JP2876689B2 - Proximity switch - Google Patents
Proximity switchInfo
- Publication number
- JP2876689B2 JP2876689B2 JP2059254A JP5925490A JP2876689B2 JP 2876689 B2 JP2876689 B2 JP 2876689B2 JP 2059254 A JP2059254 A JP 2059254A JP 5925490 A JP5925490 A JP 5925490A JP 2876689 B2 JP2876689 B2 JP 2876689B2
- Authority
- JP
- Japan
- Prior art keywords
- oscillation
- amplitude
- comparator
- circuit
- oscillation circuit
- 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 - Fee Related
Links
Description
本願発明は、被検出物体が所定位置に接近したことを
検出する近接スイッチに関する。The present invention relates to a proximity switch for detecting that an object to be detected approaches a predetermined position.
従来の近接スイッチの一例を第４図に示す。ここで近
接スイッチは、検出コイル１を有する発振回路２と、こ
の発振回路２の出力電圧を整流する整流回路３と、抵抗
４と、コンデンサ５からなる平滑回路と、この平滑回路
の出力すなわち発振回路２の出力を弁別するコンパレー
タ６と、出力トランジスタ７から構成されている。 被検出体が検出コイル１に接近すると、第５図に示す
ように発振回路の出力（ａ）の振幅は減衰する。 この出力（ａ）が整流回路３により整流され、抵抗４
と平滑コンデンサ５により平滑化されて直流電圧（ｂ）
となり、コンパレータ６により所定の電圧で弁別されて
検出信号（ｃ）を得、この検出信号（ｃ）でトランジス
タ７をON・OFFし外部出力が得られ、この外部出力によ
り被検出体が接近したことを検出する。FIG. 4 shows an example of a conventional proximity switch. Here, the proximity switch includes an oscillation circuit 2 having a detection coil 1, a rectification circuit 3 for rectifying an output voltage of the oscillation circuit 2, a smoothing circuit including a resistor 4 and a capacitor 5, and an output of the smoothing circuit, that is, an oscillation. It comprises a comparator 6 for discriminating the output of the circuit 2 and an output transistor 7. When the detected object approaches the detection coil 1, the amplitude of the output (a) of the oscillation circuit is attenuated as shown in FIG. This output (a) is rectified by the rectifier circuit 3 and
And DC voltage (b) smoothed by the smoothing capacitor 5
The detection signal (c) is obtained by being discriminated by the comparator 6 at a predetermined voltage, and the transistor 7 is turned ON / OFF by the detection signal (c) to obtain an external output. Detect that.
従来の近接スイッチは平滑コンデンサの容量を発振回
路の発振周波数により変える必要があり、かつ容量が大
きいから集積回路としてまとめることができず、スイッ
チの小形化に限界があった。 本発明の目的は、平滑コンデンサを除去し、小形化し
た近接スイッチを提供することにある。In the conventional proximity switch, it is necessary to change the capacity of the smoothing capacitor according to the oscillation frequency of the oscillation circuit, and since the capacity is large, it cannot be integrated as an integrated circuit, and there is a limit to downsizing of the switch. It is an object of the present invention to provide a miniaturized proximity switch by eliminating a smoothing capacitor.
前述した課題を解決するために本発明によれば、検出
コイルを有し、被検出体の接近により発振振幅の減衰時
発振が完全に停止しないようにした発振回路と、この発
振回路の発振振幅を整流平滑などの処理をすることな
く、発振回路が取りうる最低の振幅よりも高く、かつ、
発振回路が取りうる最大の振幅よりも低く設定された所
定の基準レベルと比較し、発振振幅がこの基準レベルを
越えている間発振周波数に同期したパルス信号を発生す
る第１のコンパレータと、前記発振回路の発振振幅を整
流平滑などの処理をすることなく、発振回路が取りうる
最低の振幅よりも低い所定の基準レベルと比較し、発振
回路の振幅に係わらず発振周波数に同期したパルス信号
を発生する第２のコンパレータと、前記第２のコンパレ
ータのパルス信号が発せられている間において、第１の
コンパレータのパルス信号の発信の有無の状態を計数
し、所定の回数連続して続いたときに被検出体の近接状
態の信号を発するディジタル検出回路と、を備えること
により達成される。According to the present invention, there is provided an oscillation circuit having a detection coil, wherein the oscillation does not completely stop when the oscillation amplitude is attenuated due to the approach of an object to be detected, and an oscillation amplitude of the oscillation circuit. Is higher than the minimum amplitude that the oscillation circuit can take without performing processing such as rectifying and smoothing, and
A first comparator for comparing with a predetermined reference level set lower than the maximum amplitude that can be taken by the oscillation circuit and generating a pulse signal synchronized with the oscillation frequency while the oscillation amplitude exceeds the reference level; Without performing processing such as rectifying and smoothing the oscillation amplitude of the oscillation circuit, the oscillation amplitude is compared with a predetermined reference level lower than the minimum amplitude that the oscillation circuit can take, and a pulse signal synchronized with the oscillation frequency regardless of the oscillation circuit amplitude is output. While the generated second comparator and the pulse signal of the second comparator are being emitted, the state of the presence / absence of the transmission of the pulse signal of the first comparator is counted. And a digital detection circuit that emits a signal indicating the proximity of the object to be detected.
本願発明では、最小の発振振幅に応答して第２のコン
パレータにより発生したクロックパルスの１パルス毎に
発振振幅の所定レベルで弁別する第１のコンパレータの
発生したパルスの有無をディジタル検出回路のシフトレ
ジスタに記憶させ、このパルスが所定数連続したとき検
出信号を発するようにして整流回路を省く。According to the present invention, the digital detector shifts the presence or absence of a pulse generated by the first comparator which discriminates at a predetermined level of the oscillation amplitude for each pulse of the clock pulse generated by the second comparator in response to the minimum oscillation amplitude. The rectifier circuit is stored in a register, and a detection signal is generated when a predetermined number of consecutive pulses are generated.
第１図ないし第３図は本願発明による近接スイッチの
実施例を示し、第４図と同一のものには第４図と同一の
符号を付している。第１図において、近接スイッチは検
出コイル１を有する発振回路２、２つのコンパレータ
６、８、ディジタル検出回路10を主要素とし、発振回路
２は第２図に示すように発振振幅ａが常時は振幅a1と大
きいが、被検出体が検出コイル１に接近したとき次第に
減衰する。 しかし最も減衰しても振幅a2を維持するようにされた
公知の回路である。第２コンパレータ８は最小の発振振
幅に応答してパルスP1を発生する。また、ディジタル検
出回路10は、パルスP1毎にパルスP2を計数し、このパル
スP2が所定数連続したとき信号を発する。そして発振回
路２の出力端は、両コンパレータ６、８のそれぞれの入
力端に接続され、この両コンパレータ６、８のそれぞれ
の出力端は、ANDゲート11の別個の入力端に接続されて
いる。 このANDゲート11の出力端は、次に述べるディジタル
検出回路10を構成するフリップフロップ（以下FFと略称
する）12のセット端Ｓに接続されている。また、コンパ
レータ８の出力端は、コンデンサ13を介してFF12のリセ
ット端Ｒに接続されている。ディジタル検出回路10はFF
12、４個のFF14〜FF17からなるシフトレジスタ、２つの
ANDゲート18、19およびFF20からなり、FF12の出力端Ｑ
がFF14の入力端Ｄに接続され、FF14〜FF17は順次出力端
Ｑが次のFFの入力端Ｄに接続されシフトレジスタが構成
されている。ANDゲート18はFF14〜FF17の出力端Ｑがそ
の入力端に接続され、その出力端はFF20のリセット入力
端Ｒに接続されている。また、ANDゲート19はFF14〜FF1
7の各反転出力端がその入力端に接続され、その出力端
はF20のセット入力端Ｓに接続されている。 以下第３図に示すタイムチャートを参照しながらこの
近接スイッチの動作を説明する。検出コイル１に被検出
体が接近すると、振幅ａが減衰する。 コンパレータ８は、発振回路が取りうる最低の振幅よ
りも低い所定の基準レベルl1と比較し、発振回路の振幅
に係わらず発振周波数に同期したパルス信号を発生する
から出力P1に示すように振幅ａの大小にかかわらず半波
毎に１パルスを発生する。 コンパレータ６は、発振回路が取りうる最低の振幅よ
りも高く、かつ発振回路が取りうる最大の振幅よりも低
く設定された所定のレベルl2で弁別するから出力P2に示
すように被検出体が接近しないときはパルスを発生する
が被検出体が接近するとパルスを発生せずにローレベル
（以下“L"と略称する）に転ずる。コンパレータ８の出
力P1がハイレベル（これを“H"と略称する）のとき、AN
Dゲート11が受付状態となり、この間にコンパレータ６
にパルス出力P2が発生するとFF12がセットされる。コン
パレータ８の出力P1が“L"に変わるとき、コンデンサ13
を介してFF12のリセット端子Ｒに入力が与えられFF12は
リセットされる。したがって、FF12の出力P3は被検出体
が接近しないときはパルスになるが、接近したときは
“L"になり、パルスを発生しない。コンパレータ８の出
力は、各FF14〜FF17のクロック入力にもなっているの
で、コンパレータ８の出力P1が“H"に変化するときFF1
2、FF14〜FF17の出力は次段へとシフトされる。すなわ
ち、４回同じデータが連続し、例えば、FF14〜FF17の反
転出力端の出力P4〜P7がすべて“H"に転じると、ANDゲ
ート18は条件が揃ってFF20はセットされ、FF20の出力端
Ｑから検出出力P8が得られ、この外部への検出出力P8に
より被検出体が接近したことを検出することができる。 なお、FF14〜FF17の出力端Ｑの出力が全て“H"になっ
たときANDゲート18によりFF20はリセットされる。1 to 3 show an embodiment of a proximity switch according to the present invention. The same components as those in FIG. 4 are denoted by the same reference numerals as in FIG. In FIG. 1, the proximity switch has an oscillating circuit 2 having a detecting coil 1, two comparators 6, 8 and a digital detecting circuit 10 as main elements, and the oscillating circuit 2 always has an oscillation amplitude a as shown in FIG. Although large amplitude a 1, gradually attenuated when the detection object approaches the detection coil 1. However, even the most attenuated a known circuit which is adapted to maintain the amplitude a 2. The second comparator 8 generates a pulse P 1 in response to the minimum oscillation amplitude. The digital detecting circuit 10 counts the pulse P 2 for each pulse P 1, emits a signal when the pulse P 2 are continuous predetermined number. The output terminal of the oscillation circuit 2 is connected to the respective input terminals of the comparators 6 and 8, and the respective output terminals of the comparators 6 and 8 are connected to separate input terminals of the AND gate 11. An output terminal of the AND gate 11 is connected to a set terminal S of a flip-flop (hereinafter abbreviated as FF) 12 constituting the digital detection circuit 10 described below. The output terminal of the comparator 8 is connected to the reset terminal R of the FF 12 via the capacitor 13. Digital detection circuit 10 is FF
12, four shift registers consisting of FF14 to FF17, two shift registers
Consists of AND gates 18, 19 and FF20, the output Q of FF12
Are connected to the input terminal D of the FF14, and the output terminals Q of the FF14 to FF17 are sequentially connected to the input terminal D of the next FF to form a shift register. The output terminal Q of the FF14 to FF17 is connected to the input terminal of the AND gate 18, and the output terminal is connected to the reset input terminal R of the FF20. Also, AND gate 19 is FF14 to FF1
Each of the inverted output terminals 7 is connected to its input terminal, and its output terminal is connected to the set input terminal S of F20. Hereinafter, the operation of the proximity switch will be described with reference to a time chart shown in FIG. When an object to be detected approaches the detection coil 1, the amplitude a is attenuated. Comparator 8 compares the predetermined and reference level l 1 less than the lowest amplitude oscillation circuit can take, as shown in the output P 1 from generating a pulse signal synchronized with the oscillation frequency irrespective of the amplitude of the oscillation circuit One pulse is generated for each half wave regardless of the magnitude of the amplitude a. The comparator 6 is higher than the lowest amplitude oscillation circuit may take, and the oscillation circuit is the largest object to be detected as shown in the output P 2 from discriminating a predetermined level l 2 which is set lower than the amplitude that can be taken When the object does not approach, a pulse is generated, but when the object to be detected approaches, no pulse is generated, and the level changes to a low level (hereinafter abbreviated as “L”). When the output P 1 of the comparator 8 is at a high level (this is abbreviated as “H”),
The D gate 11 enters the receiving state, during which the comparator 6
When the pulse output P 2 is generated FF12 is set to. When the output P 1 of the comparator 8 changes to “L”, the capacitor 13
Is input to the reset terminal R of the FF12 via the FF12, and the FF12 is reset. Therefore, the output P 3 of FF12 is becomes a pulse when the object to be detected does not close when approaching goes to "L", the not generate a pulse. The output of the comparator 8, so that is also the clock input of each FF14～FF17, when the output P 1 of the comparator 8 is changed to "H" FF1
2. The outputs of FF14 to FF17 are shifted to the next stage. That is, 4 times the same data is continuously, for example, when the output P 4 to P 7 of the inverted output terminal of FF14~FF17 turns to all "H", the AND gate 18 is FF20 aligned condition is set, the FF20 A detection output P8 is obtained from the output terminal Q, and the detection output P8 to the outside can detect that the detected object approaches. The FF20 is reset by the AND gate 18 when the outputs of the output terminals Q of the FF14 to FF17 all become "H".
以上説明したように、本願発明によれば、平滑コンデ
ンサを必要とせず、集積回路だけで構成でき、小形にす
ることができる。さらに、コンデンサの容量の誤差の影
響が除かれ、安定した検出ができる。As described above, according to the present invention, a smoothing capacitor is not required, it can be constituted only by an integrated circuit, and the size can be reduced. Further, the influence of the error of the capacitance of the capacitor is eliminated, and stable detection can be performed.
第１図ないし第３図は、本願発明による近接スイッチの
実施例を示し、第１図は結線図、第２図は発振回路の出
力図、第４図および第５図は従来の近接スイッチの一例
を示し、第４図は結線図、第５図は動作を示すタイムチ
ャートである。1 to 3 show an embodiment of a proximity switch according to the present invention. FIG. 1 is a connection diagram, FIG. 2 is an output diagram of an oscillation circuit, and FIGS. 4 and 5 are diagrams of a conventional proximity switch. FIG. 4 is a connection diagram, and FIG. 5 is a time chart showing the operation.
1:検出コイル、2:発振回路、６、8:コンパレータ、10:
ディジタル検出回路。1: detection coil, 2: oscillation circuit, 6, 8: comparator, 10:
Digital detection circuit.
Claims (1)
発振振幅の減衰時発振が完全に停止しないようにした発
振回路と、 この発振回路の発振振幅を整流平滑などの処理をするこ
となく、発振回路が取りうる最低の振幅よりも高く、か
つ、発振回路が取りうる最大の振幅よりも低く設定され
た所定の基準レベルと比較し、発振振幅がこの基準レベ
ルを越えている間発振周波数に同期したパルス信号を発
生する第１のコンパレータと、 前記発振回路の発振振幅を整流平滑などの処理をするこ
となく、発振回路が取りうる最低の振幅よりも低い所定
の基準レベルと比較し、発振回路の振幅に係わらず発振
周波数に同期したパルス信号を発生する第２のコンパレ
ータと、 前記第２のコンパレータのパルス信号が発せられている
間において、第１のコンパレータのパルス信号の発信の
有無の状態を計数し、所定の回数連続して続いたときに
被検出体の近接状態の信号を発するディジタル検出回路
と、 を備えていることを特徴とする近接スイッチ。An oscillation circuit having a detection coil so that oscillation does not completely stop when the oscillation amplitude is attenuated due to the approach of a detection object, and a process for rectifying and smoothing the oscillation amplitude of the oscillation circuit. The oscillation amplitude is compared with a predetermined reference level that is higher than the minimum amplitude that the oscillation circuit can take and that is lower than the maximum amplitude that the oscillation circuit can take. A first comparator for generating a pulse signal synchronized with the frequency, and comparing the oscillation amplitude of the oscillation circuit with a predetermined reference level lower than the minimum amplitude that the oscillation circuit can take without performing a process such as rectification and smoothing. A second comparator for generating a pulse signal synchronized with the oscillation frequency irrespective of the amplitude of the oscillation circuit, and a first comparator for generating a pulse signal of the second comparator while the pulse signal is being generated. A digital detection circuit that counts the state of the presence or absence of the transmission of the pulse signal of the comparator and that emits a signal of the proximity state of the detection object when the detection signal continues for a predetermined number of times. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2059254A JP2876689B2 (en) | 1990-03-09 | 1990-03-09 | Proximity switch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2059254A JP2876689B2 (en) | 1990-03-09 | 1990-03-09 | Proximity switch |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03261221A JPH03261221A (en) | 1991-11-21 |
| JP2876689B2 true JP2876689B2 (en) | 1999-03-31 |
Family
ID=13108064
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2059254A Expired - Fee Related JP2876689B2 (en) | 1990-03-09 | 1990-03-09 | Proximity switch |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2876689B2 (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5239355A (en) * | 1975-09-23 | 1977-03-26 | Omron Tateisi Electronics Co | Switching circuit |
| JPS5968130A (en) * | 1982-10-09 | 1984-04-18 | 竹中電子工業株式会社 | Photoelectric switch |
| JPS62117413A (en) * | 1985-11-15 | 1987-05-28 | Omron Tateisi Electronics Co | High frequency oscillating type contactless switch |
-
1990
- 1990-03-09 JP JP2059254A patent/JP2876689B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03261221A (en) | 1991-11-21 |
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