JP2004120552A

JP2004120552A - Multiaxial photoelectric switch

Info

Publication number: JP2004120552A
Application number: JP2002283310A
Authority: JP
Inventors: Jun Ito; 伊藤　純
Original assignee: Sunx Ltd
Current assignee: Panasonic Industrial Devices SUNX Co Ltd
Priority date: 2002-09-27
Filing date: 2002-09-27
Publication date: 2004-04-15

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the speed of response from becoming slow even when detecting whether or not a smaller object is present to detect. <P>SOLUTION: In a multiaxial photoelectric switch 11, light projection elements 12a to 12e sequentially project light according to the order of a light projection element 12a, a light projection element 12c, a light projection element 12e, a light projection element 12b and a light projection element 12d. Whether a small object is present or not is detected by decreasing the arrangement pitch of the light projection elements 12a to 12e in a projector 12 and the arrangement pitch of photodetectors 13a to 13e of a light receiver 13. The speed of response can be prevented from becoming slow because there is no need to set the operation intervals of light projection operations of the light projection elements 12a to 12e large. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、投光器に略一列に配置された複数の投光手段と、複数の投光手段に１対１に対応するように受光器に略一列に配置された複数の受光手段とを備え、複数の受光手段の各々から出力されて増幅された受光信号の受光量に応じた信号レベルを複数の投光手段の各々の投光動作に同期させて閾値と比較して被検出対象物が存在しているか否かを検出する多光軸光電スイッチに関する。
【０００２】
【従来の技術】
従来の多光軸光電スイッチは、投光器に略一列に配置されて各々が投光動作を順次行う複数の投光素子と、複数の投光素子に１対１に対応するように受光器に略一列に配置されて各々が受光信号を出力する複数の受光素子と、複数の受光素子の各々から出力された受光信号を増幅する増幅回路と、複数の受光素子の各々から出力されて増幅回路により増幅された受光信号の受光量に応じた信号レベルを複数の投光素子の各々の投光動作に同期させて閾値と比較して被検出対象物が存在しているか否かを検出する制御回路とを備えた構成となっている（例えば特許文献１参照）。
【０００３】
【特許文献１】
特開平９−２７７３７号公報（第２頁、第９図）
【０００４】
【発明が解決しようとする課題】
ところで、近年、この種の多光軸光電スイッチにおいては、被検出対象物を確実に検出すべく、投光素子の配列ピッチおよび受光素子の配列ピッチを狭くすることにより、光軸間に発生する不感帯領域を小さくし、より小さい被検出対象物が存在しているか否かを検出可能にしている。
【０００５】
しかしながら、このような投光素子の配列ピッチおよび受光素子の配列ピッチを狭くする構成では、光軸間が狭くなる分、光軸間に発生する不感帯領域を小さくすることができる反面、投光素子から投じられる光がある程度の広がり角を有するために、増幅された受光信号のオーバーシュートの影響を受けることにより、検出精度が低下するという問題がある。
【０００６】
以下、図１０および図１２に示すように、５個の投光素子１ａ〜１ｅが一列に配置されてなる投光器１と、５個の受光素子２ａ〜２ｅが一列に配置されてなる受光器２とが対向して配置されてなる５光軸の多光軸光電スイッチを例にして、増幅された受光信号のオーバーシュートの影響について説明する。
【０００７】
このような構成では、投光器１において、投光素子１ａ〜１ｅは、投光素子１ａ、投光素子１ｂ、投光素子１ｃ、投光素子１ｄ、投光素子１ｅの順序にしたがって、つまり、一端側の投光素子１ａから他端側の投光素子１ｅに向かう順序にしたがって投光動作を順次行う（図１１中（ａ）参照）。一方、受光器２において、受光用制御回路（図示せず）は、受光素子２ａ〜２ｅから出力されて増幅回路（図示せず）により増幅された受光信号を投光素子１ａ〜１ｅの投光動作に同期させて入力し（図１１中（ｂ）〜（ｆ）参照）、入力された受光信号の受光量に応じた信号レベルと閾値とを比較して被検出対象物が存在しているか否かを検出する。
【０００８】
さて、ここで、投光器１における投光素子１ａ〜１ｅの配列ピッチおよび受光器２における受光素子２ａ〜２ｅの配列ピッチが、図１０に示すように、十分に広いと（図１０中Ｐ１参照）、例えば受光素子２ｂが自身に対向する投光素子１ｂから投じられた光のみを受光することになり、つまり、例えば受光素子２ｂが自身に対向する投光素子１ｂに隣接する投光素子１ａから直前に投じられた光を受光することがなく、また、仮に例えば受光素子２ｂが投光素子１ａから直前に投じられた光を受光したとしても、干渉が小さいので、受光素子２ａ〜２ｅから出力されて増幅された受光信号が相互に影響を及ぼし合うことはない（図１１中（ｇ）〜（ｌ）参照）。その結果、被検出対象物が存在していない場合には、受光素子２ａ〜２ｅから出力されて増幅された受光信号の信号レベルが確実に閾値以上となるので、受光用制御回路は、被検出対象物が存在していないことを適切に検出することができる。
【０００９】
これに対して、図１２に示すように、投光器１における投光素子１ａ〜１ｅの配列ピッチおよび受光器２における受光素子２ａ〜２ｅの配列ピッチが狭いと（図１２中Ｐ２（＜Ｐ１）参照）、例えば受光素子２ｂが自身に対向する投光素子１ｂから投じられた光を受光することに加えて、例えば受光素子２ｂが自身に対向する投光素子１ｂに隣接する投光素子１ａから直前に投じられた光をも受光してしまうことになり、受光素子２ｂの受光量が増大する場合があり、干渉が大きいと、受光素子２ａ〜２ｅから出力されて増幅された受光信号が相互に影響を及ぼし合うことになる。
【００１０】
具体的に説明すると、例えば受光素子２ｂが投光素子１ａから直前に投じられた光を受光してしまい、受光素子２ｂの受光量が増大し、干渉が大きいと、受光素子２ｂから出力されて増幅された受光信号が、その直前に受光素子２ａから出力されて増幅された受光信号のオーバーシュートの影響を受けることになり、両者が相互に打消し合うことになる。
【００１１】
そうなると、受光素子２ｂから出力されて増幅された受光信号の信号レベルが、干渉がない状態での本来の受光信号の信号レベル（図１３中（ｇ）〜（ｋ）参照）よりも低下することになる。その結果、被検出対象物が存在していない場合であっても、受光素子２ｂから出力されて増幅された受光信号の信号レベルが閾値未満となってしまうので、受光用制御回路は、被検出対象物が存在していると誤検出してしまうことになる（図１３中（ｌ）参照）。
【００１２】
以上に説明したように、投光器１における投光素子１ａ〜１ｅの配列ピッチおよび受光器２における受光素子２ａ〜２ｅの配列ピッチを狭くすると、増幅された受光信号のオーバーシュートの影響を受けることにより、被検出対象物が存在していない場合であっても、被検出対象物が存在していると誤検出してしまうという問題がある。このような問題に対しては、投光素子１ａ〜１ｅの投光動作の動作間隔を大きく設定して対応することが考えられるが、これでは、投光素子１ａ〜１ｅの全てが投光動作を行うスキャン動作を行うのに要する時間が長くなり、応答速度が遅くなるという新たな問題が発生することになる。
【００１３】
そこで、投光器における投光素子の配列ピッチおよび受光器における受光素子の配列ピッチを狭くする構成でありながらも、応答速度が遅くなることを回避する構成として、複数の投光素子を幾つかの組に分割し、干渉が小さい位置関係にある一の組に属する一の投光素子と他の組に属する他の投光素子とが同時に投光動作を行う構成が考えられる。
【００１４】
このような構成では、投光素子が１個毎に投光動作を行う構成よりも、幾つかの投光素子が同時に投光動作を行う分、スキャン動作を行うのに要する時間を短縮することができ、応答速度が遅くなることを回避することができる。
【００１５】
ところが、このような構成では、一の組に属する一の投光素子と他の組に属する他の投光素子との間では、干渉が小さいので、上記したような受光信号のオーバーシュートの問題が発生することはないが、一方、同じ組に属する隣接する投光素子同士の間では、干渉が大きいので、上記した受光信号のオーバーシュートの問題が依然として発生することになり、結局は、受光信号のオーバーシュートの影響を受けることにより、被検出対象物が存在していると誤検出してしまうという問題が解決されるには至っていない。
【００１６】
本発明は、上記した事情に鑑みてなされたものであり、その目的は、投光器における投光手段の配列ピッチおよび受光器における受光手段の配列ピッチを狭くすることにより、より小さい被検出対象物が存在しているか否かを検出することができながらも、応答速度が遅くなることを回避することができる多光軸光電スイッチを提供することにある。
【００１７】
【課題を解決するための手段】
請求項１に記載した多光軸光電スイッチは、
投光器に略一列に配置されて各々が投光動作を順次行う複数の投光手段と、
前記複数の投光手段に１対１に対応するように受光器に略一列に配置されて各々が受光信号を出力する複数の受光手段と、
前記複数の受光手段の各々から出力された受光信号を増幅する増幅手段と、
前記複数の受光手段の各々から出力されて前記増幅手段により増幅された受光信号の受光量に応じた信号レベルを前記複数の投光手段の各々の投光動作に同期させて閾値と比較して被検出対象物が存在しているか否かを検出する制御手段とを備え、
前記複数の投光手段が一連の投光動作を行うことにより、スキャン動作を行う多光軸光電スイッチにおいて、
前記複数の投光手段は、１回のスキャン動作を行う過程で、少なくとも１個以上の一の受光手段から出力される受光信号が前記一の受光手段に対応する一の投光手段を除いた他の投光手段から投じられた光の影響を受けないように連続して投光動作を行うように構成したところに特徴を有する。
【００１８】
このような構成によれば、制御手段は、複数の受光手段の各々から出力されて増幅手段により増幅された受光信号の受光量に応じた信号レベルを複数の投光手段の各々の投光動作に同期させて閾値と比較し、受光信号の信号レベルが閾値以上であれば、遮光されていないことにより、被検出対象物が存在していないと判定し、一方、受光信号の信号レベルが閾値未満であれば、遮光されていることにより、被検出対象物が存在していると判定し、このようにして被検出対象物が存在しているか否か検出することができる。
【００１９】
このとき、複数の投光手段は、１回のスキャン動作を行う過程で、少なくとも１個以上の一の受光手段から出力される受光信号が当該一の受光手段に対応する一の投光手段を除いた他の投光手段から投じられた光の影響を受けないように連続して投光動作を行うので、複数の投光手段が一端側の投光手段から他端側の投光手段に向かう順序にしたがって投光動作を順次行う従来のものとは異なって、投光器における投光手段の配列ピッチおよび受光器における受光手段の配列ピッチを狭くすることにより、より小さい被検出対象物が存在しているか否かを検出することができ、しかも、投光手段の投光動作の動作間隔を大きく設定する必要もないので、応答速度が遅くなることを回避することができる。
【００２０】
請求項２に記載した多光軸光電スイッチは、
請求項１に記載した多光軸光電スイッチにおいて、
前記複数の投光手段は、１回のスキャン動作を行う過程で、全ての一の受光手段から出力される受光信号が前記一の受光手段に対応する一の投光手段を除いた他の投光手段から投じられた光の影響を受けないように連続して投光動作を行うように構成したところに特徴を有する。
【００２１】
このような構成によれば、複数の投光手段は、１回のスキャン動作を行う過程で、全ての一の受光手段から出力される受光信号が当該一の受光手段に対応する一の投光手段を除いた他の投光手段から投じられた光の影響を受けないように連続して投光動作を行うので、少なくとも５個の投光手段が一列に配置されてなる投光器と、少なくとも５個の受光手段が一列に配置されてなる受光器とからなる構成に適用した場合に、投光器における投光手段の配列ピッチおよび受光器における受光手段の配列ピッチを狭くすることにより、より小さい被検出対象物が存在しているか否かを検出することができ、しかも、投光手段の投光動作の動作間隔を大きく設定する必要もないので、応答速度が遅くなることを回避することができる。
【００２２】
請求項３に記載した多光軸光電スイッチは、
請求項１または２に記載した多光軸光電スイッチにおいて、
前記複数の投光手段のうちの隣接する２個の投光手段は、スキャン動作を連続して行う過程で、スキャン動作の最初に受光手段から出力される受光信号が直前のスキャン動作の最後に投光動作を行った投光手段から投じられた光の影響を受けないように連続して投光動作を行うように構成したところに特徴を有する。
【００２３】
このような構成によれば、複数の投光手段のうちの隣接する２個の投光手段は、スキャン動作を連続して行う過程で、スキャン動作の最初に受光手段から出力される受光信号が直前のスキャン動作の最後に投光動作を行った投光手段から投じられた光の影響を受けないように連続して投光動作を行うので、少なくとも４個の投光手段が一列に配置されてなる投光器と、少なくとも４個の受光手段が一列に配置されてなる受光器とからなる構成に適用した場合にも、上記した請求項１に記載したものと同様にして、投光器における投光手段の配列ピッチおよび受光器における受光手段の配列ピッチを狭くすることにより、より小さい被検出対象物が存在しているか否かを検出することができ、しかも、投光手段の投光動作の動作間隔を大きく設定する必要もないので、応答速度が遅くなることを回避することができる。
【００２４】
請求項４に記載した多光軸光電スイッチは、
請求項１ないし３のいずれかに記載した多光軸光電スイッチにおいて、
前記複数の投光手段のうちの少なくとも２個以上の投光手段は、一の受光手段から出力される受光信号が前記一の受光手段に対応する一の投光手段と同時に投光動作を行う他の投光手段から投じられた光の影響を受けないように同時に投光動作を行うように構成したところに特徴を有する。
【００２５】
このような構成によれば、複数の投光手段のうちの少なくとも２個以上の投光手段は、一の受光手段から出力される受光信号が前記一の受光手段に対応する一の投光手段と同時に投光動作を行う他の投光手段から投じられた光の影響を受けないように同時に投光動作を行うので、投光手段の１個毎が投光動作を行う構成よりも、少なくとも２個以上の投光手段が同時に投光動作を行う分、スキャン動作を行うのに要する時間を短縮することができ、応答速度を向上させることができる。
【００２６】
【発明の実施の形態】
（第１実施例）
以下、本発明を５光軸の多光軸光電スイッチに適用した第１実施例について、図１および図２を参照して説明する。まず、図１は、多光軸光電スイッチの電気的な構成を機能ブロック図として示している。多光軸光電スイッチ１１は、投光器１２と受光器１３とから構成されている。
【００２７】
投光器１２は、一列に配置されてなる５個の例えばＬＥＤから構成される投光素子１２ａ〜１２ｅ（本発明でいう投光手段）、投光用制御回路１４、選択回路１５および駆動回路１６ａ〜１６ｅを備えて構成されている。投光用制御回路１４は、マイクロコンピュータを主体として構成され、投光用制御プログラムを実行することにより、投光器１２の動作全般を制御する。
【００２８】
選択回路１５は、例えば５個のラッチ回路が直列に接続されてなるシフトレジスタを備えて構成され、投光用制御回路１４からスキャン信号が入力されると、駆動回路１６ａ、駆動回路１６ｃ、駆動回路１６ｅ、駆動回路１６ｂ、駆動回路１６ｄの順序にしたがって、選択信号を駆動回路１６ａ〜駆動回路１６ｅに順次出力する。駆動回路１６ａ〜１６ｅは、選択回路１５から選択信号が入力されると、投光素子１２ａ〜１２ｅに駆動信号を出力する。投光素子１２ａ〜１２ｅは、駆動回路１６ａ〜１６ｅから駆動信号が入力されると、投光動作を行い、所定の投光時間（図２中ｔａ参照）にわたって光を投じる。このような構成により、投光素子１２ａ〜１２ｅは、投光素子１２ａ、投光素子１２ｃ、投光素子１２ｅ、投光素子１２ｂ、投光素子１２ｄの順序にしたがって投光動作を順次行う（図２中（ａ）参照）。
【００２９】
受光器１３は、一列に配置されてなる５個の例えばフォトダイオードからなる受光素子１３ａ〜１３ｅ（本発明でいう受光手段）、受光用制御回路１７（本発明でいう制御手段）、増幅回路１８ａ〜１８ｅ（本発明でいう増幅手段）、アナログスイッチ１９ａ〜１９ｅおよび選択回路２０を備えて構成されている。受光用制御回路１４は、マイクロコンピュータを主体として構成され、受光用制御プログラムを実行することにより、受光器１３の動作全般を制御する。
【００３０】
増幅回路１８ａ〜１８ｅは、受光素子１３ａ〜１３ｅから受光信号が入力されると、入力された受光信号を増幅してアナログスイッチ１９ａ〜１９ｅに出力する。選択回路２０は、上記した投光器１２における選択回路１５と同様にして、例えば５個のラッチ回路が直列に接続されてなるシフトレジスタを備えて構成され、受光用制御回路１７からスキャン信号が入力されると、アナログスイッチ１９ａ、アナログスイッチ１９ｃ、アナログスイッチ１９ｅ、アナログスイッチ１９ｂ、アナログスイッチ１９ｄの順序にしたがって、選択信号をアナログスイッチ１９ａ〜１９ｅに順次出力する。
【００３１】
アナログスイッチ１９ａ〜１９ｅは、選択回路２０から選択信号が入力されると、オン状態となり、増幅回路１８ａ〜１８ｅから増幅されて出力された受光信号を所定の入力時間（図２中ｔｂ参照）にわたって受光用制御回路１７に入力させる。この場合、アナログスイッチ１９ａ〜１９ｅが受光信号を受光用制御回路１７に入力させる入力時間は、投光器１３における投光素子１２ａ〜１２ｅが光を投じる投光時間よりも長く設定されている。このような構成により、受光用制御回路１７は、受光素子１３ａから出力されて増幅された受光信号、受光素子１３ｃから出力されて増幅された受光信号、受光素子１３ｅから出力されて増幅された受光信号、受光素子１３ｂから出力されて増幅された受光信号、受光素子１３ｄから出力されて増幅された受光信号の順序にしたがって受光信号を入力する（図２中（ｂ）〜（ｆ）参照）。
【００３２】
そして、受光用制御回路１７は、増幅回路１８ａ〜１８ｅからアナログスイッチ１９ａ〜１９ｅを通じて増幅された受光信号が入力されると、入力された受光信号の受光量に応じた信号レベルと閾値とを比較することにより、遮光されたか否かを判定し、被検出対象物が存在しているか否かを判定する。
【００３３】
尚、上記した構成において、投光器１２における投光用制御回路１４と受光器１３における受光用制御回路１７とは、同期信号を送受信することにより、投光用制御回路１４がスキャン信号を選択回路１５に出力するタイミングと、受光用制御回路１７がスキャン信号を選択回路２０に出力するタイミングとの同期を確立しており、つまり、投光器１２における投光素子１２ａ〜１２ｅが投光動作を行うタイミングと、受光器１３における受光用制御回路１７が受光信号を入力するタイミングとの同期を確立している。
【００３４】
次に上記した構成の作用について、図２も参照して説明する。ここで、図２は、上記した構成の動作をタイミングチャートとして示している。
受光器１３において、選択回路２０は、受光用制御回路１７からスキャン信号が入力されると、選択信号をアナログスイッチ１９ａに出力することにより、アナログスイッチ１９ａをオン状態にさせ、受光素子１３ａから出力される受光信号を受光用制御回路１７に入力させる。これと略同時に、投光器１２において、選択回路１５は、投光用制御回路１４からスキャン信号が入力されると、選択信号を駆動回路１６ａに出力することにより、投光素子１２ａに投光動作を行わせる。
【００３５】
これにより、投光素子１２ａから投じられた光が当該投光素子１２ａに対向する受光素子１３ａに受光されると、受光素子１３ａから受光信号が増幅回路１８ａに出力され、受光信号が増幅回路１８ａにより増幅されてアナログスイッチ１９ａを通じて受光用制御回路１７に入力され、受光信号の信号レベルが閾値と比較されることにより、被検出対象物が存在しているか否かが検出される（図２中（ｇ）参照）。
【００３６】
次いで、受光器１３において、選択回路２０は、選択信号をアナログスイッチ１９ｃに出力することにより、アナログスイッチ１９ｃをオン状態にさせ、直前に投光素子１２ａから投じられた光を受光した受光素子１３ａに隣接する受光素子１３ｂから出力される受光信号ではなく、受光素子１３ａに隣接しない受光素子１３ｃから出力される受光信号を受光用制御回路１７に入力させる。これと略同時に、投光器１２において、選択回路１５は、選択信号を駆動回路１６ｃに出力することにより、直前に光を投じた投光素子１２ａに隣接する投光素子１２ｂではなく、投光素子１２ａに隣接しない投光素子１２ｃに投光動作を行わせる。
【００３７】
これにより、投光素子１２ｃから投じられた光が当該投光素子１２ｃに対向する受光素子１３ｃに受光されると、受光素子１３ｃから受光信号が増幅回路１８ｃに出力され、受光信号が増幅回路１８ｃにより増幅されてアナログスイッチ１９ｃを通じて受光用制御回路１７に入力され、受光信号の信号レベルが閾値と比較されることにより、被検出対象物が存在しているか否かが検出される（図２中（ｉ）参照）。
【００３８】
このとき、直前に投光動作を行った投光素子は、投光素子１２ｃに隣接する投光素子１２ｂや投光素子１２ｄではなく、投光素子１２ｃに隣接しない投光素子１２ａであるので、受光素子１３ｃが投光素子１２ａから直前に投じられた光を受光することがなく、また、仮に例えば受光素子１３ｃが投光素子１２ａから直前に投じられた光を受光したとしても、干渉が小さいので、受光信号のオーバーシュートの影響を受けることはない。よって、被検出対象物が存在していない場合には、受光素子１３ｃから出力されて増幅された受光信号の信号レベルが確実に閾値以上となるので、受光用制御回路１７は、被検出対象物が存在していないことを適切に検出することができる。
【００３９】
以下、これと同様にして、受光器１３において、選択回路２０は、アナログスイッチ１９ｅ、アナログスイッチ１９ｂ、アナログスイッチ１９ｄの順序にしたがって選択信号を順次出力することにより、受光素子１３ｅから出力される受光信号、受光素子１３ｂから出力される受光信号、受光素子１３ｄから出力される受光信号の順序にしたがって、受光信号を受光用制御回路１７に入力させる。これと略同時に、投光器１２において、選択回路１５は、駆動回路１６ｅ、駆動回路１６ｂ、駆動回路１６ｄの順序にしたがって駆動信号を順次出力することにより、投光素子１２ｅ、投光素子１２ｂ、投光素子１２ｄに投光動作を順次行わせる。
【００４０】
これにより、受光素子１３ｅから出力される受光信号、受光素子１３ｂから出力される受光信号、受光素子１３ｄから出力される受光信号の信号レベルが閾値と順次比較されることにより、被検出対象物が存在しているか否かが検出される（図２中（ｋ）、（ｈ）、（ｊ）参照）。このように、１回のスキャン動作を行うに際しては、５個の投光素子１２ａ〜１２ｅのうちの隣接しない２個の投光素子が連続して投光動作を行うことになる。
【００４１】
以上に説明したように第１実施例によれば、多光軸光電スイッチ１１において、１回のスキャン動作を行う過程で、５個の投光素子１２ａ〜１２ｅのうちの隣接しない２個の投光素子が連続して投光動作を行うように構成したので、複数の投光素子が一端側の投光素子から他端側の投光素子に向かう順序にしたがって投光動作を順次行う従来のものとは異なって、投光器１２における投光素子１２ａ〜１２ｅの配列ピッチおよび受光器１３における受光素子１３ａ〜１３ｅの配列ピッチを狭くすることにより、より小さい被検出対象物が存在しているか否かを検出することができ、しかも、投光素子１２ａ〜１２ｅの投光動作の動作間隔を大きく設定する必要もないので、応答速度が遅くなることを回避することができる。
【００４２】
（第２実施例）
次に、本発明の第２実施例について、図３および図４を参照して説明する。尚、上記した第１実施例と同一部分については説明を省略し、異なる部分について説明する。この第２実施例は、４光軸の多光軸光電スイッチに適用したものである。
【００４３】
投光器２２において、投光素子２２ａ〜２２ｄは、１回のスキャン動作を行う過程で、投光素子２２ｂ、投光素子２２ｄ、投光素子２２ａ、投光素子２２ｃの順序にしたがって投光動作を順次行う（図４中（ａ）参照）。一方、受光器２３において、受光用制御回路１７は、１回のスキャン動作を行う過程で、受光素子２３ｂから出力されて増幅された受光信号、受光素子２３ｄから出力されて増幅された受光信号、受光素子２３ａから出力されて増幅された受光信号、受光素子２３ｃから出力されて増幅された受光信号の順序にしたがって受光信号を入力する（図４中（ｂ）〜（ｅ）参照）。
【００４４】
これにより、受光素子２３ｂから出力される受光信号、受光素子２３ｄから出力される受光信号、受光素子２３ａから出力される受光信号、受光素子２３ｃから出力される受光信号の信号レベルが閾値と順次比較されることにより、被検出対象物が存在しているか否かが検出される（図４中（ｆ）〜（ｉ）参照）。
【００４５】
そして、投光器２２および受光器２３は、１回のスキャン動作を完了してから所定の待機時間（図４中ｔｃ参照）が経過した後に、次のスキャン動作を行う。この場合、所定の待機時間は、スキャン動作の最初に受光素子２３ｂから出力される受光信号が直前のスキャン動作の最後に投光動作を行った投光素子２２ｃから投じられた光の影響を受けないような時間である。また、所定の待機時間を、受光用制御回路１７が受光信号を処理するための時間として使用することにより、有効に活用することができる。
【００４６】
以上に説明したように第２実施例によれば、多光軸光電スイッチ２１において、１回のスキャン動作を行う過程で、４個の投光素子２２ａ〜２２ｄのうちの隣接しない２個の投光素子が連続して投光動作を行うと共に、スキャン動作を連続して行う過程で、４個の投光素子２２ａ〜２２ｄのうちの隣接する２個の投光素子がスキャン動作の最初に受光素子２３ｂから出力される受光信号が直前のスキャン動作の最後に投光動作を行った投光素子２２ｃから投じられた光の影響を受けないように連続して投光動作を行うように構成したので、投光器２２における投光素子２２ａ〜２２ｄの配列ピッチおよび受光器２３における受光素子２３ａ〜２３ｄの配列ピッチを狭くすることにより、上記した第１実施例に記載したものと同様にして、より小さい被検出対象物が存在しているか否かを検出することができ、しかも、投光素子２２ａ〜２２ｄの投光動作の動作間隔を大きく設定する必要もないので、応答速度が遅くなることを回避することができる。
【００４７】
（第３実施例）
次に、本発明の第３実施例について、図５および図６を参照して説明する。尚、上記した第１実施例と同一部分については説明を省略し、異なる部分について説明する。この第３実施例は、１０光軸の多光軸光電スイッチに適用したものである。
【００４８】
投光器３２において、投光素子３２ａ〜３２ｊは、投光素子３２ａ〜３２ｅの組と、投光素子３２ｆ〜３２ｊの組とに分割されており、投光素子３２ａと投光素子３２ｆ、投光素子３２ｃと投光素子３２ｈ、投光素子３２ｅと投光素子３２ｊ、投光素子３２ｂと投光素子３２ｇ、投光素子３２ｄと投光素子３２ｉの順序にしたがって２個の投光素子が同時に投光動作を順次行う（図６中（ａ）参照）。この場合、投光素子３２ａと投光素子３２ｆ、投光素子３２ｃと投光素子３２ｈ、投光素子３２ｅと投光素子３２ｊ、投光素子３２ｂと投光素子３２ｇ、投光素子３２ｄと投光素子３２ｉは、それぞれ十分に離れて配置されているので、２個の投光素子が同時に投光動作を行ったとしても、干渉が発生することはない。
【００４９】
一方、受光器３３において、受光用制御回路１７は、受光素子３３ａから出力されて増幅された受光信号と受光素子３３ｆから出力されて増幅された受光信号、受光素子３３ｃから出力されて増幅された受光信号と受光素子３３ｈから出力されて増幅された受光信号、受光素子３３ｅから出力されて増幅された受光信号と受光素子３３ｊから出力されて増幅された受光信号、受光素子３３ｂから出力されて増幅された受光信号と受光素子３３ｇから出力されて増幅された受光信号、受光素子３３ｄから出力されて増幅された受光信号と受光素子３３ｉから出力されて増幅された受光信号の順序にしたがって２個の受光素子から出力されて増幅された受光信号を同時に入力する（図６中（ｂ）〜（ｆ）参照）。
【００５０】
これにより、受光素子３３ａから出力される受光信号と受光素子３３ｆから出力される受光信号、受光素子３３ｃから出力される受光信号と受光素子３３ｈから出力される受光信号、受光素子３３ｅから出力される受光信号と受光素子３３ｊから出力される受光信号、受光素子３３ｂから出力される受光信号と受光素子３３ｇから出力される受光信号、受光素子３３ｄから出力される受光信号と受光素子３３ｉから出力される受光信号の信号レベルが閾値と順次比較されることにより、被検出対象物が存在しているか否かが検出される（図６中（ｇ）〜（ｋ）参照）。
【００５１】
以上に説明したように第３実施例によれば、多光軸光電スイッチ３１において、１回のスキャン動作を行う過程で、１０個の投光素子３２ａ〜３２ｊのうちの隣接しない２個の投光素子が連続して投光動作を行うように構成したので、投光器３２における投光素子３２ａ〜３２ｊの配列ピッチおよび受光器３３における受光素子３３ａ〜３３ｊの配列ピッチを狭くすることにより、上記した第１実施例に記載したものと同様にして、より小さい被検出対象物が存在しているか否かを検出することができる。
【００５２】
そして、この場合は、２個の投光素子が同時に投光動作を行うように構成したので、投光素子３２ａ〜３２ｊの１個毎が投光動作を行う構成よりも、２個の投光素子が同時に投光動作を行う分、スキャン動作を行うのに要する時間を短縮することができ、応答速度を向上させることができる。
【００５３】
（第４実施例）
次に、本発明の第４実施例について、図７および図８を参照して説明する。尚、上記した第２実施例と同一部分については説明を省略し、異なる部分について説明する。この第４実施例は、８光軸の多光軸光電スイッチに適用したものである。
【００５４】
投光器４２において、投光素子４２ａ〜４２ｈは、投光素子４２ａ〜４２ｄの組と、投光素子４２ｅ〜４２ｈの組とに分割されており、投光素子４２ｂと投光素子４２ｆ、投光素子４２ｄと投光素子４２ｈ、投光素子４２ａと投光素子４２ｅ、投光素子４２ｃと投光素子４２ｇの順序にしたがって２個の投光素子が同時に投光動作を順次行う（図８中（ａ）参照）。この場合、投光素子４２ｂと投光素子４２ｆ、投光素子４２ｄと投光素子４２ｈ、投光素子４２ａと投光素子４２ｅ、投光素子４２ｃと投光素子４２ｇは、それぞれ十分に離れて配置されているので、２個の投光素子が同時に投光動作を行ったとしても、干渉が発生することはない。
【００５５】
一方、受光器４３において、受光用制御回路１７は、受光素子４３ｂから出力されて増幅された受光信号と受光素子４３ｆから出力されて増幅された受光信号、受光素子４３ｄから出力されて増幅された受光信号と受光素子４３ｈから出力されて増幅された受光信号、受光素子４３ａから出力されて増幅された受光信号と受光素子４３ｅから出力されて増幅された受光信号、受光素子４３ｃから出力されて増幅された受光信号と受光素子４３ｇから出力されて増幅された受光信号の順序にしたがって２個の受光素子から出力されて増幅された受光信号を同時に入力する（図８中（ｂ）〜（ｅ）参照）。
【００５６】
これにより、受光素子４３ｂから出力される受光信号と受光素子４３ｆから出力される受光信号、受光素子４３ｄから出力される受光信号と受光素子４３ｈから出力される受光信号、受光素子４３ａから出力される受光信号と受光素子４３ｅから出力される受光信号、受光素子４３ｃから出力される受光信号と受光素子４３ｇから出力される受光信号の信号レベルが閾値と順次比較されることにより、被検出対象物が存在しているか否かが検出される（図８中（ｆ）〜（ｉ）参照）。
【００５７】
そして、投光器４２および受光器４３は、この場合も、１回のスキャン動作を完了してから所定の待機時間（図８中ｔｃ参照）が経過した後に、次のスキャン動作を行う。この場合も、所定の待機時間は、スキャン動作の最初に受光素子４３ｂ，４３ｆから出力される受光信号が直前のスキャン動作の最後に投光動作を行った投光素子４２ｃ，４２ｇから投じられた光の影響を受けないような時間である。また、この場合も、所定の待機時間を、受光用制御回路１７が受光信号を処理するための時間として使用することにより、有効に活用することができる。
【００５８】
以上に説明したように第４実施例によれば、多光軸光電スイッチ４１において、１回のスキャン動作を行う過程で、８個の投光素子４２ａ〜４２ｈのうちの隣接しない２個の投光素子が連続して投光動作を行うと共に、スキャン動作を連続して行う過程で、８個の投光素子４２ａ〜４２ｈのうちの隣接する２個の投光素子がスキャン動作の最初に受光素子４３ｂ，４３ｆから出力される受光信号が直前のスキャン動作の最後に投光動作を行った投光素子４２ｃ，４２ｇから投じられた光の影響を受けないように連続して投光動作を行うように構成したので、投光器４２における投光素子４２ａ〜４２ｈの配列ピッチおよび受光器４３における受光素子４３ａ〜４３ｈの配列ピッチを狭くすることにより、上記した第２実施例に記載したものと同様にして、より小さい被検出対象物が存在しているか否かを検出することができる。
【００５９】
そして、この場合も、２個の投光素子が同時に投光動作を行うように構成したので、投光素子４２ａ〜４２ｈの１個毎が投光動作を行う構成よりも、２個の投光素子が同時に投光動作を行う分、スキャン動作を行うのに要する時間を短縮することができ、応答速度を向上させることができる。
【００６０】
（第５実施例）
次に、本発明の第５実施例について、図９を参照して説明する。尚、上記した第１実施例と同一部分については説明を省略し、異なる部分について説明する。この第５実施例は、上記した第１実施例のものと構成が同じであるが、投光器１２において、投光素子１２ｂ、投光素子１２ｃ、投光素子１２ｄ、投光素子１２ｅ、投光素子１２ａの順序にしたがって投光動作を順次行う（図９中（ａ）参照）。
【００６１】
一方、受光器１３において、受光用制御回路１７は、受光素子１３ｂから出力されて増幅された受光信号、受光素子１３ｃから出力されて増幅された受光信号、受光素子１３ｄから出力されて増幅された受光信号、受光素子１３ｅから出力されて増幅された受光信号、受光素子１３ａから出力されて増幅された受光信号の順序にしたがって受光信号を入力する（図９中（ｂ）〜（ｅ）参照）。
【００６２】
この場合、投光素子１２ｅと投光素子１２ａとの間の投光動作の動作間隔（図９中ｔｅ参照）は、投光素子１２ｅと投光素子１２ａとが隣接しないので、投光素子１２ｂと投光素子１２ｃとの間の投光動作の動作間隔、投光素子１２ｃと投光素子１２ｄとの間の投光動作の動作間隔および投光素子１２ｄと投光素子１２ｅとの間の投光動作の動作間隔（図９中ｔｄ参照）よりも小さく設定することができ、その分、投光素子１２ａ〜１２ｅの全ての投光動作の動作間隔を一律に図９中ｔｄに相当する時間に設定するものよりも、応答速度を向上させることができる。
【００６３】
（その他の実施例）
本発明は、上記した実施例にのみ限定されるものではなく、以下のように変形または拡張することができる。
各実施例において、投光素子が投光動作を行う順序は、一の受光素子から出力される受光信号が一の受光素子に対応する一の投光素子を除いた他の投光素子から投じられた光の影響を受けないという条件を満たすものであれば、他の順序であっても良い。
【００６４】
第１実施例において、投光素子および受光素子の個数が６個以上であっても良く、第２実施例において、投光素子および受光素子の個数が５個以上であっても良い。第３実施例において、投光素子および受光素子の個数が１１個以上であっても良く、３個以上の投光素子が同時に投光動作を行う構成であっても良い。第４実施例において、投光素子および受光素子の個数が９個以上であっても良く、３個以上の投光素子が同時に投光動作を行う構成であっても良い。
【００６５】
【発明の効果】
以上の説明から明らかなように、本発明の多光軸光電スイッチによれば、複数の投光手段が、１回のスキャン動作を行う過程で、一の受光手段から出力される受光信号が当該一の受光手段に対応する一の投光手段を除いた他の投光手段から投じられた光の影響を受けないように連続して投光動作を行うように構成したので、投光器における投光手段の配列ピッチおよび受光器における受光手段の配列ピッチを狭くすることにより、より小さい被検出対象物が存在しているか否かを検出することができ、しかも、投光手段の投光動作の動作間隔を大きく設定する必要もないので、応答速度が遅くなることを回避することができる。
【図面の簡単な説明】
【図１】本発明の第１実施例を示す機能ブロック図
【図２】タイミングチャート
【図３】本発明の第２実施例を示す機能ブロック図
【図４】図２相当図
【図５】本発明の第３実施例を示す機能ブロック図
【図６】図２相当図
【図７】本発明の第４実施例を示す機能ブロック図
【図８】図２相当図
【図９】本発明の第５実施例を示すタイミングチャート
【図１０】従来の一例を示す図
【図１１】図２相当図
【図１２】従来の他の例を示す図
【図１３】図２相当図
【符号の説明】
図面中、１１は多光軸光電スイッチ、１２は投光器、１２ａ〜１２ｅは投光素子（投光手段）、１３は受光器、１３ａ〜１３ｅは受光素子（受光手段）、１７は受光用制御回路（制御手段）、１８ａ〜１８ｅは増幅回路（増幅手段）、２１は多光軸光電スイッチ、２２は投光器、２２ａ〜２２ｄは投光素子（投光手段）、２３は受光器、２３ａ〜２３ｄは受光素子（受光手段）、３１は多光軸光電スイッチ、３２は投光器、３２ａ〜３２ｊは投光素子（投光手段）、３３は受光器、３３ａ〜３３ｊは受光素子（受光手段）、４１は多光軸光電スイッチ、４２は投光器、４２ａ〜４２ｈは投光素子（投光手段）、４３は受光器、４３ａ〜４３ｈは受光素子（受光手段）である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention includes a plurality of light emitting means arranged substantially in a line in the light emitting device, and a plurality of light receiving means arranged in a substantially light receiving device in a one-to-one correspondence with the plurality of light emitting means, The signal level corresponding to the received light amount of the amplified light receiving signal output from each of the plurality of light receiving means is synchronized with each light emitting operation of the plurality of light emitting means and compared with a threshold value, and the detection target is present. The present invention relates to a multi-optical axis photoelectric switch for detecting whether or not the operation is performed.
[0002]
[Prior art]
A conventional multi-optical axis photoelectric switch includes a plurality of light emitting elements which are arranged substantially in a line in a light emitting element and sequentially perform light emitting operations, and a light receiving element is provided on a light receiving element so as to correspond to the plurality of light emitting elements on a one-to-one basis. A plurality of light receiving elements arranged in a row and each outputting a light receiving signal, an amplifier circuit for amplifying the light receiving signal output from each of the plurality of light receiving elements, and an amplifier circuit output from each of the plurality of light receiving elements A control circuit for synchronizing a signal level corresponding to the amount of received light of the amplified light receiving signal with each light emitting operation of the plurality of light emitting elements and comparing it with a threshold value to detect whether an object to be detected is present or not. (For example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-9-27737 (page 2, FIG. 9)
[0004]
[Problems to be solved by the invention]
By the way, in recent years, in this type of multi-optical axis photoelectric switch, in order to surely detect an object to be detected, the arrangement pitch of the light projecting elements and the array pitch of the light receiving elements are narrowed, so that the light is generated between the optical axes. The dead zone area is reduced so that it is possible to detect whether or not a smaller detection target exists.
[0005]
However, in such a configuration in which the arrangement pitch of the light projecting elements and the arrangement pitch of the light receiving elements are narrowed, the dead zone region generated between the optical axes can be reduced by an amount corresponding to the narrowing between the optical axes. There is a problem that the detection accuracy is reduced due to the influence of overshoot of the amplified light receiving signal because the light projected from the light source has a certain spread angle.
[0006]
Hereinafter, as shown in FIGS. 10 and 12, a light projector 1 in which five light emitting elements 1a to 1e are arranged in one line and a light receiver 2 in which five light emitting elements 2a to 2e are arranged in one line The influence of the overshoot of the amplified light receiving signal will be described with reference to an example of a multi-optical axis photoelectric switch having five optical axes in which the optical switches are opposed to each other.
[0007]
In such a configuration, in the light projector 1, the light projecting elements 1a to 1e are arranged in the order of the light projecting element 1a, the light projecting element 1b, the light projecting element 1c, the light projecting element 1d, and the light projecting element 1e. The light emitting operation is sequentially performed according to the order from the light emitting element 1a on the side to the light emitting element 1e on the other end (see (a) in FIG. 11). On the other hand, in the light receiver 2, a light receiving control circuit (not shown) projects light receiving signals output from the light receiving elements 2a to 2e and amplified by an amplifier circuit (not shown) to the light emitting elements 1a to 1e. Input in synchronization with the operation (see (b) to (f) in FIG. 11), and compare the signal level corresponding to the amount of received light of the received light signal with a threshold value to determine whether an object to be detected exists. Detect whether or not.
[0008]
Now, if the arrangement pitch of the light emitting elements 1a to 1e in the light projector 1 and the arrangement pitch of the light receiving elements 2a to 2e in the light receiver 2 are sufficiently wide as shown in FIG. 10 (see P1 in FIG. 10). For example, the light receiving element 2b receives only the light emitted from the light emitting element 1b facing itself, that is, for example, the light receiving element 2b receives light from the light emitting element 1a adjacent to the light emitting element 1b facing itself. The light received immediately before is not received, and even if, for example, the light receiving element 2b receives the light immediately before projected from the light emitting element 1a, the interference is small, and the light output from the light receiving elements 2a to 2e is not received. The received and amplified light receiving signals do not affect each other (see (g) to (l) in FIG. 11). As a result, when the object to be detected does not exist, the signal level of the amplified light receiving signal output from the light receiving elements 2a to 2e surely exceeds the threshold value. It is possible to appropriately detect that the object is not present.
[0009]
On the other hand, as shown in FIG. 12, when the arrangement pitch of the light emitting elements 1a to 1e in the light projector 1 and the arrangement pitch of the light receiving elements 2a to 2e in the light receiver 2 are narrow (see P2 (<P1) in FIG. 12). ), For example, in addition to the light receiving element 2b receiving light emitted from the light emitting element 1b facing itself, for example, the light receiving element 2b immediately before the light emitting element 1a adjacent to the light emitting element 1b facing itself. The light received by the light receiving element 2b may also be received, and the light receiving amount of the light receiving element 2b may increase. When the interference is large, the light receiving signals output from the light receiving elements 2a to 2e and amplified are mutually reciprocated. They will influence each other.
[0010]
To be more specific, for example, the light receiving element 2b receives the light that has just been projected from the light emitting element 1a, and the light receiving amount of the light receiving element 2b increases. If the interference is large, the light is output from the light receiving element 2b. The amplified light receiving signal is affected by the overshoot of the amplified light receiving signal output from the light receiving element 2a immediately before, so that the two cancel each other out.
[0011]
Then, the signal level of the light receiving signal output from the light receiving element 2b and amplified is lower than the signal level of the original light receiving signal without interference (see (g) to (k) in FIG. 13). become. As a result, even when the object to be detected does not exist, the signal level of the amplified light receiving signal output from the light receiving element 2b becomes lower than the threshold value. It is erroneously detected that the target object exists (see (l) in FIG. 13).
[0012]
As described above, when the arrangement pitch of the light projecting elements 1a to 1e in the light projector 1 and the arrangement pitch of the light receiving elements 2a to 2e in the light receiver 2 are reduced, the amplified light receiving signal is affected by overshoot. However, there is a problem that even when the detection target object does not exist, the detection target object is erroneously detected as existing. It is conceivable to cope with such a problem by setting a large operation interval of the light projecting operation of the light projecting elements 1a to 1e. In this case, however, all of the light projecting elements 1a to 1e perform the light projecting operation. The time required to perform the scan operation for performing the above operation becomes longer, and a new problem occurs in that the response speed becomes slower.
[0013]
Therefore, as a configuration for narrowing the arrangement pitch of the light emitting elements in the light projector and the arrangement pitch of the light receiving elements in the light receiver, a configuration in which a plurality of light emitting elements A configuration is considered in which one light-emitting element belonging to one set and another light-emitting element belonging to another set simultaneously perform a light emitting operation.
[0014]
In such a configuration, the time required for performing the scanning operation can be shortened by an amount that several light emitting elements perform the light emitting operation at the same time as compared with the configuration in which the light emitting elements perform the light emitting operation one by one. And the response speed can be prevented from becoming slow.
[0015]
However, in such a configuration, since the interference between one light emitting element belonging to one set and another light emitting element belonging to another set is small, the above-described problem of overshoot of the received light signal occurs. However, since the interference between adjacent light emitting elements belonging to the same group is large, the above-described problem of overshoot of the received light signal still occurs. Due to the influence of the overshoot of the signal, the problem of erroneously detecting the presence of the detection target has not been solved.
[0016]
The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the arrangement pitch of the light projecting means in the light projector and the arrangement pitch of the light receiving means in the light receiver so that a smaller detection target object can be obtained. It is an object of the present invention to provide a multi-optical axis photoelectric switch which can detect whether or not it is present, but can avoid a decrease in response speed.
[0017]
[Means for Solving the Problems]
The multi-optical axis photoelectric switch according to claim 1,
A plurality of light emitting means arranged substantially in a row in the light emitter, each of which sequentially performs light emitting operation,
A plurality of light receiving means arranged substantially in a line in a light receiver so as to correspond to the plurality of light emitting means on a one-to-one basis, each of which outputs a light receiving signal;
Amplifying means for amplifying a light receiving signal output from each of the plurality of light receiving means,
A signal level corresponding to the amount of received light of the received light signal output from each of the plurality of light receiving means and amplified by the amplifying means is compared with a threshold value in synchronization with the light emitting operation of each of the plurality of light emitting means. Control means for detecting whether an object to be detected exists or not,
In the multi-optical axis photoelectric switch which performs a scanning operation by the plurality of light emitting means performing a series of light emitting operations,
In the process of performing one scan operation, the plurality of light emitting units exclude one light emitting unit corresponding to the one light receiving unit when a light receiving signal output from at least one or more one of the light receiving units is removed. The present invention is characterized in that a light emitting operation is continuously performed so as not to be affected by light emitted from other light emitting means.
[0018]
According to such a configuration, the control means controls the light emitting operation of each of the plurality of light emitting means to a signal level corresponding to the amount of received light of the light receiving signal output from each of the plurality of light receiving means and amplified by the amplifying means. In synchronization with the threshold, if the signal level of the light receiving signal is equal to or higher than the threshold, it is determined that the object to be detected does not exist because the light is not shielded, while the signal level of the light receiving signal is equal to the threshold. If it is less than 1, it is determined that the object to be detected is present because the light is shielded, and thus it is possible to detect whether the object to be detected is present.
[0019]
At this time, in the process of performing one scan operation, the plurality of light emitting units are configured such that a light receiving signal output from at least one or more one light receiving unit transmits one light emitting unit corresponding to the one light receiving unit. Since the light emitting operation is continuously performed so as not to be affected by the light emitted from the other light emitting means except for the plurality of light emitting means, the plurality of light emitting means can be changed from the light emitting means on one end to the light emitting means on the other end. Unlike the conventional one in which the light emitting operations are sequentially performed in the order of heading, a smaller object to be detected exists by reducing the arrangement pitch of the light emitting means in the light emitter and the arrangement pitch of the light receiving means in the light receiver. It is possible to detect whether or not the operation is performed, and it is not necessary to set a large operation interval of the light projecting operation of the light projecting means. Therefore, it is possible to avoid a slow response speed.
[0020]
The multi-optical axis photoelectric switch according to claim 2 is
The multi-optical axis photoelectric switch according to claim 1,
In the process of performing one scan operation, the plurality of light emitting units receive light signals output from all one of the light receiving units except for the one light emitting unit corresponding to the one light receiving unit. The present invention is characterized in that a light emitting operation is continuously performed so as not to be affected by the light emitted from the light means.
[0021]
According to such a configuration, in the process of performing one scan operation, the plurality of light emitting units are configured such that light receiving signals output from all one light receiving units correspond to one light emitting unit corresponding to the one light receiving unit. Since the light emitting operation is continuously performed so as not to be affected by the light emitted from other light emitting means except for the light emitting means, at least five light emitting means are arranged in a line, and at least five light emitting means are arranged. When the present invention is applied to a configuration including a plurality of light receiving units arranged in a line, the arrangement pitch of the light emitting unit in the light emitting unit and the arrangement pitch of the light receiving units in the light receiving unit are narrowed, so that a smaller detected object can be obtained. It is possible to detect whether an object is present or not, and it is not necessary to set a large operation interval of the light emitting operation of the light emitting means, so that it is possible to avoid a slow response speed.
[0022]
The multi-optical axis photoelectric switch according to claim 3,
The multi-optical axis photoelectric switch according to claim 1 or 2,
In the process of continuously performing the scanning operation, the adjacent two light emitting units of the plurality of light emitting units receive a light receiving signal output from the light receiving unit at the beginning of the scanning operation at the end of the immediately preceding scanning operation. It is characterized in that the light emitting device is configured to perform the light emitting operation continuously so as not to be affected by the light emitted from the light emitting means that has performed the light emitting operation.
[0023]
According to such a configuration, two adjacent light emitting units of the plurality of light emitting units receive light signals output from the light receiving unit at the beginning of the scanning operation in the process of continuously performing the scanning operation. Since the light emitting operation is continuously performed so as not to be affected by the light emitted from the light emitting means that performed the light emitting operation at the end of the immediately preceding scanning operation, at least four light emitting means are arranged in a line. In a case where the present invention is applied to a configuration including a light projector formed of a plurality of light receiving devices and at least four light receiving devices arranged in a line, the light emitting device in the light projector can be configured in the same manner as described in claim 1 above. By narrowing the arrangement pitch of the light receiving means in the light receiver and the arrangement pitch of the light receiving means, it is possible to detect whether or not a smaller detection target exists, and furthermore, the operation interval of the light emitting operation of the light emitting means Large There is no need, it is possible to prevent the response speed becomes slow.
[0024]
The multi-optical axis photoelectric switch according to claim 4,
The multi-optical axis photoelectric switch according to any one of claims 1 to 3,
At least two or more of the plurality of light emitting means perform a light emitting operation at the same time as the one light emitting means corresponding to the one light receiving means when a light receiving signal output from one light receiving means is provided. The present invention is characterized in that a light-projecting operation is performed at the same time so as not to be affected by light emitted from other light-projecting means.
[0025]
According to such a configuration, at least two or more of the plurality of light projecting means are arranged so that a light receiving signal output from one light receiving means corresponds to one light receiving means corresponding to the one light receiving means. At the same time, since the light projecting operation is performed simultaneously so as not to be affected by the light projected from the other light projecting means that performs the light projecting operation, at least one light emitting means performs the light projecting operation at least. The time required for performing the scanning operation can be shortened and the response speed can be improved because two or more light emitting units simultaneously perform the light emitting operation.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to a multi-optical axis photoelectric switch having five optical axes will be described with reference to FIGS. First, FIG. 1 shows a functional block diagram of an electrical configuration of a multi-optical axis photoelectric switch. The multi-optical axis photoelectric switch 11 includes a light projector 12 and a light receiver 13.
[0027]
The light projector 12 includes light emitting elements 12a to 12e (light emitting means according to the present invention) each including, for example, five LEDs arranged in a line, a light emitting control circuit 14, a selecting circuit 15, and a driving circuit 16a to 16e. 16e. The light projecting control circuit 14 is mainly composed of a microcomputer, and controls the overall operation of the light projecting device 12 by executing a light projecting control program.
[0028]
The selection circuit 15 includes, for example, a shift register in which five latch circuits are connected in series, and when a scan signal is input from the light emission control circuit 14, the drive circuits 16a, 16c, and The selection signal is sequentially output to the driving circuits 16a to 16e in accordance with the order of the circuit 16e, the driving circuit 16b, and the driving circuit 16d. When the selection signal is input from the selection circuit 15, the drive circuits 16a to 16e output the drive signals to the light emitting elements 12a to 12e. When the drive signals are input from the drive circuits 16a to 16e, the light emitting elements 12a to 12e perform a light emitting operation and emit light over a predetermined light emitting time (see ta in FIG. 2). With such a configuration, the light projecting elements 12a to 12e sequentially perform the light projecting operation in the order of the light projecting element 12a, the light projecting element 12c, the light projecting element 12e, the light projecting element 12b, and the light projecting element 12d (FIG. 2 (a)).
[0029]
The light receiver 13 includes five light receiving elements 13a to 13e (light receiving means according to the present invention) composed of, for example, photodiodes arranged in a line, a light receiving control circuit 17 (control means according to the present invention), and an amplifying circuit 18a. To 18e (amplifying means in the present invention), analog switches 19a to 19e, and a selection circuit 20. The light receiving control circuit 14 is mainly composed of a microcomputer, and controls the overall operation of the light receiver 13 by executing a light receiving control program.
[0030]
When the light receiving signals are input from the light receiving elements 13a to 13e, the amplifier circuits 18a to 18e amplify the input light receiving signals and output the amplified signals to the analog switches 19a to 19e. The selection circuit 20 includes a shift register in which, for example, five latch circuits are connected in series in the same manner as the selection circuit 15 in the above-described light projector 12. The scan signal is input from the light receiving control circuit 17. Then, the selection signal is sequentially output to the analog switches 19a to 19e according to the order of the analog switches 19a, 19c, 19e, 19b, and 19d.
[0031]
When a selection signal is input from the selection circuit 20, the analog switches 19a to 19e are turned on, and the analog switches 19a to 19e apply the received light signals amplified and output from the amplification circuits 18a to 18e for a predetermined input time (see tb in FIG. 2). It is input to the light receiving control circuit 17. In this case, the input time during which the analog switches 19a to 19e input the light receiving signal to the light receiving control circuit 17 is set longer than the light emitting time during which the light emitting elements 12a to 12e in the light emitting device 13 emit light. With such a configuration, the light receiving control circuit 17 outputs the amplified light receiving signal output from the light receiving element 13a, the amplified light receiving signal output from the light receiving element 13c, and the amplified light receiving signal output from the light receiving element 13e. The light receiving signal is input in accordance with the order of the signal, the light receiving signal output from the light receiving element 13b and amplified, and the light receiving signal output from the light receiving element 13d and amplified (see (b) to (f) in FIG. 2).
[0032]
When the light receiving control circuit 17 receives the amplified light receiving signal from the amplifier circuits 18a to 18e through the analog switches 19a to 19e, the light receiving control circuit 17 compares the signal level corresponding to the received light amount of the received light receiving signal with a threshold. By doing so, it is determined whether or not the light is shielded, and it is determined whether or not the detection target exists.
[0033]
In the above-described configuration, the light emitting control circuit 14 in the light emitting device 12 and the light receiving control circuit 17 in the light receiving device 13 transmit and receive a synchronization signal. Is synchronized with the timing at which the light receiving control circuit 17 outputs the scan signal to the selection circuit 20, that is, the timing at which the light emitting elements 12a to 12e of the light projector 12 perform the light emitting operation. The synchronization with the timing at which the light receiving control circuit 17 in the light receiver 13 inputs a light receiving signal is established.
[0034]
Next, the operation of the above configuration will be described with reference to FIG. Here, FIG. 2 shows the operation of the above configuration as a timing chart.
In the photodetector 13, when the scan signal is input from the light receiving control circuit 17, the selection circuit 20 outputs the selection signal to the analog switch 19a to turn on the analog switch 19a and output from the light receiving element 13a. The received light signal is input to the light receiving control circuit 17. At substantially the same time, in the light projector 12, the selection circuit 15 outputs the selection signal to the drive circuit 16a when the scan signal is input from the light projection control circuit 14, thereby causing the light emitting element 12a to emit light. Let it do.
[0035]
Thus, when the light emitted from the light emitting element 12a is received by the light receiving element 13a facing the light emitting element 12a, a light receiving signal is output from the light receiving element 13a to the amplifier circuit 18a, and the light receiving signal is output to the amplifier circuit 18a. The signal is input to the light receiving control circuit 17 through the analog switch 19a, and the signal level of the light receiving signal is compared with a threshold value to detect whether or not the detection target is present (FIG. 2). (G)).
[0036]
Next, in the photodetector 13, the selection circuit 20 outputs the selection signal to the analog switch 19c to turn on the analog switch 19c, and the photodetector 13a that has received the light emitted from the light projecting element 12a immediately before. The light receiving signal output from the light receiving element 13c not adjacent to the light receiving element 13a is input to the light receiving control circuit 17 instead of the light receiving signal output from the light receiving element 13b adjacent to the light receiving element 13b. At substantially the same time, in the light projector 12, the selection circuit 15 outputs a selection signal to the drive circuit 16c, so that the light emission element 12a is not used, instead of the light emission element 12b adjacent to the light emission element 12a that has just emitted light. The light emitting element 12c that is not adjacent to the light emitting element performs a light emitting operation.
[0037]
Accordingly, when the light emitted from the light emitting element 12c is received by the light receiving element 13c facing the light emitting element 12c, a light receiving signal is output from the light receiving element 13c to the amplifier circuit 18c, and the light receiving signal is output to the amplifier circuit 18c. The signal is input to the light receiving control circuit 17 through the analog switch 19c, and the signal level of the light receiving signal is compared with a threshold value to detect whether or not the detection target exists (FIG. 2). (See (i)).
[0038]
At this time, the light emitting element that has just performed the light emitting operation is not the light emitting element 12b or the light emitting element 12d adjacent to the light emitting element 12c, but the light emitting element 12a that is not adjacent to the light emitting element 12c. Even if the light receiving element 13c does not receive the light immediately before projected from the light emitting element 12a, the interference is small even if the light receiving element 13c receives the light immediately before projected from the light emitting element 12a. Therefore, there is no influence of the overshoot of the received light signal. Therefore, when the detection target object does not exist, the signal level of the light reception signal output from the light receiving element 13c and amplified is surely equal to or higher than the threshold value. Can be properly detected.
[0039]
Hereinafter, similarly, in the photodetector 13, the selection circuit 20 sequentially outputs the selection signal in accordance with the order of the analog switch 19e, the analog switch 19b, and the analog switch 19d, thereby receiving the light output from the light receiving element 13e. The light receiving signal is input to the light receiving control circuit 17 in accordance with the order of the signal, the light receiving signal output from the light receiving element 13b, and the light receiving signal output from the light receiving element 13d. At substantially the same time, in the light projector 12, the selection circuit 15 sequentially outputs drive signals in the order of the drive circuit 16e, the drive circuit 16b, and the drive circuit 16d, so that the light projecting elements 12e, 12b, The light emitting operation is sequentially performed by the element 12d.
[0040]
As a result, the signal levels of the light receiving signal output from the light receiving element 13e, the light receiving signal output from the light receiving element 13b, and the light receiving signal output from the light receiving element 13d are sequentially compared with the threshold value. It is detected whether or not it exists (see (k), (h), and (j) in FIG. 2). As described above, when performing one scan operation, two non-adjacent light projecting elements of the five light projecting elements 12a to 12e continuously perform the light projecting operation.
[0041]
As described above, according to the first embodiment, in the multi-optical axis photoelectric switch 11, in the process of performing one scanning operation, two non-adjacent ones of the five light emitting elements 12a to 12e. Since the light emitting elements are configured to perform the light emitting operation continuously, a plurality of light emitting elements sequentially perform the light emitting operation in order from the light emitting element on one end to the light emitting element on the other end. Unlike the above, by narrowing the arrangement pitch of the light emitting elements 12a to 12e in the light projector 12 and the arrangement pitch of the light receiving elements 13a to 13e in the light receiver 13, it is determined whether or not a smaller detection target exists. Can be detected, and it is not necessary to set a large operation interval of the light projecting operations of the light projecting elements 12a to 12e. Therefore, it is possible to avoid a decrease in response speed.
[0042]
(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. The description of the same parts as in the first embodiment will be omitted, and different parts will be described. The second embodiment is applied to a multi-optical axis photoelectric switch having four optical axes.
[0043]
In the light projector 22, the light projecting elements 22a to 22d sequentially perform the light projecting operation in the order of the light projecting element 22b, the light projecting element 22d, the light projecting element 22a, and the light projecting element 22c in the process of performing one scan operation. (See FIG. 4A). On the other hand, in the light receiving device 23, the light receiving control circuit 17 performs the light receiving signal output from the light receiving element 23b and amplified, the light receiving signal output from the light receiving element 23d and amplified in the process of performing one scan operation. Light receiving signals are input in accordance with the order of the light receiving signal output from the light receiving element 23a and amplified, and the light receiving signal output and amplified from the light receiving element 23c (see (b) to (e) in FIG. 4).
[0044]
Thus, the signal levels of the light receiving signal output from the light receiving element 23b, the light receiving signal output from the light receiving element 23d, the light receiving signal output from the light receiving element 23a, and the light receiving signal output from the light receiving element 23c are sequentially compared with the threshold. As a result, it is detected whether or not the detection target exists (see (f) to (i) in FIG. 4).
[0045]
Then, the light emitter 22 and the light receiver 23 perform the next scan operation after a predetermined standby time (see tc in FIG. 4) has elapsed after the completion of one scan operation. In this case, the predetermined standby time is affected by the light emitted from the light emitting element 22c that has performed the light emitting operation at the end of the immediately preceding scanning operation, when the light receiving signal output from the light receiving element 23b at the beginning of the scanning operation is affected. Not like time. In addition, by using the predetermined standby time as a time for the light receiving control circuit 17 to process the light receiving signal, it can be effectively utilized.
[0046]
As described above, according to the second embodiment, in the process of performing one scanning operation in the multi-optical axis photoelectric switch 21, two non-adjacent two of the four light emitting elements 22a to 22d are projected. In the process in which the light emitting elements continuously perform the light emitting operation and continuously perform the scanning operation, two adjacent light emitting elements among the four light emitting elements 22a to 22d receive light at the beginning of the scanning operation. The light emitting operation is continuously performed so that the light receiving signal output from the element 23b is not affected by the light emitted from the light emitting element 22c that has performed the light emitting operation at the end of the immediately preceding scan operation. Therefore, by narrowing the arrangement pitch of the light projecting elements 22a to 22d in the light projector 22 and the arrangement pitch of the light receiving elements 23a to 23d in the light receiver 23, the same as described in the first embodiment, Since it is possible to detect whether or not the detection target object is present, and it is not necessary to set a large operation interval of the light projecting operations of the light projecting elements 22a to 22d, it is possible to reduce the response speed. Can be avoided.
[0047]
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. The description of the same parts as in the first embodiment will be omitted, and different parts will be described. The third embodiment is applied to a multi-optical axis photoelectric switch having 10 optical axes.
[0048]
In the light projector 32, the light projecting elements 32a to 32j are divided into a set of light projecting elements 32a to 32e and a set of light projecting elements 32f to 32j, and the light projecting element 32a, the light projecting element 32f, and the light projecting element 32c and the light emitting element 32h, two light emitting elements simultaneously emit light in the order of the light emitting element 32e and the light emitting element 32g, the light emitting element 32b and the light emitting element 32g, and the light emitting element 32d and the light emitting element 32i. The operation is performed sequentially (see (a) in FIG. 6). In this case, the light emitting elements 32a and 32f, the light emitting elements 32c and 32h, the light emitting elements 32e and 32j, the light emitting elements 32b and 32g, and the light emitting elements 32d and 32d Since the elements 32i are sufficiently separated from each other, no interference occurs even when the two light emitting elements simultaneously perform the light emitting operation.
[0049]
On the other hand, in the light receiving device 33, the light receiving control circuit 17 outputs the amplified light receiving signal output from the light receiving element 33a and the amplified light receiving signal output from the light receiving element 33f, and the amplified light receiving signal output from the light receiving element 33c. The light receiving signal and the light receiving signal output from the light receiving element 33h and amplified, the light receiving signal output and amplified from the light receiving element 33e, the light receiving signal output and amplified from the light receiving element 33j, and the light output and amplified from the light receiving element 33b The received light signal, the amplified light signal output from the light receiving element 33g, and the amplified light receiving signal output from the light receiving element 33d, and the two light receiving signals output from the light receiving element 33i and amplified. The amplified light receiving signals output from the light receiving elements are simultaneously input (see (b) to (f) in FIG. 6).
[0050]
Accordingly, the light receiving signal output from the light receiving element 33a and the light receiving signal output from the light receiving element 33f, the light receiving signal output from the light receiving element 33c, the light receiving signal output from the light receiving element 33h, and the light receiving signal output from the light receiving element 33e. The light receiving signal and the light receiving signal output from the light receiving element 33j, the light receiving signal output from the light receiving element 33b and the light receiving signal output from the light receiving element 33g, the light receiving signal output from the light receiving element 33d and the light receiving output from the light receiving element 33i By sequentially comparing the signal level of the light receiving signal with the threshold value, it is detected whether or not the detection target is present (see (g) to (k) in FIG. 6).
[0051]
As described above, according to the third embodiment, in the multi-optical axis photoelectric switch 31, two non-adjacent ones of the ten light emitting elements 32a to 32j in the process of performing one scanning operation. Since the optical elements are configured to perform the light projecting operation continuously, the above-mentioned arrangement is reduced by reducing the arrangement pitch of the light projection elements 32a to 32j in the light projector 32 and the arrangement pitch of the light receiving elements 33a to 33j in the light receiver 33. In a manner similar to that described in the first embodiment, it is possible to detect whether or not a smaller detection target exists.
[0052]
In this case, since the two light emitting elements are configured to perform the light emitting operation at the same time, the two light emitting elements 32a to 32j each have two light emitting elements, compared to the configuration in which each of the light emitting elements 32a to 32j performs the light emitting operation. The time required for performing the scanning operation can be reduced by the amount of the simultaneous light emitting operation of the elements, and the response speed can be improved.
[0053]
(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIGS. The description of the same parts as in the second embodiment is omitted, and different parts will be described. The fourth embodiment is applied to a multi-optical axis photoelectric switch having eight optical axes.
[0054]
In the light projector 42, the light projecting elements 42a to 42h are divided into a set of light projecting elements 42a to 42d and a set of light projecting elements 42e to 42h, and the light projecting element 42b, the light projecting element 42f, and the light projecting element In the order of the light projecting element 42d and the light projecting element 42h, the light projecting element 42a and the light projecting element 42e, and the light projecting element 42c and the light projecting element 42g, the two light projecting elements simultaneously perform the light projecting operation sequentially ((a )reference). In this case, the light emitting element 42b and the light emitting element 42f, the light emitting element 42d and the light emitting element 42h, the light emitting element 42a and the light emitting element 42e, and the light emitting element 42c and the light emitting element 42g are sufficiently spaced from each other. Therefore, even if the two light emitting elements perform the light emitting operation at the same time, no interference occurs.
[0055]
On the other hand, in the light receiving device 43, the light receiving control circuit 17 outputs the amplified light receiving signal output from the light receiving element 43b and the amplified light receiving signal output from the light receiving element 43f, and the amplified light receiving signal output from the light receiving element 43d. The light receiving signal and the light receiving signal output and amplified from the light receiving element 43h, the light receiving signal output and amplified from the light receiving element 43a and the light receiving signal output and amplified from the light receiving element 43e, and the light output and amplified from the light receiving element 43c In accordance with the order of the received light signal and the amplified light signal output from the light receiving element 43g, the light signals output and amplified from the two light receiving elements are simultaneously input ((b) to (e) in FIG. 8). reference).
[0056]
Thereby, the light receiving signal outputted from the light receiving element 43b and the light receiving signal outputted from the light receiving element 43f, the light receiving signal outputted from the light receiving element 43d and the light receiving signal outputted from the light receiving element 43h, and the light receiving signal outputted from the light receiving element 43a The signal level of the light receiving signal and the light receiving signal output from the light receiving element 43e, the light receiving signal output from the light receiving element 43c, and the signal level of the light receiving signal output from the light receiving element 43g are sequentially compared with the threshold value. It is detected whether or not it exists (see (f) to (i) in FIG. 8).
[0057]
Then, also in this case, the light emitter 42 and the light receiver 43 perform the next scanning operation after a predetermined standby time (tc in FIG. 8) has elapsed after completing one scanning operation. Also in this case, during the predetermined standby time, the light receiving signals output from the light receiving elements 43b and 43f at the beginning of the scanning operation are emitted from the light emitting elements 42c and 42g that have performed the light emitting operation at the end of the immediately preceding scanning operation. It is a time that is not affected by light. Also in this case, the predetermined standby time can be effectively utilized by using the predetermined time as the time for the light receiving control circuit 17 to process the light receiving signal.
[0058]
As described above, according to the fourth embodiment, in the multi-optical axis photoelectric switch 41, in the process of performing one scanning operation, two non-adjacent ones of the eight light projecting elements 42a to 42h. In the process in which the light elements continuously perform the light emitting operation and the scanning operation is continuously performed, two adjacent light emitting elements among the eight light emitting elements 42a to 42h receive light at the beginning of the scanning operation. The light emitting operation is continuously performed so that the light receiving signals output from the elements 43b and 43f are not affected by the light emitted from the light emitting elements 42c and 42g that have performed the light emitting operation at the end of the immediately preceding scanning operation. With such a configuration, the arrangement pitch of the light projecting elements 42a to 42h in the light projector 42 and the arrangement pitch of the light receiving elements 43a to 43h in the light receiver 43 are narrowed, so that the arrangement described in the second embodiment described above is achieved. In the like, it can be detected whether the difference is less than the detection object exists.
[0059]
Also in this case, since the two light emitting elements are configured to perform the light emitting operation at the same time, the two light emitting elements 42a to 42h each have two light emitting elements compared to the configuration in which each of the light emitting elements 42a to 42h performs the light emitting operation. The time required for performing the scanning operation can be reduced by the amount of the simultaneous light emitting operation of the elements, and the response speed can be improved.
[0060]
(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIG. The description of the same parts as in the first embodiment will be omitted, and different parts will be described. The fifth embodiment has the same configuration as that of the first embodiment described above, but in the light projector 12, a light projecting element 12b, a light projecting element 12c, a light projecting element 12d, a light projecting element 12e, and a light projecting element. The light emitting operation is sequentially performed according to the order of 12a (see (a) in FIG. 9).
[0061]
On the other hand, in the light receiving device 13, the light receiving control circuit 17 outputs the amplified light receiving signal output from the light receiving element 13b, the amplified light receiving signal output from the light receiving element 13c, and the amplified light receiving signal output from the light receiving element 13d. Light receiving signals are input in the order of the light receiving signal, the light receiving signal output from light receiving element 13e and amplified, and the light receiving signal output and amplified from light receiving element 13a (see (b) to (e) in FIG. 9). .
[0062]
In this case, the operation interval (see te in FIG. 9) of the light projecting operation between the light projecting element 12e and the light projecting element 12a is such that the light projecting element 12b is not adjacent to the light projecting element 12b. The operation interval of the light projecting operation between the light projecting element 12c and the light projecting element 12c, the operation interval of the light projecting operation between the light projecting element 12c and the light projecting element 12d, and the light projecting operation between the light projecting element 12d and the light projecting element 12e. It can be set smaller than the operation interval of the light operation (see td in FIG. 9), and accordingly, the operation interval of all the light projection operations of the light emitting elements 12a to 12e is uniformly equal to the time corresponding to td in FIG. The response speed can be improved as compared with the case of setting to.
[0063]
(Other Examples)
The present invention is not limited to the above-described embodiment, but can be modified or expanded as follows.
In each embodiment, the order in which the light emitting elements perform the light emitting operation is such that a light receiving signal output from one light receiving element is emitted from another light emitting element except one light emitting element corresponding to one light receiving element. Any other order may be used as long as it satisfies the condition that it is not affected by the applied light.
[0064]
In the first embodiment, the number of light projecting elements and light receiving elements may be six or more, and in the second embodiment, the number of light projecting elements and light receiving elements may be five or more. In the third embodiment, the number of light projecting elements and light receiving elements may be 11 or more, and three or more light projecting elements may simultaneously perform a light projecting operation. In the fourth embodiment, the number of light projecting elements and light receiving elements may be nine or more, or a structure in which three or more light projecting elements simultaneously perform a light projecting operation.
[0065]
【The invention's effect】
As is clear from the above description, according to the multi-optical axis photoelectric switch of the present invention, the light receiving signal output from one light receiving means is related to the plurality of light emitting means in the course of performing one scanning operation. Except for one light emitting means corresponding to one light receiving means, a light emitting operation is performed continuously so as not to be affected by light emitted from other light emitting means. By narrowing the arrangement pitch of the means and the arrangement pitch of the light receiving means in the light receiver, it is possible to detect whether or not a smaller object to be detected exists, and furthermore, the operation of the light emitting operation of the light emitting means Since it is not necessary to set a large interval, it is possible to avoid a slow response speed.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing a first embodiment of the present invention.
FIG. 2 is a timing chart.
FIG. 3 is a functional block diagram showing a second embodiment of the present invention.
FIG. 4 is a diagram corresponding to FIG. 2;
FIG. 5 is a functional block diagram showing a third embodiment of the present invention.
FIG. 6 is a diagram corresponding to FIG. 2;
FIG. 7 is a functional block diagram showing a fourth embodiment of the present invention.
FIG. 8 is a diagram corresponding to FIG. 2;
FIG. 9 is a timing chart showing a fifth embodiment of the present invention.
FIG. 10 is a diagram showing an example of the related art.
FIG. 11 is a diagram corresponding to FIG. 2;
FIG. 12 is a diagram showing another example of the related art.
FIG. 13 is a diagram corresponding to FIG. 2;
[Explanation of symbols]
In the drawings, 11 is a multi-optical axis photoelectric switch, 12 is a light projector, 12a to 12e are light emitting elements (light emitting means), 13 is a light receiver, 13a to 13e are light receiving elements (light receiving means), and 17 is a light receiving control circuit. (Control means), 18a to 18e are amplification circuits (amplification means), 21 is a multi-optical axis photoelectric switch, 22 is a light projector, 22a to 22d are light projection elements (light projection means), 23 is a light receiver, and 23a to 23d Light receiving element (light receiving means), 31 is a multi-optical axis photoelectric switch, 32 is a light emitting element, 32a to 32j are light emitting elements (light emitting means), 33 is a light receiving element, 33a to 33j are light receiving elements (light receiving means), 41 is A multi-optical axis photoelectric switch, 42 is a light emitter, 42a to 42h are light emitting elements (light emitting means), 43 is a light receiver, and 43a to 43h are light receiving elements (light receiving means).

Claims

A plurality of light emitting means arranged substantially in a row in the light emitter, each of which sequentially performs light emitting operation,
A plurality of light receiving means arranged substantially in a line in a light receiver so as to correspond to the plurality of light emitting means on a one-to-one basis, each of which outputs a light receiving signal;
Amplifying means for amplifying a light receiving signal output from each of the plurality of light receiving means,
A signal level corresponding to the amount of received light of the received light signal output from each of the plurality of light receiving means and amplified by the amplifying means is compared with a threshold value in synchronization with the light emitting operation of each of the plurality of light emitting means. Control means for detecting whether an object to be detected exists or not,
In the multi-optical axis photoelectric switch which performs a scanning operation by the plurality of light emitting means performing a series of light emitting operations,
In the process of performing one scanning operation, the plurality of light emitting units exclude one light emitting unit corresponding to the one light receiving unit when a light receiving signal output from at least one or more one light receiving unit. A multi-optical axis photoelectric switch which performs a light emitting operation continuously so as not to be affected by light emitted from another light emitting means.

In the process of performing one scan operation, the plurality of light emitting units receive light signals output from all one of the light receiving units except for the one light emitting unit corresponding to the one light receiving unit. 2. The multi-optical axis photoelectric switch according to claim 1, wherein the light emitting operation is continuously performed so as not to be affected by the light emitted from the light means.

In the process of continuously performing the scanning operation, the adjacent two light emitting units of the plurality of light emitting units receive a light receiving signal output from the light receiving unit at the beginning of the scanning operation at the end of the immediately preceding scanning operation 3. The multi-optical axis photoelectric switch according to claim 1, wherein the light emitting operation is continuously performed so as not to be affected by the light emitted from the light emitting means that has performed the light emitting operation.

At least two or more of the plurality of light emitting means perform a light emitting operation at the same time as the one light emitting means corresponding to the one light receiving means when a light receiving signal output from one light receiving means is provided. 4. The multi-optical axis photoelectric switch according to claim 1, wherein a light emitting operation is performed simultaneously so as not to be affected by light emitted from other light emitting means.