JP2004287744A - Image scanner, image position correction method for image scanner, program for executing the method, and computer-readable record medium storing the program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the correction of image fluctuation, the shortening of an adjusting time in a production stage, and the correction of deterioration of a read image with time in use. <P>SOLUTION: This image scanner has a plurality of displacement measuring means for measuring the scanning displacement of at least one reflecting member in at least two points. Accordingly, the image fluctuation can be corrected, and slippage of a reading position by inclination or vibration of an optical member can be corrected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００２６】
次に、出射光束と反射の様子を示す図７のように、原点平面６１上のある点Ｐ（ｘｓ，ｙｓ、ｚｓ）から出射した出射光束ベクトルが反射面のどこに当たるかを考える。出射光束ベクトルは単位ベクトルＱ方向に進行し点Ｋ（ｘｐ，ｙｐ，ｚｐ）で反射し、反射光束ベクトルＱ’方向に反射すると考える。ＰＫ＝ｌとすると、以下の連立方程式が成り立つ。
【００２７】
ｘｐ＝ｘｓ＋ｌＱｘ （３）
ｙｐ＝ｙｓ＋ｌＱｙ （４）
ｚｐ＝ｚｓ＋ｌＱｚ （５）
Ｅｘｐ＋Ｆｙｐ＋Ｇｚｐ＋Ｈ＝０ （６）
【００２８】
ここで、（６）式は反射面の方程式であり、Ｅ，Ｆ，Ｇ，Ｈは定数である。
（６）式に式（３），式（４），式（５）を代入し、整理すると以下の式が得られる。
【００２９】
ｌ＝−（ｘｓＥ＋ｙｓＦ＋ｚｓＧ＋Ｈ）／（ＱｘＥ＋ＱｙＦ＋ＱｚＧ）
（７）
【００３０】
求められたｌを（３）〜（５）式に代入することで点Ｋの座標を求めることができる。
【００３１】
一方、反射法線単位ベクトルＥ’は出射面の法線ベクトルＥを用いて以下のように表すことができる。
【００３２】
Ｅ’＝Ｃ・Ｅ （８）
【００３３】
出射光束ベクトルの単位ベクトル［Ｑｘ，Ｑｙ，Ｑｚ］を用いると、反射方向を示す反射光束ベクトル［Ｑ’ｘ，Ｑ’ｙ，Ｑ’ｚ］は反射行列を用いて、以下のように表すことができる。
【００３４】
【数２】

【００３５】
次に、出射光束と反射の様子を示す図８に示されるように、反射面６３上の点Ｋから出射した出射光束単位ベクトルＱ’が反射面６４のＭ点に当たって反射光束ベクトルＱ’’の方向に反射する。これは上記（１）式〜（９）式の計算を行うことで反射光束ベクトルＱ’’の位置及び方向を求めることができる。
【００３６】
以上のような一連の計算を順次各反射面に対して行っていく。その一連の計算の一例を図９に示す。同図において、原稿面平面６１上の点Ｐから出射した光束は反射面６３上の点Ｋに当たり、反射されて、反射面６４上の点Ｍに当たって、Ｑ’’の方向に反射する。更に、反射面６５上の点Ｎに当たってＱ’’’方向に反射する。結像レンズ６６による屈折作用は光線追跡手法によって計算されることが多い。
【００３７】
しかし、光線追跡ソフトウェアは汎用のものが多く、他の計測システムと組み合わせて使用することは困難であった。また、従来のソフトウェアは屈折界面での屈折の組み合わせで記述されており、レンズという部品単位での計算はできなかった。
【００３８】
そこで、結像レンズ毎での屈折を幾何学的な一般式にすることで結像レンズを通過する光束の光線追跡を行って、結像位置を求める。結像レンズの傾き・並進は結像レンズ自身の組付け精度と画像読取装置への組付け精度によって決まる。結像レンズ自身の持つ反射偏心あるいは透過偏心は、レンズ偏心測定機等で測定可能で、画像読取装置への組付けは組付け治具の精度で決まる。実際には結像レンズ自身の傾き・並進公差と画像読取装置への組付け公差の積上げ公差を考慮して計算を行い、最終的な読取位置の誤差を見積もった方がよい。
【００３９】
次に、図１０の（ａ）〜（ｆ）を用いてレンズの屈折による結像位置算出手順について説明する。
図１０の（ａ）に示すように、反射面７１の点Ｖ（Ｖｘ，Ｖｙ，Ｖｚ）から反射した出射光単位ベクトルＳ（＝Ｑ’’’）はレンズ面７２上の交点Ｋ（Ｘｋ，Ｙｋ，Ｚｋ）上で屈折する。このときのＫの座標と屈折方向を求める。レンズ面７２は元座標系に対して回転もしくは並進された状態を考える。これはレンズの取り付け誤差を考慮するためである。この場合は図１０の（ｂ）のように座標系をレンズ面７２の回転もしくは並進に合わせた座標変換を行う。元座標系のままでレンズ面の回転もしくは並進を考える方法もあるが、レンズ面が非球面である場合を考えると変換座標系に変換して計算を実行する方が計算式は簡単になる。元座標系をＸＹＺとし、それぞれの軸回りの回転をγ，α，β、並進をＵｘ，Ｕｙ，Ｕｚとする。なお、図１０の（ａ），（ｂ）では回転角がβ、並進量がＵｙの状態を示している。並進及び回転成分を加えると、座標変換後の点Ｖ’（Ｖ’ｘ，Ｖ’ｙ，Ｖ’ｚ）及び出射光ベクトルＳ’（Ｓ’ｘ，Ｓ’ｙ，Ｓ’ｚ）は以下のように表現される。
【００４０】
［Ｖ’ｘ Ｖ’ｙ Ｖ’ｚ］＝［Ｖｘ−Ｕｘ Ｖｙ−Ｕｙ Ｖｚ−Ｕｚ］［Ｒ］ （１０）
［Ｓ’ｘ Ｓ’ｙ Ｓ’ｚ］＝［Ｓｘ Ｓｙ Ｓｚ］［Ｒ］ （１１）
【００４１】
ここで［Ｒ］は回転行列であり、以下のように表現される。
【００４２】
【数３】

【００４３】
出射光ベクトルＳ’は並進の影響は受けないので回転行列のみを作用させる。
【００４４】
次に、変換座標系での出射光とレンズ面７２との交点Ｋ’（Ｘ’ｋ，Ｙ’ｋ，Ｚ’ｋ）を求める。
【００４５】
【数４】

【００４６】
とすると以下の連立方程式が成り立つ。
【００４７】
Ｘ’ｋ＝Ｖ’ｘ＋ｍＳ’ｘ （１３）
Ｙ’ｋ＝Ｖ’ｙ＋ｍＳ’ｙ （１４）
Ｚ’ｋ＝Ｖ’ｚ＋ｍＳ’ｚ （１５）
【００４８】
【数５】

【００４９】
ここで、（１６）式は非球面曲面の方程式である。ＣｎはＣｏｎｉｃ定数であり、Ｃｎの値により曲面の形が変化する。（Ｃｎ＞０：楕円、Ｃｎ＝０：放物面、Ｃｎ＜０：双曲面、Ｃｎ＝１：球面）ｒはレンズ面１の曲率半径である。
【００５０】
上記（１３）式〜（１６）式を解いてｍを求め、（１３）式〜（１５）式に代入することで交点Ｋ’の座標を求めることができる。
【００５１】
次に、レンズ面での屈折方向を計算する。図１０の（ｃ）に示されるように、出射光ベクトルＶ’は屈折率Ｎの媒質中を伝播し、屈折率Ｎ’のレンズ面７２で屈折して屈折光ベクトルＴ’（Ｔ’ｘ，Ｔ’ｙ，Ｔ’ｚ）の方向に屈折する。
【００５２】
そして、図１０−（ｄ）のように、交点Ｋ’におけるレンズ面７２上の法線ベクトルＥ’（Ｅ’ｘ，Ｅ’ｙ，Ｅ’ｚ）を考える。このときレンズ面７２への入射角をｉ、屈折光ベクトルと法線ベクトルの成す角をｉ’とする。（１６）式をＸ’ｋについて変形すると下記の（１７）式を得る。
【００５３】
【数６】

【００５４】
法線ベクトルの各成分は勾配を取ることで計算できる。
【００５５】
【数７】

【００５６】
とすると以下のようになる。
【００５７】
Ｅ’ｘ＝１ （１９）
Ｅ’ｙ＝−Ｙ’ｋ／Ｂｒ （２０）
Ｅ’ｚ＝−Ｚ’ｋ／Ｂｒ （２１）
Ｅ’・Ｓ’＝ｃｏｓ ｉ及びＥ’・Ｔ’＝ｃｏｓ ｉ’ なる関係を用いてスネルの法則
【００５８】
｜Ｎ｜（Ｅ’×Ｓ’）＝｜Ｎ’｜（Ｅ’×Ｔ’） （２２）
【００５９】
を変形すると、屈折光ベクトルＴ’（Ｔ’ｘ，Ｔ’ｙ，Ｔ’ｚ）は以下のように求まる。
【００６０】
Ｔ’＝ＮＳ’／Ｎ’＋Ｅ’（ｃｏｓ ｉ’− Ｎｃｏｓ ｉ／Ｎ’） （２３）
ここで ｃｏｓ ｉ’は以下のように計算できる。
【００６１】
【数８】

【００６２】
ｓｉｇｎ（ｃｏｓ ｉ）はｃｏｓ ｉの正負によって＋１もしくは−１の値を取る関数である。
【００６３】
以上（１０）式〜（２４）式を用いてレンズ面７２での交点Ｋ’及び屈折光ベクトルＴ’が求まる。これら一連の計算を次の面に対しても同様に行う。
【００６４】
図１０−（ｅ）に示されるようにレンズ面７２の後面にレンズ面７３を考え、レンズが存在する場合は前記で求まった交点Ｋ’を出射点座標、屈折光ベクトルＴ’を出射光ベクトルと考えて同様の計算を行うことでレンズの屈折計算を行う。
このようにして最終的にレンズから出射する交点Ｋ’１（Ｘ’ｋ１，Ｙ’ｋ１，Ｚ’ｋ１）及び屈折光ベクトルＴ’１（Ｔ’ｘ１，Ｔ’ｙ１，Ｔ’ｚ１）が求まる。
【００６５】
次に、図１０−（ｆ）に示されるように、座標系Ｘ’Ｙ’Ｚ’を元座標系ＸＹＺに戻す。回転行列を［Ｒ］とすればレンズの傾きのみを元の座標系に戻すと以下のようになる。
【００６６】
［Ｘｓ Ｙｓ Ｚｓ］＝［Ｒ］^−１［Ｘ’ｋ１ Ｙ’ｋ１ Ｚ’ｋ１］ （２５）
【００６７】
このとき［Ｒ］^−１は以下のように与えられる。
【００６８】
【数９】

【００６９】
並進成分を元に戻せば、交点Ｋ１は以下のようになる。
【００７０】
［Ｘｋ１ Ｙｋ１ Ｚｋ１］＝［Ｘｓ＋Ｕｘ Ｙｓ＋Ｕｙ Ｚｓ＋Ｕｚ］ （２７）
【００７１】
また、屈折光ベクトルＴ１は以下のように元の座標系に戻すことができる。
【００７２】
［Ｔｘ１ Ｔｙ１ Ｔｚ１］＝［Ｒ］^−１［Ｔ’ｘ１ Ｔ’ｙ１ Ｔ’ｚ１］ （２８）
【００７３】
屈折光ベクトルＴ１は並進の影響を受けないので回転行列のみを作用させる。
【００７４】
このようにして、レンズでの屈折を計算することができる。レンズが複数ある場合も（１０）式〜（２８）式の計算を繰り返し実行することで計算することができる。
【００７５】
次に、結像位置の座標を求める。結像面７４での結像位置Ｐｉ［Ｘｉ，Ｙｉ，Ｚｉ］は
【００７６】
【数１０】

【００７７】
とすると以下の連立方程式が成り立つ。
【００７８】
Ｘｉ＝Ｘｋ１＋ｎＴｘ１ （２９）
Ｙｉ＝Ｙｋ１＋ｎＴｙ１ （３０）
Ｚｉ＝Ｚｋ１＋ｎＴｚ１ （３１）
Ｅ_２Ｘｉ＋Ｆ_２Ｙｉ＋Ｇ_２Ｚｉ＋Ｈ_２＝０ （３２）
ただし、Ｅ_２、Ｆ_２、Ｇ_２、Ｈ_２は定数である。
【００７９】
（３２）式に（２９）式，（３０）式，（３１）式を代入し整理してｎを求める。
求まったｎを（２９）式〜（３１）式に代入することで結像位置Ｐｉ［Ｘｉ，Ｙｉ，Ｚｉ］の座標を求めることができる。このようにして最終的に結像面での座標が計算できる。結像面での座標を元にレンズの結像倍率から画像読取位置が計算される。レンズの結像倍率をＶとすれば、画像読取位置［Ｘｇ，Ｙｇ，Ｚｇ］はそれぞれ以下のように計算できる。
【００８０】
Ｘｇ＝Ｘｉ／Ｖ （３３）
Ｙｇ＝Ｙｉ／Ｖ （３４）
Ｚｇ＝Ｚｉ／Ｖ （３５）
【００８１】
また、光線の伝播は可逆性が成り立つので、結像面側から光線追跡を行って、画像読取位置を計算することもできる。主光線のみを考えればこの方法は直接、画像読取位置を求めることができる。
【００８２】
次に、図３のように反射ミラー３２の両端に反射治具３４を取り付け、非接触変位計３５の測定光３６をその反射治具３５に当て、非接触変位計３５に再び光が戻るようにセットする。これによって副走査方向の変位を測定し、反射ミラー３２の副走査方向の傾きを計算する。反射ミラー３３も同様の傾きを持つと考える。反射ミラー３１は反射ミラー３２の２倍の変位を持つと考えられるが、正確には反射ミラー３１の変位を測定することが望ましい。一方、反射ミラー３２の両端に非接触変位計３７を取り付け、副走査方向に対して垂直方向に測定光３６をスライドレール３８上に当て非接触変位計３７に再び光が戻るようにセットする。これによって副走査方向に対し垂直方向の変位を測定し、その傾きを計算する。反射ミラー３３も同様の傾きを持つと考える。反射ミラー３１は反射ミラー３２の２倍の変位を持つと考えられるが、正確には反射ミラー３１の変位を測定することが望ましい。
【００８３】
以上の一連の測定及び計算をＡ３原稿全面分の走査範囲にわたって実行し、主走査及び副走査方向に関して読取り位置の変化をプロットしたものを図１１に示す。左表は副走査位置での図３の反射ミラー３１の傾き量を示している。反射ミラーの傾きが走査とともに変動するため、読取位置が変化し、画像ゆらぎが発生することを示している。この図の画像ゆらぎ量は主走査及び副走査方向に対して拡大表示をしている。原稿全面に渡って画像ゆらぎを補正すると長方形状の結果が得られる。
【００８４】
図１２は本実施例の画像位置補正装置を適用した読取位置評価装置の構成を示す透視斜視図である。同図において、図３と同じ参照符号は同じ構成要素を示す。ここで、反射ミラー３２の挙動を計測するためには反射ミラー３２に反射治具３４を取り付けるのが良いが、実際には走行体１３が存在するために反射ミラー３２に直接、反射治具を取り付けるのは難しい。そこで走行体１２もしくは走行体１３に反射治具３４を取り付ける。同図に示す例では走行体１３に反射治具３４を取り付けている。非接触変位計３５の測定光をその反射治具３４に当て、非接触変位計３５に再び光が戻るようにセットする。これによって副走査方向の変位を測定できる。非接触変位計３５は画像読取装置の筺体に固定されている。反射ミラー３２，３３は走行体１３に取り付けられており、走行体１３は剛体と考えてよいので反射ミラー３２，３３は走行体１３と同じ動きをすると考えることができる。すなわち反射ミラー３２，３３は同位相で走行体１３と同じ動きをすると考えてよい。
【００８５】
一方、走行体１２もしくは走行体１３の両端に非接触変位計３７を取り付け、副走査方向に対して垂直方向に測定光３６をスライドレール３８上に当て非接触変位計３７に再び光が戻るようにセットする。この例では走行体１３に非接触変位計を取り付けている。これによって副走査方向に対し垂直方向の変位を測定できる。この場合も同様に走行体と反射ミラーは同じ動きをすると考えられるので、この変位は反射ミラーの変位に相当すると考えてよい。反射治具３４及び非接触変位計３７はそれ自体の質量が走行体のたわみや挙動に影響を及ぼすため、できるだけ小さくしたほうがよく、微小な走行体の傾きを測定するため、２つの反射治具あるいは非接触変位計３７間はなるべく離したほうがよい。更に、副走査方向の走行体の部分的な傾きを得るためには３つ以上の反射治具を取り付け、治具間の部分的な傾きを計算することで、より精密な走行体の傾き測定が可能となる。
【００８６】
また、走行体単体での固有モードを測定あるいは計算し、反射ミラー３２，３３の取り付け部分の挙動及び位相から反射ミラー３２，３３の動きを推定することもできる。この場合は最も振幅の大きい１次モードなどを用いれば反射ミラー３２，３３の相対的な挙動をつかむことが可能になる。固有モードの挙動は有限要素解析やモーダル解析の手法を用いて捉えることができる。
【００８７】
非接触変位計としてはレーザ測長機や静電容量式、うず電流式などの変位計を用いることができる。レーザ式の場合は反射治具及びスライドレールの反射率を高くしておく必要がある。また静電容量式あるいはうず電流式の変位計を用いる場合には反射治具及びスライドレールを導電性のある金属面にする必要がある。また、変位計の代わりに小型レーザドップラー振動計を用いることもできる。この場合には測定された速度変動データを積分し変位に直してから計算する。また、加速度ピックアップで加速度を測定してもよい。この場合は反射ミラーに加速度ピックアップを直接固定する。加速度を測定する場合は２階積分して変位に直す必要がある。
【００８８】
次に、本実施例の画像位置補正装置の別の画像位置補正動作について説明すると、別の画像位置補正方法は反射ミラーまでの光線追跡部分までは上述した動作と同様である。その以降の結像レンズによる屈折作用の計算部分が異なる。結像レンズによる屈折作用は光線追跡手法によってレンズ毎の屈折計算を行う方法が多いが、レンズ枚数が多い場合には計算時間がかかるという問題がある。また、レンズ自身は筺体に固定されているため、位置決めが正確にされていれば傾きや並進は微小で経時的な変化もない。そのような状態で主光線のみで考えれば、以下のような方法でレンズによる屈折作用を計算することができる。
【００８９】
図１３は別の画像位置補正の様子を示す図である。ここでは説明の便宜上、光路を直線上に配置した形で説明する。図１３の（ａ）に示すように、反射面８３の点Ｎから反射した反射光単位ベクトルＱ’’’は結像面８５上の点Ｐｉに結像する。このＰｉの座標を求める。次に、図１３の（ｂ）に示すように、反射光単位ベクトルＱ’’’と逆方向に逆伝搬単位ベクトル
【００９０】
【数１１】

【００９１】
を考え、反射面８２及び反射面８３を取り去った状態で原稿面８１上の出射点Ｒの座標を光線追跡によって求める。出射点Ｒから結像レンズ８６の中心を通る主光線８７は結像面８５上の点Ｐｉに結像する。すなわち反射光単位ベクトルＱ’’’と主光線８７は同じ点Ｐｉに結像する。これは反射面８１の傾きが微小であれば結像関係が崩れないことを利用している。したがって、図１３の（ｃ）に示されるように出射点Ｒから出射した主光線８７の単位ベクトルを光線追跡し、結像位置Ｐｉを求めることで反射光単位ベクトルＱ’’’の結像位置を求めることができる。
【００９２】
図１４は別の画像位置補正方法を説明する図である。同図において、原稿面８１上の出射点は原稿面平面の方程式と逆伝搬単位ベクトルから計算することができる。原稿面平面の方程式は以下のように得られる。
【００９３】
Ｅ_１Ｘ_Ｒ＋Ｆ_１Ｙ_Ｒ＋Ｇ_１Ｚ_Ｒ＋Ｈ_１＝０ （３６）
ただし、Ｅ_１、Ｆ_１、Ｇ_１、Ｈ_１は定数である。
【００９４】
次に、出射点Ｒの座標を求める。点Ｔ（Ｘｔ，Ｙｔ，Ｚｔ）から
【００９５】
【数１２】

【００９６】
方向に出た光は原稿面上の出射点Ｒ（ＸＲ，ＹＲ，ＺＲ）に当たる。
【００９７】
【数１３】

【００９８】
であり、
【００９９】
【数１４】

【０１００】
とすると以下の式が成り立つ。
【０１０１】
【数１５】

【０１０２】
（４０）式に（３７）式、（３８）式、（３９）式を代入し整理する。
【数１６】

【０１０３】
（４１）式よりｍを求め、（３７）式〜（３９）式に代入することでＲ点の座標が求まる。同様の手順で出射点（ＸＲ，ＹＲ，ＺＲ）から出た主光線２ベクトル（Ｒｘ，Ｒｙ，Ｒｚ）が結像する結像位置（Ｘｉ，Ｙｉ，Ｚｉ）を求めることができる。
【０１０４】
【数１７】

【０１０５】
とすると
【０１０６】
Ｘ_ｉ＝Ｘ_Ｒ＋ｎＲｘ （４２）
Ｙ_ｉ＝Ｙ_Ｒ＋ｎＲｙ （４３）
Ｚ_ｉ＝Ｚ_Ｒ＋ｎＲｚ （４４）
Ｅ_２Ｘ_ｉ＋Ｆ_２Ｙ_ｉ＋Ｇ_２Ｚ_ｉ＋Ｈ_２＝０ （４５）
ただし、Ｅ_２、Ｆ_２、Ｇ_２、Ｈ_２は定数である。
【０１０７】
（４５）式に（４２）式、（４３）式、（４４）式を代入し整理する。
【０１０８】

【０１０９】
（４６）式よりｎを求め、（４２）式〜（４４）式に代入することで点Ｐｉの座標が求まる。
【０１１０】
このようにして最終的に結像面での座標が計算できる。このときレンズ作用は主光線のみを簡易的に考えれば結像面の像高に対して線形であると考える。結像面での座標を元にレンズの結像倍率から画像読取位置が計算される。
【０１１１】
一方、ミラーが傾いていない理想的な結像位置を計算し、その座標を元にレンズの結像倍率から理想状態の画像読取位置が計算される。この位置とミラーが傾いたときの画像読取位置の差を計算することで、原稿面での読取位置の変化が計算される。
【０１１２】
次に、図１５は本発明の画像位置補正方法の各実施例を実行するプログラムを起動するための具体的な装置の構成を示すブロック図である。つまり、同図は上記実施例における画像位置補正方法によるソフトウェアを実行するマイクロプロセッサ等から構築されるハードウェアを示すものである。同図において、画像位置補正システムはインターフェース（以下Ｉ／Ｆと略す）９１、ＣＰＵ９２、ＲＯＭ９３、ＲＡＭ９４、表示装置９５、ハードディスク９６、キーボード９７及びＣＤ−ＲＯＭドライブ９８を含んで構成されている。また、汎用の端末装置を用意し、ＣＤ−ＲＯＭ９９などの読取可能な記憶媒体には、本発明の画像位置補正方法を実行するプログラムが記憶されている。更に、Ｉ／Ｆ９１を介して外部装置から制御信号が入力され、キーボード９７によって操作者による指令又は自動的に本発明のプログラムが起動される。そして、ＣＰＵ９２は当該プログラムに従って上述の画像位置補正方法に伴う制御処理を施し、その処理結果をＲＡＭ９４やハードディスク９６等の記憶装置に格納し、必要により表示装置９５などに出力する。以上のように、本発明の画像位置補正方法を実行するプログラムが記憶した媒体を用いることにより、既存の端末装置を変えることなく、画像位置補正システムを汎用的に構築することができる。
【０１１３】
なお、本発明は上記実施例に限定されるものではなく、特許請求の範囲内の記載であれば多種の変形や置換可能であることは言うまでもない。
【０１１４】
【発明の効果】
以上説明したように、本発明の画像読取装置は、任意の被写体を照明する光源から出射した光を反射、集光する光学系部材を有する照明手段と、照明手段を被写体に対して相対的に走査させるために走査移動する第１の走行体と、被写体からの反射光を１次元に撮像する撮像素子と、被写体からの反射光を撮像素子に導く反射部材と、反射部材を搭載して第１の走行体と連動して移動する第２の走行体とを有し、第１の走行体が走査して撮像素子に被写体の像が結像することで被写体の画像を読み取る画像読取手段と、画像読取手段より出力される信号から画像信号を生成する信号処理手段とを含んで構成されている。そして、本発明の画像読取装置は、少なくとも１つの反射部材の走査変位を、少なくとも２点で計測する複数の変位計測手段を有することに特徴がある。よって、画像ゆらぎを補正でき、光学部材の傾きや振動による読取位置のずれを補正することができる。
【０１１５】
また、本発明の画像読取装置は、変位計測手段で計測されたデータを記憶し、計測された速度から反射部材の位置と傾きを求める演算処理部を有している。この演算処理部は、任意の瞬間の光学部材の位置と傾きから読取位置を計算し、光学部材の傾きや振動による読取位置のずれを補正する。よって、製造段階においては、光学部材の初期調整をする時間を短縮し、使用時では経時的な読取画像の劣化を補正することができる。
【０１１６】
更に、演算処理部により計測された変位から反射部材の位置と傾きを求め、計算された光束の反射方向と光束の伝播経路から結像レンズ毎の光束の屈折方向を計算し、主光線の伝播経路を計算して撮像素子上での結像位置を計算し、計算した結像位置から被写体上での読取位置の変化を計算し、読取位置のずれを補正する。よって、製造段階においては、光学部材の初期調整をする時間を短縮し、使用時では経時的な読取画像の劣化を補正することができる。
【０１１７】
また、別の発明としての画像読取装置における画像位置補正方法によれば、少なくとも１つの走行体の走査変位を、少なくとも２点で計測し、計測データを記憶し、計測された走査変位から光学系を構成する走行体の位置及び傾きを計算する。そして、走行体の位置及び傾きから、演算によって走行体に設置された反射部材の傾きを計算し、被写体からの反射光を撮像素子に導く反射部材の傾きによる光束の反射方向と光束の伝搬経路を計算する。更に、計算された光束の反射方向と光束の伝播経路から結像レンズ毎の光束の屈折方向を計算し、主光線の伝播経路を計算して撮像素子上での結像位置を計算する。そして、計算した結像位置から被写体上での読取位置の変化を計算し、任意の瞬間の光学部材の位置と傾きから、演算により読取位置を計算し、光学部材の傾きや振動による読取位置のずれを補正する。よって、画像ゆらぎを補正でき、光学部材の傾きや振動による読取位置のずれを補正することができ、製造段階においては光学部材の初期調整をする時間を短縮し、使用時では経時的な読取画像の劣化を補正することができる。
【０１１８】
更に、別の発明としての画像読取装置における画像位置補正方法によれば、少なくとも１つの反射部材の走査変位を、少なくとも２点で計測し、計測されたデータを記憶し、計測された変位から反射部材の位置と傾きを求める。そして、計算された光束の反射方向に対して逆方向に伝播する光束を計算し、反射部材の影響を受けない状態の被写体上での光束の出発点を求め、出射点からの主光線の伝播経路を計算することで撮像素子上での結像位置を計算する。更に、計算した結像位置から被写体上での読取位置の変化を計算し、光学部材の傾きや振動による読取位置のずれを補正する。よって、製造段階においては光学部材の初期調整をする時間を短縮し、使用時では経時的な読取画像の劣化を補正することができる。
【０１１９】
また、別の発明として、コンピュータで、上記画像読取装置における画像位置補正方法を実行するためのプログラムに特徴がある。よって、画像ゆらぎを補正でき、光学部材の傾きや振動による読取位置のずれを補正することができる画像位置補正方法を汎用的に画像読取装置に適用できる。
【０１２０】
更に、別の発明として、上記画像位置補正方法を実行するためのプログラムを格納したコンピュータ読み取り可能な記録媒体に特徴がある。よって、既存のシステムを変えることなく、画像位置補正方法を適用した画像読取装置を汎用的に構築することができる。
【図面の簡単な説明】
【図１】本発明に係る画像読取装置の構成を示す透視斜視図である。
【図２】図１の画像読取装置の構成を示す概略断面図である。
【図３】本発明の画像読取装置に設けられた変位計測装置の構成例を示す透視斜視図である。
【図４】別の発明の一実施例に係る画像位置補正方法を適用する画像位置補正回路の構成を示すブロック図である。
【図５】本実施例の画像位置補正装置の動作を示すフローチャートである。
【図６】反射ミラーの座標変換の概念を示す図である。
【図７】出射光束と反射の様子を示す図である。
【図８】出射光束と反射の様子を示す図である。
【図９】反射光束ベクトルＱ’’の位置及び方向の計算の一例を示す図である。
【図１０】レンズの屈折による結像位置算出手順を示す図である。
【図１１】主走査及び副走査方向に関して読取り位置の変化を示す図である。
【図１２】本実施例の画像位置補正装置を適用した読取位置評価装置の構成を示す透視斜視図である。
【図１３】別の画像位置補正の様子を示す図である。
【図１４】別の画像位置補正方法を説明する図である。
【図１５】本発明の画像位置補正方法の各実施例を実行するプログラムを起動するための具体的な装置の構成を示すブロック図である。
【符号の説明】
１０，４１；画像読取装置、１１；原稿設置場所、１２，１５；走行体、
１３；１次元撮像素子、１４；レンズ、１６；画像信号出力ポート、
１７；駆動手段、１８；コンタクトガラス、１９；原稿、２０；ランプ、
２１；撮像領域、３１〜３３；反射ミラー、３４；反射治具、
３５，３７；非接触変位計、３８；スライドレール、４２；データバス、
４３；画像演算部、４４；変位計測装置、４５；制御部、
４６；演算処理部、６１；原点平面、６２；原点、６３〜６５；反射面、
６６；結像レンズ、６７；結像面、７１；反射面、７２；レンズ面、
７３；レンズ、７４；結像面、８１；原稿面、８２〜８４；反射面、
８５；結像面、８６；結像レンズ、８７；主光線。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image reading apparatus, an image position correcting method in the image reading apparatus, a program for executing the method, and a computer-readable recording medium storing the program, and more particularly, to an image evaluation / use useful in a flatbed scanner. Regarding correction.
[0002]
[Prior art]
[Patent Document 1] JP-A-9-6827
[Patent Document 2] JP-A-2000-163567
Patent Document 1 proposes a method and apparatus for simulating an electronic image sensor having an image sensor, an optical system, and a processing circuit when performing useful image evaluation and correction in a flatbed scanner. The image is being calculated.
[0003]
Japanese Patent Application Laid-Open No. H11-163,873 discloses an image reading apparatus that scans a calibration plate having black stripes, calculates a deformation amount for each black stripe by comparing with a known physical position of the black stripe, and compensates for image distortion. A device has been proposed.
[0004]
[Problems to be solved by the invention]
However, in the conventional image reading apparatuses described in Patent Documents 1 and 2, the output position of the image is shifted from the original output position due to mechanical factors such as vibration caused by scanning of the traveling body or positioning error of the optical member. There is image fluctuation. Also, in the manufacturing stage, in the inspection process, the optical member was adjusted, a read image of the actual machine was acquired, the obtained image was evaluated, and the repetitive work of performing the adjustment was performed, which was time-consuming. . Furthermore, the user only obtains an image at a fixed position and does not see the image of the entire document. Further, a minute positional shift of the optical member may occur due to a change with time, which may affect an image.
[0005]
The present invention has been made to solve these problems. An image reading apparatus capable of correcting image fluctuation, shortening adjustment time in a manufacturing stage, and correcting deterioration of a read image over time during use. It is an object to provide a device, an image position correcting method in an image reading device, a program for executing the method, and a computer-readable recording medium storing the program.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, an image reading apparatus according to the present invention includes: an illumination unit having an optical system member that reflects and collects light emitted from a light source that illuminates an arbitrary subject; Equipped with a first traveling body that scans and moves to relatively scan, an imaging device that one-dimensionally captures reflected light from a subject, a reflecting member that guides reflected light from the subject to the imaging device, and a reflecting member And a second traveling body that moves in conjunction with the first traveling body, wherein the first traveling body scans and forms an image of the subject on the image sensor to read the image of the subject. The image processing apparatus includes a reading unit and a signal processing unit that generates an image signal from a signal output from the image reading unit. Further, the image reading apparatus of the present invention is characterized in that it has a plurality of displacement measuring means for measuring the scanning displacement of at least one reflecting member at at least two points. Therefore, the image fluctuation can be corrected, and the deviation of the reading position due to the inclination or vibration of the optical member can be corrected.
[0007]
Further, the image reading apparatus of the present invention has an arithmetic processing unit which stores data measured by the displacement measuring means and calculates the position and inclination of the reflecting member from the measured speed. The arithmetic processing unit calculates the reading position from the position and the inclination of the optical member at an arbitrary moment, and corrects the deviation of the reading position due to the inclination and vibration of the optical member. Therefore, in the manufacturing stage, the time for the initial adjustment of the optical member can be shortened, and the deterioration of the read image over time can be corrected in use.
[0008]
Further, the position and inclination of the reflecting member are obtained from the displacement measured by the arithmetic processing unit, and the refraction direction of the light beam for each imaging lens is calculated from the calculated reflection direction of the light beam and the propagation path of the light beam. A path is calculated to calculate an image forming position on the image sensor, a change in a reading position on the subject is calculated from the calculated image forming position, and a deviation of the reading position is corrected. Therefore, in the manufacturing stage, the time for the initial adjustment of the optical member can be shortened, and the deterioration of the read image over time can be corrected in use.
[0009]
Further, according to the image position correcting method in the image reading device as another invention, the scanning displacement of at least one traveling body is measured at at least two points, the measurement data is stored, and the optical system is calculated from the measured scanning displacement. Is calculated. Then, from the position and the inclination of the traveling body, the inclination of the reflecting member installed on the traveling body is calculated by calculation, and the reflection direction of the light beam and the propagation path of the light beam due to the inclination of the reflecting member that guides the reflected light from the subject to the image sensor. Is calculated. Further, the refraction direction of the light beam for each imaging lens is calculated from the calculated reflection direction of the light beam and the propagation path of the light beam, and the propagation path of the principal ray is calculated to calculate the image formation position on the image sensor. Then, the change of the reading position on the subject is calculated from the calculated image forming position, and the reading position is calculated by calculation from the position and inclination of the optical member at an arbitrary moment, and the reading position due to the inclination and vibration of the optical member is calculated. Correct the misalignment. Therefore, the image fluctuation can be corrected, the reading position shift due to the inclination or vibration of the optical member can be corrected, the time for the initial adjustment of the optical member can be reduced in the manufacturing stage, and the read image can be read with time in use. Can be corrected.
[0010]
Further, according to the image position correcting method in the image reading device as another invention, the scanning displacement of at least one reflecting member is measured at at least two points, the measured data is stored, and the reflection is measured from the measured displacement. Find the position and inclination of the member. Then, the light beam propagating in the opposite direction to the calculated light beam reflection direction is calculated, the starting point of the light beam on the subject not affected by the reflection member is obtained, and the propagation of the principal ray from the emission point is calculated. By calculating the path, an image formation position on the image sensor is calculated. Further, a change in the reading position on the subject is calculated from the calculated image forming position, and a deviation of the reading position due to the inclination or vibration of the optical member is corrected. Therefore, it is possible to shorten the time required for the initial adjustment of the optical member in the manufacturing stage, and to correct the deterioration of the read image with time during use.
[0011]
Another aspect of the present invention is characterized in a program for causing a computer to execute the image position correcting method in the image reading device. Therefore, an image position correction method capable of correcting image fluctuation and correcting a shift of a reading position due to inclination or vibration of an optical member can be generally applied to an image reading apparatus.
[0012]
Another aspect of the present invention is characterized in a computer-readable recording medium storing a program for executing the image position correcting method. Therefore, an image reading apparatus to which the image position correction method is applied can be universally constructed without changing an existing system.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The image reading apparatus of the present invention has a plurality of displacement measuring means for measuring the scanning displacement of at least one reflecting member at at least two points.
[0014]
【Example】
FIG. 1 is a perspective view showing the configuration of the image reading apparatus according to the present invention. FIG. 2 is a schematic sectional view showing the configuration of the image reading apparatus of FIG.
[0015]
First, the configuration of the image reading apparatus according to the present invention will be described with reference to FIG. 1. The image reading apparatus 10 according to the present invention includes a document placing place 11 which is a platen on which an image original is placed, and a document placing place 11. A traveling body 12 that scans in the sub-scanning direction, a one-dimensional image sensor 13 of, for example, a line CCD, which forms a line in a direction perpendicular to the traveling body 12, and a lens that couples an image on the one-dimensional image sensor 13 to a document setting place 11 A traveling body 15 for scanning in the sub-scanning direction following the traveling body 12 and appropriately forming a reflected image from the document on the one-dimensional image sensor 13 via the lens 14; Scans the document setting place 11 in the sub-scanning direction, thereby taking in an image line-sequentially the image set in the document setting place 11, reads the image as a two-dimensional image by scanning, and outputs the image signal. output And over bets 16, it is configured to include a driving means 17 for driving the traveling member 12, 15. Note that the image reading apparatus 10 in FIG. 1 is a scanning unit scanning type flat type scanner, but need not be limited to this, and may be an original platen scanning type or relative scanning type scanner. Further, an image forming apparatus such as a digital camera may be used. Further, the image resolution of the one-dimensional image sensor 13 does not match the image resolution of the flatbed scanner itself. Normally, the image resolution of a flatbed scanner is represented by DPI (dot / inch), and is about 300 to 800 DPI.
[0016]
Next, the operation of the image reading apparatus according to the present invention will be described with reference to FIG. 2. A reference document 19 is set on a contact glass 18, and a lamp 20 as a light source for illuminating the document 19 is reflected by a reflector. To irradiate the imaging area 21 with light. Then, the traveling body 15 and the traveling body 12 following the traveling body 15 scan from the top to the end of the document 19, so that the reflected light passes through the folding mirrors 12-1 and 15-1 and the lens 14, and the one-dimensional imaging device 13 , A series of operations are performed on the entire surface of the document, the image signal is captured as a two-dimensional image signal, and output from the image signal output port 16 in FIG.
[0017]
FIG. 3 is a perspective view showing a configuration example of a displacement measuring device provided in the image reading apparatus of the present invention. 2, the same reference numerals as those in FIG. 2 denote the same components. The displacement measuring device 30 in the figure attaches a reflection jig 34 to both ends of a reflection mirror 31, a reflection mirror 32, or a reflection mirror 33, applies measurement light 36 of a non-contact displacement meter 35 to the reflection jig 34, The displacement meter 35 is set so that light returns again. Thereby, the displacement in the sub-scanning direction can be measured. The non-contact displacement meter 35 is fixed to a housing of the image reading device. On the other hand, non-contact displacement gauges 37 are attached to both ends of the reflection mirror 31, the reflection mirror 32, or the reflection mirror 33, and the measuring light 36 is applied to the slide rail 38 in a direction perpendicular to the sub-scanning direction. Set the light back. Thereby, the displacement in the direction perpendicular to the sub-scanning direction can be measured.
[0018]
Since the reflection jig 34 and the non-contact displacement meter 37 affect the deflection and behavior of the reflection mirror, the reflection jig 34 and the non-contact displacement meter 37 should be as small as possible, or should be directly attached to the reflection mirror. Further, in order to measure the inclination of the minute reflecting mirror, it is preferable that the distance between the two reflecting jigs 34 or the non-contact displacement gauge 37 is as far as possible. Furthermore, in order to obtain the partial tilt of the reflecting mirror in the sub-scanning direction, three or more reflecting jigs are attached, and the partial tilt between the jigs is calculated, thereby more accurately measuring the tilt of the reflecting mirror. Becomes possible. As the non-contact displacement meter, a displacement measuring device such as a laser length measuring device, a capacitance type, and an eddy current type can be used. In the case of the laser type, it is necessary to increase the reflectance of the reflection jig 34 and the slide rail 38. When a capacitance type or eddy current type non-contact displacement meter is used, the reflecting jig 34 and the slide rail 38 need to be made of conductive metal surfaces. Further, a small laser Doppler vibrometer can be used instead of the non-contact displacement meter. In this case, calculation is performed after integrating the measured speed fluctuation data and converting it into displacement. Further, the acceleration may be measured by an acceleration pickup. In this case, the acceleration pickup is directly fixed to the reflection mirror. When measuring the acceleration, it is necessary to convert it into a displacement by integrating the second order.
[0019]
Next, FIG. 4 is a block diagram showing a configuration of an image position correction circuit to which an image position correction method according to another embodiment of the present invention is applied. As shown in the figure, the image reading device 41 is connected to a data bus 42, has a function capable of scanning by a trigger signal, and sends out an image signal. An image calculation unit 43 for calculating an image signal is connected to the data bus 42. The image calculation unit 43 performs image processing based on the image signal, and calculates final image data. A displacement measuring device 44 composed of the non-contact displacement meters 35 and 37 and the reflecting jig 34 shown in FIG. 3 is a device for measuring the displacement of a reflecting mirror that is moved by scanning of the image reading device 41, and a control unit 45 includes an arithmetic processing unit. 46, and further connected to the data bus 42. The arithmetic processing unit 46 is constituted by a computer, issues a data acquisition command to the control unit 45 in synchronization with the scanning signal sent from the image reading device 41 through the data bus 42, and outputs the data to the non-contact displacement meters 35 and 37 in FIG. To obtain data. The data measured by the displacement meter is converted into an electric signal by the control unit 45, amplified, and sent to the arithmetic processing unit 46 as displacement data. At this time, it is necessary to select a non-contact displacement meter having a higher response frequency than the scanning frequency calculated from the scanning time of one row and the CCD pixel size converted on the document surface. The arithmetic processing unit 46 has a function of storing displacement data. Further, it has a function of performing a calculation based on the received displacement data, calculating a reading position of the document image, and correcting the reading position of the image data calculated by the image calculation unit 43.
[0020]
Next, FIG. 5 is a flowchart showing the operation of the image position correcting apparatus of the present embodiment. 4, first, when a drive command is issued to the image reading device 41 in FIG. 4, a data acquisition command is also issued to the displacement measuring device 44 in FIG. 4, and the image reading device 41 starts scanning (step S1). S101). The displacement measuring device 44 starts measuring the displacement of the reflection mirror (steps S102 and S103). The scanning order of the arithmetic processing unit 46 in FIG. 4 is counted by a column counter. The column counter and the displacement data transferred from the displacement measuring device 44 are stored as a pair in a storage device in the arithmetic processing unit 46 (steps S104 to S106). When the image reading device 41 scans the entire area (step S107; YES), the measurement ends. The data stored in the arithmetic processing unit 46 is converted into displacement data by integrating once for velocity data and twice for acceleration. When the displacement data is measured, it remains as it is. The tilt amount of the mirror is calculated from the displacement data and the distance between the two reflecting jigs. Since the running bodies 12 and 13 in FIG. 4 are driven by the same wire or belt, the speed of the running body 12 is twice as high as the speed of the running body 13. Therefore, for example, the displacement of the reflection mirror 31 has twice the displacement of the measured displacement of the reflection mirror 32. The image reading position is calculated by performing coordinate transformation and geometrical optics calculation based on the distance between the mirrors and the inclination obtained in this manner (steps S108 to S111). Details of the calculation will be described later. The ideal image reading position when the reflection mirror is not tilted is calculated from the design data of the optical system. This can be obtained from the design magnification of the lens, or can be calculated by the ray tracing method described below. It is desirable that an ideal image reading position corresponding to each column is calculated in advance and prepared as a data table in the arithmetic processing unit 46 in FIG. Based on the ideal image reading position, the reading position deviation is calculated by calculating the difference between the image reading position when the mirror is tilted and the position corresponding to the column counter. Furthermore, the final image position can be corrected by subtracting the read position shift calculated above from the image position data corresponding to each column counter calculated by the image calculation unit 43 in FIG. 4 (step S112). , S113). This calculation is sequentially performed until the end of the measurement data based on the value of the column counter (step S114). These calculations are performed by software incorporated in the arithmetic processing unit 46.
[0021]
Here, the change in the imaging position due to the mirror position and the mirror tilt is often calculated by a ray tracing method. However, many ray tracing software are general-purpose software, and it has been difficult to use them in combination with other measurement systems. Therefore, ray tracing is performed by making the relationship between the incident light flux due to the position of the reflection mirror and the inclination of the reflection mirror and the light flux reflected on the reflection mirror surface into a general geometric optical formula.
[0022]
FIG. 6 is a diagram illustrating the concept of coordinate conversion of a reflection mirror. 4, an origin 62 and an origin plane 61 including the origin 62 are considered, and respective orthogonal coordinate systems are determined as shown in FIG. Here, it is assumed that the origin plane 61 is equal to the document surface. When the reflection mirror is considered as the reflection surface 63, it can be considered that the reflection surface constituting the image reading apparatus rotates β around the Z axis and moves K2 in the Y axis direction and K1 in the X axis direction. At this time, the reflection surface slightly rotates around the Y axis due to the inclination of the reflection mirror. Also, rotation around the X axis is taken into account. These can be considered as three-dimensional affine transformations. If a certain point [x, y, z, 1] on the origin plane 41 is expressed as a fourth-order homogeneous coordinate system, and the converted coordinates are [xR, yR, zR, 1],
[0023]
[XR, yR, zR, 1] = [x, y, z, 1] [C] (1)
[0024]
Is represented by Here, [C] is a rotation and translation sequence, and is expressed as follows.
[0025]
(Equation 1)

[0026]
Next, as shown in FIG. 7 showing the state of the emitted light beam and reflection, it is considered where the emitted light beam vector emitted from a certain point P (xs, ys, zs) on the origin plane 61 hits the reflection surface. It is assumed that the emitted light beam vector travels in the unit vector Q direction, is reflected at a point K (xp, yp, zp), and is reflected in the reflected light beam vector Q ′ direction. If PK = 1, the following simultaneous equations hold.
[0027]
xp = xs + 1Qx (3)
yp = ys + 1Qy (4)
zp = zs + 1Qz (5)
Exp + Fyp + Gzp + H = 0 (6)
[0028]
Here, equation (6) is an equation of the reflecting surface, and E, F, G, and H are constants.
By substituting Equations (3), (4), and (5) into Equation (6) and rearranging, the following equation is obtained.
[0029]
1 =-(xsE + ysF + zsG + H) / (QxE + QyF + QzG)
(7)
[0030]
By substituting the obtained l into the equations (3) to (5), the coordinates of the point K can be obtained.
[0031]
On the other hand, the reflection normal unit vector E ′ can be expressed as follows using the normal vector E of the emission surface.
[0032]
E '= CE (8)
[0033]
When the unit vector [Qx, Qy, Qz] of the emitted light beam vector is used, the reflected light beam vector [Q'x, Q'y, Q'z] indicating the reflection direction is expressed as follows using a reflection matrix. Can be.
[0034]
(Equation 2)

[0035]
Next, as shown in FIG. 8 showing the state of the emitted light beam and the reflection, the emitted light beam unit vector Q ′ emitted from the point K on the reflecting surface 63 hits the point M on the reflecting surface 64 and the reflected light beam vector Q ″ Reflect in the direction. This means that the position and direction of the reflected light beam vector Q ″ can be obtained by performing the calculations of the above equations (1) to (9).
[0036]
The above-described series of calculations is sequentially performed on each reflecting surface. FIG. 9 shows an example of the series of calculations. In the figure, a light beam emitted from a point P on the original plane 61 hits a point K on the reflection surface 63, is reflected, hits a point M on the reflection surface 64, and is reflected in the direction of Q ''. Further, the light impinges on a point N on the reflection surface 65 and is reflected in the Q ′ ″ direction. The refraction effect of the imaging lens 66 is often calculated by a ray tracing technique.
[0037]
However, many ray tracing software are general-purpose software, and it has been difficult to use them in combination with other measurement systems. In addition, conventional software is described as a combination of refraction at a refraction interface, and it is not possible to calculate a lens unit of a component.
[0038]
Therefore, the refraction of each imaging lens is represented by a general geometric formula, and the ray tracing of the light beam passing through the imaging lens is performed to obtain an imaging position. The inclination and translation of the imaging lens are determined by the assembly accuracy of the imaging lens itself and the assembly accuracy to the image reading device. The reflection eccentricity or the transmission eccentricity of the imaging lens itself can be measured by a lens eccentricity measuring device or the like, and the mounting to the image reading device is determined by the accuracy of the mounting jig. In practice, it is better to calculate in consideration of the stacking tolerance of the inclination / translation tolerance of the imaging lens itself and the assembly tolerance to the image reading device, and to estimate the final reading position error.
[0039]
Next, a procedure for calculating an imaging position by refraction of a lens will be described with reference to FIGS.
As shown in FIG. 10A, the output light unit vector S (= Q ′ ″) reflected from the point V (Vx, Vy, Vz) on the reflection surface 71 has an intersection K (Xk, Yk, Zk). The coordinates of K and the refraction direction at this time are obtained. It is assumed that the lens surface 72 is rotated or translated with respect to the original coordinate system. This is to take into account lens mounting errors. In this case, coordinate conversion is performed by adjusting the coordinate system to the rotation or translation of the lens surface 72 as shown in FIG. There is also a method of considering rotation or translation of the lens surface while keeping the original coordinate system. However, considering the case where the lens surface is aspherical, the calculation formula is simplified when the calculation is performed after conversion to the conversion coordinate system. The original coordinate system is XYZ, the rotations around the respective axes are γ, α, β, and the translations are Ux, Uy, Uz. FIGS. 10A and 10B show a state where the rotation angle is β and the translation amount is Uy. When the translation and rotation components are added, the point V ′ (V′x, V′y, V′z) and the output light vector S ′ (S′x, S′y, S′z) after the coordinate transformation are as follows. Is expressed as follows.
[0040]
[V'x V'y V'z] = [Vx-Ux Vy-Uy Vz-Uz] [R] (10)
[S'xS'yS'z] = [SxSySz] [R] (11)
[0041]
Here, [R] is a rotation matrix, and is expressed as follows.
[0042]
[Equation 3]

[0043]
The output light vector S 'is not affected by translation, so that only the rotation matrix acts.
[0044]
Next, an intersection K ′ (X′k, Y′k, Z′k) between the emitted light and the lens surface 72 in the transformed coordinate system is determined.
[0045]
(Equation 4)

[0046]
Then, the following simultaneous equations hold.
[0047]
X'k = V'x + mS'x (13)
Y'k = V'y + mS'y (14)
Z'k = V'z + mS'z (15)
[0048]
(Equation 5)

[0049]
Here, equation (16) is an equation of an aspherical curved surface. Cn is a Conic constant, and the shape of the curved surface changes according to the value of Cn. (Cn> 0: ellipse, Cn = 0: paraboloid, Cn <0: hyperboloid, Cn = 1: spherical surface) r is the radius of curvature of the lens surface 1.
[0050]
The coordinates of the intersection K ′ can be obtained by solving the above equations (13) to (16) to obtain m, and substituting it into the equations (13) to (15).
[0051]
Next, the refraction direction on the lens surface is calculated. As shown in FIG. 10C, the outgoing light vector V ′ propagates through the medium having the refractive index N, and is refracted by the lens surface 72 having the refractive index N ′, so that the refracted light vector T ′ (T′x, T'y, T'z).
[0052]
Then, as shown in FIG. 10D, the normal vector E ′ (E′x, E′y, E′z) on the lens surface 72 at the intersection K ′ is considered. At this time, the angle of incidence on the lens surface 72 is i, and the angle between the refracted light vector and the normal vector is i ′. By transforming equation (16) with respect to X'k, the following equation (17) is obtained.
[0053]
(Equation 6)

[0054]
Each component of the normal vector can be calculated by taking a gradient.
[0055]
(Equation 7)

[0056]
Is as follows.
[0057]
E'x = 1 (19)
E'y = -Y'k / Br (20)
E'z = -Z'k / Br (21)
Snell's law using the relations E'.S '= cos i and E'.T' = cos i '
[0058]
| N | (E ′ × S ′) = | N ′ | (E ′ × T ′) (22)
[0059]
Is transformed, the refracted light vector T ′ (T′x, T′y, T′z) is obtained as follows.
[0060]
T ′ = NS ′ / N ′ + E ′ (cos i′−Ncos i / N ′) (23)
Here, cos i ′ can be calculated as follows.
[0061]
(Equation 8)

[0062]
sign (cos i) is a function that takes a value of +1 or −1 depending on the sign of cos i.
[0063]
Using the equations (10) to (24), the intersection point K ′ on the lens surface 72 and the refracted light vector T ′ are obtained. These series of calculations are similarly performed for the next surface.
[0064]
As shown in FIG. 10- (e), a lens surface 73 is considered behind the lens surface 72. If a lens is present, the intersection K ′ determined above is the emission point coordinates, and the refracted light vector T ′ is the emitted light vector. The refraction calculation of the lens is performed by performing the same calculation in consideration of the above.
In this way, the intersection K′1 (X′k1, Y′k1, Z′k1) and the refracted light vector T′1 (T′x1, T′y1, T′z1) finally emitted from the lens are obtained. .
[0065]
Next, as shown in FIG. 10- (f), the coordinate system X′Y′Z ′ is returned to the original coordinate system XYZ. Assuming that the rotation matrix is [R], when only the lens inclination is returned to the original coordinate system, the following is obtained.
[0066]
[Xs Ys Zs] = [R] ^-1 [X'k1 Y'k1 Z'k1] (25)
[0067]
At this time, [R] ^-1 Is given as
[0068]
(Equation 9)

[0069]
If the translation component is restored, the intersection K1 becomes as follows.
[0070]
[Xk1 Yk1 Zk1] = [Xs + Ux Ys + Uy Zs + Uz] (27)
[0071]
The refracted light vector T1 can be returned to the original coordinate system as follows.
[0072]
[Tx1 Ty1 Tz1] = [R] ^-1 [T'x1 T'y1 T'z1] (28)
[0073]
Since the refracted light vector T1 is not affected by translation, only the rotation matrix acts.
[0074]
In this way, the refraction at the lens can be calculated. Even in the case where there are a plurality of lenses, the calculation can be performed by repeatedly executing the calculations of the equations (10) to (28).
[0075]
Next, the coordinates of the imaging position are obtained. The imaging position Pi [Xi, Yi, Zi] on the imaging surface 74 is
[0076]
(Equation 10)

[0077]
Then, the following simultaneous equations hold.
[0078]
Xi = Xk1 + nTx1 (29)
Yi = Yk1 + nTy1 (30)
Zi = Zk1 + nTz1 (31)
E ₂ Xi + F ₂ Yi + G ₂ Zi + H ₂ = 0 (32)
Where E ₂ , F ₂ , G ₂ , H ₂ Is a constant.
[0079]
The equations (29), (30), and (31) are substituted into the equation (32), and rearranged to obtain n.
The coordinates of the imaging position Pi [Xi, Yi, Zi] can be obtained by substituting the obtained n into the expressions (29) to (31). In this way, the coordinates on the image plane can be finally calculated. The image reading position is calculated based on the image forming magnification of the lens based on the coordinates on the image forming plane. Assuming that the imaging magnification of the lens is V, the image reading position [Xg, Yg, Zg] can be calculated as follows.
[0080]
Xg = Xi / V (33)
Yg = Yi / V (34)
Zg = Zi / V (35)
[0081]
In addition, since the propagation of light rays is reversible, ray tracing can be performed from the image forming surface side to calculate an image reading position. If only the principal ray is considered, this method can directly determine the image reading position.
[0082]
Next, as shown in FIG. 3, the reflecting jigs 34 are attached to both ends of the reflecting mirror 32, the measuring light 36 of the non-contact displacement meter 35 is applied to the reflecting jig 35, and the light returns to the non-contact displacement meter 35 again. Set to. Thus, the displacement in the sub-scanning direction is measured, and the inclination of the reflection mirror 32 in the sub-scanning direction is calculated. It is assumed that the reflection mirror 33 has a similar inclination. Although it is considered that the reflection mirror 31 has twice the displacement of the reflection mirror 32, it is desirable to measure the displacement of the reflection mirror 31 accurately. On the other hand, non-contact displacement gauges 37 are attached to both ends of the reflection mirror 32, and the measuring light 36 is applied to the slide rail 38 in a direction perpendicular to the sub-scanning direction so that the light returns to the non-contact displacement gauge 37 again. Thereby, the displacement in the vertical direction with respect to the sub-scanning direction is measured, and the inclination is calculated. It is assumed that the reflection mirror 33 has a similar inclination. Although it is considered that the reflection mirror 31 has twice the displacement of the reflection mirror 32, it is desirable to measure the displacement of the reflection mirror 31 accurately.
[0083]
FIG. 11 shows a series of the above-described series of measurements and calculations performed over the entire scanning range of the A3 document and plotting the change in the reading position in the main scanning and sub-scanning directions. The left table shows the inclination amount of the reflection mirror 31 in FIG. 3 at the sub-scanning position. This indicates that the reading position changes due to the inclination of the reflection mirror fluctuating with scanning, and image fluctuation occurs. The image fluctuation amount in this figure is displayed in an enlarged manner in the main scanning and sub-scanning directions. When the image fluctuation is corrected over the entire surface of the document, a rectangular result is obtained.
[0084]
FIG. 12 is a perspective view showing the configuration of a reading position evaluation device to which the image position correction device of this embodiment is applied. 3, the same reference numerals as those in FIG. 3 indicate the same components. Here, in order to measure the behavior of the reflection mirror 32, it is preferable to attach a reflection jig 34 to the reflection mirror 32. However, since the traveling body 13 is present, the reflection jig is It is difficult to install. Therefore, the reflection jig 34 is attached to the traveling body 12 or the traveling body 13. In the example shown in the figure, a reflecting jig 34 is attached to the traveling body 13. The measuring light of the non-contact displacement meter 35 is applied to the reflection jig 34, and the light is returned to the non-contact displacement meter 35 again. Thereby, the displacement in the sub-scanning direction can be measured. The non-contact displacement meter 35 is fixed to a housing of the image reading device. The reflection mirrors 32 and 33 are attached to the traveling body 13, and the traveling body 13 may be considered as a rigid body. That is, it may be considered that the reflection mirrors 32 and 33 move in the same phase as the traveling body 13.
[0085]
On the other hand, non-contact displacement meters 37 are attached to both ends of the traveling body 12 or the traveling body 13, and the measuring light 36 is applied to the slide rail 38 in a direction perpendicular to the sub-scanning direction so that the light returns to the non-contact displacement meters 37 again. Set to. In this example, a non-contact displacement meter is attached to the traveling body 13. Thereby, the displacement in the direction perpendicular to the sub-scanning direction can be measured. In this case as well, the traveling body and the reflection mirror are considered to move in the same manner, and thus this displacement may be considered to correspond to the displacement of the reflection mirror. The reflection jig 34 and the non-contact displacement gauge 37 should be as small as possible because the mass of the reflection jig itself affects the deflection and behavior of the traveling body. In order to measure the inclination of a minute traveling body, two reflection jigs are used. Alternatively, it is better to separate the non-contact displacement meters 37 as much as possible. Furthermore, in order to obtain a partial inclination of the traveling body in the sub-scanning direction, three or more reflecting jigs are attached, and a partial inclination between the jigs is calculated, so that more accurate inclination measurement of the traveling body is performed. Becomes possible.
[0086]
In addition, the eigenmode of the traveling body alone can be measured or calculated, and the movement of the reflection mirrors 32 and 33 can be estimated from the behavior and the phase of the mounting portion of the reflection mirrors 32 and 33. In this case, it is possible to grasp the relative behavior of the reflection mirrors 32 and 33 by using the primary mode having the largest amplitude. The behavior of the eigenmode can be captured using finite element analysis or modal analysis.
[0087]
As the non-contact displacement meter, a displacement measuring device such as a laser length measuring device, a capacitance type, and an eddy current type can be used. In the case of the laser type, it is necessary to increase the reflectance of the reflection jig and the slide rail. When a capacitance type or eddy current type displacement meter is used, it is necessary to make the reflecting jig and the slide rail a conductive metal surface. Further, a small laser Doppler vibrometer can be used instead of the displacement meter. In this case, calculation is performed after integrating the measured speed fluctuation data and converting it into displacement. Further, the acceleration may be measured by an acceleration pickup. In this case, the acceleration pickup is directly fixed to the reflection mirror. When measuring the acceleration, it is necessary to convert it into a displacement by integrating the second order.
[0088]
Next, another image position correcting operation of the image position correcting apparatus of the present embodiment will be described. Another image position correcting method is the same as the above-described operation up to the ray tracing portion up to the reflection mirror. The calculation part of the refraction action by the imaging lens thereafter is different. In many cases, the refraction effect of the imaging lens performs refraction calculation for each lens by a ray tracing technique. In addition, since the lens itself is fixed to the housing, if the positioning is accurate, the tilt and translation are minute and do not change with time. If only the chief ray is considered in such a state, the refraction effect of the lens can be calculated by the following method.
[0089]
FIG. 13 is a diagram showing another image position correction. Here, for convenience of explanation, the description will be made with the optical path arranged in a straight line. As shown in FIG. 13A, the reflected light unit vector Q ′ ″ reflected from the point N on the reflection surface 83 forms an image on a point Pi on the imaging surface 85. The coordinates of this Pi are obtained. Next, as shown in FIG. 13 (b), a backpropagating unit vector is generated in a direction opposite to the reflected light unit vector Q ′ ″.
[0090]
[Equation 11]

[0091]
In consideration of the above, the coordinates of the emission point R on the document surface 81 are obtained by ray tracing with the reflection surfaces 82 and 83 removed. A principal ray 87 passing from the exit point R to the center of the imaging lens 86 forms an image on a point Pi on the imaging plane 85. That is, the reflected light unit vector Q ′ ″ and the principal ray 87 form an image at the same point Pi. This utilizes the fact that the imaging relationship is not broken if the inclination of the reflection surface 81 is small. Therefore, as shown in FIG. 13 (c), the unit vector of the principal ray 87 emitted from the emission point R is traced, and the imaging position Pi is obtained, whereby the imaging position of the reflected light unit vector Q ′ ″ is obtained. Can be requested.
[0092]
FIG. 14 is a diagram for explaining another image position correction method. In the figure, the emission point on the document surface 81 can be calculated from the equation of the document surface plane and the back propagation unit vector. The equation for the document plane is obtained as follows.
[0093]
E ₁ X _R + F ₁ Y _R + G ₁ Z _R + H ₁ = 0 (36)
Where E ₁ , F ₁ , G ₁ , H ₁ Is a constant.
[0094]
Next, the coordinates of the emission point R are obtained. From point T (Xt, Yt, Zt)
[0095]
(Equation 12)

[0096]
The light emitted in the direction strikes an emission point R (XR, YR, ZR) on the document surface.
[0097]
(Equation 13)

[0098]
And
[0099]
[Equation 14]

[0100]
Then, the following equation is established.
[0101]
(Equation 15)

[0102]
Expressions (37), (38), and (39) are substituted into expression (40) and arranged.
(Equation 16)

[0103]
The coordinates of the point R are obtained by obtaining m from Expression (41) and substituting it into Expressions (37) to (39). By the same procedure, the imaging position (Xi, Yi, Zi) at which the two principal ray vectors (Rx, Ry, Rz) emitted from the emission point (XR, YR, ZR) are formed can be obtained.
[0104]
[Equation 17]

[0105]
Then
[0106]
X _i = X _R + NRx (42)
Y _i = Y _R + NRy (43)
Z _i = Z _R + NRz (44)
E ₂ X _i + F ₂ Y _i + G ₂ Z _i + H ₂ = 0 (45)
Where E ₂ , F ₂ , G ₂ , H ₂ Is a constant.
[0107]
The formulas (42), (43), and (44) are substituted into the formula (45) and arranged.
[0108]

[0109]
The coordinates of the point Pi are obtained by obtaining n from Expression (46) and substituting it into Expressions (42) to (44).
[0110]
In this way, the coordinates on the image plane can be finally calculated. At this time, it is considered that the lens action is linear with respect to the image height of the imaging plane if only the principal ray is simply considered. The image reading position is calculated based on the image forming magnification of the lens based on the coordinates on the image forming plane.
[0111]
On the other hand, an ideal imaging position where the mirror is not tilted is calculated, and an image reading position in an ideal state is calculated from the imaging magnification of the lens based on the coordinates. By calculating the difference between this position and the image reading position when the mirror is tilted, the change in the reading position on the document surface is calculated.
[0112]
Next, FIG. 15 is a block diagram showing the configuration of a specific device for activating a program for executing each embodiment of the image position correcting method of the present invention. That is, FIG. 7 shows hardware constructed from a microprocessor or the like that executes software according to the image position correction method in the above embodiment. In the figure, the image position correction system includes an interface (hereinafter abbreviated as I / F) 91, a CPU 92, a ROM 93, a RAM 94, a display device 95, a hard disk 96, a keyboard 97, and a CD-ROM drive 98. Also, a general-purpose terminal device is prepared, and a readable storage medium such as the CD-ROM 99 stores a program for executing the image position correcting method of the present invention. Further, a control signal is input from an external device via the I / F 91, and the keyboard 97 activates a command of the operator or the program of the present invention automatically. Then, the CPU 92 performs control processing according to the above-described image position correction method according to the program, stores the processing result in a storage device such as the RAM 94 or the hard disk 96, and outputs it to the display device 95 or the like as necessary. As described above, by using the medium in which the program for executing the image position correcting method of the present invention is stored, an image position correcting system can be universally constructed without changing an existing terminal device.
[0113]
It should be noted that the present invention is not limited to the above embodiment, and it goes without saying that various modifications and substitutions can be made within the scope of the claims.
[0114]
【The invention's effect】
As described above, the image reading apparatus of the present invention includes an illumination unit having an optical system member that reflects and condenses light emitted from a light source that illuminates an arbitrary subject, and the illumination unit relatively to the subject. A first traveling body that scans and moves for scanning, an imaging device that one-dimensionally captures reflected light from the subject, a reflecting member that guides the reflected light from the subject to the imaging device, An image reading means having a second traveling body that moves in conjunction with the first traveling body, wherein the first traveling body scans and forms an image of the subject on the image sensor to form an image of the subject; and And a signal processing means for generating an image signal from a signal output from the image reading means. Further, the image reading apparatus of the present invention is characterized in that it has a plurality of displacement measuring means for measuring the scanning displacement of at least one reflecting member at at least two points. Therefore, the image fluctuation can be corrected, and the deviation of the reading position due to the inclination or vibration of the optical member can be corrected.
[0115]
Further, the image reading apparatus of the present invention has an arithmetic processing unit which stores data measured by the displacement measuring means and calculates the position and inclination of the reflecting member from the measured speed. The arithmetic processing unit calculates the reading position from the position and the inclination of the optical member at an arbitrary moment, and corrects the deviation of the reading position due to the inclination and vibration of the optical member. Therefore, in the manufacturing stage, the time for the initial adjustment of the optical member can be shortened, and the deterioration of the read image over time can be corrected in use.
[0116]
Further, the position and inclination of the reflecting member are obtained from the displacement measured by the arithmetic processing unit, and the refraction direction of the light beam for each imaging lens is calculated from the calculated reflection direction of the light beam and the propagation path of the light beam. A path is calculated to calculate an image forming position on the image sensor, a change in a reading position on the subject is calculated from the calculated image forming position, and a deviation of the reading position is corrected. Therefore, in the manufacturing stage, the time for the initial adjustment of the optical member can be shortened, and the deterioration of the read image over time can be corrected in use.
[0117]
Further, according to the image position correcting method in the image reading device as another invention, the scanning displacement of at least one traveling body is measured at at least two points, the measurement data is stored, and the optical system is calculated from the measured scanning displacement. Is calculated. Then, from the position and the inclination of the traveling body, the inclination of the reflecting member installed on the traveling body is calculated by calculation, and the reflection direction of the light beam and the propagation path of the light beam due to the inclination of the reflecting member that guides the reflected light from the subject to the image sensor. Is calculated. Further, the refraction direction of the light beam for each imaging lens is calculated from the calculated reflection direction of the light beam and the propagation path of the light beam, and the propagation path of the principal ray is calculated to calculate the image formation position on the image sensor. Then, the change of the reading position on the subject is calculated from the calculated image forming position, and the reading position is calculated by calculation from the position and inclination of the optical member at an arbitrary moment, and the reading position due to the inclination and vibration of the optical member is calculated. Correct the misalignment. Therefore, the image fluctuation can be corrected, the reading position shift due to the inclination or vibration of the optical member can be corrected, the time for the initial adjustment of the optical member can be reduced in the manufacturing stage, and the read image can be read with time in use. Can be corrected.
[0118]
Further, according to the image position correcting method in the image reading device as another invention, the scanning displacement of at least one reflecting member is measured at at least two points, the measured data is stored, and the reflection is measured from the measured displacement. Find the position and inclination of the member. Then, the light beam propagating in the opposite direction to the calculated light beam reflection direction is calculated, the starting point of the light beam on the subject not affected by the reflection member is obtained, and the propagation of the principal ray from the emission point is calculated. By calculating the path, an image formation position on the image sensor is calculated. Further, a change in the reading position on the subject is calculated from the calculated image forming position, and a deviation of the reading position due to the inclination or vibration of the optical member is corrected. Therefore, it is possible to shorten the time required for the initial adjustment of the optical member in the manufacturing stage, and to correct the deterioration of the read image with time during use.
[0119]
Another aspect of the present invention is characterized in a program for causing a computer to execute the image position correcting method in the image reading device. Therefore, an image position correction method capable of correcting image fluctuation and correcting a shift of a reading position due to inclination or vibration of an optical member can be generally applied to an image reading apparatus.
[0120]
Another aspect of the present invention is characterized in a computer-readable recording medium storing a program for executing the image position correcting method. Therefore, an image reading apparatus to which the image position correction method is applied can be universally constructed without changing an existing system.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the configuration of an image reading apparatus according to the present invention.
FIG. 2 is a schematic sectional view showing a configuration of the image reading apparatus of FIG.
FIG. 3 is a perspective view showing a configuration example of a displacement measuring device provided in the image reading device of the present invention.
FIG. 4 is a block diagram showing a configuration of an image position correction circuit to which an image position correction method according to another embodiment of the present invention is applied.
FIG. 5 is a flowchart illustrating an operation of the image position correction device of the present embodiment.
FIG. 6 is a diagram illustrating a concept of coordinate conversion of a reflection mirror.
FIG. 7 is a diagram showing a state of an emitted light beam and reflection.
FIG. 8 is a diagram showing an emitted light beam and a state of reflection.
FIG. 9 is a diagram illustrating an example of calculation of the position and direction of the reflected light flux vector Q ″.
FIG. 10 is a diagram showing a procedure for calculating an imaging position by refraction of a lens.
FIG. 11 is a diagram illustrating a change in a reading position in a main scanning direction and a sub-scanning direction.
FIG. 12 is a perspective view showing the configuration of a reading position evaluation device to which the image position correction device of the present embodiment is applied.
FIG. 13 is a diagram illustrating another image position correction.
FIG. 14 is a diagram illustrating another image position correction method.
FIG. 15 is a block diagram showing the configuration of a specific device for activating a program for executing each embodiment of the image position correction method of the present invention.
[Explanation of symbols]
10, 41; image reading device, 11; document setting place, 12, 15;
13; one-dimensional imaging element; 14; lens; 16; image signal output port;
17; driving means, 18; contact glass, 19; original, 20; lamp,
21; imaging area; 31 to 33; reflection mirror; 34; reflection jig;
35, 37; non-contact displacement meter, 38; slide rail, 42; data bus,
43: image calculation unit, 44: displacement measurement device, 45; control unit,
46; arithmetic processing unit, 61; origin plane, 62; origin, 63 to 65; reflection surface,
66; imaging lens, 67; imaging surface, 71; reflection surface, 72; lens surface,
73; lens; 74; imaging surface; 81; original surface;
85; imaging plane; 86; imaging lens; 87; chief ray.

Claims (7)

An illuminating means having an optical system member for reflecting and condensing light emitted from a light source for illuminating an arbitrary subject, and a first traveling body which scans and moves the illuminating means relative to the subject An imaging element for one-dimensionally capturing the reflected light from the subject; a reflecting member for guiding the reflected light from the subject to the imaging element; Image reading means for reading an image of the subject by scanning the first traveling body to form an image of the subject on the image pickup device; and A signal processing unit for generating an image signal from a signal output from the reading unit;
An image reading apparatus comprising: a plurality of displacement measuring means for measuring a scanning displacement of at least one of the reflection members at at least two points. It stores data measured by the displacement measuring means, and has an arithmetic processing unit for calculating the position and inclination of the reflecting member from the measured speed, and by the arithmetic processing unit, the position of the optical member at any moment and The image reading apparatus according to claim 1, wherein a reading position is calculated from the inclination, and a deviation of the reading position due to the inclination or vibration of the optical member is corrected. The position and inclination of the reflection member are obtained from the displacement measured by the arithmetic processing unit, the refraction direction of the light beam for each imaging lens is calculated from the calculated reflection direction of the light beam and the propagation path of the light beam, and the propagation of the principal ray 2. The image forming apparatus according to claim 1, wherein a path is calculated to calculate an image forming position on the image sensor, a change in a reading position on the subject is calculated from the calculated image forming position, and a shift of the reading position is corrected. Image reading device. The scanning displacement of at least one traveling body is measured at at least two points, measurement data is stored, the position and inclination of the traveling body constituting the optical system are calculated from the measured scanning displacement, and the calculated position of the traveling body is calculated. From the inclination and the inclination, the inclination of the reflection member installed on the traveling body was calculated by calculation, and the reflection direction of the light beam and the propagation path of the light beam due to the inclination of the reflection member for guiding the reflected light from the subject to the image sensor were calculated and calculated. From the reflection direction of the light beam and the propagation path of the light beam, calculate the refraction direction of the light beam for each imaging lens, calculate the propagation path of the chief ray, calculate the imaging position on the image sensor, and from the calculated imaging position It is characterized by calculating the change of the reading position on the subject, calculating the reading position by calculation from the position and inclination of the optical member at any moment, and correcting the deviation of the reading position due to the inclination and vibration of the optical member. Image reading equipment Image position correction method in the. The scanning displacement of at least one reflecting member is measured at at least two points, the measured data is stored, the position and the inclination of the reflecting member are obtained from the measured displacement, and the calculated direction is reversed with respect to the calculated light beam reflection direction. The light beam propagating in the direction is calculated, the starting point of the light beam on the subject not affected by the reflection member is obtained, and the propagation path of the principal ray from the emission point is calculated, thereby forming the light beam on the image sensor. Image position correction in an image reading apparatus, wherein an image position is calculated, a change in a reading position on a subject is calculated from the calculated image forming position, and a deviation of the reading position due to inclination or vibration of an optical member is corrected. Method. A program for causing a computer to execute the image position correcting method in the image reading device according to claim 4. A computer-readable recording medium storing a program for executing the image position correcting method in the image reading device according to claim 4.

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