JP3809735B2

JP3809735B2 - Trinocular rangefinder

Info

Publication number: JP3809735B2
Application number: JP35330298A
Authority: JP
Inventors: 充小林; 豊阿部
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 1998-12-11
Filing date: 1998-12-11
Publication date: 2006-08-16
Anticipated expiration: 2018-12-11
Also published as: JP2000180158A

Description

【０００１】
【発明の属する技術分野】
本発明は、監視空間にスポット光を投光するとともにスポット光により検知対象物の表面に形成される投光スポットまでの距離が規定範囲内か否かに応じた出力を発生する３眼式測距装置に関するものである。
【０００２】
【従来の技術】
一般に、三角測量法の原理を用いて検知対象物までの距離を測定する光電式の測距装置は、図１１に示すように、検知対象物３が存在する可能性のある監視空間にスポット光を投光する投光手段１０と、投光手段１０により検知対象物３の表面に形成される投光スポットの位置を検出する受光手段２０とを備えている。
【０００３】
投光手段１０は、レーザダイオードや発光ダイオードを用いた投光素子１１と、投光素子１１から放射された光を平行光線束であるスポット光として監視空間に投光させる投光光学系１２とを備え、投光素子１１は適宜の駆動信号により駆動される。
【０００４】
また、受光手段２０は、収束光学系（つまり、屈折力が正の光学系）である受光光学系２２を通して監視空間からの光を受光素子２１の受光面に収束ないし結像させて投光スポットに対応した受光スポットを受光素子２１の受光面に形成する。受光素子２１の出力は信号処理回路２３に入力され、受光光学系２２の中心と受光素子２１の受光面における基準点（通常は受光面の有効長の中心点）との距離、投光光学系１２と受光光学系２２との光軸間の距離、受光素子２１の受光面における基準点に受光スポットが形成されるときの投光光学系２２の中心から検知対象物３までの距離、受光素子２１の受光面内での受光スポットの位置などを用い、基線長三角測量法を適用して検知対象物３までの距離が求められる。信号処理回路２３では、求めた距離が規定範囲内か否かを判断し、規定範囲内の距離であるときに出力をアクティブにする。なお、図１１における一点鎖線で囲んだ部位はセンサを構成し、このセンサに対して投光素子１１の駆動信号は外部から与えられる。
【０００５】
いま説明を簡単にするために、図１２に示すように、投光素子１１から検知対象物３までの距離が基準距離Ｌであるときに、受光素子２１の受光面の中心位置に受光スポットが形成されるものとし、受光素子２１の受光面を、図１３に示すように受光素子２１の受光面のうち検知対象物３が基準距離Ｌよりも近距離Ｌ１（＜Ｌ）に位置するときに受光スポットが形成される近距離受光部５Ｂと、図１４に示すように受光素子２１の受光面のうち検知対象物３が基準距離Ｌよりも遠距離Ｌ２（＞Ｌ）に位置するときに受光スポットが形成される遠距離受光部５Ａとに分けるものとする。信号処理回路２３は、たとえば、近距離受光部５Ｂに受光スポットが形成されるときにのみ出力をアクティブにするのである。受光素子２１としては受光スポットの位置に対応する信号値の出力が得られるＰＳＤやリニアＣＣＤのような位置検出素子を用いてもよいが、遠距離受光部５Ａと近距離受光部５Ｂとのどちらに受光スポットが形成されているかを検出するだけで目的を達成することができるから、たとえば受光スポットの移動方向（図の上下方向）に２個のフォトダイオードを配列した形の位置検出素子を用いると信号処理回路２３の構成が簡単になる。
【０００６】
この動作を簡単にまとめると、図１５のようになる。つまり、検知動作を開始すると、投光素子１１に駆動信号が供給されて（Ｓ１）投光素子１１から光が放射され（Ｓ２）、検知対象物３にスポット光が照射される。スポット光により検知対象物３の表面に投光スポットが形成されると、受光素子２１の受光面に受光スポットが形成される（Ｓ３）。ここで、受光素子２１において受光スポットが近距離受光部５Ｂに形成されているときには（Ｓ４）、信号処理回路２３は出力をオン（つまり、アクティブ）にする（Ｓ５）。また、受光素子２１において近距離受光部５Ｂに受光スポットが形成されていないときには（Ｓ４）、信号処理回路２３は出力をオフ（つまり、非アクティブ）にする（Ｓ６）。
【０００７】
このような測距装置は、製造ラインなどにおいて検知対象物３が所定の距離範囲内に存在するか否か、あるいは検知対象物３の寸法が所定範囲内か否かなどを検出するために広く用いられている。
【０００８】
【発明が解決しようとする課題】
ところで、上述のように投光手段１０と受光手段２０とを１個ずつ備える従来の測距装置では、検知対象物３が基準距離Ｌに存在するときの投光スポットの中心と受光光学系２２の中心とを通る直線が受光素子２１の受光面の中心を通るように配置される。一方、距離の検知精度を高めるために投光スポットはできるだけ直径を小さくしてあるが、実際には完全な点ではなく有限の直径を有している。したがって、図１６に示すように、投光光学系１２と受光光学系２２との光軸を含む平面に直交しかつ検知対象物３が基準距離Ｌに存在するときの投光スポットの中心と受光光学系２２の中心とを通る直線を含む平面、および基準距離Ｌに位置する平面によってスポット光を切り取った領域（つまり、図１６の斜線領域Ｍ）に検知対象物３が存在する場合にも、受光素子２１の近距離受光部５Ｂに受光スポットが形成されることになる。つまり、検知対象物３が基準距離Ｌよりも近距離に存在することを検知しようとしているにもかかわらず、基準距離Ｌよりも遠距離Ｌ３に検知対象物３が存在する場合でも誤検知する場合がある。
【０００９】
本発明は上記事由に鑑みて為されたものであり、その目的は、投光手段から投光するスポット光が有限の直径を有していることに起因する距離の誤検知を防止した３眼式測距装置を提供することにある。
【００１０】
【課題を解決するための手段】
請求項１の発明は、監視空間にスポット光を投光する投光手段と、スポット光とは異なる光軸を有しかつ互いに光軸が異なる収束光学系である２個の受光光学系と、各受光光学系を通して監視空間からの光をそれぞれ受光しスポット光により検知対象物の表面に形成される投光スポットに対応して受光面に形成される受光スポットの位置に応じて三角測量法により求めた検知対象物までの距離が基準距離より近距離であるときに出力をアクティブにする２個の受光手段と、両受光手段の出力がともにアクティブであるときに出力をアクティブにする論理積手段とを備え、スポット光と受光光学系の光軸とが一つの平面に含まれ、かつ両受光光学系がスポット光を対称軸として互いに対称の関係になるように配置され、両受光手段は検知対象物までの距離が基準距離より遠距離であるときに受光スポットが形成される領域を近距離であるときに受光スポットが形成される領域よりも投光手段に近くなるように配置しているものである。この構成によれば、各受光手段では距離が基準距離より遠距離の検知対象物を誤検知する可能性があるとしても、各受光手段に対応する受光光学系の光軸が異なることによって両受光手段では誤検知が生じる可能性のある範囲が異なっており、論理積手段は両受光手段の出力がともにアクティブであるときに出力をアクティブにするから、論理積手段の出力を用いることによって誤検知の可能性を大幅に低減させることができる。とくに、誤検知の可能性がある領域が互いに重複しないように受光光学系を配置しておけば、誤検知を確実に防止することが可能になる。
【００１１】
請求項２の発明は、請求項１の発明において、前記投光手段が規定されたタイミングで間欠的に発光する投光素子を備えるものである。この構成によれば、投光素子に連続的に通電されることがないから、通電に伴う投光素子の経時的な出力の低下を抑制して長寿命の測距装置を提供することが可能になる。
【００１２】
請求項３の発明は、請求項２の発明において、前記各受光手段がそれぞれ発振回路を備えるとともに、各発振回路の出力により規定されたタイミングで間欠的に動作し、前記投光手段が前記両発振回路の出力の一方がアクティブであると出力をアクティブにする論理和回路を備え、前記投光素子が論理和回路の出力がアクティブであるときにスポット光を投光するものである。この構成によれば、各受光手段が間欠的に動作するから消費電力が低減され、また各受光手段が各別の発振回路によって個別に動作しながらも、各受光手段の動作時には投光素子を点灯させるから、投光手段と受光手段とを同期させて動作させることになり検知対象物までの距離を確実に検出することができる。しかも、両受光手段が異なるタイミングで動作するから両受光手段が外来ノイズの影響を同時に受ける可能性が低くなり、耐ノイズ性も高くなる。
【００１３】
請求項４の発明は、請求項２の発明において、前記各受光手段が共通の発振回路を備えるとともに、前記発振回路の出力により規定されたタイミングで間欠的に動作し、前記投光手段が前記発振回路の出力がアクティブであるときに発光するものである。この構成によれば、１つの発振回路で２つの受光手段と投光手段とのタイミングを制御するから回路構成が簡単になり、しかも各受光手段の動作周期を請求項３の発明と等しく設定しているとすれば、投光素子の発光周期は請求項３の発明よりも短くなる可能性があり、結果的に投光素子の長寿命化につながる。
【００１４】
【発明の実施の形態】
（第１の実施の形態）
本実施形態の基本構成は、図１に示すように、２組の受光手段２０ａ，２０ｂを備え、かつ両受光素子２０ａ，２０ｂの出力を論理積手段としてのアンド回路２４に入力し、アンド回路２４の出力を受光手段２０ａ，２０ｂの出力として用いる点が図１１に示した従来構成との主な相違点である。他の構成は基本的には図１１に示した従来構成と同様である。
【００１５】
さらに具体的に説明する。投光手段１０は、投光素子１１および投光光学系１２を備え、投光素子１１を適宜の駆動信号で制御することにより投光素子１１から光を放射させ、投光素子１１から放射された光を投光光学系１２に通すことによって監視空間にスポット光を投光させる。スポット光はほぼ平行な光線束になっている。
【００１６】
一方、受光手段２０ａ，２０ｂは、それぞれ位置検出素子である受光素子２１ａ，２１ｂを備え、各受光素子２１ａ，２１ｂの前方にはそれぞれ受光光学系２２ａ，２２ｂが配置される。受光光学系２２ａ，２２ｂは収束光学系であって、検知対象物３にスポット光が照射されることによって検知対象物３の表面に形成される投光スポットを受光素子２１ａ，２１ｂの受光面に収束ないし結像させて受光スポットを形成する。あるいは投光スポットを光源とみなせば、受光光学系２２ａ，２２ｂは投光スポットからの光を受光素子２１ａ，２１ｂの受光面に集光して受光スポットを形成する機能を有する。受光光学系２２ａ，２２ｂを通して受光素子２１ａ，２１ｂの受光面に形成される受光スポットは、スポット光の投光方向において検知対象物３の位置が変化すれば、図１の上下方向に移動することになる。したがって、受光素子２１ａ，２１ｂには図１の上下方向における受光スポットの位置を検出することができるものを用いる。
【００１７】
本実施形態においては、投光素子１１から検知対象物３までの距離が基準距離Ｌであるときに各受光素子２１ａ，２１ｂの受光面の中心に受光スポットの中心が位置するように設計されているものとして説明する。ただし、この配置は説明を簡単にするための便宜的なものであって、本発明の技術的範囲を制限する趣旨ではない。しかして、以下では、各受光素子２１ａ，１２ｂにおいて検知対象物３が基準距離Ｌよりも近距離に位置するときに受光スポットが形成される領域を近距離受光部５Ｂａ，５Ｂｂとし、検知対象物３が基準距離Ｌよりも遠距離に位置するときに受光スポットが形成される領域を遠距離受光部５Ａａ，５Ａｂとして説明する。また、本発明では検知対象物３までの距離が規定範囲内か否かに応じた出力を発生させるから、受光素子２１ａ，２１ｂとしては、２個のフォトダイオードを受光スポットの移動方向に配列した形の位置検出素子を用いることが可能である。この場合、各フォトダイオードをそれぞれ遠距離受光部５Ａａ，５Ａｂと近距離受光部５Ｂａ，５Ｂｂとして用いるようにすれば、両フォトダイオードの出力の大小関係によって検知対象物３が基準距離Ｌよりも遠距離側に存在するか近距離側に存在するかを判断することができる。もちろん、受光素子２１ａ，２１ｂとしてはフォトダイオードを用いるもののほかＰＳＤやリニアＣＣＤのような位置検出素子を用いてもよい。
【００１８】
各受光素子２１ａ，２１ｂの出力はそれぞれ信号処理回路２３ａ，２３ｂに入力され、各受光素子２１ａ，２１ｂの近距離受光部５Ｂａ，５Ｂｂに受光スポットが形成されているか否かが判断される。上述のような２個のフォトダイオードを配列した形の位置検出素子であれば、両フォトダイオードの出力値の大小を比較するだけで受光スポットが近距離受光部５Ｂａ，５Ｂｂに形成されているか否かを知ることができ、信号処理回路２３ａ，２３ｂの回路構成が簡単になる。また、ＰＳＤやリニアＣＣＤを用いる場合には、基線長三角測量法の原理を用いた演算を施すことにより検知対象物３までの距離を求めることができる。また、ＰＳＤやリニアＣＣＤを採用する場合には、演算結果を閾値と比較することによって検知対象物３が基準距離Ｌより近距離側か否かを判断するから、閾値を適宜に設定すれば基準距離Ｌを電気的に調節することが可能になる。なお、本実施形態においては受光光学系２２の位置を調節するなどして基準距離Ｌを光学的に調節する。
【００１９】
各信号処理回路２３ａ，２３ｂは、各受光素子２１ａ，２１ｂの近距離受光部５Ｂａ，５Ｂｂに受光スポットが形成されているときに出力をアクティブ（ここでは、Ｈレベル）にする。両信号処理回路２３ａ，２３ｂの出力はアンド回路２４に入力され、両信号処理回路２３ａ，２３ｂの出力の論理積が出力される。つまり、アンド回路２４の出力は両信号処理回路２３ａ，２３ｂの出力がともにアクティブであるときに出力をアクティブ（ここでは、Ｈレベル）にする。逆に言えば、両信号処理回路２３ａ，２３ｂの出力のうち一方でも非アクティブ（Ｌレベル）であれば、アンド回路２４の出力は非アクティブであって検知対象物３は基準距離Ｌよりも近距離には存在しないと判断される。
【００２０】
ここで、受光光学系２２ａ，２２ｂの光軸は投光光学系１２の光軸と異なりかつ互いに異なっていれば、本発明の目的をある程度達成することができるが、本実施形態では、投光光学系１２の光軸と受光光学系２２ａ，２２ｂの光軸とが一つの平面に含まれるようにし、かつ両受光光学系２２ａ，２２ｂが投光光学系２１の光軸を対称軸として互いに対称の関係になるように配置してある。また、両受光素子２１ａ，２１ｂは遠距離受光部５Ａａ，５Ａｂが近距離受光部５Ｂａ，５ｂｂよりも投光手段１０に近くなるように配置してある。このような配置を採用すれば、両受光手段２０ａ，２０ｂについて誤検知の可能性がある領域が互いに重複することがなく、アンド回路２４によって誤検知の可能性を確実に防止することが可能になる。
【００２１】
すなわち、各受光手段２０ａ，２０ｂについて誤検知が生じる可能性のある領域は、上述したように、投光光学系１２と受光光学系２２ａ，２２ｂとの光軸を含む平面に直交しかつ検知対象物３が基準距離Ｌに存在するときの投光スポットの中心と受光光学系２２ａ，２２ｂの中心とを通る直線を含む平面、および基準距離Ｌに位置する平面によってスポット光を切り取った領域（つまり、図１の斜線領域Ｍ１，Ｍ２）である。したがって、本実施形態のような位置関係に配置するとすれば、図１の斜線領域Ｍ１，Ｍ２は互いに重複することがない。その結果、図１に示すように、受光手段２０ａにおいて検知対象物３が斜線領域Ｍ１に存在して出力がアクティブになる場合でも、受光手段２０ｂについては検知対象物３が斜線領域Ｍ２に存在せずに出力が非アクティブに保たれ、このようなときにはアンド回路２４の出力は非アクティブであるから、誤検知が防止されることになる。
【００２２】
同様に、図２に示すように、受光手段２０ｂにおいて検知対象物３が斜線領域Ｍ２に存在して出力がアクティブになる場合でも、受光手段２０ａについては検知対象物３が斜線領域Ｍ１に存在せずに出力が非アクティブに保たれるから、アンド回路２４の出力は非アクティブになり、誤検知が防止される。
【００２３】
ところで、図３に示すように、両受光手段２０ａ，２０ｂに対応する斜線領域Ｍ１，Ｍ２に検知対象物３ａ，３ｂが存在する場合には、両受光素子２１ａ，２１ｂの近距離受光部５Ａａ，５Ａｂに受光スポットが形成されるが、受光スポットは両受光素子２１ａ，２１ｂの遠距離受光部５Ｂａ，５Ｂｂにも跨る形で形成されることになる。ここで、近距離受光部５Ａａ，５Ａｂと遠距離受光部５Ｂａ，５Ｂｂとでの受光光量の比率を考慮すると、遠距離受光部５Ｂａ，５Ｂｂのほうが検知対象物３ａ，３ｂに近いことによって受光光量が相対的に大きくなる。つまり、受光素子２１ａ，２１ｂの受光面に形成される受光スポットの重心位置は、遠距離受光部５Ｂａ，５Ｂｂ側に偏っているから、信号処理部２３ａ，２３ｂでは検知対象物３ａ，３ｂが基準距離Ｌよりも遠距離に位置すると判断することになり、誤検知は生じないのである。
【００２４】
結局、本実施形態の構成を採用すれば、基準距離Ｌよりも遠距離に存在する検知対象物３に対して誤検知が生じることはなく、検知対象物３が基準距離Ｌよりも近距離に存在するときにのみアンド回路２４の出力がアクティブになる。
【００２５】
本実施形態の動作を簡単にまとめると、図４のようになる。つまり、検知動作を開始すると、投光素子１１に駆動信号が供給されて（Ｓ１）投光素子１１から光が放射され（Ｓ２）、検知対象物３にスポット光が照射される。検知対象物３に投光スポットが形成されると、受光素子２１ａ，２１ｂの受光面に受光スポットが形成される（Ｓ３）。ここで、両受光素子２１ａ，２１ｂにおいて受光スポットがともに近距離受光部５Ｂａ，５Ｂｂに形成されているときには（Ｓ４，Ｓ５）、アンド回路２４の出力をオン（つまり、アクティブ）にする（Ｓ６）。また、少なくとも一方の受光素子２１ａ，２１ｂにおいて近距離受光部５Ｂａ，５Ｂｂに受光スポットが形成されていないときには（Ｓ４，Ｓ５）、アンド回路２４の出力をオフ（つまり、非アクティブ）にする（Ｓ７）。
【００２６】
ところで、投光素子１１は連続的に点灯させると投光素子１１の通電時間が長くなり、投光素子１１の劣化を早めることになる。そこで、図５に示すように、発振回路３１の出力によって信号処理回路２３（一方の信号処理回路のみを記載している）を間欠的に動作させ、さらにこの発振回路３１の出力を駆動回路１３を通して投光素子１１に与えることにより、投光素子１１を間欠的に発光させる構成を採用するのが望ましい。つまり、投光素子１１の発光のタイミングは発振回路３１の出力の周期およびデューティによって決定され、投光素子１１の発光期間に同期して信号処理回路２３が動作するのである。ここで、発振回路３１の出力の周期は検知対象物３の移動速度に応じて決定されるので、デューティは信号処理回路２３が正常動作可能な最短時間に設定され、電力消費が抑制される。上述のように投光手段１０と受光手段２０とが同期して間欠的に動作するから、外乱光による誤検出も抑制されることになる。なお、受光素子２１と信号処理回路２３と発振回路３１とは本実施形態では集積化されている（図５に一点鎖線で囲んだ部分が集積化された部分である）。
【００２７】
図５の回路構成では、図６（ａ）のように発振回路３１から間欠的にパルス信号が出力され、投光素子１１は図６（ｂ）のように間欠的に発光する。また、受光素子２１の遠距離受光部５Ａと近距離受光部５Ｂとの出力はそれぞれ図６（ｃ）（ｄ）のようになる。信号処理回路２３は、図６（ｅ）のように近距離受光部５Ｂの出力値が遠距離受光部５Ａの出力値よりも大きくなる期間を抽出し、図６（ｆ）のように出力をアクティブにする。なお、信号処理回路２３は、投光素子１１の発光間隔の一周期分だけ出力状態（アクティブ、非アクティブの別）を保持する。したがって、投光素子１１の発光間隔の１周期の経過までに出力状態が変化しない場合は同じ出力状態が継続され、１周期の経過までに出力状態が変化していれば出力状態を変化させる。
【００２８】
本実施形態は、２つの受光手段２０ａ，２０ｂを備えるから、図５の回路は具体的には図７に示す形で適用される。つまり、各受光手段２０ａ，２０ｂに設けた各信号処理回路２３ａ，２３ｂにおいて発振回路３１を共用し、発振回路３１の出力に同期させて両信号処理回路２３ａ，２３ｂを動作させる。また、発振回路３１の出力は駆動回路１３を通して投光素子１１に駆動信号として与えられ、投光素子１１を間欠的に発光させる。図７の回路構成においても一点鎖線で囲んだ部分は集積化される。
【００２９】
したがって、図８（ａ）（ｂ）のように各信号処理回路２３ａ，２３ｂには発振回路３１から間欠的にパルス信号が入力され、信号処理回路２３ａ，２３ｂが間欠的に動作することになる。また、投光素子１１には駆動回路１３から図８（ｃ）のようにパルス信号が間欠的に供給され、投光素子１１が間欠的に発光する。ここで、両信号処理回路２３ａ，２３ｂと投光素子１１とは一つの発振回路３１の出力を受けて動作するから、動作タイミングは一致している。
【００３０】
一方の受光手段２０ａにおける受光素子２１ａの遠距離受光部５Ａａと近距離受光部５Ｂａとの出力はそれぞれ図８（ｄ）（ｅ）のようになり、信号処理回路２３ａでは、図８（ｆ）のように近距離受光部５Ｂａの出力値が遠距離受光部５Ａａの出力値よりも大きくなる期間を抽出し、図８（ｇ）のように出力をアクティブにする。また、他方の受光手段２０ｂにおける受光素子２１ｂの遠距離受光部５Ａｂと近距離受光部５Ｂｂとの出力はそれぞれ図８（ｈ）（ｉ）のようになり、信号処理回路２３ｂでは、図８（ｊ）のように近距離受光部５Ｂｂの出力値が遠距離受光部５Ａｂの出力値よりも大きくなる期間を抽出し、図８（ｋ）のように出力をアクティブにする。このような動作によって、両受光手段２０ａ，２０ｂの出力がともにアクティブになると、図８（ｌ）のようにアンド回路２４の出力がアクティブになる。
【００３１】
要するに、両信号処理回路２３ａ，２３ｂと投光素子１１との動作タイミングを１つの発振回路３１で制御するから、回路構成が簡単であり、また、単位時間当たりの各信号処理回路２３ａ，２３ｂの動作時間と投光素子１１の発光時間とが一致するから、２個の信号処理回路２３ａ，２３ｂを設けているにもかかわらず、投光素子１１の通電時間を比較的少なくすることができる。
【００３２】
以上説明したように、投光素子１１を間欠的に発光させることによって、投光素子１１の劣化が抑制され、長寿命化が可能になるのである。
【００３３】
（第２の実施の形態）
本実施形態は、図９に示すように、各信号処理回路２３ａ，２３ｂごとに発振回路３１ａ，３１ｂを設けているものである。また、両発振回路３１ａ，３１ｂの出力の一方がアクティブであるときに出力をアクティブにする論理和回路３２を設け、論理和回路３２の出力を駆動回路１３に入力している。他の構成は第１の実施の形態と同様である。
【００３４】
このような構成を採用すると、各発振回路３１ａ，３１ｂから図１０（ａ）（ｂ）のように異なるタイミングでパルスが発生しているとすると、図１０（ｃ）のように論理和回路３２からは両発振回路３１ａ，３１ｂの出力の論理和が出力される。図９において一点鎖線で囲んだ部分は集積化される部分であって、第１の実施の形態では両受光手段２０ａ，２０ｂが異なる構成であったのに対して、本実施形態では同構成の集積回路を用いることが可能になる。
【００３５】
一方の受光手段２０ａにおける受光素子２１ａの遠距離受光部５Ａａと近距離受光部５Ｂａとの出力はそれぞれ図１０（ｄ）（ｅ）のように発振回路３１ａの出力に同期し、信号処理回路２３ａでは、図１０（ｆ）のように近距離受光部５Ｂａの出力値が遠距離受光部５Ａａの出力値よりも大きくなる期間を抽出し、図１０（ｇ）のように出力をアクティブにする。また、他方の受光手段２０ｂにおける受光素子２１ｂの遠距離受光部５Ａｂと近距離受光部５Ｂｂとの出力はそれぞれ図１０（ｈ）（ｉ）のように発振回路３１ｂの出力に同期し、信号処理回路２３ｂでは、図１０（ｊ）のように近距離受光部５Ｂｂの出力値が遠距離受光部５Ａｂの出力値よりも大きくなる期間を抽出し、図１０（ｋ）のように出力をアクティブにする。このような動作によって、両受光手段２０ａ，２０ｂの出力がともにアクティブになると、図１０（ｌ）のようにアンド回路２４の出力がアクティブになる。
【００３６】
以上説明したように、本実施形態の動作は基本的には第１の実施の形態と同様である。ただし、各受信手段２０ａ，２０ｂの動作タイミングを異ならせることができるから、瞬時的な電力消費は本実施形態のほうが少なくなる。一方、各受光手段２０ａ，２０ｂの動作タイミングを第１の実施の形態と等しく設定した場合には投光素子１１の発光回数がほぼ２倍になるから、投光素子１１の寿命の点では第１の実施の形態のほうが望ましい。両構成のどちらを採用するかは、目的に応じて適宜に選択される。
【００３７】
なお、本発明は２個の受光素子を備えた３眼式の測距装置ではあるが、本発明の動作原理から明らかなように、３個以上の受光素子を配置して検出値の論理積を用いる場合も、当然ながら２個の受光素子の検出値の論理積も用いることになるから、本発明の技術的範囲に属するものである。
【００３８】
【発明の効果】
請求項１の発明の構成によれば、各受光手段では距離が基準距離より遠距離の検知対象物を誤検知する可能性があるとしても、各受光手段に対応する受光光学系の光軸が異なることによって両受光手段では誤検知の可能性が生じる範囲が異なっており、論理積手段は両受光手段の出力がともにアクティブであるときに出力をアクティブにするから、論理積手段の出力を用いることによって誤検知の可能性を大幅に低減させることができる。とくに、誤検知の可能性がある領域が互いに重複しないように受光光学系を配置しておけば、誤検知を確実に防止することが可能になるという利点を有する。
【００３９】
請求項２の発明は、請求項１の発明において、投光手段が規定されたタイミングで間欠的に発光する投光素子を備えるものであり、投光素子に連続的に通電されることがないから、通電に伴う投光素子の経時的な出力の低下を抑制して長寿命の測距装置を提供することが可能になるという利点がある。
【００４０】
請求項３の発明は、請求項２の発明において、各受光手段がそれぞれ発振回路を備えるとともに、各発振回路の出力により規定されたタイミングで間欠的に動作し、投光手段が両発振回路の出力の一方がアクティブであると出力をアクティブにする論理和回路を備え、投光素子が論理和回路の出力がアクティブであるときにスポット光を投光するものであり、各受光手段が間欠的に動作するから消費電力が低減され、また各受光手段が各別の発振回路によって個別に動作しながらも、各受光手段の動作時には投光素子を点灯させるから、投光手段と受光手段とを同期させて動作させることになり検知対象物までの距離を確実に検出することができるという利点がある。しかも、両受光手段が異なるタイミングで動作するから両受光手段が外来ノイズの影響を同時に受ける可能性が低くなり、耐ノイズ性も高くなる。
【００４１】
請求項４の発明は、請求項２の発明において、各受光手段が共通の発振回路を備えるとともに、発振回路の出力により規定されたタイミングで間欠的に動作し、投光手段が発振回路の出力がアクティブであるときに発光するものであり、１つの発振回路で２つの受光手段と投光手段とのタイミングを制御するから回路構成が簡単になり、しかも各受光手段の動作周期を請求項３の発明と等しく設定しているとすれば、投光素子の発光周期は請求項３の発明よりも短くなる可能性があり、結果的に投光素子の長寿命化につながるという利点がある。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態を示す要部構成図である。
【図２】同上の動作説明図である。
【図３】同上の動作説明図である。
【図４】同上の動作説明図である。
【図５】同上の要部ブロック図である。
【図６】図５に示した構成の動作説明図である。
【図７】同上の要部ブロック図である。
【図８】図７に示した構成の動作説明図である。
【図９】本発明の第２の実施の形態を示す要部ブロック図である。
【図１０】同上の動作説明図である。
【図１１】従来例を示す要部構成図である。
【図１２】同上の動作説明図である。
【図１３】同上の動作説明図である。
【図１４】同上の動作説明図である。
【図１５】同上の動作説明図である。
【図１６】同上の動作説明図である。
【符号の説明】
３検知対象物
１０投光手段
１１投光素子
２０ａ，２０ｂ受光手段
２１ａ，２１ｂ受光素子
２２ａ，２２ｂ受光光学系
２３ａ，２３ｂ信号処理回路
２４アンド回路
３１発振回路
３１ａ，３１ｂ発振回路
３２論理和回路[0001]
BACKGROUND OF THE INVENTION
The present invention is a trinocular measurement system that projects a spot light into a monitoring space and generates an output according to whether or not the distance to the projection spot formed on the surface of the object to be detected by the spot light is within a specified range. The present invention relates to a distance device.
[0002]
[Prior art]
In general, a photoelectric distance measuring device that measures the distance to a detection object using the principle of triangulation method, as shown in FIG. 11, spot light in a monitoring space where the detection object 3 may exist. Projecting means 10 for projecting light, and light receiving means 20 for detecting the position of a projecting spot formed on the surface of the detection object 3 by the projecting means 10.
[0003]
The light projecting means 10 includes a light projecting element 11 that uses a laser diode or a light emitting diode, and a light projecting optical system 12 that projects light emitted from the light projecting element 11 into a monitoring space as spot light that is a parallel light bundle. The light projecting element 11 is driven by an appropriate drive signal.
[0004]
The light receiving means 20 converges or forms an image of the light from the monitoring space on the light receiving surface of the light receiving element 21 through the light receiving optical system 22 which is a converging optical system (that is, an optical system having a positive refractive power). A light receiving spot corresponding to the above is formed on the light receiving surface of the light receiving element 21. The output of the light receiving element 21 is input to the signal processing circuit 23, and the distance between the center of the light receiving optical system 22 and the reference point on the light receiving surface of the light receiving element 21 (usually the center point of the effective length of the light receiving surface), the light projecting optical system 12, the distance between the optical axes of the light receiving optical system 22, the distance from the center of the light projecting optical system 22 when the light receiving spot is formed at the reference point on the light receiving surface of the light receiving element 21, the light receiving element The distance to the detection object 3 is obtained by applying the baseline length triangulation method using the position of the light receiving spot in the light receiving surface 21. The signal processing circuit 23 determines whether or not the obtained distance is within the specified range, and activates the output when the distance is within the specified range. In addition, the site | part enclosed with the dashed-dotted line in FIG. 11 comprises a sensor, and the drive signal of the light projection element 11 is given to the sensor from the outside.
[0005]
For simplification of explanation, as shown in FIG. 12, when the distance from the light projecting element 11 to the detection target 3 is the reference distance L, a light receiving spot is formed at the center position of the light receiving surface of the light receiving element 21. As shown in FIG. 13, the light receiving surface of the light receiving element 21 is formed when the detection target 3 is located at a short distance L1 (<L) from the reference distance L. The short distance light receiving portion 5B where the light receiving spot is formed and the light receiving surface of the light receiving element 21 as shown in FIG. 14 receive light when the detection object 3 is located at a distance L2 (> L) farther than the reference distance L. It is assumed that it is divided into a long distance light receiving unit 5A where a spot is formed. For example, the signal processing circuit 23 activates the output only when a light receiving spot is formed in the short distance light receiving unit 5B. As the light receiving element 21, a position detecting element such as a PSD or a linear CCD that can output a signal value corresponding to the position of the light receiving spot may be used. Either the long distance light receiving part 5A or the short distance light receiving part 5B may be used. The purpose can be achieved simply by detecting whether or not a light receiving spot is formed on the surface. For example, a position detecting element in which two photodiodes are arranged in the moving direction of the light receiving spot (vertical direction in the figure) is used. The configuration of the signal processing circuit 23 is simplified.
[0006]
This operation is summarized as shown in FIG. That is, when the detection operation is started, a drive signal is supplied to the light projecting element 11 (S1), light is emitted from the light projecting element 11 (S2), and the detection target 3 is irradiated with spot light. When a light projection spot is formed on the surface of the detection target 3 by the spot light, a light receiving spot is formed on the light receiving surface of the light receiving element 21 (S3). Here, when the light receiving spot is formed in the short distance light receiving portion 5B in the light receiving element 21 (S4), the signal processing circuit 23 turns the output on (that is, active) (S5). When the light receiving spot is not formed in the short distance light receiving portion 5B in the light receiving element 21 (S4), the signal processing circuit 23 turns off the output (that is, inactive) (S6).
[0007]
Such a distance measuring device is widely used for detecting whether or not the detection target 3 is within a predetermined distance range in a production line or the like, or whether or not the size of the detection target 3 is within a predetermined range. It is used.
[0008]
[Problems to be solved by the invention]
By the way, in the conventional distance measuring device having one light projecting means 10 and one light receiving means 20 as described above, the center of the light projecting spot and the light receiving optical system 22 when the detection target 3 exists at the reference distance L. The straight line passing through the center of the light receiving element 21 is arranged so as to pass through the center of the light receiving surface of the light receiving element 21. On the other hand, although the diameter of the light projection spot is made as small as possible in order to improve the distance detection accuracy, it is actually not a perfect point but a finite diameter. Therefore, as shown in FIG. 16, the center of the light projecting spot and the light reception when the detection target 3 exists at the reference distance L that is orthogonal to the plane including the optical axes of the light projecting optical system 12 and the light receiving optical system 22. Even when the detection target 3 is present in a region including a straight line passing through the center of the optical system 22 and a region where the spot light is cut out by a plane located at the reference distance L (that is, the hatched region M in FIG. 16), A light receiving spot is formed in the short distance light receiving portion 5B of the light receiving element 21. That is, even if the detection target 3 is detected at a shorter distance than the reference distance L, the detection target 3 is erroneously detected even when the detection target 3 exists at a distance L3 longer than the reference distance L. There is.
[0009]
The present invention has been made in view of the above-described reasons, and its object is to prevent the erroneous detection of the distance caused by the spot light projected from the light projecting means having a finite diameter. It is to provide a type distance measuring device.
[0010]
[Means for Solving the Problems]
The invention of claim 1 includes a light projecting means for projecting spot light to the monitoring space, two light receiving optical systems which are optical systems different from the spot light and have different optical axes, The light from the monitoring space is received through each light receiving optical system, and by the triangulation method according to the position of the light receiving spot formed on the light receiving surface corresponding to the projection spot formed on the surface of the detection object by the spot light The distance to the detected object Shorter than the reference distance And two light receiving means for activating the output when the output is, and a logical product means for activating the output when the outputs of both light receiving means are both active. The spot light and the optical axis of the light receiving optical system are included in one plane, and the both light receiving optical systems are arranged so as to be symmetrical with respect to the spot light as the symmetry axis. The region where the light receiving spot is formed when the distance is longer than the reference distance is arranged closer to the light projecting means than the region where the light receiving spot is formed when the distance is short. Is. According to this configuration, the distance between the light receiving means is Far from the reference distance Even if there is a possibility that the detection object may be erroneously detected, the range in which erroneous detection may occur is different between the two light receiving means due to the difference in the optical axis of the light receiving optical system corresponding to each light receiving means. Since the means activates the output when the outputs of both the light receiving means are active, the possibility of erroneous detection can be greatly reduced by using the output of the AND means. In particular, if the light receiving optical system is arranged so that areas that may be erroneously detected do not overlap each other, erroneous detection can be reliably prevented.
[0011]
According to a second aspect of the present invention, in the first aspect of the invention, the light projecting means includes a light projecting element that emits light intermittently at a prescribed timing. According to this configuration, since the light projecting element is not continuously energized, it is possible to provide a long-life distance measuring device by suppressing a decrease in output of the light projecting element over time due to energization. become.
[0012]
According to a third aspect of the present invention, in the second aspect of the invention, each of the light receiving means includes an oscillation circuit, and operates intermittently at a timing defined by an output of each of the oscillation circuits. An OR circuit that activates the output when one of the outputs of the oscillation circuit is active is provided, and the light projecting element projects spot light when the output of the OR circuit is active. According to this configuration, the power consumption is reduced because each light receiving means operates intermittently, and the light projecting element is operated when each light receiving means is operated while each light receiving means is individually operated by a separate oscillation circuit. Since it is turned on, the light projecting means and the light receiving means are operated in synchronization, and the distance to the detection target can be reliably detected. Moreover, since both light receiving means operate at different timings, the possibility that both light receiving means are simultaneously affected by external noise is reduced, and noise resistance is also improved.
[0013]
According to a fourth aspect of the present invention, in the invention of the second aspect, each of the light receiving means includes a common oscillation circuit, and operates intermittently at a timing defined by an output of the oscillation circuit. Light is emitted when the output of the oscillation circuit is active. According to this configuration, since the timing of the two light receiving means and the light projecting means is controlled by one oscillation circuit, the circuit configuration is simplified, and the operation cycle of each light receiving means is set equal to that of the invention of claim 3. If so, there is a possibility that the light emission period of the light projecting element is shorter than that of the invention of claim 3, and as a result, the life of the light projecting element is extended.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
As shown in FIG. 1, the basic configuration of the present embodiment includes two sets of light receiving means 20a and 20b, and outputs the outputs of both light receiving elements 20a and 20b to an AND circuit 24 as a logical product means. The point of using 24 outputs as the outputs of the light receiving means 20a and 20b is the main difference from the conventional configuration shown in FIG. Other configurations are basically the same as the conventional configuration shown in FIG.
[0015]
This will be described more specifically. The light projecting means 10 includes a light projecting element 11 and a light projecting optical system 12, and emits light from the light projecting element 11 by controlling the light projecting element 11 with an appropriate drive signal, and is emitted from the light projecting element 11. The spot light is projected into the monitoring space by passing the light through the projection optical system 12. The spot light has a substantially parallel light bundle.
[0016]
On the other hand, the light receiving means 20a and 20b include light receiving elements 21a and 21b, which are position detection elements, respectively, and light receiving optical systems 22a and 22b are arranged in front of the light receiving elements 21a and 21b, respectively. The light receiving optical systems 22a and 22b are converging optical systems, and project light spots formed on the surface of the detection target 3 when the detection target 3 is irradiated with spot light on the light receiving surfaces of the light receiving elements 21a and 21b. A light receiving spot is formed by focusing or imaging. Alternatively, if the light projecting spot is regarded as a light source, the light receiving optical systems 22a and 22b have a function of condensing light from the light projecting spot on the light receiving surfaces of the light receiving elements 21a and 21b to form a light receiving spot. The light receiving spots formed on the light receiving surfaces of the light receiving elements 21a and 21b through the light receiving optical systems 22a and 22b move in the vertical direction in FIG. 1 if the position of the detection target 3 changes in the light projecting direction of the spot light. become. Accordingly, light receiving elements 21a and 21b that can detect the position of the light receiving spot in the vertical direction in FIG. 1 are used.
[0017]
In the present embodiment, when the distance from the light projecting element 11 to the detection target 3 is the reference distance L, the center of the light receiving spot is designed to be positioned at the center of the light receiving surface of each of the light receiving elements 21a and 21b. Explain that it is. However, this arrangement is for convenience of explanation and is not intended to limit the technical scope of the present invention. Accordingly, in the following description, the regions where the light receiving spots are formed when the detection target 3 is located at a shorter distance than the reference distance L in each of the light receiving elements 21a and 12b are referred to as the short distance light receiving portions 5Ba and 5Bb. An area where a light receiving spot is formed when 3 is located farther than the reference distance L will be described as long distance light receiving portions 5Aa and 5Ab. In the present invention, an output is generated according to whether or not the distance to the detection target 3 is within a specified range. Therefore, as the light receiving elements 21a and 21b, two photodiodes are arranged in the moving direction of the light receiving spot. It is possible to use a position detecting element of the shape. In this case, if each photodiode is used as the long-distance light receiving unit 5Aa, 5Ab and the short-distance light receiving unit 5Ba, 5Bb, the detection target 3 is farther than the reference distance L depending on the magnitude of the output of both photodiodes. It can be determined whether it exists on the distance side or the near side. Of course, as the light receiving elements 21a and 21b, a position detecting element such as a PSD or a linear CCD may be used in addition to a photodiode.
[0018]
The outputs of the light receiving elements 21a and 21b are input to the signal processing circuits 23a and 23b, respectively, and it is determined whether or not light receiving spots are formed in the short distance light receiving portions 5Ba and 5Bb of the light receiving elements 21a and 21b. In the case of the position detecting element in which two photodiodes are arranged as described above, whether or not the light receiving spots are formed in the short distance light receiving portions 5Ba and 5Bb only by comparing the output values of the two photodiodes. Thus, the circuit configuration of the signal processing circuits 23a and 23b is simplified. Further, when a PSD or a linear CCD is used, the distance to the detection object 3 can be obtained by performing a calculation using the principle of the baseline length triangulation method. Further, when PSD or linear CCD is adopted, it is determined whether or not the detection object 3 is closer to the reference distance L by comparing the calculation result with the threshold value. The distance L can be adjusted electrically. In the present embodiment, the reference distance L is optically adjusted by adjusting the position of the light receiving optical system 22 or the like.
[0019]
Each signal processing circuit 23a, 23b makes an output active (here, H level) when a light receiving spot is formed in the short distance light receiving portions 5Ba, 5Bb of the light receiving elements 21a, 21b. The outputs of both signal processing circuits 23a and 23b are input to an AND circuit 24, and the logical product of the outputs of both signal processing circuits 23a and 23b is output. That is, the output of the AND circuit 24 becomes active (here, H level) when the outputs of both signal processing circuits 23a and 23b are both active. In other words, if one of the outputs of the signal processing circuits 23a and 23b is inactive (L level), the output of the AND circuit 24 is inactive and the detection target 3 is closer than the reference distance L. It is judged that there is no distance.
[0020]
Here, if the optical axes of the light receiving optical systems 22a and 22b are different from the optical axis of the light projecting optical system 12 and are different from each other, the object of the present invention can be achieved to some extent. The optical axis of the optical system 12 and the optical axes of the light receiving optical systems 22a and 22b are included in one plane, and both the light receiving optical systems 22a and 22b are symmetrical with respect to the optical axis of the light projecting optical system 21. They are arranged so that The light receiving elements 21a and 21b are arranged so that the long distance light receiving portions 5Aa and 5Ab are closer to the light projecting means 10 than the short distance light receiving portions 5Ba and 5bb. If such an arrangement is adopted, the areas where there is a possibility of erroneous detection of both the light receiving means 20a and 20b do not overlap each other, and the AND circuit 24 can reliably prevent the possibility of erroneous detection. Become.
[0021]
That is, as described above, the region where each of the light receiving units 20a and 20b may be erroneously detected is orthogonal to the plane including the optical axes of the light projecting optical system 12 and the light receiving optical systems 22a and 22b and is a detection target. An area in which spot light is cut out by a plane including a straight line passing through the center of the light projection spot when the object 3 is present at the reference distance L and the center of the light receiving optical systems 22a and 22b, and a plane positioned at the reference distance L (that is, , Are hatched areas M1, M2) of FIG. Therefore, if it arrange | positions in the positional relationship like this embodiment, the hatched area | region M1, M2 of FIG. 1 will not mutually overlap. As a result, as shown in FIG. 1, even if the detection target 3 exists in the hatched area M1 in the light receiving means 20a and the output becomes active, the detection target 3 does not exist in the hatched area M2 for the light receiving means 20b. In such a case, since the output of the AND circuit 24 is inactive, erroneous detection is prevented.
[0022]
Similarly, as shown in FIG. 2, even if the detection target 3 exists in the hatched area M2 in the light receiving means 20b and the output becomes active, the detection target 3 does not exist in the hatched area M1 for the light receiving means 20a. Therefore, the output of the AND circuit 24 becomes inactive, and erroneous detection is prevented.
[0023]
By the way, as shown in FIG. 3, when the detection objects 3a and 3b exist in the hatched areas M1 and M2 corresponding to both the light receiving means 20a and 20b, the short distance light receiving portions 5Aa of the both light receiving elements 21a and 21b, Although a light receiving spot is formed on 5Ab, the light receiving spot is formed so as to straddle the long distance light receiving portions 5Ba and 5Bb of both light receiving elements 21a and 21b. Here, considering the ratio of the amount of light received by the short-distance light receiving units 5Aa and 5Ab and the long-distance light receiving units 5Ba and 5Bb, the long-distance light receiving units 5Ba and 5Bb are closer to the detection objects 3a and 3b. Becomes relatively large. That is, the center of gravity position of the light receiving spot formed on the light receiving surfaces of the light receiving elements 21a and 21b is biased toward the long distance light receiving portions 5Ba and 5Bb, so that the detection target objects 3a and 3b are the reference in the signal processing portions 23a and 23b. It will be determined that it is located farther than the distance L, and no false detection will occur.
[0024]
Eventually, if the configuration of the present embodiment is adopted, no erroneous detection occurs with respect to the detection target 3 that exists farther than the reference distance L, and the detection target 3 is closer to the reference distance L. Only when present is the output of the AND circuit 24 active.
[0025]
The operation of this embodiment can be summarized as shown in FIG. That is, when the detection operation is started, a drive signal is supplied to the light projecting element 11 (S1), light is emitted from the light projecting element 11 (S2), and the detection target 3 is irradiated with spot light. When a light projection spot is formed on the detection target 3, a light reception spot is formed on the light receiving surfaces of the light receiving elements 21a and 21b (S3). Here, when both the light receiving elements 21a and 21b have the light receiving spots formed in the short distance light receiving portions 5Ba and 5Bb (S4 and S5), the output of the AND circuit 24 is turned on (that is, active) (S6). . When no light receiving spot is formed on the short distance light receiving portions 5Ba and 5Bb in at least one of the light receiving elements 21a and 21b (S4 and S5), the output of the AND circuit 24 is turned off (that is, inactive) (S7). ).
[0026]
By the way, if the light projecting element 11 is continuously lit, the energization time of the light projecting element 11 becomes longer, and the light projecting element 11 is accelerated. Therefore, as shown in FIG. 5, the signal processing circuit 23 (only one signal processing circuit is described) is intermittently operated by the output of the oscillation circuit 31, and the output of the oscillation circuit 31 is further connected to the drive circuit 13. It is desirable to adopt a configuration in which the light projecting element 11 emits light intermittently by being given to the light projecting element 11. That is, the light emission timing of the light projecting element 11 is determined by the output period and duty of the oscillation circuit 31, and the signal processing circuit 23 operates in synchronization with the light emission period of the light projecting element 11. Here, since the cycle of the output of the oscillation circuit 31 is determined according to the moving speed of the detection target 3, the duty is set to the shortest time during which the signal processing circuit 23 can normally operate, and the power consumption is suppressed. As described above, since the light projecting means 10 and the light receiving means 20 operate intermittently in synchronization, erroneous detection due to disturbance light is also suppressed. Note that the light receiving element 21, the signal processing circuit 23, and the oscillation circuit 31 are integrated in this embodiment (the portion surrounded by the one-dot chain line in FIG. 5 is the integrated portion).
[0027]
In the circuit configuration of FIG. 5, a pulse signal is intermittently output from the oscillation circuit 31 as shown in FIG. 6A, and the light projecting element 11 emits light intermittently as shown in FIG. 6B. Further, the outputs of the long distance light receiving unit 5A and the short distance light receiving unit 5B of the light receiving element 21 are as shown in FIGS. 6C and 6D, respectively. The signal processing circuit 23 extracts a period in which the output value of the short distance light receiving unit 5B is larger than the output value of the long distance light receiving unit 5A as shown in FIG. 6 (e), and outputs the output as shown in FIG. 6 (f). Activate. The signal processing circuit 23 holds the output state (active or inactive) for one cycle of the light emission interval of the light projecting element 11. Therefore, when the output state does not change by the lapse of one cycle of the light emission interval of the light projecting element 11, the same output state is continued, and when the output state has changed by the lapse of one cycle, the output state is changed.
[0028]
Since this embodiment includes two light receiving means 20a and 20b, the circuit of FIG. 5 is specifically applied in the form shown in FIG. That is, the signal processing circuits 23a and 23b provided in the light receiving means 20a and 20b share the oscillation circuit 31, and operate both signal processing circuits 23a and 23b in synchronization with the output of the oscillation circuit 31. The output of the oscillation circuit 31 is given as a drive signal to the light projecting element 11 through the drive circuit 13 and causes the light projecting element 11 to emit light intermittently. Also in the circuit configuration of FIG. 7, the portions surrounded by the alternate long and short dash line are integrated.
[0029]
Therefore, as shown in FIGS. 8A and 8B, pulse signals are intermittently input from the oscillation circuit 31 to the signal processing circuits 23a and 23b, and the signal processing circuits 23a and 23b operate intermittently. . Further, a pulse signal is intermittently supplied to the light projecting element 11 from the drive circuit 13 as shown in FIG. 8C, and the light projecting element 11 emits light intermittently. Here, since both the signal processing circuits 23a and 23b and the light projecting element 11 operate by receiving the output of one oscillation circuit 31, the operation timings coincide with each other.
[0030]
The outputs of the long-distance light receiving unit 5Aa and the short-distance light receiving unit 5Ba of the light receiving element 21a in one light receiving unit 20a are as shown in FIGS. 8D and 8E, respectively. In the signal processing circuit 23a, FIG. A period in which the output value of the short distance light receiving unit 5Ba is larger than the output value of the long distance light receiving unit 5Aa is extracted, and the output is activated as shown in FIG. Further, the outputs of the long-distance light-receiving unit 5Ab and the short-distance light-receiving unit 5Bb of the light-receiving element 21b in the other light-receiving unit 20b are as shown in FIGS. 8 (h) and (i), respectively. In the signal processing circuit 23b, FIG. A period in which the output value of the short distance light receiving unit 5Bb is larger than the output value of the long distance light receiving unit 5Ab as shown in j) is extracted, and the output is activated as shown in FIG. When the outputs of both the light receiving means 20a and 20b are activated by such an operation, the output of the AND circuit 24 is activated as shown in FIG.
[0031]
In short, since the operation timing of both the signal processing circuits 23a and 23b and the light projecting element 11 is controlled by one oscillation circuit 31, the circuit configuration is simple, and each signal processing circuit 23a and 23b per unit time is simple. Since the operation time and the light emission time of the light projecting element 11 coincide with each other, the energization time of the light projecting element 11 can be relatively reduced despite the provision of the two signal processing circuits 23a and 23b.
[0032]
As described above, by causing the light projecting element 11 to emit light intermittently, deterioration of the light projecting element 11 is suppressed, and a long life can be achieved.
[0033]
(Second Embodiment)
In the present embodiment, as shown in FIG. 9, oscillation circuits 31a and 31b are provided for the respective signal processing circuits 23a and 23b. Further, an OR circuit 32 is provided that activates an output when one of the outputs of both the oscillation circuits 31 a and 31 b is active, and the output of the OR circuit 32 is input to the drive circuit 13. Other configurations are the same as those of the first embodiment.
[0034]
When such a configuration is adopted, assuming that pulses are generated at different timings as shown in FIGS. 10A and 10B from the oscillation circuits 31a and 31b, the OR circuit 32 is used as shown in FIG. Outputs the logical sum of the outputs of both oscillation circuits 31a and 31b. In FIG. 9, the portion surrounded by the alternate long and short dash line is a portion to be integrated. In the first embodiment, the light receiving means 20a and 20b are different from each other. An integrated circuit can be used.
[0035]
The outputs of the long-distance light receiving part 5Aa and the short-distance light receiving part 5Ba of the light receiving element 21a in one light receiving means 20a are respectively synchronized with the output of the oscillation circuit 31a as shown in FIGS. Then, a period in which the output value of the short distance light receiving unit 5Ba is larger than the output value of the long distance light receiving unit 5Aa as shown in FIG. 10 (f) is extracted, and the output is activated as shown in FIG. 10 (g). Further, the outputs of the long-distance light receiving part 5Ab and the short-distance light receiving part 5Bb of the light receiving element 21b in the other light receiving means 20b are synchronized with the output of the oscillation circuit 31b as shown in FIGS. The circuit 23b extracts a period in which the output value of the short distance light receiving unit 5Bb is larger than the output value of the long distance light receiving unit 5Ab as shown in FIG. 10 (j), and activates the output as shown in FIG. 10 (k). To do. When the outputs of both the light receiving means 20a and 20b are activated by such an operation, the output of the AND circuit 24 is activated as shown in FIG.
[0036]
As described above, the operation of this embodiment is basically the same as that of the first embodiment. However, since the operation timings of the receiving units 20a and 20b can be made different, instantaneous power consumption is reduced in the present embodiment. On the other hand, when the operation timing of each of the light receiving means 20a and 20b is set equal to that of the first embodiment, the number of times of light emission of the light projecting element 11 is almost doubled. One embodiment is preferred. Which of the two configurations is adopted is appropriately selected according to the purpose.
[0037]
Although the present invention is a trinocular distance measuring device having two light receiving elements, as is apparent from the operation principle of the present invention, three or more light receiving elements are arranged and the logical product of the detected values is obtained. Of course, the logical product of the detection values of the two light receiving elements is also used, and therefore belongs to the technical scope of the present invention.
[0038]
【The invention's effect】
Invention of Claim 1 According to the configuration of each The distance of the light receiving means Far from the reference distance Even if there is a possibility that the detection object may be erroneously detected, the range in which the possibility of erroneous detection is different between the two light receiving means due to the difference in the optical axis of the light receiving optical system corresponding to each light receiving means. Since the output is activated when the outputs of both light receiving means are active, the possibility of erroneous detection can be greatly reduced by using the output of the AND means. In particular, if the light receiving optical system is arranged so that areas with the possibility of erroneous detection do not overlap each other, there is an advantage that erroneous detection can be surely prevented.
[0039]
According to a second aspect of the present invention, in the first aspect of the invention, the light projecting means includes a light projecting element that emits light intermittently at a prescribed timing, and the light projecting element is not continuously energized. Therefore, there is an advantage that it is possible to provide a long-range distance measuring device by suppressing a decrease in output of the light projecting element over time due to energization.
[0040]
According to a third aspect of the present invention, in the second aspect of the present invention, each light receiving means includes an oscillation circuit and operates intermittently at a timing defined by the output of each oscillation circuit. A logical sum circuit that activates the output when one of the outputs is active is provided, and the light projecting element projects spot light when the output of the logical sum circuit is active, and each light receiving means is intermittent Power consumption is reduced, and each light receiving means is individually operated by a separate oscillation circuit, but the light emitting element is turned on when each light receiving means is operated. There is an advantage that the distance to the detection target can be reliably detected because the operation is performed in synchronization. Moreover, since both light receiving means operate at different timings, the possibility that both light receiving means are simultaneously affected by external noise is reduced, and noise resistance is also improved.
[0041]
According to a fourth aspect of the present invention, in the second aspect of the present invention, each light receiving means includes a common oscillation circuit and operates intermittently at a timing defined by the output of the oscillation circuit. The circuit configuration is simplified because the timing of the two light receiving means and the light projecting means is controlled by a single oscillation circuit, and the operation cycle of each light receiving means is defined in claim 3. If it is set equal to that of the invention, the light emission period of the light projecting element may be shorter than that of the invention of claim 3, and as a result, there is an advantage that the life of the light projecting element is extended.
[Brief description of the drawings]
FIG. 1 is a main part configuration diagram showing a first embodiment of the present invention;
FIG. 2 is an operation explanatory view of the above.
FIG. 3 is an operation explanatory diagram of the above.
FIG. 4 is an operation explanatory view of the above.
FIG. 5 is a main part block diagram of the above.
6 is an operation explanatory diagram of the configuration shown in FIG. 5. FIG.
FIG. 7 is a block diagram of the main part of the above.
8 is an operation explanatory diagram of the configuration shown in FIG. 7;
FIG. 9 is a principal block diagram showing a second embodiment of the present invention.
FIG. 10 is an operation explanatory diagram of the above.
FIG. 11 is a main part configuration diagram showing a conventional example.
FIG. 12 is an operation explanatory diagram of the above.
FIG. 13 is an operation explanatory diagram of the above.
FIG. 14 is a diagram for explaining the operation of the above.
FIG. 15 is an operation explanatory diagram of the above.
FIG. 16 is an operation explanatory diagram of the above.
[Explanation of symbols]
3 objects to be detected
10 Projection means
11 Emitting element
20a, 20b light receiving means
21a, 21b Light receiving element
22a, 22b Light receiving optical system
23a, 23b Signal processing circuit
24 AND circuit
31 Oscillator circuit
31a, 31b Oscillator circuit
32 OR circuit

Claims

Light projecting means for projecting spot light to the monitor space, two light receiving optical systems which are optical systems different from each other and having different optical axes, and the monitor space through each light receiving optical system The distance to the detection object obtained according to the position of the light receiving spot formed on the light receiving surface corresponding to the light projecting spot formed on the surface of the detection object by the spot light respectively received from the reference light is the reference distance Two light receiving means for activating the output when the distance is closer , and a logical product means for activating the output when the outputs of both light receiving means are both active . The optical axis is included in one plane, and both light receiving optical systems are arranged so as to have a symmetric relationship with respect to the spot light as an axis of symmetry, and both light receiving means are located farther from the reference distance than the reference distance. In 3-eye distance measuring apparatus characterized that you have placed as close to the light emitting means from a region where the light receiving spot is formed when the area where the light-receiving spot is formed a short distance when.

The trinocular distance measuring device according to claim 1, wherein the light projecting means includes a light projecting element that emits light intermittently at a prescribed timing.

Each of the light receiving means has an oscillation circuit and operates intermittently at a timing specified by the output of each oscillation circuit. The light projecting means activates an output when one of the outputs of the both oscillation circuits is active. 3. The trinocular distance measuring device according to claim 2, further comprising: a logical sum circuit that emits light when the output of the logical sum circuit is active.

Each of the light receiving means has a common oscillation circuit and operates intermittently at a timing defined by the output of the oscillation circuit, and the light projecting means emits light when the output of the oscillation circuit is active. The trinocular distance measuring device according to claim 2, wherein: