JPH0468918A - Isolation type contact signal detecting circuit - Google Patents
Isolation type contact signal detecting circuitInfo
- Publication number
- JPH0468918A JPH0468918A JP18023290A JP18023290A JPH0468918A JP H0468918 A JPH0468918 A JP H0468918A JP 18023290 A JP18023290 A JP 18023290A JP 18023290 A JP18023290 A JP 18023290A JP H0468918 A JPH0468918 A JP H0468918A
- Authority
- JP
- Japan
- Prior art keywords
- photocoupler
- resistor
- contact
- voltage
- zener diode
- 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
- 238000002955 isolation Methods 0.000 title 1
- 238000001514 detection method Methods 0.000 claims abstract description 19
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
Landscapes
- Electronic Switches (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、接点信号を検出する回路、特にフォトカプラ
により内部回路と接点信号を電気的に絶縁した検出回路
に関するものでる。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit for detecting a contact signal, and particularly to a detection circuit in which an internal circuit and a contact signal are electrically isolated by a photocoupler.
［従来の技術］
プロセスコンピュータやシーケンサ等の装置において、
スイッチ接点やリレー接点の信号を検出、入力する場合
、フォトカプラにより内部制御回路と接点信号を電気的
に絶縁するのが一般的ある。[Prior art] In devices such as process computers and sequencers,
When detecting and inputting signals from switch contacts or relay contacts, it is common to use a photocoupler to electrically isolate the internal control circuit and the contact signals.
第２図はフォトカプラにより内部制御回路と接点信号を
電気的に絶縁するようにした従来の検出回路図であり、
以下に接点信号検出時の動作を説明する。Figure 2 is a conventional detection circuit diagram in which the internal control circuit and contact signals are electrically isolated using a photocoupler.
The operation at the time of contact signal detection will be explained below.
被検出接点２が閉じると、検出用直１電源３により電流
−１限抵抗４ａを通じてフォトカプラ１のアノード１ａ
とカソード１ｂとの間に電流が流れる。アノード１ａ、
カソード１ｂ間には保護ダイオードが挿入されており、
逆電圧が印加されたときのフォトカプラ破損を防止して
いる。フォトカプラ１の内部では、アノードＩａ、カソ
ード１ｂ間に流れる電流を、電気的に絶縁した状態で出
力側のコレクタ１Ｃ、エミツタ１ｄ間に増倍して伝達す
る。そうするとプルアップされたコレクタ１Ｃと接地さ
れたエミッタ１ｄとの間に電流が流れ、Ａ点の電位が下
がる。この変化をコンパレータ６で電位子ｖｒｅｒとの
比較によりにＷ１滅し、内部制御回路は接点“閉”の信
号として処理を行う。When the contact 2 to be detected is closed, the anode 1a of the photocoupler 1 is supplied to the anode 1a of the photocoupler 1 through the current-1 limiting resistor 4a by the direct 1 power supply 3 for detection.
A current flows between the cathode 1b and the cathode 1b. anode 1a,
A protection diode is inserted between the cathode 1b,
This prevents damage to the photocoupler when reverse voltage is applied. Inside the photocoupler 1, the current flowing between the anode Ia and the cathode 1b is multiplied and transmitted between the output side collector 1C and emitter 1d in an electrically insulated state. Then, a current flows between the pulled-up collector 1C and the grounded emitter 1d, and the potential at point A decreases. This change is compared with the potential vrer by the comparator 6 and W1 is eliminated, and the internal control circuit processes it as a contact "closed" signal.
［発明が解決しようとする課題］
ところで、絶縁形接点信号検出回路はフォトカプラ素子
の′Ｎ流伝達特性（電流伝達比）を用いた回路であるが
、電流伝達比の非常に大きなフォトカプラが使われた場
合、接点“開”とＷｔ識されるべき絶縁抵抗値において
、フォトカプラの入力端子間に流れる微小な電流が増倍
されてフォトカプラの出力端子間に伝達され、誤って接
点“閉”と内部制御回路にｌ！！識されることがある。[Problems to be Solved by the Invention] Incidentally, the insulated contact signal detection circuit is a circuit that uses the 'N current transfer characteristic (current transfer ratio) of a photocoupler element, but it is difficult to use a photocoupler with a very large current transfer ratio. When used, the minute current flowing between the input terminals of the photocoupler is multiplied and transmitted between the output terminals of the photocoupler at an insulation resistance value that should be recognized as the contact "open", and the contact is mistakenly opened. Closed” and the internal control circuit is closed! ! may be recognized.
一方、フォトカプラの電流伝達比は素子毎にバラツキが
あり、値の小さなフォトカプラのみを製造するのは因数
である。On the other hand, the current transfer ratio of photocouplers varies from element to element, which is a factor in manufacturing only photocouplers with small values.
このように、上記した従来技術は接点信号のノイズマー
ジンを有し、かつ、−度変化や経年変化を考處すると、
電流伝達比のそろったフォトカプラを選別しなければな
らないという問題点があった。In this way, the above-mentioned conventional technology has a noise margin for the contact signal, and when considering -degree change and secular change,
There was a problem in that photocouplers with the same current transfer ratio had to be selected.
本発明の目的は、前記した従来技術の問題点を解消し、
フォトカプラの電流伝達比のバラツキがあっても誤動作
しない絶縁形接点信号検出口路を提供することにある。The purpose of the present invention is to solve the problems of the prior art described above,
An object of the present invention is to provide an insulated contact signal detection path that does not malfunction even if there are variations in the current transfer ratio of a photocoupler.
［課題を解決するための手段及び作用］上記目的を達成
するため、本発明においては、フォトカプラの入力端子
にツェナーダイオードを直列に接続し、かつ、接続した
画素子に対して、抵抗を並列に接続しており、それによ
って接点“ｍ”″を検出するしきい値を＾くするととも
に、フォトカプラの電流伝達比のバラツキに依存しない
安定したしきい値が得られるようにしたものである。[Means and effects for solving the problem] In order to achieve the above object, in the present invention, a Zener diode is connected in series to the input terminal of a photocoupler, and a resistor is connected in parallel to the connected pixel element. This makes it possible to reduce the threshold value for detecting the contact "m" and to obtain a stable threshold value that does not depend on variations in the current transfer ratio of the photocoupler. .
［実施例］ 以上、本発明の一実施例を第１図により説明する。[Example] An embodiment of the present invention will be described above with reference to FIG.
フォトカプラ１の出力端子１ｃ、ｌｄ以降において、Ａ
点の信号レベル変化をコンパレータ６にて認識し、内部
１１Ｊ御回路に取り込む部分は従来例の第２図と同じで
あるが、被検出接点２“閉”によりフォトカプラ１のア
ノードｌａ、カソード１ｄ間に電流を流しフォトカプラ
を動作させる部分において大きく相違している。After the output terminals 1c and ld of the photocoupler 1, A
The part where the signal level change at the point is recognized by the comparator 6 and taken into the internal control circuit 11J is the same as the conventional example shown in FIG. There is a major difference in the part where current is passed between them to operate the photocoupler.
その第１点はフォトカプラ１の入力端にツェナーダイオ
ード８を直列に接続していることである。The first point is that a Zener diode 8 is connected in series to the input end of the photocoupler 1.
ダイオード９はフォトカプラ１の入力端に逆電流が流れ
るのを防止するために接続されている。Diode 9 is connected to the input terminal of photocoupler 1 to prevent reverse current from flowing.
第２点はこれらの素子に対して抵抗４ｂを並列に接続し
ている点である。この並列抵抗４ｂにより接点“閉”を
検出するしきい値を上げることができる。その理由を以
下に説明する。The second point is that a resistor 4b is connected in parallel to these elements. This parallel resistor 4b can increase the threshold value for detecting the "closed" contact. The reason for this will be explained below.
接点検出端７ａ、７ｂに抵抗値ｒの抵抗を接続すると、
直［２源３により、その抵抗には電流が流れる。従来例
の第２図の回路においては、その電流がそのままフォト
カプラ１の入力端に流れるため、接点閉”の検出におけ
るしきい値がフォトカプラ１のＮ流伝達比に依存してい
た。しかし、本発明の第１図の回路においては、抵抗［
１ｒと並列抵抗４ｂとの分圧によって８０間に電位差を
生じる。この電位差がツェナーダイオード８のツェナー
電圧値より大きくなった場合に始めてフォトカプラの入
力端に電流が流れるようにしているため、検出端７ａ、
７ｂに接続した抵抗値ｒを接点“閉”として検出したい
場合は、８０間の電位差よりもツェナーダイオード８の
ツェナー電圧値を小さく選べばよい。逆に、抵抗ｉ１ｒ
を接点“閉″とじて検出したくない場合には、８０間の
電位差よりもツェナーダイオード８のツェナー電圧値を
大きく選べばよいことになる。このようにして抵抗４ｂ
及びツェナーダイオード８のツェナー電圧値により、接
点“閉”検出のしきい値を土げることができる。そして
、このしきい値を超えた場合にフォトカプラの電流伝達
比の最小値で設計しておけば、確実に接点閉”を検出す
るため、安定した動作を得ることができる。When a resistor with a resistance value r is connected to the contact detection terminals 7a and 7b,
A current flows through the resistor due to the direct current source 3. In the conventional circuit shown in FIG. 2, the current flows directly to the input terminal of the photocoupler 1, so the threshold value for detecting contact closure depends on the N-current transfer ratio of the photocoupler 1. , in the circuit of FIG. 1 of the present invention, the resistor [
A potential difference is generated between 80 and 1r by the voltage division between 1r and parallel resistor 4b. Since current flows to the input terminal of the photocoupler only when this potential difference becomes larger than the Zener voltage value of the Zener diode 8, the detection terminal 7a,
If it is desired to detect the resistance value r connected to the terminal 7b as a "closed" contact, the Zener voltage value of the Zener diode 8 may be selected to be smaller than the potential difference between the terminals 80 and 80. On the contrary, the resistance i1r
If you do not want to detect the contact "closed", you can choose the Zener voltage value of the Zener diode 8 to be larger than the potential difference between 80 and 80. In this way, resistor 4b
According to the Zener voltage value of the Zener diode 8, the threshold value for contact "closed" detection can be lowered. If the photocoupler is designed with the minimum value of the current transfer ratio when this threshold value is exceeded, stable operation can be achieved because contact closure is reliably detected.
［発明の効果１
本発明は、以上説明したように構成されているので、次
に記載されるような効果を奏する。[Effect 1 of the Invention Since the present invention is configured as described above, it produces the following effects.
（１）電流伝達比の小さなフォトカプラを選別する必要
がないため、回路製作時の経済性を向上できる。(1) Since there is no need to select photocouplers with a small current transfer ratio, economical efficiency during circuit production can be improved.
（２）フォトカプラのバラツキに依存しない安定した接
点閉”検出のしきい値を設定できるため、接点信号検出
における信頼性を向上できる。(2) Since it is possible to set a stable contact closure detection threshold that is independent of photocoupler variations, reliability in contact signal detection can be improved.
第１図は本発明の一実施例に係る絶縁形接点信号検出回
路を示す回路図、第２図は従来の絶縁形接点信号検出回
路を示す回路図である。
１：フォトカプラ、
１ａニアノード、
１ｂ：カソード、
１Ｃ：コレクタ、
１ｄ：エミッタ、
２：被検出接点、
３：検出用直流電源、
４ａ、４ｂ＝抵抗、
５：保護ダイオード、
６：コンパレータ、
７ａ、７ｂ：接点検出端、
８：ツェナーダイオード、
９：逆電流防止用ダイオード。FIG. 1 is a circuit diagram showing an insulated contact signal detection circuit according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a conventional insulated contact signal detection circuit. 1: Photocoupler, 1a near node, 1b: cathode, 1C: collector, 1d: emitter, 2: detected contact, 3: detection DC power supply, 4a, 4b = resistor, 5: protection diode, 6: comparator, 7a, 7b: Contact detection end, 8: Zener diode, 9: Reverse current prevention diode.
Claims (1)
施して接点信号を検出するようにした絶縁形接点信号検
出回路において、フォトカプラの入力端子にツェナーダ
イオードを直列に接続し、かつ、フォトカプラ及びツェ
ナーダイオードに対して抵抗を並列に接続したことを特
徴とする絶縁形接点信号検出回路。1. In an isolated contact signal detection circuit that detects contact signals by electrically insulating the internal control circuit with a photocoupler, a Zener diode is connected in series to the input terminal of the photocoupler, and the photocoupler and An isolated contact signal detection circuit characterized by connecting a resistor in parallel to a Zener diode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18023290A JPH0468918A (en) | 1990-07-06 | 1990-07-06 | Isolation type contact signal detecting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18023290A JPH0468918A (en) | 1990-07-06 | 1990-07-06 | Isolation type contact signal detecting circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0468918A true JPH0468918A (en) | 1992-03-04 |
Family
ID=16079688
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18023290A Pending JPH0468918A (en) | 1990-07-06 | 1990-07-06 | Isolation type contact signal detecting circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0468918A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3399616A1 (en) * | 2017-05-05 | 2018-11-07 | Hamilton Sundstrand Corporation | Ground/voltage open input |
| US11084050B2 (en) | 2017-04-03 | 2021-08-10 | Delavan Inc. | Pulsed spraybar injector |
-
1990
- 1990-07-06 JP JP18023290A patent/JPH0468918A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11084050B2 (en) | 2017-04-03 | 2021-08-10 | Delavan Inc. | Pulsed spraybar injector |
| US11738356B2 (en) | 2017-04-03 | 2023-08-29 | Collins Engine Nozzles, Inc. | Pulsed spraybar injector |
| EP3399616A1 (en) * | 2017-05-05 | 2018-11-07 | Hamilton Sundstrand Corporation | Ground/voltage open input |
| US10476256B2 (en) | 2017-05-05 | 2019-11-12 | Hamilton Sundstrand Corporation | Ground/voltage open input |
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