接続点に接続され、インピーダンス素子７の他端は
接地されている。The capacitor circuit 2 has a first DC blocking capacitor 21, a level detecting capacitor 6, a second DC blocking capacitor 22 and an impedance element 7 which are connected in series in order. One end of the impedance element 7 has a level detection capacitor 6 and a second DC blocking capacitor 22.
And the other end of the impedance element 7 is grounded.
【００１２】増幅回路３は所定の入力インピーダンスを
有するリニア増幅回路であり、ＦＥＴ及びオペアンプに
より構成されている。検波回路４及び平滑回路５の構成
は周知であるので説明を省略する。レベル検出コンデン
サ６を除く他の部品は密閉ケース（図示せず）内に収容
されている。コンデンサ回路２について更に説明する。The amplifier circuit 3 is a linear amplifier circuit having a predetermined input impedance and is composed of an FET and an operational amplifier. Since the configurations of the detection circuit 4 and the smoothing circuit 5 are well known, description thereof will be omitted. Other parts except the level detection capacitor 6 are housed in a sealed case (not shown). The capacitor circuit 2 will be further described.
【００１３】レベル検出コンデンサ６は、図２に示すよ
うに、誘電性の被測定液体（図示せず）を収容する容器
（図示せず）内の所定位置に垂下される同軸円筒からな
る外部電極６２及び内部電極６１を有し、両者の上部に
は樹脂製の蓋６３が嵌められている。この蓋６３は上蓋
部から同軸状に垂下する中央円柱部と外筒部とをもち、
中央円柱部は内部電極６１内に嵌入され、外筒部は外部
電極６２に嵌着されている。内部電極６１及び外部電極
６２の隙間の下部には樹脂製のスペーサ６４が嵌めら
れ、この隙間を一定に保持している。As shown in FIG. 2, the level detecting capacitor 6 is an external electrode made of a coaxial cylinder which is hung at a predetermined position in a container (not shown) which contains a dielectric liquid to be measured (not shown). 62 and an internal electrode 61, and a lid 63 made of resin is fitted on the upper part of both. This lid 63 has a central cylindrical portion and an outer tubular portion that hang down coaxially from the upper lid portion,
The central cylindrical portion is fitted in the inner electrode 61, and the outer cylindrical portion is fitted in the outer electrode 62. A resin spacer 64 is fitted under the gap between the internal electrode 61 and the external electrode 62 to keep the gap constant.
【００１４】内部電極６１及び外部電極６２の上端には
爪６１ａ及び６２ａが上方に伸びており、これら爪６１
ａ及び６２ａは一対の信号ケーブルの両終端に個別には
んだ付けされている。信号ケーブル６４はそれぞれ金網
シールド線からなり、上記密閉ケースまで延設されてい
る。外部電極６２の下端には底付き円筒形状の樹脂又は
金属製のキャップ６５が嵌着固定されており、キャップ
６５の側壁には燃料流出入用の小孔６６が開口されてい
る。この小孔６６はメカニカルローパスフィルタとして
作用する。Claws 61a and 62a extend upward at the upper ends of the inner electrode 61 and the outer electrode 62, respectively.
a and 62a are individually soldered to both ends of the pair of signal cables. Each of the signal cables 64 is composed of a wire mesh shield wire and extends to the above-mentioned sealed case. A cylindrical resin or metal cap 65 with a bottom is fitted and fixed to the lower end of the external electrode 62, and a small hole 66 for fuel inflow and outflow is formed in the side wall of the cap 65. This small hole 66 acts as a mechanical low pass filter.
【００１５】以下、この装置の作動を説明する。発振回
路１の交流電圧は直流遮断コンデンサ２１、レベル検出
コンデンサ６、インピーダンス素子７にそれぞれ分圧さ
れる。なお、コンデンサ２２のインピーダンスはインピ
ーダンス素子７のインピーダンスに比べて小さくまた、
増幅回路の入力端と接地間のインピーダンスは大きく、
コンデンサ２２側に分流する電流成分は無視して考え
る。The operation of this device will be described below. The AC voltage of the oscillator circuit 1 is divided into a DC blocking capacitor 21, a level detecting capacitor 6, and an impedance element 7, respectively. The impedance of the capacitor 22 is smaller than that of the impedance element 7, and
The impedance between the input end of the amplifier circuit and ground is large,
The current component shunting to the capacitor 22 side is ignored and considered.
【００１６】誘電性の液体のレベル変化が生じると、電
極６１、６２からなるレベル検出コンデンサ６の容量変
化ΔＣはこのレベル変化量ΔＬにほぼ比例する。コンデ
ンサ６とインピーダンス素子７との接続点の信号電圧
（分圧）Ｖｃは、直流遮断コンデンサ２１のインピーダ
ンスをＺ１、レベル検出コンデンサ６のインピーダンス
をＺ２＝１／ｊωＣ、インピーダンス素子７のインピー
ダンスをＺ３とし、発振回路１が出力する交流電圧をＶ
ｏ、その出力インピーダンスは小さくて無視できるもの
とすると、 Ｖｃ＝（Ｚ３／（Ｚ１＋（１／ｊωＣ）＋Ｚ３））Ｖｏ
となる。When the level change of the dielectric liquid occurs, the capacity change ΔC of the level detecting capacitor 6 including the electrodes 61 and 62 is substantially proportional to the level change amount ΔL. The signal voltage (divided voltage) Vc at the connection point between the capacitor 6 and the impedance element 7 is Z1 as the impedance of the DC blocking capacitor 21, Z2 = 1 / jωC as the impedance of the level detection capacitor 6, and Z3 as the impedance of the impedance element 7. , The AC voltage output from the oscillation circuit 1 is V
o, assuming that its output impedance is small and can be ignored, Vc = (Z3 / (Z1 + (1 / jωC) + Z3)) Vo
Becomes
【００１７】 ＝ ｊωＣＺ３Ｖｏ／（１＋ｊωＣ（Ｚ１＋Ｚ３）） いま、ｊωＣ（Ｚ１＋Ｚ３）を１より大幅に小さくなる
ように例えばＯ．１以下とすれば、Ｖｃ＝ｊωＣＺ３Ｖ
ｏとみなすことができ、信号電圧Ｖｃはレベル検出コン
デンサ６の静電容量Ｃに比例し、Ｃの変化ΔＣがレベル
変化ΔＬに比例するので、信号電圧Ｖｃの変化はレベル
変化ΔＬに比例すると見なすことができる。= JωCZ3Vo / (1 + jωC (Z1 + Z3)) Now, jωC (Z1 + Z3) is set to be significantly smaller than 1, for example, O.I. If 1 or less, Vc = jωCZ3V
Since the signal voltage Vc is proportional to the electrostatic capacitance C of the level detection capacitor 6 and the change ΔC of C is proportional to the level change ΔL, it is considered that the change of the signal voltage Vc is proportional to the level change ΔL. be able to.
【００１８】すなわち、ω、Ｃ、Ｚ１、Ｚ３を小さくす
ればよく、Ｚ１の静電容量できるだけ大きく、Ｚ３がコ
ンデンサであればその静電容量をできるだけ大きく、抵
抗であればできるだけ抵抗値を小さくすることが好まし
いが、あまり小さいと信号電圧Ｖｃも小さくなり、ＳＮ
比が低下するのでそれとの兼ね合いで決定すべきであ
る。That is, ω, C, Z1, and Z3 may be reduced, and the electrostatic capacitance of Z1 is as large as possible. If Z3 is a capacitor, its electrostatic capacitance is as large as possible, and if it is a resistor, the resistance value is as small as possible. However, if it is too small, the signal voltage Vc also becomes small, and SN
The ratio decreases, and it should be decided in consideration of it.
【００１９】接続点の信号電圧Ｖｃは直流遮断コンデン
サ２２を通じて増幅回路３で増幅され、検波回路４で検
波され、平滑回路５で直流化されて出力される。なお、
上記した直流遮断コンデンサ２１、２２はレベル検出コ
ンデンサ６に直流電流が印加されるのを防止するもので
あり、直流電流の漏電などの事故を防ぐことができる。The signal voltage Vc at the connection point is amplified by the amplifier circuit 3 through the DC blocking capacitor 22, detected by the detection circuit 4, converted into DC by the smoothing circuit 5, and output. In addition,
The DC blocking capacitors 21 and 22 described above prevent a DC current from being applied to the level detection capacitor 6, and can prevent accidents such as DC current leakage.
【００２０】本実施例では、同軸円筒状のレベル検出コ
ンデンサ６の外部電極６２が発振回路１側に接続され、
内部電極６１が信号電極Ｖｃの検出点として増幅回路３
に接続されている。このようにすれば、外部電極６２と
タンク（図示せず）などとの間の寄生容量がレベル検出
コンデンサ６の取り付け位置などの変動により変化して
も、信号電圧Ｖｃの変化となりにくい利点がある。In this embodiment, the external electrode 62 of the coaxial cylindrical level detecting capacitor 6 is connected to the oscillator circuit 1 side,
The internal electrode 61 serves as a detection point of the signal electrode Vc and serves as the amplifier circuit 3.
It is connected to the. By doing so, even if the parasitic capacitance between the external electrode 62 and the tank (not shown) or the like changes due to a change in the mounting position of the level detection capacitor 6 or the like, the signal voltage Vc is unlikely to change. .
【００２１】以下、本実施例の他の変形態様を説明す
る。直流遮断コンデンサ２１、２２は省略可能である。
例えば、直流遮断コンデンサ２１を省略すれば、上記式
からわかるように直線性が向上する。インピーダンス素
子７は、コンデンサや抵抗の他、リアクタンスでも置換
することができる。ただ、インピーダンス素子７を抵抗
とすれば、レベル検出コンデンサ６の内部電極６１は直
流的に接地されることとなり、レベル検出コンデンサ６
と抵抗７との接続点やケーブルに静電気などが帯電する
ことが無く、高周波ノイズの重畳防止や安全性において
有利である。また、直流遮断コンデンサ２２を省略する
場合、増幅回路３の入力インピーダンスを小さくすれ
ば、この入力インピーダンスをインピーダンス素子とし
て採用することができる。Another modification of this embodiment will be described below. The DC blocking capacitors 21 and 22 can be omitted.
For example, if the DC blocking capacitor 21 is omitted, the linearity is improved as can be seen from the above formula. The impedance element 7 can be replaced with a reactance in addition to a capacitor and a resistor. However, if the impedance element 7 is a resistor, the internal electrode 61 of the level detecting capacitor 6 is grounded in a direct current manner, and the level detecting capacitor 6 is
Since static electricity or the like is not charged on the connection point between the resistor 7 and the resistor 7 or the cable, it is advantageous in terms of prevention of superposition of high frequency noise and safety. Further, when the DC blocking capacitor 22 is omitted, if the input impedance of the amplifier circuit 3 is reduced, this input impedance can be adopted as an impedance element.
【００２２】更に、レベル検出コンデンサ６の内部電極
６１は円筒の他に円柱とすることもできる。又、被測定
流体としては粉体であってもよい。Furthermore, the internal electrode 61 of the level detecting capacitor 6 may be a cylinder instead of a cylinder. The fluid to be measured may be powder.
【図１】本発明の一実施例を示す等価回路図FIG. 1 is an equivalent circuit diagram showing an embodiment of the present invention.
【図２】レベル検出コンデンサの断面図、FIG. 2 is a sectional view of a level detection capacitor,
１…発振回路、 ２…コンデンサ回路、 ３…増幅回路、 ４…検波回路、 ５…平滑回路、 ６…レベル検出コンデンサ、 ７…インピーダンス素子。 ２１、２２…直流遮断コンデンサ、 DESCRIPTION OF SYMBOLS 1 ... Oscillation circuit, 2 ... Capacitor circuit, 3 ... Amplification circuit, 4 ... Detection circuit, 5 ... Smoothing circuit, 6 ... Level detection capacitor, 7 ... Impedance element. 21, 22 ... DC blocking capacitors,
Claims (5)
所定間隔を隔てて垂下される一対の長尺状の電極で構成
されるレベル検出コンデンサと、 前記電極対の一方に定周波数の交流電圧を印加する発振
回路と、 前記電極対の他方と所定の定電位のライン間に接続され
るインピーダンス素子と、 前記レベル検出コンデンサと前記インピーダンス素子と
の接続点の信号電圧を増幅する増幅回路とを備えること
を特徴とするレベル検出装置。1. A level detection capacitor composed of a pair of elongated electrodes suspended at a predetermined position in a container containing a fluid to be measured at a predetermined interval, and one of the electrode pairs having a constant frequency. An oscillation circuit for applying an AC voltage, an impedance element connected between the other of the pair of electrodes and a line of a predetermined constant potential, and an amplification circuit for amplifying a signal voltage at a connection point between the level detection capacitor and the impedance element. A level detection device comprising:
をＺ、前記レベル検出コンデンサの静電容量をＣ、前記
交流電圧の角周波数をωとする時、ωＣＺをＯ．１以下
とした請求項１記載のレベル検出装置。2. When the impedance of the impedance element is Z, the capacitance of the level detection capacitor is C, and the angular frequency of the AC voltage is ω, ωCZ is 0. The level detection device according to claim 1, wherein the level detection device is 1 or less.
抵抗の少なくとも一方からなる請求項１記載のレベル検
出装置。3. The level detecting device according to claim 1, wherein the impedance element comprises at least one of a capacitor and a resistor.
デンサを通じて前記レベル検出コンデンサに前記交流電
圧を印加し、前記増幅回路は直流遮断用の直流遮断コン
デンサを通じて入力される前記接続点の信号電圧を増幅
するものである請求項１記載のレベル検出装置。4. The oscillation circuit applies the AC voltage to the level detection capacitor through a DC blocking capacitor for DC blocking, and the amplifier circuit inputs a signal voltage at the connection point through a DC blocking capacitor for DC blocking. The level detection device according to claim 1, which amplifies the level.
有し、外筒からなる外部電極は前記発振回路から交流電
圧を給電され、前記外筒内に同軸状に収容される内部電
極が前記増幅回路に信号電圧を伝送するものである請求
項１記載のレベル検出装置。5. The level detecting capacitor has a coaxial cylindrical shape, an outer electrode formed of an outer cylinder is supplied with an AC voltage from the oscillation circuit, and an inner electrode coaxially housed in the outer cylinder is the amplifier. 2. The level detecting device according to claim 1, which transmits a signal voltage to a circuit.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4081982A JPH07113565B2 (en) | 1992-04-03 | 1992-04-03 | Level detector |
| US08/328,571 US5611240A (en) | 1992-04-03 | 1994-10-24 | Level detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4081982A JPH07113565B2 (en) | 1992-04-03 | 1992-04-03 | Level detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0626907A true JPH0626907A (en) | 1994-02-04 |
| JPH07113565B2 JPH07113565B2 (en) | 1995-12-06 |
Family
ID=13761693
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4081982A Expired - Lifetime JPH07113565B2 (en) | 1992-04-03 | 1992-04-03 | Level detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07113565B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007240262A (en) * | 2006-03-07 | 2007-09-20 | Yazaki Corp | Liquid level sensor |
| JP2010169482A (en) * | 2009-01-21 | 2010-08-05 | Shin Etsu Handotai Co Ltd | Sediment detection method and sediment detector |
| EP3449226B1 (en) * | 2016-04-29 | 2020-12-16 | Endress+Hauser SE+Co. KG | Coupling element for a capacitive fill-level measuring apparatus |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4877189A (en) * | 1972-01-25 | 1973-10-17 | ||
| JPS61188818A (en) * | 1985-02-15 | 1986-08-22 | 日東電工株式会社 | Anisotropic conducting sheet |
-
1992
- 1992-04-03 JP JP4081982A patent/JPH07113565B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4877189A (en) * | 1972-01-25 | 1973-10-17 | ||
| JPS61188818A (en) * | 1985-02-15 | 1986-08-22 | 日東電工株式会社 | Anisotropic conducting sheet |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007240262A (en) * | 2006-03-07 | 2007-09-20 | Yazaki Corp | Liquid level sensor |
| JP2010169482A (en) * | 2009-01-21 | 2010-08-05 | Shin Etsu Handotai Co Ltd | Sediment detection method and sediment detector |
| EP3449226B1 (en) * | 2016-04-29 | 2020-12-16 | Endress+Hauser SE+Co. KG | Coupling element for a capacitive fill-level measuring apparatus |
| US10895488B2 (en) | 2016-04-29 | 2021-01-19 | Endress+Hauser SE+Co. KG | Coupling element for a capacitive fill level measuring device |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07113565B2 (en) | 1995-12-06 |
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