JPH1186177A - Two-wire system signal transmitter - Google Patents
Two-wire system signal transmitterInfo
- Publication number
- JPH1186177A JPH1186177A JP24379197A JP24379197A JPH1186177A JP H1186177 A JPH1186177 A JP H1186177A JP 24379197 A JP24379197 A JP 24379197A JP 24379197 A JP24379197 A JP 24379197A JP H1186177 A JPH1186177 A JP H1186177A
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- Prior art keywords
- current
- transistor
- emitter
- resistor
- signal transmitter
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、負荷側から２本の
伝送線を介して伝送電流の供給を受けて測定すべき物理
量をセンサにより電気信号に変換しこれを信号処理して
負荷側に先の伝送電流を変化させて伝送する２線式信号
伝送器に係る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load receiving device which receives a transmission current through two transmission lines, converts a physical quantity to be measured into an electric signal by a sensor, processes the signal into an electric signal, and performs signal processing on the signal. The present invention relates to a two-wire signal transmitter that transmits a signal by changing the transmission current.
【０００２】特に、測定器の誤接続による過大電流の流
入が防止出来て、回路保護が出来て信頼性が向上され、
過大電流による発熱が防止出来て、安全性が向上された
２線式信号伝送器に関するものである。In particular, it is possible to prevent an excessive current from flowing due to erroneous connection of a measuring instrument, thereby protecting a circuit and improving reliability.
The present invention relates to a two-wire signal transmitter with improved safety by preventing heat generation due to excessive current.
【０００３】[0003]
【従来の技術】図３は従来の２線式信号伝送器の全体構
成を示すブロック図である。直流電源Ｅb と負荷抵抗Ｒ
L とは直列に接続されて負荷端Ｔ1 、Ｔ2 に接続されて
いる。２線式信号伝送器１０の出力端Ｔ3 、Ｔ4 はこれ
等の負荷端Ｔ1 、Ｔ2 と伝送線Ｌ1 、Ｌ2 で接続されて
いる。2. Description of the Related Art FIG. 3 is a block diagram showing the general structure of a conventional two-wire signal transmitter. DC power supply Eb and load resistance R
L is connected in series and connected to load terminals T 1 and T 2 . Output terminals T 3 and T 4 of the two-wire signal transmitter 10 are connected to these load terminals T 1 and T 2 by transmission lines L 1 and L 2 .
【０００４】出力端Ｔ3 、Ｔ4 には、コレクタとベ−ス
とが接続されたトランジスタＱ1 と、トランジスタＱ2
のコレクタとエミッタと、抵抗Ｒ1と、ダイオードＤ
1と、帰還抵抗Ｒf とが直列に接続されている。Output terminals T 3 and T 4 are connected to a transistor Q 1 having a collector and a base connected thereto, and a transistor Q 2 having a collector and a base connected thereto.
The collector and the emitter, and a resistor R 1, a diode D
1 and the feedback resistor Rf are connected in series.
【０００５】トランジスタＱ1 のエミッタとコレクタと
の間には起動用の抵抗Ｒ2が並列に接続され、ダイオー
ドＤ1と帰還抵抗Ｒf との接続点は共通電位点ＣＯＭに
接続されている。[0005] Between the transistors to Q 1 emitter and collector connected in parallel with resistor R 2 for starting connection point of the diodes D 1 and the feedback resistor R f is connected to the common potential point COM.
【０００６】そして、トランジスタＱ1のコレクタと、
ダイオードＤ1及び帰還抵抗Ｒfとの間にはツエナ−ダイ
オ−ドＤZが接続され、このツエナ−ダイオ−ドＤZの両
端に、ほぼ一定な定電圧Ｖcを発生させている。[0006] Then, the collector of the transistor Q 1,
Zener Between the diode D 1 and the feedback resistor R f - diode - de D Z is connected, the Zener - diode - across the de D Z, is generating a substantially constant constant voltage Vc.
【０００７】この定電圧Ｖc は、偏差増幅器Ｑ3、信号
処理回路１、センサ２などの回路電源として供給され
る。信号処理回路１は、例えば、差圧或いは圧力などの
物理量をセンサ２により電気信号に変換し、これに直線
性補正などの信号処理を施して抵抗Ｒ3を介して偏差増
幅器Ｑ3の非反転入力端（＋）に出力する。The constant voltage Vc is supplied as a circuit power supply for the deviation amplifier Q 3 , the signal processing circuit 1 and the sensor 2. The signal processing circuit 1 converts a physical quantity such as a differential pressure or a pressure into an electric signal by the sensor 2, performs signal processing such as linearity correction on the converted signal, and performs non-inversion of the deviation amplifier Q 3 via the resistor R 3. Output to input terminal (+).
【０００８】さらに、偏差増幅器Ｑ3の非反転入力端
（＋）には、定電圧Ｖcと帰還抵抗Ｒfの両端に発生した
帰還電圧ｅfを抵抗Ｒ4、Ｒ5で分圧した分圧電圧が印加
されている。Furthermore, the non-inverting input of the error amplifier Q 3 (+), the constant voltage Vc and the feedback resistor R f resistor feedback voltage e f generated at both ends of R 4, R 5 in dividing the partial pressure Voltage is applied.
【０００９】その反転入力端（−）には、定電圧Ｖcを
抵抗Ｒ6とＲ7で分圧した分圧電圧がバイアスとして印加
されている。そして、偏差増幅器Ｑ3の出力端に発生し
た出力電圧は抵抗Ｒ8を介してトランジスタＱ2のベース
に印加されている。[0009] The inverting input terminal (-), the dividing the divided voltage of the constant voltage Vc by the resistor R 6 and R 7 is applied as a bias. The output voltage generated at the output terminal of the error amplifier Q 3 are being applied to the base of the transistor Q 2 through a resistor R 8.
【００１０】次に、以上のように構成された２線式信号
伝送器１０の、動作について説明する。起動時には抵抗
Ｒ2を介してツエナ−ダイオ−ドＤZに伝送電流Ｉ0 を流
して、定電圧Ｖcを発生させる。Next, the operation of the two-wire signal transmitter 10 configured as described above will be described. Zener during startup via a resistor R 2 - diode - by passing a transmission current I 0 to the de D Z, generates a constant voltage Vc.
【００１１】この定電圧Ｖcにより、信号処理回路１に
回路電源が供給され、センサ２で検出された電気信号
は、例えば内蔵のマイクロコンピュ−タの制御の下に信
号処理がなされてセンサ信号ｅsとして抵抗Ｒ3を介して
偏差増幅器Ｑ3の非反転入力端（＋）に出力される。The circuit power is supplied to the signal processing circuit 1 by the constant voltage Vc, and the electric signal detected by the sensor 2 is subjected to signal processing under the control of a built-in microcomputer, for example, to generate a sensor signal es. It is output to the non-inverting input of difference amplifier Q 3 (+) through a resistor R 3 as.
【００１２】この結果、センサ信号ｅsに対応してトラ
ンジスタＱ2 にベ−ス電圧が印加され、そのコレクタ電
流でトランジスタＱ1に電流を流し、正常に定電圧Ｖcを
確立する。[0012] Consequently, in response to the sensor signal es base transistor Q 2 - scan voltage is applied, a current flows in the collector current in the transistor Q 1, to establish a normally constant voltage Vc.
【００１３】このため、トランジスタＱ1 のエミッタと
コレクタ間に伝送線Ｌ1 、Ｌ2 に流れる伝送電流Ｉ
0（例えば、４ｍＡ〜２０ｍＡ）とほぼ同じ電流が流さ
れる。この電流の大部分はツエナ−ダイオ−ドＤZと帰
還抵抗Ｒf を介して負荷抵抗ＲLに流れる。Therefore, the transmission current I flowing through the transmission lines L 1 and L 2 between the emitter and the collector of the transistor Q 1
0 (for example, 4 mA to 20 mA) flows. Most of this current Zener - diode - via de D Z and the feedback resistor R f flows in the load resistor RL.
【００１４】この結果、帰還抵抗Ｒf に伝送電流Ｉ0 に
対応した帰還電圧ｅf が発生するが、偏差増幅器Ｑ3 は
帰還電圧ｅf とセンサ信号ｅsに対応する電圧が等しく
なるようにトランジスタＱ2 を介してトランジスタＱ1
のコレクタ電流を制御する。 従って、伝送電流Ｉ0 はセ
ンサの出力信号に対応する電流となる。As a result, the feedback resistor Rf The transmission current I0 To
Corresponding feedback voltage ef Occurs, but the deviation amplifier QThree Is
Feedback voltage ef And the voltage corresponding to the sensor signal es are equal
Transistor QTwo Through the transistor Q1
To control the collector current. Therefore, the transmission current I0 Is
It becomes a current corresponding to the output signal of the sensor.
【００１５】なお、トランジスタＱ1 、Ｑ2 ツエナ−ダ
イオ−ドＤZによるこの様な構成によれば、トランジス
タＱ2 に流れる電流は極めて少ないので、ここでの電流
消費が少なく、ツエナ−ダイオ−ドＤZに大部分の電流
を流すことができ、信号処理回路１に消費電流の大きい
マイクロコンピュ−タを搭載するときには、伝送電流Ｉ
0 を電源パワ−として有効に利用できる。According to such a configuration using the transistors Q 1 and Q 2 and the Zener diode D Z , the current flowing through the transistor Q 2 is extremely small, so that the current consumption is small and the Zener diode is not used. de D Z to most of the current that can flow in a large microcomputer current consumption in the signal processing circuit 1 - when mounting the motor, the transmission current I
0 can be effectively used as power supply power.
【００１６】[0016]
【発明が解決しようとする課題】一般に、このような装
置においては、装置の機能上必要な場合は、出力回路と
信号処理回路とは絶縁される。Generally, in such a device, the output circuit and the signal processing circuit are insulated when the function of the device is necessary.
【００１７】しかし、装置の機能上絶縁しなくても良い
場合は、装置の製造コストを出来るだけ低減するために
絶縁が省かれることになる。しかしながら、このような
装置において、装置の状態を調べる為に、測定器を接続
した場合に問題となる事が分かった。However, if the device does not need to be insulated for its function, the insulation is omitted in order to reduce the manufacturing cost of the device as much as possible. However, it has been found that such a device poses a problem when a measuring instrument is connected to check the state of the device.
【００１８】すなわち、図４に示す如く、二線式伝送器
１０に測定器Ａ、具体的には、例えばオシロスコープ、
を接続し、更に、その測定器Ａの接続端子Ａ1が接地端
子Ａ2につながっている場合、接地を通して電流Ｉaが流
れ、帰還抵抗Ｒfに電位差が生じ無いため、電流をより
多く流れるようにコントロールされ、トランジスタ
Ｑ1、または内部の回路が発熱し、破壊されてしまう。That is, as shown in FIG. 4, a two-wire transmitter 10 has a measuring device A, specifically, for example, an oscilloscope,
Further, when the connection terminal A 1 of the measuring instrument A is connected to the ground terminal A 2 , the current Ia flows through the ground, and there is no potential difference in the feedback resistor Rf , so that more current flows. As a result, the transistor Q 1 or the internal circuit generates heat and is destroyed.
【００１９】本発明は、この問題点を、解決するもので
ある。本発明の目的は、測定器の誤接続による過大電流
の流入が防止出来て、回路保護が出来て信頼性が向上さ
れ、過大電流による発熱が防止出来て、安全性が向上さ
れた２線式信号伝送器を提供するにある。The present invention solves this problem. An object of the present invention is to prevent the flow of excessive current due to erroneous connection of a measuring instrument, to protect a circuit and improve reliability, to prevent heat generation due to excessive current, and to improve the safety of a two-wire system. Signal transmitter.
【００２０】[0020]
【課題を解決するための手段】この目的を達成するため
に、本発明は、 （１）負荷側から２本の伝送線を介して伝送電流の供給
を受けて測定すべき物理量をセンサにより電気信号に変
換しこれを信号処理して負荷側に前記伝送電流を変化さ
せて伝送する２線式信号伝送器において、前記伝送電流
に比例する帰還電圧を発生させる帰還抵抗と、前記電気
信号に対応するセンサ信号に前記帰還電圧が一致するよ
うにベース電流が制御されて前記帰還抵抗にエミッタ電
流を流す出力トランジスタと、この出力トランジスタの
コレクタ電流で前記伝送電流が制御される第１のトラン
ジスタと、この第１のトランジスタのエミッタに直列に
挿入された抵抗と、この抵抗の両端にそれぞれエミッタ
とベースとが並列に接続されコレクタが前記出力トラン
ジスタのコレクタに接続される第２のトランジスタとを
具備したことを特徴とする２線式信号伝送器。 （２）前記第２のトランジスタのエミッタに直列に挿入
された抵抗を具備したことを特徴とする請求項１記載の
２線式信号伝送器。 を構成したものである。In order to achieve this object, the present invention relates to (1) receiving a supply of a transmission current through two transmission lines from a load side, and measuring a physical quantity to be measured by a sensor. A two-wire signal transmitter that converts the signal into a signal, processes the signal, and changes and transmits the transmission current to the load side, wherein a feedback resistor that generates a feedback voltage proportional to the transmission current; An output transistor whose base current is controlled so that the feedback voltage coincides with the sensor signal to flow an emitter current through the feedback resistor; a first transistor whose transmission current is controlled by a collector current of the output transistor; A resistor inserted in series with the emitter of the first transistor, and an emitter and a base connected in parallel to both ends of the resistor, and a collector connected to the output transistor A second transistor connected to the collector of the star. (2) The two-wire signal transmitter according to claim 1, further comprising a resistor inserted in series with the emitter of the second transistor. It is what constituted.
【００２１】[0021]
【作 用】帰還抵抗により負荷側からの伝送電流に比例
する帰還電圧を発生させ、出力トランジスタはセンサ信
号に先の帰還電圧が一致するようにベース電流を制御し
て先の帰還抵抗にエミッタ電流を流す。[Function] The feedback resistor generates a feedback voltage proportional to the transmission current from the load side, and the output transistor controls the base current so that the previous feedback voltage matches the sensor signal, and the emitter current is supplied to the previous feedback resistor. Flow.
【００２２】一方、測定器の誤接続により、過大電流が
回路に流入しょうとしても、第２のトランジスタは、第
１のトランジスタのエミッタに直列に挿入された抵抗の
抵抗値と、この抵抗を流れる電流の積が、ベースーエミ
ッタ間電圧より大になるとオンになり、第１のトランジ
スタのベースーエミッタ間電圧が小さくなり電流が制限
される。On the other hand, even if an excessive current tries to flow into the circuit due to an erroneous connection of the measuring instrument, the second transistor flows through this resistor and the resistance value of the resistor inserted in series with the emitter of the first transistor. When the product of the current is larger than the voltage between the base and the emitter, the transistor is turned on, and the voltage between the base and the emitter of the first transistor is reduced to limit the current.
【００２３】すなわち、第２のトランジスタのエミッタ
電流は、出力トランジスタのエミッタに挿入された抵抗
により制限されるため、出力電流と比較して十分小さ
く、従って、第１のトランジスタのエミッタに直列に挿
入された抵抗を流れる電流は、出力電流と略等しく成
る。That is, since the emitter current of the second transistor is limited by the resistance inserted into the emitter of the output transistor, it is sufficiently smaller than the output current, and therefore, is inserted in series with the emitter of the first transistor. The current flowing through the resistor becomes substantially equal to the output current.
【００２４】従って、出力電流と第１のトランジスタの
エミッタに直列に挿入された抵抗の抵抗値との積は、ほ
ぼ第２のトランジスタのベースーエミッタ間電圧とな
り、電流が制限される。以下、実施例に基づき詳細に説
明する。Accordingly, the product of the output current and the resistance value of the resistor inserted in series with the emitter of the first transistor is substantially equal to the base-emitter voltage of the second transistor, and the current is limited. Hereinafter, a detailed description will be given based on embodiments.
【００２５】[0025]
【発明の実施の形態】図１は本発明の一実施例の要部構
成説明図である。図において、図３と同一記号の構成は
同一機能を表わす。以下、図３と相違部分のみ説明す
る。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a main part of an embodiment of the present invention. In the figure, the configuration of the same symbol as in FIG. 3 represents the same function. Hereinafter, only differences from FIG. 3 will be described.
【００２６】図３において、出力端Ｔ3 には、抵抗Ｒc
を介してトランジスタＱ1のエミッタが接続されてい
る。この抵抗Ｒcの両端にそれぞれエミッタとベースと
が並列に接続され、コレクタが出力トランジスタＱ2の
コレクタに接続されるトランジスタＱCが接続されてい
る。In FIG. 3, a resistor R c is connected to an output terminal T 3.
The emitter of the transistor Q 1 is connected via a. The both ends emitter resistor R c and a base connected in parallel, the transistor Q C having a collector connected to the collector of the output transistor Q 2 is connected.
【００２７】以上の構成において、トランジスタＱ
Cは、 Ｒc×Ｉc＞ＶBE（≒０．６Ｖ） になるとオンになり、トランジスタＱ1のＶBEが小さく
なり電流が制限される。In the above configuration, the transistor Q
C is turned on when R c × I c > V BE (≒ 0.6 V), and the V BE of the transistor Q 1 is reduced to limit the current.
【００２８】すなわち、トランジスタＱCのエミッタ電
流は、抵抗Ｒ1により制限されるため、出力電流Ｉ0と比
較して十分小さく、従って、Ｉc≒Ｉ0であるから、 Ｉ0×Ｒc≒ＶBE（≒０．６Ｖ） で電流が制限されることになる。[0028] That is, the emitter current of the transistor Q C is because it is limited by the resistor R 1, sufficiently smaller than the output current I 0, therefore, because it is I c ≒ I 0, I 0 × R c ≒ The current is limited by V BE (≒ 0.6 V).
【００２９】この結果、 （１）測定器の接続による本発明装置への過大電流の流
入が防止出来、回路保護が出来て信頼性が向上出来る二
線式信号伝送器が得られる。また、過大電流による発熱
が防止出来て、安全性が向上された二線式信号伝送器が
得られる。As a result, (1) it is possible to obtain a two-wire signal transmitter capable of preventing an excessive current from flowing into the apparatus of the present invention due to the connection of the measuring instrument, protecting the circuit and improving the reliability. Further, a heat generation due to an excessive current can be prevented, and a two-wire signal transmitter with improved safety can be obtained.
【００３０】（２）トランジスタのＶBEは高温になるほ
ど小さくなる。したがって、高温になるほど、制限され
る電流の値は小さくなる。すなわち、周囲温度が高温に
なるほど発熱が小さくなる、従って、より効果的な回路
保護が出来て信頼性が向上出来る二線式信号伝送器が得
られる。(2) V BE of the transistor decreases as the temperature increases. Therefore, the higher the temperature is, the smaller the value of the limited current is. That is, the lower the ambient temperature is, the smaller the amount of heat generated is. Therefore, a two-wire signal transmitter that can provide more effective circuit protection and improve reliability can be obtained.
【００３１】（３）なお、本発明の保護回路が動作しな
い通常の状態で、本発明の保護回路による電圧降下はＶ
BE（≒０．６Ｖ）より必ず小さい。つまり、通常の動作
状態において、本発明の保護回路を追加したことによる
影響が小さい二線式信号伝送器が得られる。(3) In a normal state in which the protection circuit of the present invention does not operate, the voltage drop by the protection circuit of the present invention is V
Be smaller than BE (≒ 0.6V). That is, in a normal operation state, a two-wire signal transmitter which is less affected by the addition of the protection circuit of the present invention is obtained.
【００３２】図２は本発明の他の実施例の要部構成説明
図である。本実施例においては、トランジスタＱCのエ
ミッタに直列に抵抗ＲEが挿入されている。トランジス
タＱCのエミッタに直列に抵抗ＲEが挿入されたので、耐
サージ特性が良好な二線式信号伝送器が得られる。FIG. 2 is an explanatory diagram of a main part configuration of another embodiment of the present invention. In this embodiment, the resistance in series R E is inserted into the emitter of the transistor Q C. Since the transistor Q C of the emitter to a resistor in series with R E is inserted, the anti-surge characteristics good two-wire signal transmitter can be obtained.
【００３３】[0033]
【発明の効果】以上、詳細に説明したように、本発明の
請求項１によれば、 （１）測定器の接続による本発明装置への過大電流の流
入が防止出来、回路保護が出来て信頼性が向上出来る二
線式信号伝送器が得られる。また、過大電流による発熱
が防止出来て、安全性が向上された二線式信号伝送器が
得られる。As described above in detail, according to the first aspect of the present invention, (1) it is possible to prevent an excessive current from flowing into the apparatus of the present invention due to connection of a measuring instrument, and to protect a circuit. A two-wire signal transmitter with improved reliability can be obtained. Further, a heat generation due to an excessive current can be prevented, and a two-wire signal transmitter with improved safety can be obtained.
【００３４】（２）トランジスタのベースーエミッタ電
圧は、高温になるほど小さくなる。したがって、高温に
なるほど、制限される電流の値は小さくなる。すなわ
ち、周囲温度が高温になるほど発熱が小さくなる、従っ
て、より効果的な回路保護が出来て信頼性が向上出来る
二線式信号伝送器が得られる。(2) The base-emitter voltage of the transistor decreases as the temperature increases. Therefore, the higher the temperature is, the smaller the value of the limited current is. That is, the lower the ambient temperature is, the smaller the amount of heat generated is. Therefore, a two-wire signal transmitter that can provide more effective circuit protection and improve reliability can be obtained.
【００３５】（３）なお、本発明の保護回路が動作しな
い通常の状態で、本発明の保護回路による電圧降下はベ
ースーエミッタ電圧より必ず小さい。つまり、通常の動
作状態において、本発明の保護回路を追加したことによ
る影響が小さい二線式信号伝送器が得られる。(3) In a normal state where the protection circuit of the present invention does not operate, the voltage drop by the protection circuit of the present invention is always smaller than the base-emitter voltage. That is, in a normal operation state, a two-wire signal transmitter which is less affected by the addition of the protection circuit of the present invention is obtained.
【００３６】本発明の請求項２によれば、加えるに、耐
サージ特性が良好な二線式信号伝送器が得られる。According to the second aspect of the present invention, in addition, a two-wire signal transmitter having a good surge resistance can be obtained.
【００３７】従って、本発明によれば、測定器の誤接続
による過大電流の流入が防止出来て、回路保護が出来て
信頼性が向上され、過大電流による発熱が防止出来て、
安全性が向上された２線式信号伝送器を実現することが
出来る。Therefore, according to the present invention, it is possible to prevent an excessive current from flowing due to erroneous connection of a measuring instrument, to protect a circuit, to improve reliability, and to prevent heat generation due to an excessive current.
A two-wire signal transmitter with improved safety can be realized.
【図１】本発明の一実施例の構成説明図図である。FIG. 1 is a diagram illustrating the configuration of an embodiment of the present invention.
【図２】本発明の他の実施例の構成説明図図である。FIG. 2 is a diagram illustrating the configuration of another embodiment of the present invention.
【図３】従来より一般に使用されている従来例の構成説
明図図である。FIG. 3 is an explanatory diagram of a configuration of a conventional example generally used in the related art.
【図４】図３の動作説明図である。FIG. 4 is an operation explanatory diagram of FIG. 3;
１ 信号処理回路 ２ センサ Ｅb 直流電源 Ｑ1 トランジスタ Ｑ2 トランジスタ Ｑ3 偏差増幅器 Ｑc トランジスタ ＲL 負荷抵抗 Ｒc 抵抗 ＲE 抵抗First signal processing circuit 2 sensor E b DC power source Q 1 transistor Q 2 transistor Q 3 deviation amplifier Q c transistor RL the load resistance R c resistance R E resistance
───────────────────────────────────────────────────── フロントページの続き (72)発明者 本堂 雅則 東京都武蔵野市中町２丁目９番32号 横河 電機株式会社内 (72)発明者 筒井 弘英 東京都武蔵野市中町２丁目９番32号 横河 電機株式会社内 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanori Hondo 2-9-132 Nakamachi, Musashino-shi, Tokyo Inside Yokogawa Electric Corporation (72) Inventor Hirohide Tsutsui 2-9-132 Nakamachi, Musashino-shi, Tokyo Yokogawa Electric Corporation
Claims (2)
の供給を受けて測定すべき物理量をセンサにより電気信
号に変換しこれを信号処理して負荷側に前記伝送電流を
変化させて伝送する２線式信号伝送器において、 前記伝送電流に比例する帰還電圧を発生させる帰還抵抗
と、 前記電気信号に対応するセンサ信号に前記帰還電圧が一
致するようにベース電流が制御されて前記帰還抵抗にエ
ミッタ電流を流す出力トランジスタと、 この出力トランジスタのコレクタ電流で前記伝送電流が
制御される第１のトランジスタと、 この第１のトランジスタのエミッタに直列に挿入された
抵抗と、 この抵抗の両端にそれぞれエミッタとベースとが並列に
接続されコレクタが前記出力トランジスタのコレクタに
接続される第２のトランジスタとを具備したことを特徴
とする２線式信号伝送器。1. A sensor receives a supply of a transmission current from two loads via a transmission line, converts a physical quantity to be measured into an electric signal by a sensor, processes the electric signal, and changes the transmission current to the load side. In a two-wire signal transmitter for transmitting a signal, a feedback resistor for generating a feedback voltage proportional to the transmission current; and a base current controlled such that the feedback voltage matches a sensor signal corresponding to the electric signal, and An output transistor that supplies an emitter current to a feedback resistor; a first transistor whose transmission current is controlled by a collector current of the output transistor; a resistor inserted in series with the emitter of the first transistor; A second transistor having an emitter and a base connected in parallel at both ends and a collector connected to the collector of the output transistor; 2 wire signal transmitter, characterized in that.
に挿入された抵抗を具備したことを特徴とする請求項１
記載の２線式信号伝送器。2. The semiconductor device according to claim 1, further comprising a resistor inserted in series with an emitter of said second transistor.
A two-wire signal transmitter according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24379197A JP3422015B2 (en) | 1997-09-09 | 1997-09-09 | Two-wire signal transmitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24379197A JP3422015B2 (en) | 1997-09-09 | 1997-09-09 | Two-wire signal transmitter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1186177A true JPH1186177A (en) | 1999-03-30 |
| JP3422015B2 JP3422015B2 (en) | 2003-06-30 |
Family
ID=17109016
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24379197A Expired - Fee Related JP3422015B2 (en) | 1997-09-09 | 1997-09-09 | Two-wire signal transmitter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3422015B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007139130A (en) * | 2005-11-21 | 2007-06-07 | Ckd Corp | Liquid pressure cylinder sensor |
| US8405534B2 (en) | 2009-10-21 | 2013-03-26 | Asahi Kasei Microdevices Corporation | Two-wire transmitter |
-
1997
- 1997-09-09 JP JP24379197A patent/JP3422015B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007139130A (en) * | 2005-11-21 | 2007-06-07 | Ckd Corp | Liquid pressure cylinder sensor |
| JP4608419B2 (en) * | 2005-11-21 | 2011-01-12 | シーケーディ株式会社 | Fluid pressure cylinder sensor |
| US8405534B2 (en) | 2009-10-21 | 2013-03-26 | Asahi Kasei Microdevices Corporation | Two-wire transmitter |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3422015B2 (en) | 2003-06-30 |
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