WO2011048786A1 - 2線式伝送器 - Google Patents
2線式伝送器 Download PDFInfo
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- WO2011048786A1 WO2011048786A1 PCT/JP2010/006136 JP2010006136W WO2011048786A1 WO 2011048786 A1 WO2011048786 A1 WO 2011048786A1 JP 2010006136 W JP2010006136 W JP 2010006136W WO 2011048786 A1 WO2011048786 A1 WO 2011048786A1
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- G—PHYSICS
- G08—SIGNALLING
- G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
- G08C19/00—Electric signal transmission systems
- G08C19/02—Electric signal transmission systems in which the signal transmitted is magnitude of current or voltage
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- the present invention relates to a two-wire transmitter that is applied to a two-wire transmitter and outputs an input signal, for example, a sensor signal detected by a sensor as an analog signal.
- the two-wire transmitter is a device that detects a physical quantity such as a flow rate or pressure and outputs a detection value (hereinafter referred to as “sensor signal”).
- sensor signal An example of a two-wire transmitter that converts a sensor signal into an analog voltage signal and outputs the analog voltage signal is the two-wire transmitter described in Patent Document 1.
- FIG. 5 is a diagram for explaining the prior art of the two-wire transmitter.
- the illustrated two-wire transmitter 10 includes an operational amplifier 1 that amplifies the sensor signals M1 and M2 output from the sensor S, and a switch 3 that switches the connection destination according to the voltage value of the sensor signal Vsns output from the operational amplifier 1. And resistive elements 5, 6, 7 connected to the switch 3.
- the two-wire transmitter 10 includes a reference voltage generator 4, a resistance element 6 connected to the switch 3, and an operational amplifier 2 whose output current Iout varies depending on the size of the resistance element 7.
- the sensor S is a sensor that detects physical quantities such as magnetism, temperature, and pressure.
- the two-wire transmitter 10 shown in FIG. 5 operates as follows.
- the operational amplifier 1 outputs a continuously changing sensor signal Vsns.
- the connection destination of the switch 3 is switched from the resistance element 6 to the resistance element 7.
- the potential difference between the output signal Vout of the operational amplifier 2 and the ground (GND) is divided by the resistive element 5, the resistive element 6 connected to the switch 3, or the resistive element 7.
- a signal corresponding to the divided potential is input to the operational amplifier 2 as a feedback signal Vfb.
- the operational amplifier 2 is generated by the reference voltage generator 4, the operational amplifier 2 operates to make the voltage values of the reference voltage Vref and the feedback signal Vfb equal.
- the operational amplifier 2 operates so as to increase the output current Iout when the voltage value of the feedback signal Vfb increases. At this time, the output signal Vout drops so that the reference voltage Vref and the voltage value of the feedback signal Vfb become equal. On the other hand, when the feedback signal Vfb decreases, the operational amplifier 2 operates to decrease the output current Iout. As a result, the output signal Vout of the operational amplifier 2 rises so that the reference voltage Vref and the feedback signal Vfb are equal.
- FIG. 6 is a diagram showing the relationship between sensor signals and output signals in a conventional two-wire transmission line. 6 represents the output signal Vout, and the horizontal axis represents the resistance R of the two-wire transmitter.
- the relationship between the resistance R of the two-wire transmitter and the output signal Vout is expressed by the following equation (1).
- R0 is the resistance value of the illustrated resistance element 5
- R is the resistance value (R1, R2) of either the resistance element 6 or the resistance element 7 selected by the switch 3.
- Vout Vref + (R0 / R) ⁇ Vref (1)
- the sensor signal Vsns output from the sensor S changes continuously. When the sensor signal Vsns exceeds a predetermined threshold, the connection destination of the switch 3 is switched from the resistance element 6 to the resistance element 7.
- the output signal Vout changes discretely even though the sensor signal Vsns continuously changes. For this reason, the conventional 2-wire transmitter cannot obtain the output signal Vout reflecting the sensor signal Vsns because the output signal Vout is not proportional to the sensor signal Vsns. Since FIG. 6 shows a case where a plurality of resistance elements other than the resistance elements 6 and 7 are provided, the values of a plurality of discrete output signals Vout are shown.
- the output signal Vout needs to be input to a CPU (Central Processing Unit: not shown) in the subsequent stage, and the output signal Vout needs to be further processed in the CPU.
- the present invention has been made in view of the above points, and by converting a sensor signal into a continuous analog signal, a signal reflecting a continuous change in the sensor signal can be obtained, and the subsequent calculation is performed.
- An object of the present invention is to provide a two-wire transmitter capable of simplifying the configuration and processing according to the above.
- an analog voltage signal (for example, the output signal V3 illustrated in FIG. 1) based on an input signal (for example, the sensor signal V1 illustrated in FIG. 1) is first transmitted.
- a two-wire transmitter for outputting to a line (for example, transmission line N1 shown in FIG. 1), wherein an intermediate potential between the first transmission line and the second transmission line (for example, transmission line N2 shown in FIG. 1) is
- An intermediate potential generation circuit (for example, the resistance elements 103 and 104 shown in FIG. 1) to be generated, an amplifier (for example, the operational amplifier 101 shown in FIG.
- a two-wire transmitter including a current generation circuit (for example, the current source 102 shown in FIG. 1) that generates a current flowing from the first transmission path to the second transmission path based on a control signal to be provided Is done.
- a current generation circuit for example, the current source 102 shown in FIG. 1 that generates a current flowing from the first transmission path to the second transmission path based on a control signal to be provided Is done.
- the first transmission line is connected to a power source (for example, Vcc illustrated in FIG. 3) via the first resistance element (for example, the resistance element 107 illustrated in FIG. 3). ) Is desirable.
- the amplifier outputs the control signal so that the input signal and the intermediate potential are equal.
- the intermediate potential signal generation circuit is a second resistance element (for example, connected in series between the first transmission line and the second transmission line). 1 and a third resistance element (for example, the resistance element 104 shown in FIG. 1), and generates the intermediate potential between the second resistance element and the third resistance element. It is desirable.
- the current generating circuit includes a current source that generates the current based on the intermediate potential.
- the analog voltage signal is preferably supplied as power to the amplifier via the first transmission line in the above-described invention.
- the two-wire transmitter of the present invention further includes a receiver (for example, the CPU receiver 106 shown in FIG. 3) connected to the first transmission line and receiving the analog voltage signal in the above-described invention. It is desirable.
- a processing circuit that converts the input signal into a digital signal and processes the digital signal (for example, the A / A shown in FIG. 4).
- the input signal is preferably a sensor signal output from a sensor (for example, the sensor S shown in FIG. 1).
- the two-wire transmitter of the present invention preferably further includes a sensor that outputs the sensor signal.
- the two-wire transmitter of the present invention further includes the first resistance element connected to the first transmission line and the power source connected to the first resistance element in the above-described invention. Is desirable.
- the intermediate potential between the transmission line and the reference transmission line and the input signal can be output to the amplifier, and an analog voltage signal can be generated based on this signal.
- the amplifier operates so that the inputted input signal is equal to the intermediate potential. For this reason, since the output of the amplifier changes in accordance with the input signal, an analog voltage signal reflecting the input signal can be obtained.
- information such as temperature, magnetism, and pressure detected by a sensor can be easily extracted from this signal. Therefore, it is possible to provide a two-wire transmitter that can obtain an input signal, for example, a signal reflecting a continuous change of a sensor signal.
- the external power source is connected to the transmission line via the first resistance element, the potential of the transmission line from which the analog voltage signal is output can be maintained appropriately. Further, it is possible to prevent the transmission line from being short-circuited with an external power source.
- the intermediate potential between the transmission line and the reference transmission line and the input signal can be output to the amplifier, and an analog voltage signal can be generated based on this signal.
- the amplifier operates so that the inputted input signal is equal to the intermediate potential. For this reason, since the output of the amplifier changes in accordance with the input signal, an analog signal reflecting the input signal can be obtained.
- the intermediate potential generation circuit includes the second resistance element and the third resistance element connected in series between the transmission line and the reference transmission line, and the second resistance element and the second resistance element Since an intermediate potential is output from between the three resistance elements, the voltage range of the output signal output from the amplifier is not limited to the reference voltage or the like.
- the current generation circuit since the current generation circuit includes a current source that generates a current based on the intermediate potential, the potential between the transmission line and the reference transmission line can be easily controlled. .
- the analog voltage signal is supplied to the amplifier via the transmission line, it is possible to simplify the circuit configuration by providing two amplifier input systems.
- the detection value detected by, for example, the sensor can be directly obtained from the analog signal output to the transmission path. For this reason, it is possible to simplify the calculation of an input signal, for example, a sensor signal, at the stage subsequent to the receiver.
- the input signal when the input signal is an analog signal, the input signal is converted into a digital signal and processed, and the processed digital signal is converted into an analog signal and output to the amplifier. it can. For this reason, for example, it is possible to easily correct an offset or sensitivity of an input signal, for example, a sensor signal, and output an analog signal having an arbitrary characteristic.
- information such as temperature, magnetism, and pressure detected by the sensor can be easily extracted.
- a compact two-wire transmitter including a sensor can be realized.
- a compact two-wire transmitter including a resistance element and a power source connected to the resistance element can be realized.
- FIG. 1 is a circuit diagram for explaining a two-wire transmitter according to the first embodiment of the present invention.
- the illustrated two-wire transmitter includes a sensor S.
- the sensor S is, for example, a sensor that detects physical quantities such as magnetism, temperature, and pressure and outputs them as a sensor signal V1.
- the sensor S may be separately provided outside the two-wire transmitter.
- the two-wire transmitter is a two-wire transmitter that converts an input signal (for example, sensor signal V1) into an analog voltage signal and outputs the analog voltage signal to the transmission line, and is between the transmission line N1 and the reference transmission line N2.
- an output signal V3 that is an analog voltage signal is generated.
- a current source 102 In such a configuration, since the intermediate potential is fed back to the operational amplifier 101, it is hereinafter referred to as a feedback signal V2 in the present embodiment.
- the operational amplifier 101 generates a signal o that controls the potential between the transmission line N1 and the reference transmission line N2 so that the input sensor signal V1 and the feedback signal V2 are equal.
- the current source 102 changes the output current I3 according to the control signal o of the operational amplifier 101.
- the intermediate potential generation circuit 100 includes a resistance element 103 and a resistance element 104 connected in series between the transmission line N1 and the reference transmission line N2, and a feedback signal V2 from between the resistance element 103 and the resistance element 104. Is output.
- the signal line of the sensor signal V1 output from the sensor S is connected to the inverting input terminal of the operational amplifier 101. Further, the signal line of the feedback signal V2 is connected to the non-inverting input terminal of the operational amplifier 101.
- the output terminal of the operational amplifier 101 is connected to the current source 102.
- the above configuration and the intermediate potential generation circuit 100 are both connected between the transmission line N1 serving as a power supply line and the reference transmission line N2, and the transmission line N1 supplies power for the output signal V3.
- the reference transmission line N2 is supplied with electric power applied to the GND potential.
- an external power source is connected to the transmission line N1 via a resistance element (not shown) so that the output signal V3 is pulled up, and the reference transmission line N2 is installed at the GND. .
- the operational amplifier 101 operates so that the sensor signal V1 and the feedback signal V2 are equal. Specifically, the operational amplifier 101 controls the current source 102 to decrease the output current I3 and increase the output voltage V3 when the sensor signal V1 increases. By this operation, the current flowing through the resistance elements 103 and 104 increases and the feedback signal V2 rises.
- the feedback signal V2 increases in accordance with the increase in the sensor signal V1, and the sensor signal V1 and the feedback signal V2 become equal. That is, the output signal V3 of the operational amplifier 101 rises so that the sensor signal V1 and the feedback signal V2 are equal.
- the operational amplifier 101 controls the current source 102 to increase the output current I3 and decrease the output voltage V3.
- the current flowing through the resistance elements 103 and 104 decreases, and the feedback signal V2 decreases. Since the increase in the output current I3 corresponds to the decrease in the sensor signal V1, the feedback signal V2 decreases in accordance with the decrease in the sensor signal V1, and the sensor signal V1 and the feedback signal V2 become equal. That is, the output signal V3 drops so that the sensor signal V1 and the feedback signal V2 are equal.
- Equation (2) The relationship between the sensor signal V1 and the output signal V3 in the above operation is expressed by the following equation (2).
- R0 is the resistance value of the resistance element 103
- R1 is the resistance value of the resistance element 104.
- V3 (1+ (R0 / R1)) ⁇ V1 Formula (2)
- FIG. 2 is a diagram illustrating the relationship between the output signal V3 and the sensor signal V1 represented by the equation (2), where the vertical axis indicates the output signal V3 and the horizontal axis indicates the sensor signal V1.
- FIG. 2 shows that the sensor signal V1 is converted into a continuous analog voltage signal, that is, the output signal V3 is proportional to the sensor signal V1.
- the feedback signal V2 related to the intermediate potential between the transmission line N1 and the reference transmission line N2 and the sensor signal V1 are output to the operational amplifier 101, and the analog voltage signal is converted based on this signal. Can be generated.
- the operational amplifier 101 controls the potential between the transmission line N1 and the reference transmission line N2 so that the input sensor signal V1 and the feedback signal V2 are equal to each other.
- the potential changes according to the sensor signal V1. For this reason, since the output of the operational amplifier 101 changes according to the sensor signal V1, an analog signal reflecting the sensor signal V1 can be obtained.
- information such as temperature, magnetism, and pressure detected by the sensor S can be easily extracted from this signal.
- FIG. 3 is a circuit diagram for explaining the two-wire transmitter according to the second embodiment of the present invention.
- the same configurations as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is partially omitted.
- Configuration The two-wire transmitter of the second embodiment is configured by connecting the receiver CPU 106 to the two-wire transmitter of the embodiment shown in FIG.
- the external power supply Vcc connected to the transmission line N1 the resistance element 107, and the GND line connected to the reference transmission line N2 are clearly shown, and a state where a two-wire transmitter is used is shown.
- the two-wire transmitter is supplied with electric power applied to the output signal V3 from the external power supply Vcc via the resistance element 107 and the transmission line N1.
- the two-wire transmitter may be configured to include the external power supply Vcc and the resistance element 107, or may be configured to be provided outside the unit without being included in the two-wire transmitter.
- the receiver CPU 106 is configured to receive the output signal V3 of the two-wire transmitter and detect the magnitude and intensity of the physical quantity detected by the sensor S.
- all current sources other than the current source 102 are collectively expressed as a current source 105 inside the two-wire transmitter, and the total sum of all currents other than the output current I3 is indicated as I4. .
- the output signal V3 of the two-wire transmitter according to the second embodiment is pulled up to the external power supply Vcc via the resistance element 107.
- the sensor signal V1 decreases and the output current I3 increases
- the voltage drop in the resistance element 107 increases and the voltage of the output signal V3 decreases.
- the output signal V3 that continuously decreases in accordance with the decrease in the sensor signal V1.
- the sensor signal V1 rises and the output current I3 decreases
- the voltage drop in the resistance element 107 decreases and the voltage of the output signal V3 increases.
- the two-wire transmitter of the second embodiment can convert the sensor signal V1 into a continuous analog voltage signal V3 that is proportional to the sensor signal V1.
- the receiver CPU 106 can obtain information on the temperature, magnetism, pressure and the like detected by the sensor S by receiving the output signal V3 from the two-wire transmitter.
- the output signal Vout is discrete and not proportional to the sensor signal Vsns.
- the output signal V3 is an analog signal proportional to the sensor signal V1, and therefore the receiver CPU can extract information contained in the sensor signal by a simple calculation.
- the voltage of the output signal Vout cannot be made equal to or lower than the reference voltage Vref in the conventional technique, there is no such restriction in the two-wire transmitter of the second embodiment.
- the voltage of the output signal V3 can be arbitrarily obtained by changing the values of the resistance element 103 and the resistance element 104.
- FIG. 4 is a circuit diagram for explaining the two-wire transmitter according to the third embodiment of the present invention.
- Configuration The A / D converter 401, the digital arithmetic unit 402, and the D / A converter 403 are added to the two-wire transmitter of the first embodiment shown in FIG. Configured.
- all current sources other than the current source 102 are collectively expressed as a current source 105 inside the two-wire transmitter, and the total sum of all currents other than the output current I3 is I4. It shall be shown as
- the sensor signal V1 is converted into a digital signal by the A / D converter 401.
- the converted digital signal is arithmetically processed by the digital arithmetic unit 402 and then converted into an analog signal V1 ′ by the D / A converter 403.
- the same processing as that of the first embodiment can be performed.
- the third embodiment is advantageous, for example, when the sensor signal offset and sensitivity are corrected and then converted into the output signal V3.
- the present invention described above can be applied to any two-wire transmitter as long as it is desirable to obtain a signal that continuously changes to reflect the detection value detected by the sensor. be able to.
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Abstract
Description
図5は、2線式伝送器の従来技術を説明するための図である。図示した2線式伝送器10は、センサSによって出力されるセンサ信号M1、M2を増幅するオペアンプ1と、オペアンプ1から出力されたセンサ信号Vsnsの電圧値に応じて接続先が切り替えられるスイッチ3と、スイッチ3に接続された抵抗素子5、6、7を備えている。また、2線式伝送器10は、基準電圧発生部4と、スイッチ3に接続される抵抗素子6、抵抗素子7の大きさによって出力電流Ioutが変化するオペアンプ2を備えている。
センサSは、例えば、磁気、温度、圧力といった物理量を検出するセンサである。
オペアンプ1は、連続的に変化するセンサ信号Vsnsを出力する。センサ信号Vsnsが所定の閾値を超えると、スイッチ3の接続先が抵抗素子6から抵抗素子7に切り替わる。オペアンプ2の出力信号Voutとグラウンド(GND)の電位差は、抵抗素子5、スイッチ3に接続されている抵抗素子6または抵抗素子7によって分圧される。分圧された電位に応じた信号は、フィードバック信号Vfbとしてオペアンプ2に入力される。オペアンプ2は、基準電圧発生部4によって生成されると基準電圧Vrefとフィードバック信号Vfbの電圧値を等しくするように動作する。
一方、フィードバック信号Vfbが低下すると、オペアンプ2は出力電流Ioutを減少させるように動作する。この結果、オペアンプ2の出力信号Voutは、基準電圧Vrefとフィードバック信号Vfbとが等しくなるように上昇する。
Vout=Vref+(R0/R)・Vref …(1)
センセSから出力されるセンサ信号Vsnsは、連続的に変化する。そして、センサ信号Vsnsが所定のしきい値を超えた場合に、スイッチ3の接続先が抵抗素子6から抵抗素子7に切り替えられる。
本発明は、上記した点に鑑みて行われたものであり、センサ信号を連続的なアナログ信号に変換することにより、センサ信号の連続的な変化を反映した信号が得られ、しかも後段の演算にかかる構成や処理を簡易化することができる2線式伝送器を提供することを目的とする。
また、本発明の2線式伝送器は、上記した発明において、前記増幅器が、入力された前記入力信号と前記中間電位とが等しくなるように、前記制御信号を出力することが望ましい。
また、本発明の2線式伝送器は、上記した発明において、前記電流生成回路が、前記中間電位に基づき、前記電流を生成する電流源を含むことが望ましい。
また、本発明の2線式伝送器は、上記した発明において、前記第1伝送路に接続され、前記アナログ電圧信号を受信する受信機(例えば図3に示したCPU受信器106)をさらに含むことが望ましい。
また、本発明の2線式伝送器は、上記した発明において、前記センサ信号を出力するセンサをさらに含むことが望ましい。
また、本発明の2線式伝送器は、上記した発明において、前記第1伝送路に接続される前記第1抵抗素子と、前記第1抵抗素子に接続される前記電源と、をさらに含むことが望ましい。
請求項3に記載の発明によれば、伝送路と基準伝送路との間の中間電位と、入力信号とを増幅器に出力し、この信号に基づいてアナログ電圧信号を生成することができる。増幅器は、入力された入力信号と中間電位とが等しくなるように動作する。このため、増幅器の出力が入力信号に応じて変化するので、入力信号を反映したアナログ信号を得ることができる。
請求項5に記載の発明によれば、電流生成回路が、中間電位に基づいて電流を生成する電流源を含むから、伝送路と基準伝送路との間の電位を簡易に制御することができる。
請求項7に記載の発明によれば、伝送路に接続される受信機をさらに設けたので、伝送路に出力されるアナログ信号から例えばセンサによって検出された検出値を直接得ることができる。このため、受信器以降の段における入力信号、例えばセンサ信号の演算を簡易化することができる。
請求項9に記載の発明によれば、センサによって検出された温度、磁気、圧力などの情報を容易に抽出することができる。
請求項10に記載の発明によれば、センサを含むコンパクトな2線式伝送器が実現できる。
請求項11に記載の発明によれば、抵抗素子及び抵抗素子に接続される電源を含むコンパクトな2線式伝送器が実現できる。
(実施形態1)
・回路構成
図1は、本発明の実施形態1の2線式伝送器を説明するための回路図である。図示した2線式伝送器は、センサSを備えている。センサSは、例えば、磁気、温度、圧力といった物理量を検出し、センサ信号V1として出力するセンサである。ここで、2線式伝送器は、センサSを備えているとしたが、2線式伝送器には含まず外部に別途センサSを備える構成としてもよい。
また、中間電位生成回路100は、伝送路N1と基準伝送路N2との間に直列接続された抵抗素子103と抵抗素子104とを含み、抵抗素子103と抵抗素子104との間からフィードバック信号V2を出力している。
なお、実施形態1の2線式伝送器は、出力信号V3がプルアップされるように外部電源が図示しない抵抗素子を介して伝送路N1に接続され、基準伝送路N2はGNDに設置される。
次に、以上述べた2線式伝送器の動作について説明する。
出力信号V3とGNDの電位差は、抵抗素子103、抵抗素子104によって分圧される。フィードバック信号V2は、抵抗素子103、抵抗素子104に分圧された電圧を示す信号である。オペアンプ101は、センサ信号V1、フィードバック信号V2が等しくなるように動作する。
具体的には、オペアンプ101は、センサ信号V1が上昇すると、出力電流I3を減少させて出力電圧V3を上昇させるように電流源102を制御する。この動作により、抵抗素子103、104に流れる電流が増加してフィードバック信号V2が上昇する。出力電流I3の減少分はセンサ信号V1の上昇分に対応しているから、センサ信号V1の上昇に応じてフィードバック信号V2が上昇し、センサ信号V1、フィードバック信号V2は等しくなる。すなわち、オペアンプ101の出力信号V3は、センサ信号V1とフィードバック信号V2とが等しくなるように上昇する。
V3=(1+(R0/R1))・V1 …式(2)
上記した式(2)によれば、本実施形態の2線式伝送器では、センサ信号V1が連続的なアナログ電圧信号に変換されることが明らかである。
図2は、式(2)によって表される出力信号V3とセンサ信号V1との関係を示した図であって、縦軸に出力信号V3を、横軸にセンサ信号V1を示している。図2によれば、センサ信号V1が連続的なアナログ電圧信号に変換される、すなわち、出力信号V3がセンサ信号V1に比例していることが分かる。
図3は、本発明の実施形態2の2線式伝送器を説明するための回路図である。なお、実施形態2では、図3中に示した構成のうち、図1に示した構成と同様の構成については同様の符号を付し、説明を一部略するものとする。
・構成
実施形態2の2線式伝送器は、図1に示した実施形態の2線式伝送器に受信機CPU106を接続して構成されている。また、図3では、伝送路N1に接続された外部電源Vccや抵抗素子107、基準伝送路N2に接続されるGND線を明示し、2線式伝送器が使用されている状態を表すものとする。2線式伝送器は、外部電源Vccから抵抗素子107、伝送路N1を介して出力信号V3にかかる電力の供給を受ける。
受信器CPU106は、2線式伝送器の出力信号V3を入力し、センサSによって検出された物理量の大きさや強度等を検出する構成である。図3の回路では、2線式伝送器の内部で電流源102以外のすべての電流源をまとめて電流源105と表現し、出力電流I3以外のすべての電流の総和をI4として示すものとする。
次に、実施形態2の2線式伝送器の動作を説明する。
実施形態2の2線式伝送器の出力信号V3は、抵抗素子107を介して外部電源Vccにプルアップされている。センサ信号V1が低下して出力電流I3が増加すると、実施形態2では、抵抗素子107における電圧降下が増加して出力信号V3の電圧が低下する。このため、実施形態2では、センサ信号V1の低下に応じて連続的に低下する出力信号V3を得ることができる。
一方、センサ信号V1が上昇して出力電流I3が減少すると、抵抗素子107における電圧降下が減少し、出力信号V3の電圧が上昇する。このため、実施形態2では、センサ信号V1の上昇に応じて連続的に上昇する出力信号V3を得ることができる。
したがって、実施形態2の2線式伝送器は、センサ信号V1を、センサ信号V1に比例する連続的なアナログ電圧信号V3に変換することができる。
また、受信機CPU106は、2線式伝送器からの出力信号V3を受信することにより、センサSによって検出された温度、磁気、圧力等に関する情報を得ることができる。
また、従来技術では出力信号Voutの電圧を基準電圧Vref以下にすることができないが、実施形態2の2線式伝送器ではそのような制約はない。実施形態2は、抵抗素子103及び抵抗素子104の値を変えることにより、出力信号V3の電圧を任意に得ることができる。
図4は、本発明の実施形態3の2線式伝送器を説明するための回路図である。なお、実施形態3では、図4中に示した構成のうち、図1に示した構成と同様の構成については同様の符号を付し、説明を一部略するものとする。
・構成
実施形態3の2線式伝送器は、図1に示した実施形態1の2線式伝送器に、A/D変換器401、デジタル演算器402、D/A変換器403を追加して構成されている。また、実施形態3の図4においても、2線式伝送器の内部で電流源102以外のすべての電流源をまとめて電流源105と表現し、出力電流I3以外のすべての電流の総和をI4として示すものとする。
センサ信号V1はA/D変換器401によってデジタル信号に変換される。変換後のデジタル信号は、デジタル演算器402によって演算処理された後、D/A変換器403によってアナログ信号V1’に変換される。このような実施形態3によれば、センサ信号V1を任意の特性のアナログ信号V1’に変換した後に、実施形態1と同様の処理をすることができる。
実施形態3は、例えば、センサ信号のオフセットや感度を補正した後、出力信号V3に変換する場合に有利である。
101 オペアンプ
102、105 電流源
103、104、107 抵抗素子
106 CPU受信機
401 A/D変換器
402 デジタル演算器
403 D/A変換器
Claims (11)
- 入力信号に基づくアナログ電圧信号を第1伝送路に出力する2線式伝送器であって、前記第1伝送路と第2伝送路との中間電位を生成する中間電位生成回路と、
前記入力信号と前記中間電位とが供給される増幅器と、
前記増幅器によって出力される制御信号に基づいて、前記第1伝送路から前記第2伝送路に流れる電流を生成する電流生成回路と、
を含むことを特徴とする2線式伝送器。 - 前記第1伝送路は、
第1抵抗素子を介して電源に接続されることを特徴とする請求項1に記載の2線式伝送器。 - 前記増幅器は、
入力された前記入力信号と前記中間電位とが等しくなるように、前記制御信号を出力することを特徴とする請求項1または2に記載の2線式伝送器。 - 前記中間電位信号生成回路は、
前記第1伝送路と前記第2伝送路との間に直列接続された第2抵抗素子と第3抵抗素子とを含み、前記第2抵抗素子と前記第3抵抗素子との間において前記中間電位を生成することを特徴とする請求項1から3のいずれか1項に記載の2線式伝送器。 - 前記電流生成回路は、前記中間電位に基づき、前記電流を生成する電流源を含むことを特徴とする請求項1から4のいずれか1項に記載の2線式伝送器。
- 前記アナログ電圧信号は、前記第1伝送路を介して前記増幅器に電力として供給されることを特徴とする請求項1から5のいずれか1項に記載の2線式伝送器。
- 前記第1伝送路に接続され、前記アナログ電圧信号を受信する受信機をさらに含むことを特徴とする請求項1から6のいずれか1項に記載の2線式伝送器。
- 前記入力信号がアナログ信号である場合、前記入力信号をデジタル信号に変換して加工する加工回路と、
前記加工回路によって加工されたデジタル信号を、アナログ信号に変換して前記増幅器に出力するデジタル・アナログ変換回路と、
をさらに含むことを特徴とする請求項1から7のいずれか1項に記載の2線式伝送器。 - 前記入力信号はセンサから出力されるセンサ信号であることを特徴とする請求項1から8のいずれか1項に記載の2線式伝送器。
- 前記センサ信号を出力するセンサをさらに含むことを特徴とする請求項1から9のいずれか1項に記載の2線式伝送器。
- 前記第1伝送路に接続される前記第1抵抗素子と、前記第1抵抗素子に接続される前記電源と、をさらに含むことを特徴とする請求項1から10のいずれか1項に記載の2線式伝送器。
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CN201080003441.7A CN102227757B (zh) | 2009-10-21 | 2010-10-15 | 两线式传送器 |
JP2011508751A JP4830058B2 (ja) | 2009-10-21 | 2010-10-15 | 2線式伝送器 |
EP10824640.6A EP2346011A4 (en) | 2009-10-21 | 2010-10-15 | BIFILAR TRANSMITTER |
US13/131,945 US8405534B2 (en) | 2009-10-21 | 2010-10-15 | Two-wire transmitter |
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JP2009-242722 | 2009-10-21 |
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PCT/JP2010/006136 WO2011048786A1 (ja) | 2009-10-21 | 2010-10-15 | 2線式伝送器 |
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US (1) | US8405534B2 (ja) |
EP (1) | EP2346011A4 (ja) |
JP (1) | JP4830058B2 (ja) |
CN (1) | CN102227757B (ja) |
WO (1) | WO2011048786A1 (ja) |
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US20140074303A1 (en) * | 2012-09-10 | 2014-03-13 | Kevin M. Haynes | Two-wire transmitter terminal power diagnostics |
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US5373226A (en) * | 1991-11-15 | 1994-12-13 | Nec Corporation | Constant voltage circuit formed of FETs and reference voltage generating circuit to be used therefor |
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WO2002073792A2 (en) * | 2001-03-09 | 2002-09-19 | Techtronic A/S | An electret condensor microphone preamplifier that is insensitive to leakage currents at the input |
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- 2010-10-15 CN CN201080003441.7A patent/CN102227757B/zh not_active Expired - Fee Related
- 2010-10-15 US US13/131,945 patent/US8405534B2/en not_active Expired - Fee Related
- 2010-10-15 EP EP10824640.6A patent/EP2346011A4/en not_active Withdrawn
- 2010-10-15 JP JP2011508751A patent/JP4830058B2/ja not_active Expired - Fee Related
- 2010-10-15 WO PCT/JP2010/006136 patent/WO2011048786A1/ja active Application Filing
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JPS5737279Y2 (ja) * | 1975-06-11 | 1982-08-17 | ||
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JP4830058B2 (ja) | 2011-12-07 |
CN102227757B (zh) | 2014-06-25 |
US20110234434A1 (en) | 2011-09-29 |
EP2346011A1 (en) | 2011-07-20 |
EP2346011A4 (en) | 2014-04-30 |
JPWO2011048786A1 (ja) | 2013-03-07 |
US8405534B2 (en) | 2013-03-26 |
CN102227757A (zh) | 2011-10-26 |
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