JP2005071657A

JP2005071657A - Multiple optical-axis photoelectric sensor

Info

Publication number: JP2005071657A
Application number: JP2003209299A
Authority: JP
Inventors: Toru Wake; 徹和氣
Original assignee: Sunx Ltd
Current assignee: Panasonic Industrial Devices SUNX Co Ltd
Priority date: 2003-08-28
Filing date: 2003-08-28
Publication date: 2005-03-17

Abstract

PROBLEM TO BE SOLVED: To provide a multiple optical-axis photoelectric sensor capable of accurately adjusting optical axes even if an object other than one to be detected exists. SOLUTION: When a high-level signal of a clock-pulse signal is detected (at a step S2 'Y'), a photoreceptive signal from a photoreceptive element 21 of a first optical axis is validated and its photoreception volume level is read at a step S3, and it can be recognized whether the photoreceptive volume level at the photoreceptive element of the first optical axis is more than a threshold value V2 for optical axis assignment, on the basis of an output signal from a second comparator 29. Such a process is executed in turn up to a 24th optical axis, a minimum photoreception volume level is extracted from among ones exceeding the threshold value V2 at a step S6, and display of an optical axis adjustment display part 30 is controlled by a display pattern in accordance with the minimum photoreception volume level. COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、多光軸光電センサに関し、特に、光軸調整に関する。
【０００２】
【従来の技術】
この種の多光軸光電センサは、例えば一列状に配された複数の投光素子が設けられた投光器と、この投光器と対向配置され、上記複数の投光素子それぞれと対をなして光軸を形成し一列状に配された複数の受光素子が設けられた受光器とを備えて構成されている。そして、投光器の投光素子を順次投光動作させ、各投光素子の投光動作に同期して対応する受光素子から出力される受光信号を順次有効化させ、これらの受光信号レベルと検出用閾値との大小比較に基づき各光軸の入光／遮光を判定し、この判定結果に基づき投光器及び受光器間に介在する被検出物体の検出を行うようになっている。ところで、このような検出を実現するには、各光軸を形成する投光素子と受光素子とが正規に対向するように光軸調整を行う必要がある。
【０００３】
そこで、下記特許文献１及び２には、光軸調整を容易に行うための構成が開示されている。具体的には、特許文献１の構成は、光軸調整作業中において、前記光軸について投受光動作を実行し、全光軸数に対し、入光と判定された光軸の数の割合を表示手段に表示するようになっている。また、特許文献２の構成は、全光軸のうち受光量が最小レベルである光軸の受光量レベルを表示手段に表示するようになっている。これらの構成であれば表示手段の表示を視認しながら光軸調整を効率的に行うことができる。
【０００４】
【特許文献１】
特開平１１−３４５５４８号公報
【特許文献２】
特開２００２−１２４１６８公報
【０００５】
【発明が解決しようとする課題】
ところが、多光軸光電センサは、例えば固定の作業台を挟んで投光器及び受光器を配置するなど、常に一部の光軸が遮光物体によって遮光した状態で使用される場合がある。このような状態で使用される場合にも勿論光軸調整が必要となるわけであるが、上記特許文献１の構成は、全光軸に対する入光光軸の光軸数割合を表示する構成でなので、遮光物体によって遮光した光軸数を加味して表示手段の表示を見る必要があり不便である。
また、上記特許文献２の構成は、全光軸のうち最小レベルの光軸の受光量を表示する構成であるが、この構成では、上記遮光物体により常時遮光される光軸での受光量が表示されることとなり、光軸調整作業において表示手段の表示が変わらず表示手段の表示に基づいて光軸調整が行えないというおそれがある。
【０００６】
本発明は、上記事情に鑑みてなされたもので、その目的は、被検出物体以外の物体が存在しても正確に光軸調整を行うことが可能な多光軸光電センサを提供するところにある。
【０００７】
【課題を解決するための手段】
上記目的を達成するため、請求項１の発明に係る多光軸光電センサは、複数の投光素子と、複数の投光素子それぞれと対をなして光軸を形成する複数の受光素子と、複数の投光素子に順次投光動作をさせる投光制御手段と、各投光素子の投光動作に同期してそれに対応する受光素子から出力される受光量に応じた受光信号を有効化させる受光動作を行う受光制御手段と、受光制御手段にて有効化された受光信号を受けて、その受光量レベルと検出用閾値とを比較し、その比較結果に基づき各光軸が入光か遮光かを判定する判定手段と、判定手段による判定動作を無効化する光軸を指定する光軸指定手段と、光軸指定手段により指定された光軸の判定手段による判定動作を無効化する無効化手段と、無効化手段により無効化されない有効光軸の判定手段での判定結果に基づき被検出物体の検出動作を行う検出手段とを備えた多光軸光電センサであって、表示手段と、有効光軸を形成する受光素子からの受光信号に基づく表示パターンを表示手段に表示させる表示制御手段とを備えているところに特徴を有する。
【０００８】
請求項２の発明は、請求項１に記載の多光軸光電センサにおいて、受光制御手段にて有効化された受光信号を受けて、その受光量レベルを、検出用閾値以下でかつ光軸に物体が介在した状態での受光量レベルよりも高い光軸指定用閾値と比較する第１比較手段を備えて、光軸指定手段は、第１比較手段にて光軸指定用閾値以下の受光量レベルと判断された光軸を、無効化する光軸として指定するところに特徴を有する。
【０００９】
請求項３の発明は、請求項１記載の多光軸光電センサにおいて、外部から光軸を指定するための入力手段を備えて、光軸指定手段は、入力手段に入力された光軸に基づいて無効化すべき光軸を指定するところに特徴を有する。
【００１０】
請求項４の発明は、請求項１ないし請求項３のいずれかに記載の多光軸光電センサにおいて、外部からの制御信号を入力する制御信号入力手段を備えて、光軸指定手段は、制御信号入力手段に制御信号が入力されたことに基づいて所定期間無効化すべき光軸を指定するところに特徴を有する。
ここで、「制御信号」には、例えば被検出物体以外の物体が光軸内に侵入してくる場合、その侵入タイミングに同期して外部機器から与えられる信号（定期的に与えられる信号であっても不定期に与えられる信号であってもよい）や、作業者が入力設定部にて手動で行う入力動作に同期して与えられる信号などが含まれる。
【００１１】
請求項５の発明は、請求項１または請求項２に記載の多光軸光電センサにおいて、光軸数を設定する光軸数設定手段が備えられ、光軸指定手段は、光軸数設定手段にて設定れた光軸数に相当する光軸を無効化すべき光軸として指定するところに特徴を有する。
【００１２】
請求項６の発明は、請求項１ないし請求項５のいずれかに記載の多光軸光電センサにおいて、有効光軸を形成する受光素子からの受光信号に基づきその最小受光量を抽出する抽出手段が設けられ、表示制御手段は、抽出手段にて抽出された最小受光量レベルに応じた表示パターンを表示手段に表示させるところに特徴を有する。
【００１３】
請求項７の発明は、請求項１ないし請求項５のいずれかに記載の多光軸光電センサにおいて、受光制御手段にて有効化された受光信号の受光量レベルと、光軸に物体が介在した状態での受光量レベルよりも高い表示用閾値とを比較する第２比較手段が設けられ、表示制御手段は、有効光軸の数と、第２比較手段にて表示用閾値以上の受光量レベルと判断された光軸の数との相対量に応じた表示パターンを表示手段に表示させるところに特徴を有する。
【００１４】
請求項８の発明は、請求項６のいずれかに記載の多光軸光電センサにおいて、表示制御手段は、最小受光量レベルと、光軸に物体が介在した状態での受光量レベルよりも高い表示用閾値との相対量に応じた表示パターンを表示手段に表示させるところに特徴を有する。
【００１５】
請求項９の発明は、請求項７または請求項８記載の多光軸光電センサにおいて、表示用閾値は、検出用閾値と同レベルであるところに特徴を有する。
【００１６】
請求項１０の発明は、請求項１ないし請求項９のいずれかに記載の多光軸光電センサにおいて、表示手段は、バーグラフ表示手段で構成され、表示パターンをバーグラフ表示するところに特徴を有する。
【００１７】
【発明の作用及び効果】
＜請求項１の発明＞
本構成によれば、表示手段には、有効光軸（光軸指定手段にて指定されず判定手段による判定動作が無効化されない光軸）の受光素子から出力される、受光量に応じた受光信号に基づく表示パターンが表示される。従って、例えば被検出物体以外の物体が介在する光軸を予め無効化すべき光軸として指定することにより、この物体による影響を排除した表示パターンを表示手段に表示させることができ、光軸調整を正確に行うことができる。
【００１８】
＜請求項２の発明＞
本構成によれば、第１比較手段にて光軸指定用閾値（上記検出用閾値以下でかつ光軸に被検出物体以外の物体が介在した状態での受光量レベルよりも高いレベル。より好ましくは、検出用閾値より低くかつ光軸に被検出物体以外の物体が介在した状態での受光量レベルよりも高いレベル。）以下の受光量レベルを示す受光信号を出力した光軸が無効化する光軸とされ、これ以外の有効光軸の受光素子からの受光信号に基づく表示パターンが表示手段に表示される。
【００１９】
このような構成であれば、被検出物体以外の物体を挟んだ状態で多光軸光電センサを配置し、各光軸について投受光させることで上記物体が介在する光軸を自動で検知し、それを除いた有効光軸からの受光信号に基づく表示パターンを正確に表示することができる。
【００２０】
＜請求項３の発明＞
本構成によれば、例えば作業者が光軸を指定できる入力手段が設けられている。従って、被検出物体以外の物体が介在する光軸が予め分かっているときには、作業者の入力操作によって、例えば入力手段にて入力された光軸を無効化すべき光軸と指定したり、或いは、入力手段にて入力された光軸以外の無効化すべき光軸として指定したりして、排除すべき光軸を除いた有効光軸からの受光信号に基づく表示パターンを表示手段に表示させることができる。
【００２１】
なお、請求項１ないし請求項３のいずれかに記載の多光軸光電センサにおいて、無効化手段は、常時、前記光軸指定手段により指定された光軸の前記判定手段による判定動作を無効化する構成としてもよい。
本構成によれば、検出手段は、常時、有効光軸（光軸指定手段にて指定されず無効化されなかった光軸）の受光量レベルと検出用閾値とによる判定手段での判定結果に基づき被検出物体の検出動作を行う。従って、被検出物体以外の固定物体の存在が、一部の光軸に常時介在する場合であっても、その一部の光軸を除いた光軸（有効光軸）からの受光信号に基づき被検出物体の検出を行うことができる。つまり、本構成の多光軸光電センサは、いわゆるフィックスブランキング機能を備えているのである。特に、請求項２の構成を備えたものであれば、上記一部の光軸を自動で設定することができ、フィックスブランキング機能の設定を容易に行うことができる。
【００２２】
＜請求項４の発明＞
例えば、被検出物体以外の物体が定期的、或いは不定期的に光軸に介在する場合がある。そこで、本構成によれば、無効化手段は、制御信号入力手段に制御信号が入力されたことに基づいて、光軸指定手段により指定された光軸の判定手段による判定動作を所定期間だけ無効化するよう動作する。従って、例えば被検出物体以外の物体が定期的に光軸内に侵入する場合には、その侵入タイミングで制御信号を受けるよう構成し、常には、全光軸からの受光信号に基づき検出動作を行う一方で、上記制御信号を受けたときには所定期間、光軸指定手段にて指定された光軸を除く有効光軸からの受光信号に基づき検出動作を行うことが可能となる。つまり、本構成の多光軸光電センサは、いわゆるミューティング機能を備えているのである。
【００２３】
＜請求項５の発明＞
被検出物体以外の物体が移動する場合、その物体が介在する光軸も変わる。そこで、本構成によれば、光軸数を設定する光軸数設定手段が備えられ、光軸指定手段は、光軸数設定手段にて設定れた光軸数に相当する光軸だけを無効化すべき光軸として指定する。つまり、上記物体に加えて被検出物体が光軸に介在し上記光軸数設定手段にて設定された光軸数が遮光と判断されたときに初めて被検出物体ありの検出動作を行う。これにより、被検出物体以外の物体の介在位置が変動する場合であっても、被検出物体の検出を行うことができる。つまり、本構成の多光軸光電センサは、いわゆるフローティングブランキング機能を備えているのである。
【００２４】
＜請求項６の発明＞
本構成によれば、表示手段には、有効光軸のうち最小受光量レベルに応じた表示パターンが表示される。従って、表示手段の表示が、より高い受光量レベルに対応した表示パターンになるよう多光軸光電センサを動かすことで、被検出物体以外の物体による影響を受けることなく、容易に光軸調整を行うことができる。
【００２５】
＜請求項７の発明＞
表示手段には、受光制御手段にて有効化された受光信号の受光量レベルと、光軸に物体が介在した状態での受光量レベルよりも高い表示用閾値（検出用閾値または光軸指定用閾値と同レベルであっても異なるレベルであってもよい）とを比較する比較手段が設けられ、有効光軸の数と、表示用閾値以上の受光量レベルであった光軸の数との相対量（両者の比である相対値含む）に応じた表示パターンが表示される。従って、表示手段に表示された相対量に基づき有効光軸の数に対し、所定レベル以上の受光量レベルである光軸の数の割合が分かり、被検出物体以外の物体による影響を受けることなく、容易に光軸調整を行うことができる。
【００２６】
＜請求項８の発明＞
本構成によれば、表示手段には、上記最小受光量レベルと、前記光軸に物体が介在した状態での受光量レベルよりも高い表示用閾値（検出用閾値または光軸指定用閾値と同レベルであっても異なるレベルであってもよい）との相対量（両者の比である相対値含む）に応じた表示パターンが表示される。従って、最小受光量の受光信号レベルが表示用閾値等を上回るような表示パターンを表示手段に表示させるよう多光軸光電センサを動かすことで、全ての有効光軸について被検出物体の検出が可能な安定状態に光軸調整を行うことができる。
＜請求項９の発明＞
本構成によれば、上記表示用閾値は、検出用閾値と同レベルである。従って、表示手段の表示パターンに基づき検出用閾値以上の受光量レベルに光軸調整を行うことができる。
【００２７】
＜請求項１０の発明＞
本構成によれば、表示手段は、バーグラフ表示手段で構成され、各表示パターンがバーグラフで表示されるから、作業者は光軸の調整度合を視覚的に把握することができ、光軸調整作業がより容易になる。
【００２８】
【発明の実施の形態】
＜第１実施形態＞
以下、本発明の第１実施形態を図１〜図５に基づいて説明する。
１．本実施形態の多光軸光電センサの構成
（１）外観構成
本実施形態の多光軸光電センサは、図１に示すように、互いに対向配置される投光器１０と受光器２０とからなる。これら投受光器１０，２０は、共に、例えば上下に延びた角柱状をなし、投光器１０のうち受光器２０との対向面には、複数の投光素子１１が上下方向に沿って一列に配され、受光器２０のうち投光器１０との対向面には、前記各投光素子１１と対をなして光軸を形成する複数の受光素子２１が、やはり上下方向に沿って一列に配されている。
【００２９】
また、これら投受光素子１１，２１は、共に例えば２４個ずつ備えられており、上下方向で同じ順位に配置された投受光端子１１，２１同士が、互いに正規の相手方になっている。そして、後に詳説するように、各受光素子２１が光を受光して出力する受光信号（受けた光の受光量に応じた信号）は、正規の相手方投光素子１１からの光を受光したときにのみ、受光回路２２に受信される。
また、投光器１０及び受光器２０は、図１に示すように作業台Ｗ１（被検出物体以外の物体）を挟んで対向配置され、一部の光軸が常時遮光状態となる。
【００３０】
受光器２０の側面上部には、動作表示部２６が設けられている。この動作表示部２６は、例えば、表示灯としてのＬＥＤからなる。そして、その動作表示部２６の下方には、本発明の「表示手段」に相当する光軸調整用表示部３０が設けられている。この光軸調整用表示部３０は、例えば、４つの表示灯から構成され、各表示灯はＬＥＤからなる。なお、これら４つの表示灯同士を区別する場合には、上側の表示灯から順に、第１表示灯３１、第２表示灯３２、第３表示灯３３、第４表示灯３４ということにする。
【００３１】
（２）電気的構成
（ｉ）投光器
図２には、本実施形態の多光軸光電スイッチに係る電気的構成が示されている。同図に示すように、投光器１０には、前記投光素子１１が連なる投光回路１４（本発明の「投光制御手段」に相当）が設けられており、この投光回路１４は、所定のクロックパルス信号に基づいて作動し、投光器１０の上端側の投光素子１１から下端側の投光素子１１へと順次に駆動信号を与え、この動作を高周期で繰り返す。これにより、投光器１０の上端側の投光素子１１から順次に光信号が出射される。
【００３２】
（ｉｉ）受光器
一方、受光器２０には、前記受光素子２１が連なる受光回路２２（本発明の「受光制御手段」に相当）が設けられている。受光回路２２には、複数のスイッチ素子２５が備えられ、これらスイッチ素子２５の一方のリード部に、各受光素子２１の出力端子を接続すると共に、他方のリード部を、受光側ＣＰＵ２４の入力端子に共通接続してある。
【００３３】
また、各スイッチ素子２５に備えた制御用端子２５Ａは、シフトレジスタ２３を介して受光側ＣＰＵ２４の出力端子に接続されている。そして、各スイッチ素子２５は、常には、オフ状態になっており、受光側ＣＰＵ２４からシフトレジスタ２３を介して各スイッチ素子２５に駆動信号が順次に与えられ、これによりオンしたスイッチ素子２５に連なる受光素子２１の受光信号だけが、受光側ＣＰＵ２４に取り込まれるようになっている。
【００３４】
さらに、受光側ＣＰＵ２４は、投受光器１０，２０を繋ぐラインＬ１を介して、投光回路１４から前記クロックパルス信号を取り込んでおり、このクロックパルス信号（即ち、各投光素子１１の投光タイミング）に同期して、所定のスイッチ素子２５をオンさせる。具体的には、上下一列に配された投光素子１１のうち所定順位の投光素子１１が光信号を投光した瞬間に、その投光素子１１と同順位に配された受光素子２１に連なるスイッチ素子２５のみをオンする。これにより、各受光素子２１が、正規の相手方投光素子１１からの光を受光したときにのみ、その受光素子２１が出力した受光信号が受光側ＣＰＵ２４に取り込まれる。
【００３５】
また、各受光素子２１から順次有効化された受光信号は、第１コンパレータ２８及び第２コンパレータ２９の入力にもそれぞれ与えられ、第１コンパレータ２８及び第２コンパレータ２９の出力が受光側ＣＰＵ２４に与えられるようになっている。このうち第１コンパレータ２８は、本発明の「判定手段」に相当し、ここには、各光軸が入光状態か遮光状態かを判別するための検出用閾値Ｖ１が設定されている。この検出用閾値Ｖ１は、例えば正規の相手方となる投光素子１１及び受光素子２１の間に物体がある場合とない場合での受光素子２１からの受光信号レベルの間のレベルに設定されている。一方、第２コンパレータ２９は、本発明の「比較手段」に相当し、ここには、上記検出用閾値Ｖ１よりも低く、かつ、上記作業台Ｗ１が介在する光軸の受光素子２１から出力される受光信号レベルより高いレベルの光軸指定用閾値Ｖ２が設定されている。
【００３６】
２．受光側ＣＰＵの制御動作
（１）光軸調整時
例えば投光器１０または受光器２０に設けられた図示しないモード切換スイッチを「光軸調整モード」に設定して起動させると、投光器１０はクロックパルス信号に同期して順次投光素子１１に投光動作をさせるととともに、上記クロックパルス信号を受光器２０側に与える。そして、このクロックパルス信号を受けると、受光側ＣＰＵ２４は図３の表示制御ルーチンに示すフローチャートを実行する。
【００３７】
まず、ステップＳ１で光軸番号Ｋを１に初期化し、クロックパルス信号のハイレベル信号を検知したら（ステップＳ２で「Ｙ」）、ステップＳ３で１番目の光軸（例えば図１及び図２において最上段の光軸）の受光素子２１からの受光信号を有効化させてその受光量レベルを読取る。それとともに、第２コンパレータ２９からの出力信号を読取る。ここで、受光側ＣＰＵ２４は第２コンパレータ２９からの出力信号に基づき、１番目の光軸の受光素子２１での受光量レベルが光軸指定用閾値Ｖ２以上かどうかを認識することができる。
【００３８】
そして、これらステップＳ２，Ｓ３の処理を２４番目の光軸（例えば図１及び図２において最下段の光軸）まで順次実行する（ステップＳ４，５）。そして、２４番目の光軸まで実行したら（ステップＳ４で「Ｙ」）、ステップＳ６において、光軸指定用閾値Ｖ２以上の受光量レベルの中から最小受光量レベルを抽出する。なお、光軸指定用閾値Ｖ２以上の受光量レベルを示す受光素子２１の光軸が本発明の「有効光軸」に相当する。
【００３９】
続いて、ステップＳ７で上記最小受光量レベルに応じた表示パターンで光軸調整用表示部３０の表示を制御する。具体的には、受光側ＣＰＵ２４は、検出用閾値Ｖ１に対する最小受光量レベルの相対値を算出し、その相対値に応じた表示パターンで光軸調整用表示部３０の表示を制御する。光軸調整用表示部３０は、図４に示すように、上下方向に配列された４つの表示灯からなるバーグラフ表示で構成されており、例えば、第１表示灯３１は相対値１２０％以上のときに、第２表示灯３２は相対値１１０〜１２０％のときに、第３表示灯３３は相対値１００〜１１０％のときに、第４表示灯３４は相対値１００％以下のときにそれぞれ点灯動作するよう制御される。
【００４０】
（２）具体的動作
例えば図５（Ａ）に示すように、投光器１０に対して受光器２０がやや傾いて配置された場合、下方側の光軸は略一致し投光素子１１からの光のほとんどはその相手方の受光素子２１に受光されるが、上方側に向かうに連れて光軸のずれ量は大きくなり、受光素子２１での受光量は徐々に小さくなる（同（Ｂ）の実線Ａ参照）。また、作業台Ｗ１が介在する光軸については受光量が略０になる。そうすると、受光側ＣＰＵ２４は、は、上述した表示制御ルーチンを実行し、全光軸について投受光動作を一巡させて各光軸に対応する受光量レベルと、第２コンパレータ２９からの出力信号を読取る（ステップＳ１〜Ｓ５）。この結果、作業台Ｗ１が介在する１１〜１４番目の光軸での受光量レベルは光軸指定用閾値Ｖ２を下回り、それ以外の光軸での受光量レベルが光軸指定用閾値Ｖ２を上回ることが認識され、１〜１０、１５〜２４番目の光軸が有効光軸と指定される。
【００４１】
そして、これらの有効光軸のうち最も光軸のずれ量が大きい１番目の光軸での受光量レベルが最小受光量として抽出される（ステップＳ６）。そして、この最小受光量の検出用閾値Ｖ１に対する相対値は例えば９０％であり、これにより光軸調整用表示部３０の第４表示灯３４のみが点灯する（ステップＳ７）。従って、作業者はこの光軸調整用表示部３０の表示パターンを見れば有効光軸のうち最も光軸ずれが大きい光軸での受光量レベルは検出用閾値Ｖ１に対して１００％以下であることを知ることができる。そして、光軸調整用表示部３０の第３表示灯３３も点灯させるように受光器２０を回動させる（図５（Ａ）で矢印方向））。そうすると上方側の光軸での受光量レベルも徐々に増加し（同図（Ｂ）で二点破線Ｂ参照）、更に移動させることで全ての有効光軸が一致し、受光量レベルが検出用閾値Ｖ１に対して１２０％以上の安定レベルとなり、被検出物体による入光・遮光を確実に検出可能な安定状態に光軸調整を行うことができる。
【００４２】
（３）検出動作時
光軸調整終了後に、上記モード切換スイッチを「検出モード」に切り換えると、上記クロックパルス信号に同期して全光軸について投受光動作を順次実行する。ここで、受光側ＣＰＵ２４は、上記表示制御ルーチン実行により有効光軸が１〜１０、１５〜２４番目の光軸であると認識しているから、その有効光軸の各投受光動作に同期して第１コンパレータ２８の出力信号を読取り、遮光を示す出力信号（第１コンパレータ２８で受光信号レベルが検出用閾値Ｖ１を下回ったときの出力信号）を受けたときに、上記動作表示部２６を点灯させるとともに、出力線２７を介して外部機器に検出信号を出力する。例えば、図１において、作業者の手（被検出物体に相当）などが投光器１０及び受光器２０間に侵入したときには、被検出物体が検出されたとして動作表示部２６が点灯動作をするのである。つまり、本実施形態の多光軸光電センサは、いわゆるフィックスブランキング機能を備えているのである。
【００４３】
３．本実施形態の効果
以上のように、本実施形態によれば、光軸調整用表示部３０には、作業台Ｗ１が介在する光軸を除いた有効光軸での受光量レベルのうち、最小受光量レベルに応じた表示パターンが表示される。従って、作業台Ｗ１などの被検出物体以外の物体が一部の光軸に介在する場合であっても、この物体による影響を排除した表示パターンを光軸調整用表示部３０に表示でき、光軸調整を正確に行うことができる。
【００４４】
また、光軸指定用閾値Ｖ２が設定された第２コンパレータ２９からの出力信号に基づき作業台Ｗ１が介在しない有効光軸の指定を自動で行うことができ、有効光軸を確実に指定して正確な表示パターンを光軸調整用表示部３０に表示させることができる（請求項２の構成）。
【００４５】
更に、有効光軸のうち最小受光量レベルと検出閾値との比である相対値に応じた表示パターンを光軸調整用表示部３０に表示させる構成であり、かつ、光軸調整用表示部３０は各表示パターンを第１〜４表示灯によるバーグラフ表示で行う構成なので、光軸調整度合を視覚的に把握しやすく容易に光軸調整を行うことができる（請求項６、８，１０の構成に相当）。
【００４６】
＜第２実施形態＞
第２実施形態は、請求項４の構成に相当する。前記実施形態との相違は、検出動作にあり、その他の点は前記第１実施形態と同様である。従って、第１実施形態と同一符号を付して重複する説明を省略し、異なるところのみを次に説明する。
【００４７】
例えば、固定の作業台Ｗ１ではなく、所定の周期毎に例えば１１〜１４番目の光軸を遮る移動物体（被検出物体以外の物体）が存在する場合がある。そこで、本実施形態では、予めその移動物体を介在させた状態で上記光軸調整モードを実行して有効光軸を特定し、検出動作時には、常には、全光軸（１〜２４番目）に対応する第１コンパレータ２８からの出力信号に基づき検出動作（全光軸検出動作）を行う一方で、移動物体の侵入タイミングに同期して出力される制御信号を受けたときには、所定時間の間、有効光軸（１〜１０、１５〜２４番目）に対応する第１コンパレータ２８からの出力信号に基づき検出動作（有効光軸検出動作）を行う。つまり、上記移動物体が侵入していないときには全光軸検出動作を行い、上記移動物体が侵入しているときには有効光軸検出動作を行うのである。つまり、本実施形態の多光軸光電センサは、いわゆるミューティング機能を備えている。
【００４８】
＜第３実施形態＞
図６は（請求項５の発明に対応する）第３実施形態を示す。前記実施形態との相違は、やはり検出動作にあり、その他の点は前記第１実施形態と同様である。従って、第１実施形態と同一符号を付して重複する説明を省略し、異なるところのみを次に説明する。
図６に示すように、作業者が角材Ｗ２（被検出物体以外の物体）を投光器１０及び受光器２０間に侵入させる場合がある。この場合、角材の侵入位置は不特定であるが、角材Ｗ２により遮られる光軸の数は一定である。
【００４９】
そこで、本実施形態では、この角材Ｗ２により遮られる光軸数を設定する図示しない光軸数設定手段（例えばコンソール）が設けられている。これは、例えば上記角材Ｗ２を投光器１０及び受光器２０間に侵入させた状態で全光軸について投受光動作を行うことで、受光側ＣＰＵ２４は受光量レベルが検出用閾値Ｖ１或いは光軸指定用閾値Ｖ２を下回った光軸の数（例えば３光軸）を認識することで設定される。そうすると、受光側ＣＰＵ２４は、受光量レベルが検出用閾値Ｖ１或いは光軸指定用閾値Ｖ２を下回った光軸の数が３光軸以下であればその全ての光軸に対応する第１コンパレータ２８からの出力信号は無視し、それ以外の光軸に対応する第１コンパレータ２８からの出力信号に基づき検出動作を行う。つまり、角材Ｗ２を侵入させただけでは被検出物体ありとの検出動作は行われない。
一方、受光量レベルが検出用閾値Ｖ１或いは光軸指定用閾値Ｖ２を下回った光軸の数が３光軸を超える場合には、そのうち３光軸に対応する第１コンパレータ２８からの出力信号だけが無視され、それ以外の光軸に対応する第１コンパレータ２８からの出力信号は有効なものとして検出動作に使用される。つまり、角材Ｗ２に加えて例えば作業者の手などが侵入したときに初めて被検出物体ありの検出動作が実行される。つまり、本実施形態の多光軸光電センサは、いわゆるフローティングブランキング機能を備えているのである。
【００５０】
＜他の実施形態＞
本発明は、前記実施形態に限定されるものではなく、例えば、以下に説明するような実施形態も本発明の技術的範囲に含まれ、さらに、下記以外にも要旨を逸脱しない範囲内で種々変更して実施することができる。
（１）上記各実施形態の光軸調整用表示部３０は、投光器１０側に設けた構成であってもよい。また、投光器１０または受光器２０に連なる専用器に設けた構成であってもよい。
【００５１】
（２）上記各実施形態において、最小受光量を示す光軸（例えば光軸番号や位置など）を報知する報知手段を更に設けた構成であってもよい。
【００５２】
（３）上記各実施形態において、第２コンパレータ２９の代わりに或いはそれに加えて、例えば外部から受光側ＣＰＵに光軸指定の指示信号を与える入力手段（例えばコンソール等）が設けられ、この入力操作によって指定された光軸、或いはそれ以外の光軸を有効光軸として、これらの有効光軸からの受光信号に基づき受光側ＣＰＵが上記表示制御や検出動作を行う構成であってもよい（請求項３の構成に相当）。具体的には、１１〜１４番目の光軸に作業台Ｗ１が常時介在することが分かっている場合には、入力手段にて１１〜１４番目の光軸を指定すると、それ以外の１〜１０、１５〜２４番目の光軸を有効光軸として上記表示制御や検出動作を行うのである。
【００５３】
（４）上記各実施形態では、判定手段及び比較手段を第１コンパレータ２８及び第２コンパレータ２９などのハードウエアで構成したが、これに限らず、受光側ＣＰＵ２４の処理によりソフトウエアで構成してもよい。
【００５４】
（５）検出用閾値Ｖ１と、光軸指定用閾値Ｖ２とは同レベルとしてもよい。この場合、第２コンパレータ２９を取り除いて、第１コンパレータ２８からの出力信号に基づき有効光軸を定める構成とすることができる。
【００５５】
（６）上記各実施形態では、全光軸について投受光動作を一巡させたときに各光軸での受光量レベルに基づき表示表示制御や検出動作を行う構成としたが、これに限らず、全光軸についての投受光動作を複数回繰り返し行った後に、その間に得られた受光信号に基づいて上記表示表示制御や検出動作を行う構成であってもよい。
【００５６】
（７）被検出物体以外の物体には、上記作業台Ｗ１のように完全遮光物体だけでなく、受けた光の一部を透過させる半透明物体や透明物体などであってもよい。この場合、光軸指定用閾値Ｖ２レベルは、上記物体（半透明物体や透明物体）を介在させた状態で投光素子１１からの光を受ける受光素子２１からの受光信号レベルより高く設定すればよい。
【００５７】
（８）上記各実施形態では、最小受光量と検出用閾値Ｖ１との比である相対値に応じたバーグラフ表示を行う構成としたが、最小受光量と光軸指定用閾値との比である相対値に応じたバーグラフ表示であってもよい。また、その相対値そのものを例えばデジタル表示器等によって数値表示する構成であってもよい。またバーグラフ表示に限らず、円グラフ表示であってもよい。更に、最小受光量と各閾値との比である相対値ではなく、両者のレベル差に応じた表示パターンであってもよい。また、表示灯の点灯タイミングや色などを変える表示パターンであってもよい。
【００５８】
（９）また、最小受光量と各閾値との比である相対値ではなく、有効光軸の数と、検出用閾値Ｖ１または光軸指定用閾値Ｖ２以上の受光量レベルであった光軸の数との相対量（両者の比である相対値や、両者のレベル差などを含む）に応じた表示パターンであってもよい（請求項７の構成に相当）。例えば図５（Ｂ）の実線Ａであれば、有効光軸数２０と、検出用閾値Ｖ１以上の光軸約９との比である相対値に応じた表示パターンを表示手段に表示（上記バーグラフ表示、円グラフ表示、数値表示、点灯タイミングや色の変更による表示など）するのである。
【図面の簡単な説明】
【図１】本発明の第１実施形態に係る多光軸光電センサの斜視図
【図２】電気的構成図
【図３】表示制御ルーチンを示すフローチャート
【図４】光軸調整用表示部の簡略図
【図５】各光軸のずれ量と、受光量レベルとの関係を示した説明図
【図６】第３実施形態に係る多光軸光電センサの斜視図
【符号の説明】
１１…投光素子
２１…受光素子
２２…受光回路
２３…シフトレジスタ
２４…受光側ＣＰＵ
２５…スイッチ素子
２６…動作表示部
２８…第１コンパレータ（判定手段）
２９…第２コンパレータ（比較手段）
３０…光軸調整用表示部（表示手段）
Ｖ１…検出用閾値
Ｖ２…光軸指定用閾値
Ｗ１…作業台
Ｗ２…角材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-optical axis photoelectric sensor, and more particularly to optical axis adjustment.
[0002]
[Prior art]
This type of multi-optical axis photoelectric sensor includes, for example, a projector provided with a plurality of light projecting elements arranged in a line, and an optical axis that is disposed opposite to the light projector and forms a pair with each of the plurality of light projecting elements. And a light receiver provided with a plurality of light receiving elements arranged in a line. Then, the light projecting elements of the projector are sequentially projected, and the light receiving signals output from the corresponding light receiving elements are sequentially validated in synchronization with the light projecting operations of the light projecting elements. Based on the comparison with the threshold value, light incident / light shielding of each optical axis is determined, and based on the determination result, an object to be detected interposed between the projector and the light receiver is detected. By the way, in order to realize such detection, it is necessary to adjust the optical axis so that the light projecting element and the light receiving element forming each optical axis are properly opposed to each other.
[0003]
Therefore, Patent Documents 1 and 2 below disclose configurations for easily performing optical axis adjustment. Specifically, in the configuration of Patent Document 1, during the optical axis adjustment work, a light projecting / receiving operation is executed for the optical axis, and the ratio of the number of optical axes determined to be incident to the total number of optical axes is calculated. It is displayed on the display means. Further, the configuration of Patent Document 2 is configured to display the received light amount level of the optical axis having the minimum received light amount among all the optical axes on the display means. With these configurations, the optical axis can be adjusted efficiently while visually recognizing the display on the display means.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-345548
[Patent Document 2]
JP 2002-124168 A
[0005]
[Problems to be solved by the invention]
However, the multi-optical axis photoelectric sensor may be used in a state where a part of the optical axis is always shielded by a light-shielding object, for example, a projector and a light receiver are arranged with a fixed workbench interposed therebetween. Of course, even when used in such a state, optical axis adjustment is necessary. However, the configuration of the above-mentioned Patent Document 1 is a configuration that displays the ratio of the number of optical axes of the incident optical axes to the total optical axes. Therefore, it is inconvenient because it is necessary to view the display of the display means in consideration of the number of optical axes shielded by the light shielding object.
In addition, the configuration of Patent Document 2 is a configuration that displays the amount of light received at the lowest level among all the optical axes, but in this configuration, the amount of light received at the optical axis that is always shielded by the light-shielding object. There is a risk that the display of the display means does not change during the optical axis adjustment operation, and the optical axis adjustment cannot be performed based on the display of the display means.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multi-optical axis photoelectric sensor capable of accurately performing optical axis adjustment even when an object other than an object to be detected exists. is there.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a multi-optical axis photoelectric sensor according to the invention of claim 1 includes a plurality of light projecting elements and a plurality of light receiving elements that form an optical axis in pairs with the plurality of light projecting elements, A light projecting control means for sequentially performing a light projecting operation to a plurality of light projecting elements, and a light receiving signal corresponding to the amount of light received from the corresponding light receiving element in synchronization with the light projecting operation of each light projecting element is validated. The light reception control means for performing the light reception operation and the light reception signal validated by the light reception control means are compared, and the light reception level and the detection threshold value are compared. Based on the comparison result, each optical axis is incident or blocked. Determining means for determining whether or not, an optical axis specifying means for specifying an optical axis for invalidating the determination operation by the determining means, and an invalidation for invalidating the determination operation by the determining means for the optical axis specified by the optical axis specifying means And an effective optical axis that is not invalidated by the invalidating means. A multi-optical axis photoelectric sensor comprising a detecting means for detecting an object to be detected based on a determination result by a fixing means, wherein the display is based on a light receiving signal from a light receiving element that forms an effective optical axis. It is characterized in that it includes display control means for displaying the pattern on the display means.
[0008]
According to a second aspect of the present invention, in the multi-optical axis photoelectric sensor according to the first aspect of the present invention, the light reception signal validated by the light reception control means is received, and the received light amount level is equal to or less than the detection threshold value and on the optical axis. First comparison means for comparing with an optical axis designating threshold value higher than the received light amount level in the state where the object is interposed is provided, and the optical axis designating means receives the received light amount equal to or less than the optical axis designating threshold value in the first comparing means. It is characterized in that the optical axis determined to be a level is designated as an optical axis to be invalidated.
[0009]
A third aspect of the invention is the multi-optical axis photoelectric sensor according to the first aspect, further comprising input means for designating the optical axis from the outside, wherein the optical axis designation means is based on the optical axis input to the input means. This is characterized by designating the optical axis to be invalidated.
[0010]
The invention of claim 4 is the multi-optical axis photoelectric sensor according to any one of claims 1 to 3, further comprising control signal input means for inputting a control signal from the outside, wherein the optical axis designating means is a control unit. It is characterized in that the optical axis to be invalidated for a predetermined period is designated based on the input of the control signal to the signal input means.
Here, for example, when an object other than the detected object enters the optical axis, the “control signal” is a signal (periodically given signal) given from an external device in synchronization with the entry timing. Or a signal given in an irregular manner), a signal given in synchronization with an input operation manually performed by an operator at the input setting unit, and the like.
[0011]
According to a fifth aspect of the present invention, in the multi-optical axis photoelectric sensor according to the first or second aspect, an optical axis number setting means for setting the number of optical axes is provided, and the optical axis designating means is the optical axis number setting means. This is characterized in that the optical axis corresponding to the number of optical axes set in is designated as the optical axis to be invalidated.
[0012]
According to a sixth aspect of the present invention, in the multi-optical axis photoelectric sensor according to any one of the first to fifth aspects, the extraction means extracts the minimum amount of light received based on the light reception signal from the light receiving element forming the effective optical axis. The display control means is characterized in that the display means displays a display pattern corresponding to the minimum received light amount level extracted by the extraction means.
[0013]
According to a seventh aspect of the present invention, in the multi-optical axis photoelectric sensor according to any one of the first to fifth aspects, the received light amount level of the received light signal enabled by the light receiving control means and an object interposed on the optical axis The second comparison means for comparing the display threshold value higher than the received light amount level in the state is provided, and the display control means receives the number of effective optical axes and the received light amount equal to or greater than the display threshold value by the second comparison means. It is characterized in that a display pattern corresponding to the relative amount of the level and the number of optical axes determined is displayed on the display means.
[0014]
The invention according to claim 8 is the multi-optical axis photoelectric sensor according to claim 6, wherein the display control means is higher than the minimum received light amount level and the received light amount level when an object is interposed on the optical axis. It is characterized in that a display pattern corresponding to a relative amount with respect to the display threshold is displayed on the display means.
[0015]
The invention of claim 9 is characterized in that, in the multi-optical axis photoelectric sensor of claim 7 or claim 8, the display threshold is the same level as the detection threshold.
[0016]
The invention of claim 10 is characterized in that, in the multi-optical axis photoelectric sensor according to any one of claims 1 to 9, the display means is constituted by a bar graph display means, and the display pattern is displayed as a bar graph. Have.
[0017]
[Action and effect of the invention]
<Invention of Claim 1>
According to this configuration, the display unit receives light according to the amount of received light that is output from the light receiving element of the effective optical axis (the optical axis that is not specified by the optical axis specifying unit and the determination operation by the determination unit is not invalidated). A display pattern based on the signal is displayed. Therefore, for example, by designating in advance the optical axis in which an object other than the detected object is present as the optical axis to be invalidated, a display pattern that eliminates the influence of this object can be displayed on the display means, and optical axis adjustment can be performed. Can be done accurately.
[0018]
<Invention of Claim 2>
According to this configuration, the first comparison means has a threshold value for optical axis designation (a level lower than the detection threshold value and higher than the received light amount level in the state where an object other than the detected object is interposed on the optical axis. More preferably. Is a level lower than the detection threshold and higher than the received light level when an object other than the detected object is interposed on the optical axis.) The optical axis that outputs the received light signal indicating the received light level below is invalidated. A display pattern based on the received light signal from the light receiving element of the other effective optical axis is displayed on the display means.
[0019]
With such a configuration, the multi-optical axis photoelectric sensor is arranged in a state where an object other than the object to be detected is sandwiched, and the optical axis in which the object is interposed is automatically detected by projecting and receiving each optical axis, The display pattern based on the received light signal from the effective optical axis except the above can be displayed accurately.
[0020]
<Invention of Claim 3>
According to this configuration, for example, the input means that allows the operator to specify the optical axis is provided. Therefore, when the optical axis on which an object other than the object to be detected is known in advance, for example, the optical axis input by the input means is designated as the optical axis to be invalidated by the operator's input operation, or The display means can display a display pattern based on the received light signal from the effective optical axis excluding the optical axis to be excluded, by designating it as an optical axis to be invalidated other than the optical axis input by the input means. it can.
[0021]
The multi-optical axis photoelectric sensor according to any one of claims 1 to 3, wherein the invalidating means always invalidates the determination operation by the determining means for the optical axis specified by the optical axis specifying means. It is good also as composition to do.
According to this configuration, the detection means always uses the determination result by the determination means based on the received light amount level of the effective optical axis (the optical axis not specified by the optical axis specifying means and not invalidated) and the detection threshold. Based on this, the detected object is detected. Therefore, even if the presence of a fixed object other than the object to be detected is always present in some optical axes, it is based on the received light signal from the optical axis (effective optical axis) excluding that optical axis. The detected object can be detected. That is, the multi-optical axis photoelectric sensor of this configuration has a so-called fixed blanking function. In particular, if it has the structure of Claim 2, the said one part optical axis can be set automatically, and the setting of a fixed blanking function can be performed easily.
[0022]
<Invention of Claim 4>
For example, an object other than the object to be detected may be present on the optical axis regularly or irregularly. Therefore, according to this configuration, the invalidating unit invalidates the determination operation by the optical axis determining unit designated by the optical axis designating unit for a predetermined period based on the input of the control signal to the control signal input unit. To work. Therefore, for example, when an object other than the object to be detected regularly enters the optical axis, it is configured to receive a control signal at the entry timing, and the detection operation is always performed based on the received light signals from all the optical axes. On the other hand, when the control signal is received, the detection operation can be performed for a predetermined period based on the light reception signal from the effective optical axis excluding the optical axis designated by the optical axis designation means. That is, the multi-optical axis photoelectric sensor of this configuration has a so-called muting function.
[0023]
<Invention of Claim 5>
When an object other than the detected object moves, the optical axis that the object intervenes also changes. Therefore, according to this configuration, the optical axis number setting means for setting the number of optical axes is provided, and the optical axis designating means invalidates only the optical axes corresponding to the optical axis number set by the optical axis number setting means. Specify as the optical axis to be converted. In other words, the detection operation with the detected object is performed only when the detected object is interposed in the optical axis in addition to the object and the number of optical axes set by the optical axis number setting means is determined to be shielded. Thereby, even when the intervening position of an object other than the detected object varies, the detected object can be detected. That is, the multi-optical axis photoelectric sensor of this configuration has a so-called floating blanking function.
[0024]
<Invention of Claim 6>
According to this configuration, the display unit displays a display pattern corresponding to the minimum received light amount level of the effective optical axis. Therefore, by moving the multi-optical axis photoelectric sensor so that the display means displays a display pattern corresponding to a higher received light amount level, the optical axis can be easily adjusted without being affected by objects other than the detected object. It can be carried out.
[0025]
<Invention of Claim 7>
The display means includes a received light amount level of the received light signal enabled by the received light control means and a display threshold value (detection threshold value or optical axis designation value) higher than the received light amount level when an object is interposed on the optical axis. A comparison means is provided, and the number of effective optical axes and the number of optical axes that have received light levels equal to or greater than the display threshold value are provided. A display pattern corresponding to the relative amount (including the relative value that is the ratio between the two) is displayed. Therefore, based on the relative amount displayed on the display means, the ratio of the number of optical axes having a light receiving amount level equal to or higher than a predetermined level to the number of effective optical axes can be known, and without being affected by an object other than the detected object. The optical axis can be adjusted easily.
[0026]
<Invention of Claim 8>
According to this configuration, the display means has the minimum received light amount level and a display threshold value higher than the received light amount level when an object is interposed on the optical axis (the detection threshold value or the optical axis designation threshold value). A display pattern corresponding to a relative amount (including a relative value that is a ratio of both) is displayed. Therefore, it is possible to detect the detected object for all effective optical axes by moving the multi-optical axis photoelectric sensor so that the display means displays a display pattern in which the light reception signal level of the minimum light reception amount exceeds the display threshold value etc. The optical axis can be adjusted to a stable state.
<Invention of Claim 9>
According to this configuration, the display threshold is at the same level as the detection threshold. Therefore, the optical axis can be adjusted to a received light amount level equal to or higher than the detection threshold based on the display pattern of the display means.
[0027]
<Invention of Claim 10>
According to this configuration, the display unit is configured by a bar graph display unit, and each display pattern is displayed as a bar graph. Therefore, the operator can visually grasp the adjustment degree of the optical axis, and the optical axis Adjustment work becomes easier.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
1. Configuration of multi-optical axis photoelectric sensor of this embodiment
(1) Appearance configuration
As shown in FIG. 1, the multi-optical axis photoelectric sensor of this embodiment includes a light projector 10 and a light receiver 20 that are arranged to face each other. Both of the light projecting / receiving devices 10 and 20 have, for example, a prismatic shape extending vertically, and a plurality of light projecting elements 11 are arranged in a line along the vertical direction on the surface of the light projecting device 10 facing the light receiving device 20. A plurality of light receiving elements 21 that form an optical axis in pairs with the light projecting elements 11 are arranged in a line along the vertical direction on the surface of the light receiver 20 that faces the light projector 10. Yes.
[0029]
In addition, for example, 24 light projecting / receiving elements 11 and 21 are provided, for example, and the light projecting / receiving terminals 11 and 21 arranged in the same order in the vertical direction are normal counterparts. As will be described in detail later, the light receiving signal (the signal corresponding to the amount of received light) received by each light receiving element 21 is received when the light from the normal counterpart light projecting element 11 is received. Is received by the light receiving circuit 22 only.
Further, as shown in FIG. 1, the light projector 10 and the light receiver 20 are arranged to face each other with a work table W1 (an object other than the object to be detected) interposed therebetween, and a part of the optical axis is always in a light shielding state.
[0030]
An operation display unit 26 is provided on the upper side of the light receiver 20. For example, the operation display unit 26 includes an LED as an indicator lamp. An optical axis adjustment display unit 30 corresponding to the “display unit” of the present invention is provided below the operation display unit 26. The display unit 30 for adjusting the optical axis is composed of, for example, four indicator lamps, and each indicator lamp is composed of LEDs. In order to distinguish these four indicator lamps, the first indicator lamp 31, the second indicator lamp 32, the third indicator lamp 33, and the fourth indicator lamp 34 will be referred to in order from the upper indicator lamp.
[0031]
(2) Electrical configuration
(I) Floodlight
FIG. 2 shows an electrical configuration according to the multi-optical axis photoelectric switch of the present embodiment. As shown in the figure, the projector 10 is provided with a projector circuit 14 (corresponding to the “projection control means” of the present invention) in which the projector elements 11 are connected. The driving signal is sequentially given from the light projecting element 11 on the upper end side to the light projecting element 11 on the lower end side, and this operation is repeated at a high cycle. Thereby, an optical signal is sequentially emitted from the light projecting element 11 on the upper end side of the projector 10.
[0032]
(Ii) Receiver
On the other hand, the light receiver 20 is provided with a light receiving circuit 22 (corresponding to the “light receiving control means” of the present invention) connected to the light receiving element 21. The light receiving circuit 22 includes a plurality of switch elements 25. The output terminals of the light receiving elements 21 are connected to one lead portion of the switch elements 25, and the other lead portion is connected to the input terminal of the light receiving side CPU 24. Are connected in common.
[0033]
Further, the control terminal 25 A provided in each switch element 25 is connected to the output terminal of the light receiving side CPU 24 through the shift register 23. Each switch element 25 is always in an off state, and a drive signal is sequentially given from the light receiving side CPU 24 to each switch element 25 via the shift register 23, and thus, the switch elements 25 are turned on. Only the light reception signal of the light receiving element 21 is taken into the light receiving side CPU 24.
[0034]
Further, the light receiving side CPU 24 takes in the clock pulse signal from the light projecting circuit 14 via a line L1 connecting the light projecting and receiving devices 10 and 20, and this clock pulse signal (that is, the light projecting of each light projecting element 11). The predetermined switch element 25 is turned on in synchronization with the timing. Specifically, among the light projecting elements 11 arranged in the upper and lower rows, the light receiving elements 21 arranged in the same order as the light projecting elements 11 at the moment when the light projecting elements 11 of a predetermined order project an optical signal. Only the continuous switch element 25 is turned on. Thereby, only when each light receiving element 21 receives light from the normal counterpart light projecting element 11, the light receiving signal output by the light receiving element 21 is taken into the light receiving side CPU 24.
[0035]
The light reception signals sequentially enabled from the respective light receiving elements 21 are also given to the inputs of the first comparator 28 and the second comparator 29, respectively, and the outputs of the first comparator 28 and the second comparator 29 are given to the light receiving side CPU 24. It is supposed to be. Among these, the first comparator 28 corresponds to the “determination unit” of the present invention, and here, a detection threshold value V1 for determining whether each optical axis is in a light incident state or a light shielding state is set. The detection threshold value V1 is set to a level between the light receiving signal level from the light receiving element 21 when there is an object between the light projecting element 11 and the light receiving element 21 which are regular counterparts, for example. . On the other hand, the second comparator 29 corresponds to the “comparison means” of the present invention, and is output from the light receiving element 21 of the optical axis that is lower than the detection threshold V1 and that has the work table W1 interposed therebetween. An optical axis designating threshold value V2 that is higher than the received light signal level is set.
[0036]
2. Control operation of the light receiving side CPU
(1) When adjusting the optical axis
For example, when a mode change switch (not shown) provided in the projector 10 or the light receiver 20 is set to “optical axis adjustment mode” and activated, the projector 10 sequentially projects the light projecting elements 11 in synchronization with the clock pulse signal. And the clock pulse signal is given to the photoreceiver 20 side. Upon receiving this clock pulse signal, the light receiving side CPU 24 executes the flowchart shown in the display control routine of FIG.
[0037]
First, in step S1, the optical axis number K is initialized to 1, and when a high level signal of the clock pulse signal is detected (“Y” in step S2), the first optical axis (eg, in FIGS. 1 and 2 in FIG. 1 and FIG. 2). The light receiving signal from the light receiving element 21 on the uppermost optical axis) is validated and the received light amount level is read. At the same time, the output signal from the second comparator 29 is read. Here, the light receiving side CPU 24 can recognize based on the output signal from the second comparator 29 whether or not the light receiving level at the light receiving element 21 of the first optical axis is equal to or greater than the optical axis designating threshold V2.
[0038]
Then, the processes in steps S2 and S3 are sequentially executed up to the 24th optical axis (for example, the lowermost optical axis in FIGS. 1 and 2) (steps S4 and 5). When the process is executed up to the 24th optical axis (“Y” in step S4), in step S6, the minimum received light quantity level is extracted from the received light quantity levels equal to or higher than the optical axis designating threshold value V2. Note that the optical axis of the light receiving element 21 showing the received light amount level equal to or higher than the optical axis designating threshold V2 corresponds to the “effective optical axis” of the present invention.
[0039]
Subsequently, in step S7, the display of the optical axis adjustment display unit 30 is controlled with a display pattern corresponding to the minimum received light amount level. Specifically, the light receiving side CPU 24 calculates a relative value of the minimum received light amount level with respect to the detection threshold value V1, and controls the display of the optical axis adjustment display unit 30 with a display pattern corresponding to the relative value. As shown in FIG. 4, the optical axis adjustment display unit 30 is configured by a bar graph display composed of four indicator lamps arranged in the vertical direction. For example, the first indicator lamp 31 has a relative value of 120% or more. When the second indicator lamp 32 has a relative value of 110 to 120%, the third indicator lamp 33 has a relative value of 100 to 110%, and the fourth indicator lamp 34 has a relative value of 100% or less. Each is controlled to light up.
[0040]
(2) Specific operation
For example, as shown in FIG. 5A, when the light receiver 20 is disposed at a slight inclination with respect to the light projector 10, the optical axis on the lower side is substantially coincident and most of the light from the light projecting element 11 is that of the counterpart. Although the light is received by the light receiving element 21, the amount of deviation of the optical axis is increased toward the upper side, and the amount of light received by the light receiving element 21 is gradually reduced (see the solid line A in FIG. 5B). Further, the amount of received light is substantially zero for the optical axis on which the work table W1 is interposed. Then, the light-receiving side CPU 24 executes the display control routine described above, reads the light receiving amount level corresponding to each optical axis, and the output signal from the second comparator 29 by making a light projection / reception operation for all the optical axes. (Steps S1 to S5). As a result, the received light level at the 11th to 14th optical axes with the work table W1 interposed is lower than the optical axis designating threshold value V2, and the received light level at the other optical axes exceeds the optical axis designating threshold value V2. It is recognized that the 1st to 10th and 15th to 24th optical axes are designated as effective optical axes.
[0041]
Then, the received light amount level at the first optical axis having the largest optical axis deviation amount among these effective optical axes is extracted as the minimum received light amount (step S6). The relative value of the minimum received light amount with respect to the detection threshold value V1 is, for example, 90%, and only the fourth indicator lamp 34 of the optical axis adjustment display unit 30 is turned on (step S7). Therefore, if the operator looks at the display pattern of the optical axis adjustment display unit 30, the received light level at the optical axis with the largest optical axis deviation among the effective optical axes is 100% or less with respect to the detection threshold value V1. I can know that. Then, the light receiver 20 is rotated so that the third indicator lamp 33 of the optical axis adjustment display unit 30 is also turned on (in the arrow direction in FIG. 5A). Then, the light reception level at the upper optical axis gradually increases (see the two-dot broken line B in FIG. 2B), and by moving further, all the effective optical axes coincide, and the light reception level is for detection. The stability level is 120% or more with respect to the threshold value V1, and the optical axis can be adjusted to a stable state in which light incident and light shielding by the detected object can be reliably detected.
[0042]
(3) During detection operation
When the mode selector switch is switched to the “detection mode” after the optical axis adjustment is completed, the light projecting / receiving operation is sequentially executed for all the optical axes in synchronization with the clock pulse signal. Here, since the light receiving side CPU 24 recognizes that the effective optical axis is the 1st to 10th and 15th to 24th optical axes by executing the display control routine, it synchronizes with each light projecting / receiving operation of the effective optical axis. When the output signal of the first comparator 28 is read and an output signal indicating light shielding (an output signal when the light receiving signal level falls below the detection threshold V1 by the first comparator 28) is received, the operation display unit 26 is displayed. While lighting up, a detection signal is output to an external device via the output line 27. For example, in FIG. 1, when an operator's hand (corresponding to a detected object) or the like enters between the projector 10 and the light receiver 20, the operation display unit 26 performs a lighting operation assuming that the detected object is detected. . That is, the multi-optical axis photoelectric sensor of this embodiment has a so-called fixed blanking function.
[0043]
3. Effects of this embodiment
As described above, according to the present embodiment, the optical axis adjustment display unit 30 corresponds to the minimum light reception level among the light reception levels on the effective optical axis excluding the optical axis on which the work table W1 is interposed. Display pattern is displayed. Therefore, even when an object other than the object to be detected such as the work table W1 is present on a part of the optical axis, a display pattern that eliminates the influence of this object can be displayed on the optical axis adjustment display unit 30, and the light The axis can be adjusted accurately.
[0044]
Further, it is possible to automatically designate the effective optical axis without the work table W1 based on the output signal from the second comparator 29 in which the optical axis designation threshold value V2 is set. An accurate display pattern can be displayed on the optical axis adjustment display unit 30 (configuration of claim 2).
[0045]
Further, the display pattern according to the relative value which is the ratio between the minimum received light amount level and the detection threshold value in the effective optical axis is displayed on the optical axis adjustment display unit 30, and the optical axis adjustment display unit 30 is configured. Since each display pattern is configured to be displayed as a bar graph using the first to fourth indicator lamps, the optical axis adjustment can be easily performed with easy visual recognition of the degree of optical axis adjustment (claims 6, 8, and 10). Equivalent to configuration).
[0046]
Second Embodiment
The second embodiment corresponds to the configuration of claim 4. The difference from the embodiment is in the detection operation, and the other points are the same as those in the first embodiment. Therefore, the same reference numerals as those in the first embodiment are attached and the redundant description is omitted, and only different points will be described next.
[0047]
For example, instead of the fixed work table W1, there may be a moving object (an object other than the detected object) that blocks, for example, the 11th to 14th optical axes at predetermined intervals. Therefore, in the present embodiment, the optical axis adjustment mode is executed in advance with the moving object interposed therebetween to specify the effective optical axis, and all the optical axes (1st to 24th) are always detected during the detection operation. While performing a detection operation (all optical axis detection operation) based on the output signal from the corresponding first comparator 28, when receiving a control signal output in synchronization with the intrusion timing of the moving object, for a predetermined time, A detection operation (effective optical axis detection operation) is performed based on an output signal from the first comparator 28 corresponding to the effective optical axis (1-10, 15-24th). That is, the entire optical axis detection operation is performed when the moving object has not entered, and the effective optical axis detection operation is performed when the moving object has entered. That is, the multi-optical axis photoelectric sensor of this embodiment has a so-called muting function.
[0048]
<Third Embodiment>
FIG. 6 shows a third embodiment (corresponding to the invention of claim 5). The difference from the above embodiment lies in the detection operation, and the other points are the same as in the first embodiment. Therefore, the same reference numerals as those in the first embodiment are attached and the redundant description is omitted, and only different points will be described next.
As shown in FIG. 6, the operator may cause the square member W 2 (an object other than the detected object) to enter between the projector 10 and the light receiver 20. In this case, the intrusion position of the square bar is unspecified, but the number of optical axes blocked by the square bar W2 is constant.
[0049]
Therefore, in this embodiment, there is provided an optical axis number setting means (for example, a console) (not shown) for setting the optical axis number blocked by the square member W2. For example, the light receiving side CPU 24 performs the light projecting / receiving operation for all the optical axes in a state where the square member W2 is inserted between the light projecting device 10 and the light receiving device 20, so that the light receiving side CPU 24 has the light receiving amount level for the detection threshold V1 or the optical axis designation It is set by recognizing the number of optical axes (for example, three optical axes) below the threshold value V2. Then, if the number of optical axes whose received light amount level is lower than the detection threshold value V1 or the optical axis designation threshold value V2 is 3 or less, the light receiving side CPU 24 determines whether the first comparator 28 corresponding to all the optical axes. Is ignored, and the detection operation is performed based on the output signal from the first comparator 28 corresponding to the other optical axis. That is, the detection operation with the detected object is not performed only by entering the square member W2.
On the other hand, when the number of optical axes whose received light amount level is lower than the detection threshold value V1 or the optical axis designation threshold value V2 exceeds three optical axes, only the output signal from the first comparator 28 corresponding to the three optical axes is included. Is ignored, and the output signal from the first comparator 28 corresponding to the other optical axis is used as a valid signal for the detection operation. That is, the detection operation with the detected object is executed only when, for example, the operator's hand enters in addition to the square member W2. That is, the multi-optical axis photoelectric sensor of this embodiment has a so-called floating blanking function.
[0050]
<Other embodiments>
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.
(1) The structure provided in the projector 10 side may be sufficient as the optical axis adjustment display part 30 of said each embodiment. Moreover, the structure provided in the exclusive device connected with the light projector 10 or the light receiver 20 may be sufficient.
[0051]
(2) In each of the above embodiments, a configuration may be provided in which notification means for notifying an optical axis (for example, an optical axis number or position) indicating the minimum light reception amount is further provided.
[0052]
(3) In each of the above embodiments, instead of or in addition to the second comparator 29, for example, an input means (for example, a console) for providing an optical axis designation command signal from the outside to the light receiving side CPU is provided. The light receiving side CPU may perform the display control and the detection operation based on the light receiving signals from these effective optical axes, with the optical axis designated by the above or other optical axes as effective optical axes. Corresponding to the configuration of item 3). Specifically, when it is known that the work table W1 is always present on the 11th to 14th optical axes, if the 11th to 14th optical axes are designated by the input means, the other 1 to 10 are designated. The display control and the detection operation are performed using the 15th to 24th optical axes as effective optical axes.
[0053]
(4) In each of the above embodiments, the determination unit and the comparison unit are configured by hardware such as the first comparator 28 and the second comparator 29. However, the present invention is not limited to this, and is configured by software by processing of the light receiving side CPU 24. Also good.
[0054]
(5) The detection threshold value V1 and the optical axis designation threshold value V2 may be at the same level. In this case, the second comparator 29 can be removed and the effective optical axis can be determined based on the output signal from the first comparator 28.
[0055]
(6) In each of the embodiments described above, the display display control and the detection operation are performed based on the received light amount level in each optical axis when the light projecting and receiving operations are completed for all the optical axes. A configuration in which the display display control and the detection operation are performed based on the light reception signal obtained during the light projection / reception operation for all the optical axes is repeated a plurality of times.
[0056]
(7) The object other than the object to be detected may be not only a completely light-shielded object like the work table W1, but also a translucent object or a transparent object that transmits a part of the received light. In this case, if the threshold value V2 for specifying the optical axis is set higher than the light reception signal level from the light receiving element 21 that receives the light from the light projecting element 11 with the object (translucent object or transparent object) interposed therebetween. Good.
[0057]
(8) In each of the above embodiments, the bar graph display is performed according to the relative value that is the ratio between the minimum light reception amount and the detection threshold value V1, but the ratio between the minimum light reception amount and the optical axis designation threshold value is used. It may be a bar graph display corresponding to a certain relative value. Moreover, the structure which displays the relative value itself numerically, for example with a digital display etc. may be sufficient. Moreover, not only a bar graph display but a pie chart display may be used. Furthermore, instead of a relative value that is a ratio between the minimum amount of received light and each threshold value, a display pattern corresponding to the level difference between the two may be used. Moreover, the display pattern which changes the lighting timing, color, etc. of an indicator lamp may be sufficient.
[0058]
(9) Also, not the relative value that is the ratio between the minimum received light amount and each threshold value, but the number of effective optical axes and the light axis level that is equal to or greater than the detection threshold value V1 or the optical axis designation threshold value V2. It may be a display pattern according to a relative amount with a number (including a relative value that is a ratio between the two and a level difference between the two) (corresponding to the configuration of claim 7). For example, in the case of the solid line A in FIG. 5B, a display pattern corresponding to a relative value that is a ratio between the number of effective optical axes 20 and about 9 optical axes equal to or greater than the detection threshold V1 is displayed on the display means (the above bar). Graph display, pie chart display, numerical display, display by changing lighting timing and color, etc.).
[Brief description of the drawings]
FIG. 1 is a perspective view of a multi-optical axis photoelectric sensor according to a first embodiment of the present invention.
FIG. 2 is an electrical configuration diagram.
FIG. 3 is a flowchart showing a display control routine.
FIG. 4 is a simplified diagram of an optical axis adjustment display unit.
FIG. 5 is an explanatory diagram showing the relationship between the shift amount of each optical axis and the received light amount level.
FIG. 6 is a perspective view of a multi-optical axis photoelectric sensor according to a third embodiment.
[Explanation of symbols]
11 ... Projection element
21. Light receiving element
22. Light receiving circuit
23: Shift register
24 ... Reception side CPU
25 ... Switch element
26 ... operation display section
28. First comparator (determination means)
29. Second comparator (comparison means)
30 ... Optical axis adjustment display section (display means)
V1 ... threshold for detection
V2: Optical axis designation threshold
W1 ... Workbench
W2 ... Square

Claims

A plurality of light projecting elements, and a plurality of light receiving elements forming an optical axis in pairs with the plurality of light projecting elements,
A light projecting control means for causing the plurality of light projecting elements to sequentially perform a light projecting operation;
A light receiving control means for performing a light receiving operation for validating a light receiving signal in accordance with a light receiving amount output from a light receiving element corresponding to the light projecting operation of each of the light projecting elements;
A receiving unit that receives the received light signal enabled by the light receiving control unit, compares the received light amount level with a detection threshold value, and determines whether each of the optical axes is incident or blocked based on the comparison result; ,
An optical axis designating unit for designating an optical axis for invalidating the judgment operation by the judgment unit;
Invalidating means for invalidating the determination operation by the determining means of the optical axis specified by the optical axis specifying means;
A multi-optical axis photoelectric sensor comprising detection means for detecting an object to be detected based on a determination result in the determination means of an effective optical axis that is not invalidated by the invalidation means,
Display means;
A multi-optical axis photoelectric sensor comprising: display control means for causing the display means to display a display pattern based on a light reception signal from a light receiving element forming the effective optical axis.

Upon receiving a light reception signal validated by the light reception control means, the light reception level is lower than the detection threshold and is higher than the light reception level when an object is interposed on the optical axis. Comprising a first comparing means for comparing with a threshold;
2. The optical axis designating unit designates an optical axis determined by the first comparison unit as a received light amount level equal to or less than the optical axis designating threshold value as an optical axis to be invalidated. Multi-optical axis photoelectric sensor.

Provide input means to specify the optical axis from the outside,
2. The multi-optical axis photoelectric sensor according to claim 1, wherein the optical axis designating unit designates an optical axis to be invalidated based on the optical axis input to the input unit.

Provided with a control signal input means for inputting a control signal from the outside,
The optical axis designating unit designates an optical axis to be invalidated for a predetermined period based on the input of the control signal to the control signal input unit. The multi-optical axis photoelectric sensor described.

An optical axis number setting means for setting the number of optical axes is provided, and the optical axis designating means designates an optical axis corresponding to the optical axis number set by the optical axis number setting means as an optical axis to be invalidated. The multi-optical axis photoelectric sensor according to claim 1 or claim 2, wherein

Extraction means for extracting the minimum amount of received light based on the light reception signal from the light receiving element forming the effective optical axis is provided,
6. The multi-light according to claim 1, wherein the display control means causes the display means to display a display pattern corresponding to the minimum received light amount level extracted by the extraction means. Axis photoelectric sensor.

Second comparison means is provided for comparing the received light amount level of the received light signal validated by the received light control means with a display threshold value higher than the received light amount level in a state where an object is interposed on the optical axis;
The display control means displays a display pattern corresponding to a relative amount between the number of effective optical axes and the number of optical axes determined to be a received light amount level equal to or higher than the display threshold by the second comparison means. The multi-optical axis photoelectric sensor according to claim 1, wherein the multi-optical axis photoelectric sensor is displayed on a means.

The display control unit causes the display unit to display a display pattern corresponding to a relative amount between the minimum received light amount level and a display threshold value higher than the received light amount level when an object is interposed on the optical axis. The multi-optical axis photoelectric sensor according to claim 6.

The multi-optical axis photoelectric sensor according to claim 7 or 8, wherein the display threshold is at the same level as the detection threshold.

The multi-optical axis photoelectric sensor according to claim 1, wherein the display unit includes a bar graph display unit and displays the display pattern in a bar graph.