JPS6146778B2 - - Google Patents
Info
- Publication number
- JPS6146778B2 JPS6146778B2 JP12584980A JP12584980A JPS6146778B2 JP S6146778 B2 JPS6146778 B2 JP S6146778B2 JP 12584980 A JP12584980 A JP 12584980A JP 12584980 A JP12584980 A JP 12584980A JP S6146778 B2 JPS6146778 B2 JP S6146778B2
- Authority
- JP
- Japan
- Prior art keywords
- moisture
- current
- voltage
- circuit
- measuring device
- 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
- 238000006243 chemical reaction Methods 0.000 claims description 9
- 238000005259 measurement Methods 0.000 claims description 7
- 238000010586 diagram Methods 0.000 description 5
- 241000209140 Triticum Species 0.000 description 3
- 235000021307 Triticum Nutrition 0.000 description 3
- 235000013339 cereals Nutrition 0.000 description 3
- 238000000034 method Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/048—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance for determining moisture content of the material
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/005—Circuits for altering the indicating characteristic, e.g. making it non-linear
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Nonlinear Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Description
【発明の詳細な説明】
本発明は、木材、穀物、特に麦等の試料に含有
する水分を試料の電気抵抗値と相関関係を有する
ことを利用して測定するための電気抵抗式水分計
に関し、特に試料の水分が10％程度から40％程度
までの広範囲に及ぶ場合に、高水分側と低水分側
とで手動スイツチで切換えることなく自動的に全
範囲を測定できる広帯域自動水分計に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrical resistance moisture meter for measuring moisture contained in samples such as wood, grain, particularly wheat, by utilizing the correlation with the electrical resistance value of the sample. In particular, this invention relates to a wide-band automatic moisture analyzer that can automatically measure the entire range without switching between the high moisture side and the low moisture side with a manual switch, especially when the moisture content of the sample ranges over a wide range from about 10% to about 40%.
従来の電気抵抗式水分計では、試料に流れる電
流を直接対数変換している。例えば第１図に示す
ような水分測定回路が一般に知られている。そこ
では試料ＲXに直列にダイオードD1，D2を接続
し、ダイオードの順方向電圧の対数特性と穀物に
含まれる水分対電気抵抗の対数特性を合成した出
力Voutを得、それによつて水分率表示を直線特
性としている。しかしながら、この方式では水分
率が30％以上の高水分域になると試料に電流が流
れすぎて、その電流を対数変換すると出力が飽和
してしまうばかりでなく、ダイオードD1，D2に
流入する電流によるジユール熱発生の影響が測定
出力に及んでくる。 In conventional electrical resistance moisture meters, the current flowing through the sample is directly logarithmically converted. For example, a moisture measuring circuit as shown in FIG. 1 is generally known. Here, diodes D 1 and D 2 are connected in series with the sample R The rate display is a linear characteristic. However, with this method, when the moisture content reaches a high moisture range of 30% or more, too much current flows through the sample, and when that current is converted logarithmically, not only does the output become saturated, but it also flows into the diodes D1 and D2. The measurement output is affected by the generation of Joule heat due to the current.
第２図は上記の欠点をなくした広帯域水分計の
測定回路であり、本出願人の昭和54年３月８日出
願の特願昭54−27206号に開示されたものであ
る。第２図では、試料ＲXに流れる電流Ｉを、演
算増幅器IC1を用い、その負荷抵抗R2と負帰還抵
抗R1とに分流させることにより、試料電流に比
例した電流I2を取り出し、その電流を演算増幅器
IC2、ダイオードD1，D2を含む対数変換回路３に
よつて電流・電圧対数変換することによつて、高
水分域でも高精度で水分率表示電圧値の直線化が
図かれるようにしている。対数変換回路３の出力
は演算回路４によつて水分値演算や温度補償演算
され、その結果はメータＭによつて水分率として
表示される。この回路においても、低水分域とな
ると演算増幅器のオフセツト電圧や温度ドリフト
などの影響で水分の測定が難かしくなつてくる。
これは低水分域では、試料ＲXに流れる電流が
100nA程度となるが、高水分域での分流の必要性
から負帰還抵抗R1を200Ωとしなければならない
からである。 FIG. 2 shows a measurement circuit for a broadband moisture meter which eliminates the above-mentioned drawbacks, and is disclosed in Japanese Patent Application No. 1983-27206, filed on March 8, 1982 by the present applicant. In FIG. 2, a current I flowing through the sample Rx is shunted to its load resistor R2 and negative feedback resistor R1 using an operational amplifier IC1 , and a current I2 proportional to the sample current is extracted. The current is converted into an operational amplifier.
The logarithmic conversion circuit 3 including IC 2 and diodes D 1 and D 2 performs logarithmic conversion of current and voltage, so that the moisture content display voltage value can be linearized with high precision even in high moisture areas. There is. The output of the logarithmic conversion circuit 3 is subjected to moisture value calculation and temperature compensation calculation by an arithmetic circuit 4, and the results are displayed by a meter M as a moisture percentage. Even in this circuit, in a low moisture range, it becomes difficult to measure moisture due to the effects of the offset voltage of the operational amplifier, temperature drift, etc.
This means that in a low moisture region, the current flowing through sample R
Although it is about 100 nA, the negative feedback resistor R 1 must be set to 200 Ω due to the necessity of shunting in a high moisture region.
従つて、本発明の目的は上記問題点を解決する
ことであり、低水分領域から高水分領域に至るま
で、手動切換動作なしに、自動的に水分測定がで
きるようにした広帯域電気抵抗式水分計を提供す
ることにある。 Therefore, an object of the present invention is to solve the above-mentioned problems, and to provide a wide-band electrical resistance moisture measurement system that can automatically measure moisture content from low moisture areas to high moisture areas without manual switching operations. The aim is to provide a meter.
本発明の基本的概念は試料に流れる電流を低水
分領域では分流せずに直接対数変換し、高水分領
域ではアナログスイツチにより分流回路を通して
から対数変換を行ない、その分流水分信号により
自動的にアナログスイツチの切換えを行なうこと
により広範囲にわたる試料水分を測定できるよう
にしたものである。 The basic concept of the present invention is to directly logarithmically convert the current flowing through the sample in low moisture regions without dividing it, and in high moisture regions, logarithmically convert the current through a shunt circuit using an analog switch. By switching the switch, it is possible to measure the moisture content of a wide range of samples.
以下本発明の実施例を図面を参照して説明す
る。第３図は本発明による電気抵抗式水分計の測
定回路を示す。図中発振器１は直流又は交流の定
電圧源であつて、例えば80Hz、電圧E0＝8Vの電
源を用いる。試料の穀物、例えば小麦を圧砕して
収容する対電極Ｅa，Ｅbはそれぞれ発振器１と分
流回路２の演算増幅器IC1の反転入力に接続され
ている。演算増幅器IC1の非反転入力は接地され
ている。増幅器IC1の出力は半導体のアナログス
イツチSW1に接続されている。アナログスイツチ
SW1〜SW4は可動接点a1固定接点ｂi，ｃi（ｉ＝
１〜４）を有し、最初a1b1，a2b2……間が接続さ
れており、高水分測定回路をつくる。b1はトラン
ジスタTr1，Tr2からなる電流ブースト回路に接
続されている。そして抵抗R1は演算増幅器IC1の
負帰還回路をつくり、負帰還抵抗R1と負荷抵抗
R2との接続点での出力電圧E1は電流Ｉと抵抗R1
の積でE1＝R1Iとなる。 Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows a measuring circuit of an electrical resistance moisture meter according to the present invention. In the figure, the oscillator 1 is a DC or AC constant voltage source, and uses, for example, a power source of 80 Hz and voltage E 0 =8V. Counter electrodes E a and E b which contain crushed sample grains, for example wheat, are connected to the inverting inputs of the oscillator 1 and the operational amplifier IC 1 of the shunt circuit 2, respectively. The non-inverting input of operational amplifier IC 1 is grounded. The output of amplifier IC 1 is connected to a semiconductor analog switch SW 1 . analog switch
SW 1 to SW 4 are movable contacts a 1 fixed contacts b i , c i (i=
1 to 4), and initially a 1 b 1 , a 2 b 2 . . . are connected to form a high moisture measuring circuit. b1 is connected to a current boost circuit consisting of transistors Tr1 and Tr2 . The resistor R 1 creates a negative feedback circuit for the operational amplifier IC 1 , and the negative feedback resistor R 1 and the load resistor
The output voltage E 1 at the connection point with R 2 is the current I and the resistance R 1
The product of E 1 = R 1 I.
ブロツク３は電流・電圧対数変換回路を表わ
し、該回路には演算増幅器IC2とダイオードD3，
D4を含む。次に、演算増幅器IC2とa2b2間とa3b3
間に接続しているアナログスイツチSW2，SW3に
より対数変換回路を構成している回路３に抵抗
R2を通して電流Ｒ１／Ｒ２Ｉが流れる。すなわち、試料
に流れる電流ＩのＲ１／Ｒ２倍した分流電流が流れる。 Block 3 represents a current/voltage logarithmic conversion circuit, which includes an operational amplifier IC 2 and a diode D 3 .
Contains D4 . Next, between operational amplifier IC 2 and a 2 b 2 and a 3 b 3
A resistor is connected to circuit 3, which constitutes a logarithmic conversion circuit, by analog switches SW 2 and SW 3 connected between them.
A current R 1 /R 2 I flows through R 2 . That is, a shunt current that is R 1 /R 2 times the current I flowing through the sample flows.
そして、a4b4間に接続されたアナログスイツチ
SW4と電圧バツフアー回路IC3を通して、演算・
制御回路５に入る。この回路５で水分信号が低水
分と判断された場合には、アナログスイツチ切換
信号が発生されてアナログスイツチSWi（ｉ＝１
〜４）がａiｃi間に接続される。そして演算増幅
器IC1とダイオードD1，D2によつて構成された対
数増幅器３に直接試料に流れる電流が入り、対数
変換され、そして電圧バツフアー回路IC3を通し
て再び演算制御回路５に入り、直線化回路を通し
て水分表示を行なう表示回路６に入る。And an analog switch connected between a 4 b 4
Through SW 4 and voltage buffer circuit IC 3 , calculation and
It enters the control circuit 5. When this circuit 5 determines that the moisture signal is low moisture, an analog switch switching signal is generated and the analog switch SWi (i=1
~4) are connected between a i c i . Then, the current flowing directly to the sample enters the logarithmic amplifier 3 composed of the operational amplifier IC 1 and the diodes D 1 and D 2 , is converted logarithmically, and then enters the operational control circuit 5 again through the voltage buffer circuit IC 3 , where it is converted into a straight line. It enters a display circuit 6 which displays moisture content through a conversion circuit.
第４図は演算制御回路５の構成を例示する。そ
の回路、動作を第５図にフローチヤートで示す。
演算制御回路は、増幅器IC3からアナログの測定
水分データを受ける整流回路と、レベル設定器
と、水分データと温度信号とを切換えるアナログ
スイツチSW5と、Ａ／Ｄ変換器とマイクロコンピ
ユータをそなえている。試料が電極に入れられて
いないときは、試料セツト信号はＬレベルとな
り、制御信号F2はアナログスイツチSW5をリセ
ツト状態に置き温度検出器からの温度信号をマイ
クロコンピユータに入れている。電極Ea，Ebに
試料が入ると試料セツト信号がＨレベルになり、
アナログスイツチSW5を水分データ入力側に切替
える。Ａ／Ｄ変換された水分データはマイクロコ
ンピユータにより穀類モード入力に応じて水分値
に変換する水分演算と温度補償の演算がされる。
マイクロコンピユータは演算結果に基づいて試料
水分が低水分域か高水分域かを判断し、アナログ
スイツチ制御信号F1を発生し、アナログスイツ
チSW1〜SW4を切替える。 FIG. 4 illustrates the configuration of the arithmetic control circuit 5. The circuit and operation are shown in a flowchart in FIG.
The arithmetic control circuit includes a rectifier circuit that receives analog measured moisture data from the amplifier IC 3 , a level setter, an analog switch SW 5 that switches between moisture data and temperature signals, an A/D converter, and a microcomputer. There is. When no sample is placed in the electrode, the sample set signal is at L level, and the control signal F2 resets the analog switch SW5 to input the temperature signal from the temperature detector into the microcomputer. When the sample enters the electrodes Ea and Eb, the sample set signal becomes H level,
Switch analog switch SW 5 to the moisture data input side. The A/D converted moisture data is subjected to moisture calculation and temperature compensation calculation to convert it into a moisture value according to the grain mode input by a microcomputer.
The microcomputer determines whether the sample moisture is in a low moisture range or a high moisture range based on the calculation result, generates an analog switch control signal F1 , and switches the analog switches SW1 to SW4 .
第６図は、試料を小麦として乾燥させていつた
とき、本装置を用いて縦軸に水分率をパーセント
で、横軸に試料抵抗の対数変換値として表示した
抵抗水分特性図を示す。 FIG. 6 shows a resistance-moisture characteristic diagram in which the moisture content is expressed as a percentage on the vertical axis and the logarithmically converted value of the sample resistance is expressed on the horizontal axis using this apparatus when the sample is dried as wheat.
本発明によれば、従来の水分計では測定できな
かつた、試料抵抗が数100Ωから数百ＭΩに至る
幅の広いダイナミツクレンジで試料水分が自動的
に測定できる。本発明はとくに測定結果をデイジ
タル表示する場合に好適である。 According to the present invention, sample moisture can be automatically measured over a wide dynamic range of sample resistance ranging from several 100 Ω to several 100 MΩ, which could not be measured with conventional moisture meters. The present invention is particularly suitable for digitally displaying measurement results.
第１図と第２図は電気抵抗式水分測定回路の従
来例を示す模式回路図、第３図は本発明の一実施
例を示す回路図、第４図は第３図の演算制御回路
を例示した回路図、第５図は第４図の回路動作を
示すフローチヤート、第６図は試料の抵抗水分特
性図である。
ＲXは試料、D1，D2は対数変換素子、IC1，IC2
はFET入力演算増幅器、IC3は演算増幅器、
Tr1，Tr2はトランジスタ、SW1，SW2，SW3，
SW4はアナログスイツチ、５は演算制御回路。
1 and 2 are schematic circuit diagrams showing a conventional example of an electric resistance moisture measuring circuit, FIG. 3 is a circuit diagram showing an embodiment of the present invention, and FIG. The illustrated circuit diagram, FIG. 5 is a flowchart showing the circuit operation of FIG. 4, and FIG. 6 is a resistance moisture characteristic diagram of the sample. R X is the sample, D 1 and D 2 are logarithmic conversion elements, IC 1 and IC 2
is a FET input operational amplifier, IC 3 is an operational amplifier,
Tr 1 and Tr 2 are transistors, SW 1 , SW 2 , SW 3 ,
SW 4 is an analog switch, and 5 is an arithmetic control circuit.
Claims (1)
電圧変化に変換する手段を用いて、被測定物の電
気抵抗値に対応する含有水分率を該変換電圧の信
号として求め、水分率の指数関数的特性を対数圧
縮して水分率を表示するようにした電気抵抗式水
分測定装置において、高水分域において被測定物
測定電極と電流・対数・電圧変換手段間に電流分
流回路を接断可能に接続するスイツチ手段と、そ
の時の電流・対数・電圧変換手段の出力が低水分
域の水分信号であるとき前記スイツチ手段の切替
動作信号を発生して前記スイツチ手段により前記
測定電極を前記電流・対数・電圧変換手段に直接
接続させる制御手段とをそなえ、広帯域水分測定
を自動的に行えるようにしたことを特徴とする電
気抵抗式水分測定装置。 ２ 特許請求の範囲第１項の装置において、前記
スイツチ手段はアナログスイツチでなることを特
徴とする前記水分測定装置。 ３ 特許請求の範囲第１項又は第２項の装置にお
いて、前記測定電極に印加される定電圧は直流又
は交流電源によつて供給されることを特徴とする
前記水分測定装置。[Claims] 1. Using means for converting changes in current flowing through the object to be measured into changes in voltage when a constant voltage is applied, the moisture content corresponding to the electrical resistance value of the object to be measured is determined as a signal of the converted voltage. In an electrical resistance moisture measuring device that logarithmically compresses the exponential characteristic of moisture content to display the moisture content, current shunting occurs between the object measurement electrode and the current/logarithm/voltage conversion means in a high moisture range. A switch means connects the circuit in a disconnectable manner, and when the output of the current/logarithm/voltage conversion means at that time is a moisture signal in a low moisture range, a switching operation signal is generated for the switch means, and the switch means performs the measurement. An electrical resistance moisture measuring device characterized in that it is equipped with a control means for directly connecting an electrode to the current/logarithm/voltage converting means, and is capable of automatically performing broadband moisture measurement. 2. The moisture measuring device according to claim 1, wherein the switch means is an analog switch. 3. The moisture measuring device according to claim 1 or 2, wherein the constant voltage applied to the measuring electrode is supplied by a direct current or alternating current power source.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12584980A JPS5749849A (en) | 1980-09-10 | 1980-09-10 | Automatic hygrometer of electrical resistance type for wide range application |
| US06/298,542 US4408128A (en) | 1979-03-08 | 1981-09-01 | Electric resistance type wide range moisture meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12584980A JPS5749849A (en) | 1980-09-10 | 1980-09-10 | Automatic hygrometer of electrical resistance type for wide range application |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5749849A JPS5749849A (en) | 1982-03-24 |
| JPS6146778B2 true JPS6146778B2 (en) | 1986-10-16 |
Family
ID=14920457
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12584980A Granted JPS5749849A (en) | 1979-03-08 | 1980-09-10 | Automatic hygrometer of electrical resistance type for wide range application |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5749849A (en) |
-
1980
- 1980-09-10 JP JP12584980A patent/JPS5749849A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5749849A (en) | 1982-03-24 |
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