JPH0359480B2 - - Google Patents
Info
- Publication number
- JPH0359480B2 JPH0359480B2 JP24654884A JP24654884A JPH0359480B2 JP H0359480 B2 JPH0359480 B2 JP H0359480B2 JP 24654884 A JP24654884 A JP 24654884A JP 24654884 A JP24654884 A JP 24654884A JP H0359480 B2 JPH0359480 B2 JP H0359480B2
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- circuit
- alternating current
- resistor
- transmission lines
- 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
- 230000005540 biological transmission Effects 0.000 claims description 14
- 238000005070 sampling Methods 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 9
- 238000005259 measurement Methods 0.000 description 7
- 239000003990 capacitor Substances 0.000 description 3
- 230000001360 synchronised effect Effects 0.000 description 2
- 238000013480 data collection Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
Landscapes
- Arrangements For Transmission Of Measured Signals (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Description
【発明の詳細な説明】
〈技術分野〉
本発明は、遠隔地に設置されたセンサにより測
定データの収集を行う遠隔測定装置に関し、特
に、交流による測定しか許されない遠隔地の抵抗
値測定装置に適するものである。[Detailed Description of the Invention] <Technical Field> The present invention relates to a remote measuring device that collects measurement data using a sensor installed in a remote location, and is particularly applicable to a resistance value measuring device in a remote location where only AC measurement is allowed. It is suitable.
〈解決課題〉
例えばある種の湿度センサは直流電源を印加す
ると損傷或いは特性が変化するためめ、交流印加
しか許されない。このようなセンサを用いて遠隔
地の物理量を測定するには、通常第６図に示すよ
うに、センサ１の両端に２本の伝送線２，３を接
続し、この伝送線に電源装置４より交流の正弦波
を印加し、伝送線の電線ioを測定してセンサ１の
抵抗値Rxを求める方法が用いられる。<Problem to be solved> For example, some types of humidity sensors are damaged or their characteristics change when DC power is applied, so only AC power is allowed. To measure a physical quantity at a remote location using such a sensor, normally two transmission lines 2 and 3 are connected to both ends of the sensor 1, and a power supply 4 is connected to the transmission line, as shown in FIG. A method is used in which the resistance value Rx of the sensor 1 is determined by applying an AC sine wave and measuring the electric wire io of the transmission line.
しかし、測定点が遠隔地にあつて伝送線が長い
場合は、伝送線間容量Cxが存在するため、直流
測定のときのように単純なオームの法則から抵抗
値Rxを算出すると誤差を生じる。特にセンサの
抵抗値Rxが大きい場合には静電容量Cxの値が同
じであつても誤差は大きくなる。 However, if the measurement point is in a remote location and the transmission line is long, there will be a capacitance Cx between the transmission lines, so calculating the resistance value Rx from a simple Ohm's law as in direct current measurement will result in an error. In particular, when the resistance value Rx of the sensor is large, the error becomes large even if the value of the capacitance Cx is the same.
なお、静電容量Cxの値が既知の場合は、抵抗
値Rxを算出することができるが、通常は線間容
量Cxを正確に測定することは困難であり、かつ、
時刻とともに変動する。 Note that if the value of the capacitance Cx is known, the resistance value Rx can be calculated, but it is usually difficult to accurately measure the line capacitance Cx, and
Varies with time.
また、電源同期検波方法を用いれば精密な測定
をすることができるが、安定かつ低歪率の正弦波
電源が必要となるので装置が大型化し複雑になる
欠点がある。 Furthermore, although accurate measurements can be made using the power source synchronous detection method, it requires a stable, low-distortion sine wave power source, which has the drawback of increasing the size and complexity of the device.
〈発明の目的〉
本発明の目的は、遠隔地のセンサに対して２本
の伝送線により交流電源を印加しながら、浮遊容
量の影響を除去し、かつ、構成が簡単な遠隔測定
装置を提供することである。<Object of the Invention> An object of the present invention is to provide a remote measuring device that removes the influence of stray capacitance while applying AC power to a remote sensor through two transmission lines, and that has a simple configuration. It is to be.
〈発明の構成〉
本発明の遠隔測定装置は、第１図に示すよう
に、遠隔地に設置されたセンサ１の両端に接続さ
れる２本の伝送線２，３と、その２本の伝送線に
交流方形波を印加する交流電源手段５と、上記２
本の伝送線のいずれか一方に直列接続された抵抗
器６と、上記交流方形波と同期し、かつ、極性切
換後所定時間経過後における上記抵抗器の端子電
圧を取り出すサンプリング手段７を有する装置に
おいて、上記サンプリング手段７が、第３図およ
び第５図に示すように、抵抗器６の端子電圧を電
圧電流変換１７したのち全波整流１８し、その全
波整流の出力端子に負荷抵抗１９を接続してなる
回路を備えていることを特徴としている。<Configuration of the Invention> As shown in FIG. 1, the telemetry device of the present invention includes two transmission lines 2 and 3 connected to both ends of a sensor 1 installed at a remote location, AC power supply means 5 for applying an AC square wave to the line;
A device having a resistor 6 connected in series to either one of the main transmission lines, and a sampling means 7 that is synchronized with the AC square wave and extracts the terminal voltage of the resistor after a predetermined period of time has passed after polarity switching. As shown in FIGS. 3 and 5, the sampling means 7 performs voltage-current conversion 17 on the terminal voltage of the resistor 6, performs full-wave rectification 18, and connects a load resistor 19 to the output terminal of the full-wave rectification. It is characterized by having a circuit formed by connecting the .
このサンプリング手段７には、第２図ａに示す
ように、極性切換後所定時間t1経過後、次の極性
切換時までの間の信号をサンプリングする態様
と、第２図ｂに示すように、極性切換後所定時間
t2経過後の微小時間Δtの値をサンプルホールドす
る態様とがある。 As shown in FIG. 2a, this sampling means 7 has a mode in which the signal is sampled after a predetermined time t1 has elapsed after polarity switching and until the next polarity switching, as shown in FIG. 2b. , specified time after polarity switching
There is a mode in which the value of the minute time Δt after t 2 is sampled and held.
〈作用〉
一般に、定電圧信号をダイオードにて整流する
と順方向電圧分だけ出力電圧が降下してこれが測
定誤差の原因になるが、本発明においては、電圧
電流変換回路により電圧信号を一旦電流信号に変
換したのち全波整流しているのでダイオードによ
る影響がなく、負荷抵抗１９に検出される出力信
号の測定値が正確なものとなる。<Function> Generally, when a constant voltage signal is rectified by a diode, the output voltage drops by the forward voltage, which causes measurement errors. However, in the present invention, the voltage signal is converted into a current signal by a voltage-current conversion circuit. Since the full-wave rectification is performed after conversion to , there is no influence from the diode, and the measured value of the output signal detected by the load resistor 19 is accurate.
〈実施例〉 第３図に本発明の実施例の回路図を示す。<Example> FIG. 3 shows a circuit diagram of an embodiment of the present invention.
２個の直流電源１１，１２、単極性方形波発振
器１３、及び切換スイツチ１４が両極性方形波を
出力する交流電源手段１５を構成している。２本
の伝送線２，３の一方には電流ioを検出するため
の抵抗器６が接続され、この抵抗器６の端子電圧
が差動増幅器１６により取出され、電圧電流変換
回路１７により交流電流信号に変換され、ダイオ
ードD1，D2，D3，D4より成る全波整流回路１８
により全波整流され、この直流出力に負荷抵抗１
９が接続されて出力電圧υが取出される。整流回
路１８にはサンプリング用スイツチS1，S2が設け
られ、一方のスイツチS1は正極性コンパレータ２
０により開閉制御され、他方スイツチS2は負極性
コンパレータ２１により開閉制御される。一方、
交流電源手段１５の出力端子間にコンデンサＣと
抵抗Ｒの直列接続よりなるタイマー回路２２が接
続される。この回路２２の時定数は、センサ１の
抵抗Rxと浮遊容量Cxの時定数よりも大きく、且
つ、電源の方形波の半周期Ｔ／２よりも小さい値
に選ばれる。両コンパレータ２０，２１の入力端
子には、コンデンサＣの端子電圧υcが入力され、
正極性コンパレータ２０は正のレフアレンス電圧
＋VTHと入力電圧υcを比較し、負極性コンパレー
タ２１は負のレフアレンス電圧−VTHと入力電圧
υcを比較し、それぞれHi又はLoを出力する。電
圧電流変換回路１７の出力側に接続されている２
個のツエナーダイオードZDは、スイツチS1，S2が
いずれもオフのときに電流を逃がすための回路で
あつて、その両端子間電圧はほぼツエナー電圧
VzDとなる。電圧電流変換回路１７、全波整流回
路１８、コンパレータ２０，２１、及び、タイマ
ー回路２２がサンプリング手段７を構成してい
る。 Two DC power sources 11 and 12, a unipolar square wave oscillator 13, and a changeover switch 14 constitute an AC power source means 15 that outputs a bipolar square wave. A resistor 6 for detecting the current io is connected to one of the two transmission lines 2 and 3, and the terminal voltage of the resistor 6 is extracted by a differential amplifier 16, and converted into an alternating current by a voltage-current conversion circuit 17. A full-wave rectifier circuit 18 consisting of diodes D 1 , D 2 , D 3 , and D 4 is converted into a signal.
This DC output is full-wave rectified by a load resistance of 1
9 is connected and the output voltage υ is taken out. The rectifier circuit 18 is provided with sampling switches S 1 and S 2 , and one switch S 1 is connected to the positive polarity comparator 2.
The opening and closing of the switch S 2 is controlled by a negative polarity comparator 21 . on the other hand,
A timer circuit 22 consisting of a capacitor C and a resistor R connected in series is connected between the output terminals of the AC power supply means 15. The time constant of this circuit 22 is selected to be larger than the time constants of the resistance Rx and stray capacitance Cx of the sensor 1, and smaller than the half period T/2 of the square wave of the power supply. The terminal voltage υc of the capacitor C is input to the input terminals of both comparators 20 and 21,
The positive polarity comparator 20 compares the positive reference voltage +V TH and the input voltage υc, and the negative polarity comparator 21 compares the negative reference voltage -V TH and the input voltage υc, and outputs Hi or Lo, respectively. 2 connected to the output side of the voltage-current conversion circuit 17
The Zener diode Z D is a circuit for releasing current when both switches S 1 and S 2 are off, and the voltage between its terminals is approximately the Zener voltage.
It becomes Vz D. The voltage-current conversion circuit 17, the full-wave rectifier circuit 18, the comparators 20 and 21, and the timer circuit 22 constitute the sampling means 7.
第４図に各部の波形図を示す。 FIG. 4 shows waveform diagrams of each part.
交流電源手段１５の出力波形はａ図に示すよう
な両極性の方形波である。この電源からセンサ１
（抵抗値Rx）に流れる電流をiRｘ、浮遊容量Cxに
流れる電流をicxとすれば、電源から流出する電
流ioは、
io＝iRｘ＋icx …(1)
となるから、ｂ図に示すように極性切換時の初期
のみicxが突出したものとなる。また、コンデン
サＣの端子電圧υcはｃ図に示すように変化し、
この電圧υcがレフアレンス電圧＋VTHをこえたと
きコンパレータ２０の出力がｄ図に示すように
Hiとなり、電圧υcが負のレフアレンス電圧−VTH
よりも低くなつたときコンパレータ２１の出力が
ｅ図に示すようにHiになる。コンパレータ２０
の出力がHiのときスイツチS1がオンになり、ダ
イオードD1→抵抗R0→ダイオードD4の回路が導
通し、コンパレータ２１の出力がHiのときスイ
ツチS2がオンになり、ダイオードD3→抵抗R0→
ダイオードD2の回路が導通する。スイツチS1又
はS2がともにオフのときの全波整流回路１８の入
力電圧は、ｆ図に示すようにツエナーダイオード
の端子電圧により規定され、スイツチS1又はS2の
オン時は電圧電流変換回路１７の出力が表われ
る。このとき、ダイオードD1，D2，D3，D4の順
方向の電圧降下にかかわらず抵抗R0には電圧電
流変換回路１７の出力電流が供給され、その波形
はｇ図に示すように、ｂ図の切換初期の突出部分
が除去されている。 The output waveform of the AC power supply means 15 is a bipolar square wave as shown in Figure a. Sensor 1 from this power supply
If the current flowing through (resistance value Rx) is i R x and the current flowing through the stray capacitance Cx is icx, then the current io flowing out from the power supply is io = i R x + icx (1), so it is shown in figure b. As shown, icx becomes prominent only at the initial stage of polarity switching. Also, the terminal voltage υc of capacitor C changes as shown in diagram c,
When this voltage υc exceeds the reference voltage +V TH , the output of the comparator 20 becomes as shown in figure d.
becomes Hi, and the voltage υc becomes the negative reference voltage −V TH
When it becomes lower than , the output of the comparator 21 becomes Hi as shown in figure e. Comparator 20
When the output of comparator 21 is Hi, switch S 1 is turned on, and the circuit of diode D 1 → resistor R 0 → diode D 4 becomes conductive. When the output of comparator 21 is Hi, switch S 2 is turned on, and diode D 3 →Resistance R 0 →
The circuit of diode D 2 becomes conductive. When both switches S 1 and S 2 are off, the input voltage of the full-wave rectifier circuit 18 is determined by the terminal voltage of the Zener diode, as shown in figure f, and when switch S 1 or S 2 is on, voltage-current conversion is performed. The output of circuit 17 appears. At this time, the output current of the voltage-current conversion circuit 17 is supplied to the resistor R 0 regardless of the voltage drop in the forward direction of the diodes D 1 , D 2 , D 3 , and D 4 , and its waveform is as shown in figure g. , b The protruding portion at the initial stage of switching has been removed.
このようにしてサンプリングされた電流値には
極性切換直後の突出部分が含まれていないので、
オームの法則通り、式
Rx＝υo／io …(2)
よりセンサ抵抗Rxを算出することができる。 The current value sampled in this way does not include the protruding part immediately after polarity switching, so
According to Ohm's law, the sensor resistance Rx can be calculated from the formula Rx=υo/io (2).
第５図に本発明の他の実施例を示す。この実施
例が前術のものと相違している点は、差動増幅器
１６の後段にサンプルホールド回路２３を設け、
方形波発振器１３の立上り及び立下りと同期して
作動する遅延回路２４を設けてサンプルホールド
回路２３を制御していることである。この実施例
ではコンパレータ２０，２１、タイマー回路２
２、スイツチS1，S2、ツエナーダイオードZDが不
要となる。 FIG. 5 shows another embodiment of the invention. This embodiment is different from the previous embodiment in that a sample and hold circuit 23 is provided after the differential amplifier 16.
A delay circuit 24 that operates in synchronization with the rise and fall of the square wave oscillator 13 is provided to control the sample and hold circuit 23. In this embodiment, comparators 20 and 21, a timer circuit 2
2. Switches S 1 and S 2 and Zener diode Z D become unnecessary.
〈効果〉
本発明によれば、交流による測定しか許さない
遠隔地のセンサに対し、交流に起因するケーブル
線間の浮遊容量の影響を除去し抵抗成分Rxのみ
の測定を行うことができる。しかも、遠隔地のセ
ンサとデータ収集点を結ぶケーブルはわずかに２
本で足り、従前の伝送線をそのまま利用して実施
することができる。<Effects> According to the present invention, it is possible to remove the influence of stray capacitance between cable lines caused by alternating current and measure only the resistance component Rx for a remote sensor that only allows measurement using alternating current. Moreover, only two cables are needed to connect the remote sensor and the data collection point.
A book is sufficient and the existing transmission line can be used as is.
第１図は本発明の構成を示すブロツク図、第２
図は本発明の作用説明図、第３図は本発明実施例
を示す回路図、第４図は第３図実施例の作用説明
図、第５図は本発明の他の実施例を示す回路図、
第６図は従来例を示す図である。
１…センサ、２，３…伝送線５…交流電源手
段、６…抵抗器、７…サンプリング手段、１７…
電圧電流変換回路、１８…全波整流回路、１９…
負荷抵抗、２０，２１…コンパレータ、２２…タ
イマー回路、２４…遅延回路。
Figure 1 is a block diagram showing the configuration of the present invention, Figure 2 is a block diagram showing the configuration of the present invention.
3 is a circuit diagram showing an embodiment of the present invention, FIG. 4 is a diagram illustrating the action of the embodiment in FIG. 3, and FIG. 5 is a circuit diagram showing another embodiment of the present invention. figure,
FIG. 6 is a diagram showing a conventional example. DESCRIPTION OF SYMBOLS 1...Sensor, 2, 3...Transmission line 5...AC power supply means, 6...Resistor, 7...Sampling means, 17...
Voltage-current conversion circuit, 18...Full-wave rectifier circuit, 19...
Load resistance, 20, 21... Comparator, 22... Timer circuit, 24... Delay circuit.
Claims (1)
る２本の伝送線と、その２本の伝送線に交流方形
波を印加する交流電流手段と、上記２本の伝送線
のいずれか一方に直列接続された抵抗器と、上記
交流方形波と同期し、かつ、極性切換後所定時間
経過後における上記抵抗器の端子電圧を取り出す
サンプリング手段を有する装置において、上記サ
ンプリング手段が、上記抵抗器の端子電圧を電圧
電流交換したのち全波整流し、その全波整流の出
力端子に負荷抵抗を接続してなる回路を備えてい
ることを特徴とする遠隔測定装置。1. Two transmission lines connected to both ends of a sensor installed in a remote location, an alternating current means for applying an alternating current square wave to the two transmission lines, and an alternating current means for applying an alternating current square wave to one of the two transmission lines. In an apparatus comprising resistors connected in series and sampling means for extracting the terminal voltage of the resistor in synchronization with the AC square wave and after a predetermined period of time has passed after polarity switching, the sampling means 1. A remote measuring device comprising a circuit in which a terminal voltage is subjected to full-wave rectification after voltage-current exchange, and a load resistor is connected to the output terminal of the full-wave rectification.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24654884A JPS61123998A (en) | 1984-11-21 | 1984-11-21 | Telemetering apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24654884A JPS61123998A (en) | 1984-11-21 | 1984-11-21 | Telemetering apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61123998A JPS61123998A (en) | 1986-06-11 |
| JPH0359480B2 true JPH0359480B2 (en) | 1991-09-10 |
Family
ID=17150049
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24654884A Granted JPS61123998A (en) | 1984-11-21 | 1984-11-21 | Telemetering apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61123998A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002006842A2 (en) * | 2000-07-13 | 2002-01-24 | Siemens Aktiengesellschaft | Circuit for determining the internal resistance of a linear lambda probe |
-
1984
- 1984-11-21 JP JP24654884A patent/JPS61123998A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61123998A (en) | 1986-06-11 |
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|---|---|---|---|
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