JP2005031205A - Angle detector and projector equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angle detector which automatically and exactly detects the relative angle of inclination with a screen of a projector for the purpose of correcting the trapezoidal distortion of an image on the screen at a high speed. <P>SOLUTION: The angle detector has a passive type line system range finder (3) equipped with a pair of lenses (31a and 31b) spaced apart a base length, line sensors (31c and 31d) parted from the pair of the lenses, and an operation part (32) for operating the distances up to a plurality of different positions lined up rectilinearly on a flat measuring object based on the outputs from the line sensors, and a means (55) for adjusting the number of measurement times which decreases measurement errors by increasing the number of measurement times more than the case the distances operated by the operation section are equal to or below a first set value when the distances are greater than the first set value and which decreases the measurement errors by increasing the number of measurement times of inclination angle more than the case the inclination angle operated by the operation section is equal to or below a second set value when the inclination angle is greater than the second set value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

ここで、Ｌ（ ）：基準部側センサデータ
Ｓａ ：基準側スタートアドレス
Ｗｎ ：演算ウインドウ数
ｔ ：整数（一般的には１〜４）
ノイズの影響を除去するには、差分の絶対値が所定値（ノイズキャンセルレベル）以下の場合は、総和に加えない。
【００７３】
次ぎに図１３を参照して、別の参考方法によるパッシブ型ライン式測距装置３を用いて傾斜角度θ１の計算方法を説明する。図１３に示すように、パッシブ型ライン式測距装置３の基線長ｋ方向（プロジェクタ２の水平方向）に対するスクリーン１の傾斜角度をθ１とし、図５で説明した方法により、ラインセンサ３１ｃの測距演算領域３１ｃ７の測距方向に沿って測距演算して算出されたスクリーン１までの距離がＬ１、測距演算領域３１ｃ３の測距方向に沿って測距演算して算出されたスクリーン１までの距離がＬ２とする。予め知られている測距演算領域３１ｃ３の測距方向と基線長方向に垂直な方向とがなす角度をβとし、同じく予め知られている測距演算領域３１ｃ７の測距方向と基線長方向に垂直な方向とがなす角度をγとする。傾斜角度θ１は、次式で計算される。
【００７４】
θ１＝ａｒｃｔａｎ（Ｌ２ｃｏｓβ−Ｌ１ｃｏｓγ）／（Ｌ１ｓｉｎγ＋Ｌ２ｓｉｎβ）
【００７５】
次ぎに、図１４を参照して説明する。本実施の形態によるパッシブ型ライン式測距装置３により距離が測定される測距方向は、ラインセンサ３１ｃが例えば１６２画素列を有する場合は図６に示すように例えば１１であるが、この図１４では簡潔にするため７つの測距方向のみを例示的に示す。図１４には７つの測距方向にある測定対象のスクリーン１上の７つの位置１Ａ、１Ｂ、１Ｃ、１Ｄ、１Ｅ、１Ｆ、１Ｇから基線長ｋを延長した直線に下ろした垂線の長さが距離として測定される。このように、本発明では、測距結果は、基線長ｋ方向（水平方向）に沿ったスクリーン１平面上の例えば７つの測定位置１Ａ、１Ｂ、１Ｃ、１Ｄ、１Ｅ、１Ｆ及び１Ｇからそれぞれ、基線長ｋを延長した直線上に下ろした垂線の長さである（例えば、図５のＬＲ’又は図８のＬＬ’、ＬＲ’に対応する長さ）。このパッシブ型ライン式測距装置３により測定された測距結果に基づいて、プロジェクタ２は、スクリーン１が水平（基線長ｋ）方向においてプロジェクタ２の主面に対してなす、スクリーン１の傾斜角度θ１を図８を参照して前述した方法で算出する。
【００７６】
しかしながら、パッシブ型ライン式測距装置３により、複数の測定位置から基線長ｋを延長した直線上に下ろした垂線の長さ（例えば、図５のＬＲ’又は図８のＬＬ’、ＬＲ’の距離）を測定すると、測距結果は、図３の信頼性判定部３２ｉによる信頼性判定や図３の平均化部３２ｊ等の手段により正確な測定値が得られるように補正しても、なお、図１５（ａ）に示すように、コントラスト重心位置を横軸、測定された距離（測距結果）を縦軸に取って示した丸点の位置にある距離として測定される。なお、図１５（ａ）では説明を簡潔にするために、４つの測定位置１Ｄ、１Ｅ、１Ｆ、１Ｇの測定結果のみを示す。
【００７７】
測距結果が、スクリーン１平面上の複数の測定位置から基線長ｋ方向に延長した直線上に下ろした垂線の長さである場合（図５のＬＲ’又は図８のＬＬ’、ＬＲ’の場合）、本来ならば直線的に変化するはずである。しかし、現実の測距結果は、図１５（ａ）の４つの丸点の測定結果、１Ｄ、１Ｅ、１Ｆ、１Ｇに示すように直線的に変化しない。このような直線関係からの逸脱は、製造誤差や測定時のノイズ等に起因する。
【００７８】
図８又は図１３で説明した傾斜角度θ１を求める方法を使用する場合、傾斜角度θ１を計算するために必要な２つの測定位置を図１５（ａ）の４つの丸点１Ｄ、１Ｅ、１Ｆ、１Ｇに示した測定値を使用する。例えば、１Ｇを基準点１としてその隣りの測定点１Ｆを用いると傾斜角度θ１’が得られ、１Ｆを基準点２としてその隣りの測定点１Ｅを用いると傾斜角度θ１”が得られ、そして１Ｅを基準点３としてその隣りの点１Ｄを用いると傾斜角度θ１”’が得られる。基準点ともう１つの測定点の選び方に依存して図８又は図１３て説明した傾斜角度の求め方では得られる傾斜角度が異なる可能性がある。このように異なる傾斜角度θ１’、θ１”、及びθ１”’から、スクリーン１の傾斜角度θ１を求めるためには、さらに、異なる傾斜角度θ１’、θ１”、及びθ１”’から最大値と最小値を除いた中間値又はその平均値を求める等の、さらなる処理を行なわなければならない。このように、複数の測距結果からスクリーン１の正確な傾斜角度θ１を一義的に算出することが困難である。
【００７９】
従って、傾斜角度θ１を正確に求める方法として、平面的な測定対象上に直線的に並んだ複数の測定位置の測定値の間には、一定の相関関係（分布）、すなわち、直線的に並ぶという相関関係（分布）があることに基づき、この複数の測定値の相関関係（分布）を表わす直線を近似して求め、近似により求められた直線の傾きからスクリーン傾斜角度θ１を求める。
【００８０】
図１５（ｂ）に示すように、本発明では、スクリーン１平面上の直線的に並んだ複数の測定位置の測距結果の間の相関関係、すなわち、分布を表わす直線ｙ＝ａｘ＋ｂを近似により求める。ここで、ｘは基線長ｋを延長した直線上の座標位置を表し（すなわち、図１５（ｂ）の横軸）、ｙは基線長ｋからスクリーン１上の位置までの距離を表わし（すなわち、図１５（ｂ）の縦軸）、ａはこの直線ｙの傾きを表わす。この直線ｙの傾きａが求めるスクリーン１の傾斜角度θ１となる。すなわち、ａ＝θ１である。この直線ｙを、複数の測定位置の測定結果の分布、すなわち、相関関係から近似により求めるため、最小二乗法を使用する。
図１５（ｂ）に示すように、本実施の形態で使用する最小二乗法は、図１５（ａ）中の丸点の１Ｇ、１Ｆ、…、等に対応した各測定位置の測定結果を表わす点をＰ１、Ｐ２、…、Ｐｎとし、各点Ｐ１、Ｐ２、…、Ｐｎから基線長ｋを延長した直線に対応した図１５（ｂ）の横軸へ垂直方向に下ろした線と直線ｙ＝ａｘ−ｂとの交点をＱ１、Ｑ２、…、Ｑｎとした場合、各線分Ｐ１Ｑ１、Ｐ２Ｑ２、…、ＰｎＱｎの長さの二乗の総和Σが最小になるように、直線ｙ＝ａｘ＋ｂの傾きａとｂの値を求めるものである。
【００８１】
最小二乗法により、複数の測定結果の相関関係（分布）を表わす直線ｙ＝ａｘ＋ｂの傾きａを求める方法は周知である。
【００８２】
例えば、図１５（ｂ）上で複数ｎ個の測定位置の測定結果を表わす点Ｐ１、Ｐ２、…、Ｐｎのｘ、ｙ座標値をそれぞれ（ｘ１、ｙ１）、（ｘ２、ｙ２）、…、（ｘｎ、ｙｎ）とする。
これら複数ｎ個の測定結果の点Ｐ１、Ｐ２、…、Ｐｎのｘ座標値の平均値をｘｍ＝（ｘ１＋ｘ２＋…＋ｘｎ）／ｎとし、ｙ座標値の平均値をｙｍ＝（ｙ１＋ｙ２＋…＋ｙｎ）／ｎとする。
これら複数ｎ個の測定結果の点Ｐ１、Ｐ２、…、Ｐｎのｘ座標値の分散はδ^２ｘ＝［（ｘ１−ｘｍ）^２＋（ｘ２−ｘｍ）^２＋…＋（ｘｎ−ｘｍ）^２］／ｎとなり、ｙ座標値の分散はδ^２ｙ＝［（ｙ１−ｙｍ）^２＋（ｙ２−ｙｍ）^２＋…＋（ｙｎ−ｙｍ）^２］／ｎとなり、共分散はδｘｙ＝［（ｘ１−ｘｍ）（ｙ１−ｙｍ）＋（ｘ２−ｘｍ）（ｙ１−ｙｍ）＋…＋（ｘｎ−ｘｍ）（ｙｎ−ｙｍ）］／ｎとなる。
相関係数はρｘｙ＝δｘｙ／δｘδｙとなる。
最小二乗法によると、複数ｎ個の測定結果の相関関係（分布）を表わす直線ｙ＝ａｘ＋ｂの傾きａは、ａ＝δｙρｘｙ／δｘの関係から求められる。一方、ｂは、ｂ＝ｙｍ−ｘｍδｙρｘｙ／δｘの関係から求められる。
スクリーン１の傾斜角度θ１は、傾きａから、θ１＝ｔａｎ^−１ａの関係から求められる。
【００８３】
複数ｎ個の測定値は本来はほぼ直線的に変化する関係にあり、この直線的変化から１つの傾斜角度θ１が一義的に算出されるべきである。しかし、実際は、ノイズ及び製造誤差等のさまざまな原因により、測定された距離を結んでも直線的に並ばず、図１５（ａ）のように折れ線グラフのように並ぶ。この問題を解決するには、測定対象の平面的物体上に直線的に並んだ複数の位置までの距離を測定すると、それらの測距結果が直線的に分布するという相関関係を用いて、個々の位置の距離測定による誤差が最小となる直線ｙ＝ａｘ＋ｂを最小二乗法を用いて算出して、その直線ｙの傾きａをスクリーン１の傾斜角度として使用する。
【００８４】
図１６に、図６に示されたパッシブ型ライン式測距装置３のラインセンサ３１ｃ内の距離を測定するために使用される測距演算領域３１ｃ１乃至３１ｃ１１を、模式的に示す。本実施の形態のラインセンサ３１ｃ内の各演算領域３１ｃ１乃至３１ｃ１１は、隣りの演算領域と互いにほぼ半分の画素数を共有する関係になっている。例えば、領域３１ｃ１と領域３１ｃ２はほぼ半分の画素数を互いに共有し、領域３１ｃ２と領域３１ｃ３は互いにほぼ半分の画素数を共有している。図１６は、このような本実施の形態で使用される図６のラインセンサ３１ｃ内の測距演算領域３１ｃ１乃至３１ｃ１１間の画素の重複関係を上下に示した模式図で示す。
【００８５】
図１６に示すような測距演算領域３１ｃ１乃至３１ｃ１１を有するラインセンサ３１ｃにより、スクリーン１のような平面上の直線的に並んだ複数の位置を測距する場合、領域３１ｃ１により測定された距離、領域３１ｃ２により測定された距離、及び領域３１ｃ３により測定された距離の３者の関係は、領域３１ｃ１と領域３１ｃ３により測定された距離の平均値が、領域３１ｃ２により測定された距離に等しくなる。何故ならば、測定対象は平面的物体であるため、その上に直線的に並んだ位置までの測距結果は直線的関係を有するからである。すなわち、測距結果同士は相関関係を有する。この相関関係は測定対象が平面的物体であることから起因する。
【００８６】
一般的に、このようなラインセンサのＮ番目の測距演算領域とＮ＋１番目の測距演算領域とＮ＋２番目の測距演算領域でもって、スクリーン１のような平面物体上のある直線に沿った複数の位置を距離を測定した場合、Ｎ番目の領域による測定距離とＮ＋２番目の領域による測定距離の平均値Ｓは、その中間のＮ＋１番目の領域による測定距離Ｔとほぼ等しくなるはずである。本発明は、上記原理を用いて、複数の測距演算領域の測距結果から、中間の測距演算領域の測距結果Ｔが両隣の測距演算領域の平均値Ｓと所定の判定値以上離間している場合（｜Ｔ−Ｓ｜≧判定値、若しくは、｜Ｔ／Ｓ−１｜≧判定値）は、これらの測距演算領域の測距結果は信頼性が無いと判定して、以後の演算処理から排除する。なお、判定値の大きさは目的に応じて適宜選択できる。
【００８７】
さらに、このようなラインセンサのＮ番目の測距演算領域とＮ＋１番目の測距演算領域とＮ＋２番目の測距演算領域でもって、スクリーン１のような平面物体上のある直線に沿って互いに隣接した位置の距離を測定した場合の測定結果は、平均した方が個々の測定演算領域（エリア）の製造誤差や測定時の雑音の影響を少なくすることができる。すなわち、
（１）個々の領域のコントラスト重心位置に対しての平均化処理で、Ｎ、Ｎ＋１、及びＮ＋２の領域に対してのコントラスト分布の重心位置の平均を検出する。
（２）個々の領域の測距結果に対しての平均化処理により、Ｎ、Ｎ＋１、及びＮ＋２領域に対しての測距結果の平均を検出する。
【００８８】
上記２つの平均化処理（１）及び（２）を、図１７（ａ）の測定結果の小グループＮ、Ｎ＋１、Ｎ＋２（Ｎ＝１〜４の自然数）についておこなう。図１７（ａ）で測定結果の小グループはそれぞれが３つの測距演算領域を含む４つの小グループとしているが、この小グループ内に含まれる互いに隣接した測距演算領域の数、及び小グループの数は、自由に選ぶことができる。
【００８９】
図１７（ｂ）は、各小グループ（Ｎ＝１〜４）毎の測距結果の平均値を縦軸に、各小グループ毎のコントラスト分布の重心の平均位置を横軸に示したグラフである。図１７（ａ）と図１７（ｂ）を比較してみれば、容易に理解されるように、３つの互い測距演算領域の平均化された値によるグラフはほぼ直線上に並ぶ。従って、スクリーン１の傾斜角度θ１を、図１７（ｂ）の平均化された値から上述したように最小二乗法を用いて算出すれば、より精度の高い角度を検出できる。
【００９０】
なお、プロジェクタ２の投射光学系が自動焦点機構を有していて、スクリーン１までの距離を自動的に検出して、スクリーン１上に投射された画像の自動焦点を行なう場合、スクリーン１までの距離としては、図１７（ｂ）に示される測距結果の平均値のうち、最大値と最小値を除いた中央値又はそれらの平均値を選ぶことができる。代替的に、ラインセンサ３１ｃの中央の測距演算領域３１ｃ６の測距結果が両隣りの測距演算領域の測距結果と直線関係を有する場合には、それを使用してもよい。このようにして、より精度の高い距離を検出して、正確な自動焦点合わせができる。
【００９１】
次ぎに、図１８及び図１９を参照して、本発明の角度検出装置の動作を説明する。
【００９２】
まず、図１８を図１と併せて参照しながら説明する。プロジェクタ２に電源が投入されるか、又はプロジェクタ２の動作中において定期的な角度検出動作が開始されると、制御回路５は外部の図示しないパーソナルコンピュータ等から入力画像データが入力されているかどうかを判断して、外部からの入力画像データがあれば、投影画像生成部６にその画像データに応じた表示データを出力させて、表示駆動部７及び投射光学系を介して画像をスクリーン１に投射する。もし、入力画像データがなければ、制御回路５はプロジェクタ２内に予め記憶された調整用コントラスト画像データ（例えば、ロゴマーク等を含んだ適当な画像データ）を投影画像生成部６に出力し、表示駆動部７及び投射光学系を介してその画像をスクリーン１に投射して角度検出操作をスタートする（図１８、ブロック１０１）。
【００９３】
上記の動作は、プロジェクタ２が持つ本来の画像投影機能により投射された画像を使用して角度を検出をするための動作であり、このようにパッシブ型ライン式測距装置３及び４は調整用コントラスト画像の投影専用の投光部が不要である。
【００９４】
続いて、制御回路５は、ＥＥＰＲＯＭ（メモリ部１０）中に傾斜角度の測定回数ｊを初回値（「１」）に設定し（ブロック１０２）、距離の測定回数ｉの初回値（「１」）を設定し（ブロック１０３）、パッシブ型ライン式測距装置３及び４の撮像部３１及び４１の距離測定機能と角度検出機能を動作させる前に自動焦点調節集積回路を制御して（ブロック１０４）、スクリーン１上の水平面内及び垂直面内にある複数の位置までの距離を測定して、水平面内及び垂直面内のスクリーン１のプロジェクタ２に対する傾斜角度を検出し易いようにスクリーン１上の画像を合焦する。なお、上述の通り角度検出操作スタート（ブロック１０１）は、プロジェクタ２の電源投入時に限らず、プロジェクタ２の動作中に随時に行なうことができる。この際には、スクリーン１上に投射されている任意の画像が角度検出のための測距に使用される。
【００９５】
次に、図１８に図３を合せて参照して測距動作および傾斜角度検出動作を説明すると、撮像部３１及び４１を動作させて、ラインセンサからデータを読出してＡ／Ｄ変換（図３中の３２ａ）をする（ブロック１０５）。ラインセンサの各測距演算領域（エリア）３１ｃＮ（Ｎ＝１、…、１１）のコントラスト重心がコントラスト重心演算部（図３の３２ｈ）で算出されて、各測距演算領域（エリア）３１ｃＮ（Ｎ＝１、…、１１）のコントラスト重心の平均値が平均化部（図３の３２ｊ）で求められてＲＡＭ（メモリ手段１０）に記憶される（ブロック１０６）。ラインセンサのセンサデータから直流成分を除去するためのフィルタ（図３中の３２ｃ）処理がされ（ブロック１０７）、その後に、各測距演算領域３１ｃ１乃至３１ｃ１１に関して、相関演算（図３中の３２ｄ、３２ｅ）、補間演算（図３中の３２ｆ）、位相差検出演算（図３中の３２ｇ）されて、測距演算がされる（ブロック１０８）。そして信頼性判定（図３中の通常の信頼性判定部３２ｉにより、最大相関検出部３２ｅにおいて得られる一致度が所定値以上かどうかの判定）を行い、この信頼性判定が合格すれば、ＣＯＮＦ＿ＦＬＧ１＝ＯＫをセットする（１０９）。もし、２つ以上の測距演算領域（エリア）でデータ信頼性判定（ＣＯＮＦ＿ＦＬＧ１＝ＯＫ）に合格していなければ、角度検出は不可能であるから、ブロック１１０において、出口Ｃを経て図１９の入口Ｃに行き、図１９で角度検出不能であると判定されて（ブロック１２３）、終了する（ブロック１２４）。
【００９６】
もし、図１８のブロック１１０において２つ以上の測距演算領域でデータ信頼性に合格していれば、測距結果と重心データをＲＡＭ（メモリ部１０）に記憶する（ブロック１１１）。そして、各測距演算領域（エリア）３１ｃＮ（Ｎ＝１、…、１１）の算出された測距結果をＲＡＭ（メモリ部１０）に記憶して、複数の測定回数ｉによる平均値（四捨五入で単位ｍｍで）を平均化部（図３の３２ｊ）で求める（ブロック１１１）。そして、図３中の測定回数調整手段５５が、初回（ｉ＝１）の測定により測定された距離が所定の第１の設定値、例えば、１０ｍ、よりも大きいかどうかを判定する（ブロック１１２）。もし、測定された距離が所定の第１の設定値（１０ｍ）よりも大きければ、距離測定回数ｉとしてＥＥＰＲＯＭ（メモリ部１０）に予め記憶された所定回数のＤＡＴＡ１（例えば、「５」）を使用して、距離測定回数ｉが所定回数（ＤＡＴＡ１＝５）に達するまでブロック１０３に戻る（ブロック１１３）。もし、測定された距離が所定の第１の設定値（１０ｍ）以下であれば、距離測定回数ｉとしてＥＥＰＲＯＭ（メモリ部１０）に予め記憶されたＤＡＴＡ１よりも少ない所定回数のＤＡＴＡ２（例えば、「３」）を使用して、距離測定回数ｉが所定回数（ＤＡＴＡ２＝３）に達するまでブロック１０３に戻る（ブロック１１４）。このようにして、各測距演算領域３１ｃＮ（Ｎ＝１、…、１１）毎に距離及びコントラスト重心位置の測定結果が、測距結果の距離の大きさが第１の設定値（１０ｍ）よりも大きい又は以下に応じて測定回数ｉ（例えば、ＤＡＴＡ１＝５又はＤＡＴＡ２＝３）により得られた測距結果の平均値が平均化部（図３の３２ｊ）により求められて、ＲＡＭ（メモリ部１０）に記憶されていく。なお、ブロック１１１で測定回数ｉによる測距結果の平均値を求めるに代えて、測距結果の最大値と最小値を除いた中央値若しくは最大値と最小値を除いた平均値を求めてもよい。そして、ＥＥＰＲＯＭ（メモリ部１０）に記憶された測定回数ｉ（例えば、ＤＡＴＡ１＝５又はＤＡＴＡ２＝３）に到達するまで繰り返される。測定回数ｉに達すると、出口Ａから図１９の入口Ａに操作が移る。
【００９７】
次に、図１９を参照して説明する。平均化部（図３の３２ｊ）により、測距結果の大きさが第１の設定値（例えば、１０ｍ）よりも大きいか又は以下に応じて選ばれた測定回数ｉ（ＤＡＴＡ１＝５又はＤＡＴＡ２＝３）で平均化された、各測距演算領域３１ｃＮ（Ｎ＝１、…、１１）の距離測定値とコントラスト重心測定値の相互信頼性（前後の測距演算領域の測定結果と大きく矛盾していないかの妥当性）の判定処理（ブロック１１５とブロック１１６）を行なう。もし、測距結果の相互信頼性の判定処理で不合格とされた場合は角度検出不能と判断されて（ブロック１２３）、終了する（ブロック１２４）。もし、測距結果の相互信頼性と判定処理に合格すると、平滑化（測定対象がスクリーン平面であるため前後の測距演算領域の測定結果と平均化してバラツキを少なくする）の処理を行なう（ブロック１１７）。
【００９８】
さらに、前述したように最小二乗法により角度演算が行なわれて、スクリーンのプロジェクタに対する相対的な傾斜角度が求められる（ブロック１１８）。そして、求められた傾斜角度がＲＡＭ（メモリ部１０）に記憶されて、傾斜角度の測定回数ｊにより傾斜角度の平均値が求められる（ブロック１１９）。そして、図３中の測定回数調整手段５５が、初回（ｊ＝１）の測定により得られた傾斜角度が所定の第１の設定値、例えば、１５度、よりも大きいかどうかを判定する（ブロック１２０）。もし、傾斜角度が所定の第２の設定値よりも大きければ、傾斜角度の測定回数ｊがＥＥＰＲＯＭ（メモリ部１０）に予め記憶されたＤＡＴＡ３（例えば、「５」）の所定回数に設定される（ブロック１２１）。もし、傾斜角度が所定の第２の設定値以下であれば、傾斜角度の測定回数ｊがＥＥＰＲＯＭ（メモリ部１０）に予め記憶されたＤＡＴＡ３よりも小さいＤＡＴＡ４（例えば、「３」）の所定回数に設定される（ブロック１２２）。このようにして、初回（ｊ＝１）の測定により得られた傾斜角度が第２の設定値（例えば、１５度）より大きか又は以下に応じて決まる測定回数ｊ（例えば、ＤＡＴＡ３＝５又はＤＡＴＡ４＝３）に達するまで、出口Ｂを経て図１８の入口Ｂを通じてブロック１０２に戻り、距離の測定と傾斜角度の算出が繰り返される。所定の傾斜角度の測定回数ｊ（例えば、ＤＡＴＡ３＝５又はＤＡＴＡ４＝３）に達したならば、角度検出動作が終了する（ブロック１２４）。なお、ブロック１１９で複数の測定回数ｊによる傾斜角度の平均値を求めるに代えて、求められた傾斜角度の最大値と最小値を除いた中央値若しくは最大値と最小値を除いた平均値を求めてもよい。
【００９９】
以上説明した通り、本発明の角度検出装置は、最初の測距結果が第１の設定値よりも大きい場合は、第１の設定値以下の場合と較べて測定回数を増やして測距結果の平均値又は最大値と最小値を除いた中央値若しくは最大値と最小値を除いた平均値を求めることにより、測距結果の測定誤差を小さくするようにしている。そして、測距結果が第１の設定値以下の場合は、相対的に測定誤差も小さいから測定回数を比較的少なくして、高速な測距操作を行なうようにしている。三角測距法に基づく測距結果は、遠距離ほど測定誤差が大きくなるため、測定回数を増やして平均化することにより、測定誤差の影響をできるだけ小さくして、精度の高い測距結果が得られるようにし、一方、近距離では測定誤差は相対的に小さいため、測定回数を少なくして測距操作の高速化を図っている。
【０１００】
本発明の角度検出装置はさらに、最初の測距結果から求められた傾斜角度が第２の設定値よりも大きい場合は、第２の設定値以下の場合と較べて距離の測定回数と傾斜角度の測定算出回数を増やして、求められた傾斜角度の平均値又は最大値と最小値を除いた中央値若しくは最大値と最小値を除いた平均値を求めることにより、傾斜角度の測定誤差を小さくするようにしている。そして、傾斜角度が第２の設定値以下の場合は、相対的に傾斜角度の測定誤差も小さいから測定回数を比較的少なくして、高速な傾斜角度の検出を行なうようにしている。これは、スクリーンの傾斜角度が大きいとスクリーン上の画像の合焦調節ができずぼやけるため、測定回数を増やして測定誤差の影響をできるだけ小さくして、精度の高い角度検出が得られるようにし、一方、近距離では測定誤差は相対的に小さいため、測定回数を少なくして角度検出の高速化を図っている。
【０１０１】
以上説明した本発明の角度検出装置をプロジェクタに使用すれば、測距結果が大きい場合は測定誤差も相対的に大きいから測距回数を増やすことにより測距結果の精度を高め、又、求められた傾斜角度が大きい場合はスクリーンに投影された画像の合焦のずれによる画像のぼけによる測定誤差が大きいから測距回数を増やして得られる測距結果の精度を高めてそれに基づいて求められる傾斜角度の精度を高めている。この結果、スクリーンに投影さたれ画像の台形歪みの補正を正確に高速に行なうことができる。なお、上述した本実施の形態においては、水平方向と垂直方向の一対のライン式測距装置を使用したが、直交する関係に配置する必要は無く、また、１つのライン式測距装置のみでもよい。また、測定対象としてスクリーン平面を用いたが、スクリーンに限らず、どんな平面的物体の測定対象についても本発明の角度検出装置は適用できる。例えば、測定対象の平面的物体としては、工作機械により加工される被加工物であって良く、これら被加工物に対して加工道具を正対させるため、被加工物と加工道具の相対的な傾斜角度を検出するためにも、本発明の角度検出器は適用できる。
【０１０２】
さらに、上述した本発明の実施の形態による複数の測定点の相関関係（分布）を表わす直線を近似する方法として、最小二乗化法を説明したが、最小二乗化法に限らず、その他の近似方法を使用して複数の測定点の相関関係（分布）を表わす直線を近似して、傾斜角度を求めてもよい。なお、上述した本実施の形態においては、図８又は図１３で説明した傾斜角度θ１の求め方も使用することができる。
【０１０３】
【発明の効果】
本発明の請求項１乃至３に記載された本発明によれば、正確に且つ高速に角度検出することが可能な角度検出装置を達成できる。
【０１０４】
請求項４に記載された本発明によれば、投影されるスクリーンのプロジェクタに対する傾斜角度を自動的に正確且つ高速に検出できる角度検出装置を達成できる。
【０１０５】
請求項５に記載された本発明によれば、プロジェクタとスクリーンの相対的な傾斜角度に起因する画像の台形歪みを自動的に正確且つ高速に補正することができるプロジェクタを達成できる。
【図面の簡単な説明】
【図１】本発明の１つの実施の形態による角度検出装置を有するプロジェクタの構成を示す概略ブロック図。
【図２】図１に示したプロジェクタの概略正面図。
【図３】本発明の１つの実施の形態による角度検出装置の機能ブロック図。
【図４】本発明の１つの実施の形態による角度検出装置に含まれる測距装置の測距操作を説明する図。
【図５】本発明の１つの実施の形態による角度検出装置に含まれる測距装置の測距操作を説明する別の図。
【図６】本発明の１つの実施の形態による角度検出装置に含まれる測距装置の一対のラインセンサの概略を示すブロック図。
【図７】本発明の１つの実施の形態による角度検出装置に含まれる測距装置による複数位置の距離測定を説明する別の図。
【図８】本発明の１つの実施の形態による角度検出装置に含まれる測距装置による角度検出方法を説明する図。
【図９】図８の角度検出方法を説明する別の図。
【図１０】図８の角度検出方法を説明する別の図。
【図１１】図８の角度検出方法を説明する別の図。
【図１２】本発明の１つの実施の形態による角度検出装置に含まれる測距装置の測距演算領域のコントラスト重心位置を求める方法を説明する別の図。
【図１３】本発明の１つの実施の形態による角度検出装置に含まれる測距装置による角度検出方法を説明する別の図。
【図１４】本発明の１つの実施の形態による角度検出装置に含まれる測距装置による複数位置の測距結果に基づく角度検出方法を説明する別の図。
【図１５（ａ）】角度検出装置に含まれる測距装置による複数位置の測距結果及びそれらに基づいた角度算出結果を示すグラフ。
【図１５（ｂ）】角度検出装置に含まれる測距装置による複数位置の測距結果の相互関係（分布）を表わす直線を本発明による最小二乗化方法で近似する方法説明するグラフ。
【図１６】本発明の１つの実施の形態による角度検出装置に含まれる測距装置のラインセンサの測距演算領域の構成を概略的に示す模式図。
【図１７】本発明の１つの実施の形態による測距結果の代表値とコントラスト重心の代表値とを求める方法を示す図。
【図１８】本発明の１つの実施の形態による角度検出装置の動作を示すフローチャート図。
【図１９】図１８のフローチャート図に接続する本発明の１つの実施の形態による角度検出装置の動作を示すフローチャート図。
【符号の説明】
１ スクリーン
１Ａ〜１Ｇ 測定位置
２ プロジェクタ
３ 測距装置
４ 測距装置
５ 制御回路
３１ 撮像部
３１ａ レンズ
３１ｂ レンズ
３１ｃ ラインセンサ
３１ｄ ラインセンサ
３１ｃ１〜３１ｃ１１ 測距演算領域
３２ 演算部
５１ 相互信頼性判定部
５２ 平均値演算部
５３ 角度演算部
５５ 測定回数調整手段
ｋ 基線長
θ１ 水平面内でスクリーン１が基線長ｋ方向となす傾斜角度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an angle detection device using a passive line-type distance measuring device and a projector including the same.
[0002]
[Prior art]
When a projector such as a liquid crystal projector is used, there is a problem that distortion called trapezoidal distortion occurs in an image projected on the screen due to the relative positional relationship between the projection optical axis of the projector and the screen plane projected by the projector. . This trapezoidal distortion is caused when the projector projects the image from the front of the screen so that the position of the projector is shifted from the center of the screen so as not to disturb the viewer. As a result of which the top of the screen is farther (or closer) from the projector than the bottom of the screen. It also occurs when the right side of the screen is farther (or closer) from the projector than the left side of the screen.
[0003]
Conventionally, in order to automatically correct this trapezoidal distortion, an inclination angle indicating how much the screen plane is inclined from a state perpendicular to the projector projection optical axis is automatically detected and detected. Depending on the tilt angle, an electrical correction method for generating and projecting an image having a trapezoidal distortion opposite to the projected image in the video circuit inside the projector, and a projection lens (condenser lens) of the projection optical system of the projector An optical correction method for adjusting the tilt is used (Patent Document 1).
[0004]
[Patent Document 1]
JP 2000-122617 A (see paragraph 0044 and FIG. 2)
[0005]
In order to automatically detect the relative inclination angle of how much the projection optical axis of the projector is inclined from the state perpendicular to the screen plane, as a conventional angle detection device, the one disclosed in Patent Document 1 is disclosed. is there. What is described in this patent document 1 is that each of the distances to the screen is measured by two active distance measuring sensors that are spaced apart from each other by a predetermined distance above and below the front surface of the projector main body 1, A simple inclination angle is obtained.
[0006]
[Problems to be solved by the invention]
However, in the conventional angle detection apparatus described in Patent Document 1, two distances are measured by an active distance measuring sensor, and the projector's projection optical axis is tilted relative to a direction perpendicular to the screen plane. Since the tilt angle is obtained, if one or both of the two distance measurements are not correctly measured due to a failure of the active distance sensor, the tilt angle cannot be detected and the trapezoidal distortion cannot be corrected. There was a problem.
[0007]
Furthermore, in general, when the distance between the screen and the projector is relatively large, or when the relative tilt angle is relatively large, the distance measurement error and the tilt angle detection error tend to be large. . In order to solve this, it is known that the measurement error and the detection error can be reduced by increasing the number of times of measurement and obtaining an average value or an average value excluding the maximum value and the minimum value. However, if the number of times of measurement is increased, it will take time for distance measurement and angle detection.
[0008]
Therefore, an object of the present invention is to provide an angle detection device using a passive distance measuring device and a device that can solve the conventional problems by detecting the tilt angle of a measurement object as accurately as possible in a relatively short time. Is to provide a projector.
[0009]
[Means for Solving the Problems]
According to the first aspect of the present invention, a pair of lenses arranged on the same plane and spaced apart by a base line length are set apart from the pair of lenses by a predetermined distance so as to extend in the base line length direction. A pair of line sensors that are arranged to form an image of an object to be measured on the pair of lenses, and output from the pair of line sensors, and the base line length and the line based on the measurement outputs A passive line-type distance measuring device including a calculation unit that calculates distances to a plurality of different positions on the measurement target in a plurality of different ranging directions on a plane including a sensor, and the calculation unit includes: An inclination angle calculation unit for calculating an inclination angle of the measurement target with respect to the same plane on a plane including the baseline length and the line sensor, using at least two calculation results of the calculated distance; Distance calculator is calculated, or the angle detection device which comprises a number of measurements adjusting means for adjusting the number of the measurement on the basis of the tilt angle the tilt angle calculation unit has calculated is provided.
[0010]
According to this configuration of the present invention, the distance to a plurality of positions linearly arranged on the measurement object is measured by the passive line-type distance measuring device, and the relative measurement object is based on at least two measured distances. A typical inclination angle is calculated, and the number of output measurements from the line sensor is adjusted based on the measured distance or inclination angle. Therefore, if the measurement error increases, the number of measurements can be increased, and if the measurement error is small, the number of measurements can be decreased. Therefore, the angle detection accuracy can be improved or the angle detection time can be increased according to the magnitude of the measurement error. Can be shortened.
[0011]
According to the second aspect of the present invention, the measurement number adjusting unit may be configured such that the distance calculated by the calculation unit is greater than the first set value or the tilt angle calculated by the tilt angle calculation unit. 2. The angle detection device according to claim 1, wherein when the value is larger than the second set value, the number of times of the measurement is increased as compared with the case where the value is equal to or less than the first or second set value. Provided.
[0012]
According to this configuration of the present invention, the distance to a plurality of positions linearly arranged on the measurement object is measured by the passive line-type distance measuring device, and the relative measurement object is based on at least two measured distances. A typical tilt angle is calculated. Even if some of the distance measurements to a plurality of positions on the measurement object cannot be performed correctly due to noise or a manufacturing error, it is possible to determine the tilt angle with less influence. Then, when the measured distance is larger than the first set value or when the inclination angle is larger than the second set value, the measurement number adjusting means compares the distance with the first or second set value or less. By increasing the number of output measurements from each line sensor, the distance measurement error or the tilt angle calculation error is reduced. This is because the measurement error is relatively large when the distance measurement result is larger than the first set value, and when the tilt angle is larger than the second set value, the image projected on the screen or the like is combined. Since the deviation of the focal position is large and the image is blurred, the error of the measured tilt angle is also large. For this reason, the average value of the measured distance and the calculated tilt angle is obtained by more ranging times, or the maximum value and the minimum value are removed from the more measured distance or calculated tilt angle. Thus, the measurement error can be reduced by obtaining the intermediate value or the average value. If the measured distance is less than the first set value and the calculated tilt angle is less than the second set value, the distance measurement error is relatively small and the image projected on the screen or the like is Since the error in the calculated tilt angle is small, the number of measurements is reduced by the number-of-measures adjusting means as compared with the case where the value is larger than the first or second set value. As a result, the measurement time can be shortened, accurate angle detection can be performed, and the average time required for angle detection can be shortened. The magnitudes of the first set value and the second set value, and the increase / decrease in the number of measurements can be appropriately selected according to the accuracy and speed of angle detection required for the measurement object and the angle detection device.
[0013]
According to the present invention as set forth in claim 3, a passive line-type distance measuring device for measuring the distance to a plurality of different measurement points arranged substantially linearly on the measurement object, and at least two measurements. A tilt angle calculation unit that calculates a tilt angle of the measurement target with respect to the distance measuring device based on the measured distance, and a case in which the distance exceeds a first set value or the tilt angle has a second set value. And a measurement frequency adjusting means for increasing the number of times of distance measurement by the passive line type distance measuring device when compared with the case of the first set value or the second set value or less. An angle detection device is provided.
[0014]
According to this configuration of the present invention, the distance to a plurality of positions linearly arranged on the planar object to be measured is measured by the passive line type distance measuring device, and based on at least two measured distances. The relative inclination angle of the measurement object is calculated. At this time, if the measured distance is larger than the first set value or the calculated tilt angle is larger than the second set value, the measurement number adjusting means makes the first or second set value or less. By increasing the number of times of each measurement compared to the case, the distance measurement error or the inclination angle calculation error can be reduced. When the measured distance is equal to or smaller than the first set value and when the calculated inclination angle is equal to or smaller than the second set value, the measurement error is relatively small, and therefore the first or second measurement number adjusting means is used. The number of measurements is reduced compared to the case where the value is larger than the set value. Thereby, the measurement time can be shortened, and the average time required for angle detection can be shortened. As a result, an angle detection device that performs angle detection with high accuracy in a relatively short time can be achieved.
[0015]
According to the fourth aspect of the present invention, there is provided the angle detection device according to any one of the first to third aspects, wherein the measurement object is a screen on which an image is projected.
[0016]
According to this configuration of the present invention, it is possible to provide an angle detection device that detects a relative inclination angle of a screen by using a screen on which an image is projected as a measurement target.
[0017]
According to the fifth aspect of the present invention, there is provided a projector for projecting an image onto a screen, wherein the angle detection device according to the fourth aspect and the screen on the screen based on the inclination angle calculated by the angle detection device. An image distortion correction unit that corrects the image distortion is provided.
[0018]
According to this configuration of the present invention, the trapezoidal distortion of the image caused by the relative tilt angle between the projector and the screen can be automatically corrected in a relatively short time by detecting the tilt angle. Furthermore, it is possible to control the focusing of the image on the screen based on the distance measurement result between the projector and the screen.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0020]
FIG. 1 is a schematic block diagram of a projector 2 that includes an angle detection device according to the present embodiment and electrically corrects trapezoidal distortion of an image projected on the screen 1 based on the detected tilt angle of the screen 1. The angle detection device according to the present embodiment detects a tilt angle of the projector 2 with respect to the screen 1 in a horizontal plane and a vertical plane, and therefore, a plurality of positions arranged in the horizontal and vertical directions on the plane of the screen 1 from the projector 2. A first passive line-type distance measuring device 3 and a second passive line-type distance measuring device 4 that measure the distance to each other. The passive distance measuring devices 3 and 4 receive the image projected on the screen 1 from the image projection means of the projector and measure the distance without emitting or transmitting the passive distance measuring devices 3 and 4 themselves. The line-type distance measuring device has a line sensor in which a plurality of photodetector cells are arranged in a straight line.
[0021]
FIG. 2 is a plan view showing the front of the projector 2 shown in FIG. Note that the angle detection device according to the present embodiment is not limited to the one provided in the projector, and is not limited to the one that detects the angle of inclination with the screen. It can be applied to relative tilt angle detection. The projector 2 is an example of an application in which the angle detection device of the present invention is used.
[0022]
As shown in FIG. 2, the first passive line-type distance measuring device 3 of FIG. 1 is separated by a first base line length k (FIG. 4) extending in the horizontal direction on the plane constituting the front of the projector 2. And an imaging unit 31 having a pair of lenses 31a and 31b. Similarly, the second passive line-type distance measuring device 4 extends in the vertical direction perpendicular to the horizontal direction of the imaging unit 31 on the same plane that constitutes the front surface of the projector 2 and has a second baseline length k ′ (not shown). ) Includes an imaging unit 41 including a pair of lenses 41a and 41b that are spaced apart from each other. As shown in FIG. 2, a projection lens (which may include a condenser lens or the like) 8 of a projection optical system is further provided on the same plane constituting the front of the projector 2, and an image is displayed on the screen 1. Irradiate the light to be projected. The optical axis of the projection lens 8 is perpendicular to the plane that forms the front of the projector 2.
[0023]
Please refer to FIG. 1 again. If the optical axis irradiated from the projection lens 8 to the screen 1 is perpendicular to the plane of the screen 1, the upper and lower sides (or left and right) of the screen 1 have the same distance from the projection lens 8. There is no trapezoidal distortion in the image. However, in reality, as described above, the projector 2 is shifted downward or upward from the center of the screen so as not to disturb the viewer when illuminating from the front of the screen 1. The projection optical axis irradiated from the lens 8 to the screen 1 is inclined from the positional relationship perpendicular to the plane of the screen 1.
[0024]
For this reason, the distance from the projection lens 8 is different between the upper and lower sides of the screen 1, and thus a trapezoidal distortion occurs in the image projected on the screen 1. As described above, in order to correct the trapezoidal distortion, the inclination of the optical axis of the projection lens 8 is optically corrected, or a portion that is projected to be small (large) by the trapezoidal distortion is greatly enlarged (smallly reduced). The electrical correction for performing the image processing to be performed by the electric circuit is performed as described in Patent Document 1.
[0025]
However, in order to automatically perform these corrections, first, the inclination angle at which the optical axis of the projection lens 8 is inclined from the vertical direction of the plane of the screen 1, that is, the plane of the screen 1 with respect to the plane constituting the front of the projector 2. It is necessary to automatically and accurately measure the inclination angle of the plane.
[0026]
As will be described in detail below, the angle detection device of the present invention includes first and second passive type line-type distance measuring devices 3 and 4, and is horizontally (first passive) on the screen 1 from the front of the projector 2. By measuring the distance to a plurality of positions along the vertical direction (corresponding to the base line length direction of the second passive line type distance measuring device 4) and the vertical direction (corresponding to the base line length direction of the second passive type distance measuring device 4), The inclination angle of the plane of the screen 1 with respect to the plane constituting the front surface of the projector 2 can be accurately measured in the horizontal plane and the vertical plane.
[0027]
The first and second passive type line-type distance measuring devices 3 and 4 have calculation units 32 and 42, respectively, and output signals from the imaging units 31 and 41 are input, respectively. Output signals from the arithmetic units 32 and 42 are input to the control circuit 5 including the configuration of the present invention. The control circuit 5 controls the first and second passive line-type distance measuring devices 3 and 4, and also inputs a projected image from a device such as a personal computer (not shown) to output image information. And the display drive part 7 which outputs an image to the projection lens 8 is controlled. The control circuit 5 calculates the relative tilt angles of the screen 1 in the horizontal direction and the vertical direction, respectively, with respect to the plane constituting the front of the projector 2 based on the outputs from the calculation units 32 and 42 according to the present invention. Next, the control circuit 5 controls the projection image generation unit 6 and / or the display driving unit 7 so as to correct the trapezoidal distortion based on the calculated tilt angle, so that the screen 1 is moved up and down and / or left and right. Enlarge or reduce the projected image. However, as described above, trapezoidal distortion optical correction or electrical correction itself is known (see, for example, Patent Document 1) and will not be described further. The control circuit 5 and the arithmetic units 32 and 42 can be configured by one microprocessor (CPU) 9.
[0028]
The projector 2 includes a memory unit 10 and stores data and commands necessary for the configuration of the present invention. The projector 2 supplies the data and commands to the control circuit 5 and the arithmetic units 32 and 42 as needed, or the control circuit 5. Data is received from the arithmetic units 32 and 42 and the like. The memory unit 10 includes two types of memory devices such as a non-volatile flash memory and a volatile RAM, and instructions necessary for the present invention and long-term data are stored in the non-volatile memory device. Data that is only used temporarily is stored in a volatile memory device.
[0029]
Next, the configuration of the projector 2 according to the present embodiment will be described using functional blocks with reference to FIG. For the sake of brevity, only the configuration of the first passive line-type distance measuring device 3 will be described, but the second passive line-type distance measuring device 4 is similarly configured. Below the pair of lenses 31a and 31b, which are spaced apart by a base line length k (FIG. 4) in the horizontal direction on the plane constituting the front of the projector 2, the focal length f (FIG. 4) from these lenses 31a and 31b. The line sensors 31c and 31d are arranged along the base line length k (FIG. 4). The line sensors 31c and 31d are a pair of line CCDs or other line type image pickup elements each having a predetermined number (for example, 162) of light detection elements (pixels) arranged linearly. An electrical signal corresponding to the light amount of the image formed on each pixel of the line sensors 31c and 31d by the lenses 31a and 31b is output in series from the imaging unit 31 via the output unit 31e.
[0030]
The A / D conversion unit 32a converts the analog electrical signal output from the output unit 31e of the imaging unit 31 into a digital signal. The digitized output signals from the line sensors 31c and 31d are stored as video data signal strings IL and IR, respectively, in the memory area 32b for subsequent processing. Accordingly, for example, a pair of video data signal strings IL and IR each consisting of 162 data strings are stored in the memory area 32b. The memory area 32 b may be provided in the memory unit 10.
[0031]
The filter processing unit 32c removes the direct current component from the line sensor output signal (filing), and converts it into a useful signal including only the spatial frequency component corresponding to the image into the video data signal sequences IL and IR. As will be described later with reference to FIGS. 4 and 5, the correlation calculation unit 32 d performs a partial video data group iLm (for example, 27 pixel groups spatially close from the video data signal sequences IL and IR. The reference part) and iRn (reference part) are selectively extracted, and the partial video data groups iLm and iRn are compared with each other in order to calculate the degree of coincidence of the data. For example, the comparison is repeated while fixing one partial video data group iLm as a reference part and even one pixel at a time in the IR using the other partial video data group iRn as a reference part. The maximum correlation degree detection unit 32e detects two partial video data groups iLm and iRn having the highest data matching degree in the pair of video data signal sequences IL and IR.
[0032]
The interpolation calculation unit 32f determines the position interval of the partial video data groups iLm and iRn having the highest degree of coincidence obtained by the maximum correlation degree detection unit 32e by a known interpolation method more accurately than the position interval in pixel pitch units. Interpolate to intervals. Based on the position interval interpolated by the interpolation calculation unit 32f, the phase difference detection unit 32g makes a relative shift between a pair of images of the same distance measuring object imaged on the pair of line sensors 31c and 31d. Calculate the quantity (phase difference).
[0033]
As will be described later with reference to FIG. 12, the contrast centroid calculating unit 32h obtains the contrast centroid of the images formed on the line sensors 31c and 31d. The reliability determination unit 32i determines the reliability of the relative shift amount (phase difference) between the positions imaged on the calculated line sensors 31c and 31d. For example, if the object whose distance is to be measured is correctly imaged on both line sensors 31c and 31d, the degree of coincidence obtained in the maximum correlation degree detection unit 32e is equal to or greater than a predetermined value. Should be. Therefore, even if the degree of coincidence obtained in the maximum correlation degree detection unit 32e is relatively highest, if the degree of coincidence is less than a predetermined value, the reliability judgment unit 32i determines that the reliability is low. Eliminate results. If the degree of coincidence obtained by the maximum correlation degree detection unit 32e is equal to or greater than a predetermined value, the data is reliable and CONF_FLG1 = OK is set. The above-described configurations of the imaging unit 31 and the calculation unit 32 are well known, and are described in, for example, Patent Document 2 and Patent Document 3, and thus further description thereof is omitted.
[0034]
[Patent Document 2]
Japanese Patent No. 3230759
[Patent Document 3]
Japanese Patent Publication No. 4-77289
[0035]
The calculation unit 32 further includes an averaging unit 32j. The averaging unit 32j is connected to the reliability determination unit 32i, and the reliability determination unit 32i is obtained from the result of measuring each distance measurement area (for example, each of the 11 distance measurement areas) of the line sensor 31c a plurality of times. Averages the measurement results determined to be reliable and outputs this average value to the control circuit 5. The averaging unit 32j is also connected to the contrast centroid calculating unit 32h, and the contrast centroid calculating unit 32h performs a plurality of times for each ranging area (for example, each of the 11 ranging areas) of the line sensor 31c. The contrast centroid position as a result of the measurement is averaged, and this average value is output to the control circuit 5. In this way, the averaging unit 32j stores a plurality of distance measurement results and contrast centroid position calculation results for each distance measurement area (for example, each of the 11 distance measurement areas) of the line sensor 31c, These average values are calculated and output to the control circuit 5.
[0036]
The projector 2 further includes a control circuit 5 according to the embodiment of the present invention. As will be described in detail later, the control circuit 5 includes a mutual reliability determination unit 51 for determining the reliability of the distance measurement results of a small group of several adjacent measurement positions, and several adjacent measurements. An average value calculation unit 52 that calculates an average value of a distance measurement result and a contrast centroid for a small group of positions, and performs a correlation calculation using a least square method to determine an inclination angle from the distance measurement result, and performs a calculation between multiple distance measurement results An angle calculation unit 53 that performs an approximate calculation for obtaining a straight line representing the correlation and obtains the inclination angle of the screen 1 to be measured from the angle of the obtained straight line is included. In addition, as will be described in detail later, the angle calculation unit 53 lowers a perpendicular line on the first straight line obtained by extending the base line from the measurement position of the screen 1 to be measured in order to obtain the angle of the straight line representing the correlation. An operation for obtaining the position coordinates of the intersection is also performed. Based on the tilt angle of the screen 1 calculated by the angle calculation unit 53 in this way, a correction amount for correcting the trapezoidal distortion is given to the projection image generation unit 6 and / or the display drive unit 7. Thereby, the trapezoidal distortion on the screen 1 is corrected.
[0037]
Further, as will be described in detail later with reference to FIGS. 18 and 19, the control circuit 5 sets the number of distance measurements when the distance measurement result is larger than the first set value. When the tilt angle calculated based on the distance measurement result is larger than the second set value, the number of times of tilt angle measurement is calculated. A measurement number adjusting means 55 is provided for increasing the measurement error of the tilt angle by increasing it compared to the case of the second set value or less. The memory unit 10 is connected to a microprocessor (CPU) 9 and stores and provides instruction codes and data necessary for this embodiment.
[0038]
Next, the operation principle (external light triangular distance measuring method) of the passive line type distance measuring devices 3 and 4 will be described with reference to FIG. The first passive line-type distance measuring device 3 includes a pair of lenses 31a and 31b that extend in the horizontal direction on the plane that constitutes the front surface of the projector 2 and are separated from each other by a base length k, and from the base length k to the lenses 31a and 31b. It includes a pair of line sensors 31c and 31d that are separated by a focal length f of 31b and extend along the same horizontal direction as the baseline length k direction. The first passive type line-type distance measuring device 3 measures the distance between a plurality of positions on the plane of the screen 1 located in a plane (horizontal plane) including the baseline length k and the line sensors 31c and 31d, In a plane (horizontal plane) including k and the line sensors 31c and 31d, a relative inclination angle between the front of the projector 2 and the plane of the screen 1 is calculated.
[0039]
On the other hand, the second passive line-type distance measuring device 4 includes a pair of lenses 41a and 41b spaced apart by a base line length k ′ (not shown) extending in the vertical direction on a plane constituting the front surface of the projector 2. A pair of line sensors 41c (not shown) and 41d (not shown) that are separated from the baseline length k ′ by the focal length f of the lenses 41a and 41b and extend along the same vertical direction as the baseline length k ′ direction. Contains. The second passive line type distance measuring device 4 is a screen located in a plane (vertical surface) including a base line length k ′ (not shown) and line sensors 41c (not shown) and 41d (not shown). The distance between a plurality of positions on one plane is measured, and the relative distance between the front surface of the projector 2 and the plane of the screen 1 in the plane (vertical plane) including the base line length k ′ and the line sensors 41c and 41d. Calculate the correct tilt angle.
[0040]
For the sake of brevity, only the first passive line-type distance measuring device 3 will be described here, and the description of the second passive line-type distance measuring device 4 will be omitted, but the operating principle is the same. Therefore, the same description can be applied to the second passive line type distance measuring device 4 only by replacing the horizontal direction with the vertical direction.
[0041]
In FIG. 4A, a pair of lenses 31 a and 31 b are arranged apart from each other by a predetermined baseline length k extending in the horizontal direction on a plane constituting the front surface of the projector 2. A pair of line sensors 31c and 31d, which are separated from the pair of lenses 31a and 31b by their focal length f and extend in the base length k direction (horizontal direction), are below the plane that forms the front of the projector 2. Has been placed. The line sensors 31c and 31d are arranged so that the central portions thereof are substantially positioned on the optical axes 31ax and 31bx of the lenses 31a and 31b, respectively, and the corresponding lenses 31a and 31b are respectively provided on the line sensors 31c and 31d. As a result, an image 1A at a certain position on the screen 1 for distance measurement is formed.
[0042]
In FIG. 4A, the measurement position 1A on the screen 1 is imaged on the line sensors 31c and 31d through the optical paths A and B in different directions and through the respective lenses 31a and 31b. .
[0043]
If it is assumed that the measurement position 1A exists at an infinite position, the measurement position 1A is on the line sensors 31c and 31d at the focal length f from the pair of lenses 31a and 31b. An image is formed at reference positions 31cx and 31dx intersecting the axes 31ax and 31bx.
[0044]
Next, when the measurement position 1A approaches from the infinity position along the direction A on the optical axis 31ax of the lens 31a and reaches the position of FIG. 4A, that is, the distance LC, the measurement position 1A is on the line sensor 31c. In FIG. 2, the image is still formed on the reference position 31cx, but on the line sensor 31d, the lens 31b forms an image at a position shifted by the shift amount α from the reference position 31dx.
[0045]
From the principle of triangulation, the distance LC to the measurement position 1A is obtained by LC = kf / α. Here, the base line length k and the focal length f are known values that are known in advance, and the distance LC can be measured by detecting the shift amount α from the reference position 31dx on the line sensor 31d. This is the operating principle of a passive line sensor distance measuring device for external light triangulation. The detection of the shift amount α and the calculation of LC = kf / α are executed by the calculation unit 32 in FIG.
[0046]
That is, the detection of the shift amount α from the reference position 31dx of the line sensor 31d is performed for the partial video data groups iLm and iRn extracted from the pair of video data signal sequences IL and IR output from the pair of line sensors 31c and 31d, respectively. The calculation unit 32 detects the correlation calculation. This correlation calculation is well known (for example, see Patent Document 2).
[0047]
For this reason, detailed description of the correlation calculation is omitted, and only the following general description is given. As shown in FIG. 4 (b), the correlation calculation is performed by using the line sensors 31c and 31d as the line sensors 31c and 31d for the partial video data groups iLm and iRn to be overlapped. This is a calculation that is detected while relatively shifting. In FIG. 4B, the position of the partial video data group iLm from one line sensor 31c is fixed to the reference position 31cx and used as the reference portion. The partial video data group iRn from the other line sensor 31d is shifted one pixel at a time as a reference portion, and the partial video data group iRn having the highest degree of coincidence with the reference portion is searched. The distance between the position on the line sensor 31d that generates the partial video data group iRn having the highest degree of coincidence and the reference position 31dx of the line sensor 31d is the shift amount α.
[0048]
Since each of the line sensors 31c and 31d is composed of a pair of line CCDs in which a predetermined number of photodetector cells (pixels) are arranged on a straight line having a predetermined length as will be described later, the shift amount α is a partial image. It can be easily obtained from the pixel position and pixel pitch in the video data signal sequence IR of the data group iRn. In this way, the distance LC to the measurement position 1A in the same direction A as the optical axis 31ax of the lens 31a can be measured by detecting the shift amount α.
[0049]
Next, the principle of measuring the distances LR ′ and LR to the measurement position 1B in a direction different from that in FIG. 4 will be described with reference to FIG. As shown in FIG. 5A, the measurement position 1B passes through the optical path C and the optical path D in different directions, and is imaged on the line sensors 31c and 31d via the respective lenses 31a and 31b.
[0050]
If it is assumed that the measurement position 1B exists at an infinite position in the direction C to be measured, the center of the image of the measurement position 1B formed on the pair of line sensors 31c and 31d by the pair of lenses 31a and 31b The reference positions 31cy and 31dy are separated from each other by the base line length k. Next, when the measurement position 1B at the infinity position approaches along the distance measurement direction C and reaches the position shown in FIG. 5A, the image of the measurement position 1B formed by the lens 31a on the line sensor 31c. However, the position on the line sensor 3dc of the image of the measurement position 1B formed by the lens 31b is shifted from the reference position 31dy by the shift amount α ′.
[0051]
From the principle of triangulation, the distance LR to the measurement position 1B is LR = kf / (α′cos β). The angle β is an inclination angle of the distance measuring direction C with respect to the vertical line of the base length k, that is, the optical axis 31ax of the lens 31a, and is an angle determined by determining the measuring direction C. Since the base line length k, the focal length f, and cos β are known values, the distance LR can be measured by detecting the shift amount α ′.
[0052]
The distance LR ′ from the same plane (baseline length k direction) constituting the front surface of the projector 2 on which the lenses 31a and 31b are arranged to the measurement position 1B is obtained by LR ′ = LR cos β = kf / α ′. That is, the distance LR ′ can be obtained from the baseline length k and the focal length f, which are known values, by detecting the shift amount α ′. That is, in order to measure the distance LR ′, the angle β is not necessary.
[0053]
In order to detect the shift amount α ′, the above-described correlation calculation is performed. As shown in FIG. 5B, the position is fixed with the partial video data group iLm corresponding to the reference position 31cy from one line sensor 31c as a reference portion, and the partial video data group iRn from the other line sensor 31d is fixed. The reference part iRm having the highest degree of coincidence with the data of the reference part iLm is found by shifting the positions one pixel at a time as the reference part and superimposing each other.
[0054]
Each of the line sensors 31c and 31d is composed of a pair of line CCDs in which a predetermined number of photodetector cells (pixels) are arranged in a predetermined length on a straight line, as will be described later. It can be easily obtained from the position (pixel number) in the video data signal sequence IR of the video data group iRn, the position (pixel number) in the video data signal sequence IL of the partial video data group iLm, and the pixel pitch.
[0055]
In the correlation calculation method described above, the partial video data group iLm from one line sensor 31c is fixed as a reference part, and the partial video data group iRn from the other line sensor 31d is used as a reference part, and the position is set to one pixel. We decided to inspect each other for the high degree of coincidence. However, when the distance measuring direction is the direction from the intermediate position between the lenses 31a and 31b, the partial video data is moved while moving the positions of the partial video data groups iLm and iRn in the opposite directions on the line sensors 31c and 31d. You may make it test | inspect the height of a mutual agreement between group iLm and iRm.
[0056]
Next, one line sensor 31c of the pair of line sensors 31c and 31d will be described in detail with reference to FIG. The other line sensor 31d is configured similarly to the line sensor 31c. As shown in FIG. 6, the line sensor 31c is composed of a large number, for example, a linear CCD (charge coupled device) in which 162 photodetector cells (pixels) are linearly arranged, or another linear imaging device. Yes. The 162 photodetector cells (pixels) are sequentially assigned pixel numbers from the left end to the right end in FIG. 6, and are arranged at a constant pixel pitch interval. These photodetector cells (pixels) have 11 ranging calculation areas 31c1 (1-27), 31c2 (14-40), 31c3 (28-54), 31c4 (41) by groups of 27 adjacent units. -67), 31c5 (55-81), 31c6 (68-94), 31c7 (82-108), 31c7 (82-108), 31c8 (95-121), 31c9 (109-135), 31c10 (122- 148) and 31c11 (136-162). However, the number in parentheses is the photodetector cell (pixel) number. Each of the distance measurement calculation areas 31c1 to 31c11 is included in the 27 photodetector cells, and the first half is included in the distance measurement calculation area adjacent to the front and the second half is included in the distance measurement calculation area adjacent to the rear. The distance calculation areas 31c1 to 31c11 overlap each other with the distance calculation areas adjacent to each other almost by half.
[0057]
Signals from the photodetector cells (pixels) in the distance measurement calculation areas 31c1 to 31c11 correspond to the partial video data groups iLm of the video data signal sequence IL of the line sensor 31c in FIGS. Center positions a (14), b (28), c (41), d (55), e (68), f (82), g (95), h (109) of the distance measurement calculation areas 31c1 to 31c7 , I (122), j (136), and k (148) (however, the numbers in parentheses are pixel numbers) serve as reference positions for determining the distance measurement direction. As a result, the distance measuring device 3 using the line sensors 31c and 31d of the present embodiment measures the distance to 11 spaced positions on the screen 1 that are in the same plane (horizontal plane) as the reference line k. be able to. However, the actual ranging direction can be corrected by the contrast centroid position in the ranging calculation area as will be described later by the contrast centroid calculating unit 32h in FIG. FIG. 6 shows reference positions a ′, b ′, c ′, d ′, e ′, f ′, g ′, h ′, i ′, j ′, and k ′ corresponding to the other line sensor 31d. As a reference portion, it is used when obtaining a deviation amount when performing correlation calculation with the distance measurement calculation area in the line sensor 31c.
[0058]
A plurality of different positions on the screen 1 for distance measurement according to the present invention need not be limited to 11, but may be appropriately set to an appropriate number, for example, 7, the number of pixels of the line sensors 31c and 31d or the distance calculation calculation area. This is possible by selecting an appropriate number.
[0059]
Next, a description will be given with reference to FIG. FIG. 7 shows a state in which the mutual positional relationship of the screen 1 of the projector 2 is set to a predetermined positional relationship in order to perform the initial adjustment of the line type distance measuring devices 3 and 4. That is, the screen 1 is made parallel to the base line lengths k and k ′ (not shown) so that the projection optical axis from the projector 2 is perpendicular to the screen 1, and the line distance measuring device 3 and 4 project an image suitable for the initial adjustment. In the initial adjustment, for example, the lenses 31a and 31b have aberration. For this reason, when different measurement positions along the base line length k direction on the screen 1 are imaged on the line sensors 31c and 31d, they are not imaged on a straight line but actually distorted. In the initial adjustment, a correction coefficient for correcting the distortion due to the lens aberration is calculated, stored in the memory unit 10, and used by the subsequent calculation units 32 and 42. The line-type distance measuring device 3 measures the distance on the screen 1 in 11 distance measuring directions using 11 distance calculating areas 31c1 to 31c11 on the line sensor 31c. For the sake of brevity, among the 11 directions in FIG. 7, 1C, 1E, 1G on the screen 1 in the three distance measuring directions corresponding to the three distance calculating areas 31c3, 31c5, 31c7 on the line sensor 31c. Only the position of is shown.
[0060]
The passive line type distance measuring device 3 measures an inclination angle with respect to the base line length k direction of the plane of the screen 1 in the horizontal plane, and the passive line type distance measuring device 4 has a base line length k ′ (not shown) of the plane of the screen 1 in the vertical plane. ) Measure the tilt angle of the direction. For the sake of brevity, only the measurement of the inclination angle with respect to the base line length k direction of the plane of the screen 1 on the horizontal plane by the passive line type distance measuring device 3 will be described. However, the description of the present embodiment is similarly applied to the measurement of the inclination angle in the vertical plane of the screen 1 by the passive line type distance measuring device 4.
[0061]
Next, a reference method for measuring the tilt angle of the screen 1 using the passive line type distance measuring device 3 will be described with reference to FIGS. 8 to 11. For simplification of description, two distance measurement directions C and G of the two distance calculation calculation areas 31c3 and 31c7 of the line sensor 31c are used, and 2 on the plane of the screen 1 in the two distance measurement directions C and G are used. Two distances LR ′ and LL ′ to the two measurement positions 1C and 1G are measured by the method described in FIG. In the present embodiment, only two distances LR ′ and LL ′ are measured, but actually, distances to 11 measurement positions on the screen 1 in 11 distance measurement directions are measured.
[0062]
If the measurement positions 1C and 1G on the screen 1 are images suitable for passive distance measurement, the manufacturer's logo that is first projected onto the screen 1 via the projection lens 8 when the projector 2 is powered on. An image including a mark or the like may be used, and when the angle detection operation is periodically performed during the operation of the projector 2, the measurement positions 1C and 1G on the screen 1 are arbitrary images projected on the screen 1. It may be.
[0063]
The distance L between the reference positions c (41) and g (95) in the distance measurement directions C and G of the two distance measurement calculation areas 31c3 and 31c7 of the line sensor 31c is determined by the pixel number and the pixel pitch in the parentheses. It is a value known in advance.
[0064]
When a point that is perpendicular to the measurement position 1C on a straight line k1 that is parallel to the base line length k and passes through the measurement position 1G is C ′, the distance between the measurement position 1C and the point C ′ is LR′−LL ′. equal. When the tilt angle θ1 of the screen 1 is not so large, the magnitude of this LR′−LL ′ is defined as a point C ”with a point at a distance (LL ′ * L / f) from the measurement position 1G on the straight line k1 as C ″. Can be approximated to a distance 1C'-C "in the case of an intersection 1C 'between the line perpendicular to the straight line k1 from the screen 1 and the screen 1. Usually, the relative positional relationship between the screen 1 and the projector 2 by hand or the like in advance. Is often adjusted, the inclination angle θ1 does not increase so much and this approximation is appropriate in many cases. A triangle composed of a measurement position 1G, a point C ″ and the center of the lens 31a and a reference The triangle formed by the positions c and g and the center of the lens 31a has a similar relationship, and the two reference positions c (41) and g (95) of the two distance measurement calculation areas 31c3 and 31c7 on the line sensor 31c. ) L, since then corresponds to the distance between the measurement position 1G~ point C ", the value of the inclination angle θ1, using the relationship and trigonometric functions similar shape,
θ1 = arctan {(LR′−LL ′) / (LL ′ * L / f)}
It can be asked.
[0065]
Therefore, the control unit 5 of the projector 2 can calculate the inclination angle θ1 in the base line length k direction of the screen 1 and the projector 2 in the horizontal plane by calculating the above equation. Based on the magnitude of the inclination angle θ1, the control circuit 5 in FIG. 1 can give an instruction to the projection image generation unit 6 and / or the display drive unit 7 to correct the trapezoidal distortion of the image. However, the inclination angle θ1 obtained from the above equation depends on the accuracy of the distance measurement results LR ′ and LL ′ to the measurement positions 1G and 1C.
The measurement errors of the distance measurement results LR ′ and LL ′ tend to increase as the distance increases. Therefore, in the present invention, if the distance measurement result is larger than a predetermined value, for example, 10 m, the distance measurement result is increased as compared with the case where the distance measurement result is less than the predetermined value. The average value or the median value excluding the maximum value and the minimum value or the average value of the measurement results excluding the maximum value and the minimum value is obtained to reduce the error of the distance measurement result.
Similarly, the measurement error of the obtained inclination angle θ1 tends to increase as the inclination angle increases. Therefore, in the present invention, if the obtained inclination angle θ1 is larger than a predetermined value, for example, 15 degrees, the inclination angle θ1 is measured as compared with the case where the obtained inclination angle θ1 is less than the predetermined value. By increasing the number of times, the average value of the measurement results or the median value excluding the maximum and minimum values or the average value of the measurement results excluding the maximum and minimum values is obtained, so that the error of the inclination angle θ1 is reduced. ing.
[0066]
In FIG. 8, the measurement distance is changed from the measurement position 1C and 1G to the base line length k direction in place of the lengths of the vertical lines LR ′ and LL ′. The length may be up to the measurement positions 1C and 1G. This case will be described with reference to FIG.
[0067]
If high accuracy is required for angle detection, each measurement is performed instead of the distance L between the reference values c (41) and g (95) of the two distance calculation calculation areas 31c3 and 31c7 used for angle detection. The distance of the contrast centroid position in the distance calculation areas 31c3 and 31c7 may be used.
[0068]
With reference to FIG. 12, distance measurement using the contrast centroid position by the contrast centroid calculating unit 32h of FIG. 3 will be described. As is well known, passive line-type distance measurement includes an operation of detecting a place where the degree of coincidence is highest when a pair of images formed on two line sensors are overlapped. This is to detect whether or not the contrast states of the pair of images match.
[0069]
Therefore, in the passive type line-type distance measurement, if the design distance measurement direction of one distance measurement calculation area 31cn is the arrow J direction as shown in FIG. 12, the image is formed on the distance measurement calculation area 31cn. When the image of the object to be measured is an image in which the contrast position 1K exists only in the arrow K direction, the actual distance measuring direction is shifted from the arrow J direction to the arrow K direction. If the distance measurement target image formed on the distance measurement calculation area 31cn is an image in which the contrast position 1M exists only in the arrow M direction, the actual distance measurement direction is shifted from the arrow J direction to the arrow M direction. . Further, when the image of the distance measurement object formed on the distance measurement calculation area 31cn is an image in which the contrast positions 1K and 1M exist in the arrow K direction and the arrow M direction, the actual distance measurement direction is from the arrow J direction. It shifts to the contrast centroid position of the image formed on the measurement calculation area 31cn.
[0070]
Therefore, if the distance of the contrast centroid position in each distance measurement calculation area is used as a value corresponding to the distance between the two distance calculation calculation areas used for angle detection, a highly accurate distance L can be used. Angle detection accuracy is improved. In addition, the method of calculating | requiring a contrast gravity-center position is described in patent document 4, and is well-known.
[0071]
[Patent Document 4]
JP-A-8-75985
For reference, Equation 1 for obtaining the contrast barycentric position in the present embodiment is shown below.
[0072]
[Expression 1]

Where L (): reference side sensor data
Sa: Reference start address
Wn: number of calculation windows
t: integer (generally 1 to 4)
In order to eliminate the influence of noise, when the absolute value of the difference is equal to or less than a predetermined value (noise cancellation level), it is not added to the sum.
[0073]
Next, a method of calculating the tilt angle θ1 using the passive line type distance measuring device 3 according to another reference method will be described with reference to FIG. As shown in FIG. 13, the inclination angle of the screen 1 with respect to the base line length k direction (the horizontal direction of the projector 2) of the passive line type distance measuring device 3 is θ1, and the line sensor 31c is measured by the method described in FIG. The distance to the screen 1 calculated by measuring the distance along the distance measuring direction of the distance calculating area 31c7 is L1, and the distance to the screen 1 calculated by measuring the distance along the distance measuring direction of the distance calculating area 31c3 is calculated. Is a distance L2. The angle formed by the distance measurement direction of the distance measurement calculation area 31c3 known in advance and the direction perpendicular to the baseline length direction is β, and the distance measurement direction of the distance measurement calculation area 31c7 also known in advance is the same as the baseline length direction. Let γ be the angle between the vertical direction. The inclination angle θ1 is calculated by the following equation.
[0074]
θ1 = arctan (L2cosβ−L1cosγ) / (L1sinγ + L2sinβ)
[0075]
Next, a description will be given with reference to FIG. The distance measuring direction in which the distance is measured by the passive line type distance measuring device 3 according to the present embodiment is, for example, 11 as shown in FIG. 6 when the line sensor 31c has, for example, 162 pixel columns. In FIG. 14, only seven distance measuring directions are shown as examples for the sake of brevity. FIG. 14 shows the lengths of perpendiculars drawn down to straight lines extending the base line length k from seven positions 1A, 1B, 1C, 1D, 1E, 1F, and 1G on the screen 1 to be measured in the seven distance measuring directions. Measured as distance. Thus, in the present invention, the distance measurement results are obtained from, for example, seven measurement positions 1A, 1B, 1C, 1D, 1E, 1F, and 1G on the screen 1 plane along the base length k direction (horizontal direction), respectively. This is the length of a perpendicular line drawn on a straight line obtained by extending the base line length k (for example, the length corresponding to LR ′ in FIG. 5 or LL ′ and LR ′ in FIG. 8). Based on the distance measurement result measured by the passive line-type distance measuring device 3, the projector 2 tilts the screen 1 with respect to the main surface of the projector 2 in the horizontal (baseline length k) direction. θ1 is calculated by the method described above with reference to FIG.
[0076]
However, the length of the vertical line (for example, LR ′ in FIG. 5 or LL ′ and LR ′ in FIG. 8) dropped on a straight line obtained by extending the base line length k from a plurality of measurement positions by the passive line-type distance measuring device 3. When the distance is measured, the distance measurement result is corrected even if it is corrected so as to obtain an accurate measurement value by means such as reliability determination by the reliability determination unit 32i of FIG. 3 or the averaging unit 32j of FIG. As shown in FIG. 15A, the contrast centroid position is measured as the distance at the position of the round point indicated by the horizontal axis and the measured distance (range measurement result) on the vertical axis. In FIG. 15A, only the measurement results at the four measurement positions 1D, 1E, 1F, and 1G are shown for the sake of brevity.
[0077]
When the distance measurement result is the length of a perpendicular line drawn down from a plurality of measurement positions on the plane of the screen 1 in the base line length k direction (LR ′ in FIG. 5 or LL ′, LR ′ in FIG. 8) Case), it should change linearly. However, the actual distance measurement result does not change linearly as shown in the measurement results 1D, 1E, 1F, and 1G of the four round points in FIG. Such deviation from the linear relationship is caused by a manufacturing error, noise at the time of measurement, or the like.
[0078]
When using the method for obtaining the inclination angle θ1 described in FIG. 8 or FIG. 13, the two measurement positions necessary for calculating the inclination angle θ1 are the four round points 1D, 1E, 1F, FIG. The measured value shown in 1G is used. For example, if 1G is used as the reference point 1 and the adjacent measurement point 1F is used, the inclination angle θ1 ′ is obtained, and if 1F is used as the reference point 2 and the adjacent measurement point 1E is used, the inclination angle θ1 ″ is obtained, and 1E Is used as a reference point 3 and the adjacent point 1D is used, an inclination angle θ1 ″ ′ is obtained. Depending on how to select the reference point and another measurement point, the inclination angle obtained in the method for obtaining the inclination angle described with reference to FIG. 8 or FIG. 13 may be different. In order to obtain the inclination angle θ1 of the screen 1 from the different inclination angles θ1 ′, θ1 ″, and θ1 ″ ′ as described above, the maximum value and the minimum value are obtained from the different inclination angles θ1 ′, θ1 ″, and θ1 ″ ′. Further processing must be performed, such as obtaining an intermediate value excluding the value or an average value thereof. Thus, it is difficult to uniquely calculate the accurate inclination angle θ1 of the screen 1 from a plurality of distance measurement results.
[0079]
Therefore, as a method for accurately obtaining the inclination angle θ1, a constant correlation (distribution), that is, linear alignment is made between the measurement values of a plurality of measurement positions linearly aligned on a planar measurement target. Is obtained by approximating a straight line representing the correlation (distribution) of the plurality of measured values, and the screen inclination angle θ1 is obtained from the inclination of the straight line obtained by the approximation.
[0080]
As shown in FIG. 15B, in the present invention, a correlation between distance measurement results of a plurality of measurement positions arranged linearly on the plane of the screen 1, that is, a straight line y = ax + b representing a distribution is approximated. Ask. Here, x represents a coordinate position on a straight line obtained by extending the baseline length k (that is, the horizontal axis in FIG. 15B), and y represents a distance from the baseline length k to a position on the screen 1 (that is, In FIG. 15B, the vertical axis), a represents the slope of this straight line y. The inclination a of the straight line y is the inclination angle θ1 of the screen 1 to be obtained. That is, a = θ1. In order to obtain the straight line y by approximation from the distribution of the measurement results at a plurality of measurement positions, that is, from the correlation, the least square method is used.
As shown in FIG. 15B, the least square method used in the present embodiment represents the measurement result at each measurement position corresponding to 1G, 1F,... The points are P1, P2,..., Pn, and a line drawn vertically to the horizontal axis in FIG. 15 (b) corresponding to a straight line obtained by extending the base line length k from each point P1, P2,. When the intersections with ax−b are Q1, Q2,..., Qn, the slope a of the straight line y = ax + b is set so that the total sum Σ of the lengths of the respective line segments P1Q1, P2Q2,. The value of b is obtained.
[0081]
A method of obtaining the slope a of the straight line y = ax + b representing the correlation (distribution) of a plurality of measurement results by the least square method is well known.
[0082]
For example, the points P1, P2,..., Pn representing the measurement results at a plurality of n measurement positions on FIG. 15B are respectively (x1, y1), (x2, y2),. (Xn, yn).
The average value of x coordinate values of the plurality of n measurement results points P1, P2,..., Pn is xm = (x1 + x2 +... + Xn) / n, and the average value of y coordinate values is ym = (y1 + y2 +... + Yn) / Let n.
The variance of the x-coordinate values of these plural n points P1, P2,. ² x = [(x1-xm) ² + (X2-xm) ² + ... + (xn-xm) ² ] / N, and the variance of the y coordinate value is δ ² y = [(y1-ym) ² + (Y2-ym) ² + ... + (yn-ym) ² ] / N and the covariance is [delta] xy = [(x1-xm) (y1-ym) + (x2-xm) (y1-ym) + ... + (xn-xm) (yn-ym)] / n. .
The correlation coefficient is ρxy = δxy / δxδy.
According to the least square method, the slope a of the straight line y = ax + b representing the correlation (distribution) of a plurality of n measurement results can be obtained from the relationship a = δyρxy / δx. On the other hand, b is obtained from the relationship b = ym−xmδyρxy / δx.
The inclination angle θ1 of the screen 1 is θ1 = tan from the inclination a. ^-1 It is calculated | required from the relationship of a.
[0083]
The plurality of n measured values are inherently changing in a substantially linear relationship, and one inclination angle θ1 should be uniquely calculated from this linear change. However, in practice, due to various causes such as noise and manufacturing error, the measured distances are not arranged linearly but arranged like a line graph as shown in FIG. To solve this problem, use the correlation that when measuring the distance to multiple positions on a planar object to be measured, the distance measurement results are linearly distributed. The straight line y = ax + b that minimizes the error due to the distance measurement at the position of is calculated using the least square method, and the inclination a of the straight line y is used as the inclination angle of the screen 1.
[0084]
FIG. 16 schematically shows ranging operation areas 31c1 to 31c11 used for measuring the distance in the line sensor 31c of the passive line-type distance measuring device 3 shown in FIG. The calculation areas 31c1 to 31c11 in the line sensor 31c according to the present embodiment have a relationship of sharing approximately half the number of pixels with the adjacent calculation areas. For example, the region 31c1 and the region 31c2 share approximately half the number of pixels, and the region 31c2 and the region 31c3 share approximately half the number of pixels. FIG. 16 is a schematic diagram showing the overlapping relationship of pixels between the distance measurement calculation areas 31c1 to 31c11 in the line sensor 31c of FIG. 6 used in this embodiment.
[0085]
In the case where a plurality of linearly arranged positions on a plane such as the screen 1 are measured by a line sensor 31c having distance calculation calculation areas 31c1 to 31c11 as shown in FIG. 16, the distance measured by the area 31c1; Regarding the relationship between the distance measured by the region 31c2 and the distance measured by the region 31c3, the average value of the distances measured by the region 31c1 and the region 31c3 is equal to the distance measured by the region 31c2. This is because the measurement object is a planar object, and the distance measurement results up to the position linearly arranged on the object have a linear relationship. That is, the distance measurement results have a correlation. This correlation results from the fact that the measurement object is a planar object.
[0086]
In general, the Nth distance calculation calculation area, the N + 1th distance calculation calculation area, and the N + 2th distance calculation calculation area of such a line sensor follow a certain straight line on a plane object such as the screen 1. When the distance is measured at a plurality of positions, the average value S of the measurement distance by the Nth region and the measurement distance by the N + 2th region should be almost equal to the measurement distance T by the N + 1th region in the middle. According to the present invention, using the above principle, the distance measurement result T of the intermediate distance measurement calculation area is equal to or greater than the average value S of the adjacent distance calculation calculation areas and a predetermined determination value from the distance measurement results of the plurality of distance calculation calculation areas. If they are separated (| T−S | ≧ determination value or | T / S−1 | ≧ determination value), it is determined that the distance measurement results in these distance measurement calculation areas are not reliable, This is excluded from the subsequent arithmetic processing. The magnitude of the determination value can be selected as appropriate according to the purpose.
[0087]
Further, the N-th distance calculation calculation area, the N + 1th distance calculation calculation area, and the N + 2th distance calculation calculation area of such a line sensor are adjacent to each other along a straight line on a plane object such as the screen 1. The average of the measurement results when measuring the distance of the measured positions can reduce the influence of manufacturing errors in individual measurement calculation areas (areas) and noise during measurement. That is,
(1) The average of the centroid positions of the contrast distributions for the N, N + 1, and N + 2 areas is detected by the averaging process for the contrast centroid positions of the individual areas.
(2) The average of the distance measurement results for the N, N + 1, and N + 2 areas is detected by the averaging process for the distance measurement results of the individual areas.
[0088]
The above two averaging processes (1) and (2) are performed for the small groups N, N + 1, N + 2 (N = 1 to 4 natural numbers) of the measurement results in FIG. In FIG. 17A, the small groups of the measurement results are four small groups each including three distance measurement calculation areas. The number of distance calculation calculation areas adjacent to each other and the small groups included in this small group. The number of can be chosen freely.
[0089]
FIG. 17B is a graph in which the average value of the distance measurement results for each small group (N = 1 to 4) is shown on the vertical axis, and the average position of the center of gravity of the contrast distribution for each small group is shown on the horizontal axis. is there. When comparing FIG. 17 (a) and FIG. 17 (b), as can be easily understood, the graphs of the averaged values of the three distance measurement calculation areas are arranged almost on a straight line. Therefore, if the inclination angle θ1 of the screen 1 is calculated from the averaged values in FIG. 17B using the least square method as described above, a more accurate angle can be detected.
[0090]
Note that when the projection optical system of the projector 2 has an autofocus mechanism, and automatically detects the distance to the screen 1 and performs autofocus on the image projected on the screen 1, As the distance, a median value excluding the maximum value and the minimum value or an average value thereof can be selected from the average values of the distance measurement results shown in FIG. Alternatively, when the distance measurement result of the distance measurement calculation area 31c6 at the center of the line sensor 31c has a linear relationship with the distance measurement result of the adjacent distance calculation calculation areas, it may be used. In this way, a more accurate distance can be detected and accurate automatic focusing can be performed.
[0091]
Next, the operation of the angle detection apparatus of the present invention will be described with reference to FIGS.
[0092]
First, FIG. 18 will be described with reference to FIG. When power is supplied to the projector 2 or when a periodic angle detection operation is started during the operation of the projector 2, the control circuit 5 determines whether input image data is input from an external personal computer (not shown) or the like. If there is external input image data, the projection image generation unit 6 outputs display data corresponding to the image data, and the image is displayed on the screen 1 via the display drive unit 7 and the projection optical system. Project. If there is no input image data, the control circuit 5 outputs the contrast image data for adjustment stored in the projector 2 in advance (for example, appropriate image data including a logo mark or the like) to the projection image generation unit 6. The image is projected onto the screen 1 via the display drive unit 7 and the projection optical system, and the angle detection operation is started (FIG. 18, block 101).
[0093]
The above operation is an operation for detecting an angle using an image projected by the original image projection function of the projector 2, and the passive line type distance measuring devices 3 and 4 are used for adjustment in this way. There is no need for a dedicated projector for projecting a contrast image.
[0094]
Subsequently, the control circuit 5 sets the measurement number j of the tilt angle to the initial value (“1”) in the EEPROM (memory unit 10) (block 102), and the initial value (“1”) of the measurement number i of the distance. ) Is set (block 103), and the automatic focus adjustment integrated circuit is controlled (block 104) before operating the distance measuring function and the angle detecting function of the imaging units 31 and 41 of the passive line-type distance measuring devices 3 and 4. ) By measuring the distances to a plurality of positions in the horizontal plane and the vertical plane on the screen 1 so that the inclination angle of the screen 1 with respect to the projector 2 in the horizontal plane and the vertical plane can be easily detected. Focus the image. As described above, the angle detection operation start (block 101) can be performed at any time during the operation of the projector 2 as well as when the projector 2 is powered on. At this time, an arbitrary image projected on the screen 1 is used for distance measurement for angle detection.
[0095]
Next, the distance measurement operation and the inclination angle detection operation will be described with reference to FIG. 3 in conjunction with FIG. 18. The imaging units 31 and 41 are operated to read data from the line sensor and perform A / D conversion (FIG. 3). 32a) (block 105). The contrast centroid of each ranging calculation area (area) 31cN (N = 1,..., 11) of the line sensor is calculated by the contrast centroid calculating section (32h in FIG. 3), and each ranging calculation area (area) 31cN ( The average value of the contrast centroids of N = 1,..., 11) is obtained by the averaging unit (32j in FIG. 3) and stored in the RAM (memory means 10) (block 106). A filter (32c in FIG. 3) for removing a DC component from the sensor data of the line sensor is processed (block 107), and thereafter, a correlation calculation (32d in FIG. 3) is performed for each of the distance measurement calculation areas 31c1 to 31c11. 32e), interpolation calculation (32f in FIG. 3), phase difference detection calculation (32g in FIG. 3), and distance measurement calculation is performed (block 108). Then, reliability determination (determination of whether the degree of coincidence obtained in the maximum correlation detection unit 32e is equal to or greater than a predetermined value by the normal reliability determination unit 32i in FIG. 3) is performed, and if this reliability determination passes, CONF_FLG1 = OK is set (109). If the data reliability determination (CONF_FLG1 = OK) is not passed in two or more ranging calculation areas (areas), the angle cannot be detected. Going to the entrance C, it is determined in FIG. 19 that the angle cannot be detected (block 123), and the process ends (block 124).
[0096]
If the data reliability is passed in two or more distance measurement calculation areas in block 110 of FIG. 18, the distance measurement results and the centroid data are stored in the RAM (memory unit 10) (block 111). Then, the calculated distance measurement results of each distance calculation calculation area (area) 31cN (N = 1,..., 11) are stored in the RAM (memory unit 10), and an average value (by rounding) by a plurality of measurement times i. The average unit (32j in FIG. 3) is obtained (in units of mm) (block 111). 3 determines whether the distance measured by the first (i = 1) measurement is greater than a predetermined first set value, for example, 10 m (block 112). ). If the measured distance is larger than the predetermined first set value (10 m), a predetermined number of DATA1 (for example, “5”) stored in advance in the EEPROM (memory unit 10) as the distance measurement number i is set. Use to return to block 103 until the distance measurement count i reaches a predetermined count (DATA1 = 5) (block 113). If the measured distance is equal to or less than a predetermined first set value (10 m), the distance measurement count i is a predetermined number of times DATA2 (for example, “1” less than DATA1 previously stored in the EEPROM (memory unit 10)). 3 ”), the process returns to block 103 until the distance measurement count i reaches a predetermined count (DATA2 = 3) (block 114). In this way, the distance and contrast center-of-gravity position measurement results for each distance measurement calculation area 31cN (N = 1,..., 11) and the distance measurement distance are larger than the first set value (10 m). Or the average value of the distance measurement results obtained by the number of times of measurement i (for example, DATA1 = 5 or DATA2 = 3) according to the following is obtained by the averaging unit (32j in FIG. 3), and the RAM (memory unit) 10). Instead of obtaining the average value of the distance measurement results based on the number of measurements i in block 111, the median value excluding the maximum value and the minimum value of the distance measurement result or the average value excluding the maximum value and the minimum value may be obtained. Good. And it repeats until it reaches | attains the frequency | count i of measurement (for example, DATA1 = 5 or DATA2 = 3) memorize | stored in EEPROM (memory part 10). When the number of times of measurement i is reached, the operation moves from the outlet A to the inlet A in FIG.
[0097]
Next, a description will be given with reference to FIG. The number of measurements i (DATA1 = 5 or DATA2 =), which is selected by the averaging unit (32j in FIG. 3) where the size of the distance measurement result is larger than the first set value (for example, 10 m) or the following: 3) The mutual reliability of the distance measurement value and the contrast centroid measurement value of each distance measurement calculation area 31cN (N = 1,..., 11) averaged in 3) (significantly inconsistent with the measurement results of the front and rear distance calculation calculation areas). The validity of whether or not (block 115 and block 116). If the determination result of the mutual reliability of the distance measurement result is unacceptable, it is determined that the angle cannot be detected (block 123), and the process ends (block 124). If the measurement results pass the mutual reliability and determination processing, smoothing processing (because the measurement target is a screen plane is averaged with the measurement results of the front and rear ranging calculation areas to reduce variation) ( Block 117).
[0098]
Further, as described above, an angle calculation is performed by the least square method to determine a relative tilt angle of the screen with respect to the projector (block 118). Then, the obtained inclination angle is stored in the RAM (memory unit 10), and an average value of the inclination angles is obtained from the number of inclination angle measurements j (block 119). Then, the measurement number adjusting means 55 in FIG. 3 determines whether the inclination angle obtained by the first (j = 1) measurement is larger than a predetermined first set value, for example, 15 degrees (see FIG. 3). Block 120). If the tilt angle is larger than a predetermined second set value, the tilt angle measurement count j is set to a predetermined count of DATA3 (for example, “5”) stored in advance in the EEPROM (memory unit 10). (Block 121). If the tilt angle is equal to or smaller than a predetermined second set value, the predetermined number of times DATA4 (for example, “3”) in which the tilt angle measurement number j is smaller than DATA3 stored in advance in the EEPROM (memory unit 10). (Block 122). In this way, the tilt angle obtained by the first measurement (j = 1) is larger than the second set value (for example, 15 degrees) or the number of times of measurement j (for example, DATA3 = 5 or Until reaching DATA4 = 3), it returns to the block 102 through the exit B through the entrance B in FIG. 18, and the measurement of the distance and the calculation of the inclination angle are repeated. If a predetermined tilt angle measurement count j (eg, DATA3 = 5 or DATA4 = 3) has been reached, the angle detection operation ends (block 124). Instead of obtaining the average value of the inclination angles by a plurality of measurement times j in block 119, the median value excluding the maximum value and the minimum value of the obtained inclination angle or the average value excluding the maximum value and the minimum value is obtained. You may ask for it.
[0099]
As described above, the angle detection device according to the present invention increases the number of measurement results when the first distance measurement result is larger than the first set value and increases the number of measurements compared to the case of the first set value or less. The average error or the median value excluding the maximum value and the minimum value or the average value excluding the maximum value and the minimum value is obtained to reduce the measurement error of the distance measurement result. When the distance measurement result is less than or equal to the first set value, the measurement error is relatively small, so the number of measurements is relatively small, and high-speed distance measurement operation is performed. The distance measurement result based on the triangulation method has a measurement error that increases as the distance increases.Therefore, by increasing the number of measurements and averaging, the influence of the measurement error is minimized and a highly accurate distance measurement result is obtained. On the other hand, since the measurement error is relatively small at short distances, the number of measurements is reduced to speed up the distance measurement operation.
[0100]
The angle detection apparatus according to the present invention further includes the number of times of measurement of the distance and the inclination angle when the inclination angle obtained from the first distance measurement result is larger than the second set value, compared to the case where the angle is less than the second set value. By increasing the number of measurement calculations, the average value of the calculated tilt angle or the median value excluding the maximum and minimum values or the average value excluding the maximum and minimum values can be reduced. Like to do. When the tilt angle is equal to or smaller than the second set value, the measurement error of the tilt angle is relatively small, so that the number of times of measurement is relatively small and the tilt angle is detected at high speed. This is because if the screen tilt angle is large, the focus adjustment of the image on the screen cannot be performed and the image becomes blurred, so that the influence of measurement error is increased as much as possible to reduce the influence of measurement error so that highly accurate angle detection can be obtained. On the other hand, since the measurement error is relatively small at a short distance, the number of measurements is reduced to speed up the angle detection.
[0101]
If the angle detection device of the present invention described above is used in a projector, when the distance measurement result is large, the measurement error is relatively large, so that the accuracy of the distance measurement result is increased by increasing the number of distance measurement, and is also required. If the tilt angle is large, the measurement error due to the blurring of the image due to the defocusing of the image projected on the screen is large, so the accuracy of the distance measurement result obtained by increasing the number of distance measurements is increased and the tilt obtained based on it. Increases the accuracy of the angle. As a result, the trapezoidal distortion of the image projected on the screen can be corrected accurately and at high speed. In the above-described embodiment, a pair of line-type distance measuring devices in the horizontal direction and the vertical direction are used. However, it is not necessary to arrange them in a perpendicular relationship, and only one line-type distance measuring device is used. Good. Further, although the screen plane is used as the measurement object, the angle detection apparatus of the present invention can be applied to any planar object measurement object without being limited to the screen. For example, the planar object to be measured may be a workpiece to be processed by a machine tool, and the workpiece and the processing tool are relatively positioned so that the processing tool is opposed to the workpiece. The angle detector of the present invention can also be applied to detect the tilt angle.
[0102]
Furthermore, the least square method has been described as a method of approximating a straight line representing the correlation (distribution) of a plurality of measurement points according to the above-described embodiment of the present invention. However, the method is not limited to the least square method, and other approximations are also possible. The inclination angle may be obtained by approximating a straight line representing the correlation (distribution) of a plurality of measurement points using a method. In the present embodiment described above, the method of obtaining the inclination angle θ1 described with reference to FIG. 8 or FIG. 13 can also be used.
[0103]
【The invention's effect】
According to the present invention described in claims 1 to 3 of the present invention, it is possible to achieve an angle detection device capable of detecting an angle accurately and at high speed.
[0104]
According to the present invention described in claim 4, it is possible to achieve an angle detection device capable of automatically and accurately detecting the tilt angle of the projected screen with respect to the projector.
[0105]
According to the present invention described in claim 5, it is possible to achieve a projector capable of automatically and accurately correcting trapezoidal distortion of an image caused by a relative tilt angle between the projector and the screen.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing a configuration of a projector having an angle detection device according to one embodiment of the present invention.
FIG. 2 is a schematic front view of the projector shown in FIG.
FIG. 3 is a functional block diagram of an angle detection device according to one embodiment of the present invention.
FIG. 4 is a diagram for explaining a distance measuring operation of a distance measuring device included in the angle detecting device according to one embodiment of the present invention.
FIG. 5 is another diagram illustrating a distance measurement operation of the distance measuring device included in the angle detection device according to the embodiment of the present invention.
FIG. 6 is a block diagram showing an outline of a pair of line sensors of the distance measuring device included in the angle detection device according to one embodiment of the present invention.
FIG. 7 is another diagram illustrating distance measurement at a plurality of positions by the distance measuring device included in the angle detection device according to one embodiment of the present invention.
FIG. 8 is a diagram illustrating an angle detection method by a distance measuring device included in the angle detection device according to one embodiment of the present invention.
FIG. 9 is another diagram for explaining the angle detection method of FIG. 8;
FIG. 10 is another diagram for explaining the angle detection method of FIG. 8;
FIG. 11 is another diagram for explaining the angle detection method of FIG. 8;
FIG. 12 is another diagram illustrating a method for obtaining the contrast gravity center position of the distance measurement calculation area of the distance measuring device included in the angle detection device according to the embodiment of the present invention.
FIG. 13 is another diagram for explaining an angle detection method by the distance measuring device included in the angle detection device according to one embodiment of the present invention;
FIG. 14 is another diagram illustrating an angle detection method based on distance measurement results at a plurality of positions by a distance measurement device included in the angle detection device according to one embodiment of the present invention.
FIG. 15A is a graph showing distance measurement results at a plurality of positions by a distance measuring device included in the angle detection device and an angle calculation result based on them.
FIG. 15B is a graph for explaining a method of approximating a straight line representing a mutual relationship (distribution) of distance measurement results at a plurality of positions by a distance measuring device included in the angle detection device by the least square method according to the present invention.
FIG. 16 is a schematic diagram schematically showing a configuration of a distance measurement calculation area of a line sensor of a distance measuring device included in an angle detection device according to one embodiment of the present invention.
FIG. 17 is a diagram illustrating a method for obtaining a representative value of a distance measurement result and a representative value of a contrast centroid according to an embodiment of the present invention.
FIG. 18 is a flowchart showing the operation of the angle detection device according to one embodiment of the present invention.
FIG. 19 is a flowchart showing the operation of the angle detection device according to one embodiment of the present invention connected to the flowchart of FIG. 18;
[Explanation of symbols]
1 screen
1A to 1G measurement position
2 Projector
3 distance measuring device
4 ranging device
5 Control circuit
31 Imaging unit
31a lens
31b lens
31c line sensor
31d line sensor
31c1 to 31c11 Distance calculation area
32 Calculation unit
51 Mutual reliability judgment unit
52 Average value calculator
53 Angle calculator
55 Measuring frequency adjustment means
k Baseline length
θ1 Inclination angle that the screen 1 is in the baseline length k direction in the horizontal plane

Claims (5)

A pair of lenses arranged on the same plane and spaced apart by a base line length, and a measurement object is arranged through the pair of lenses arranged to extend in the base line length direction by a predetermined distance from the pair of lenses. A pair of line sensors to be imaged thereon, and outputs from the pair of line sensors and a plurality of different distance measuring directions on the plane including the baseline length and the line sensor based on the measurement output A passive line-type distance measuring device comprising a calculation unit for calculating the distance to a plurality of different positions on the measurement object in
An inclination angle calculation unit that calculates an inclination angle of the measurement target with respect to the same plane on a plane including the baseline length and the line sensor, using at least two calculation results of the distance calculated by the calculation unit;
An angle detection apparatus comprising: a measurement number adjusting unit configured to adjust the number of times of the measurement based on a distance calculated by the calculation unit or an inclination angle calculated by the inclination angle calculation unit. When the distance calculated by the calculation unit is greater than a first set value, or when the tilt angle calculated by the tilt angle calculation unit is greater than a second set value, The angle detection device according to claim 1, wherein the number of times of the measurement is increased as compared with the case of the first or second set value or less. A passive line-type distance measuring device that measures the distance to a plurality of different measurement points arranged substantially linearly on the measurement object;
An inclination angle calculation unit for calculating an inclination angle of the object to be measured with respect to the distance measuring device based on at least two measured distances;
When the distance exceeds the first set value or when the tilt angle exceeds the second set value, the number of times of the distance measurement by the passive line-type measurement distance device is set to the first set value or the first set value, respectively. An angle detection device comprising: a measurement frequency adjusting means for increasing the number of times compared to a case where the set value is 2 or less. The angle detection device according to claim 1, wherein the measurement target is a screen on which an image is projected. An projector for projecting an image onto a screen, wherein the angle detection device according to claim 4 and an image distortion correction unit that corrects distortion of the image on the screen based on an inclination angle calculated by the angle detection device, Including a projector.

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