JPH0579699U - Disconnection detection circuit - Google Patents
Disconnection detection circuitInfo
- Publication number
- JPH0579699U JPH0579699U JP1590392U JP1590392U JPH0579699U JP H0579699 U JPH0579699 U JP H0579699U JP 1590392 U JP1590392 U JP 1590392U JP 1590392 U JP1590392 U JP 1590392U JP H0579699 U JPH0579699 U JP H0579699U
- Authority
- JP
- Japan
- Prior art keywords
- detection circuit
- disconnection detection
- filter
- operational amplifier
- disconnection
- 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.)
- Pending
Links
Landscapes
- Arrangements For Transmission Of Measured Signals (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
(57)【要約】
【目的】 断線検出用バイアス電圧の影響を除去した断
線検出回路を得る。
【構成】 断線検出用のバイアス電源を交流とし、増幅
用オペアンプの出力にフィルターと整流用ダイオードを
設ける。
(57) [Summary] [Purpose] To obtain a disconnection detection circuit in which the influence of the disconnection detection bias voltage is removed. [Structure] A bias power supply for detecting disconnection is an alternating current, and a filter and a rectifying diode are provided at the output of an amplifying operational amplifier.
Description
【０００１】[0001]
この考案は、変換精度に影響を与えることなく、補償導線の断線を検出する断 線検出回路に関するものである。 The present invention relates to a wire breakage detection circuit for detecting wire breakage of a compensation lead wire without affecting conversion accuracy.
【０００２】[0002]
図５は、例えば実開昭57−118496号公報に示された従来の断線検出回路を示す ブロック図であり、図において、１はＡ／Ｄコンバータ、４は増幅用オペアンプ 、５は熱電対、６は抵抗、11はコントローラ、12はアナログスイッチ、13は抵抗 、14は抵抗である。 FIG. 5 is a block diagram showing a conventional disconnection detection circuit disclosed in, for example, Japanese Utility Model Laid-Open No. 57-118496, in which 1 is an A / D converter, 4 is an amplifying operational amplifier, 5 is a thermocouple, 6 is a resistor, 11 is a controller, 12 is an analog switch, 13 is a resistor, and 14 is a resistor.
【０００３】 次に動作について説明する。熱電対５の起電力は増幅用オペアンプ４で増幅さ れ、Ａ／Ｄコンバータ１でデジタルデータに変換される。通常時は電源電圧Ｖｃ ｃを抵抗13、抵抗14で分圧した電圧Ｖｂがアナログスイッチ12と抵抗６を通して オペアンプ４の入力に印加されるが、熱電対５の補償導線の抵抗値は抵抗６の抵 抗値と比べてきわめて小さいため、Ｖｂは分圧されて小さくなる。熱電対５が断 線するとオペアンプ４の入力がＶｂになるため、Ｖｂの電圧を熱電対の起電力の 電圧より大きくすれば断線の検出ができる。 ところが、この方式の場合、通常時でもバイアス電圧Ｖｂのために誤差が発生 するため、コントローラ11はＡ／Ｄコンバータに変換指令を出すとともにアナロ グスイッチ12をＯＦＦ状態にしてバイアス電圧Ｖｂがオペアンプ４の入力に印加 されないようにした。Next, the operation will be described. The electromotive force of the thermocouple 5 is amplified by the amplifying operational amplifier 4 and converted into digital data by the A / D converter 1. Normally, the voltage Vb obtained by dividing the power supply voltage Vcc by the resistor 13 and the resistor 14 is applied to the input of the operational amplifier 4 through the analog switch 12 and the resistor 6, but the resistance value of the compensating lead wire of the thermocouple 5 is that of the resistor 6. Since it is extremely smaller than the resistance value, Vb is divided and becomes smaller. When the thermocouple 5 is broken, the input of the operational amplifier 4 becomes Vb. Therefore, if the voltage of Vb is made higher than the electromotive force of the thermocouple, the break can be detected. However, in the case of this method, an error occurs due to the bias voltage Vb even in the normal state, so the controller 11 issues a conversion command to the A / D converter and turns off the analog switch 12 to turn off the bias voltage Vb of the operational amplifier 4. It was not applied to the input.
【０００４】[0004]
従来の断線検出回路は以上のように構成されているので、Ａ／Ｄコンバータに より変換されたデジタルデータからは断線検出ができないため、Ａ／Ｄコンバー タの入力をモニターし、断線検出する回路を追加する必要があった。また、アナ ログスイッチのリーク電流のため誤差を小さくすることが困難であるとともに、 コントロール回路があるため装置が複雑になるという問題点があった。 Since the conventional disconnection detection circuit is configured as described above, it is not possible to detect the disconnection from the digital data converted by the A / D converter. Therefore, the circuit that detects the disconnection by monitoring the input of the A / D converter. Had to add. Further, there is a problem that it is difficult to reduce the error due to the leak current of the analog switch, and the control circuit makes the device complicated.
【０００５】 この考案は上記のような課題を解決するためになされたものであり、アナログ スイッチによる切換を行なわずに断線検出のためのバイアス電圧の影響を除去で きる断線検出回路を得ることを目的とする。The present invention has been made to solve the above problems, and it is an object of the present invention to obtain a disconnection detection circuit capable of removing the influence of the bias voltage for detecting the disconnection without switching by an analog switch. To aim.
【０００６】[0006]
この考案に係る断線検出回路は、バイアス電圧を交流とし、増幅用オペアンプ の出力に整流用ダイオードとフィルターを設けたものである。 The disconnection detection circuit according to the present invention uses a bias voltage as an alternating current, and is provided with a rectifying diode and a filter at the output of an amplifying operational amplifier.
【０００７】[0007]
この考案における断線検出回路はバイアス電圧を交流とし、増幅用オペアンプ の出力に整流用ダイオードとフィルターを設けているので、通常時のバイアス電 圧による誤差を除去するとともに断線を検出する。 Since the disconnection detection circuit in this invention uses a bias voltage as an alternating current and is provided with a rectifying diode and a filter at the output of the amplifying operational amplifier, it eliminates an error due to a bias voltage in a normal time and detects a disconnection.
【０００８】[0008]
実施例１． 以下、この考案の実施例１を図に基づいて説明する。 図１において１はＡ／Ｄコンバータ、２はフィルター、３はオペアンプ、４は オペアンプ、５は熱電対、６は抵抗、７は交流電源、８は抵抗、９はダイオード 、10はコンデンサである。 Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an A / D converter, 2 is a filter, 3 is an operational amplifier, 4 is an operational amplifier, 5 is a thermocouple, 6 is a resistor, 7 is an AC power supply, 8 is a resistor, 9 is a diode, and 10 is a capacitor.
【０００９】 次に、動作について説明する。図１において、通常時は交流電源７の電圧は抵 抗６、コンデンサ10を通してオペアンプ４の入力に印加されるが、熱電対５の補 償導線の抵抗値は抵抗６の抵抗値と比べて小さいため交流電源７の電圧は分圧は されて小さくなる。ゆえにフィルター２の入力は熱電対５の出力に小さな交流が 重畳され、図２に示すような波形になる。交流分はフィルター２でカットされる ため、Ａ／Ｄコンバータ１の入力は熱電対５の出力の直流分のみとなる。 熱電対５が断線するとオペアンプ４の入力は交流電源７の電圧になる。オペア ンプ３の入力はダイオード９があるため、負にならない。フィルター２の入力は 図３に示すような半波整流波形となり、フィルター２で交流分をカットしても直 流成分が残る。残った直流成分が熱電対５の信号を入力したときのフィルター２ の出力よりも大きくなるようにすれば断線の検出ができる。Next, the operation will be described. In FIG. 1, the voltage of the AC power supply 7 is normally applied to the input of the operational amplifier 4 through the resistor 6 and the capacitor 10, but the resistance value of the compensation wire of the thermocouple 5 is smaller than the resistance value of the resistor 6. Therefore, the voltage of the AC power supply 7 is divided and reduced. Therefore, the input of the filter 2 has a small alternating current superimposed on the output of the thermocouple 5 and has a waveform as shown in FIG. Since the AC component is cut by the filter 2, the input of the A / D converter 1 is only the DC component of the output of the thermocouple 5. When the thermocouple 5 is broken, the input of the operational amplifier 4 becomes the voltage of the AC power supply 7. The input of the operational amplifier 3 does not become negative because of the diode 9. The input of the filter 2 has a half-wave rectified waveform as shown in Fig. 3. Even if the AC component is cut by the filter 2, the direct current component remains. The disconnection can be detected by making the remaining DC component larger than the output of the filter 2 when the signal of the thermocouple 5 is input.
【００１０】 実施例２． なお、上記実施例１では、Ａ／Ｄコンバータ１の前段にフィルター２を設けて いるが、Ａ／Ｄコンバータ１を二重積分型とすることにより、実施例２を示す図 ４のように、Ａ／Ｄコンバータ１の前段のフィルター２を省略してもよい。Example 2. Although the filter 2 is provided in the preceding stage of the A / D converter 1 in the above-described first embodiment, the A / D converter 1 is of the double integration type, so that as shown in FIG. The filter 2 at the front stage of the A / D converter 1 may be omitted.
【００１１】[0011]
以上のように、この考案によれば、断線検出用のバイアス電源を交流とし、整 流用ダイオードとフィルターを設けたので通常時に断線検出用のバイアス電源の 影響がない、断線検出回路が得られる効果がある。 また実施例２によればＡ／Ｄコンバータ前段のフィルターを省略することがで きるのでコストが低減できるとともに装置を小型化することができる効果がある 。 As described above, according to the present invention, since the bias power supply for disconnection detection is AC and the rectifying diode and the filter are provided, the effect of the disconnection detection circuit can be obtained without the influence of the bias power supply for disconnection detection during normal operation. There is. Further, according to the second embodiment, the filter in the preceding stage of the A / D converter can be omitted, so that there is an effect that the cost can be reduced and the device can be downsized.
【図１】この考案の実施例１による断線検出回路の回路
図である。FIG. 1 is a circuit diagram of a disconnection detection circuit according to a first embodiment of the present invention.
【図２】この考案の実施例１による断線検出回路の通常
時のフィルター入力波形図である。FIG. 2 is a filter input waveform diagram in a normal state of the disconnection detection circuit according to the first embodiment of the present invention.
【図３】この考案の実施例１による断線検出回路の断線
検出時のフィルター入力波形図である。FIG. 3 is a filter input waveform diagram when a disconnection is detected by the disconnection detection circuit according to the first embodiment of the present invention.
【図４】この考案の実施例２による断線検出回路の回路
図である。FIG. 4 is a circuit diagram of a disconnection detection circuit according to a second embodiment of the present invention.
【図５】従来の断線検出回路の回路図である。FIG. 5 is a circuit diagram of a conventional disconnection detection circuit.
１ Ａ／Ｄコンバータ ２ フィルター ３ オペアンプ ４ オペアンプ ５ 熱電対 ６ 抵抗 ７ 交流電源 ８ 抵抗 ９ ダイオード 10 コンデンサ 1 A / D converter 2 Filter 3 Operational amplifier 4 Operational amplifier 5 Thermocouple 6 Resistance 7 AC power supply 8 Resistance 9 Diode 10 Capacitor
Claims (1)
ンプの入力が負にならないようにする整流用ダイオード
と、フィルターとを備えた断線検出回路。1. A disconnection detection circuit comprising an AC power supply for detecting disconnection, a rectifying diode for preventing an input of an amplifying operational amplifier from becoming negative, and a filter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1590392U JPH0579699U (en) | 1992-03-26 | 1992-03-26 | Disconnection detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1590392U JPH0579699U (en) | 1992-03-26 | 1992-03-26 | Disconnection detection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0579699U true JPH0579699U (en) | 1993-10-29 |
Family
ID=11901739
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1590392U Pending JPH0579699U (en) | 1992-03-26 | 1992-03-26 | Disconnection detection circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0579699U (en) |
-
1992
- 1992-03-26 JP JP1590392U patent/JPH0579699U/en active Pending
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