JPH0334807B2 - - Google Patents
Info
- Publication number
- JPH0334807B2 JPH0334807B2 JP20423484A JP20423484A JPH0334807B2 JP H0334807 B2 JPH0334807 B2 JP H0334807B2 JP 20423484 A JP20423484 A JP 20423484A JP 20423484 A JP20423484 A JP 20423484A JP H0334807 B2 JPH0334807 B2 JP H0334807B2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- eddy current
- current sensor
- amplifier
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000001514 detection method Methods 0.000 claims description 20
- 230000001360 synchronised effect Effects 0.000 claims description 16
- 239000000284 extract Substances 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 description 14
- 238000010586 diagram Methods 0.000 description 8
- 230000003321 amplification Effects 0.000 description 7
- 238000003199 nucleic acid amplification method Methods 0.000 description 7
- 239000002184 metal Substances 0.000 description 4
- 230000010355 oscillation Effects 0.000 description 4
- 239000007788 liquid Substances 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
Description
【発明の詳細な説明】
〔発明の技術分野〕
本発明は、直流帰還型渦流距離計の改良に関す
る。DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a DC feedback type eddy current distance meter.
非接触条件下において被測定体との距離を計測
する技術としては、従来、レーザ光、超音波、ま
たは渦電流を用いた距離計等がある。第３図は渦
電流を利用した従来の渦流式距離計の構成図であ
る。同図において１は渦流センサであつて、この
渦流センサ１は１次コイル１−１と１対の２次コ
イル１−２，１−３から構成され、１次コイル１
−１には発振器２から出力される所定周波数の交
流信号が増幅器３を介して供給されるようになつ
ている。この渦流センサ１は金属圧延板や溶融金
属液体等の被測定体４上に近接配置されている。
この状態において前記交流信号が渦流センサに供
給されると、１次コイル１−１から交流磁界が発
生されて被測定体４と交差し、これにより被測定
体４の表面に渦電流が発生する。この渦電流によ
つて、被測定体４からは１次コイル１−１より発
生された交流磁界に対して反作用となる磁界が発
生する。これにより、２次コイル１−２，１−３
と交差する磁界が変化し、各２次コイル１−２，
１−３はそれぞれ値の異なつた電圧が誘起され
る。ここで、渦電流による磁界変化の影響は、被
測定体４により近接した２次コイル１−２側に対
して大きくなつているので、１対の２次コイル１
−２，１−３から差分の電圧が発生し、この差分
電圧は信号増幅器５により所定値まで増幅されて
増幅器３の正入力端子に帰還される。このときの
増幅器３の出力電圧eputは、渦流センサ１と被測
定体４との相対距離ｌに対応した値となる。ここ
で、出力電圧eputは、次式により表わされる。
Conventional techniques for measuring the distance to a measured object under non-contact conditions include distance meters that use laser light, ultrasonic waves, or eddy currents. FIG. 3 is a configuration diagram of a conventional eddy current distance meter that utilizes eddy currents. In the figure, 1 is an eddy current sensor, and this eddy current sensor 1 is composed of a primary coil 1-1 and a pair of secondary coils 1-2, 1-3.
-1 is supplied with an AC signal of a predetermined frequency output from an oscillator 2 via an amplifier 3. This eddy current sensor 1 is placed close to an object to be measured 4 such as a rolled metal plate or molten metal liquid.
When the AC signal is supplied to the eddy current sensor in this state, an AC magnetic field is generated from the primary coil 1-1 and intersects the object to be measured 4, thereby generating an eddy current on the surface of the object to be measured 4. . Due to this eddy current, a magnetic field is generated from the object to be measured 4 that is a reaction to the alternating current magnetic field generated by the primary coil 1-1. As a result, the secondary coils 1-2, 1-3
The magnetic field intersecting with changes, and each secondary coil 1-2,
1-3, voltages having different values are induced respectively. Here, since the influence of magnetic field changes due to eddy currents is greater on the side of the secondary coil 1-2 that is closer to the object to be measured 4, the pair of secondary coils 1-2
A differential voltage is generated from -2 and 1-3, and this differential voltage is amplified to a predetermined value by the signal amplifier 5 and fed back to the positive input terminal of the amplifier 3. The output voltage e put of the amplifier 3 at this time has a value corresponding to the relative distance l between the eddy current sensor 1 and the object to be measured 4 . Here, the output voltage e put is expressed by the following equation.
eput＝−G1・eio／１−G1・G2・Ｋ＝−G1・e
io／１−G1・G2（eput／Zp）（M1−M2）……(1)
なお、G1は増幅器３のオープン増幅度、eioは発
振器２の出力電圧、G2は信号増幅器５の増幅度、
Zpは１次コイル１−１のインピーダンス、M1お
よびM2は１次コイル１−１と１対の２次コイル
１−２，１−３との間の各相互インピーダンスで
ある。 e put = −G 1・e io /1−G 1・G 2・K=−G 1・e
io /1−G 1・G 2 (e put /Z p ) (M 1 −M 2 )……(1) In addition, G 1 is the open amplification degree of amplifier 3, e io is the output voltage of oscillator 2, and G 2 is the amplification degree of the signal amplifier 5,
Z p is the impedance of the primary coil 1-1, and M 1 and M 2 are mutual impedances between the primary coil 1-1 and the pair of secondary coils 1-2 and 1-3.
したがつて、増幅器３の出力電圧eputを計測す
れば間接的に相対距離ｌが求められる。 Therefore, by measuring the output voltage e put of the amplifier 3, the relative distance l can be indirectly determined.
ところで、第(1)式の分母において各相互インピ
ーダンスM1，M2の差と（eput／Zp）とが掛け算
されているが、この場合各相互インピーダンス
M1，M2の各虚数部分が等しくないと、出力電圧
eputは虚数部分をもつた式で表わされることにな
る。このように虚数部分をもつことは実際の出力
電圧eputでは位相偏位が発生することになる。と
ころで、この位相偏位の要因としては次のような
ことが考えられる。すなわち、
１対の２次コイル１−２，１−３の各インピ
ーダンスのアンバランス。
By the way, in the denominator of equation (1), the difference between each mutual impedance M 1 and M 2 is multiplied by (e put /Z p ), but in this case, each mutual impedance
If the imaginary parts of M 1 and M 2 are not equal, the output voltage
e put will be expressed as an expression with an imaginary part. Having an imaginary part in this way means that a phase deviation occurs in the actual output voltage e put . By the way, the following factors can be considered as factors for this phase deviation. In other words, the impedance imbalance of the pair of secondary coils 1-2 and 1-3.
被測定体４の電気的特性と磁気的特性。 Electrical characteristics and magnetic characteristics of the object to be measured 4.
１次コイル１−１に供給する交流信号（交流
電流）の周波数。 Frequency of the alternating current signal (alternating current) supplied to the primary coil 1-1.
渦流センサ１全体の径および形状。 Diameter and shape of the entire eddy current sensor 1.
信号増幅器５の入力インピーダンス値とその
変動。 Input impedance value of signal amplifier 5 and its variation.
過流センサ１と装置本体つまり増幅器３、信
号増幅器５とを結線する同軸ケーブルの分布容
量のアンバランスおよび温度変動による分布容
量の変動。 Unbalance in the distributed capacitance of the coaxial cable that connects the excess current sensor 1 and the main body of the device, that is, the amplifier 3 and the signal amplifier 5, and fluctuations in the distributed capacitance due to temperature fluctuations.
装置本体（IC）の位相偏位、プリント基板
の分布容量
などである。 These include the phase deviation of the device body (IC) and the distributed capacitance of the printed circuit board.
ところで、位相偏位が大きくなると増幅器３は
正常に動作することができなくなり、この結果出
力電圧eputは、第４図に示すように正常動作時の
出力特性(イ)と比較して出力特性(ロ)のように非常に
大きな誤差を含んだものとなつてしまう。さら
に、甚だしくは帰還ループにおいて自己発振する
こともある。 By the way, if the phase deviation becomes large, the amplifier 3 will not be able to operate normally, and as a result, the output voltage e put will have a different output characteristic compared to the output characteristic (A) during normal operation, as shown in Figure 4. This results in a result that contains a very large error as shown in (b). Furthermore, self-oscillation may occur in the feedback loop.
本発明は上記実情に基づいてなされたもので、
その目的とするところは、位相偏位による発振現
象をなくし得て、安定に動作し、高精度な直流帰
還型渦流距離計を提供することにある。
The present invention was made based on the above circumstances, and
The purpose is to provide a DC feedback type eddy current distance meter that can eliminate oscillation phenomena due to phase deviation, operates stably, and has high accuracy.
本発明は、被測定体上に所定周波数の交流信号
が供給される１次コイルと各誘起電圧の差電圧を
出力する１対の２次コイルとから構成される渦流
センサを配置し、前記２次コイルから出力される
差電圧を同期検波回路により前記交流信号に同期
して検波して直流信号として出力し、この直流信
号を予め設定されたレベルの直流信号が加わる差
動増幅回路に与え、この差動増幅回路の出力信号
に応じて１次コイルに供給する交流信号のレベル
を制御してこの差動増幅回路から渦流センサと被
測定体との距離に対応した信号を出力するように
した直流帰還型渦流距離計である。
The present invention provides an eddy current sensor that includes a primary coil to which an alternating current signal of a predetermined frequency is supplied and a pair of secondary coils that output a voltage difference between respective induced voltages on an object to be measured. The differential voltage output from the next coil is detected by a synchronous detection circuit in synchronization with the alternating current signal and output as a direct current signal, and this direct current signal is applied to a differential amplifier circuit to which a direct current signal of a preset level is added, The level of the alternating current signal supplied to the primary coil is controlled according to the output signal of this differential amplifier circuit, so that the differential amplifier circuit outputs a signal corresponding to the distance between the eddy current sensor and the object to be measured. It is a DC feedback type eddy current distance meter.
以下、本発明の一実施例について図面を参照し
て説明する。第１図は本発明の直流帰還型渦流距
離計の構成図である。なお、第３図と同一部分に
は同一符号を付してある。すなわち、１は渦流セ
ンサであつて、１−１は１次コイル、１−２，１
−３は対をなす２次コイルであり、２は発振器、
４は溶融金属液体、圧延板等の被測定体である。
渦流センサ１の１次コイル１−１には発振器２か
ら直流一交流変換回路１０（以下、DC／AC変換
回路と指称する）および増幅度１に設定された電
力増幅器１１を介して交流信号が供給されるよう
になつており、また２次コイル１−２，１−３は
差動型信号増幅器１２の入力端に接続されてい
る。なお、DC／AC変換回路１０は、直流増幅器
１３から出力される信号Eputを受け、発振器２か
らの交流信号の電圧レベルを信号Eputに比例制御
して電力増幅器１１に送出する機能を持つたもの
である。
An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a DC feedback type eddy current distance meter according to the present invention. Note that the same parts as in FIG. 3 are given the same reference numerals. That is, 1 is an eddy current sensor, 1-1 is a primary coil, 1-2, 1
-3 is a pair of secondary coils, 2 is an oscillator,
Reference numeral 4 indicates an object to be measured such as a molten metal liquid or a rolled plate.
An AC signal is supplied to the primary coil 1-1 of the eddy current sensor 1 from an oscillator 2 via a DC/AC conversion circuit 10 (hereinafter referred to as a DC/AC conversion circuit) and a power amplifier 11 set to an amplification level of 1. The secondary coils 1-2 and 1-3 are connected to the input terminal of the differential signal amplifier 12. Note that the DC/AC conversion circuit 10 has a function of receiving the signal E put output from the DC amplifier 13 , controlling the voltage level of the AC signal from the oscillator 2 proportionally to the signal E put , and sending it to the power amplifier 11 . It is something that
さらに差動型信号増幅器１２の出力端は同期検
波回路１４に接続されている。この同期検波回路
１４は、発振器２から出力される所定周波数の交
流信号に同期して差動型信号増幅器１２の出力信
号を検波し、この検波によつて得られた直流信号
ESを直流増幅器１３の正入力端子に供給するもの
である。この直流増幅器１３は、自身の負入力端
子に直流基準電圧発生回路１５から予め設定され
たレベルの直流基準電圧ERが加わつており、よ
つて、この直流基準電圧ERと同期検波回路１４
から得られた直流信号ESの差電圧Eputを出力する
ものであつて、この差電圧Eputが渦流センサ１と
被測定体４との距離に対応した値となる。 Further, the output end of the differential signal amplifier 12 is connected to a synchronous detection circuit 14. This synchronous detection circuit 14 detects the output signal of the differential signal amplifier 12 in synchronization with the AC signal of a predetermined frequency output from the oscillator 2, and generates a DC signal obtained by this detection.
ES is supplied to the positive input terminal of the DC amplifier 13. This DC amplifier 13 has a DC reference voltage E R of a preset level applied from the DC reference voltage generation circuit 15 to its own negative input terminal, and therefore, this DC reference voltage E R and the synchronous detection circuit 14
The difference voltage E put of the DC signal E S obtained from the eddy current sensor 1 is output, and this difference voltage E put has a value corresponding to the distance between the eddy current sensor 1 and the object to be measured 4 .
次に上記の如く構成された距離計の動作につい
て説明する。渦流センサ１が被測定体４上の近接
した位置に置かれ、この渦流センサ１の１次コイ
ル１−１に発振器２から所定周波数の交流信号が
DC／AC変換回路１０および電力増幅器１１を介
して供給されると、１次コイル１−１からは交流
磁界が発生し、この交流磁界は被測定体４と交差
する。すると、被測定体４の表面に渦電流が発生
し、この渦電流によつて１次コイル１−１から発
生された交流磁界に対して反作用となる磁界が発
生する。この磁界の反作用により２次コイル１−
２，１−３と交差する交流磁界が変化し、その変
化は被測定金属体４に近い側のコイル１−２に対
して大きくなる。したがつて、各２次コイル１−
２，１−３の各誘起電圧はそれぞれ異なつた電圧
値となる。そこで、２次コイル１−２の誘起電圧
をeS1、２次コイル１−３の誘起電圧をeS2とする
と、差動型信号増幅器１２からは（eS1−eS2）Gb
＝eSなる信号が出力される。なお、Gbは差動型信
号増幅器１２の増幅度である。 Next, the operation of the distance meter configured as described above will be explained. An eddy current sensor 1 is placed close to the object to be measured 4, and an alternating current signal of a predetermined frequency is sent from an oscillator 2 to the primary coil 1-1 of the eddy current sensor 1.
When supplied via the DC/AC conversion circuit 10 and the power amplifier 11, an alternating current magnetic field is generated from the primary coil 1-1, and this alternating magnetic field intersects the object to be measured 4. Then, an eddy current is generated on the surface of the object to be measured 4, and this eddy current generates a magnetic field that acts as a reaction to the alternating current magnetic field generated from the primary coil 1-1. Due to the reaction of this magnetic field, the secondary coil 1-
2 and 1-3 changes, and the change becomes larger for the coil 1-2 closer to the metal object 4 to be measured. Therefore, each secondary coil 1-
The induced voltages 2 and 1-3 have different voltage values. Therefore, if the induced voltage of the secondary coil 1-2 is e S1 and the induced voltage of the secondary coil 1-3 is e S2 , the differential signal amplifier 12 outputs (e S1 - e S2 ) G b
= e S signal is output. Note that G b is the amplification degree of the differential signal amplifier 12.
この信号eSは同期検波回路１４に加えられ、こ
の同期検波回路１４により検波される。つまり、
同期検波回路１４は、発振器２から出力される交
流信号に同期して信号eSを検波し、この検波によ
り得られた直流信号ES＝eScosθを出力する。した
がつて、差動型信号増幅器１２の出力信号eSに位
相偏位があつても、この位相偏位成分は除かれ
る。 This signal e S is applied to the synchronous detection circuit 14 and detected by the synchronous detection circuit 14 . In other words,
The synchronous detection circuit 14 detects the signal e S in synchronization with the AC signal output from the oscillator 2, and outputs the DC signal E S =e S cos θ obtained by this detection. Therefore, even if there is a phase deviation in the output signal e S of the differential signal amplifier 12, this phase deviation component is removed.
そして、同期検波回路１４の出力信号ESは直流
増幅器１３に送られすなわち正帰還され、これに
より直流増幅器１３からは、直流基準電圧ERと
出力信号ERとの差電圧が増幅されてDC／AC変換
回路１０に加えられる。そして、DC／AC変換回
路１０は、入力された信号の電圧値に比例して発
振器２からの交流信号の電圧値を制御し、その交
流信号を電力増幅器１１を介して１次コイル１−
１に供給する。このときの直流増幅器１３の出力
電圧Eputは渦流センサ１と被測定体４との距離l0
に対応した値となる。ここで、出力電圧Eputは次
式により表わされる。すなわち、
Eput＝−ER・Ga・Ｋ／１−Ga・Gb・
Ｋ（ep／Zp）（M1−M2）Ｎ……(2)
である。ここで、ＫはDC／AC変換回路１０の変
換効率、Gaは直流増幅器１３のオープン増幅度、
Gbは差動型信号増幅器１２の増幅度、Ｎは同期
検波回路１４の変換効率、epは電力増幅器１１の
出力電圧である。したがつて、第(2)式からER，
Ga，Gb，ＫおよびＮの各値が固定設定されれば、
直流増幅器１３の出力電圧Eputは渦流センサ１と
被測定体４との相対距離に対応した値となること
が判る。 Then, the output signal E S of the synchronous detection circuit 14 is sent to the DC amplifier 13, that is, it is positively fed back, and as a result, the difference voltage between the DC reference voltage E R and the output signal E R is amplified and the DC /AC conversion circuit 10. Then, the DC/AC conversion circuit 10 controls the voltage value of the AC signal from the oscillator 2 in proportion to the voltage value of the input signal, and passes the AC signal through the power amplifier 11 to the primary coil 1 -
Supply to 1. The output voltage E put of the DC amplifier 13 at this time is the distance l 0 between the eddy current sensor 1 and the object to be measured 4
The value corresponds to Here, the output voltage E put is expressed by the following equation. That is, E put = −E R・G a・K/1−G a・G b・
K( ep / Zp )( M1 - M2 )N...(2). Here, K is the conversion efficiency of the DC/AC conversion circuit 10, G a is the open amplification degree of the DC amplifier 13,
G b is the amplification degree of the differential signal amplifier 12 , N is the conversion efficiency of the synchronous detection circuit 14 , and e p is the output voltage of the power amplifier 11 . Therefore, from equation (2), E R ,
If the values of G a , G b , K and N are fixed,
It can be seen that the output voltage Eput of the DC amplifier 13 has a value corresponding to the relative distance between the eddy current sensor 1 and the object to be measured 4.
第２図は、第１図に示す距離計により得られた
出力特性図である。なお、渦流センサ１としては
30mmφ径のものが用いられている。 FIG. 2 is an output characteristic diagram obtained by the rangefinder shown in FIG. 1. In addition, as the eddy current sensor 1,
A diameter of 30mmφ is used.
このように本発明の距離計においては、渦流セ
ンサ１の各２次コイル１−２，１−３の各誘起電
圧の差電圧を同期検波回路１４により１次コイル
１−１に供給する交流信号と同期して検波し、こ
の検波により得られた直流信号ESを直流増幅器１
３に帰還し、さらに直流増幅器１３の出力電圧を
DC／AC変換回路１０に送つて１次コイル１−１
に供給する交流信号の電圧レベルを制御し、これ
により直流増幅器１３の出力電圧Eputを距離l0に
対応するものとしたので、位相偏位により出力電
圧Eputが誤差の含んだ値となつたり、また帰還ル
ープにおいて発振が起こつたりすることはなく距
離計全体としての動作が安定する。したがつて被
測定体４が高温の例えば溶解液であつて渦流セン
サ１の配置される位置が悪環境であると、渦流セ
ンサ１の２次コイル１−２，１−３の各インピー
ダンスがアンバランスになるなどして位相偏位が
起こるが、本発明の距離計を適用すれば同期検波
回路１４により直流化して帰還させるので悪還境
下にあつても発振は起こらず安定した動作で距離
が測定できる。 In this way, in the distance meter of the present invention, the difference voltage between the induced voltages of the secondary coils 1-2 and 1-3 of the eddy current sensor 1 is used as an AC signal to be supplied to the primary coil 1-1 by the synchronous detection circuit 14. The DC signal E S obtained by this detection is sent to the DC amplifier 1.
3, and further output voltage of DC amplifier 13.
Primary coil 1-1 sent to DC/AC conversion circuit 10
Since the voltage level of the AC signal supplied to the DC amplifier 13 is controlled to make the output voltage E put of the DC amplifier 13 correspond to the distance l 0 , the output voltage E put becomes a value containing an error due to the phase deviation. Also, oscillation does not occur in the feedback loop, and the operation of the rangefinder as a whole is stable. Therefore, if the object to be measured 4 is a high-temperature solution, for example, and the eddy current sensor 1 is placed in a bad environment, the impedance of each of the secondary coils 1-2, 1-3 of the eddy current sensor 1 will be Phase deviation occurs due to imbalance, but if the distance meter of the present invention is applied, the synchronous detection circuit 14 converts it to direct current and feeds it back, so even under adverse conditions, oscillation does not occur and the distance can be measured with stable operation. can be measured.
また、従来の距離計では、オシロスコープ等に
より各回路における出力電圧の位相等を調整、点
検していたが、本発明の距離計では帰還ループを
直流化したので従来のような複雑な調整、点検が
なくなりメンテナンスが簡単となる。 In addition, in conventional rangefinders, the phase of the output voltage in each circuit was adjusted and inspected using an oscilloscope, etc., but in the rangefinder of the present invention, the feedback loop is made direct current, so complicated adjustments and inspections are not required. This eliminates the need for maintenance.
さらに、従来の帰還増幅型渦流距離計と同等以
上の測定スパンが得られる。 Furthermore, a measurement span equal to or greater than that of conventional feedback amplification type eddy current distance meters can be obtained.
本発明によれば、渦流センサの１対の２次コイ
ル間の差電圧を同期検波回路により渦流センサの
１次コイルに供給する交流信号に同期して検波
し、この検波により得られた直流信号を直流増幅
器に加え、さらにこの直流増幅器の出力信号に比
例して交流信号を制御し、このとき得られる直流
増幅器の出力信号から渦流センサと被測定体との
距離を求めるようにしたので、帰還ループにおけ
る位相偏位による発振現象をなくし得て安定に動
作しかつメンテナンスフリに有効な高精度な直流
帰還型渦流距離計を提供できる。
According to the present invention, a differential voltage between a pair of secondary coils of an eddy current sensor is detected by a synchronous detection circuit in synchronization with an AC signal supplied to the primary coil of the eddy current sensor, and a DC signal obtained by this detection is obtained. is added to the DC amplifier, the AC signal is controlled in proportion to the output signal of this DC amplifier, and the distance between the eddy current sensor and the object to be measured is determined from the output signal of the DC amplifier obtained at this time. It is possible to provide a highly accurate DC feedback type eddy current distance meter that can eliminate oscillation phenomena due to phase deviation in the loop, operates stably, and is maintenance-free and effective.
第１図は本発明に係る直流帰還型渦流距離計の
一実施例を示す構成図、第２図は第１図に示す距
離計の出力特性図、第３図は従来の渦流式距離計
の構成図、第４図は第３図に示す距離計の出力特
性図である。
１……渦流センサ、１−１……１次コイル、１
−２，１−３……２次コイル、２……発振器、４
……被測定体、１０……DC／AC変換回路、１１
……電力増幅器、１２……差動型信号増幅器、１
３……直流増幅器、１４……同期検波回路、１５
……直流基準電圧発生回路。
Fig. 1 is a configuration diagram showing an embodiment of a DC feedback type eddy current rangefinder according to the present invention, Fig. 2 is an output characteristic diagram of the rangefinder shown in Fig. 1, and Fig. 3 is a diagram of a conventional eddy current rangefinder. The configuration diagram, FIG. 4, is an output characteristic diagram of the distance meter shown in FIG. 3. 1...Eddy current sensor, 1-1...Primary coil, 1
-2, 1-3... Secondary coil, 2... Oscillator, 4
...Object to be measured, 10...DC/AC conversion circuit, 11
...Power amplifier, 12...Differential signal amplifier, 1
3... DC amplifier, 14... Synchronous detection circuit, 15
...DC reference voltage generation circuit.
Claims (1)
の交流信号が供給される１次コイルおよび各誘起
電圧の差電圧を出力する対なる２次コイルを有す
る渦流センサと、この渦流センサの２次コイルか
ら出力される電圧の差電圧を前記交流信号に同期
して検波し、直流信号として取り出す同期検波回
路と、この同期検波回路から出力される直流信号
を受け、この直流信号と予め設定された直流基準
信号とのレベル差を求めて前記渦流センサおよび
前記被測定体の間の距離に対応した信号を出力す
る差動増幅回路と、この差動増幅回路から出力さ
れる信号に応じて前記渦流センサの１次コイルに
供給される交流信号の電圧レベルを制御する供給
制御回路とを具備したことを特徴とする直流帰還
型渦流距離計。1. An eddy current sensor that is disposed close to the object to be measured and has a primary coil to which an alternating current signal of a predetermined frequency is supplied and a paired secondary coil that outputs a differential voltage between each induced voltage, and 2 of this eddy current sensor. A synchronous detection circuit that detects the voltage difference between the voltages output from the next coil in synchronization with the AC signal and extracts it as a DC signal, and a synchronous detection circuit that receives the DC signal output from this synchronous detection circuit, and a differential amplifier circuit that calculates a level difference between the eddy current sensor and the measured object and outputs a signal corresponding to the distance between the eddy current sensor and the measured object; A DC feedback type eddy current distance meter comprising a supply control circuit that controls the voltage level of an AC signal supplied to a primary coil of an eddy current sensor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20423484A JPS6182117A (en) | 1984-09-29 | 1984-09-29 | Direct current feedback type eddy current range finder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20423484A JPS6182117A (en) | 1984-09-29 | 1984-09-29 | Direct current feedback type eddy current range finder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6182117A JPS6182117A (en) | 1986-04-25 |
| JPH0334807B2 true JPH0334807B2 (en) | 1991-05-24 |
Family
ID=16487064
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20423484A Granted JPS6182117A (en) | 1984-09-29 | 1984-09-29 | Direct current feedback type eddy current range finder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6182117A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE463893B (en) * | 1987-09-28 | 1991-02-04 | Geotronics Ab | DEVICE FOR DETECTING THE LEVEL OF A BATTERY SURFACE OF A SMALL METAL BATH |
| US9587745B2 (en) | 2013-04-24 | 2017-03-07 | Eagle Industry Co., Ltd. | Sliding component |
| CN106225657B (en) * | 2016-08-12 | 2019-12-06 | 安徽容知日新科技股份有限公司 | displacement sensor |
| CN106969698A (en) * | 2017-06-02 | 2017-07-21 | 深圳怡化电脑股份有限公司 | A kind of electric vortex sensor measuring circuit and current vortex sensor |
-
1984
- 1984-09-29 JP JP20423484A patent/JPS6182117A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6182117A (en) | 1986-04-25 |
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