JPH043801B2 - - Google Patents
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- Publication number
- JPH043801B2 JPH043801B2 JP20424284A JP20424284A JPH043801B2 JP H043801 B2 JPH043801 B2 JP H043801B2 JP 20424284 A JP20424284 A JP 20424284A JP 20424284 A JP20424284 A JP 20424284A JP H043801 B2 JPH043801 B2 JP H043801B2
- Authority
- JP
- Japan
- Prior art keywords
- eddy current
- voltage
- phase
- signal
- output
- 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
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- 230000010363 phase shift Effects 0.000 claims description 15
- 238000001514 detection method Methods 0.000 claims description 13
- 230000001360 synchronised effect Effects 0.000 claims description 12
- 239000003990 capacitor Substances 0.000 claims description 5
- 239000000284 extract Substances 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 description 11
- 238000010586 diagram Methods 0.000 description 9
- 230000003321 amplification Effects 0.000 description 3
- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
Landscapes
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
Description
【発明の詳細な説明】 〔発明の技術分野〕 本発明は、渦流式距離計の改良に関する。[Detailed description of the invention] [Technical field of invention] The present invention relates to improvements in eddy current distance meters.
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４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とから構成され、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、前記
交流信号が渦流センサ１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。この渦電流により、被測定体４から
は１次コイル１−１に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にはそれぞれ
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、２次コイル１−２，１−３から差分の電
圧が発生され、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. 4 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, and the primary coil 1-1 has an oscillator. An alternating current signal of a predetermined frequency outputted from the amplifier 2 is supplied via an amplifier 3. This eddy current sensor 1 is placed close to an object 4 to be measured such as a rolled metal plate or molten metal liquid, and when the AC signal is supplied to the eddy current sensor 1, an AC magnetic field is generated from the primary coil 1-1. Measured object 4
This causes an eddy current to occur 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 magnetic field crossing the secondary coils 1-2, 1-3 changes, and voltages of different values are induced in each of the secondary coils 1-2, 1-3. Here, since the influence of magnetic field changes due to eddy currents is greater on the side of the secondary coil 1-2 which is closer to the object to be measured 4, the differential voltage from the secondary coils 1-2 and 1-3 is 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. At this time, the output voltage of amplifier 3 e put
is 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・eio／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
ズである。 e put = −G 1・e io /1−G 1・G 2・K = −G 1・e io /1−G 1・G 2 (e put /Zp) (M 1 −M 2 )…
...(1) In addition, G 1 is the open amplification degree of the amplifier 3, e io is the output voltage of the oscillator 2, G 2 is the amplification degree of the signal amplifier 5, Zp is the impedance of the primary coil 1-1,
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 /Zp), 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.
渦流センサ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 eddy current sensor 1 and the main body of the device, that is, the amplifier 3 and the signal amplifier 5, and variations 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５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 5. 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、位相偏位を補償して発
振現象をなくし得、安定に動作しかつ高精度な渦
流式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 an eddy current distance meter that can compensate for phase deviations and eliminate oscillation phenomena, operates stably, and has high accuracy.
本発明は、被測定体上に配置され、発振器の交
流出力信号が第１の増幅回路を介して供給される
１次コイルおよび１対のコイルから成る２次コイ
ルから構成される渦流センサの２次コイルの各コ
イルに誘起する電圧のいずれか一方を移相する、
すなわち２次コイルの各誘起電圧の差電圧を前記
交流出力信号を所定位相だけ移相させた信号によ
り同期検波し、この同期検波により前記差電圧に
含まれる位相偏位成分を直流信号として取り出
し、移相制御手段がこの直流信号を受けてその電
圧値に応じて静電容量を可変し、前記２次コイル
に誘起する電圧のいずれか一方を移相して前記位
相偏位成分を補償するようにした渦流式距離計で
ある。
The present invention provides an eddy current sensor consisting of a primary coil placed on an object to be measured and to which an AC output signal of an oscillator is supplied via a first amplifier circuit, and a secondary coil consisting of a pair of coils. Shifting the phase of one of the voltages induced in each coil of the next coil,
That is, the differential voltage between the respective induced voltages of the secondary coil is synchronously detected using a signal obtained by shifting the AC output signal by a predetermined phase, and the phase deviation component included in the differential voltage is extracted as a DC signal by this synchronous detection, A phase shift control means receives the DC signal and varies the capacitance according to the voltage value thereof, and shifts the phase of one of the voltages induced in the secondary coil to compensate for the phase deviation component. It is an 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図は本発明の渦流式距離計の構
成図である。第１図において１０は渦流センサで
あつて、この渦流センサ１０は一定振幅で所定周
波数の交流信号が供給される１次コイル１０−１
と、この１次コイルに近接配置された対なる２次
コイル１０−２，１０−３とから構成されてい
る。なお、２次コイルの各コイル１０−２，１０
−３は、同一巻数となつている。具体的に１次コ
イル１０−１には、発振器１１の出力端が第１の
増幅器１２を介して接続され、一方の２次コイル
１０−２は第２の増幅器としての信号増幅器１３
の負入力端子に接続され、他方の２次コイル１０
−３は移相制御手段としての電圧−容量変換回路
１４を介して信号増幅器１３の正入力端子に接続
されている。そして、信号増幅器１３の出力端子
が第１の増幅器１２の正入力端子に接続されて帰
還がかけられる構成となつている。
An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an eddy current distance meter according to the present invention. In FIG. 1, 10 is an eddy current sensor, and this eddy current sensor 10 has a primary coil 10-1 to which an alternating current signal with a constant amplitude and a predetermined frequency is supplied.
and a pair of secondary coils 10-2 and 10-3 arranged close to this primary coil. In addition, each coil 10-2, 10 of the secondary coil
-3 has the same number of turns. Specifically, the output end of an oscillator 11 is connected to the primary coil 10-1 via a first amplifier 12, and one secondary coil 10-2 is connected to a signal amplifier 13 as a second amplifier.
is connected to the negative input terminal of the other secondary coil 10.
-3 is connected to the positive input terminal of the signal amplifier 13 via a voltage-capacitance conversion circuit 14 as a phase shift control means. The output terminal of the signal amplifier 13 is connected to the positive input terminal of the first amplifier 12 to apply feedback.
１５は発振器１１から出力される交流信号を90
度移相して出力する移相回路であつて、その出力
信号は同期検波回路１６に送られるようになつて
いる。この同期検波回路１６は、信号増幅器１３
から出力される２次コイル１０−２，１０−２の
各誘起電圧の差電圧を、移相回路１５により移相
された発振器１１から出力される交流信号に同期
して検波し、差電圧に含まれる位相偏位成分を直
流信号として取り出すものである。そうして、こ
の同期検波回路１０から出力される直流信号は、
直流増幅回路１７を介して前記電圧−容量変換回
路１４に送られるようになつている。 15 is the AC signal output from the oscillator 11.
It is a phase shift circuit which shifts the phase by a degree and outputs the signal, and its output signal is sent to the synchronous detection circuit 16. This synchronous detection circuit 16 includes a signal amplifier 13
The differential voltage between the induced voltages of the secondary coils 10-2 and 10-2 outputted from the secondary coils 10-2 and 10-2 is detected in synchronization with the AC signal outputted from the oscillator 11 whose phase has been shifted by the phase shift circuit 15, and the differential voltage is detected. The included phase deviation component is extracted as a DC signal. Then, the DC signal output from this synchronous detection circuit 10 is
The signal is sent to the voltage-capacitance conversion circuit 14 via the DC amplifier circuit 17.
さて、この電圧−容量変換回路１４は、同期検
波回路１６から出力される直流信号を受け、この
直流信号の電圧値に応じて自身の回路内に接続さ
れた静電容量が変化し、この変化に応じて２次コ
イル１０−３の誘起電圧の位相をずらして信号増
幅器１３の非反転入力端子に送出する機能をもつ
たものである。具体的には第２図に示すような構
成となつている。すなわち、入力端子Yioと出力
端子outとの間にコンデンサC0が接続された掛算
器１４−１が、入力端子Yioがコイル１０−３に
接続され、出力端子outがコンデンサC0を介して
信号増幅器１３の非反転入力端子に接続された構
成となつている。なお、同期検波回路１６から出
力される直流信号は掛算器１４−１の入力端子
Xioに入力するようになつている。掛算器１４−
１の入力端子Yioとコイル１０−３との間に抵抗
Ｒ１が接続されるとともに入力端子Yioに抵抗Ｒ
２が接続されて接地されている。また、信号増幅
器１３の反転入力端子と出力端子およびコイル１
０−２との間にはそれぞれ抵抗Ｒ３，Ｒ４が接続
されている。 Now, this voltage-capacitance conversion circuit 14 receives the DC signal output from the synchronous detection circuit 16, and changes the capacitance connected within its own circuit according to the voltage value of this DC signal. It has a function of shifting the phase of the induced voltage of the secondary coil 10-3 according to the voltage and transmitting it to the non-inverting input terminal of the signal amplifier 13. Specifically, the configuration is as shown in FIG. That is, the multiplier 14-1 has a capacitor C0 connected between the input terminal Yio and the output terminal out, the input terminal Yio is connected to the coil 10-3, and the output terminal out is connected to the coil 10-3 through the capacitor C0 . and is connected to the non-inverting input terminal of the signal amplifier 13. Note that the DC signal output from the synchronous detection circuit 16 is input to the input terminal of the multiplier 14-1.
It is designed to be input to X io . Multiplier 14-
A resistor R1 is connected between the input terminal Y io of 1 and the coil 10-3, and a resistor R1 is connected to the input terminal Y io of the coil 10-3.
2 is connected and grounded. In addition, the inverting input terminal and output terminal of the signal amplifier 13 and the coil 1
0-2, resistors R3 and R4 are connected respectively.
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１０が被測定体Ｓ例えば
圧延板や溶解液などの上部に置かれ、この渦流セ
ンサ１０の１次コイル１０−１に発振器１１から
出力される交流信号が第１の増幅器１２を介して
供給されると、１次コイル１０−１からは交流磁
界が発生しこの交流磁界が被測定体Ｓと交差す
る。すると、被測定体Ｓ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１０−１により発
生し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次コイルの各コ
イル１０−２，１０−３と交差する交流磁界が変
化し、その変化量は被測定体Ｓに近い側のコイル
１０−２に対して大きくなる。したがつて、２次
コイルの各コイル１０−２，１０−３に誘起する
電圧はそれぞれ異なつた値となる。ここで、２次
コイルのコイル１０−２の誘起電圧をeS1、コイ
ル１０−３の誘起電圧をeS2とすると、信号増幅
器１３からは（eS2−eS1）G13なる差電圧が出力さ
れる。なお、G13は信号増幅器１３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 10 is placed above an object S to be measured, such as a rolled plate or a solution, and an alternating current signal outputted from an oscillator 11 to a primary coil 10-1 of this eddy current sensor 10 is transmitted through a first amplifier 12. When supplied, an alternating magnetic field is generated from the primary coil 10-1, and this alternating magnetic field intersects the object S to be measured. Then, an eddy current is generated on the surface of the object to be measured S, and this eddy current generates a magnetic field that acts as a reaction to the alternating current magnetic field generated by the primary coil 10-1. Due to the reaction of this magnetic field, the alternating current magnetic field that intersects each coil 10-2, 10-3 of the secondary coil changes, and the amount of change becomes larger for the coil 10-2 closer to the object S to be measured. Therefore, the voltages induced in each of the secondary coils 10-2 and 10-3 have different values. Here, if the induced voltage of the secondary coil 10-2 is e S1 and the induced voltage of the coil 10-3 is e S2 , the signal amplifier 13 outputs a differential voltage of (e S2 − e S1 ) G 13 . be done. Note that G 13 is the amplification degree of the signal amplifier 13.
一方、移相回路１５は発振器１１から出力され
る交流信号を90度移相して同期検波回路１６に出
力している。そこで、同期検波回路１６は、移相
回路１５からの移相された交流信号に同期して信
号増幅器１３から出力される差電圧を検波し、差
電圧に含まれる位相偏位成分に応じた直流信号を
出力する。この直流信号は直流増幅回路１７を介
して電圧−容量変換回路１４の掛算器１４−１に
入力する。 On the other hand, the phase shift circuit 15 shifts the phase of the AC signal output from the oscillator 11 by 90 degrees and outputs it to the synchronous detection circuit 16. Therefore, the synchronous detection circuit 16 detects the difference voltage output from the signal amplifier 13 in synchronization with the phase-shifted AC signal from the phase shift circuit 15, and detects the DC signal according to the phase deviation component included in the difference voltage. Output a signal. This DC signal is input to the multiplier 14-1 of the voltage-capacitance conversion circuit 14 via the DC amplifier circuit 17.
これにより、２次コイルのコイル１０−３と信
号増幅器１３の非反転入力端子との間に介存する
実質的な静電容量が、掛算器１４−１に入力した
直流信号の電圧値に応じて変化する。つまり、直
流信号の電圧値をVxとすると、等価静電容量Ce
は次式により表わされる。すなわち
Ce＝Cp（１＋0.1Vx）〔Ｆ〕 …(2)
である。このように等価静電容量Ceが変化する
ことによりコイル１０−３の誘起電圧eS2は、差
電圧に含まれる位相偏位成分に応じて移相されて
信号増幅器１３の非反転入力端子に送られる。し
たがつて、２次コイルの各誘起電圧間に位相ずれ
が生じても、この位相ずれが自動的に補償される
ことになる。そうして、信号増幅器１３から出力
される差電圧が第１の増幅器１２の非反転入力端
子に加わることにより、第１の増幅器１２からは
渦流センサ１と被測定体Ｓとの距離に応じた電圧
信号e0が出力される。第３図は第１図に示す距離
計の渦流センサ１０を温度20℃，60℃の条件のも
とで試験を行ない、この結果得られた出力特性図
である。なお、渦流センサ１０にはコイル径30mm
φのものが用いられている。この出力特性図から
判るように温度60℃の条件で補償が行なわれない
と温度20℃の条件での出力特性と異なつたものと
なるが、補償を行なうと温度20℃の出力特性と同
一になつている。したがつて、温度が変化しても
第１図に示す距離計の出力特性は変化せず、距離
ｌに応じた出力電圧が得られる。 As a result, the substantial capacitance that exists between the coil 10-3 of the secondary coil and the non-inverting input terminal of the signal amplifier 13 increases depending on the voltage value of the DC signal input to the multiplier 14-1. Change. In other words, if the voltage value of the DC signal is V x , then the equivalent capacitance C e
is expressed by the following equation. That is, C e =C p (1+0.1V x ) [F]...(2). As the equivalent capacitance C e changes in this way, the induced voltage e S2 of the coil 10-3 is phase-shifted according to the phase deviation component included in the differential voltage, and is applied to the non-inverting input terminal of the signal amplifier 13. Sent. Therefore, even if a phase shift occurs between the induced voltages of the secondary coils, this phase shift is automatically compensated for. Then, by applying the differential voltage output from the signal amplifier 13 to the non-inverting input terminal of the first amplifier 12, the first amplifier 12 outputs a signal corresponding to the distance between the eddy current sensor 1 and the object to be measured S. A voltage signal e0 is output. FIG. 3 is an output characteristic diagram obtained as a result of testing the eddy current sensor 10 of the distance meter shown in FIG. 1 under conditions of temperatures of 20° C. and 60° C. Note that the eddy current sensor 10 has a coil diameter of 30 mm.
φ is used. As can be seen from this output characteristic diagram, if no compensation is performed at a temperature of 60°C, the output characteristics will be different from those at a temperature of 20°C, but if compensation is performed, the output characteristics will be the same as at a temperature of 20°C. It's summery. Therefore, even if the temperature changes, the output characteristics of the distance meter shown in FIG. 1 do not change, and an output voltage corresponding to the distance l can be obtained.
このように本発明の距離計においては、２次コ
イルのコイル１０−３と信号増幅器１３の非反転
入力端子との間に電圧−容量変換回路１４を設
け、この電圧−容量変換回路１４により同期検波
回路１６からの位相偏位成分に応じた直流信号に
応じてコイル１０−３の誘起電圧を移相して位相
偏位成分を補償するようにしたので、渦流センサ
１０の周囲温度が変化して２次コイルの各コイル
１０−２，１０−３のインピーダンスがアンバラ
ンスとなり各誘起電圧間に位相偏位が生じてもこ
の位相偏位が自動的に補償され、渦流センサ１０
と被測定体Ｓとの距離に応じた正確な出力電圧が
得られ測定精度が向上する。これにより、出力電
圧が誤差を含んだものとなつたり、自己発振する
ようなこともなく、回路の動作が安定する。そし
て、各回路の調整が非常に簡単になる。 In this way, in the distance meter of the present invention, the voltage-capacitance conversion circuit 14 is provided between the coil 10-3 of the secondary coil and the non-inverting input terminal of the signal amplifier 13, and the voltage-capacitance conversion circuit 14 performs synchronization. Since the induced voltage of the coil 10-3 is phase-shifted in accordance with the DC signal corresponding to the phase deviation component from the detection circuit 16 to compensate for the phase deviation component, the ambient temperature of the eddy current sensor 10 does not change. Even if the impedance of each coil 10-2, 10-3 of the secondary coil is unbalanced and a phase deviation occurs between each induced voltage, this phase deviation is automatically compensated for, and the eddy current sensor 10
An accurate output voltage corresponding to the distance between the object S and the object S to be measured can be obtained, and measurement accuracy is improved. This prevents the output voltage from containing errors or self-oscillation, and stabilizes the operation of the circuit. And adjustment of each circuit becomes very easy.
したがつて、被測定体Ｓが例えば溶解液であつ
て、渦流センサ１０の周囲温度が変化しても、こ
の溶解液と渦流センサ１０との距離を精度高く測
定できる。 Therefore, even if the object to be measured S is a solution, for example, and the ambient temperature of the eddy current sensor 10 changes, the distance between the solution and the eddy current sensor 10 can be measured with high accuracy.
本発明によれば、渦流センサの１対のコイルか
らなる２次コイルのいずれか一方のコイルと２次
コイルの各誘起電圧の差電圧を出力する第２の増
幅回路との間に移相制御手段を設け、この移相制
御手段により一方のコイルの誘起電圧を、差電圧
に含まれる位相偏位成分に応じた直流信号により
移相するようにしたので、位相偏位を補償して発
振現象をなくし得、安定に動作する高精度な渦流
式距離計を提供できる。
According to the present invention, phase shift control is performed between one of the secondary coils of the pair of coils of the eddy current sensor and the second amplifier circuit that outputs the voltage difference between the induced voltages of the secondary coils. This phase shift control means causes the phase of the induced voltage in one coil to be shifted by a DC signal corresponding to the phase deviation component included in the differential voltage, thereby compensating for the phase deviation and suppressing the oscillation phenomenon. It is possible to provide a highly accurate eddy current distance meter that operates stably.
第１図は本発明に係る渦流式距離計の一実施例
を示す構成図、第２図は第１図に示す距離計にお
ける電圧−容量変換回路の具体的な構成図、第３
図は第１図に示す距離計の出力特性図、第４図は
従来の渦流式距離計の構成図、第５図は第４図に
示す距離計の出力特性図である。
１０…渦流センサ、１０−１…１次コイル、１
０−２，１０−３…２次コイルの各コイル、１１
…発振器、１２…第１の増幅器、１３…信号増幅
器、１４…電圧−容量変換回路、１４−１…掛算
器、C0…コンデンサ、１５…移相回路、１６…
同期検波回路、１７…直流増幅回路、Ｓ…被測定
体。
FIG. 1 is a block diagram showing an embodiment of an eddy current rangefinder according to the present invention, FIG. 2 is a specific block diagram of a voltage-capacitance conversion circuit in the rangefinder shown in FIG. 1, and FIG.
1 is an output characteristic diagram of the distance meter shown in FIG. 1, FIG. 4 is a configuration diagram of a conventional eddy current distance meter, and FIG. 5 is an output characteristic diagram of the distance meter shown in FIG. 4. 10... Eddy current sensor, 10-1... Primary coil, 1
0-2, 10-3...Each coil of secondary coil, 11
...Oscillator, 12...First amplifier, 13...Signal amplifier, 14...Voltage-capacitance conversion circuit, 14-1...Multiplier, C0 ...Capacitor, 15...Phase shift circuit, 16...
Synchronous detection circuit, 17... DC amplifier circuit, S... object to be measured.
Claims (1)
号が第１の増幅回路を介して供給される１次コイ
ルおよび１対のコイルから成る２次コイルから構
成される渦流センサと、前記発振器の交流出力信
号を所定位相だけ移相する移相回路と、前記渦流
センサの２次コイルの各コイルに誘起する各電圧
の差電圧を求め、この差電圧を前記第１の増幅回
路に帰還する第２の増幅回路と、この第２の増幅
回路から出力される差電圧を前記移相回路により
移相された交流出力信号により同期検波し、前記
差電圧に含まれる位相偏位成分を直流信号として
取り出す同期検波回路と、前記渦流センサの２次
コイルのいずれか一方のコイルと前記第２の増幅
回路との間に設けられ、前記同期検波回路から出
力される直流信号の電圧値に応じて静電容量が可
変し、前記いずれか一方のコイルの誘起電圧の位
相を制御する移相制御手段とを具備したことを特
徴とする渦流式距離計。 ２ 移相制御手段は、一方の入力端に同期検波回
路の出力端が接続され、他方の入力端と出力端と
の間にコンデンサが接続され、かつ前記他方の入
力端に渦流センサの２次コイルのいずれか一方の
コイルが接続されるとともに前記出力端に前記コ
ンデンサを介して第２の増幅回路の入力端が接続
された掛算器を有する特許請求の範囲第１項記載
の渦流式距離計。[Claims] 1. Eddy current consisting of a primary coil placed on the object to be measured and to which an alternating current output signal of an oscillator is supplied via a first amplifier circuit, and a secondary coil consisting of a pair of coils. A voltage difference between the voltages induced in the sensor, a phase shift circuit that shifts the AC output signal of the oscillator by a predetermined phase, and each of the secondary coils of the eddy current sensor is calculated, and this difference voltage is applied to the first voltage. A second amplifier circuit that feeds back to the amplifier circuit and a differential voltage output from the second amplifier circuit are synchronously detected using an AC output signal whose phase has been shifted by the phase shift circuit, and the phase deviation included in the differential voltage is detected. a synchronous detection circuit that extracts the phase component as a DC signal; and a synchronous detection circuit that is provided between one of the secondary coils of the eddy current sensor and the second amplifier circuit, and is provided between one of the secondary coils of the eddy current sensor and the second amplifier circuit; An eddy current distance meter characterized by comprising: phase shift control means whose capacitance is variable according to a voltage value and which controls the phase of the induced voltage of one of the coils. 2. The phase shift control means has one input end connected to the output end of the synchronous detection circuit, a capacitor connected between the other input end and the output end, and the second input end connected to the secondary output end of the eddy current sensor. The eddy current distance meter according to claim 1, further comprising a multiplier to which one of the coils is connected and an input end of a second amplifier circuit is connected to the output end via the capacitor. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20424284A JPS6182102A (en) | 1984-09-29 | 1984-09-29 | Eddy current distance meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20424284A JPS6182102A (en) | 1984-09-29 | 1984-09-29 | Eddy current distance meter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6182102A JPS6182102A (en) | 1986-04-25 |
| JPH043801B2 true JPH043801B2 (en) | 1992-01-24 |
Family
ID=16487200
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20424284A Granted JPS6182102A (en) | 1984-09-29 | 1984-09-29 | Eddy current distance meter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6182102A (en) |
-
1984
- 1984-09-29 JP JP20424284A patent/JPS6182102A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6182102A (en) | 1986-04-25 |
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