JPH0326322B2 - - Google Patents

Info

Publication number
JPH0326322B2
JPH0326322B2 JP58038640A JP3864083A JPH0326322B2 JP H0326322 B2 JPH0326322 B2 JP H0326322B2 JP 58038640 A JP58038640 A JP 58038640A JP 3864083 A JP3864083 A JP 3864083A JP H0326322 B2 JPH0326322 B2 JP H0326322B2
Authority
JP
Japan
Prior art keywords
current
differential pressure
output
temperature
converter
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 - Lifetime
Application number
JP58038640A
Other languages
Japanese (ja)
Other versions
JPS59163515A (en
Inventor
Yoshiji Fukai
Kyoshi Odohira
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Yokogawa Electric Corp
Original Assignee
Yokogawa Electric Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Yokogawa Electric Corp filed Critical Yokogawa Electric Corp
Priority to JP58038640A priority Critical patent/JPS59163515A/en
Publication of JPS59163515A publication Critical patent/JPS59163515A/en
Publication of JPH0326322B2 publication Critical patent/JPH0326322B2/ja
Granted legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
    • G01D3/028—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure
    • G01D3/032—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure affecting incoming signal, e.g. by averaging; gating undesired signals

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Fluid Pressure (AREA)
  • Indication And Recording Devices For Special Purposes And Tariff Metering Devices (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)

Description

【発明の詳細な説明】 本発明は差動容量方式の差圧センサを使用する
差圧／電流変換器と該変換器の出力を増幅・変換
する電気回路より成る差圧伝送器に関する。特に
差圧伝送器の周囲温度の影響による性能低下を小
さくするための手段に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a differential pressure transmitter comprising a differential pressure/current converter using a differential capacitance type differential pressure sensor and an electric circuit for amplifying and converting the output of the converter. In particular, the present invention relates to means for reducing performance degradation due to the influence of ambient temperature of a differential pressure transmitter.

差動容量方式の差圧センサは第１図にその断面
図で示すように、両側面が接液ダイヤフラム４と
５で封鎖されている容器内の測定室にこれを７，
８の２部分に分離するダイヤフラム１が測定室周
縁に固定されており、ダイヤフラム１を可動電極
としその両面に対向する測定室の内壁面にそれぞ
れ固定される固定電極２と３が配置され、これら
３つの電極で差動容量を形成する。室内には封入
液６が満たされている。この差圧センサにおいて
は、容器両側面の接液ダイヤフラム４，５に外部
から高圧PHと低圧PLが加わると両圧は封入液６
を介して可動電極の両面に伝達されて可動電極１
にはPHと区PLの差圧が作用し可動電極１は低圧
側固定電極２に近づく方向に偏位する。このとき
の可動電極１の中心偏位ｘと差圧との間に次式が
成立する。 As shown in the cross-sectional view of FIG. 1, the differential pressure sensor of the differential capacitance type is placed in a measuring chamber 7, inside a container whose both sides are sealed with liquid-contact diaphragms 4 and 5.
A diaphragm 1 that is separated into two parts (8) is fixed to the periphery of the measurement chamber.The diaphragm 1 is used as a movable electrode, and fixed electrodes 2 and 3 are arranged on both sides of the diaphragm 1, which are fixed to the inner wall surface of the measurement chamber facing each other. Three electrodes form a differential capacitance. The chamber is filled with a sealed liquid 6. In this differential pressure sensor, when high pressure P H and low pressure P L are applied from the outside to the wetted diaphragms 4 and 5 on both sides of the container, both pressures are reduced to the filled liquid 6.
is transmitted to both sides of the movable electrode via the movable electrode 1.
The differential pressure between P H and P L acts on the movable electrode 1 , and the movable electrode 1 is deviated in the direction approaching the low-pressure side fixed electrode 2 . The following equation holds between the center deviation x of the movable electrode 1 and the differential pressure at this time.

ｘ＝Ｋ（PH−PL） (1) ここでＫは差圧センサの周囲温度が一定の条件
のもとでは定数である。 x=K(P H −P L ) (1) Here, K is a constant under the condition that the ambient temperature of the differential pressure sensor is constant.

この差動容量方式の差圧センサを使つて構成さ
れている差圧／電流変換器PDにおいてはセンサ
の可動電極１と高圧側、低圧側の各固定電極３と
２で形成されるコンデンサCHとCLによつて第２
図に示す電橋回路が形成されている。（コンデン
サCHとCLを高圧側、低圧側のブランチ容量と名
付ける。）この電橋回路では電橋の励振電圧ｅを
制御することによりコンデンサCH，CLを流れる
各電流iHとiLの和は常に一定値ICに保たれる。ま
た、可動電極１と各固定電極２，３との電極間の
初期のギヤツプdpとすれば差圧（PH−PL）と（iL
−iH）との間に下式が成立する。（なおiL，iHをそ
れぞれ低圧側、高圧側のブランチ電流と名付け
る。） iL−iH＝ｘ／dpIC＝KIC／dp（PH−PL） (2) 上式は、Ｋが一定である場合は（iL−iH）が
（PH−PL）に比例することを示す。なお、実際の
差圧／電流変換器PDでは（iL−iH）および（iL＋
iH）はそれぞれ対応する直流信号IM1およびIM2に
変換される。直流信号IM1は入力差圧を代表する
出力電流として変換器PDに縦続する電気回路に
与えられ該回路で増幅され例えば４〜20mAの正
規化電流出力Ipに変換して受信器に送出される。
正規化電流Ipは差圧の計測に利用される。また、
直流信号IM2は変換器PD内で電橋回路に供給され
るICすなわち（iL＋iH）を一定に保つために利用
される。 In the differential pressure/current converter PD configured using this differential capacitance type differential pressure sensor, a capacitor C and 2nd by C.L.
The electric bridge circuit shown in the figure is formed. (Capacitors C H and CL are named branch capacitances on the high voltage side and low voltage side.) In this bridge circuit, by controlling the excitation voltage e of the bridge, the currents i H and i flowing through the capacitors C H and CL are The sum of L is always kept at a constant value I C. Furthermore, if the initial gap between the movable electrode 1 and each of the fixed electrodes 2 and 3 is d p , then the differential pressure (P H − P L ) and (i L
−i H ), the following formula holds true. (Note that i L and i H are named the branch currents on the low voltage side and high voltage side, respectively.) i L −i H = x/d p I C = K I C /d p (P H − P L ) (2) Top The equation shows that (i L −i H ) is proportional to (P H −P L ) when K is constant. In addition, in the actual differential pressure/current converter PD, (i L −i H ) and (i L +
i H ) are converted into corresponding DC signals I M1 and I M2 , respectively. The DC signal I M1 is applied as an output current representing the input differential pressure to an electric circuit connected in series to the converter PD, is amplified by the circuit, is converted into a normalized current output I p of, for example, 4 to 20 mA, and is sent to the receiver. Ru.
The normalized current I p is used to measure differential pressure. Also,
The DC signal I M2 is used within the converter PD to keep I C supplied to the bridge circuit, that is, (i L +i H ) constant.

上記(2)式は変換器の周囲温度が一定の条件のも
とで成立する変換特性式であるが、周囲温度が変
化すれば多少ながらその影響により出力電流IM1
は入力差圧に比例しなくなる。従来からこの種変
換器の変換特性に及ぼす周囲温度の変化の影響を
軽減するためにその構造に種々の工夫が施されて
いるが、まだ完全に温度変化の影響をうけない変
換器は実現されていない。したがつて差圧／電流
変換器の設置されている場所に温度変化があれば
変換器出力電流IM1はその影響をうけこれを増幅
変換せる伝送器出力Ipもまたその影響をこうむり
これがIpを計測する受信器の指示に零点誤差およ
びスパン誤差となつて現れる。その結果差圧測定
の精度が低下する欠点がある。 Equation (2) above is a conversion characteristic equation that holds true under the condition that the ambient temperature of the converter is constant, but if the ambient temperature changes, the output current I M1
is no longer proportional to the input differential pressure. Various improvements have been made to the structure of this type of converter in order to reduce the effects of changes in ambient temperature on its conversion characteristics, but a converter that is completely unaffected by temperature changes has not yet been realized. Not yet. Therefore, if there is a temperature change in the location where the differential pressure/current converter is installed, the converter output current I M1 will be affected by that, and the transmitter output I p , which amplifies and converts it, will also be affected by it, and this will be I. This appears as zero point error and span error in the receiver's instructions for measuring p . As a result, there is a drawback that the accuracy of differential pressure measurement decreases.

本発明の主たる目的は差圧伝送器に含まれてい
る差圧変換器の出力に及ぼす周囲温度の影響を低
減する手段を具備する差圧変換器を含む差圧伝送
器を実現するにある。 The main object of the present invention is to realize a differential pressure transmitter including a differential pressure transducer with means for reducing the effect of ambient temperature on the output of the differential pressure transducer included in the differential pressure transmitter.

なお、差圧伝送システムの受信側の受信器の計
測値に生ずる零点誤差およびスパン誤差は主とし
て伝送器側の変換器において周囲温度の変化の影
響によつて生ずる変換器出力の変化に起因する。
したがつて以下の記述において、前者すなわち受
信側受信器の計測値に生ずる零点誤差およびスパ
ン誤差の原因である後者すなわち伝送側変換器出
力の変動をそれぞれ零点誤差およびスパン誤差と
呼ぶ。 Note that the zero point error and span error that occur in the measured values of the receiver on the receiving side of the differential pressure transmission system are mainly caused by changes in the converter output caused by changes in ambient temperature in the converter on the transmitter side.
Therefore, in the following description, the former, that is, the zero point error and span error that occur in the measured values of the receiving receiver, and the latter, that is, the fluctuations in the output of the transmitting side converter, are referred to as the zero point error and the span error, respectively.

本発明の他の目的は差圧変換器出力の零点誤差
およびスパン誤差を補償する零点誤差補償電流お
よびスパン誤差補償電流を発生する温度誤差補償
回路を構成要素に持つ差圧変換器を具備する差圧
伝送器を提供するにある。 Another object of the present invention is to provide a differential pressure converter having a temperature error compensation circuit as a component, which generates a zero point error compensation current and a span error compensation current for compensating the zero point error and span error of the output of the differential pressure converter. To provide pressure transmitters.

本発明の他の目的は差圧変換器の零点誤差の補
償とスパン誤差の補償を相互独立に行うことので
きる機能を持つ差圧変換器を具備する差圧伝送器
を提供するにある。 Another object of the present invention is to provide a differential pressure transmitter equipped with a differential pressure converter capable of independently compensating for zero point error and span error of the differential pressure converter.

本発明の他の目的は周囲温度が特定の基準温度
と異なる状態のときにのみ零点誤差補償電流およ
びスパン誤差補償電流を発生する前記温度誤差補
償回路を具備する差圧変換器をもつ伝送器を提供
するにある。 Another object of the present invention is to provide a transmitter having a differential pressure converter equipped with the temperature error compensation circuit that generates a zero point error compensation current and a span error compensation current only when the ambient temperature is different from a specific reference temperature. It is on offer.

本発明の他の目的は一定の周囲温度変化に対応
する差圧変換器の零点誤差の補償およびスパン誤
差の補償を単一の回路で行うことのできる温度誤
差補償回路を具備する差圧変換器をもつ電送器を
提供するにある。 Another object of the present invention is to provide a differential pressure converter equipped with a temperature error compensation circuit capable of compensating for the zero point error and span error of the differential pressure converter in response to constant ambient temperature changes in a single circuit. To provide electric transmitters with

以下、本発明実施例を参照して本発明を詳細に
説明する。 Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention.

先ず、本発明の構成が従来の差圧伝送器の構成
と相違する点を明かするためにに従来の差圧変換
器を使用する２線式の差圧伝送システムを説明す
る。第３図はその構成図である。図において、差
圧伝送器Ｐ／Ipは２線式伝送器であり、差圧／電
流変換器PDは入力差圧を代表する差圧変換出力
IM1と電橋回路に供給される動作電流IC＝（iL＋iH）
に対応する直流信号IM2とを出力する電橋回路部
分PD1と前記直流電流IM2と基準電流IRとを比較し
両電流が等しくなるように電橋回路の動作電流IC
を制御する動作電流制御回路部分PD2とより成
る。以下、PD1から出力する出力電流IM1と出力
電流IM2を区別するためIM1を第１出力電流、IM2を
第２出力電流と呼ぶ。差圧／電流変換器PDに縦
続する電気回路は第１出力電流IM1を電圧E2に変
換するＩ／Ｖ変換器、変換増幅器Ａ、出力トラン
ジスタQ1および帰還抵抗Rf2等を含む。伝送器
Ｐ／Ipは差圧の測定現場に配設され、この伝送器
Ｐ／Ipに含まれる各演算回路の動作電力は受信側
PMの電源EIから伝送線１２を通じて供給され
る。変換器PDの電橋回路部分PD1の第１出力電
流IM1はＩ／Ｖ，Ｖ／Ｉ等一連の信号変換回路に
よつてDC4〜20mAの正規化出力電流Ipに変換さ
れ伝送線１２を介して受信側PMに伝送される。
また、差圧変換器PDの電橋回路部分PD1の第２
出力電流IM2は基準電流IRと比較されその差は制
御増幅器U1に加えられる。制御増幅器U1の出力
は変換器PDに含まれている電橋回路（図示せず）
の動作電流（iL＋iH）が常にIRに対応し一定の電
流ICになるように交流発振器OSCの出力振幅ｅを
制御する。伝送器Ｐ／Ipの電流入出力端１８，１
９の電圧V1は定電流回路Ｊおよびゼナーダイオ
ードDZで定電圧V2に変換される。V2は伝送器
Ｐ／Ipの各演算増幅器を駆動する電源として利用
される。 First, a two-wire differential pressure transmission system using a conventional differential pressure converter will be described in order to clarify the difference between the configuration of the present invention and the configuration of a conventional differential pressure transmitter. FIG. 3 is a diagram showing its configuration. In the figure, the differential pressure transmitter P/I p is a two-wire transmitter, and the differential pressure/current converter PD is a differential pressure conversion output representative of the input differential pressure.
Operating current I C supplied to I M1 and the bridge circuit = (i L + i H )
The electric bridge circuit section PD1 outputs a DC signal I M2 corresponding to the DC current I M2 and the reference current I R , and the operating current I C of the electric bridge circuit is adjusted so that both currents are equal.
It consists of an operating current control circuit section PD 2 that controls the current. Hereinafter, in order to distinguish between the output current I M1 and the output current I M2 output from PD 1 , I M1 will be referred to as a first output current, and I M2 will be referred to as a second output current. The electrical circuit cascaded to the differential pressure/current converter PD includes an I/V converter that converts the first output current I M1 into a voltage E 2 , a conversion amplifier A, an output transistor Q 1 and a feedback resistor Rf 2 . The transmitter P/I p is installed at the site where differential pressure is measured, and the operating power of each arithmetic circuit included in this transmitter P/I p is
It is supplied through the transmission line 12 from the power source E I of the PM. The first output current I M1 of the electric bridge circuit portion PD 1 of the converter PD is converted into a normalized output current I p of 4 to 20 mA DC by a series of signal conversion circuits such as I/V and V/I, and then connected to the transmission line 12. is transmitted to the receiving PM via.
Also, the second part of the electric bridge circuit part PD 1 of the differential pressure converter PD
The output current I M2 is compared to the reference current I R and the difference is applied to the control amplifier U 1 . The output of the control amplifier U 1 is connected to the bridge circuit (not shown) included in the converter PD.
The output amplitude e of the AC oscillator OSC is controlled so that the operating current (i L +i H ) always corresponds to I R and becomes a constant current I C . Current input/output terminals 18, 1 of transmitter P/I p
The voltage V 1 of 9 is converted into a constant voltage V 2 by a constant current circuit J and a Zener diode D Z. V 2 is used as a power source to drive each operational amplifier of the transmitter P/I p .

第４図は第３図で例示せる２線式伝送システム
を採用せる差圧伝送器Ｐ／Ipに本発明を実施せる
回路例の概略の構成を示す。図において第３図は
各部に付した記号と同じ符号を付してある部分は
第３図と同一部分である。以下、各図においてＥ
は電圧源およびその電圧値を、Ｒは抵抗器および
その抵抗値を代表する。図において第３図に示さ
れている差圧伝送器Ｐ／Ipとこれに対応する第４
図の伝送器Ｐ／Ipとの相違する部分は両者の変換
器PDの部分のみである。後者の変換器PDには温
度誤差補償回路TCが設けられており、その出力
電流±IZはPDの出力回路の電流加算点S1におい
てPD1の第１出力電流IM1と適当な極性で加算さ
れ、他方の出力電流±ISはPD1の第２出力電流IM2
の出力回路の加算点S2において（IM2−IR）に適
当な極性で加算される。±IZを零点誤差補償電流、
±ISをスパン誤差補償電流と名付ける。 FIG. 4 shows a schematic configuration of a circuit example in which the present invention can be implemented in a differential pressure transmitter P/I p employing the two-wire transmission system illustrated in FIG. In FIG. 3, the parts with the same symbols as those given to each part are the same parts as in FIG. 3. Below, in each figure, E
represents a voltage source and its voltage value, and R represents a resistor and its resistance value. In the figure, the differential pressure transmitter P/I p shown in Fig. 3 and the corresponding fourth
The only difference from the transmitter P/I p shown in the figure is the converter PD of both. The latter converter PD is equipped with a temperature error compensation circuit TC, whose output current ±I Z has an appropriate polarity with the first output current I M1 of PD 1 at the current addition point S 1 of the PD output circuit. The other output current ±I S is the second output current I M2 of PD 1
At the addition point S2 of the output circuit, it is added to (I M2 - I R ) with an appropriate polarity. ±I Z is the zero point error compensation current,
± IS is named the span error compensation current.

第５図は第４図で例示せる本発明実施例におけ
る差圧変換器PDに含まれる温度誤差補償回路TC
部分のより詳細な構成を示す。この回路TCは温
度差検出回路TBとTBの出力電圧Ｅを零点誤差
補償電流±IZとスパン誤差補償電流±ISとの２電
流に変換する電圧・電流変換回路Ｅ／Ｉとより成
る。 Figure 5 shows a temperature error compensation circuit TC included in the differential pressure converter PD in the embodiment of the present invention illustrated in Figure 4.
A more detailed configuration of the parts is shown. This circuit TC consists of a temperature difference detection circuit TB and a voltage/current conversion circuit E/I that converts the output voltage E of TB into two currents: a zero point error compensation current ±I Z and a span error compensation current ± IS .

温度差検出回路TBは一種の温度差検出ブリツ
ジで、使用温度内の特定の基準温度Tpと周囲温
度ｔとの差（ｔ−tO）に比例する出力電圧Ｅを生
ずる。ここで例示されているTBは周囲温度のセ
ンサとしてトランジスタQ2およびダイオードD1，
D2を利用し、ブリツジの電源として差圧伝送器
に含まれる演算増幅器の動作電源V2を利用して
構成されている。一般にシリコントランジスタの
ベース・エミツタ間の順方向電圧降下VBEはトラ
ンジスタを使用する−50〜200℃の常温範囲で約
−2mV／℃の温度係数をもつてる。シリコンダ
イオードの順方向電圧降下も同様の温度依存性を
もつ。 The temperature difference detection circuit TB is a kind of temperature difference detection bridge, which produces an output voltage E that is proportional to the difference (t-t O ) between a specific reference temperature T p within the operating temperature and the ambient temperature t. The TB illustrated here has a transistor Q 2 and a diode D 1 as a sensor for ambient temperature,
D 2 and the operation power supply V 2 of the operational amplifier included in the differential pressure transmitter is used as the bridge power supply. Generally, the forward voltage drop V BE between the base and emitter of a silicon transistor has a temperature coefficient of about -2 mV/°C in the normal temperature range of -50 to 200°C where the transistor is used. The forward voltage drop of a silicon diode also has a similar temperature dependence.

TBはこの温度特性を利用したブリツジ回路で
ある。図に示す如く−間の枝路はQ2のベー
ス・エミツタ間回路、ダイオードD1，D2、抵抗
R1および可変抵抗R2の直列回路で構成され、
−間の枝路には定抵抗R3が接続される。−
間の電位点Ｇは伝送器に含まれる演算増幅器の
演算基準点Ｇと同電位の点であつて基準電圧V2
の中間の特定電位に保たれる。図で点線で示され
ている抵抗RA，RBはここには実際に使用されて
いない。伝送器内で演算基準点Ｇを基準電圧V2
の中間の所望の電位に定めている分圧要素を等価
的に表わしたものである。TBは、伝送器が使用
される周囲温度の上限温度t+を例えば80℃、下限
温度t-を例えば−20℃と定め、その中間の温度例
えば30℃を基準温度tpと定め、可変抵抗R2を調整
し基準温度tpで検電端子−間に発生する電圧
Ｅを零に平衡し以後R2の調整位置をそこに固定
して使用される。この状態に調整されている回路
では周囲温度ｔと基準温度tpとの差（ｔ−tp）に
近似的比例する電圧Ｅが検電端子−間に発生
する。この場合、感温素子Q2，D1，D2に流れる
順方向電流により素子の端子間に発生する電圧の
温度係数は負であるからｔがtpより高い領域では
に対するの電圧Ｅは正、ｔがtpより低い領域
では負である。上限温度ｔ＋に対応するＥは正の
最大値となりｔが低下するにしたがつて低減しｔ
＝tpで零となりなおｔが低下すればＥは負に変じ
下限温度ｔ−で負の最小値となる。 TB is a bridge circuit that utilizes this temperature characteristic. As shown in the figure, the branch between - is the base-emitter circuit of Q2 , diodes D1 , D2 , and resistor.
Consists of a series circuit of R 1 and variable resistor R 2 ,
A constant resistance R 3 is connected to the branch line between -. −
The potential point G in between is a point at the same potential as the operational reference point G of the operational amplifier included in the transmitter, and the reference voltage V 2
is maintained at a specific potential between . The resistors R A and R B indicated by dotted lines in the figure are not actually used here. The calculation reference point G is set to the reference voltage V 2 in the transmitter.
This is an equivalent representation of a voltage dividing element that is set at a desired potential between . For TB, the upper limit temperature t + of the ambient temperature at which the transmitter is used is set to, for example, 80°C, the lower limit temperature t - is set to, for example, −20°C, and the intermediate temperature, for example, 30°C, is set as the reference temperature t p , and the variable resistor is R2 is adjusted to balance the voltage E generated between the voltage detection terminal and the voltage detection terminal to zero at a reference temperature tp , and thereafter the adjustment position of R2 is fixed at that position for use. In a circuit adjusted to this state, a voltage E approximately proportional to the difference (t- tp ) between the ambient temperature t and the reference temperature tp is generated between the voltage detection terminals. In this case, the temperature coefficient of the voltage generated between the terminals of the temperature sensing elements Q 2 , D 1 , and D 2 due to the forward current flowing through them is negative, so in the region where t is higher than t p , the voltage E is positive. , is negative in the region where t is lower than t p . E corresponding to the upper limit temperature t+ has a positive maximum value and decreases as t decreases.
= t becomes zero at p , and if t decreases, E changes to negative and reaches a negative minimum value at the lower limit temperature t-.

第５図に示す温度差検出回路TBにおいては温
度センサとしてトランジスタQ2およびダイオー
ドD1，D2を組合せて利用しているが、温度セン
サはこれらの素子の組合せに限定するものではな
い。例えばダイオードのみを使用し、その数も任
意であつてよい。また、サーミスタ、あるいは抵
抗の温度係数が比較的大きい金属線を使用しても
よい。ここで温度センサとして使用される素子を
総称して感温素子を名付ける。 Although the temperature difference detection circuit TB shown in FIG. 5 uses a combination of transistor Q 2 and diodes D 1 and D 2 as a temperature sensor, the temperature sensor is not limited to the combination of these elements. For example, only diodes may be used, and any number of diodes may be used. Alternatively, a thermistor or a metal wire with a relatively large temperature coefficient of resistance may be used. Here, elements used as temperature sensors are collectively called temperature sensing elements.

変換回路Ｅ／Ｉは演算増幅器U3で構成されて
いる電圧ホロアU3（以下電圧ホロアをU3で代表し
U3と称する）と、同じ値の２つの抵抗Ｒと演算
増幅器U4で構成されている反転回路U4（以下この
回路をU4で代表しU4と呼ぶ）と、U3の出力端
とU4の出力端とを橋絡する２つの滑り線抵抗
RV1とRV2と、各滑り線抵抗RV1とRV2の摺動子
d1，d2にそれぞれ接続する出力抵抗RZ，RSとで
構成される。 The conversion circuit E/I is a voltage follower U 3 (hereinafter the voltage follower is represented by U 3 ), which is composed of an operational amplifier U 3 .
an inverting circuit U 4 (hereinafter this circuit is represented by U 4 and referred to as U 4 ), which is composed of two resistors R of the same value and an operational amplifier U 4 , and an output terminal of U 3 . and two sliding wire resistors bridging the output end of U 4
RV 1 and RV 2 and slider of each sliding line resistance RV 1 and RV 2
It consists of output resistors R Z and R S connected to d 1 and d 2 , respectively.

電圧ホロアU3はTBの出力端とU3の出力端
とを電気的に分離し点にTB出力端と同じ電
圧Ｅの電圧源を得るための緩衝増幅器である。周
囲温度ｔがｔ＋とtpの範囲にあればRV1とRV2の
並列回路の１端には＋Ｅが他端には−Ｅが印
加される。また、tp〜ｔ−の範囲にあればに−
Ｅ、に＋Ｅが印加される。RV1の摺動子d1に発
生する可変電圧±EZは出力抵抗RZにより可変電
流±IZに変換され、±IZは零点誤差補償電流とし
て差圧変換器PDの加算点S1に送出される。RV2
の摺動子d2に発生する可変電圧±ESは出力抵抗
RSによりスパン誤差補償電流±ISに変換されPD
の加算点S2に送出される。 The voltage follower U3 is a buffer amplifier for electrically separating the output terminal of TB and the output terminal of U3 , and obtaining a voltage source of the same voltage E as that of the TB output terminal at a point. If the ambient temperature t is in the range between t+ and tp , +E is applied to one end of the parallel circuit of RV 1 and RV 2 , and -E is applied to the other end. Also, if it is in the range of t p to t-, then -
+E is applied to E. The variable voltage ±E Z generated on the slider d 1 of RV 1 is converted into a variable current ±I Z by the output resistor R Z , and ±I Z is used as the zero point error compensation current at the summing point S 1 of the differential pressure converter PD. sent to. RV 2
The variable voltage ±E S generated on the slider d2 is the output resistance
R S converts the span error compensation current ±I S to PD
is sent to the summing point S2 .

第６図Ａは変換器Ｅ／Ｉの一方の滑り線抵抗例
えばRV1の構成説明図であり、第６図Ｂ滑り線抵
抗RV1上を摺動する摺動子d1の接触位置とd1にピ
ツクアツプされるEZとの対応関係を示す特性線
図である。図において(1)は周囲温度が上限温度ｔ
＋の場合、(2)は下限温度ｔ−の場合の特性線であ
る。図から明かなようにｔ＋の場合端に印加さ
れる電圧を＋Ｅとすれば摺動子d1が滑り線上を１
端からに向つて移動するにしたがつて摺動子
d1の電圧EZは＋Ｅから連続的に低下し中央点で
零となりを過ぎれば負に転じ他端に達すれば
−Ｅとなる。したがつて特定値の抵抗RZを通り
出力回路に流れ出る零点誤差補償電流IZもEZの変
化に対応し連続的に低下する。また、周囲温度が
ｔ−の場合EZの変化はｔ＋の場合と反対である。
周囲温度ｔが任意の温度ｔの場合はEZはその温
度ｔに対応した変化をたどる。図では任意の温度
ｔに対する特性線を(3)に例示する。 FIG . 6A is an explanatory diagram of the configuration of one sliding line resistance, for example RV 1 , of the converter E/I, and FIG . 1 is a characteristic diagram showing the correspondence relationship with E Z picked up in No. 1. FIG. In the figure (1), the ambient temperature is the upper limit temperature t
In the case of +, (2) is the characteristic line in the case of the lower limit temperature t-. As is clear from the figure, in the case of t+, if the voltage applied to the end is +E, the slider d 1 will move on the sliding line by 1
As the slider moves from the end to
The voltage E Z of d 1 continuously decreases from +E, reaches zero at the center point, becomes negative after passing through it, and becomes -E when it reaches the other end. Therefore, the zero point error compensation current I Z flowing through the resistor R Z having a specific value and flowing into the output circuit also decreases continuously in response to the change in E Z. Further, when the ambient temperature is t-, the change in E Z is opposite to that when the ambient temperature is t+.
When the ambient temperature t is an arbitrary temperature t, E Z follows a change corresponding to the temperature t. In the figure, a characteristic line for an arbitrary temperature t is illustrated in (3).

図７図はTCに含まれるＥ／Ｉ回路における２
つの補償電流±IZおよび±ISを出力する回路部分
の構成を示す等価回路である。RV1は零点誤差補
償電流±IZを得るための滑り線抵抗、RV2はスパ
ン誤差補償電流±ISを得るための滑り線抵抗であ
る。単一の補償電流を出力するTC回路を２つの
補償電流を出力する回路に変更するには＋Ｅ，−
Ｅを出力する出力端，に橋絡する滑り線抵抗
の数を１個から２個に変更するだけでよい。 Figure 7 shows 2 in the E/I circuit included in the TC.
This is an equivalent circuit showing the configuration of a circuit portion that outputs two compensation currents ±I Z and ±I S. RV 1 is the sliding line resistance for obtaining the zero point error compensation current ±I Z , and RV 2 is the sliding line resistance for obtaining the span error compensation current ± IS . To change a TC circuit that outputs a single compensation current to a circuit that outputs two compensation currents, use +E, -
It is only necessary to change the number of sliding wire resistances bridging to the output end that outputs E from one to two.

次に温度誤差補償回路TCの出力電流±IZ、お
よび±ISによつて零点誤差およびスパン誤差の補
償を行う回路の作用を説明する。 Next, the operation of the circuit that compensates for the zero point error and span error using the output currents ±I Z and ±I S of the temperature error compensation circuit TC will be explained.

現在実用されている多くの差圧変換器の性能に
ついて次の事項が実験的に知られている。いま入
出力間の変換係数ΔIM1／ΔPi（但しΔPiは入力信号
Piの微小変化、ΔIM1はΔPiに対する出力電流IM1の
微小変化）が等しいと保証されている同種の変換
器について、 (i) 差圧変換器PDの変換係数は変換器の測定範
囲の入力Piについて一定とみなすことができ
る。したがつて入力Piのフルスケール値Pi
（ｆ・ｓ）に対する出力IM1のフルスケール値
IM1（ｆ・ｓ）の比も一定とみなすことができ
る。 The following points are experimentally known regarding the performance of many differential pressure converters currently in use. Now, the conversion coefficient between input and output ΔI M1 /ΔP i (where ΔP i is the input signal
For similar converters that are guaranteed to have the same small change in P i (ΔI M1 is the small change in output current I M1 with respect to ΔP i) , (i) the conversion coefficient of the differential pressure converter PD is determined by the measurement range of the converter. can be regarded as constant for the input P i . Therefore, the full scale value P i of input P i
Full scale value of output I M1 for (f・s)
The ratio of I M1 (f·s) can also be considered constant.

(ii) 変換器PDの使用温度範囲ｔ＋〜ｔ−の中の
任意の温度ｔにおける零点誤差およびスパン誤
差は温度ｔと特定の基準温度tpとの差（ｔ−tp）
に比例する。(ii) The zero point error and span error at any temperature t within the operating temperature range t+ to t- of the converter PD are the difference between temperature t and a specific reference temperature t p (t-t p )
is proportional to.

(iii) 同種多数の差圧変換器PDにおいて、各変換
器の零点誤差およびスパン誤差は最小スパンの
数％以内であるが個々の変換器における誤差の
大きさおよび極性ともにまちまちである。(iii) In a large number of differential pressure converters PD of the same type, the zero point error and span error of each converter are within several percent of the minimum span, but the magnitude and polarity of the error in each converter vary.

本発明においてはこのような同種の変換器の温
度による零点誤差およびスパン誤差を先に説明し
た同一構成の温度誤差補償回路TCの零点誤差補
償電流±IZおよびスパン誤差補償電流ISで補償し
ようとするものである。また、本発明の補償回路
TCの誤差補償電流IZ，ISを変換器PDの出力電流
IM1，およびPDの出力電流IM2に付加しても基準温
度tpに対する入出力特性に影響を及ぼさないTC
を実現せんとするものである。 In the present invention, the zero point error and span error due to the temperature of such converters of the same type are compensated by the zero point error compensation current ±I Z and the span error compensation current I S of the temperature error compensation circuit TC having the same configuration as described above. That is. Moreover, the compensation circuit of the present invention
The error compensation currents I Z and I S of the TC are converted into the output current of the converter PD.
I M1 and a TC that does not affect the input/output characteristics with respect to the reference temperature t p even when added to the PD output current I M2
This is what we aim to achieve.

第８図は変換器PDにおける零点誤差補償に関
連する回路部分の構成説明図である。図において
PDの第１出力電流IM1を出力する電源を等価的に
Eiにより、またその出力抵抗を等価抵抗Riによつ
て示す。また、温度誤差補償回路TCにおける零
点誤差補償電流IZの出力回路部分をTC（Ｚ）で表
わしこれを滑り線抵抗RV1の摺動子d1に生ずる可
変電圧±EZと出力抵抗RZで示す。補償電流±IZは
PDの出力端１１とＩ／Ｖ変換器の入力端１３と
の間の加算点S1に導入される。±Ｖの電圧が印加
されている可変抵抗RVOはIM1の零調整用の抵抗
である。 FIG. 8 is an explanatory diagram of the configuration of a circuit portion related to zero point error compensation in the converter PD. In the figure
Equivalently, the power supply that outputs the first output current I M1 of the PD is
Denote by E i and its output resistance by the equivalent resistance R i . In addition, the output circuit portion of the zero point error compensation current I Z in the temperature error compensation circuit TC is expressed as TC (Z), and this is expressed as the variable voltage ±E Z generated on the slider d 1 of the sliding wire resistance RV 1 and the output resistance R Z Indicated by Compensation current ±I Z is
It is introduced at the summing point S 1 between the output terminal 11 of the PD and the input terminal 13 of the I/V converter. The variable resistor R V0 to which a voltage of ±V is applied is a zero adjustment resistor for I M1 .

第９図は差圧変換器PDにおけるスパン誤差補
償に関連する部分の回路構成を示す。差圧変換器
PDの電橋回路部分PD1の第２出力電流IM2とこれ
と比較する基準電流iRとの加算点S2にTC（Ｓ）か
らスパン誤差補償電流±ISが導入される。±ESは
TC回路の第２の滑り線抵抗RV2の摺動子d2に生
ずる可変電圧を代表する。 FIG. 9 shows the circuit configuration of a portion related to span error compensation in the differential pressure converter PD. differential pressure converter
A span error compensation current ±I S is introduced from TC(S) to the addition point S 2 of the second output current I M2 of the bridge circuit portion PD 1 of the PD and the reference current i R to be compared with it. ± ES is
It represents the variable voltage present on the slider d 2 of the second sliding wire resistance RV 2 of the TC circuit.

第６図、第８図を参照し零点誤差補償作用を説
明する。 The zero point error compensation action will be explained with reference to FIGS. 6 and 8.

まず、基準温度tpにおいて零点調整用の可変抵
抗を調整して入力差圧Piが零に対する出力電流
IM1を零にする。上限温度ｔ＋における零点誤差
は前述の如く個々の変換器において異なつている
がその中でｔ＋における誤差の最大値IM1（MAX）
は既知である。かかる場合に温度誤差補償回路
TCにおけるＥ／Ｉ回路の滑り線抵抗RV1の摺動
子d1を滑り線の端または端上に置きd1を通つ
て流出する補償電流IZの絶対値がｔ＋における
IM1（MAX）の絶対値より大きい値になるように
IZ出力回路の抵抗RZの抵抗値を定める。個々の変
換器において、使用温度の変化範囲ｔ＋〜ｔ−の
間の任意の温度ｔにおける零点誤差の大きさはｔ
＋におけるIM1（MAX）の絶対値以下であるから、
出力抵抗RZが上述のように設定してあれば、周
囲温度ｔが未知であつても摺動子d1を滑り線上の
−間を摺動することにより零点誤差すなわち
出力電流IM1が零になる点にd1を位置決めするこ
とができる。なお摺動子d1の位置決めは基準温度
tpにおいて較正されている入力Piの零に対応する
伝送器の正規化出力Ipの計測値を参照して行われ
る。 First, adjust the variable resistor for zero point adjustment at the reference temperature t p to adjust the output current when the input differential pressure P i is zero.
I Set M1 to zero. The zero point error at the upper limit temperature t+ differs for each converter as mentioned above, but the maximum error value at t+ is I M1 (MAX)
is known. In such cases, temperature error compensation circuit
The slider d 1 of the slip wire resistance RV 1 of the E/I circuit at TC is placed at or on the end of the slip wire and the absolute value of the compensation current I Z flowing out through d 1 at t+
so that the value is greater than the absolute value of I M1 (MAX)
Determine the resistance value of the resistor R Z of the I Z output circuit. For each converter, the magnitude of the zero point error at any temperature t within the operating temperature range t+ to t- is t
Since it is less than the absolute value of I M1 (MAX) at +,
If the output resistance R Z is set as described above, even if the ambient temperature t is unknown, by sliding the slider d 1 between - on the sliding line, the zero point error, that is, the output current I M1 will be zero. We can position d 1 at the point where d 1 becomes . Note that the positioning of slider d1 is based on the reference temperature.
This is done with reference to the measured value of the normalized output I p of the transmitter corresponding to the zero of the input P i being calibrated at t p .

次に、第７図、第９図および第１０図を参照し
スパン誤差補償作用を説明する。 Next, the span error compensation effect will be explained with reference to FIGS. 7, 9, and 10.

第１０図は差圧変換器PDの入力差圧Piと出力
電流IM1との間の入出力特性を示す線図である。
図において、特性線(1)は基準温度tpにおける特性
線を示す。なおここに示されている線図は変換器
の差圧センサによる電橋回路（第２図参照）の動
作電流（iL＋iH）が一定の基準電流IRに対応する
一定値に保たれている条件のもとでの特性線であ
る。特性線(2)は上記の条件のもとにおける例えば
周囲温度がそ上限温度ｔ＋のときの入出力特性線
を例示する。なお線２はｔ＋のときの零点誤差は
補償済の特性線である。いま第９図に例示せる変
換器において入力Piの任意の値ｐに対する上限温
度ｔ＋における出力電流IM1をI(t+)p，基準温度tpに
おけるIM1をI(tp)pで表せば上限温度ｔ＋における
入力差圧ｐに対するスパン誤差εS(t+)は下式で定
義される。 FIG. 10 is a diagram showing the input/output characteristics between the input differential pressure P i and the output current I M1 of the differential pressure converter PD.
In the figure, characteristic line (1) shows the characteristic line at the reference temperature tp . The diagram shown here indicates that the operating current (i L + i H ) of the electric bridge circuit (see Figure 2) by the differential pressure sensor of the converter is kept at a constant value corresponding to a constant reference current I R. This is the characteristic line under the following conditions. Characteristic line (2) exemplifies the input/output characteristic line under the above conditions, for example, when the ambient temperature is at its upper limit temperature t+. Note that line 2 is a characteristic line for which the zero point error at t+ has been compensated. Now, in the converter illustrated in Fig. 9, if the output current I M1 at the upper limit temperature t+ for any value p of the input P i is expressed as I (t+)p , and I M1 at the reference temperature t p is expressed as I (tp)p , then The span error ε S(t+) with respect to the input differential pressure p at the upper limit temperature t+ is defined by the following formula.

εS(t+)＝I(t+)p／ｐ−I（to）ｐ／ｐ (4) 説明の便宜上入力Piの最大値ｐ（MAX）に対す
るｔ＋およびtpにおける出力電流ＩをI(t+)(fs)およ
びI(tp)(fs)で表せばεS(t+)は下式で表わすことができ
る。 ε S(t+) = I (t+)p /p−I(to)p/p (4) For convenience of explanation, the output current I at t+ and t p with respect to the maximum value p (MAX) of input P i is expressed as I (t+ )(fs) and I (tp)(fs) , ε S(t+) can be expressed by the following formula.

εS(t+)＝I(t+)(fs)−I（to）（fs）／Ｐ（MAX） (5) しかるに上限温度ｔ＋における出力電流は差圧
センサに含まれている電橋回路（第２図参照）の
動作電流IM2＝（iL＋iH）に比例ししたがつてPDの
加算点S2でIM2と比較される基準電流IRに比例す
る。したがつて(5)式εS(t+)は下式となる。 ε S(t+) = I (t+)(fs) −I(to)(fs)/P(MAX) (5) However, the output current at the upper limit temperature t+ is (see Figure 2) is proportional to the operating current I M2 = (i L + i H ) and is therefore proportional to the reference current I R which is compared with I M2 at the addition point S2 of the PD. Therefore, equation (5) ε S(t+) becomes the following equation.

εs(t+)＝K(t)IR・Ｐ（MAX）−I(tp)(fs)Ｐ（MAX）(6
) 但しK(t)は周囲温温度ｔの関数であり上限温度
ｔ＋において一定である。 ε s(t+) =K (t) I R・P(MAX)−I (tp)(fs) P(MAX)(6
) However, K (t) is a function of the ambient temperature t and is constant at the upper limit temperature t+.

ここで誤差を補償するために加算点S2において
スパン誤差補償電流ISをIRに加算するが第１０図
に例示するごとくI(t+)(fs)＞I(tp)(fs)の場合は誤差
εS(t+)を零に減ずるためには(6)式の右辺を零と置
いた下式を満足するIS加算点S2に供給しなければ
ならない。 Here, in order to compensate for the error, the span error compensation current I S is added to I R at the addition point S 2 , but as shown in Fig. 10, when I (t+)(fs) > I (tp)(fs) In order to reduce the error ε S(t+) to zero, it must be supplied to the I S addition point S 2 that satisfies the following equation, where the right side of equation (6) is set to zero.

K(t)（IR−IS）Ｐ（max）−I(tp)(fs)＝０ (7) 一方、上限温度ｔ＋においてスパン誤差の最大
値すなわちI(t+)(fs)の最大値I(t+)MAXは既知であれ
ば、零点誤差補償の場合と同様にTC回路におけ
るＥ／Ｉ回路のスパン誤差補償電流±ISの出力回
路の電源用滑り線抵抗RV2の摺動子d2を滑り線の
端上に置きd2を通つて流出するスパン誤差補償
電流±ISの絶対値がI(t+)MAXの絶対値より大きな値
になるよう±ISの出力回路の抵抗RSの値を定め
る。かくすれば、個々の変換器におけるｔ＋の出
力信号I(t)(fs)はI(t+)MAX以下であるから摺動子d2を滑
り線上の−間を摺動することにより(7)式を満
足する点にd2を位置決めすることができる。すな
わち特性線(2)を基準温度tpにおける特性線(1)に合
致させることができる。 K (t) (I R − I S ) P (max) − I (tp)(fs) = 0 (7) On the other hand, at the upper limit temperature t+, the maximum value of the span error, that is, the maximum value of I (t+)(fs) If I (t+)MAX is known, as in the case of zero point error compensation, the span error compensation current of the E/I circuit in the TC circuit ±I S The slider d of the power supply sliding wire resistance RV 2 of the output circuit 2 on the end of the sliding wire and the resistance R of the output circuit of ± I S so that the absolute value of the span error compensation current ±I S flowing out through 2 is greater than the absolute value of I (t+)MAX. Determine the value of S. In this way, since the output signal I (t)(fs) of t+ in each converter is less than I (t+)MAX , by sliding the slider d 2 between - on the sliding line, (7) d 2 can be positioned at a point that satisfies Eq. In other words, the characteristic line (2) can be matched with the characteristic line (1) at the reference temperature tp .

また、特性線(4)に示すごとくI(t+)(fs)2がI(tp)(fs)
以
下の場合は基準電流IRに加えられるISの極性が正
の範囲で特性線(4)を特性線(1)に合致させることが
できる。また、使用温度の変化範囲ｔ＋〜ｔ−の
間の任意の温度ｔにおけるスパン誤差はｔが未知
であつても摺動子d2をRV2の−間を摺動する
だけで入力の任意の値ｐに対する出力電流I(t)を
基準温度におけるI(tp)と一致させることができる。 Also, as shown in characteristic line (4), I (t+)(fs)2 is I (tp)(fs)
 In the following cases, the characteristic line (4) can be made to match the characteristic line (1) as long as the polarity of I S added to the reference current I R is within the positive range. Furthermore, even if t is unknown, the span error at any temperature t within the operating temperature range t+ to t- can be determined by simply sliding the slider d 2 between RV 2 and -. The output current I (t) for the value p can be matched with I (tp) at the reference temperature.

本発明によれば(i)零点誤差およびスパン誤差の
補償を相互干渉なしに行うことができる。(ii)任意
の温度ｔにおいて零点誤差補償回路およびスパン
誤差補償回路のみの操作で基準温度tpにおける較
正時の入出力特性と一致する特性の差圧変換器が
実現できる。(iii)本発明による零点誤差補償電流±
IZおよびスパン誤差補償電流±ISは基準温度tpに
おいて零になるのでこれを変換器に付加しても基
準温度における入出力特性に変化を生ずることが
ない。(iv)零点誤差の補償は測定レンジ変更を行な
うＩ／Ｖ変換器の前段で行なれるように伝送器が
構成されているので測定レンジの変更により零点
誤差補償電流に過不足を生じない。 According to the present invention, (i) zero point error and span error can be compensated for without mutual interference. (ii) At any temperature t, by operating only the zero point error compensation circuit and the span error compensation circuit, a differential pressure converter with characteristics matching the input/output characteristics during calibration at the reference temperature t p can be realized. (iii) Zero point error compensation current according to the present invention ±
Since I Z and the span error compensation current ±I S become zero at the reference temperature t p , adding them to the converter will not cause any change in the input/output characteristics at the reference temperature. (iv) Since the transmitter is configured so that zero point error compensation can be performed before the I/V converter that changes the measurement range, changing the measurement range will not cause excess or deficiency in the zero point error compensation current.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の差圧変換器の一部である差動
容量方式の差圧センサの断面図を示す。第２図は
第１図の差圧センサを使用して構成されている電
橋回路部分の原理図を示す。第３図は従来公知の
２線式差圧伝送方式の構成図である。第４図は本
発明の実施せる２線式差圧伝送器の概略の構成を
示す。第５図は第４図の本発明実施例における差
圧変換器に含まれる温度誤差補償回路の詳細な構
成を示す。第６図Ａは本発明を実施せる差圧変換
器の温度誤差補償回路の一部である電圧／電流変
換器の一方の滑り線抵抗の構成説明図、第６図Ｂ
は滑り線抵抗上を摺動する摺動子の接触位置と摺
動子上の電圧との対応関係を示す。第７図は温度
誤差補償回路に含まれる電圧／電流変換器の出力
回路部分の構成を示す当価回路である。第８図は
本発明を実施せる差圧変換器部分における零点誤
差補償に関連する回路部分の構成を示す。第９図
は本発明を実施せる差圧変換器部分におけるスパ
ン誤差補償に関連する部分の回路構成を示す。第
１０図は差圧変換器の入出力特性を示す線図であ
る。 第４図において、PD…差圧変換器、PD1…差
圧変換器の電橋回路部分、PD2…差圧変換器の動
作電流制御回路部分、TC…温度誤差補償回路、
Ｉ／Ｖ…電流電圧変換回路、S1…加算点、S2…加
算点、IR…基準電流、RV1…第１滑り線抵抗、d1
…第１摺動子、RV2…第２滑り線抵抗、d2…第２
摺動子、RZ…第１出力抵抗、RS…第２出力抵抗。 FIG. 1 shows a cross-sectional view of a differential capacitance type differential pressure sensor that is part of the differential pressure converter of the present invention. FIG. 2 shows a principle diagram of an electric bridge circuit section constructed using the differential pressure sensor shown in FIG. 1. FIG. 3 is a block diagram of a conventionally known two-wire differential pressure transmission system. FIG. 4 shows a schematic configuration of a two-wire differential pressure transmitter in which the present invention can be implemented. FIG. 5 shows a detailed configuration of the temperature error compensation circuit included in the differential pressure converter in the embodiment of the present invention shown in FIG. FIG. 6A is an explanatory diagram of the configuration of one sliding wire resistance of a voltage/current converter which is a part of the temperature error compensation circuit of a differential pressure converter in which the present invention can be implemented, and FIG. 6B
represents the correspondence between the contact position of the slider sliding on the sliding wire resistance and the voltage on the slider. FIG. 7 is an equivalent circuit showing the configuration of the output circuit portion of the voltage/current converter included in the temperature error compensation circuit. FIG. 8 shows the configuration of a circuit section related to zero point error compensation in a differential pressure converter section in which the present invention can be implemented. FIG. 9 shows a circuit configuration of a portion related to span error compensation in a differential pressure converter portion in which the present invention can be implemented. FIG. 10 is a diagram showing the input/output characteristics of the differential pressure converter. In FIG. 4, PD...differential pressure converter, PD1 ...bridge circuit part of the differential pressure converter, PD2 ...operating current control circuit part of the differential pressure converter, TC...temperature error compensation circuit,
I/V...Current voltage conversion circuit, S1 ...Summing point, S2 ...Summing point, I R ...Reference current, RV1 ...First sliding line resistance, d1
...First slider, RV 2 ...Second sliding line resistance, d 2 ...Second
Slider, R Z ...first output resistance, R S ...second output resistance.

Claims (1)

【特許請求の範囲】 １ 差圧により変位する可動電極に対向して配置
された一対の固定電極との間で形成された一対の
静電容量の差に対応する出力電流を加算点に出力
する差圧／電流変換器と、 この加算点から出力される信号を入力してこれ
を増幅し前記差圧に対応する所定の電流信号に変
換して出力する変換回路と、 一端を基準電位点に接続し他端に周囲温度と基
準温度との差に比例する第１出力電圧を発生する
第１電圧源と、一端を前記基準電位点に接続し他
端に前記第１出力電圧と反対極性の出力電圧を発
生する第２電圧源と、前記第１電圧源と前記第２
電圧源のそれぞれの他端の間に接続された滑り線
抵抗と、この滑り線抵抗の摺動子に一端が接続さ
れ所定の抵抗値を有する出力抵抗とを有し、この
出力抵抗の他端を出力端として前記加算点に接続
した温度誤差補償回路とを具備し、 前記摺動子の滑り線抵抗上の接触位置を選択的
に設定して前記加算点に零点誤差補償電流を供給
することにより前記差圧／電流変換器に発生する
零点誤差電流を補償することを特徴とする差圧伝
送器。 ２ 差圧により変位する可動電極に対向して配置
された一対の固定電極との間で形成された一対の
静電容量の差に対応する出力電流を出力する差
圧／電流変換器と、 この出力電流が入力されこれを増幅して前記差
圧に対応する所定の電流信号に変換して出力する
変換回路と、 一端を基準電位点に接続し他端に周囲温度と基
準温度との差に比例する第１出力電圧を発生する
第１電圧源と、一端を前記基準電位点に接続し他
端に前記第１出力電圧と反対極性の出力電圧を発
生する第２電圧源と、前記第１電圧源と前記第２
電圧源のそれぞれの他端の間に接続された滑り線
抵抗と、この滑り線抵抗の摺動子に一端が接続さ
れ所定の抵抗値を有する出力抵抗とを有し、この
出力抵抗の他端からスパン誤差補償電流を出力す
る温度誤差補償回路と、 前記差圧／電流変換器における前記一対の静電
容量の和に対応する直流電流と基準電流との加算
点に前記スパン誤差補償電流が印加され、この加
算点での各電流の代数演算の結果を増幅して前記
基準電流に対応した前記直流電流になるように制
御する制御手段とを具備し、 前記摺動子の滑り線抵抗上の接触位置を選択的
に設定して任意の周囲温度において前記差圧に対
する前記差圧／電流変換器の出力電流と基準温度
における前記差圧に対する前記差圧／電流変換器
の出力電流との差を実質的に零に減ずるようにし
たことを特徴とする差圧伝送器。 ３ 差圧により変位する可動電極に対向して配置
された一対の固定電極との間で形成された一対の
静電容量の差に対応する出力電流を第１加算点に
出力する差圧／電流変換器と、 この第１加算点から出力される信号を入力して
これを増幅し前記差圧に対応する所定の電流信号
に変換して出力する変換回路と、 一端を基準電位点に接続し他端に周囲温度と基
準温度との差に比例する第１出力電圧を発生する
第１電圧源と、一端を前記基準電位点に接続し他
端に前記第１出力電圧と反対極性の出力電圧を発
生する第２電圧源と、前記第１電圧源と前記第２
電圧源のそれぞれの他端の間に接続された第１滑
り線抵抗と、この第１滑り線抵抗の第１摺動子に
一端が接続され他端から零点誤差補償電流を前記
第１加算点に出力する所定抵抗値を有する第１出
力抵抗と、前記第１滑り線抵抗と並列に接続され
た第２滑り線抵抗と、この第２滑り線抵抗の第２
摺動子に一端が接続され他端からスパン誤差補償
電流を第２加算点に出力する所定抵抗値を有する
第２出力抵抗とよりなる温度誤差補償回路とを具
備し、 前記第１摺動子の滑り線抵抗上の接触位置を選
択的に設定して前記差圧／電流変換器に生ずる零
点誤差電流を補償すると共に前記第２摺動子の前
記第２滑り線抵抗上の接触位置を選択的に設定し
て任意の周囲温度において前記差圧に対する前記
差圧／電流変換器の出力電流と基準温度における
前記差圧に対する前記差圧／電流変換器の出力電
流との差を実質的に零に減ずるようにしたことを
特徴とする差圧伝送器。[Claims] 1. An output current corresponding to the difference in capacitance of a pair formed between a movable electrode that is displaced by differential pressure and a pair of fixed electrodes placed opposite to each other is output to a summing point. a differential pressure/current converter, a conversion circuit that inputs the signal output from this addition point, amplifies it, converts it into a predetermined current signal corresponding to the differential pressure, and outputs it; one end connected to a reference potential point. a first voltage source that is connected to the reference potential point at one end and generates a first output voltage proportional to the difference between the ambient temperature and a reference temperature at the other end; a second voltage source that generates an output voltage, the first voltage source and the second voltage source;
It has a sliding wire resistor connected between the other ends of each of the voltage sources, and an output resistor having one end connected to the slider of the sliding wire resistor and having a predetermined resistance value, and the other end of the output resistor. and a temperature error compensation circuit connected to the addition point as an output terminal, selectively setting a contact position on the sliding wire resistance of the slider to supply a zero point error compensation current to the addition point. A differential pressure transmitter comprising: compensating for a zero point error current generated in the differential pressure/current converter. 2. A differential pressure/current converter that outputs an output current corresponding to the difference in capacitance between a pair of fixed electrodes arranged opposite to a movable electrode that is displaced by differential pressure; A conversion circuit receives an output current, amplifies it, converts it to a predetermined current signal corresponding to the differential pressure, and outputs it, and a converter circuit that connects one end to a reference potential point and the other end to the difference between the ambient temperature and the reference temperature. a first voltage source that generates a proportional first output voltage; a second voltage source that has one end connected to the reference potential point and that generates an output voltage of opposite polarity to the first output voltage at the other end; voltage source and said second
It has a sliding wire resistor connected between the other ends of each of the voltage sources, and an output resistor having one end connected to the slider of the sliding wire resistor and having a predetermined resistance value, and the other end of the output resistor. a temperature error compensation circuit that outputs a span error compensation current from the differential pressure/current converter; and a temperature error compensation circuit that applies the span error compensation current to a summation point of a reference current and a direct current corresponding to the sum of the pair of capacitances in the differential pressure/current converter. and control means for amplifying the results of algebraic calculation of each current at the addition point to control the direct current to become the direct current corresponding to the reference current, The contact position is selectively set to determine the difference between the output current of the differential pressure/current converter for the differential pressure at a given ambient temperature and the output current of the differential pressure/current converter for the differential pressure at a reference temperature. A differential pressure transmitter characterized in that the pressure is reduced to substantially zero. 3 Differential pressure/current that outputs an output current corresponding to the difference in capacitance of a pair formed between a movable electrode that is displaced by differential pressure and a pair of fixed electrodes placed opposite to each other to the first summing point. a converter; a conversion circuit that inputs the signal output from the first summing point, amplifies it, converts it into a predetermined current signal corresponding to the differential pressure, and outputs the signal; one end of which is connected to a reference potential point; A first voltage source that generates a first output voltage proportional to the difference between the ambient temperature and a reference temperature at the other end, and an output voltage having one end connected to the reference potential point and having the opposite polarity to the first output voltage at the other end. a second voltage source that generates a
A first sliding line resistor is connected between the other ends of the voltage source, and one end is connected to the first slider of the first sliding line resistor, and the zero point error compensation current is applied from the other end to the first summing point. a first output resistor having a predetermined resistance value to be output to, a second slip line resistance connected in parallel with the first slip line resistance, and a second output resistance of the second slip line resistance.
a temperature error compensation circuit comprising a second output resistor having one end connected to the slider and having a predetermined resistance value that outputs a span error compensation current from the other end to a second addition point, the first slider; selectively setting a contact position on the sliding line resistance of the second slider to compensate for a zero point error current occurring in the differential pressure/current converter, and selecting a contact position of the second slider on the second sliding line resistance. setting the difference between the output current of the differential pressure/current converter for the differential pressure at a given ambient temperature and the output current of the differential pressure/current converter for the differential pressure at a reference temperature to be substantially zero. A differential pressure transmitter characterized in that the pressure is reduced to .
JP58038640A 1983-03-09 1983-03-09 Differential pressure transmitting device Granted JPS59163515A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP58038640A JPS59163515A (en) 1983-03-09 1983-03-09 Differential pressure transmitting device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP58038640A JPS59163515A (en) 1983-03-09 1983-03-09 Differential pressure transmitting device

Publications (2)

Publication Number Publication Date
JPS59163515A JPS59163515A (en) 1984-09-14
JPH0326322B2 true JPH0326322B2 (en) 1991-04-10

Family

ID=12530837

Family Applications (1)

Application Number Title Priority Date Filing Date
JP58038640A Granted JPS59163515A (en) 1983-03-09 1983-03-09 Differential pressure transmitting device

Country Status (1)

Country Link
JP (1) JPS59163515A (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3786487T2 (en) * 1986-05-05 1993-11-18 Texas Instruments Inc High precision sensor.
EP0711976B1 (en) * 1994-11-11 2001-07-04 Endress + Hauser Gmbh + Co. Arrangement for linearization and temperature compensation of sensor signals

Also Published As

Publication number Publication date
JPS59163515A (en) 1984-09-14

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