JP3730673B2 - Optical information reader - Google Patents

Description

但し、Ｗは合焦レンズ位置検出用光電変換器３２ＰＳの全受光幅。
この式は、入射光量が変化しても成立する。
【００３０】
式（７）を変形すれば、次式となる。
Δｆ＝〔｛ＷＩ_ｂ／（Ｉ_ａ＋Ｉ_ｂ）｝−ｇ〕／ａ （８）
式（８）によるΔｆは、合焦レンズ位置測定信号である。この場合のΔｆを、以下、Δｆ_ｍと書く。
原理的には、式（４）による合焦レンズ位置指令信号Δｆ_ｃと、式（８）による合焦レンズ位置測定信号Δｆ_ｍとを、図２の合焦レンズ位置サーボ回路３４中の差動増幅器（エラー増幅器）の各入力端子に印加することが可能である。
合焦動作が開始すると、Δｆが増大し、従ってΔｆ_ｍが増大するが、Δｆ_ｍがΔｆ_ｃと一致した所で、合焦レンズ３１が停止する。そして、合焦動作が終了する。
【００３１】
図１５に戻って、電子的分圧器３５及びエラー増幅器Ｅ（即ち合焦レンズ位置サーボ回路３４）について説明する。
Ａ端からの電流信号Ｉ_ａ、及びＢ端からの電流信号Ｉ_ｂは、それぞれ電圧信号に変換され、Ｖ_ａ，Ｖ_ｂとなる。
Ａ端からの電圧信号Ｖ_ａは加算器Ａに印加され、Ｂ端からの電圧信号Ｖ_ｂは加算器Ａ、及びエラー増幅器Ｅの−に印加される。
加算器Ａでは、和信号Ｖ_ａ＋Ｖ_ｂが作られる。
和信号Ｖ_ａ＋Ｖ_ｂは、電子的分圧器ＶＤの第１の入力端子に印加される。
式（７）は、電圧信号Ｖ_ａ、Ｖ_ｂ並びにＶ_ａ＋Ｖ_ｂを用いて、次のように、書き換えられる。
Ｖ_ｂ／（Ｖ_ａ＋Ｖ_ｂ）＝（ａΔｆ_ｃ＋ｇ）／Ｗ （９）
Ｖ_ｂ＝（Ｖ_ａ＋Ｖ_ｂ）（ａΔｆ_ｃ＋ｇ）／Ｗ （１０）
式（１０）は、入射光量が変化しても成立する。
中央制御装置（例えばマイクロプロセッサユニット）９は、分圧制御信号ＤＣＳを、電子的分圧器ＶＤの第２の入力端子に送る。
分圧制御信号ＤＣＳによる分圧比は、（ａΔｆ_ｃ＋ｇ）／Ｗである。
電子的分圧器ＶＤは、和信号Ｖ_ａ＋Ｖ_ｂに、分圧比（ａΔｆ_ｃ＋ｇ）／Ｗを乗じた値を出力する。
【００３２】
電子的分圧器ＶＤの出力と、実際のＶ_ｂとを、エラー増幅器Ｅ（即ち合焦レンズ位置サーボ回路３４に入力し、その出力を可動線輪３３Ｃに印加する。
合焦動作が開始すると、Δｆの増大につれてΔｆ′が増大し、従って、実際のＶ_ｂが増大するが、Ｖ_ｂが（Ｖ_ａ＋Ｖ_ｂ）（ａΔｆ_ｃ＋ｇ）／Ｗと合致した所で、合焦レンズ３１が停止する。そして、合焦動作が終了する。
かくして、合焦レンズ３１を、中央制御装置（例えばマイクロプロセッサユニット）９が指令した位置（ｘ＝Δｆ_ｃ）に、保持する事ができる。
式（４）、（８）に基づく合焦動作（図２参照）と、式（１０）に基づく合焦動作（図１５）は、本質的に等価である。但し、演算回数は後者の方が少なくて済む。
図１５の電子的分圧器ＶＤには、デジタルアナログコンバータＡ／Ｄや、Ｅ^２ＰＯＴ（サイコーネー）等が利用できる。
合焦レンズ位置検出のための専用光源は、必要でない。
【００３３】
（第１の実施例の測距装置）
第１の実施例に使用する第１の測距装置について説明する。
図４は、同実施例に使用する第１の測距装置の原理説明図である。
図４（ａ）において、２は光源、４１は振動ミラー、Ｔは被読取物、６Ｌは測距用受光レンズ、６ｓは小径の測距用光電変換素子、ａ，は振動ミラー４１の走査中心線（即ち読取方向中心線）、ｂ_２は測距用受光レンズ６Ｌの受光中心線である。
測距専用の投光光源は、必要としない。
【００３４】
説明の便のため、
走査中心線ａ_１と受光中心線ｂ_２との間の距離をｅ、
振動ミラー４１と被読取物Ｔとの間の距離（又は測距用受光レンズ６Ｌと被読取物Ｔとの間の距離）をＤ_ｘ、
走査中心線ａ_１と被読取物Ｔとの交点をＡ、
受光中心線ｂ_２と被読取物Ｔとの交点をＢ、
点Ａから測距用受光レンズ６Ｌに向かう反射光線をａ_２、
振動ミラー４１から点Ｂに向かう光線をｂ_１、
振動ミラー４１の中心点から線分ＡＢを見込む角（走査中心線ａ_１と点Ｂに向かう光線ｂ_１とのなす角＝振り角）をθ
とする。
簡単のため、走査中心線ａ_１と被読取物Ｔとは直交している（即ち読取中心線ａ_１と被読取物Ｔとは直交している）ものとする。
ｅの値は所与であるから、振り角θが計測可能ならば、被読取物Ｔまでの距離Ｄ_Ｘは、次式で与えられる。
Ｄ_Ｘ＝ｅ／ｔａｎθ （１１）
【００３５】
さて、測距用光電変換素子６ｓは小径であるから、受光中心線ｂ_２から外れて到来する光線（例えば点Ａから到来する光線ａ_２）は、図示の如く、測距用光電変換素子６ｓから外れることとなり、受光されない。
従って、測距用光電変換素子６ｓで受光される光線は、受光中心線ｂ_２に沿って到来する光線のみである。
走査ビームが点Ａを通過する時点ｔ_Ａは、走査用同期信号に基づいて決定することが出来る。走査ビームが点Ｂを通過する時点ｔ_Ｂは、測距用光電変換素子６ｓの出力が極大になる時点であるから、出力極大時点を検知することによって、検知することが出来る。出力極大時点の検出には、公知の手段が使用される。
【００３６】
時点ｔ_Ａと時点ｔ_Ｂとの時間差をｔ_ｄとすれば、振動ミラー４１の中心点から線分ＡＢを見込む角（振り角）θは、時間差ｔ_ｄに比例する。即ち、
θ＝ｋｔ_ｄ （１２）
但し、ｋは走査速度によって決まる比例定数。
従って、被読取物Ｔまでの距離Ｄ_ｘは、次式によって与えられる。
Ｄ_Ｘ＝ｅ／ｔａｎ（ｋｔ_ｄ）＝ｅ ｃｏｔ（ｋｔ_ｄ） （１３）
図４（ｂ）は、図４（ａ）における被読取物Ｔを、点Ａを中心として、反時計方向に角ψだけ、回転させた場合を示す。破線Ｔ′は、被読取物の回転後の現在位置を示す。
角ψの回転によって誤差Ｄ_Ｘ′が生じる。Ｄ_Ｘ′は次式によって与えられる。
Ｄ_Ｘ′＝ｅ ｔａｎψ （１４）
角ψ（ラディアン）が微小であれば、Ｄ_Ｘ′≒ｅψ≒０であるから、焦点整合に支障を来す虞（おそれ）はない。
【００３７】
（第１の実施例の振動ミラー形走査装置）
第１の実施例に使用する振動ミラー形走査装置４について説明する。
図６（ａ）及び（ｂ）は、同振動ミラー形走査装置の水平断面図及び垂直断面図である。
図６（ａ）及び（ｂ）において、４１_１は第１の反射ミラー（走査用ミラー）、４１_２は第２の反射ミラー（受光用ミラー）、４２は可動部、４６はホルダ、４７は固定継鉄（ヨーク）、４９は駆動巻線である。
可動部４２は、可動部本体と回転軸４２５とを含有し、可動部本体は、板状、棒状又は立体状であって、２個の可動磁石４２１、４２１と、可動継鉄４２２とを含有する。
第１の反射ミラー４１_１と可動部本体と第２の反射ミラー４１_２とは、一体的に構成する。
【００３８】
駆動巻線４９が通電されていない時は、可動体は図示の位置に静止する。
可動体を静止位置から適宜の角度回動させて釈放すると、可動磁石４２１と継鉄４７との間に吸引力（磁気バネ力）が発生するから、可動体４２は、自由往復振動を開始する。
駆動巻線４９が通電された時は、駆動電流が可動磁石４２１の磁界と交差するから、可動磁石４２１に正又は負の偶力が作用する。その結果、可動体４２は強制振動を開始する。
第１の反射ミラー４１_１は、合焦装置２から到来した光ビームを、周期的に反射偏向させる。第２の反射ミラー４１_２は、被読取物Ｔ上の飛点（光の移動点）から集光兼偏向手段５ＣＰを経由して到来する反射光を、周期的に反射偏向させて、光電変換器７に向けて射出する。
集光兼偏向手段５ＣＰは、集光レンズと反射プリズムとを、図示の如く、一体に構成したもので良いし、集光レンズと反射プリズムとを互いに別体として構成したものでも良い。
（尚、上記の振動ミラー形走査装置４については、この発明の出願人の出願に係る特願平６−８７１５７号（特開平７−２６１１０９号公報）の明細書及び図面に詳細に説明されている。）
【００３９】
（第１の実施例の受光光学系）
第１の実施例に使用される受光光学系５について説明する。
図１に戻って、５ＣＰは集光兼偏向手段であって、集光作用と偏向作用とを兼ね備えたものである。
集光兼偏向手段５ＣＰと第２の反射ミラー４２_２（図６（ａ）参照）とは、共同して、受光光学系５を構成する。
集光兼偏向手段５ＣＰは、被読取物Ｔ上の飛点（光の移動点）から到来する反射光を集光すると共に、集光した反射光の進行方向を変換して、第２の反射ミラー４１_２に向けて射出する。第２の反射ミラー４１_２は、到来した反射光を、周期的に反射偏向させて、光電変換器７に入射させる。
この実施例では、集光兼偏向手段５ＣＰの受光口径を拡大することによって、受光光量を増加することが出来る。
【００４０】
（第１の実施例の光源）
図１において、２は光源である。光源２としては、例えば、可視光ビームを発光する可視光半導体レーザ、又は、面発光形構造のＬＥＤに極小径のメサ構造を用いたものを使用する。
光源２には、集光レンズを組み込むことが出来る。但し、該集光レンズは、前記の側部光を保存するものでなければならない。
【００４１】
（第１の実施例の光源駆動回路）
第１の実施例の光源駆動回路について説明する。
光源２からの投光は、ビーム状光束であるので、バーコードと走査装置の距離が変化してもバーコードに入射する光パワーは変化しない。受光レンズに入射するバーコード面上からの反射光は、その距離により変化し、受光口径が一定の場合、受光光量はバーコードからの距離の２乗に反比例する。
測距により得られた距離データをもとに、投光光出力を制御すると、バーコードからの距離が変化しても受光量を一定に保つ事ができる。（但し、最大出射出力は、光放射安全規格等により制限される事がありる。）
【００４２】
図１７は、光源駆動回路２Ｄのブロック図である。この図は、光源にレーザダイオードを用いた場合である。
レーザダイオードＬＤから発光した光の一部は、光出力を観測する為のモニタ用ホトダイオードＭＰＤに入射する。モニタ用ホトダイオードＭＰＤは、レーザダイオードＬＤの発光出力に比例したモニタ電流を発生する。モニタ電流は抵抗Ｒで電圧信号ＥＣに変換され、エラー増幅器Ｅの−端子に入力される。
エラー増幅器Ｅの＋端子には、光出力制御電圧ＬＰＣＳが入力される。
このモニター電圧ＥＣは、エラー増幅器Ｅで光出力制御電圧ＬＰＣＳと比較され、同一電圧となる様、レーザの発光出力が制御される。
上記の光出力制御電圧ＬＰＣＳは、例えば集中制御装置（例えばマイクロプロセッサユニット）９から送出された光出力制御信号（論理値）が、ＤＡコンバータＤ／Ａによってアナログ量に変換されてなるものである。
【００４３】
（第１の実施例の温度補償装置）
図１において、ＴＳは温度センサである。温度センサＴＳの温度測定信号を用いて、合焦装置３及び光源駆動回路２Ｄの温度補償を行うことが出来る。
温度センサＴＳとしては、温度特性が既知な感温素子（例えばサーミスタ、ダイオードなど）が利用できる。
サーミスタは、温度によって抵抗値が変化する素子であるから、その抵抗値を抵抗電圧変換回路により電圧値に変換し、その電圧値をＡ／Ｄコンバータでディジタル信号に変換してから、集中制御装置（例えばマイクロプロセッサユニット）９に入力する。
合焦装置３の合焦レンズ位置サーボ回路３４に対して、例えば温度測定信号に比例する信号を加算（減算）することが出来る。これによって、温度変動に伴う焦点の変動を防止することが出来る。その結果、合焦レンズとして、プラスチック製レンズの使用が可能となる。
又、光源駆動回路２Ｄに対して、例えば温度測定信号に比例する別の信号を加算（減算）することが出来る。これによって、受光光量に対する温度変動の影響が除去される。
【００４４】
（第２の実施例）
この出願の発明による光学的情報読取装置の第２の実施例について説明する。
第２の実施例は、第１の実施例に可変絞り装置を付加したものに相当する。
図７（ａ）は、第２の実施例に使用する第１の可変絞り装置の動作原理図である。
図７（ａ）において、２は光源、３１は合焦レンズ、Ｉ_１は可変円形絞り、ＩＣは絞り制御回路である。
上記の可変円形絞りＩ_１と、絞り制御回路ＩＣと、図示しない円形絞り駆動機構とは、共同して、第１の可変絞り装置１０を構成する。
可変円形絞りＩ_１及び円形絞り駆動機構の構造と機能は、例えばカメラの分野において公知のものと同様である。可変円形絞りＩ_１の開口（アパーチャ）形状は、開口口径が変化しても変化せず、常に円形である。
絞り制御回路ＩＣは、測距装置６からの距離信号を、直接又はマイクロプロセッサ９を介して受けて、絞り制御信号に変換し、円形絞り駆動機構に印加する。
円形絞り駆動機構は、絞り制御信号に基づいて、可変円形絞りＩ_１の開口口径を調節する。
回動調節後の可変円形絞りＩ_１の開口口径は、距離信号の１次関数となる。
【００４５】
図７（ｂ）は、第２の実施例に使用する第２の可変絞り装置の動作原理図である。
図７（ｂ）において、２は光源、３１は合焦レンズ、Ｉ_２は可変平行四辺形絞り、ＩＣは可変平行四辺形絞り制御回路である。
上記の可変平行四辺形絞りＩ_２と、絞り制御回路ＩＣと、図示しない平行四辺形絞り駆動機構とで、第２の可変絞り装置１０を構成する。
可変平行四辺形絞りＩ_２及び平行四辺形絞り駆動機構の構造と機能は、例えばカメラの分野において公知のものと同様である。可変平行四辺形絞りＩ_２の開口は、横幅（短辺長）だけが変化する。
絞り制御回路ＩＣは、測距装置６からの距離信号を、直接又はマイクロプロセッサ９を介して受けて、絞り指令信号に変換し、平行四辺形絞り駆動機構に印加する。平行四辺形絞り駆動機構は、絞り指令信号に基づいて、可変平行四辺形絞りＩ_２の開口の横幅（短辺長）だけを調節する。
回動調節後の可変円形絞りＩ_２の開口口径は、距離信号の１次関数となる。
【００４６】
可変絞り装置の有用性について、更に詳細に説明する。
図９は、合焦レンズ通過後のレーザビームの縦断面図である。但し、レーザ光はガウシアン分布を有するものとする。
図９において、３１は合焦レンズであり、ω_ｄは合焦レンズ３１の出射点におけるレーザビームの半径（＝合焦レンズの半径）、ω_Ｏはビームウエスト半径、Ｚ_Ｏは合焦レンズ３１の出射点からビームウエスト位置までの距離である。
このとき、ビームウエスト半径ω_Ｏ及び直径２ω_Ｏは、次式で表わされる。
ω_Ｏ＝ λＺ_Ｏ／（πω_ｄ） （１５）
２ω_ｏ＝２λＺ_Ｏ／（πω_ｄ） （１５′）
但し、λはレーザ光の波長。
【００４７】
いま、合焦レンズ３１の出射点におけるレーザビームの半径ω_ｄも一定、波長λも一定であるとすると、ビームウエスト半径ω_ｏ（及び直径２ω_ｏ）は、ビームウエスト距離Ｚ_ｏの１次関数となる。
式（１５′）をグラフ化すれば、図１０の直線１の通りとなる。
但し、図１０には、便宜上、三つの座標系を記載してあるから、直線１は、距離Ｚ_ｏを横軸、ビームウエスト直径２ω_ｏを縦軸とする座標系（Ｚ_ｏ−２ω_ｏ座標系）上の直線であることに注意されたい。
図１０の直線１から明らかなように、ビームウエスト位置が遠点Ｚ_ｏＦにあるときは、ビームウエスト径２ω_ｏＦは太く、ビームウエスト位置が近点Ｚ_ｏｃにあるときは、ビーム径２ω_ｏｃは細い。
【００４８】
ビームウエスト半径ω_Ｏは、式（８）から明らかなように、レーザ光源の波長λ、レンズの口径（２ω_ｄ）、及びビームウエスト位置Ｚ_Ｏの選定で決まる。
一般には、所定の遠点Ｚ_ＯＦに自動合焦した時に、ビームウエスト半径ω_Ｏが、所望の値ω_ＯＦとなる様に、ω_ｄを選択する。
そうすると、近点Ｚ_ＯＣに自動合焦した時には、ビームウエスト径２ω_ＯＣは、図１０の直線１から明らかなように、所望のビームウエスト径よりも大分小さく（細く）なって仕舞う。即ち、（Ｚ_ＯＦ／Ｚ_ＯＣ）の１になって仕舞う。その結果、近点Ｚ_ＯＣにおける光学解像度が必要以上に上り過ぎて、読取データ以外のソイズ（紙面よごれ、印刷むら等）までも検出して仕舞い、信号のＳ／Ｎを悪化させて仕舞う虞がある。
【００４９】
しかしながら、第２の実施例では、合焦レンズ３１の前位又は後位に、図７の如く、可変絞りＩを配設したから、合焦レンズ３１を近点Ｚ_ＯＣに合焦するときには、並行して可変絞りＩをも自動的に調節し、ω_ｄを小さくすることによって、ビームウエスト半径ω_ＯＣを大きくし、以って上記のＳ／Ｎ比の悪化を防止することが出来る。
図１１は、可変絞り通過後のレーザビームのウエスト位置及び直径を示すグラフであるが、同図の曲線２の極小値、即ち合焦レンズ３１を近点Ｚ_ＯＣに合焦した時のビームウエスト径２ω_ＯＣは、図１０の曲線２のそれに比べて、遥かに大きく（太く）なっており、所望の値（要求値）２ω_ＯＦに近付いていることが解る。
【００５０】
図９に戻って、ω_Ｚはビームウエスト位置から距離Ｚ離れた点におけるレーザビームの半径である。
上記のレーザビームの半径ω_Ｚ及び直径２ω_Ｚは、次式で与えられる。
ω_Ｚ ^２ ＝ ω_Ｏ ^２｛１＋（λ／（πω_Ｏ ^２））^２Ｚ^２｝ （１６）
（２ω_Ｚ）^２＝４ω_Ｏ ^２｛１＋（λ／（πω_Ｏ ^２））^２Ｚ^２｝ （１６′）
ビームウエストが任意の近点Ｚ_ＯＣにある場合について、式（９′）をグラフ化すれば、図１０の曲線２の通りとなる。図１０には、前述の如く、便宜上三つの座標系を記載してあるのであるが、曲線２は、近点Ｚ_ＯＣを原点とし、近点Ｚ_ＯＣからの距離Ｚを横軸とし、レーザビーム直径２ω_Ｚを縦軸をとする座標系（即ち、Ｚ−２ω_Ｚ座標系）上の曲線である。
【００５１】
又、ビームウエストが任意の遠点Ｚ_ＯＦにある場合について、式（１６′）をグラフ化すれば、図１０の曲線３の通りとなる。曲線３は、遠点Ｚ_ＯＦを原点とし、遠点Ｚ_ＯＦからの距離Ｚを横軸とし、レーザビーム直径２ω_Ｚを縦軸とする座標系（即ちＺ−２ω_Ｚ座標系）上の直線である。
（ついでながら、レーザビームの直径２ω_Ｚを、合焦レンズ３１の出射点を原点とする空間座標ｚの関数として表現したいときは、式（１６′）にに対して、例えば、次式を代入すれば良い。
（ビームウエストが近点Ｚ_ＯＣにあるとき） Ｚ＝ｚ−Ｚ_ＯＣ （１７）
（ビームウエストが遠点Ｚ_ＯＦにあるとき） Ｚ＝ｚ−Ｚ_ＯＦ （１７′）
但し、ｚ＝０（原点）は合焦レンズ３１の出射点、ｚ＝Ｚ_ＯＣは近点、ｚ＝Ｚ_ＯＦは遠点である。）
【００５２】
図１０の曲線２から明らかなように、合焦レンズを近点Ｚ_ＯＣに自動合焦した時は、ビーム径２ω_Ｚが近点Ｚ_ＯＣの前後で急激に増大する（太くなる）ため、自動焦点制御の精度向上が必要となる。しかしながら、合焦レンズ３１から被読取物までの距離ｚ（Ｚ_ＯＣ＋Ｚ）は、走査ビームの偏向につれて速い周期で変化し、又被読取物面が湾曲しているときにも同様に速い周期で変化するから、こうした変化に自動焦点制御動作を追従させることは困難である。そのため光学解像度が変化し易い。
【００５３】
しかしながら、第２の実施例では、前述の如く、合焦レンズ３１の前位又は後位に、図７の如く、可変絞りＩを配設したから、合焦レンズ３１を近点Ｚ_ＯＣに合焦するときは、並行して可変絞りＩをも自動的に調節し、ω_ｄを小さくすることによってビームウエスト半径ω_ＯＣを相対的に大きく（太く）するから、式（９）及び（９′）の各右辺の中括弧｛｝内における変数Ｚ^２の係数
（λ／（πω_ＯＣ ^２））^２
が小さくなり、従って近点Ｚ_ＯＣの前後でのω_Ｚ ^２の変化が緩慢となり、ビーム半径ω_Ｚの変化（立上り）も緩慢になる。
図１１によれば、曲線２の曲率が、図１０の曲線２のそれに比べて、遥かに小さくなっていることが解る。
以上要するに、第２の実施例では、自動合焦装置の使用に伴って近点におけるビームウエスト径が細くなり過ぎる事態を回避すると共に、ビーム走査や被読取物表面の湾曲に起因する光路長の変化に基づく光学解像度の変化を、軽減することが出来る。
第２の実施例のその余の事項は、第１の実施例と同様である。
【００５４】
（第３の実施例）
この出願の発明による光学的情報読取装置の第３の実施例について説明する。
第３の実施例は、第１の実施例における合焦装置を下記のものに置換すると共に下記の可変絞り装置を付加したものに相当する。
図８は，第３の実施例に使用する合焦装置３及び可変絞り装置の動作原理図である。
図８において、２は光源、３Ｈは円筒形合焦レンズホルダ、ＦＳは送りねじ、ｇ_１は第１の歯車、ｇ_２は第２の歯車、Ｍは電動モータ、３３は合焦レンズ位置移動手段、Ｉ_３は可回転長方形絞り、ＭＣは合焦レンズ位置制御回路兼長方形絞り回動角制御回路である。
【００５５】
送りネジＦＳは、円筒形合焦レンズホルダ３Ｈの外周面に雄ネジとして形成され、図示しない鏡筒３Ｂの内周面に形成した雌ネジに螺合される。（或は、この関係を逆にして、合焦レンズホルダ３Ｈ側に雌ネジを、鏡筒３Ｂ側に雄ネジを形成するようにしても良い。）両ネジは、共同して、送り機構ＦＭを構成する。
第１の歯車ｇ_１は、回転軸を介して電動モータＭに速結され、第２の歯車ｇ_２は、円筒形合焦レンズホルダ３Ｈの一端面（又は外周面）に対して同軸的に結合される。第２の歯車ｇ_２には光ビームを通過させるための貫通孔が穿設される。両歯車ｇ_１、ｇ_２は、共同して、歯車機構（ｇ_１，ｇ_２）を構成する。
（第２の歯車ｇ_２と円筒形合焦レンズホルダ３Ｈとは一体又は別体に構成することができる。）
【００５６】
送りねじ機構ＦＭと、歯車機構（ｇ_１，ｇ_２）と、電動モータＭと、合焦レンズ位置制御回路兼長方形絞り回動角制御回路ＭＣとは、共同して、合焦レンズ位置移動手段３３を構成する。
合焦レンズ位置制御回路兼長方形絞り回動角制御回路ＭＣは、測距装置６からの距離信号を、直接又はマイクロプロセッサ９を介して受信し、合焦レンズ位置指令信号兼長方形絞り回動角指令信号に変換して、電動モータＭに印加する。
合焦レンズ位置制御指令信号兼長方形絞り回動角制御信号は、距離信号の１次関数となる。
電動モータＭは合焦レンズ位置制御信号に従って回動する。電動モータＭの回動運動は、歯車機構（ｇ_１，ｇ_２）を介して、円筒形合焦レンズホルダ３Ｈに伝達され、送り機構ＦＭによって、軸方向の直線運動に変換される。
移動調節後の合焦レンズ３１の位置は、距離信号の１次関数となる。
（歯車機構（ｇ_１，ｇ_２）の歯数比と、送りねじＦＳのピッチとは、距離信号の比例係数に反映される。）
【００５７】
可回動長方形絞りＩ_３は、回動可能な板体からなり、中心部に長方形の開口を有する。可回動長方形絞りＩ_３は、第２の歯車ｇ_２又は合焦レンズホルダ３Ｈに対して、同心的に結合される。（三者は、一体又は別体に構成される）。
可回動長方形絞りＩ_３と、歯車機構（ｇ_１，ｇ_２）と、電動モータＭと、合焦レンズ位置制御回路兼長方形絞り回動角制御回路ＭＣとは、共同して、可回動長方形絞り装置１０を構成する。
半導体レーザ光源からの光ビームは断面形状が元もと縦長であるから、可回動長方形絞りＩ_３への入射光ビームの断面形状寸法を、可回動長方形絞りＩ_３の開口形状寸法と同程度にすることができる。
【００５８】
このとき、回動転長方形絞りＩ_３を通過してなる光ビームの断面形状寸法は、可回動長方形絞りＩ_３の回転角度に依存し、長方形の開口が水平の時に最小、垂直の時に最大となる。即ち、可回動長方形絞りＩ_３を通過した光ビームの断面形状は、光ビーム断面と開口断面との共通部分（重なり合った部分）からなる形状と同一である。
可回動長方形絞りＩ_３は、歯車機構（ｇ_１，ｇ_２）に連結されているから、合焦レンズ位置制御回路兼長方形絞り回動角制御回路ＭＣからのレンズ位置制御信号兼長方形絞り回動角制御信号に従って回動する。
回動調節後の長方形開口の位置（角度）は、距離信号の１次関数となる。
（歯車機構（ｇ_１，ｇ_２）の歯数比は、距離信号の比例定数に反映される。）
第３の実施例に使用する可変絞り装置の有用性は、第２の実施例におけるそれと同様である。
第３の実施例のその余の事項は、第１の実施例と同様である。
【００５９】
（第４の実施例）
この出願の発明による光学的情報読取装置の第４の実施例について説明する。
第４の実施例は、第１の実施例における振動ミラー形走査装置と受光光学系とを下記のもので置換してなるものに相当する。
図１２中には、第４の実施例の全体構成を示す図である。
図１２において、４は振動ミラー形走査装置、５は受光光学系である。
その余の要素２〜３、６〜９は、図１の要素と同様である。
【００６０】
（第４の実施例の振動ミラー形走査装置）
図３は、第４の実施例に使用する振動ミラー形走査装置を示す図で、（ａ）は水平断面図、（ｂ）は正面図、（ｃ）は側面図である。
図１３において、４１_１は反射ミラー、４２は可動部、４６はホルダ、４７は固定継鉄、４９は駆動巻線である。
第１の実施例に対する、第４の実施例の、構成の差違について説明する。
固定継鉄４７の形状は、略コの字形である。略コの字形は、略口の字形の一辺を削除してなる形状である。
固定継鉄７の一対の対辺〜４７_１，４７_２は、典型的には直線状であるが、緩やかな曲線状とすることも出来る。
【００６１】
可動部４２は、可動部本体と回動軸４２５とを含有する。
可動部本体は、固定継鉄４７の１対の対辺４７_１，４７_２の間に、且前面寄り（開放端寄り）に配設される。
可動部本体と固定継鉄４７とは、略口の字形の磁気回路を構成する。
回動軸４２５は、固定継鉄４７を含む平面に対して、垂直に配設される。
駆動巻線４９，４９はそれぞれ、固定継鉄４７の１対の対辺４７_１，４７_２の前面寄りに巻回される。
唯一の反射ミラー（走査用ミラー）４１_１は可動部４２の前面に固定される。
第４の実施例のその余の構成は、第１の実施例と同一である。
【００６２】
（第４の実施例の受光光学系）
第４の実施例に使用する受光光学系について、説明する。
図１２に戻って、受光光学系５は、ありきたりの集光レンズからなる。
集光レンズ５を通過した反射光は、直接無媒介的に光電変換器７に入射する。
第４の実施例のその余の事項は、第１の実施例と同様である。
【００６３】
（第５の実施例）
この出願の発明による光学的情報読取装置の第５の実施例について説明する。
第５の実施例は、第４の実施例における受光光学系５を、合焦装置３の近傍に移動させると共に、振動ミラー形走査装置の反射ミラーを、受光用ミラーとしても利用する様にしたものに相当する。
第５の実施例は、第１〜第４の実施例に比べて、受光光量が若干減少する。
第５の実施例のその余の事項は、第４の実施例と同様である。
【００６４】
（第６の実施例）
この出願の発明の第６の実施例について説明する。
この出願の発明の第６の実施例は、第１の実施例における測距装置を下記の測距装置で置換したものに相当する。
図５は、この出願の発明の第６の実施例に使用する測距装置６の原理説明図であって、同図（ａ）はその平面図（装置の上方から見た図）、同図（ｂ）はその側面図（装置の側方から見た図）、同図（Ｃ）は同測距装置６に使用する測距用光電変換器６Ｓとその接続関係を示す図である。
【００６５】
図５（ａ）〜（ｃ）において、２は光学情報読取用光源、４１は振動ミラー、６Ｌは測距用受光レンズ、６Ｓは測距用光電変換器、６Ａは差動増幅器である。
測距用光電変換器６Ｓに付された符号ｕは、測距用光電変換器６Ｓの上方向を示す。
符号１_Ｔ，２_Ｔ，及び３_Ｔは，被読取物Ｔ（図示しない。）の代表的な位置を示し、符号１_Ｓ，２_Ｓ，及び３_Ｓは、これらの位置に対応する、反射光からなる走査線（飛点の軌跡）の位置を示す。
被読取物Ｔが２_Ｔから３_Ｔに移動すると（即ち、近付くと）、反射光からなる走査線の軌跡は、２_Ｓから３_Ｓに移動する（即ち、下方に移動する）。このことは、図５（ｂ）を参照することによって、容易に理解することが出来る。
反対に、被読取物Ｔが２_Ｔから１_Ｔに移動すると（遠ざかると）、走査線の軌跡は、２_Ｓから１_Ｓに移動する（上方に移動する）。このことも、同様にして、理解することが出来る。
【００６６】
測距用光電変換器６Ｓは、二つの受光領域Ａ及びＢからなる。受光領域Ａ及びＢの形状は、図５（Ｃ）の如く、正方形乃至長方形を１本の斜線によって２等分してなる形状である。正方形乃至長方形を対角線に沿って分割した場合は、領域Ａ及びＢの形状は直角３角形、そうでない場合は、台形となる。
二つの領域Ａ及びＢは、電気的に絶縁されている。両領域の光電流出力Ｉ_Ａ、Ｉ_Ｂは、走査線（飛点）が表面を通過する時間（距離）に比例する。
測距用光電変換器６Ｓの上下方向の長さを２ｃ、中心から走査線の軌跡までの距離をｄ（−ｃ≦ｄ≦ｃ）とすると、走査線（飛点）が領域Ａを通過する時間は（ｃ−ｄ）に比例し、領域Ｂを通過する時間は（ｃ＋ｄ）に比例するから、
Ｉ_Ａ＝ｐ（ｃ−ｄ）
Ｉ_Ｂ＝ｐ（ｃ＋ｄ）
となる。但し、ｐは比例定数（光の強度に依存する）である。
【００６７】
一方の領域Ａは、差動増幅器６Ａの＋端子に接続され、他方の領域Ｂは、差動増幅器６Ａの−端子に接続される。出力端子には差電圧信号Ｖ_Ｘが得られる。
Ｖ_Ｘ＝−２Ａｐｄ （１８）
但し、Ａは差動増幅器６Ａの利得。
走査線が図５（ｃ）の線２_Ｓ上を通過するときは、領域Ａの出力Ｖ_Ａと領域Ｂの出力Ｖ_Ｂとが同一となるから、差動増幅器６Ａの出力Ｖ_Ｘは、ゼロとなる。
走査線が線３_Ｓ上を通過するとき（被読取物Ｔが近点寄りにあるとき）は、領域Ａの出力Ｖ_Ａが領域Ｂの出力Ｖ_Ｂよりも小となるから、差動増幅器６Ａの出力Ｖ_Ｘは、負の値となる。
走査線が線１ｓ上を通過するとき（被読取物Ｔが遠点寄りにあるとき）は、領域Ａの出力Ｖ_Ａが領域Ｂの出力Ｖ_Ｂよりも大となるから、差動増幅器６Ａの出力Ｖ_Ｘは、正の値となる。
このとき、ｄの符号が負となって、ｄ＝−｜ｄ｜となる。
上式を書き換えれば、次式が得られる。
ｄ＝−Ｖ_Ｘ／２Ａｐ （１８′）
【００６８】
三角測量の理論を利用するため、測距用受光レンズ６Ｓを横切る基線ＢＬを考える（図５（ｂ）参照）。そして、基線ＢＬ（測距用受光レンズ６Ｌ）から被読取物Ｔまでの距離をＤ_Ｘ、走査中心線から測距用受光レンズ６Ｌまでの基線ＢＬ上の距離をｅ、基線ＢＬ（測距用受光レンズ６Ｌ）から測距用光電変換器６Ｓのまでの距離をｆ、測距用受光レンズ６Ｌの光軸から測距用光電変換器６Ｓの一端（ｕ側端部）までの距離をｂとする。
受光光量が略一定値に制御されているときは、被読取物Ｔまでの距離Ｄ_Ｘは、次式によって与えられる。
Ｄ_Ｘ＝ｅｆ／（ｂ＋ｃ−Ｖ_Ｘ／２Ａｐ） （１９）
【００６９】
上記の式（１９）の導出過程は、下記の通りである。
図５（ｂ）によれば、高さがＤ_Ｘで底辺がｅなる直角三角形と、高さがｆで底辺が（ｂ＋ｃ＋ｄ）なる直角三角形を考えることが出来る。両者は、その斜辺が１個同一の線分３′上にあるから、明らかに相似である。相似の理論によれば、
Ｄ_Ｘ／ｅ＝ｆ／（ｂ＋ｃ＋ｄ）
∴Ｄ_Ｘ＝ｅｆ／（ｂ＋ｃ＋ｄ） （２０）
式（２０）に、式（１８′）を代入すると、前記の式（１９）が得られる。
測距用光電変換器６Ｓから差動増幅器６Ａへの接続極性を逆にしたときは、式（１９）の代りに、次式が使用される。
Ｄ_Ｘ＝ｅｆ／（ｂ＋ｃ＋Ｖ_Ｘ／２Ａｐ） （１９′）
【００７０】
光源の輝度が制御されることなく一定ならば、受光光量は、距離の自乗に反比例する。この場合の光電流Ｉ_Ａ、Ｉ_Ｂは、下記の通りとなる。
Ｉ_Ａ＝ｐ（ｃ−ｄ）（Ｄ_Ｏ／Ｄ_Ｘ）^２
Ｉ_Ｂ＝ｐ（ｃ＋ｄ）（Ｄ_Ｏ／Ｄ_Ｘ）^２
∴ Ｖ_Ａ＝Ａｐ（ｃ−ｄ）（Ｄ_Ｏ／Ｄ_Ｘ）^２
Ｖ_Ｂ＝Ａｐ（ｃ＋ｄ）（Ｄ_Ｏ／Ｄ_Ｘ）^２
但し、Ａは増幅器の利得。
Ｖ_Ａ及びＶ_Ｂの和及び差を計算すると、
Ｖ_Ａ−Ｖ_Ｂ＝−２Ａｐｄ（Ｄ_Ｏ／Ｄ_Ｘ）^２
Ｖ_Ａ＋Ｖ_Ｂ＝ ２Ａｐｃ（Ｄ_Ｏ／Ｄ_Ｘ）^２
辺同士で割り算を行って、Ａｐ及び（Ｄ_Ｏ／Ｄ_Ｘ）を消去すれば、
（Ｖ_Ａ−Ｖ_Ｂ）／（Ｖ_Ａ＋Ｖ_Ｂ）＝Ｖ_Ｘ／（Ｖ_Ａ＋Ｖ_Ｂ）＝−ｄ／ｃ
∴ ｄ＝−ｃＶ_Ｘ／（Ｖ_Ａ＋Ｖ_Ｂ） （２１）
上式を、式（２０）に代入すれば、次式が得られる。
Ｄ_Ｘ＝ｅｆ／｛ｂ＋ｃ−ｃＶ_Ｘ／（Ｖ_Ａ＋Ｖ_Ｂ）｝ （２２）
（因みに、受光光量が略一定値に制御されているときは、
Ｖ_Ａ＋Ｖ_Ｂ＝２Ａｐｃとなり、式（２２）は、式（１９）と一致する。）
【００７１】
（第７の実施例）
この出願の発明の第７の実施例について説明する。
この出願の発明の第７の実施例は、第１の実施例における測距装置を下記の測距装置で置換したものに相当する。
図１６は、第７の実施例に使用する測距装置の入力回路のブロック図である。
図１６において、２はバーコード読取走査用の光源、２Ｄは光源駆動回路、６
Ｓは測距用光電変換器、９は集中制御装置（例えば、マイクロプロセッサユニット）である。
第７の実施例においても、測距用の投光光源は、バーコード読取走査用の光源（例えばレーザ）２が利用される。
【００７２】
第７の実施例に使用される、測距用光電変換器６Ｓは、原理的には、第１の実施例に使用された合焦レンズ位置検出用光電変換器３２ＰＳ（図２、３、１５参照）と同一であって、図示の如く、細長形状の受光面と、第１の光電流出力端子ｔ_１と、第２の光電流出力端子ｔ_２と、共通電極とを具有する。
第１及び第２の光電流出力は、受光面への光点の入射位置によって異なる。
いま、受光面の長さを２ｃ、受光面の中心位置から光点の入射位置までの距離をｄとすると、両電流の比は、次の通りである。
Ｉ_２／Ｉ_１＝（ｃ＋ｄ）／（ｃ−ｄ）
＝（１＋ｄ／ｃ）／（１−ｄ／ｃ） （２３）
式（２３）の導出過程は、次の通りである。
第１の出力端子ｔ_１からの第１の光電流Ｉ_１は、光点の入射位置から第２の出力端子ｔ_２までの距離に比例する。この距離は、（ｃ−ｄ）であるから、
Ｉ_１＝ｐ（ｃ−ｄ） （２４）
但し、ｐは比例定数（但し、受光光量には依存する）。
同様に、第２の光電流Ｉ_２は、光点の入射位置から第１の出力端子ｔ_１までの距離に比例する。この距離は、（ｃ＋ｄ）であるから、
Ｉ_２＝ｐ（ｃ＋ｄ） （２５）
式（２５）を式（２４）で除して比例定数ｐを消去すれば、式（２３）が得られる。
【００７３】
第７の実施例においても、振動ミラー形走査装置４、被読取物Ｔ、及び測距用受光レンズ６Ｌが使用されるが、それらは第１の実施例と同様である。
第７の実施例の測距用光電変換器６Ｓは、前述の如く、第１、第６の実施例のものとは相違するが、その配置関係は、第６の実施例（図５（ｂ）参照）と同様である。即ち、第７の実施例の測距用受光レンズ６Ｌ及び測距用光電変換器６Ｓは、基線Ｄ上に配設される。（図示は省略する。）
第７の実施例による測距時には、振動ミラー４１を停止させ、基線Ｄに直角な方向（走査の中心方向、θ＝０゜の方向）に投光する。
この間、各種の制御装置は、測距装置６の受光感度を上げるために、可能な限り、投光ビームは平行光、絞りは開放、発光出力は最大とするように、動作せしめられる。（但し、発光出力は、光放射の安全規格等で制限された範囲内に止めなければならない。）
被読取物Ｔからの反射光Ｌは、測距用受光レンズ６Ｌによって集光され、測距用光電変換器６Ｓの受光面上に結像せしめられる。そして、第１の出力端子ｔ_１に第１の光電流Ｉ_１を、第２の出力端子ｔ_２に第２の光電流Ｉ_２を発生させる。
【００７４】
第１、第２の光電流Ｉ_１、Ｉ_２はそれぞれ、電流電圧変換器Ｉ−Ｖによって電圧信号Ｖ_１、Ｖ_２に変換される。電圧信号Ｖ_１、Ｖ_２はそれぞれ、可変増幅器ＡＭＰによって増幅され、サンプルホールド回路Ｓ／Ｈに入力される。
投光光源２は、光源駆動回路２Ｄにより駆動される。その光量は集中制御装置（例えばマイクロプロセッサユニット）９からの光出力制御信号ＬＰＣＳによって制御される。投光光源２の点灯（消灯）は、点灯（消灯）指令信号ＬＯＳによって制御される。
測距動作中は、周囲光の影響を排除するために、光源２はパルス駆動される。実際の点灯時間は、測定一回当り１０〜１０００マイクロ秒程度である。この時間は、投光光源２及び受光回路のパルス応答速度特性に依拠して、最適値に決定される。
【００７５】
第１、第２の出力端子には、投光光源２の消灯時でも、周囲光によって、電流Ｉ_１ｏｆ、Ｉ_２ｏｆが発生する。
周囲光に由来する電流成分Ｉ_１ｏｆ、Ｉ_２ｏｆの影響を排除するために、消灯時の電圧Ｖ_１ｏｆ、Ｖ_２ｏｆは、ＡＤ変換器Ａ／ＤによってそれぞれＡＤ変換され、ディジタルデータとして、集中制御装置（例えば、マイクロプロセッサユニット）９に入力される。
その直後に、集中制御装置（例えばマイクロプロセッサユニット）９は、点灯指令信号ＬＯＳを発して、投光光源２を点灯させる。
第１、第２のサンプルホールド回路Ｓ／Ｈ、Ｓ／Ｈはそれぞれ、点灯指令信号ＬＯＳに同期して、点灯時の電圧信号Ｖ_１ＯＮ，Ｖ_２ＯＮをサンプルしホールドする。それらの電圧信号Ｖ_１ＯＮ，Ｖ_２ＯＮは、ＡＤ変換器Ａ／ＤによってそれぞれＡ／Ｄ変換され、ディジタルデータとして、集中制御装置（例えばマイクロプロセッサユニット）９に入力される。
【００７６】
集中制御装置（例えばマイクロプロセッサユニット）９の内部には各電圧データが論理値としてストアされているので、次からの演算が容易に実行できる。
点灯時の電圧データＶ_１ＯＮ、Ｖ_２ＯＮから、消灯時の電圧データＶ_１ｏｆ、Ｖ_２ｏｆを減算して、真の測距データＶ_１ｔ，Ｖ_２ｔを計算する。即ち、
Ｖ_１ｔ＝Ｖ_１ＯＮ−Ｖ_１ｏｆ
Ｖ_２ｔ＝Ｖ_２ＯＮ−Ｖ_２ｏｆ
両式から、Ｖ_２ｔ／Ｖ_１ｔを算出する。即ち、
Ｖ_２ｔ／Ｖ_１ｔ＝（Ｖ_２ＯＮ−Ｖ_２ｏｆ）／（Ｖ_２ＯＮ−Ｖ_２ｏｆ）（２６）
Ｖ_２ｔ／Ｖ_１ｔは、前記の式（２３）中のＩ_２／Ｉ_１に相当する。
そこで、上式（２６）を，前記の式（２３）中のＩ_２／Ｉ_１に代入することによって、測距値Ｄ_Ｘを計算できる。

【００７７】
集中制御装置（マイクロプロセッサユニット）９の内部における上記の計算は通常１００μｓｅｃ以下でできる。
測定精度を向上させる為に、前記の測定シーケンスを繰り返し、平均値を出力する。繰り返し回数は通常１０〜２０回である。したがって、１回当りの測定時間は通常１ｍｓｅｃ以下である。
測定精度を良くする為には、投光光量を上げる必要があるが、そこに制限があるのは、前述の通りである。
【００７８】
また、Ａ／Ｄコンバーターの量子化精度を上げる為、点灯時データＶ_１ＯＮおよびＶ_２ＯＮが共に小さな値であった場合、集中制御装置（マイクロプロセッサユニット）９は増幅率切替信号ＡＣＳにより、増幅率を増加させ、最適な入力値となる様にしてから測定シーケンスをやり直す。
逆に、点灯時データＶ_１ＯＮまたはＶ_２ＯＮがＡ／Ｄコンバータの最大入力値を超えている場合、集中制御装置（マイクロプロセッサユニット）９は、増幅率切替信号ＡＣＳにより増幅率を低減してから、測定シーケンスをやり直す。
これらは、測距距離Ｄ_Ｘが大きく変わると、受光できる反射光の強度が変わる為である。
【００７９】
（第８の実施例）
この出願の発明の第８の実施例について説明する。
この出願の発明の第８の実施例は、第１の実施例の合焦装置３における合焦レンズ位置検出手段３２を下記の合焦レンズ位置検出手段で置換したものに相当する。
光源（例えばレーザ）２の光軸から角度φだけ離れた方向の光（即ち側部光）の強さは、角φの減少関数である。
そのため、合焦レンズ位置検出用ポジションレンズ３２ＰＬの受光面が、前方に移動すれば（合焦レンズ３１のｘ座標が増大すれば）受光光量が増大し、後方に移動すれば（合焦レンズ３１のｘ座標が減少すれば）、受光量は減少する。即ち、合焦レンズ３１が前方に移動すれば、合焦レンズ位置検出用光電変換素子３２ＰＳの出力が増大し、合焦レンズ３１が後方に移動すれば、上記光電変換素子３２ＰＳの出力が減少する。
即ち、合焦レンズ位置検出手段３２の出力（位置検出信号）は、合焦レンズ３１のｘ座標の単調増加関数である。
それ故、上記単調増加関数の逆関数を求めることによって、合焦レンズ３１のｘ座標を求めることが出来る。
【００８０】
（その他の実施例）
その他の実施例について説明する。
その他の実施例は、前記の諸実施例中の諸事項と、以下の諸事項とを組み合わせることによって、生成される。
（イ）第１の実施例の合焦装置３の合焦レンズ位置検出手段３２における、合焦レンズ位置検出用光電変換器３２ＰＳは、多数の光電変換素子と位置検出用演算回路とで構成することが出来る。
（ロ）第１の実施例の振動ミラー形走査装置４における駆動手段は、圧電形電気機械変換器で構成することが出来る。
（ハ）第１の実施例の合焦装置３における合焦レンズ移動手段３３は、可動鉄片形として構成することが出来る。
（ニ）集中制御装置９をＡＳＩＣで構成することができる。
（ホ）各実施例における電子回路部分を、集中制御装置９と共にＩＣ化し、システム・オン・チップとすることが出来る。
【００８１】
【発明の効果】
この出願の発明は、以上の様に構成したから、下記（ａ）〜（１）の通り、顕著な作用効果を奏することが出来る。
（ａ）被読取物が遠点にあったり近点にあったりして読取距離が一定していない時でも、光学的情報を正確に読み取ることが出来る、超長読取深度の光学的情報読取装置を実現することが出来る。別言すれば、読取範囲の非常に大きな光学的情報読取装置を実現することが出来る。
（ｂ）小形、軽量、且低コストの合焦装置及び測距装置を実現することが出来る。これによって、全体としても小形、軽量、且低コストの光学的情報読取装置を実現することが出来る。
（ｃ）小形、軽量、且低コストの合焦装置及び測距装置を搭載した、手持式光学的情報読取装置を実現することが出来る。
【００８２】
（ｄ）合焦装置に対して、可変絞り装置を付加することによって、被読取物Ｔが近点にある時は、ビームウエストの細くなり過ぎによる解像度の上り過ぎを防止し、被読取物Ｔが遠点にある時は、ビームウエストの太くなり過ぎによる解像度の下がり過ぎを防止し、以って超長深度に亙って解像度を適正範囲に維持すると共に、被読取物Ｔが近点にある時に、近点の前後におけるビーム径の急激な増加を防止し、以って、走査ビームの偏向に伴う解像度の変動を防止して、Ｓ／Ｎ比を大幅に向上させた光学的情報読取装置を実現することが出来る。
（ｅ）光源の輝度（従って光量）を、距離測定信号及び／又は走査角信号の１次関数に基づいて、制御することによって、光電変換器７の受光光量を適正範囲に維持した、光学的情報読取装置を実現することが出来る。
（ｆ）前面に走査ミラー、後面に受光ミラーを有する振動ミラー形走査装置を使用することによって、即ち後面の受光ミラーを受光専用に利用することによって、受光口径を大きくし、従って受光光量を大きくした、光学的情報読取装置を実現することが出来る。
【００８３】
（ｇ）測距データを用いて、走査角を調節することによって、近点でも遠点でも必要な読幅を確保することが出来る。
（ｈ）測距データを用いて、レーザ光パワを制御することによって、受光利得および視認性の安定化を計ることが出来る。
（ｉ）測距データを用いて、受光利得を制御することによって、受光利得の安定化に寄与することが出来る。
（ｊ）測距データを用いて、走査速度を調節することによって、電気的アナログ信号の周波数帯域を制御することが出来る。
（ｋ）走査角データを用いて、レーザ光パワ又は受光利得を調節することによって、走査両側の受光光量の低下を補償することが出来る。
（１）走査角データを用いて、走査中央と両側との光路差による合焦物のずれを補正することが出来る。
【図面の簡単な説明】
【図１】この出願の発明による光学的情報読取装置の第１の実施例の全体構成を示す図である。
【図２】上記第１の実施例に使用する自動合焦装置の動作原理図である。
【図３】上記自動合焦装置の要部をなす光学的合焦ユニットの縦断面図である。
【図４】上記第１の実施例に使用する第１の測距装置の原理説明図である。
【図５】上記第１の実施例に使用する第２の測距装置の原理説明図である。
【図６】上記第１の実施例に使用する振動ミラー形走査装置の水平断面図及び垂直断面図である。
【図７】この出願の発明による光学的情報読取装置の第２の実施例に使用する可変絞り装置の動作原理図である。
【図８】この出願の発明による光学的情報読取装置の第３の実施例に使用する合焦装置及び可変絞り装置の動作原理図である。
【図９】合焦レンズ通過後のレーザビームの縦断面図である。
【図１０】固定絞り通過後のレーザビームのウエスト位置及び直径を示すグラフである。
【図１１】可変絞り通過後のレーザビームのウエスト位置及び直径を示すグラフである。
【図１２】この出願の発明による光学的情報読取装置の第４の実施例の全体構成を示す図である。
【図１３】上記第４の実施例に使用する走査式振動ミラー形走査装置を示す図である。
【図１４】合焦レンズによる光の集光位置を示す図である。
【図１５】合焦レンズ位置制御回路のブロック図である。
【図１６】この出願の発明の第７の実施例に使用する測距装置の入力回路のブロック図である。
【図１７】光源駆動回路のブロック図である。
【図１８】従来の自動焦点形スキャナの動作原理図である。
【図１９】従来の自動焦点形スキャナを利用した物流仕分けシステムの斜視図である。
【符号の説明】
１ 筐体
２ 光源
２Ｄ 光源駆動装置
３ 自動合焦装置（自動収束系）
３１ 合焦レンズ
３２ 合焦レンズ位置検出手段
３２ＰＬ 合焦レンズ位置検出用ポジションレンズ
３２ＰＳ 合焦レンズ位置検出用光電変換器（素子）
３２ＰＣ 合焦レンズ位置演算回路
３３ 合焦レンズ移動手段
３３Ｃ 可動線輪（励磁線輪）
３３ＣＤ 合焦レンズ位置駆動回路
３３Ｍ 永久磁石
３３Ｙ 継鉄（ヨーク）
３４ 合焦レンズ位置サーボ回路
３５ 電子的分圧器
３Ｂ 鏡筒（バレル）
３Ｈ 合焦レンズホルダ
３ＬＬ 合焦レンズ位置検出用レーザ光
３ＳＰ 支持バネ
３Ｕ 光学的合焦ユニット
４ 振動ミラー形走査装置
４１_１ 第１の振動ミラー（走査用ミラー）
４１_２ 第２の振動ミラー（受光用ミラー）
４２ 可動部
４２１ 可動磁石
４２２ 可動継鉄（ヨーク）
４２４ 磁性体
４２５ 回動軸
４６ ホルダ
４７ 固定継鉄
４７_１固定継鉄の対辺
４７_２固定継鉄の対辺
４８ 固定磁石
４９ 駆動線輪
５ 受光光学系
６ 測距装置（距離計）
６Ａ 差動増幅器
６Ｃ 測距用演算手段
６Ｌ 測距用受光レンズ
６Ｐ 測距用投光器
６Ｒ 測距用光電変換器
６ｓ 測距用光電変換素子
６Ｓ 測距用光電変換器
７ 光電変換器（光電変換器）
８ 信号処理部
９ 集中制御装置（例えばマイクロプロセッサユニット）
１０ 可変絞り装置
ＤＳ 距離信号
Ｉ 可変絞り
ＩＣ 可変絞り制御回路
ＬＢ レーザビーム
Ｍ 電動モータ
ＭＣ 合焦レンズ位置及び絞り回動角制御回路
ＭＳ レーザダイオードの監視信号
ｐ 光学的情報パターン（例えばバーコード記号）
ＳＢ 走査ビーム
Ｔ 被読取物（例えばラベル）
ＴＳ 温度センサ
ＶＤ 電子的分圧器[0001]
[Industrial application fields]
The invention of this application relates to a light beam scanning optical information reader for reading optical information using a light beam. In particular, the present invention relates to a variable focus light beam scanning optical information reader for accurately reading optical information from a near point to a far point over a long depth.
[0002]
[Prior art]
For example, in the physical distribution field, the distance between a fixed scanner and a label is generally not constant.
For this reason, the autofocus fixed scanner has been used award (see the Industrial Bar Association, July 1st, 1992, edited by Sato Asano, “The Future Bar Code System”, pages 203-204).
FIG. 18 is an operation principle diagram of such a conventional autofocus fixed scanner.
This type of autofocus fixed scanner includes a housing 1, a laser element 2, a converging optical system 3, a polygon mirror device 4, a light receiving optical system (not shown), and a distance meter 6. Yes.
The laser element 2, the converging optical system 3, the polygon mirror device 4, and the light receiving optical system are accommodated in the housing 1.
However, only the distance meter 6 is not housed in the housing 1 and is disposed outside.
[0003]
The converging optical system includes a converging lens 31, a converging lens moving mechanism (not shown), a converging lens position servo mechanism, and the like. The servo potentiometer 3P is a part of the convergent lens position servo mechanism.
The movable part of the servo potentiometer 3P is connected to a lens moving mechanism, and constitutes a movable part of the converging optical system together with the converging lens 31 and the lens moving mechanism.
The distance signal DS from the distance meter 6 is given to the servo potentiometer 3P. The converging lens position servo mechanism adjusts the position of the converging lens 31 so that its focal point matches the label surface.
[0004]
FIG. 19 is a schematic diagram showing an example of a physical distribution sorting system using a conventional autofocus fixed scanner.
This type of conventional distance meter 6 includes a distance measuring light projector 6P and a distance measuring light receiver 6R. The distance measuring light receiver 6R includes a plurality of light receiving elements arranged in the vertical direction as shown in the figure. Similarly, the distance measuring projector 6P is composed of a plurality of light emitting elements (not shown) arranged in the vertical direction.
Each article with the bar code symbol p is placed on a conveyor and passes between the distance measuring projector 6P and the distance measuring receiver 6R.
The distance meter 6 first determines the height h of the object on the conveyor by determining which of the light receiving elements that have detected the light shielding is the highest light receiving element._XCan be detected.
Fixed scanner height H_SIs known, so the distance D between the fixed scanner and the bar code symbol p_XCan be calculated by the following equation.
D_X= H_S-H_X                                      (1)
The other operations are the same as those in FIG.
[0005]
[Problems of the prior art]
The rangefinder 6 used in the autofocus fixed scanner in FIG. 19 has a large occupied volume so that the distance measuring projector 6P, the read object T, and the distance measuring light receiver 6R are in a straight line. Therefore, miniaturization is essentially difficult. In addition, since the distance measuring projector 6P and the distance measuring light receiver 6R are essentially fixed, it is impossible to mount them on a light beam scanning handheld scanner.
(Incidentally, in the field of television cameras in different industrial fields, focusing devices that use fluctuations in spatial frequency components (more specifically, harmonics in video signals (spatial frequency signals) when focus matching is achieved). A focusing device that utilizes the phenomenon that the wave component increases and decreases when it is out of focus alignment) is used. However, to be mounted on a hand-held scanner, the configuration is complicated and large. )
As described above, the movable portion in the converging optical system 3 in FIG. 18 includes the movable portion of the servo potentiometer 3P coupled to the converging lens 31 and the converging lens moving mechanism. It becomes. Accordingly, since the moving speed is reduced accordingly, it is difficult to follow this when the reading distance is changed suddenly.
In addition, the configuration is complicated and it is difficult to further reduce the size.
[0006]
OBJECT OF THE INVENTION
Therefore, the first object of the invention of this application is to be able to accurately read optical information even when the reading object is at a far point or a near point and the reading distance is not constant. An object of the present invention is to provide an optical information reader having a long reading depth. In other words, an optical information reader having a very large reading range is provided.
The second object of the invention of this application is to provide a compact, lightweight, and low-cost optical information reading device as a whole by realizing a compact, lightweight, and low-cost focusing device and distance measuring device. There is to do.
A third object of the invention of this application is to provide a hand-held optical information reading device equipped with a small-sized, lightweight, and low-cost focusing device and distance measuring device.
[0007]
The fourth object of the invention of this application is to prevent the resolution from being excessively increased at the near point and to prevent the excessive decrease at the far point by adding a variable aperture device. An object of the present invention is to provide an optical information reading apparatus capable of maintaining the resolution at an appropriate value.
A fifth object of the invention of this application is to provide an optical information reader capable of maintaining a received light amount at an appropriate value by controlling the light amount of a light source based on a distance signal and / or a scanning angle signal. Is to provide.
A sixth object of the invention of this application is to compensate for a change in the characteristics of the entire apparatus based on a change in the shape, dimensions, and physical properties of the constituent members due to a temperature change.
The seventh object of the invention of this application is to use a vibrating mirror type scanning device having a scanning mirror on the front surface and a light receiving mirror on the rear surface, that is, by utilizing the light receiving mirror on the rear surface exclusively for light reception. An object of the present invention is to provide an optical information reading apparatus which can be enlarged and therefore can increase the amount of received light.
[0008]
[Means for achieving the objectives]
In order to solve the above problems and achieve the above objects, an optical information reader according to the invention of this application is provided with:
A light source 2 that emits a light beam that scans the read object T;
A focusing device 3 for focusing the light beam emitted from the light source 2 on the object T to be read;
A vibrating mirror type scanning device 4 for periodically reflecting and deflecting the light beam in a horizontal plane;
A light receiving optical system 5 that condenses the reflected light reflected from the object T to be read at a predetermined position, and a photoelectric conversion that is disposed downstream of the light receiving optical system 5 and converts the reflected light into an electrical analog signal. Vessel 7;
A signal processing unit 8 connected to the output terminal of the photoelectric converter 7;
A distance measuring device 6 for measuring the distance from the vibrating mirror type scanning device 4 to the object T to be read;
A housing 1 that houses all or part of these elements;
Consisting of
The distance measuring device 6 and the focusing device 3 are connected so that a distance signal from the distance measuring device 6 is given to the focusing device 3 as a position command signal.
[0009]
  The focusing device 3 includes a focusing lens 31, a focusing lens position detection unit 32, a focusing lens moving unit 33, and a focusing lens position servo circuit 34. The focusing lens position detection means 32 does not use mechanical means such as a servo potentiometer, but uses optical means such as a focusing lens position detection position lens 32PL and a focusing lens position detection light receiver 32PS. It is a thing. A variable aperture device 10 can be added to the focusing device 3.
  The vibrating mirror type scanning device 4 includes a vibrating mirror 41 andElectromagneticA device integrally formed with the driving means can be used.
  The distance measuring device 6 does not use a projector dedicated to distance measurement, and is configured by a light receiving lens for distance measurement, a photoelectric converter for distance measurement, and an arithmetic circuit.
  An automatic luminance control device that compensates for variations in the amount of received light caused by variations in the distance between the vibrating mirror type scanning device 4 and the object to be read T can be added to the light source 2.
  A temperature compensation device can be added to the focusing device 3, the variable aperture device 10, and the automatic light source luminance control device.
[0010]
[Effects of the Invention]
The light beam emitted from the light source 2 is periodically reflected and deflected by the oscillating scanning mirror device 4 and repeatedly scanned on the object T to be read.
The reflected light from the read object T reaches the photoelectric converter 7 via the light receiving optical system 5 and is converted into an electrical analog signal. The electrical analog signal is converted into a digital signal in the signal processing unit 8 and below, and the optical information is decoded.
The distance measuring device 6 uses a distance measuring light-receiving lens 6L, a distance measuring photoelectric converter 6S, and a distance measuring arithmetic circuit 6C, and uses only reflected light derived from scanning light from the read object T, The distance from the vibrating mirror type scanning device 4 to the read object T is directly measured, and a distance measurement signal is output. The distance measuring device 6 does not use a projector dedicated to distance measurement, and the distance calculation arithmetic circuit 6C is simple, so it is small and lightweight.
[0011]
The focusing lens position detection means 32 of the focusing device 3 detects the position of the focusing lens 31, for example, during one scanning period of the light beam, and sends a focusing lens position detection signal to the focusing lens position servo circuit 34. give.
The focusing lens position servo circuit 34 of the focusing device 3 is constant when the difference between the focusing lens position command signal based on the distance measurement signal from the distance measuring device 6 and the focusing lens position detection means 32 becomes zero. A desired output current is given to the focusing lens moving means 33.
The focusing lens moving unit 33 of the focusing device 3 moves the focusing lens 31 along the optical axis based on the difference signal from the focusing lens position servo circuit 34, thereby focusing the scanning light beam. Can move from near point to far point over a very long depth. The focal point of the light beam is matched with the read object T.
Since the focusing device 3 does not use mechanical means such as a servo potentiometer, it is small and lightweight.
[0012]
The variable aperture device 10 relatively reduces the aperture diameter of the variable aperture I when the object T to be read is at the near point (thus, when the focusing lens is focused at the near point). Ω of light beam diameter 2 at emission_dIs made relatively small, the beam waist diameter at the near point is made relatively thick, and the beam diameter 2ω before and after the near point is made._ZCTo prevent sudden changes. Thereby, the variable aperture apparatus 10 has a beam waist diameter 2ω at the time of focusing on the near point of the light beam._OCAnd the beam diameter 2ω before and after the near point_ZCCan be prevented, and a decrease in the S / N ratio can be prevented.
Further, the variable aperture device 10 relatively increases the aperture diameter of the variable aperture I when the object T to be read is at the far point (that is, when the focusing lens is focused at the far point). Light beam diameter at the time of variable aperture emission 2ω_dThe beam waist diameter 2ω at the far point is made relatively large by_OFIs relatively small. Thereby, the variable aperture apparatus 10 has a beam waist diameter 2ω at the time of focusing the far point of the light beam._OFOf the S / N ratio can be prevented.
[0013]
【Example】
(First embodiment)
A first embodiment of the optical information reader according to the invention of this application will be described.
First, the overall configuration will be described generally.
FIG. 1 is a diagram showing an overall configuration of a first embodiment of the invention of this application.
In FIG. 1, 2 is a light source (for example, a laser diode), 2D is a light source driving circuit, 3 is a focusing device, 4 is a vibrating mirror type scanning device, 5 is a light receiving optical system, 6 is a distance measuring device, and 7 is a photoelectric converter. (Light receiver), 8 is a signal processing unit, 9 is a centralized control device (for example, a microprocessor unit), TS is a temperature sensor, and T is an object to be read. The description of the housing 1 is omitted.
[0014]
In the above-mentioned various processes, the light emitted from the light source 2 is the first mirror (scanning mirror) 41 of the focusing device 3 and the vibrating mirror type scanning device 4.₁, The object T to be read, the light condensing / deflecting means 5CP of the light receiving optical system 5, and the second mirror (light receiving mirror) 41 of the vibrating mirror type scanning device 4.₂It arrange | positions so that it can reach | attain the photoelectric converter (light receiver) 7 via. A signal processing unit 8 is connected to an output terminal of the photoelectric converter (light receiver) 7.
The distance measuring light receiving lens 6L of the distance measuring device 6 is a scanning mirror 41 of the vibrating mirror type scanning device 4.₁Is disposed at a position spaced apart by a distance d in the lateral direction.
The distance measuring device 6 includes a scanning mirror 41₁A distance signal DS is output by measuring a distance between the object T and the object T to be read (or a distance between the object T to be read and the light receiving lens 6L for distance measurement).
The focusing device 3 moves the focusing lens 31 in the direction of the optical axis based on the distance signal DS, and thus changes the distance between the light source 2 and the focusing lens 31 to focus on the object T to be read. Match.
During this time, the temperature characteristic of the entire system is compensated based on the output signal of the temperature sensor TS.
Further, the luminance of the light source 2 is controlled based on the output of the photoelectric converter 7 (or ranging photoelectric converter 6S) or based on the scanning angle signal.
Thus, the bar code symbol p on the read object T is read.
[0015]
Next, the partial configuration and partial operation of the first embodiment will be described.
(Focusing device of the first embodiment)
FIG. 2 is an operation principle diagram of the focusing device 3 used in the first embodiment, and FIG. 3 shows an optical focusing unit 3U that forms a main part of the focusing device 3 used in the first embodiment. FIG.
In FIG. 2, 31 is a focusing lens, 3H is a cylindrical focusing lens holder, 32 is a focusing lens position detecting means, 33 is a focusing lens moving means, 34 is a focusing lens position servo circuit (error amplifier), Reference numeral 35 denotes an electronic voltage divider.
The focusing lens 31 is made of a transparent material such as glass or synthetic resin.
The focusing lens position detection means 32 includes a focusing lens position detection position lens 32PL, a focusing lens position detection photoelectric converter 32PS, and a focusing lens position calculation circuit 32PC.
[0016]
The cylindrical focusing lens holder 3H penetrates the peripheral wall in a direction slightly inclined forward with respect to the light side passage (that is, slightly in the radial direction (radial direction)), for example, as shown in the drawing. A light side path) is formed, and a focusing lens position detecting position lens 32PL is embedded therein.
A focusing lens position detecting photoelectric converter 32PS is disposed at a condensing point by the focusing lens position detecting position lens 32PL, and a focusing lens position is connected to an output terminal of the focusing lens position detecting photoelectric converter 32PS. An arithmetic circuit 32PC is connected.
The output of the focus lens position detection photoelectric converter 32PS, that is, the output of the focus lens position detection means 32 becomes a focus lens position detection signal. The magnitude of the focus lens position detection signal is a function of the position of the focus lens holder 3H, and is therefore a function of the position of the focus lens 31.
[0017]
The focusing lens moving unit 33 includes a movable wire wheel drive circuit 33CD, a movable wire wheel 33C, and the like. The movable wire ring 33C is connected to the focusing lens holder 3H.
The focusing lens position servo circuit (error amplifier) 34 is configured by using, for example, an operational amplifier, and a constant desired output in a state where the combined voltage of the input voltage to the + terminal and the feedback voltage to the − terminal is substantially zero. It becomes current.
A focus lens position command signal is given to the + terminal of the focus lens position servo circuit 34 directly from the distance measuring device 6 or via the central control device (for example, a microprocessor unit) 9. Further, a focus lens position detection signal is given to the-terminal from the focus lens position detection photoelectric converter 32PS via the focus lens position calculation circuit 32PC. (The electronic voltage divider 35 will be described later.)
The output (current) of the focusing lens position servo circuit 34 is given to the movable line wheel drive circuit 33CD, and the output (current) of the movable line wheel drive circuit 33CD is given to the movable line wheel 33C.
When the difference signal between the focusing lens position command signal and the focusing lens position detection signal becomes zero, the movable wire ring 33C stops (stills stationary).
[0018]
FIG. 3 (a) is a longitudinal sectional view of an optical focusing unit 3U forming the main part of the focusing device 3 used in the first embodiment, and FIG. 3 (b) is a support spring used for this. FIG. 3C is a front view of 3SP, and is an operation principle diagram of a light receiving device for detecting a focus lens position.
In FIG. 3A, 2 is a light source (for example, laser), 31 is a focusing lens, 3H is a focusing lens holder, 3SP and 3SP are a pair of support springs, 3B is a lens barrel (barrel), and 32PL is in focus. Lens position detection position lens, 32PS is a focus lens position detection light receiver, 33C is a movable wire ring, 33M is a permanent magnet, and 33Y is a yoke.
[0019]
The focusing lens 31 is held by a focusing lens holder 3H, and the focusing lens holder 3H is supported and sandwiched by a pair of support springs 3SP and 3SP. The support springs 3SP and 3SP are, for example, the inner peripheral wall of the lens barrel 3B. It is fixed by the step provided in each.
The focusing lens holder 3H and the pair of support springs 3SP, 3SP together constitute a focusing lens support means 39.
For example, as shown in FIG. 3B, the support spring 3SP includes an outer ring, an inner ring, and several connecting portions (for example, three connecting portions) that connect both the rings. The spring action of the support spring 3SP is carried by, for example, three connecting portions. Each connecting portion is given an appropriate length according to a required spring force.
Since the focusing lens holder 3H is sandwiched between the pair of support springs 3SP, 3SP, it can be moved only in the optical axis direction. Therefore, the focusing lens 31 can also be completely moved only in the optical axis direction.
[0020]
The annular movable wire ring 33C is connected in series to the light source side of the focusing lens holder 3H.
Among the above elements, the focusing lens 31, the focusing lens holder 3H, the focusing lens position detection position lens 32PL, and the movable wire ring 33C jointly constitute a movable portion.
An annular permanent magnet 33M is coaxially disposed on the outer side of the movable wire ring 33C, and is substantially annular or a perforated dish (hereinafter simply referred to as “annular”) on the outer side of the annular permanent magnet 33M. A yoke 33Y is provided.
The substantially annular yoke 33Y is fixed to the inner peripheral wall of the lens barrel 3B.
[0021]
The annular permanent magnet 33M is magnetized, for example, in the radial direction (radial direction).
Since the yoke 33Y is made of iron or other ferromagnetic material, it efficiently guides the magnetic flux of the permanent magnet 33M to the movable wire ring 33C of the movable part.
The movable wire ring 33C receives a positive or negative force in the axial direction when energized. The force received is proportional to the product of the magnitude of the drive current and the magnitude of the magnetic field that intersects the drive current.
Therefore, the movable wire ring 33C moves forward or backward in the axial direction.
That is, when a driving current is supplied to the movable wire ring 33C, the focusing lens 31 moves forward or backward in the axial direction according to the sign of the driving current.
[0022]
The focus lens position detection position lens 32PL is embedded in the peripheral wall of the focus lens holder 3H forming a part of the movable portion. The position of the inner surface of the focusing lens position detecting lens 32PL is closer to the light source than the focusing lens 31, and its optical axis is more than the radial direction (radial direction) of the focusing lens holder 3H, as shown. It is tilted slightly forward. (However, the presence or absence of inclination is not an essential matter.)
As shown in the drawing, a through-hole is formed in the peripheral wall portion of the lens barrel 3B that intersects the optical axis (extension line) of the focusing lens position detection position lens 32PL, and is close to the outer peripheral wall of the lens barrel 3B. A focusing lens position detecting photoelectric converter 32PS is disposed.
[0023]
The cross-sectional shape of the through-hole of the lens barrel 3B and the shape of the light receiving surface of the focusing lens position detecting photoelectric converter 32PS are both vertically long, and their longitudinal dimensions are the same as those of the focusing lens position detecting position lens 32PL. It must be large enough to completely cover the moving range. (However, the focusing lens position detecting photoelectric converter 32PS does not have to be parallel to the moving direction of the focusing lens position detecting position lens 32PL (the optical axis direction of the focusing lens 31).)
The laser light (side light) that has reached the inner surface of the focus lens position detection position lens 32PL is led out of the focus lens holder 3H, as in the focus lens position detection laser light 3LL of FIG. The light is incident on the light receiving surface of the focus lens position detecting light receiver 32PS. The focusing lens position detection position lens 32PL is designed so that the condensing point of the laser beam 3LL coincides with the light receiving surface of the focusing lens position detection photoelectric converter 32PS.
[0024]
Among the above-described elements, the lens barrel 3B, the focusing lens position detecting light receiver 32PS, the permanent magnet 33M, and the yoke 33Y jointly constitute a fixed portion.
Then, the fixed portion, the movable portion, and the support spring 3SP together constitute an optical focusing unit 3U.
In this embodiment, the light source 2 is disposed inside the lens barrel 3B and in the inner space of the movable wire ring 33C and is supported by a yoke 33Y as shown in the figure.
As a result, the axial dimension is reduced.
[0025]
A functional relationship between the position of the focusing lens 31 and the light collection position of the focusing lens 31 will be described.
FIG. 14 is a diagram illustrating a light condensing position by the focusing lens 31.
Focal length f₀As shown in the drawing, the focusing lens 31 is separated from the light source 2 by a distance f.₀When placed at the position, the light emitted from the focusing lens 31 becomes parallel light.
Therefore, this position can be used as a reference position for the focusing lens 31. Alternatively, the x-axis is taken in accordance with the optical axis direction of the focusing lens 31, and this position can be set as the origin (x = 0).
When the focusing lens 31 moves away from the reference position (x = 0) by Δf to the side opposite to the light source (the object T to be read), the laser light is f from the focusing lens.₂Position (x = f₂).
[0026]
F for ease of viewing₀+ Δf = f₁The above relationship is the lens formula
(1 / f₀) = (1 / f₁) + (1 / f₂)
As well known. If the above equation is modified, the following equation is obtained.
f₂= (1 / Δf) f₀ ²+ F₀                                  (2)
That is, f₂Is proportional to (1 / Δf).
The internal optical path length from the focusing lens 31 to the distance measurement origin is L, and the distance from the distance measurement origin to the barcode is D._xThen f₂Is given by:
f₂= D_x+ L (3)
From the equations (2) and (3), the following equation is obtained.
Δf = f₀ ²/ (F₂-F₀) = F₀ ²/ (D_x+ L-f₀(4)
Δf in equation (4) is the distance signal D_xIt can be interpreted as a focusing lens position command signal based on the above. This Δf is hereinafter referred to as Δf_cWrite.
[0027]
The focusing lens position detecting photoelectric converter 32PS and the focusing lens position control circuit 34 will be described.
FIG. 15 is a side view of the focus lens position detecting photoelectric converter 32PS and a block diagram of the focus lens position control circuit 34.
In FIG. 15, 32PS is a focus lens position detection photoelectric converter, 34 is a focus lens position control circuit, 33C is a movable wire wheel, 33CD is a movable wire wheel drive circuit, and 9 is a central control device (for example, a microprocessor unit). It is.
The operational characteristics of the focus lens position detection photoelectric converter 32PS are as follows.
When the spot light comes to the light receiving surface of the focusing lens position detecting photoelectric converter 32PS, the current I is connected to the A end._aCurrent I at the B end_bIs generated. Current I_aAnd I_bThe size of varies depending on the position of the spot light.
Taking the x ′ axis along the longitudinal direction of the focusing lens position detecting photoelectric converter 32PS, the A end is the origin (x ′ = 0), the B end is x ′ = W, and for simplicity, the intensity of the spot light Is constant, the current I_a, I_bThe sizes of are as follows.
I_a= P (W−x ′), I_b= Px '(5)
However, p is a proportional constant.
[0028]
Since the focusing lens position detecting photoelectric converter 32PS is fixed to the lens barrel 3B of the optical focusing unit 3U as shown in FIG. 3A, it does not move.
On the other hand, since the focus lens position detection position lens 32PL is connected to the movable portion (for example, movable line transfer 33C) of the optical focus unit 3U as described above, as the focus lens 31 moves. Moving.
As shown in FIG. 3A, the focusing lens position detecting position lens 32PL takes in unnecessary light (side light that does not enter the focusing lens 31) from the laser light source 2, condenses it, and focuses the focusing lens position. A laser beam 3LL for detection is formed. The light spot (or light stripe) is applied to the light receiving surface of the focusing lens position detecting photoelectric converter 32PS.
Thus, the light spot (or light stripe) collected by the focus lens position detection position lens 32PL moves on the focus lens position detection photoelectric converter 32PS as the focus lens 31 moves. If the moving distance of the focusing lens 31 is Δf and the moving distance of the light spot (or light stripe) is Δf ′, the following equation is approximately established.
Δf ′ = aΔf (6)
However, a is a proportionality constant.
The above-described proportionality constant a is a value close to approximately 1 as is apparent from FIG.
[0029]
Now, when Δf = 0 (thus, x = 0), x ′ = g.
That is, when the focusing lens 31 is at the reference position (x = 0), the light spot of the focusing lens position detecting laser beam 3LL condensed by the focusing lens position detecting position lens 32PL is the focusing lens position. A point (position) that hits the detection photoelectric converter 32PS is set to x ′ = g.
When x = Δf, x ′ = g + Δf ′.
That is, when the focusing lens 31 is moved from the reference position by Δf to the reading object T side, the light spot of the focusing lens position detection laser beam 3LL condensed by the focusing lens position detection position lens 32PL is A point (position) that hits the focusing lens position detecting photoelectric converter 32PS is set to x ′ = g + Δf ′ as shown in FIG.
Then, the following equation is obtained based on equations (5) and (6).

However, W is the total light receiving width of the focusing lens position detecting photoelectric converter 32PS.
This equation holds even if the amount of incident light changes.
[0030]
If equation (7) is modified, the following equation is obtained.
Δf = [{WI_b/ (I_a+ I_b)}-G] / a (8)
Δf according to equation (8) is a focusing lens position measurement signal. In this case, Δf is expressed as Δf_mWrite.
In principle, the focusing lens position command signal Δf according to the equation (4)_cAnd the focusing lens position measurement signal Δf according to the equation (8)_mCan be applied to each input terminal of a differential amplifier (error amplifier) in the focusing lens position servo circuit 34 of FIG.
When the focusing operation starts, Δf increases, and therefore Δf_mIncreases but Δf_mIs Δf_cThe in-focus lens 31 stops at the point where it matches. Then, the focusing operation ends.
[0031]
Returning to FIG. 15, the electronic voltage divider 35 and the error amplifier E (that is, the focusing lens position servo circuit 34) will be described.
Current signal I from terminal A_a, And current signal I from the B end_bAre converted into voltage signals, respectively, and V_a, V_bIt becomes.
Voltage signal V from A end_aIs applied to the adder A and the voltage signal V from the B end_bIs applied to the adder A and the-of the error amplifier E.
In the adder A, the sum signal V_a+ V_bIs made.
Sum signal V_a+ V_bIs applied to the first input terminal of the electronic voltage divider VD.
Equation (7) is the voltage signal V_a, V_bAnd V_a+ V_bCan be rewritten as follows.
V_b/ (V_a+ V_b) = (AΔf_c+ G) / W (9)
V_b= (V_a+ V_b) (AΔf_c+ G) / W (10)
Equation (10) holds even if the amount of incident light changes.
The central controller (eg microprocessor unit) 9 sends a partial pressure control signal DCS to the second input terminal of the electronic voltage divider VD.
The voltage division ratio by the voltage division control signal DCS is (aΔf_c+ G) / W.
The electronic voltage divider VD is the sum signal V_a+ V_bAnd the partial pressure ratio (aΔf_cA value obtained by multiplying + g) / W is output.
[0032]
  The output of the electronic voltage divider VD and the actual V_bAnd error amplifier E (that is, focusing lens position servo circuit 3)4The input is applied and the output is applied to the movable wire ring 33C.
  When the in-focus operation starts, Δf ′ increases as Δf increases, so that the actual V_bIncreases, but V_b(V_a+ V_b) (AΔf_cThe focusing lens 31 stops when it matches + g) / W. Then, the focusing operation ends.
  Thus, the focusing lens 31 is moved to a position (x = Δf) designated by the central controller (for example, the microprocessor unit) 9._c) Can be held.
  The focusing operation based on equations (4) and (8) (see FIG. 2) and the focusing operation based on equation (10) (FIG. 15) are essentially equivalent. However, the latter requires fewer operations.
  The electronic voltage divider VD in FIG. 15 includes a digital / analog converter A / D, E²POT (psychone) can be used.
  A dedicated light source for detecting the focus lens position is not necessary.
[0033]
(Ranging device of the first embodiment)
A first distance measuring device used in the first embodiment will be described.
FIG. 4 is a diagram illustrating the principle of the first distance measuring device used in the embodiment.
4A, 2 is a light source, 41 is a vibrating mirror, T is an object to be read, 6L is a light receiving lens for distance measurement, 6s is a photoelectric sensor for distance measurement with a small diameter, and a is the scanning center of the vibration mirror 41. Line (ie center line in the reading direction), b₂Is a light receiving center line of the ranging light receiving lens 6L.
There is no need for a dedicated projection light source.
[0034]
For convenience of explanation,
Scan center line a₁And light receiving center line b₂The distance between and
A distance between the vibrating mirror 41 and the object T to be read (or a distance between the light receiving lens 6L for distance measurement and the object T to be read) is D._x,
Scan center line a₁And A, the intersection of
Light receiving center line b₂And B, the intersection of
A reflected light beam from the point A toward the light receiving lens 6L for distance measurement is a₂,
B rays from the oscillating mirror 41 toward the point B₁,
The angle at which the line segment AB is viewed from the center point of the vibrating mirror 41 (scanning center line a₁And ray b toward point B₁The angle between the angle and the swing angle is θ
And
For simplicity, scan center line a₁And the object T to be read are orthogonal to each other (that is, the reading center line a₁And the read object T are orthogonal to each other).
Since the value of e is given, if the swing angle θ can be measured, the distance D to the read object T_XIs given by:
D_X= E / tan θ (11)
[0035]
Since the photoelectric conversion element 6s for distance measurement has a small diameter, the light receiving center line b₂Rays coming off the point (eg ray a coming from point A₂) Is not received by the distance measuring photoelectric conversion element 6s as shown in the figure.
Accordingly, the light beam received by the distance measuring photoelectric conversion element 6s is the light receiving center line b.₂Only rays that come along.
Time t when the scanning beam passes through point A_ACan be determined based on the scanning synchronization signal. Time point t when the scanning beam passes through point B_BCan be detected by detecting the output maximum time because the output of the ranging photoelectric conversion element 6s becomes the maximum. A known means is used for detection of the output maximum time point.
[0036]
Time t_AAnd time t_BT is the time difference between_dThen, the angle (swing angle) θ at which the line segment AB is viewed from the center point of the oscillating mirror 41 is the time difference t_dIs proportional to That is,
θ = kt_d                                          (12)
However, k is a proportional constant determined by the scanning speed.
Therefore, the distance D to the read object T_xIs given by:
D_X= E / tan (kt_d) = E cot (kt_d(13)
FIG. 4B shows a case where the read object T in FIG. 4A is rotated about the point A counterclockwise by an angle ψ. A broken line T ′ indicates a current position after rotation of the reading object.
Error D due to rotation of angle ψ_X'Occurs. D_X′ Is given by:
D_X′ = E tanψ (14)
If the angle ψ (radian) is small, D_XSince '≈eψ≈0, there is no possibility (or fear) of hindering the focus alignment.
[0037]
(Vibrating mirror type scanning device of the first embodiment)
The vibrating mirror type scanning device 4 used in the first embodiment will be described.
6A and 6B are a horizontal sectional view and a vertical sectional view of the vibrating mirror type scanning device.
In FIGS. 6A and 6B, 41₁Is the first reflecting mirror (scanning mirror), 41₂Is a second reflecting mirror (light receiving mirror), 42 is a movable part, 46 is a holder, 47 is a fixed yoke (yoke), and 49 is a drive winding.
The movable part 42 includes a movable part main body and a rotating shaft 425, and the movable part main body has a plate shape, a rod shape, or a three-dimensional shape, and includes two movable magnets 421 and 421 and a movable yoke 422. To do.
First reflection mirror 41₁And the movable part main body and the second reflection mirror 41₂Is integrally formed.
[0038]
  When the drive winding 49 is not energized, the movable body stops at the position shown in the figure.
  When the movable body is released by rotating it by an appropriate angle from the stationary position, an attractive force (magnetic spring force) is generated between the movable magnet 421 and the yoke 47, so that the movable body 42 starts free reciprocating vibration. .
  When the drive winding 49 is energized, a positive or negative couple acts on the movable magnet 421 because the drive current intersects the magnetic field of the movable magnet 421. As a result, the movable body 42 starts forced vibration.
  First reflection mirror 41₁Periodically reflects and deflects the light beam coming from the focusing device 2. Second reflection mirror 41₂The reflected light arriving from the flying point (light moving point) on the object T to be read via the condensing and deflecting means 5CP is periodically reflected and deflected and emitted toward the photoelectric converter 7. .
  The condensing and deflecting unit 5CP may be configured such that the condensing lens and the reflecting prism are integrally formed as shown in the drawing, or the condensing lens and the reflecting prism may be configured separately from each other.
(Note that the above vibrating mirror type scanning device 4 is disclosed in Japanese Patent Application No. 6-87157 related to the application of the applicant of the present invention.(Japanese Patent Laid-Open No. 7-261109)In the specification and drawings. )
[0039]
(Light-receiving optical system of the first embodiment)
The light receiving optical system 5 used in the first embodiment will be described.
Returning to FIG. 1, 5CP is a condensing / deflecting means, which has both condensing action and deflecting action.
Condensing and deflecting means 5CP and second reflecting mirror 42₂Together with (see FIG. 6A), the light receiving optical system 5 is configured.
The condensing and deflecting unit 5CP collects the reflected light coming from the flying point (light moving point) on the read object T and converts the traveling direction of the collected reflected light to generate the second reflection. Mirror 41₂It injects towards. Second reflection mirror 41₂The incident reflected light is periodically reflected and deflected to enter the photoelectric converter 7.
In this embodiment, the amount of received light can be increased by enlarging the light receiving aperture of the condensing and deflecting means 5CP.
[0040]
(Light source of the first embodiment)
In FIG. 1, 2 is a light source. As the light source 2, for example, a visible light semiconductor laser that emits a visible light beam, or a surface-emitting type LED that uses a mesa structure with a very small diameter is used.
A condensing lens can be incorporated in the light source 2. However, the condensing lens must preserve the side light.
[0041]
(Light source driving circuit of the first embodiment)
The light source driving circuit of the first embodiment will be described.
Since the light projection from the light source 2 is a beam-like light beam, the optical power incident on the barcode does not change even if the distance between the barcode and the scanning device changes. The reflected light from the barcode surface incident on the light receiving lens changes depending on the distance. When the light receiving aperture is constant, the amount of received light is inversely proportional to the square of the distance from the barcode.
If the light output is controlled based on the distance data obtained by distance measurement, the amount of received light can be kept constant even if the distance from the barcode changes. (However, the maximum output power may be limited by light emission safety standards, etc.)
[0042]
FIG. 17 is a block diagram of the light source driving circuit 2D. This figure shows a case where a laser diode is used as the light source.
A part of the light emitted from the laser diode LD is incident on the monitoring photodiode MPD for observing the light output. The monitoring photodiode MPD generates a monitor current proportional to the light emission output of the laser diode LD. The monitor current is converted into a voltage signal EC by the resistor R and input to the negative terminal of the error amplifier E.
The light output control voltage LPCS is input to the + terminal of the error amplifier E.
The monitor voltage EC is compared with the light output control voltage LPCS by the error amplifier E, and the light emission output of the laser is controlled so as to be the same voltage.
The light output control voltage LPCS is obtained by, for example, converting a light output control signal (logical value) sent from a central control device (for example, a microprocessor unit) 9 into an analog amount by a DA converter D / A. .
[0043]
(Temperature compensation device of the first embodiment)
In FIG. 1, TS is a temperature sensor. Temperature compensation of the focusing device 3 and the light source driving circuit 2D can be performed using the temperature measurement signal of the temperature sensor TS.
As the temperature sensor TS, a temperature sensitive element (eg, a thermistor, a diode, etc.) with known temperature characteristics can be used.
Since the thermistor is an element whose resistance value changes with temperature, the resistance value is converted into a voltage value by a resistance voltage conversion circuit, and the voltage value is converted into a digital signal by an A / D converter. (For example, a microprocessor unit) 9
For example, a signal proportional to the temperature measurement signal can be added (subtracted) to the focusing lens position servo circuit 34 of the focusing device 3. As a result, it is possible to prevent the focal point from fluctuating due to temperature fluctuations. As a result, a plastic lens can be used as the focusing lens.
Further, for example, another signal proportional to the temperature measurement signal can be added (subtracted) to the light source driving circuit 2D. This eliminates the influence of temperature fluctuations on the amount of received light.
[0044]
(Second embodiment)
A second embodiment of the optical information reading device according to the invention of this application will be described.
The second embodiment corresponds to the first embodiment with a variable aperture device added.
FIG. 7A is an operation principle diagram of the first variable aperture device used in the second embodiment.
In FIG. 7A, 2 is a light source, 31 is a focusing lens, I₁Is a variable circular aperture, and IC is an aperture control circuit.
The above variable circular aperture I₁The aperture control circuit IC and a circular aperture drive mechanism (not shown) jointly constitute the first variable aperture device 10.
Variable circular aperture I₁The structure and function of the circular aperture driving mechanism are the same as those known in the field of cameras, for example. Variable circular aperture I₁The shape of the aperture does not change even when the aperture diameter changes, and is always circular.
The aperture control circuit IC receives the distance signal from the distance measuring device 6 directly or via the microprocessor 9, converts it into an aperture control signal, and applies it to the circular aperture drive mechanism.
The circular diaphragm driving mechanism is configured to change the variable circular diaphragm I based on the diaphragm control signal.₁Adjust the aperture diameter of.
Variable circular aperture I after rotation adjustment₁The aperture diameter is a linear function of the distance signal.
[0045]
FIG. 7B is an operation principle diagram of the second variable aperture device used in the second embodiment.
In FIG. 7B, 2 is a light source, 31 is a focusing lens, I₂Is a variable parallelogram diaphragm, and IC is a variable parallelogram diaphragm control circuit.
The above variable parallelogram iris I₂The aperture control circuit IC and a parallelogram aperture drive mechanism (not shown) constitute the second variable aperture device 10.
Variable parallelogram iris I₂The structure and function of the parallelogram diaphragm drive mechanism are the same as those known in the field of cameras, for example. Variable parallelogram iris I₂Only the lateral width (short side length) of the opening of is changed.
The aperture control circuit IC receives the distance signal from the distance measuring device 6 directly or via the microprocessor 9, converts it into an aperture command signal, and applies it to the parallelogram aperture drive mechanism. The parallelogram diaphragm driving mechanism is configured to change the variable parallelogram diaphragm I based on the diaphragm command signal.₂Adjust only the width (short side length) of the opening.
Variable circular aperture I after rotation adjustment₂The aperture diameter is a linear function of the distance signal.
[0046]
The usefulness of the variable aperture device will be described in more detail.
FIG. 9 is a longitudinal sectional view of the laser beam after passing through the focusing lens. However, the laser beam has a Gaussian distribution.
In FIG. 9, reference numeral 31 denotes a focusing lens, and ω_dIs the radius of the laser beam at the exit point of the focusing lens 31 (= radius of the focusing lens), ω_OIs the beam waist radius, Z_OIs the distance from the exit point of the focusing lens 31 to the beam waist position.
At this time, the beam waist radius ω_OAnd diameter 2ω_OIs represented by the following equation.
ω_O= ΛZ_O/ (Πω_d(15)
2ω_o= 2λZ_O/ (Πω_d(15 ')
Where λ is the wavelength of the laser beam.
[0047]
  Now, the radius ω of the laser beam at the exit point of the focusing lens 31_dAnd the wavelength λ is also constant, the beam waist radius ω_o(And diameter 2ω_o) Is the beam waist distance Z_oIs a linear function of
  If the equation (15 ′) is graphed, the straight line 1 in FIG. 10 is obtained.
  However, since FIG. 10 shows three coordinate systems for convenience,straightLine 1 is the distance Z_oThe horizontal axis, beam waist diameter 2ω_oThe verticalAxis andCoordinate system (Z_o-2ω_oNote that this is a straight line on the coordinate system.
  As is clear from the straight line 1 in FIG._oFIs at the beam waist diameter 2ω_oFIs thick, beam waist position is near Z_ocWhen the beam diameter is 2ω_ocIs thin.
[0048]
Beam waist radius ω_OAs is clear from equation (8), the wavelength λ of the laser light source and the aperture of the lens (2ω_d) And beam waist position Z_ODetermined by selection.
In general, the predetermined far point Z_OFBeam waist radius ω when automatically focused on_OIs the desired value ω_OFΩ_dSelect.
Then, the near point Z_OCWhen automatically focused on, the beam waist diameter is 2ω_OCAs can be seen from the straight line 1 in FIG. 10, the beam waist is much smaller (thinner) than the desired beam waist diameter. That is, (Z_OF/ Z_OC1) and finish. As a result, the near point Z_OCIf the optical resolution of the signal is excessively higher than necessary, it is possible to detect and perform operations other than the read data (soil on the paper, uneven printing, etc.) and deteriorate the signal S / N.
[0049]
However, in the second embodiment, as shown in FIG. 7, the variable stop I is disposed in front or rear of the focusing lens 31, so that the focusing lens 31 is moved to the near point Z._OCAt the same time, the variable aperture I is automatically adjusted to_dBy reducing the beam waist radius ω_OCThus, the above-described deterioration of the S / N ratio can be prevented.
FIG. 11 is a graph showing the waist position and diameter of the laser beam after passing through the variable aperture. The minimum value of the curve 2 in FIG._OCBeam waist diameter 2ω when focused on_OCIs much larger (thicker) than that of curve 2 in FIG. 10, and a desired value (required value) 2ω_OFYou can see that you are approaching.
[0050]
Returning to FIG. 9, ω_ZIs the radius of the laser beam at a point Z away from the beam waist position.
Radius ω of the above laser beam_ZAnd diameter 2ω_ZIs given by:
ω_Z ²  = Ω_O ²{1+ (λ / (πω_O ²))²Z²} (16)
(2ω_Z)²= 4ω_O ²{1+ (λ / (πω_O ²))²Z²} (16 ')
Beam waist is an arbitrary near point Z_OCIf the equation (9 ′) is graphed, the curve 2 in FIG. 10 is obtained. In FIG. 10, as described above, three coordinate systems are shown for convenience, but the curve 2 indicates the near point Z._OCIs the origin and the near point Z_OCDistance Z from the horizontal axis, laser beam diameter 2ω_ZIs a coordinate system with the vertical axis (ie, Z-2ω_ZIt is a curve on the coordinate system.
[0051]
Also, the beam waist is an arbitrary far point Z_OFWhen the equation (16 ′) is graphed, the curve 3 in FIG. 10 is obtained. Curve 3 is the far point Z_OFIs the origin and the far point Z_OFDistance Z from the horizontal axis, laser beam diameter 2ω_ZIs a coordinate system (ie, Z-2ω_ZA straight line on the coordinate system.
(Incidentally, the diameter of the laser beam 2ω_ZCan be expressed as a function of the spatial coordinate z with the exit point of the focusing lens 31 as the origin, for example, the following equation may be substituted into equation (16 ′).
(Beam waist is near Z_OCZ = z-Z_OC      (17)
(Beam waist is far point Z_OFZ = z-Z_OF    (17 ')
However, z = 0 (origin) is the exit point of the focusing lens 31, and z = Z_OCIs the near point, z = Z_OFIs a far point. )
[0052]
As is clear from curve 2 in FIG._OCWhen automatically focusing on the beam diameter 2ω_ZIs near point Z_OCTherefore, the accuracy of automatic focus control needs to be improved. However, the distance z (Z from the focusing lens 31 to the read object)_OC+ Z) changes at a fast cycle as the scanning beam is deflected, and also changes at a fast cycle when the surface of the object to be read is curved. Therefore, it is difficult to make the autofocus control operation follow such a change. It is. Therefore, the optical resolution is likely to change.
[0053]
However, in the second embodiment, as described above, since the variable stop I is disposed in front or rear of the focusing lens 31 as shown in FIG._OCAt the same time, the variable iris I is automatically adjusted_dBy reducing the beam waist radius ω_OCIs relatively large (thick), the variable Z in the curly braces {} on the right side of the equations (9) and (9 ′)²Coefficient of
(Λ / (πω_OC ²))²
Becomes smaller, so the near point Z_OCΩ before and after_Z ²Changes slowly, the beam radius ω_ZChange (rise) also slows down.
According to FIG. 11, it can be seen that the curvature of curve 2 is much smaller than that of curve 2 of FIG.
In short, the second embodiment avoids a situation in which the beam waist diameter at the near point becomes excessively thin due to the use of the automatic focusing device, and the optical path length caused by the beam scanning or the curvature of the surface of the object to be read. A change in optical resolution based on the change can be reduced.
The remaining items of the second embodiment are the same as those of the first embodiment.
[0054]
(Third embodiment)
A third embodiment of the optical information reader according to the invention of this application will be described.
In the third embodiment, the focusing device in the first embodiment is replaced with the following, and the following variable aperture device is added.
FIG. 8 is an operation principle diagram of the focusing device 3 and the variable aperture device used in the third embodiment.
In FIG. 8, 2 is a light source, 3H is a cylindrical focusing lens holder, FS is a feed screw, g₁Is the first gear, g₂Is a second gear, M is an electric motor, 33 is a focusing lens position moving means, I₃Is a rotatable rectangular aperture, and MC is a focusing lens position control circuit / rectangular aperture rotation angle control circuit.
[0055]
The feed screw FS is formed as a male screw on the outer peripheral surface of the cylindrical focusing lens holder 3H, and is screwed into a female screw formed on the inner peripheral surface of the lens barrel 3B (not shown). (Alternatively, this relationship may be reversed, and a female screw may be formed on the focusing lens holder 3H side and a male screw on the lens barrel 3B side.) Configure.
First gear g₁Is connected to the electric motor M through a rotating shaft, and the second gear g₂Are coaxially coupled to one end surface (or outer peripheral surface) of the cylindrical focusing lens holder 3H. Second gear g₂Is provided with a through hole for allowing the light beam to pass therethrough. Both gears g₁, G₂Jointly with the gear mechanism (g₁, G₂).
(Second gear g₂And the cylindrical focusing lens holder 3H can be configured integrally or separately. )
[0056]
Feed screw mechanism FM and gear mechanism (g₁, G₂), The electric motor M, and the focusing lens position control circuit / rectangular aperture rotation angle control circuit MC together constitute the focusing lens position moving means 33.
The focusing lens position control circuit / rectangular aperture rotation angle control circuit MC receives a distance signal from the distance measuring device 6 directly or via the microprocessor 9, and receives the focusing lens position command signal / rectangular aperture rotation angle. It is converted into a command signal and applied to the electric motor M.
The focusing lens position control command signal and the rectangular aperture rotation angle control signal are a linear function of the distance signal.
The electric motor M rotates according to the focusing lens position control signal. The rotational movement of the electric motor M is the gear mechanism (g₁, G₂) Is transmitted to the cylindrical focusing lens holder 3H, and is converted into an axial linear motion by the feed mechanism FM.
The position of the focusing lens 31 after the movement adjustment is a linear function of the distance signal.
(Gear mechanism (g₁, G₂) And the pitch of the lead screw FS are reflected in the proportionality coefficient of the distance signal. )
[0057]
Rotatable rectangular aperture I₃Is made of a rotatable plate and has a rectangular opening in the center. Rotatable rectangular aperture I₃Is the second gear g₂Alternatively, they are concentrically coupled to the focusing lens holder 3H. (The three are configured as one body or separate bodies).
Rotatable rectangular aperture I₃And gear mechanism (g₁, G₂), The electric motor M, and the focusing lens position control circuit / rectangular aperture rotation angle control circuit MC together form a rotatable rectangular aperture device 10.
Since the cross section of the light beam from the semiconductor laser light source is originally vertically long, the rotatable rectangular diaphragm I₃The cross-sectional shape of the incident light beam to the rotary rectangular aperture I₃It is possible to make it the same size as the opening shape dimension.
[0058]
At this time, the rotating rectangular aperture I₃The cross-sectional shape dimension of the light beam passing through₃Depending on the rotation angle, the minimum is when the rectangular opening is horizontal, and the maximum when the rectangular opening is vertical. That is, the rotatable rectangular aperture I₃The cross-sectional shape of the light beam that has passed through is the same as the shape formed by the common portion (overlapping portion) of the light beam cross-section and the aperture cross-section.
Rotatable rectangular aperture I₃Is the gear mechanism (g₁, G₂) Is rotated according to the lens position control signal and the rectangular aperture rotation angle control signal from the focusing lens position control circuit and rectangular aperture rotation angle control circuit MC.
The position (angle) of the rectangular opening after the rotation adjustment is a linear function of the distance signal.
(Gear mechanism (g₁, G₂) Tooth number ratio is reflected in the proportional constant of the distance signal. )
The usefulness of the variable aperture device used in the third embodiment is the same as that in the second embodiment.
The remaining items of the third embodiment are the same as those of the first embodiment.
[0059]
(Fourth embodiment)
A fourth embodiment of the optical information reader according to the invention of this application will be described.
The fourth embodiment corresponds to the one obtained by replacing the vibrating mirror type scanning device and the light receiving optical system in the first embodiment with the following.
In FIG. 12, it is a figure which shows the whole structure of the 4th Example.
In FIG. 12, 4 is a vibrating mirror type scanning device, and 5 is a light receiving optical system.
The remaining elements 2-3 and 6-9 are the same as the elements in FIG.
[0060]
(Vibrating mirror type scanning device of the fourth embodiment)
3A and 3B are diagrams showing a vibrating mirror type scanning device used in the fourth embodiment, where FIG. 3A is a horizontal sectional view, FIG. 3B is a front view, and FIG. 3C is a side view.
In FIG.₁Is a reflection mirror, 42 is a movable part, 46 is a holder, 47 is a fixed yoke, and 49 is a drive winding.
A difference in configuration of the fourth embodiment with respect to the first embodiment will be described.
The shape of the fixed yoke 47 is substantially U-shaped. The substantially U-shape is a shape formed by deleting one side of a substantially mouth shape.
A pair of opposite sides of the fixed yoke 7 to 47₁, 47₂Is typically linear, but can also be a gentle curve.
[0061]
The movable part 42 includes a movable part main body and a rotation shaft 425.
The movable part body is a pair of opposite sides 47 of the fixed yoke 47.₁, 47₂And between the front and the front (close to the open end).
The movable part main body and the fixed yoke 47 constitute a substantially mouth-shaped magnetic circuit.
The rotation shaft 425 is disposed perpendicular to the plane including the fixed yoke 47.
Each of the drive windings 49, 49 is a pair of opposite sides 47 of the fixed yoke 47.₁, 47₂Wound around the front of the.
Only reflection mirror (scanning mirror) 41₁Is fixed to the front surface of the movable portion 42.
The remaining configuration of the fourth embodiment is the same as that of the first embodiment.
[0062]
(Light-receiving optical system of the fourth embodiment)
The light receiving optical system used in the fourth embodiment will be described.
Returning to FIG. 12, the light receiving optical system 5 includes a conventional condenser lens.
The reflected light that has passed through the condenser lens 5 enters the photoelectric converter 7 directly and without any intervention.
The remaining items of the fourth embodiment are the same as those of the first embodiment.
[0063]
(Fifth embodiment)
A fifth embodiment of the optical information reader according to the invention of this application will be described.
In the fifth embodiment, the light receiving optical system 5 in the fourth embodiment is moved to the vicinity of the focusing device 3, and the reflection mirror of the vibrating mirror type scanning device is also used as a light receiving mirror. It corresponds to a thing.
In the fifth embodiment, the amount of received light is slightly reduced compared to the first to fourth embodiments.
The remaining items of the fifth embodiment are the same as those of the fourth embodiment.
[0064]
(Sixth embodiment)
A sixth embodiment of the invention of this application will be described.
The sixth embodiment of the invention of this application corresponds to the distance measuring device in the first embodiment replaced with the following distance measuring device.
FIG. 5 is a diagram for explaining the principle of a distance measuring device 6 used in the sixth embodiment of the invention of this application. FIG. 5 (a) is a plan view thereof (viewed from above the device). (B) is a side view thereof (viewed from the side of the apparatus), and FIG. 6 (C) is a diagram showing a distance measuring photoelectric converter 6S used in the distance measuring apparatus 6 and its connection relationship.
[0065]
5A to 5C, 2 is a light source for reading optical information, 41 is a vibrating mirror, 6L is a light receiving lens for distance measurement, 6S is a photoelectric converter for distance measurement, and 6A is a differential amplifier.
The reference symbol u attached to the ranging photoelectric converter 6S indicates the upward direction of the ranging photoelectric converter 6S.
Code 1_T, 2_T, And 3_TIndicates a representative position of an object to be read T (not shown)._S, 2_S, And 3_SIndicates the positions of scanning lines (trajectory of flying points) made of reflected light corresponding to these positions.
2 to be read T_TTo 3_TWhen moving to (that is, approaching), the trajectory of the scanning line composed of reflected light is 2_STo 3_S(I.e., move downward). This can be easily understood by referring to FIG.
On the contrary, the read object T is 2_TTo 1_TWhen moving to (moving away), the trajectory of the scanning line is 2_STo 1_STo move (move upward). This can be understood in the same manner.
[0066]
  The ranging photoelectric converter 6S includes two light receiving areas A and B. The shape of the light receiving areas A and B is a shape formed by dividing a square or a rectangle into two equal parts by one oblique line as shown in FIG. When a square or a rectangle is divided along a diagonal line, the shapes of the regions A and B are right-angled triangles. Otherwise, the shape is a trapezoid.
  The two areas A and B are electrically insulated. Photocurrent output I in both regions_A, I_BIs proportional to the time (distance) the scanning line (flying point) passes through the surface.
  The scanning line (flying point) passes through the area A, where 2c is the vertical length of the photoelectric converter 6S for distance measurement, and d (−c ≦ d ≦ c) is the distance from the center to the locus of the scanning line. Since time is proportional to (c−d) and time passing through region B is proportional to (c + d),
      I_A= P (cd)
      I_B= P (c + d)
It becomes. However, p is a proportionality constant (it depends on the intensity of light).
0067]
oneThe other region A is connected to the + terminal of the differential amplifier 6A, and the other region B is connected to the-terminal of the differential amplifier 6A. The output terminal has a differential voltage signal V_XIs obtained.
        V_X= -2Apd (18)
          However, A is the gain of the differential amplifier 6A.
  The scanning line is the line 2 in FIG._SWhen passing over, the output V of region A_AAnd region B output V_BAre the same, the output V of the differential amplifier 6A_XBecomes zero.
  Scan line is line 3_SWhen passing over (when the object T to be read is near the near point), the output V of the area A_AIs the output V of region B_BThe output V of the differential amplifier 6A._XIs a negative value.
  When the scanning line passes over the line 1s (when the object T to be read is near the far point), the output V of the area A_AIs the output V of region B_BThe output V of the differential amplifier 6A._XIs a positive value.
  At this time, the sign of d becomes negative and d = − | d |.
  If the above equation is rewritten, the following equation is obtained.
        d = -V_X/ 2Ap (18 ')
[0068]
In order to use the theory of triangulation, a base line BL crossing the ranging light receiving lens 6S is considered (see FIG. 5B). The distance from the base line BL (ranging light receiving lens 6L) to the read object T is defined as D._XE, the distance on the base line BL from the scanning center line to the ranging light receiving lens 6L, f, the distance from the base line BL (ranging light receiving lens 6L) to the ranging photoelectric converter 6S, and the ranging light reception The distance from the optical axis of the lens 6L to one end (u side end) of the ranging photoelectric converter 6S is b.
When the amount of received light is controlled to a substantially constant value, the distance D to the reading object T_XIs given by:
D_X= Ef / (b + c-V_X/ 2Ap) (19)
[0069]
The derivation process of the above equation (19) is as follows.
According to FIG. 5 (b), the height is D._XAnd a right triangle whose base is e and a right triangle whose height is f and whose base is (b + c + d) can be considered. Both are clearly similar because their hypotenuses are on the same line segment 3 '. According to the similar theory,
D_X/ E = f / (b + c + d)
∴D_X= Ef / (b + c + d) (20)
Substituting equation (18 ′) into equation (20) yields equation (19).
When the connection polarity from the distance measuring photoelectric converter 6S to the differential amplifier 6A is reversed, the following equation is used instead of the equation (19).
D_X= Ef / (b + c + V_X/ 2Ap) (19 ')
[0070]
If the luminance of the light source is constant without being controlled, the amount of received light is inversely proportional to the square of the distance. The photocurrent I in this case_A, I_BIs as follows.
I_A= P (cd) (D_O/ D_X)²
I_B= P (c + d) (D_O/ D_X)²
Ｖ V_A= Ap (cd) (D_O/ D_X)²
V_B= Ap (c + d) (D_O/ D_X)²
Where A is the gain of the amplifier.
V_AAnd V_BWhen calculating the sum and difference of
V_A-V_B= -2Apd (D_O/ D_X)²
V_A+ V_B= 2Apc (D_O/ D_X)²
Divide side by side, Ap and (D_O/ D_X)
(V_A-V_B) / (V_A+ V_B) = V_X/ (V_A+ V_B) = − D / c
Ｄ d = -cV_X/ (V_A+ V_B(21)
Substituting the above equation into equation (20) yields the following equation:
D_X= Ef / {b + c-cV_X/ (V_A+ V_B)} (22)
(By the way, when the amount of received light is controlled to a substantially constant value,
V_A+ V_B= 2Apc, and Equation (22) matches Equation (19). )
[0071]
(Seventh embodiment)
A seventh embodiment of the invention of this application will be described.
The seventh embodiment of the invention of this application corresponds to the distance measuring device in the first embodiment replaced with the following distance measuring device.
FIG. 16 is a block diagram of the input circuit of the distance measuring apparatus used in the seventh embodiment.
In FIG. 16, reference numeral 2 denotes a light source for scanning barcode scanning, 2D denotes a light source driving circuit, 6
S is a photoelectric sensor for distance measurement, and 9 is a centralized control device (for example, a microprocessor unit).
Also in the seventh embodiment, a bar code reading / scanning light source (for example, laser) 2 is used as a projection light source for distance measurement.
[0072]
  In principle, the ranging photoelectric converter 6S used in the seventh embodiment is the focusing lens position detecting photoelectric converter 32PS used in the first embodiment (FIGS. 2, 3 and 15). As shown in the figure, an elongated light receiving surface and a first photocurrent output terminal t₁And a second photocurrent output terminal t₂And a common electrode.
  The first and second photocurrent outputs differ depending on the incident position of the light spot on the light receiving surface.
  Assuming that the length of the light receiving surface is 2c and the distance from the center position of the light receiving surface to the incident position of the light spot is d, the ratio of both currents is as follows.
      I₂/ I₁= (C + d) / (cd)
                  = (1 + d / c) / (1-d / c) (23)
  The derivation process of Equation (23) is as follows.
  First output terminal t₁First photocurrent I from₁From the incident position of the light spot to the second output terminal t₂Is proportional to the distance to. This distance is (c-D),
      I₁= P (c-D) (24)
          However, p is a proportionality constant (however, it depends on the amount of received light).
  Similarly, the second photocurrent I₂Is the first output terminal t from the incident position of the light spot.₁Is proportional to the distance to. This distance is (c+ D),
      I₂= P (c+ D) (25)
  By dividing equation (25) by equation (24) and eliminating the proportionality constant p, equation (23) is obtained.
[0073]
Also in the seventh embodiment, the oscillating mirror type scanning device 4, the read object T, and the distance measuring light receiving lens 6L are used, which are the same as those in the first embodiment.
As described above, the distance measuring photoelectric converter 6S of the seventh embodiment is different from that of the first and sixth embodiments, but the arrangement relationship thereof is the same as that of the sixth embodiment (FIG. 5B). ))). That is, the distance measuring light-receiving lens 6L and the distance measuring photoelectric converter 6S of the seventh embodiment are disposed on the base line D. (The illustration is omitted.)
At the time of distance measurement according to the seventh embodiment, the oscillating mirror 41 is stopped, and light is projected in a direction perpendicular to the base line D (the direction of the scanning center, θ = 0 °).
In the meantime, in order to increase the light receiving sensitivity of the distance measuring device 6, various control devices are operated so that the projection beam is parallel light, the aperture is open, and the light emission output is maximized as much as possible. (However, the light emission output must be stopped within the range limited by the safety standard of light emission, etc.)
The reflected light L from the object to be read T is collected by the ranging light receiving lens 6L and imaged on the light receiving surface of the ranging photoelectric converter 6S. The first output terminal t₁To the first photocurrent I₁To the second output terminal t₂To the second photocurrent I₂Is generated.
[0074]
First and second photocurrents I₁, I₂Respectively, by means of a current-voltage converter I-V.₁, V₂Is converted to Voltage signal V₁, V₂Are amplified by the variable amplifier AMP and input to the sample hold circuit S / H.
The light projecting light source 2 is driven by a light source driving circuit 2D. The amount of light is controlled by a light output control signal LPCS from a centralized control device (for example, a microprocessor unit) 9. Lighting (extinguishing) of the light projecting light source 2 is controlled by a lighting (extinguishing) command signal LOS.
During the distance measuring operation, the light source 2 is pulse-driven to eliminate the influence of ambient light. The actual lighting time is about 10 to 1000 microseconds per measurement. This time is determined to be an optimum value depending on the pulse response speed characteristics of the light projecting light source 2 and the light receiving circuit.
[0075]
The first and second output terminals are connected to the current I by the ambient light even when the light projecting light source 2 is turned off._{1 of}, I_{2 of}Will occur.
Current component I derived from ambient light_{1 of}, I_{2 of}In order to eliminate the influence of_{1 of}, V_{2 of}Are respectively AD-converted by the AD converter A / D and input to the centralized control device (for example, a microprocessor unit) 9 as digital data.
Immediately thereafter, the centralized control device (for example, the microprocessor unit) 9 emits a lighting command signal LOS to light the projection light source 2.
The first and second sample and hold circuits S / H and S / H are respectively synchronized with the lighting command signal LOS, and the voltage signal V during lighting_{1 ON}, V_2ONIs sampled and held. Their voltage signal V_{1 ON}, V_2ONAre respectively A / D converted by the AD converter A / D and input to the centralized control device (for example, a microprocessor unit) 9 as digital data.
[0076]
Since each voltage data is stored as a logical value in the centralized control device (for example, the microprocessor unit) 9, the following calculation can be easily executed.
Voltage data at lighting V_{1 ON}, V_2ONTo voltage data V_{1 of}, V_{2 of}Is subtracted and the true distance measurement data V_1t, V_2tCalculate That is,
V_1t= V_{1 ON}-V_{1 of}
V_2t= V_2ON-V_{2 of}
From both formulas, V_2t/ V_1tIs calculated. That is,
V_2t/ V_1t= (V_2ON-V_{2 of}) / (V_2ON-V_{2 of}(26)
V_2t/ V_1tIs I in the above formula (23).₂/ I₁It corresponds to.
Therefore, the above equation (26) is replaced with I in the above equation (23).₂/ I₁Into the distance measurement value D_XCan be calculated.

[0077]
The above calculation inside the centralized control device (microprocessor unit) 9 can be normally performed in 100 μsec or less.
In order to improve the measurement accuracy, the above measurement sequence is repeated and an average value is output. The number of repetitions is usually 10 to 20 times. Therefore, the measurement time per time is usually 1 msec or less.
In order to improve the measurement accuracy, it is necessary to increase the amount of light to be projected. However, as described above, there is a limitation.
[0078]
In order to increase the quantization accuracy of the A / D converter, the lighting data V_{1 ON}And V_2ONIf both are small values, the centralized control device (microprocessor unit) 9 increases the amplification factor by the amplification factor switching signal ACS to obtain an optimum input value, and then repeats the measurement sequence.
Conversely, lighting data V_{1 ON}Or V_2ONWhen the value exceeds the maximum input value of the A / D converter, the centralized control device (microprocessor unit) 9 reduces the amplification factor by the amplification factor switching signal ACS and then repeats the measurement sequence.
These are distance measurement distance D_XThis is because the intensity of the reflected light that can be received changes.
[0079]
(Eighth embodiment)
An eighth embodiment of the invention of this application will be described.
The eighth embodiment of the invention of this application corresponds to a case where the focusing lens position detection means 32 in the focusing device 3 of the first embodiment is replaced with the following focusing lens position detection means.
The intensity of light (ie, side light) in a direction away from the optical axis of the light source (eg, laser) 2 by an angle φ is a decreasing function of the angle φ.
Therefore, if the light receiving surface of the focusing lens position detection position lens 32PL moves forward (if the x coordinate of the focusing lens 31 increases), the amount of received light increases, and if it moves backward (focusing lens 31). The amount of received light decreases. That is, if the focusing lens 31 moves forward, the output of the focusing lens position detecting photoelectric conversion element 32PS increases, and if the focusing lens 31 moves backward, the output of the photoelectric conversion element 32PS decreases. .
That is, the output (position detection signal) of the focusing lens position detection unit 32 is a monotonically increasing function of the x coordinate of the focusing lens 31.
Therefore, the x coordinate of the focusing lens 31 can be obtained by obtaining the inverse function of the monotonically increasing function.
[0080]
(Other examples)
Other embodiments will be described.
Other embodiments are generated by combining the items in the above-described embodiments and the following items.
(A) The focusing lens position detecting photoelectric converter 32PS in the focusing lens position detecting means 32 of the focusing device 3 of the first embodiment is composed of a large number of photoelectric conversion elements and position detecting arithmetic circuits. I can do it.
(B) The driving means in the vibrating mirror type scanning device 4 of the first embodiment can be constituted by a piezoelectric electromechanical transducer.
(C) The focusing lens moving means 33 in the focusing device 3 of the first embodiment can be configured as a movable iron piece.
(D) The centralized control device 9 can be constituted by an ASIC.
(E) The electronic circuit portion in each embodiment can be integrated with the centralized control device 9 to form a system-on-chip.
[0081]
【The invention's effect】
Since the invention of this application is configured as described above, it is possible to achieve remarkable effects as described in the following (a) to (1).
(A) An optical information reader with an extremely long reading depth that can accurately read optical information even when the object to be read is at a far point or near point and the reading distance is not constant. Can be realized. In other words, an optical information reading apparatus having a very large reading range can be realized.
(B) A compact, lightweight and low-cost focusing device and distance measuring device can be realized. As a result, a compact, lightweight, and low-cost optical information reading apparatus can be realized as a whole.
(C) A hand-held optical information reader equipped with a compact, lightweight, and low-cost focusing device and distance measuring device can be realized.
[0082]
(D) By adding a variable aperture device to the focusing device, when the object T to be read is at a near point, an excessive increase in resolution due to an excessively thin beam waist is prevented. Is at a far point, the resolution is not lowered too much due to the beam waist becoming too thick, so that the resolution is maintained within an appropriate range over a very long depth, and the read object T is brought to the near point. At some point, optical information reading that prevents a sudden increase in the beam diameter before and after the near point, thereby preventing a change in resolution associated with the deflection of the scanning beam and greatly improving the S / N ratio. A device can be realized.
(E) Optical intensity in which the received light amount of the photoelectric converter 7 is maintained within an appropriate range by controlling the luminance (and hence the light amount) of the light source based on the linear function of the distance measurement signal and / or the scanning angle signal. An information reading apparatus can be realized.
(F) By using a vibrating mirror type scanning device having a scanning mirror on the front surface and a light receiving mirror on the rear surface, that is, by using the light receiving mirror on the rear surface exclusively for light reception, the light receiving aperture is increased, and thus the amount of received light is increased. Thus, an optical information reading apparatus can be realized.
[0083]
(G) By using the distance measurement data and adjusting the scanning angle, a necessary reading width can be ensured at both near and far points.
(H) By using the distance measurement data to control the laser light power, it is possible to stabilize the light receiving gain and the visibility.
(I) By controlling the light receiving gain using the distance measurement data, it is possible to contribute to stabilization of the light receiving gain.
(J) The frequency band of the electrical analog signal can be controlled by adjusting the scanning speed using the distance measurement data.
(K) By using the scanning angle data to adjust the laser light power or the light receiving gain, it is possible to compensate for the decrease in the amount of received light on both sides of the scanning.
(1) Using the scanning angle data, it is possible to correct the shift of the in-focus object due to the optical path difference between the scanning center and both sides.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of a first embodiment of an optical information reading apparatus according to the invention of this application;
FIG. 2 is an operation principle diagram of the automatic focusing device used in the first embodiment.
FIG. 3 is a longitudinal sectional view of an optical focusing unit forming a main part of the automatic focusing device.
FIG. 4 is a diagram illustrating the principle of a first distance measuring device used in the first embodiment.
FIG. 5 is a diagram illustrating the principle of a second distance measuring device used in the first embodiment.
6 is a horizontal sectional view and a vertical sectional view of the vibrating mirror type scanning device used in the first embodiment. FIG.
FIG. 7 is an operation principle diagram of a variable aperture device used in the second embodiment of the optical information reading device according to the invention of this application.
FIG. 8 is an operation principle diagram of a focusing device and a variable aperture device used in a third embodiment of the optical information reading device according to the invention of this application.
FIG. 9 is a longitudinal sectional view of a laser beam after passing through a focusing lens.
FIG. 10 is a graph showing a waist position and a diameter of a laser beam after passing through a fixed aperture.
FIG. 11 is a graph showing a waist position and a diameter of a laser beam after passing through a variable aperture.
FIG. 12 is a diagram showing an overall configuration of a fourth embodiment of the optical information reading device according to the present invention;
FIG. 13 is a diagram showing a scanning vibration mirror type scanning device used in the fourth embodiment.
FIG. 14 is a diagram illustrating a light collection position by a focusing lens.
FIG. 15 is a block diagram of a focusing lens position control circuit.
FIG. 16 is a block diagram of an input circuit of a distance measuring device used in a seventh embodiment of the invention of this application.
FIG. 17 is a block diagram of a light source driving circuit.
FIG. 18 is an operation principle diagram of a conventional autofocus scanner.
FIG. 19 is a perspective view of a physical distribution sorting system using a conventional autofocus scanner.
[Explanation of symbols]
1 housing
2 Light source
2D light source drive device
3 Automatic focusing device (automatic convergence system)
31 Focusing lens
32 Focus lens position detection means
32PL Focusing lens Position detection lens
32PS photoelectric lens for focusing lens position detection (element)
32PC focusing lens position calculation circuit
33 Focusing lens moving means
33C Movable wire ring (excitation wire ring)
33CD focusing lens position drive circuit
33M permanent magnet
33Y yoke
34 Focusing lens position servo circuit
35 Electronic voltage divider
3B barrel (barrel)
3H focusing lens holder
3LL Focusing lens position detection laser light
3SP support spring
3U optical focusing unit
4 Vibration mirror type scanning device
41₁  First oscillating mirror (scanning mirror)
41₂  Second vibrating mirror (light receiving mirror)
42 Moving parts
421 Movable magnet
422 Movable yoke (yoke)
424 Magnetic material
425 Rotating shaft
46 Holder
47 Fixed yoke
47₁Opposite side of fixed yoke
47₂Opposite side of fixed yoke
48 Fixed magnet
49 Driveline wheel
5 Light receiving optical system
6 Ranging device (distance meter)
6A differential amplifier
6C Ranging calculation means
6L ranging lens
6P Distance projector
6R Photoelectric converter for distance measurement
6s Photoelectric conversion element for distance measurement
6S Photoelectric converter for ranging
7 Photoelectric converter (photoelectric converter)
8 Signal processor
9 Centralized control device (eg microprocessor unit)
10 Variable throttle device
DS distance signal
I Variable aperture
IC variable aperture control circuit
LB laser beam
M Electric motor
MC focusing lens position and aperture rotation angle control circuit
Monitoring signal of MS laser diode
p Optical information pattern (eg barcode symbol)
SB scanning beam
T Object to be read (for example, label)
TS temperature sensor
VD electronic voltage divider

Claims (7)

A light source (2) for emitting a light beam for scanning the object (T) to be read;
A focusing device (3) for focusing the light beam emitted from the light source (2) on the read object (T);
A vibrating mirror type scanning device (4) for periodically reflecting and deflecting the light beam in a horizontal plane;
A light receiving optical system (5) for collecting the reflected light reflected from the read object (T) at a predetermined position;
A photoelectric converter (7) disposed at the predetermined position and converting the reflected light into an electrical analog signal;
A signal processing unit (8) connected to an output terminal of the photoelectric converter (7);
A distance measuring device (6) for measuring a distance from the vibrating mirror type scanning device (4) to the object to be read (T);
Containing
The focusing device (3)
A focusing lens (31) for focusing the light beam emitted from the light source (2) on the object to be read (T);
A focusing lens support means (39) for supporting the focusing lens (31) so as to be displaceable only in the optical axis direction;
Focusing lens moving means (33) capable of moving the focusing lens (31) in the optical axis direction;
Focusing lens position detection means (32);
A focusing lens position servo circuit (34) and
The focusing lens position detecting means (32)
A focus lens position detection position lens (32PL);
A focusing lens position detecting photoelectric converter (32PS);
Focusing lens position calculation circuit (32PC)
Containing
The distance measuring device (6) and the focusing device (3) are connected so as to give a distance signal from the distance measuring device (6) as a position command signal to the focusing device (3). ,
The focusing lens position servo circuit (34) is configured to receive the position command signal, convert it into a position control signal, and give it to the focusing lens moving means (33).
Optical information reading device. The focusing lens moving means (33) contains the electromagnetic drive mechanism, the electromagnetic drive mechanism, an excitation line wheels 33C, composed of the permanent magnet 33M, the yoke (yoke) 33Y, claim 1, wherein Optical information reader. The focusing device (3) further includes focusing lens position detection means (32), and the focusing lens position detection means (32) determines the position of the focusing lens (31) in the optical axis direction. Configured to detect and output a position detection signal,
The focusing lens position servo circuit (34) receives the position command signal and the position detection signal, forms a difference signal between the two signals, and uses the difference signal as a position control signal to move the focusing lens moving means. The optical information reading device according to claim 1 , wherein the optical information reading device is configured to be given to (33). Furthermore, it contains a variable aperture means (10), the variable aperture means (10) contains a variable aperture (I) and an aperture control circuit (IC),
The variable aperture (I) is disposed in front or rear of the focusing device (3),
The aperture control circuit (IC) and the distance measuring device (6) are configured to give a distance signal from the distance measuring device (6) as an aperture command signal to the aperture control circuit (IC). Connected,
The optical information reader according to claim 1 . The focusing lens moving means (33) includes a feed screw mechanism (FM), a feed screw mechanism driving means (FD), and a focusing lens position control circuit (MC).
The optical information reader according to claim 1 . A focusing lens (31) for focusing the light beam emitted from the light source (2) on the read object (T);
A focusing lens support means (39) for supporting the focusing lens (31) so as to be displaceable only in the optical axis direction;
Focusing lens moving means (33) capable of moving the focusing lens (31) in the optical axis direction;
A focusing lens position servo circuit (34) and
The focusing lens position servo circuit (34) is configured to receive the position command signal, convert it into a position control signal, and give it to the focusing lens moving means (33).
The optical information reader according to claim 1 . The focusing device (3) further includes focusing lens position detection means (32), and the focusing lens position detection means (32) determines the position of the focusing lens (31) in the optical axis direction. Configured to detect and output a position detection signal,
The focusing lens position servo circuit (34) receives the position command signal and the position detection signal, forms a difference signal between the two signals, and uses the difference signal as a position control signal to move the focusing lens moving means. The optical information reading device according to claim 6 , wherein the optical information reading device is configured to be provided to (33).

Images