JP3791068B2 - Predictive distance measuring device and photographing device - Google Patents

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となる。先に定めたＸＹ座標系の「Ｘ切片」は、ｔ０時の被写体位置である（Ｒ０，０）である。
上記演算により、撮影装置に対する被写体の移動経路が求められる。
【００２５】
時刻ｔ１から更にｄｔ時間後の時刻ｔ２の被写体位置（座標）は、

になる。このときの被写体までの距離は、
Ｒ２＝ＳＱＲＴ｛（２・Ｒ１・ｃｏｓθ１−Ｒ０）² ＋（２・Ｒ１・ｓｉｎθ１）² ｝ （ただし、ＳＱＲＴ：平方根を表す） ・・・（式１−５）
となる。
ここで、被写体の移動経路を考慮せず、時刻ｔ０及びｔ１における撮影距離Ｒ０、Ｒ１のみの情報から時刻ｔ２における撮影距離を算出した場合に、この算出値をＲ２’とすれば、
Ｒ２’＝２・Ｒ１−Ｒ０ ・・・（式１−６）
になり、先のθ１＝０の時にはＲ２＝Ｒ２’となるが、それ以外では異なる値となる。
【００２６】
以下、時刻ｔ０からｎ×ｄｔ時間後の時刻ｔｎにおける被写体位置（座標）は、
（Ｘｎ，Ｙｎ）＝（ｎ・Ｒ１・ｃｏｓθ１−（ｎ−１）・Ｒ０，ｎ・Ｒ１・ｓｉｎθ１） ・・・（式１−７）
になり、このときの被写体までの距離は、
Ｒｎ＝ＳＱＲＴ［｛ｎ・Ｒ１・ｃｏｓθ１−（ｎ−１）・Ｒ０｝² ＋（ｎ・Ｒ１・ｓｉｎθ１）² ］ ・・・（式１−８）
となる。
【００２７】
ここで、先の図２の説明に戻る。Ｓ１７０において、Ｓ１６０で算出した被写体の移動経路、移動速度、ある時刻に予想される被写体位置と、被写体までの距離に基づいて、レンズ合焦駆動部５を制御して撮影レンズ２の合焦駆動を行わせる。
Ｓ１７０において、合焦駆動をさせた後に、Ｓ１１０に戻り、再びレリーズ全押しスイッチ（不図示）がＯＮか否かを判断して、撮影者による露光動作開始指示の有無を判定する。以下、露光動作に移行しない場合には、先に説明したＳ１２０以下のフローを繰り返す。
【００２８】
以上のように、第１実施形態によれば、被写体までの測距情報及び角度位置情報を用いて、移動する被写体の正確な距離変化を演算により求めることができ、その演算の結果に基づいた正確な合焦駆動を行える。これらによって、特に、斜め方向に移動する被写体の撮影に対して良好な画像を得ることができる。
【００２９】
（第２実施形態）
図４は、本発明を適用したカメラの第２実施形態の構成を示す図である。
図４に示した一眼レフカメラは、図１で説明したカメラの測距部４の代わりに撮影レンズ２を通して得られる被写体像の焦点位置を検出する焦点検出部８を有している。
カメラＣＰＵユニット１，撮影レンズ２，ブレ検出部３，レンズ合焦駆動部５，レンズ位置検出部６は、図１の実施形態と同じであるので、以下、図１と異なる部分のみ説明する。
【００３０】
ミラー部７は、撮影レンズ２を透過した被写体光をファインダスクリーンと焦点検出部８（後述）に、それぞれ導くミラーであり、半透ミラーであるメインミラーと、反射ミラーであるサブミラーとから構成されている。
【００３１】
焦点検出部８は、撮影レンズ２を通して得られる被写体像の焦点位置を検出する部分であり、ここでは、分割瞳方式の焦点検出装置が用いられている。
【００３２】
レンズ位置検出部６は、レンズ合焦駆動部５によって駆動させられた撮影レンズ２の光軸方向の位置を検出する。カメラＣＰＵユニット１は、その検出結果に基づいて、測距部４によって検出した被写体までの撮影距離に対して、撮影レンズ２の位置が適正であるか否かをモニタする。
【００３３】
ここで、本実施形態のカメラＣＰＵユニット１は、焦点検出部８から得られる焦点位置情報及びレンズ位置検出部６から得られるレンズ位置情報から、被写体までの距離を演算によって求める。この演算は、レンズの焦点距離及び焦点位置が分かれば、幾何光学的に簡単に行なうことができる。
【００３４】
また、撮影レンズ２がズームレンズであって、撮影時のレンズの焦点距離が変化する可能性がある場合は、レンズ位置検出部６に、ズーム位置検出部（不図示）をさらに追加して、先の図３や数式の箇所で説明した時刻ｔ０、ｔ１等の焦点検出部８による焦点位置検出時刻における、撮影レンズ２の実焦点距離の情報を得られるようにすればよい。このようにすれば、カメラＣＰＵユニット１は、各時刻における被写体までの距離を演算することが可能となる。
【００３５】
第２実施形態によれば、被写体までの距離を焦点検出出力及び撮影レンズの位置情報によって得られるようにしたので、焦点検出部を有するＡＦ一眼レフカメラにも、本発明を容易に適用できる。
【００３６】
（第３実施形態）
図５は、第３実施形態に係るカメラの動作を説明するフロー図である。
なお、第３実施形態は、第１実施形態の構成を示す図１と同様に表わすことができるので、図示を省略して、図１を参照して説明する。
カメラＣＰＵユニット１は、カメラの電源スイッチ（不図示）がＯＮしたか、又は、レリーズ半押しスイッチ（不図示）がＯＮしたことを検出して、ステップ（以下Ｓと略す）１００からカメラの一連の撮影準備動作を開始させる。
以下の説明では、各ステップは、断りの無い場合にはカメラＣＰＵユニット１で行われる。
【００３７】
Ｓ２１０において、レリーズ全押しスイッチ（不図示）がＯＮとなっているか否かを判断する。レリーズ全押しスイッチがＯＮであれば、撮影者によって露光動作開始が指示されていることになるので、Ｓ４００の露光ルーチンに進む。レリーズ全押しスイッチがＯＮでないときには、露光開始ではないので、Ｓ２２０以下に進み、合焦駆動等の撮影準備動作を続ける。
なお、Ｓ４００以下の露光ルーチンは、従来からのカメラの動作に準じるので、ここでは、説明を省略する。
【００３８】
Ｓ２２０において、測距部４に被写体までの撮影距離を検出させ、測距情報を記憶する。たとえば、時刻ｔ０において、最初に測距した被写体距離をＲ０とする。
Ｓ２３０を最初に通過するときに、つまり、先のＳ２２０で検出した測距情報が初回の測距情報であるときには、被写体までの距離変化について測定及び演算が不能であるので、本ステップでは演算を行わずに通過する。
【００３９】
次に、Ｓ２４０において、ブレ検出部３に角速度を検出させ、カメラに加えられる角速度の情報を記憶する。例えば、時刻ｔ０’（ｔ０と同時であってもよいし、違っていてもよい）において、最初に検出した角速度をω０とする。
Ｓ２５０からＳ２８０までの判定及び補正のステップも、Ｓ２３０と同様に、最初に通過するときは、角速度の変化について判定不能であるので、これらのステップでは、演算を行わずに通過する。
【００４０】
Ｓ２９０において、先のＳ２２０で得られた被写体までの距離情報に基づいて、レンズ合焦駆動部５の合焦動制御を行って、撮影レンズ２の焦点位置を調節する。
【００４１】
次に、２回目以降のルーチンについて説明する。
Ｓ２１０、Ｓ２２０を実行し、Ｓ２３０では、これまでに得られた測距情報に基づいて、近づいてくる被写体までの距離変化の速度を算出する。２回目以降のルーチンにおいて、Ｓ２３０で行われる演算は、以下の式による。
１つ前のルーチンにおいて、時刻ｔ０で測距した被写体距離をＲ０とする。今回のルーチンにおいて、時刻ｔ１で測距した被写体距離をＲ１とする。前回の測距から今回の測距までの時間をｄｔとすれば、被写体までの距離変化の速度ｄＲ／ｄｔは、次式のようになる。
ｄＲ／ｄｔ＝（Ｒ１−Ｒ０）／ｄｔ ・・・（式２−１）
【００４２】
以上のように得られた距離変化の速度によって、今後の距離変化の予測が可能となる。例えば、時刻ｔ１よりも更にｄｔ時間後の時刻ｔ２での被写体距離（推定値）Ｒ２＾は 、以下の値として算出される。
Ｒ２＾＝Ｒ１＋ｄＲ・ｄｔ＝２・Ｒ１−Ｒ０ ・・・（式２−２）
【００４３】
後のＳ２９０で行う合焦駆動制御は、上記結果に基づいて、撮影レンズ２の焦点位置調節を、レンズ合焦駆動部５に実行させればよいが、更に以下に述べるＳ２５０からＳ２８０までの状況の判定及び補正を行うと、レンズ合焦駆動部５による合焦駆動の精度が向上する。
【００４４】
Ｓ２５０からＳ２８０における判定及び補正について、以下に述べる。
Ｓ２４０において、一つ前のルーチンで時刻ｔ０’において検出した角速度情報をω０とする。また、今回のルーチンで時刻ｔ１’（先のｔ１と同時であってもよいし、違っていてもよい）において検出した角速度情報をω１とする。
【００４５】
Ｓ２５０において、上記ω０とω１の大小の比較を行う。ω０＜ω１であれば、Ｓ２６０に進む。そうでなければ、Ｓ２６０をジャンプしてＳ２７０に進む。ω０＜ω１である場合は、移動する被写体を撮影領域に捉え続けようとするときに、カメラに加えられる角速度が、増加傾向にあるときである。
【００４６】
図６は、第２実施形態に係るカメラが等速で移動する被写体までの距離変化と、被写体を撮影領域に捉え続けようとするときに、カメラに加えられる角速度の変化を説明する図である。
時刻ｔ０’（ここでは、簡単のために、ｔ０’＝ｔ０とする）に、角速度検出を行い、角速度検出値ω０を得たとする。
このときの移動被写体の移動速度をＶとすれば、ω０は以下の式で表すことができる。
ω０＝（Ｖ・ｓｉｎθ０）／Ｒ０ ・・・（式２−３）
【００４７】
次に、時刻ｔ１’（簡単のために、ｔ１’＝ｔ１とする）に、角速度検出を行い、角速度検出値ω１を得たとする。
移動被写体は、同じ移動速度Ｖで移動しており、ω１は以下の式で表すことができる。
ω１＝（Ｖ・ｓｉｎθ１）／Ｒ１ ・・・（式２−４）
【００４８】
ここで、ω０とω１の大小を検討してみる。被写体が近づいてくる状況であるから、θは０≦θ≦π／２（ｒａｄ）である。
図６から、ｓｉｎθ０＜ｓｉｎθ１、であることが分かる。また、Ｒ０＞Ｒ１であることが分かる。よって、先の（式２−３）及び（式２−４）の右辺の分子及び分母の大小関係から、図６の状況では、ω０＜ω１であることが分かる。
【００４９】
以上の大小関係から、等速で移動する被写体が斜めに近づいてくるときには、ω０＜ω１が成り立つ。また、上記で説明した（式２−３）及び（式２−４）の関係から、被写体が最接近するまでは角速度が増加傾向であり、それとは逆に、被写体が最接近位置を通り過ぎて、遠ざかっていくときには、角速度が減少傾向であることが分ける。
【００５０】
次に、Ｓ２６０で行うプラス補正に関して説明する。
Ｓ２３０で演算される距離変化速度は、図６に示すような等速で移動する被写体が斜めに近づいてくるときには、誤差を生じる。
時刻ｔ０に測距を行い、測距値Ｒ０を得たとする。図６に示すように、このときの被写体位置（座標）を、以下のようにする。
（Ｘ０，Ｙ０）＝（Ｒ０，０） ・・・（式２−５）
【００５１】
つまり、撮影位置を原点とするＸＹ座標系を設定し、このＸ軸上Ｒ０の距離の地点としてやる。
また、被写体の移動速度をＶとし、そのＸ軸方向成分をＶｘ、Ｙ軸方向成分をＶｙとする。被写体の移動方向と上記において規定したＸ軸との成す角度をθ０とする。
つぎに、ｄｔ時間後の時刻ｔ１に測距を行い、測距値Ｒ１を得たとする。この間、被写体は（Ｒ０，０）の位置から（−Ｖｘ・ｄｔ，Ｖｙ・ｄｔ）だけ移動する。Ｒ１は以下の値になる。
Ｒ１＝ＳＱＲＴ｛（Ｒ０−Ｖｘ・ｄｔ）² ＋（Ｖｙ・ｄｔ）² ｝ （ただし、ＳＱＲＴ：平方根を表す） ・・・（式２−６）
【００５２】
よって、更にｄｔ時間後の時刻ｔ２における被写体までの距離の推定値Ｒ２＾は、以下の式２−７になる。
Ｒ２＾＝Ｒ１＋ｄＲ＝２・Ｒ１−Ｒ０ ・・・（式２−７）＝（式２−２）
例えば、時刻ｔ０における被写体位置（Ｘ０，Ｙ０）＝（２０，０）、Ｖｘ・ｄｔ＝４、Ｖｙ・ｄｔ＝３としてみると、

【００５３】
ところが、被写体の時刻ｔ２における真の位置は、
（Ｒ０−２・Ｖｘ・ｄｔ，２・Ｖｙ・ｄｔ）の位置であり、真の被写体までの距離Ｒ２は、以下の値になる。

【００５４】
以上のように、（式２−７）＝（式２−２）の演算による被写体までの距離の推定値に比較して、等速で移動する被写体が斜めに近づいてくるときには、予想よりも距離の変化速度が小さく、所定時間後の距離が予想よりも遠くなってしまう。つまり、距離変化速度を小さく見積り直してやらなくてはいけないことになる。
【００５５】
先の図５の説明に戻る。Ｓ２５０で上記ω０とω１の大小の比較を行う。ω０＜ω１であればＳ２６０に進む。そうでなければＳ２７０に進む。
Ｓ２６０では、移動する被写体が斜めに近づいてくる状況に応じて、Ｓ２３０で算出された距離変化速度に縮小補正（距離変化速度の絶対値が小さくなるように補正）を行う。
補正係数に関しては、被写体の移動速度や斜めに近づいてくる移動経路の状況により異なるが、カメラが実際に使用される状況の頻度を考慮した実験により、角速度変化に応じていくつかの補正係数をカメラＣＰＵユニット１内の記憶部分に記憶させておけばよい。
【００５６】
次に、Ｓ２７０でω０＞ω１であるか否かの判定を行う。ω０＞ω１であればＳ２８０に進む。ω０＞ω１でなければ、Ｓ２８０をジャンプしてＳ２９０に進む。
Ｓ２８０では、移動する被写体が斜めに遠ざかる状況に応じて、Ｓ２３０で算出された距離変化速度に拡大補正（距離変化速度の絶対値が大きくなるように補正）を行う。
補正係数に関しては、被写体の移動速度や斜めに遠ざかる移動経路の状況により異なるが、カメラが実際に使用される状況の頻度を考慮した実験により、Ｓ２６０と同様に、角速度変化に応じていくつかの補正係数をカメラＣＰＵユニット１内の記憶部分に記憶させておけばよい。
【００５７】
Ｓ２９０では、先のＳ２３０で得られた被写体までの距離変化速度演算結果、又は、その演算結果に対して、Ｓ２６０又はＳ２８０で行われた補正に基づいて、レンズ合焦駆動部５の合焦動制御を行って、撮影レンズ２の焦点位置を調節する。
Ｓ２９０の後に、Ｓ２１０に戻りレリーズ全押しスイッチ（不図示）がＯＮか否かを判断して、撮影者による露光動作開始指示の有無を判定する。以下、露光動作に移行しない場合には、先に説明したＳ２２０以下のフローを繰り返す。
【００５８】
カメラに対して斜めに等速で接近してくる被写体を撮影するとき、カメラに加えられる角速度は最初は小さいが、だんだんと大きくなっていき、最接近点で最大となる。そして カメラから被写体が遠ざかると共に、再び角速度は小さくなる。
一方、上記被写体とカメラとの相対的な距離変化を考えると、最初は被写体の移動速度とほぼ同じ速度で距離が縮まるが、被写体が近づいてくるとカメラに向かって斜め方向に移動することになり、お互いの距離変化は、被写体の移動速度よりも小さくなる。最接近点では、被写体は、カメラに対して横方向の移動となるので、距離変化はわずかでしかない。再び被写体がカメラから遠ざかるときには、近づく場合の逆となる。
【００５９】
以上の動作により、移動する被写体に対する測距情報、及び、被写体を撮影領域に捉え続けようとするときにカメラに加えられる角速度情報を用いて、移動被写体の距離変化速度を演算により求めることがでる。つまり、本発明においては、被写体までの距離とカメラに加えられる角速度の変化を検出し、それらの検出信号からカメラと移動被写体間の相対的な距離変化を補正して算出するようにしたので、簡単な演算で撮影距離の変化を予測できるようになった。
そして、その結果に基づいた正確な合焦駆動が行えるので、特に、斜め方向に移動する被写体の撮影に対して良好な画像を得ることができるようになる。
【００６０】
なお、図５で説明した例では、Ｓ２５０及びＳ２７０の判断をω０＜ω１若しくはω０＞ω１としたが、これをω０−ω１＜Ｃ１若しくはω０−ω１＞Ｃ２のようにして、所定の不感領域を持たせてもよい（Ｃ１、Ｃ２は所定の定数）。
これは、補正が頻繁に掛かり過ぎて、合焦駆動制御が不安定になるのを防ぐ効果があるからである。
【００６１】
また、Ｒ０、Ｒ１を検出する時刻ｔ０、ｔ１と、ω０、ω１を検出する時刻ｔ１’、ｔ２’は、それぞれ同時刻の必要がないと記したが、これは角速度については増加傾向なのか若しくは減少傾向なのかを判定するだけであるので、必ずしも測距するタイミングと同一の必要がないためである。
また、以上の例では、被写体までの距離変化速度を現在及び過去の２つの測距情報から直線的な係数を求める形としたが、この方法に限らない。現在及び過去の３つ以上の測距情報を用いて、２次以上の回帰曲線を求める演算方式であってもよい。
【００６２】
また、角速度の変化を現在及び過去の角速度情報から求めたが、これも角加速度センサを用いて角加速度情報を得るようにしてもよい。もちろん、２個以上の加速度センサを組み合わせて用いて、それらの加速度センサの差から角加速度を算出するようにしてもよい。
【００６３】
（第４実施形態）
第４実施形態は、図４の実施形態と同様に表される構成において、第３実施形態の手法を適用したものであるので、その構成を図４を参照して説明する。
第４実施形態の一眼レフカメラは、カメラＣＰＵユニット１，撮影レンズ２，ブレ検出部３，レンズ合焦駆動部５，レンズ位置検出部６に加えて、ミラー部７、及び、撮影レンズ２を通して得られる被写体像の焦点位置を検出する焦点検出部８を有している。
【００６４】
ミラー部７は、撮影レンズ２を透過した被写体光をファインダスクリーンと焦点検出部８に、それぞれ導くミラーであり、半透ミラーであるメインミラーと、反射ミラーであるサブミラーとから構成されている。
【００６５】
焦点検出部８は、撮影レンズ２を通して得られる被写体像の焦点位置を検出する部分であり、ここでは、分割瞳方式の焦点検出装置が用いられている。
【００６６】
レンズ位置検出部６は、レンズ合焦駆動部５によって駆動させられた撮影レンズ２の光軸方向の位置を検出する。カメラＣＰＵユニット１は、その検出結果に基づいて、測距部４によって検出した被写体までの撮影距離に対して、撮影レンズ２の位置が適正であるか否かをモニタする。
【００６７】
ここで、本実施形態のカメラＣＰＵユニット１は、焦点検出部８から得られる焦点位置情報及びレンズ位置検出部６から得られるレンズ位置情報から、被写体までの距離を演算によって求める。この演算は、レンズの焦点距離及び焦点位置が分かれば、幾何光学的に簡単に行なうことができる。
【００６８】
また、撮影レンズ２がズームレンズであって、撮影時のレンズの焦点距離が変化する可能性がある場合は、レンズ位置検出部６に、ズーム位置検出部（不図示）をさらに追加して、先の図６や数式の箇所で説明した時刻ｔ０、ｔ１等の焦点検出部８による焦点位置検出時刻における、撮影レンズ２の実焦点距離の情報を得られるようにすればよい。このようにすれば、カメラＣＰＵユニット１は、各時刻における被写体までの距離を演算することが可能となる。
【００６９】
（第５実施形態）
第５実施形態のカメラは、第４実施形態で説明したカメラにおいて、レンズ位置検出部６の機能の一部であるズーム位置検出部（不図示）等を省略したものである。
この第５実施形態のように、レンズ位置検出部６の一部機能を省略すると、カメラＣＰＵユニット１は、焦点位置情報から被写体までの距離を換算できなくなるが、現在の焦点位置と正規の合焦位置との差は分かるので、レンズ合焦駆動部５の駆動制御は、可能である。
【００７０】
図７は、本発明が適用されるカメラの第５実施形態で行われる動作を説明するフロー図である。図５と同様の部分は、説明を省略する。
カメラＣＰＵユニット１は、Ｓ３００からカメラの一連の撮影準備動作を開始させる。Ｓ３１０でレリーズ全押しスイッチ（不図示）がＯＮとなっているか否かを判断し、レリーズ全押しスイッチがＯＮであれば、Ｓ４００の露光ルーチンに進み、ＯＮでないときには、Ｓ３２０以下に進む。
【００７１】
Ｓ３２０において、焦点検出部８に焦点位置を検出させ、焦点位置情報を記憶する。例えば、時刻ｔ０において最初に検出した焦点位置をＺ０とする。以下、Ｓ３３０及びＳ３５０からＳ３８０を最初に通過するときは、先の第３実施形態で説明した場合と同じく、各処理を行わずに通過する。
【００７２】
Ｓ３４０では、ブレ検出部３に角速度を検出させ、カメラに加えられる角速度の情報を記憶する。例えば、時刻ｔ０’（ｔ０と同時であってもよいし、違っていてもよい）において、最初に検出した角速度をω０とする。
Ｓ３９０では、先のＳ３２０で得られた焦点位置情報に基づいて、レンズ合焦駆動部５の合焦動制御を行い、撮影レンズ２の焦点位置を調節する。
【００７３】
次に、２回目以降のルーチンについて説明する。
２回目以降のＳ３３０では、これまでに得られた情報に基づいて、被写体像の焦点位置変化速度を算出する。１つ前のルーチンで、時刻ｔ０において検出した焦点位置をＺ０とする。今回のルーチンで、時刻ｔ１において検出した焦点位置をＺ１とする。前回と今回の時間間隔をｄｔとすれば、焦点位置変化の速度ｄＺ／ｄｔは、下記のようになる。
ｄＺ／ｄｔ＝（Ｚ１−Ｚ０）／ｄｔ ・・・（式２−１２）
【００７４】
以上のように、被写体像の焦点位置変化速度が算出でき、今後の焦点位置の予測が可能となる。例えば、時刻ｔ１よりも更にｄｔ時間後の時刻ｔ２での焦点位置（推定値）Ｚ２＾は、以下の値として算出される。
Ｚ２＾＝Ｚ１＋ｄＺ・ｄｔ＝２・Ｚ１−Ｚ０ ・・・（式２−１３）
前回検出の焦点位置Ｚ０に基づいて、既に撮影レンズ２の焦点位置がレンズ合焦駆動部５によって合焦駆動されている場合には、既に駆動された量（−Ｚ０）を考慮する必要があるので、焦点位置の変化の速度ｄＺｃ／ｄｔは、下記の式になる。

【００７５】
Ｓ３４０では、時刻ｔ１’（ｔ１と同時であってもよいし、違っていてもよい）において、角速度をω１を検出して記憶する。
１つ前のルーチンで、時刻ｔ０’において検出した角速度情報はω０であり、今回のルーチンで検出した角速度情報はω１である。
【００７６】
Ｓ３５０からＳ３８０における判定及び補正についても、先の第３実施形態と同様である。等速で移動する被写体が斜めに近づいてくる場合に、被写体が最接近するまではω０＜ω１が成り立ち、角速度が増加傾向であり、それとは逆に、被写体が最接近位置を通り過ぎ遠ざかっていくときには、ω０＞ω１となり、角速度が減少傾向となる。このため、先ずＳ３５０でω０＜ω１の判定を行う。ω０＜ω１であればＳ３６０に進む。そうでなければ、Ｓ３７０に進む。
【００７７】
Ｓ３６０では、先の第３実施形態のＳ２６０で説明したのと同様に、焦点位置変化速度に対して補正を行う。Ｓ３６０に至る状況は、移動する被写体が斜めに近づいてくる場合であり、第３実施形態で説明したように、被写体は予想よりも近づかない。つまり、被写体までの距離変化速度を小さく補正し直さなければいけない。これは、焦点位置変化速度についても、位置変化速度の縮小補正（位置変化速度の絶対値が小さくなるように補正）をする必要がある。よって、Ｓ３６０ではＳ３３０で算出された焦点位置変化速度に対して、縮小補正を行う。補正係数に関しては、被写体の移動速度や斜めに近づいてくる移動経路の状況により異なるが、カメラが実際に使用される状況の頻度を考慮した実験により、角速度変化に応じて、いくつかの補正係数をカメラＣＰＵユニット１内の記憶部分に記憶させておけばよい。
【００７８】
次に、Ｓ３７０で今度はω０＞ω１か否かの判定を行う。ω０＞ω１である場合には、Ｓ３８０に進む。そうでない場合には、Ｓ３９０に進む。
Ｓ３８０では、移動する被写体が斜めに遠ざかる状況に応じて、Ｓ３３０で算出された焦点位置変化速度に拡大補正（位置変化速度の絶対値が大きくなるように補正）を行う。
補正係数に関しては、被写体の移動速度や斜めに遠ざかる移動経路の状況により異なるが、カメラが実際に使用される状況の頻度を考慮した実験により、Ｓ３６０と同様に、角速度変化に応じて、いくつかの補正係数をカメラＣＰＵユニット１内の記憶部分に記憶させておけばよい。
【００７９】
Ｓ３９０では、先のＳ３３０で得られた被写体までの焦点位置変化速度の演算結果、又は、その演算結果に対してＳ３６０又はＳ３８０で行われた補正に基づいて、レンズ合焦駆動部５の合焦動制御を行い、撮影レンズ２の焦点位置を調節する。
【００８０】
Ｓ３９０の後に、Ｓ３１０に戻りレリーズ全押しスイッチ（不図示）がＯＮか否かを判断して、撮影者による露光動作開始指示の有無を判定する。以下、露光動作に移行しない場合には、先に説明したＳ３２０以下のフローを繰り返す。
【００８１】
以上の動作により、被写体の焦点位置情報、及び、被写体を撮影領域に捉え続けようとするときにカメラに加えられる角速度情報を用いて、被写体像の焦点位置変化速度を演算により求めることができ、その結果に基づいた正確な合焦駆動が行える。これらによって、特に、斜め方向に移動する被写体の撮影に対して、良好な画像を得ることができるようになる。
【００８２】
なお、図７で説明した例では、Ｓ３５０及びＳ３７０の判断をω０＜ω１若しくはω０＞ω１としたが、これをω０−ω１＜Ｃ３若しくはω０−ω１＞Ｃ４のようにして、所定の不感領域を持たせてもよい（Ｃ３、Ｃ４は所定の定数）。
これは、補正が頻繁に掛かり過ぎて合焦駆動制御が不安定になるのを防ぐ効果があるからである。
【００８３】
また、Ｒ０、Ｒ１を検出する時刻ｔ０、ｔ１と、ω０、ω１を検出する時刻ｔ１’、ｔ２’は、それぞれ同時刻の必要がないと記したが、これは角速度については増加傾向なのか若しくは減少傾向なのかを判定するだけであるので、必ずしも測距するタイミングと同一の必要がないためである。
さらに、以上の例では、被写体像の焦点位置変化速度を現在及び過去の２つの焦点検出情報から直線的な係数を求める形としたが、この方法に限らない。現在及び過去の３つ以上の情報を用いて、２次以上の回帰曲線を求める演算方式であってもよい。
さらにまた、角速度の変化を現在及び過去の角速度情報から求めたが、これも角加速度センサを用いて角加速度情報を得るようにしてもよい。もちろん、２個以上の加速度センサを組み合わせて用いて、それらの加速度センサの差から角加速度を算出するようにしてもよい。
【００８５】
前述した実施形態では、カメラＣＰＵユニット１によって演算した被写体までの距離の変化（予測値）は、レンズ合焦駆動部５の動作制御のために用いたが、他の用途に使用することができる。例えば、前記予測値を表示する表示部を設け、所定の撮影距離にピントを合わせておき、その位置に被写体が到達する時点を予測してシャッタをきる、いわゆる置きピン撮影をする目安とするようにしてもよい。また、ストロボ撮影を行なう場合に、そのガイドナンバに応じた、撮影可能距離（ストロボ光到達距離）に、被写体が移動してすることを予測して、発光するように制御することができる。さらに、同様なシーンを同じ縮尺で撮影したい場合に、移動被写体の位置を予測して、同一地点で撮影するときに使用してもよい。
【００８６】
【発明の効果】
以上詳しく説明したように、本発明は、移動体までの距離と、移動方向（例えば、装置の向きの変化）を検出し、例えば、それらの検出信号から被写体移動経路と移動速度を算出するようにしたので、簡単な演算によって移動体までの距離の変化を正確に予測することができる。また、その予測測距値に基づいて、適切な撮影レンズの合焦駆動ができるようになったので、移動する被写体に対して、常に鮮明な画像で撮影することができるようになった。
【図面の簡単な説明】
【図１】本発明を適用したカメラの第１実施形態の構成を示す図である。
【図２】第１実施形態に係るカメラの動作を説明するフロー図である。
【図３】第１実施形態に係るカメラの移動体に対する測距値の変化を説明するための図である。
【図４】本発明を適用したカメラの第２実施形態の構成を示す図である。
【図５】第３実施形態に係るカメラの動作を説明するフロー図である。
【図６】第３実施形態に係るカメラが等速で移動する被写体までの距離変化と、被写体を撮影領域に捉え続けようとするときに、カメラに加えられる角速度の変化を説明する図である。
【図７】第５実施形態に係るカメラの動作を説明するフロー図である。
【符号の説明】
１ カメラＣＰＵユニット
２ 撮影レンズ
３ ブレ検出部
４ 測距部
５ レンズ合焦駆動部
６ レンズ位置検出部
７ ミラー部
８ 焦点検出部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a predictive distance measuring device that predicts and measures a shooting distance to a moving object, and an imaging device that applies the predicted distance measurement to AF control that can adjust the imaging state of a shooting optical system. is there.
[0002]
[Prior art]
Conventionally, the AF camera determines whether or not the subject has moved based on the past several defocus amounts from the focus detection device. Based on the focus amount, the movement of the subject is predicted and the defocus amount of the focus detection device is corrected so as to follow the movement, so that the moving subject is kept in focus. Those equipped with the predicted drive AF device are known (see, for example, JP-A-63-148218 and JP-A-3-256015).
[0003]
[Problems to be solved by the invention]
However, the above-described conventional predictive drive AF device has a problem that an error occurs in the prediction calculation because the change in the shooting distance is not constant (linear) with respect to a subject approaching from an oblique direction. there were.
[0004]
An object of the present invention is to provide a predictive distance measuring device and a photographing device capable of accurately predicting and measuring a distance change of a moving body moving in an oblique direction by a simple calculation.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention of claim 1 includes a distance measuring unit that detects a distance to a moving body, and an angle detecting unit that detects an angle or an angular velocity of a device that changes according to a moving direction of the moving body. And a prediction calculation unit that obtains a movement locus of the moving body based on the detection output of the distance measuring unit and the detection output of the angle detection unit, and predicts a change in the distance to the moving body based on the movement locus ; Is a predictive ranging apparatus including
[0007]
According to a second aspect of the present invention, in the predictive distance measuring device according to the first aspect, the distance measuring unit includes a focus detection unit that detects an imaging state of the moving body by the optical system of the device, and light of the optical system of the device. And an adjustment amount detector that detects an adjustment amount in the axial direction.
[0008]
According to a third aspect of the present invention, in the predictive distance measuring device according to the first or second aspect, the prediction calculation unit is configured to detect the moving object based on the detection output of the distance measurement unit and the detection output of the angle detection unit. A moving body speed calculation unit for calculating a moving direction and a moving speed is provided.
[0009]
According to a fourth aspect of the present invention, in the predictive distance measuring device according to any one of the first to third aspects, the angle detection unit outputs an angular velocity sensor that outputs an angular velocity signal and an output of the angular velocity sensor. And an angle calculator that integrates and calculates an angle change amount.
[0010]
According to a fifth aspect of the present invention, in the predictive distance measuring device according to any one of the first to fourth aspects, the angle detection unit is configured to change the angle in synchronization with a distance measurement timing of the distance measurement unit. An amount is calculated.
[0011]
The invention according to claim 6 is the predictive distance measuring device according to any one of claims 1 to 5 , wherein the distance measuring unit calculates distances R0 and R1 to the moving body at predetermined times t0 and t1. And the angle detection unit detects a change amount θ1 in the direction of the moving body from the predetermined time t0 to t1.
[0012]
According to a seventh aspect of the present invention, there is provided a predictive distance measuring device according to any one of the first to sixth aspects, a focus driving unit for adjusting an imaging state of an optical system of the device, and the predicted distance measuring device. based on the output, and a focusing control unit for controlling the operation of said focusing drive unit is including imaging apparatus.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a first embodiment of a camera to which the present invention is applied.
The camera CPU unit 1 is a part that controls the operation of the entire camera, such as various calculation processes and determination processes based on information from the blur detection unit 3 and the distance measurement unit 4, and the lens focusing drive unit 5. Drive control is performed. In addition, a non-volatile memory element (EEPROM, flash memory, or the like) that stores predetermined values necessary for calculation is provided.
[0014]
The photographic lens 2 is a lens group constituting a photographic optical system including a focusing optical system, a blur correction optical system, and the like. In the present embodiment, the photographic lens 2 is illustrated as a single lens for simplicity, but this is not restrictive.
The shake detection unit 3 is a part that detects camera shake, and is a pitch angular velocity sensor that detects angular velocities about the X axis in the horizontal direction of the camera (vertical direction in the drawing in the drawing) and the Y axis in the vertical direction (up and down direction in the drawing) 3a (detects an angular velocity around the X axis) and a yaw angular velocity sensor 3b (detects an angular velocity around the Y axis), and the detection output from each of the sensors 3a and 3b passes through an appropriate processing circuit such as an amplifier circuit. Later, it is output to the camera CPU unit 1.
[0015]
As the angular velocity sensors 3a and 3b, a small angular velocity sensor such as a known piezoelectric vibration gyro is preferably used. In recent years, the technological progress of a gyro sensor capable of detecting an angular velocity has been remarkable, and a small high-performance gyro sensor that can be mounted on a so-called shake correction camera or the like has been developed. By using such a gyro sensor, it is possible to detect an angle change (direction change) in the camera photographing direction, and it is possible to detect a change in the direction in which the camera is directed, that is, a change in the direction of the moving subject.
[0016]
The distance measuring unit 4 is a part that detects the shooting distance to the subject, and a triangulation optical distance measuring sensor that is generally used in a compact camera or the like is preferably used. Also, a sonic rangefinder may be used.
The lens focusing drive unit 5 is a part that drives at least a part of the photographing lens 2 in the optical axis direction and adjusts the focus state of the photographing lens 2, and is controlled by the camera CPU unit 1 for focusing driving. Here, a mechanism is used in which the cam cylinder is rotated by a DC motor and the photographing lens 2 is moved in the optical axis direction.
[0017]
The lens position detection unit 6 is a part that detects the position of the taking lens 2 driven by the lens focusing drive unit 5 in the optical axis direction, and the detection signal is output to the camera CPU unit 1. The lens position detection unit 6 reads the rotational position of the cam cylinder constituting the lens focusing drive unit 5 described above by an encoder (configured by an optical rotary encoder, a gray code conduction pattern, a conductive brush, or the like). be able to.
Based on the detection result of the lens position detection unit 6, the camera CPU unit 1 determines whether or not the position of the shooting lens 2 is appropriate for the shooting distance to the subject detected by the distance measuring unit 4.
[0018]
FIG. 2 is a flowchart for explaining the operation of the camera according to the first embodiment.
The camera CPU unit 1 detects that the power switch (not shown) of the camera has been turned on or the release half-press switch (not shown) has been turned on, and the series of cameras from step (hereinafter abbreviated as S) 100 is performed. Start the shooting preparation operation.
In the following description, each step is performed by the camera CPU unit 1 unless otherwise noted.
[0019]
In S110, it is determined whether a release full-press switch (not shown) is ON. If the release full-press switch is ON, the photographer has instructed the start of the exposure operation, and the process proceeds to the exposure routine in S400. When the release full-press switch is not ON, since the exposure is not started, the process proceeds to S120 and the following, and the shooting preparation operation such as focusing drive is continued.
Note that the exposure routine from S400 onward is based on the conventional camera operation, and the description thereof is omitted here.
[0020]
In S120, the distance measuring unit 4 is caused to detect the shooting distance to the subject, and the distance measurement information is stored.
In S130, it is determined whether or not the distance measurement information detected in the previous S120 is the first distance measurement information. When the distance measurement performed in S120 is the first distance measurement operation, the process proceeds from S130 to S150, and in S150, the angle position information calculated by the signal from the shake detection unit 3 is reset (angle position = 0). To do).
[0021]
On the other hand, if it is determined in S130 that the distance measurement information is for the second time or later, the process proceeds from S130 to S140. In S140, the amount of change in the camera shooting direction is calculated based on the detection signal from the shake detection unit 3. The angle position information is stored.
Note that the angular position calculated here is synchronized with the timing of distance measurement in S120. That is, the distance measurement information and the angle position information are information obtained at the same time.
[0022]
In S160, the moving path and moving speed of the subject are calculated based on the distance measurement information and the angular position information obtained so far.
The procedure for calculating the movement path and movement speed of the subject will be described below.
[0023]
FIG. 3 is a diagram for explaining a change in distance measurement value for the moving body of the camera according to the first embodiment.
Assume that distance measurement is performed at time t0 and a distance measurement value R0 is obtained. As shown in FIG. 3, the subject position (coordinates) at this time is
(X0, Y0) = (R0, 0) (Formula 1-1)
And That is, an XY coordinate system with the photographing position as the origin is set, and this is performed as a point of the distance “R0” on the X axis. At this time (S150), the angle position information calculated from the signal from the shake detection unit 3 is reset (angle position = 0).
[0024]
Next, it is assumed that distance measurement is performed at time t1 after dt time to obtain a distance measurement value R1. Further, based on the signal from the shake detector 3, the angular velocity signal from time t0 to t1 is integrated to calculate the angle change amount θ1.
The subject position (coordinates) at time t1 is
(X1, Y1) = (R1, cos θ1, R1, sin θ1) (Formula 1-2)
It is.
Also, assuming that the moving speed of the subject is constant, the velocity components in the X direction and the Y direction are

It becomes. The previously defined “X-intercept” in the XY coordinate system is the subject position at time t0 (R0, 0).
By the above calculation, the moving path of the subject with respect to the photographing apparatus is obtained.
[0025]
The subject position (coordinates) at time t2 further dt hours after time t1 is

become. The distance to the subject at this time is
R2 = SQRT {(2 · R1 · cos θ1−R0) ² + (2 · R1 · sin θ1) ² } (where SQRT represents a square root) (Formula 1-5)
It becomes.
Here, when the shooting distance at the time t2 is calculated from only the shooting distances R0 and R1 at the times t0 and t1 without considering the moving path of the subject, if this calculated value is R2 ′,
R2 ′ = 2 · R1-R0 (Formula 1-6)
In the case of θ1 = 0, R2 = R2 ′, but otherwise it is a different value.
[0026]
Hereinafter, the subject position (coordinates) at time tn after n × dt hours from time t0 is
(Xn, Yn) = (n.R1.cos .theta.1- (n-1) .R0, n.R1.sin .theta.1) (Formula 1-7)
The distance to the subject at this time is
Rn = SQRT [{n · R1 · cos θ1− (n−1) · R0} ² + (n · R1 · sin θ1) ² ] (Formula 1-8)
It becomes.
[0027]
Returning to the description of FIG. In S170, the lens focusing drive unit 5 is controlled based on the moving path, moving speed, subject position expected at a certain time and the distance to the subject calculated in S160 to drive the photographing lens 2 in focus. To do.
In step S170, after the focus drive is performed, the process returns to step S110, and it is determined again whether or not a release full-press switch (not shown) is ON, and whether or not an exposure operation start instruction is issued by the photographer is determined. Hereinafter, when the process does not shift to the exposure operation, the flow from S120 described above is repeated.
[0028]
As described above, according to the first embodiment, an accurate distance change of a moving subject can be obtained by calculation using distance measurement information and angle position information to the subject, and based on the result of the calculation. Accurate focus drive can be performed. By these, it is possible to obtain a good image particularly for photographing a subject moving in an oblique direction.
[0029]
(Second Embodiment)
FIG. 4 is a diagram showing a configuration of a second embodiment of a camera to which the present invention is applied.
The single-lens reflex camera shown in FIG. 4 has a focus detection unit 8 that detects the focal position of a subject image obtained through the photographing lens 2 instead of the distance measuring unit 4 of the camera described in FIG.
Since the camera CPU unit 1, the photographing lens 2, the blur detection unit 3, the lens focusing drive unit 5, and the lens position detection unit 6 are the same as those in the embodiment of FIG. 1, only the portions different from those in FIG.
[0030]
The mirror unit 7 is a mirror that guides subject light transmitted through the photographing lens 2 to a finder screen and a focus detection unit 8 (described later), and includes a main mirror that is a semi-transmissive mirror and a sub mirror that is a reflection mirror. ing.
[0031]
The focus detection unit 8 is a part that detects the focus position of the subject image obtained through the photographing lens 2, and here, a focus detection device of a divided pupil system is used.
[0032]
The lens position detection unit 6 detects the position of the taking lens 2 driven by the lens focusing drive unit 5 in the optical axis direction. Based on the detection result, the camera CPU unit 1 monitors whether or not the position of the photographing lens 2 is appropriate for the photographing distance to the subject detected by the distance measuring unit 4.
[0033]
Here, the camera CPU unit 1 of the present embodiment calculates the distance to the subject from the focus position information obtained from the focus detection unit 8 and the lens position information obtained from the lens position detection unit 6 by calculation. This calculation can be easily performed geometrically if the focal length and focal position of the lens are known.
[0034]
If the photographing lens 2 is a zoom lens and the focal length of the lens at the time of photographing may change, a zoom position detecting unit (not shown) is further added to the lens position detecting unit 6. Information on the actual focal length of the photographing lens 2 at the focal position detection time by the focal point detection unit 8 such as the times t0 and t1 described in FIG. In this way, the camera CPU unit 1 can calculate the distance to the subject at each time.
[0035]
According to the second embodiment, since the distance to the subject can be obtained by the focus detection output and the position information of the photographing lens, the present invention can be easily applied to an AF single-lens reflex camera having a focus detection unit.
[0036]
(Third embodiment)
FIG. 5 is a flowchart for explaining the operation of the camera according to the third embodiment.
Since the third embodiment can be expressed in the same manner as FIG. 1 showing the configuration of the first embodiment, it will be described with reference to FIG.
The camera CPU unit 1 detects that the power switch (not shown) of the camera has been turned on or the release half-press switch (not shown) has been turned on, and the series of cameras from step (hereinafter abbreviated as S) 100 is performed. Start the shooting preparation operation.
In the following description, each step is performed by the camera CPU unit 1 unless otherwise noted.
[0037]
In S210, it is determined whether or not a release full-press switch (not shown) is ON. If the release full-press switch is ON, the photographer has instructed the start of the exposure operation, and the process proceeds to the exposure routine in S400. When the release full-press switch is not ON, since the exposure is not started, the process proceeds to S220 and the subsequent steps, and the shooting preparation operation such as focusing drive is continued.
Note that the exposure routine from S400 onward is based on the conventional camera operation, and the description thereof is omitted here.
[0038]
In S220, the distance measurement unit 4 is caused to detect the shooting distance to the subject, and the distance measurement information is stored. For example, the object distance measured first at time t0 is R0.
When passing through S230 for the first time, that is, when the distance measurement information detected in the previous S220 is the first distance measurement information, since it is impossible to measure and calculate the distance change to the subject, the calculation is performed in this step. Pass without doing.
[0039]
Next, in S240, the blur detection unit 3 is caused to detect the angular velocity, and information on the angular velocity applied to the camera is stored. For example, the angular velocity detected first at time t0 ′ (may be simultaneous with t0 or different) is ω0.
Similarly to S230, the determination and correction steps from S250 to S280 cannot be determined for the change in angular velocity when passing for the first time, and therefore, these steps pass without performing computation.
[0040]
In S290, based on the distance information to the subject obtained in the previous S220, focusing movement control of the lens focusing driving unit 5 is performed to adjust the focal position of the photographing lens 2.
[0041]
Next, the second and subsequent routines will be described.
Steps S210 and S220 are executed, and in step S230, the speed of the distance change to the approaching subject is calculated based on the distance measurement information obtained so far. In the second and subsequent routines, the calculation performed in S230 is according to the following equation.
In the previous routine, the subject distance measured at time t0 is R0. In this routine, the subject distance measured at time t1 is R1. If the time from the previous distance measurement to the current distance measurement is dt, the distance change speed dR / dt to the subject is expressed by the following equation.
dR / dt = (R1-R0) / dt (Formula 2-1)
[0042]
A future distance change can be predicted based on the speed of the distance change obtained as described above. For example, the subject distance (estimated value) R2 ^ at time t2 after dt time further than time t1 is calculated as the following value.
R2 ^ = R1 + dR.dt = 2.R1-R0 (Formula 2-2)
[0043]
The focus drive control performed in S290 later may be performed by causing the lens focus drive unit 5 to adjust the focus position of the taking lens 2 based on the above result. The situation from S250 to S280 described below is further described. When the determination and the correction are performed, the accuracy of the focus drive by the lens focus drive unit 5 is improved.
[0044]
The determination and correction from S250 to S280 will be described below.
In S240, the angular velocity information detected at time t0 ′ in the previous routine is set to ω0. In addition, the angular velocity information detected in the current routine at time t1 ′ (may be the same as or different from the previous t1) is ω1.
[0045]
In S250, the magnitudes of ω0 and ω1 are compared. If ω0 <ω1, the process proceeds to S260. Otherwise, jump to S260 and proceed to S270. When ω0 <ω1, the angular velocity applied to the camera tends to increase when trying to keep the moving subject in the shooting area.
[0046]
FIG. 6 is a diagram for explaining a change in distance to a subject moving at a constant speed by the camera according to the second embodiment and a change in angular velocity applied to the camera when trying to keep the subject in the shooting region. .
Assume that angular velocity detection is performed at time t0 ′ (for simplicity here, t0 ′ = t0), and an angular velocity detection value ω0 is obtained.
If the moving speed of the moving subject at this time is V, ω0 can be expressed by the following equation.
ω0 = (V · sin θ0) / R0 (Formula 2-3)
[0047]
Next, it is assumed that angular velocity detection is performed at time t1 ′ (for simplicity, t1 ′ = t1) to obtain an angular velocity detection value ω1.
The moving subject is moving at the same moving speed V, and ω1 can be expressed by the following equation.
ω1 = (V · sin θ1) / R1 (Formula 2-4)
[0048]
Here, consider the magnitude of ω0 and ω1. Since the subject is approaching, θ is 0 ≦ θ ≦ π / 2 (rad).
FIG. 6 shows that sin θ0 <sin θ1. It can also be seen that R0> R1. Therefore, it can be seen from the relationship between the numerator and the denominator on the right side of (Formula 2-3) and (Formula 2-4) that ω0 <ω1 in the situation of FIG.
[0049]
From the above magnitude relationship, when a subject moving at a constant speed approaches obliquely, ω0 <ω1 holds. Further, from the relations of (Equation 2-3) and (Equation 2-4) described above, the angular velocity tends to increase until the subject is closest, and conversely, the subject passes the closest position. When moving away, the angular velocity is decreasing.
[0050]
Next, the plus correction performed in S260 will be described.
The distance change speed calculated in S230 causes an error when a subject moving at a constant speed as shown in FIG. 6 approaches obliquely.
Assume that distance measurement is performed at time t0 and a distance measurement value R0 is obtained. As shown in FIG. 6, the subject position (coordinates) at this time is as follows.
(X0, Y0) = (R0, 0) (Formula 2-5)
[0051]
That is, an XY coordinate system with the shooting position as the origin is set, and this is set as a point of distance on the X axis R0.
The moving speed of the subject is V, the X-axis direction component is Vx, and the Y-axis direction component is Vy. An angle between the moving direction of the subject and the X axis defined above is defined as θ0.
Next, it is assumed that distance measurement is performed at time t1 after dt time to obtain a distance measurement value R1. During this time, the subject moves from the position (R0, 0) by (−Vx · dt, Vy · dt). R1 takes the following values.
R1 = SQRT {(R0−Vx · dt) ² + (Vy · dt) ² } (where SQRT is a square root) (Formula 2-6)
[0052]
Therefore, the estimated value R2 ^ of the distance to the subject at time t2 after dt time is expressed by the following expression 2-7.
R2 ^ = R1 + dR = 2.R1-R0 (Formula 2-7) = (Formula 2-2)
For example, when the subject position (X0, Y0) = (20, 0), Vx · dt = 4, and Vy · dt = 3 at time t0,

[0053]
However, the true position of the subject at time t2 is
(R0-2 · Vx · dt, 2 · Vy · dt) The distance R2 to the true subject is the following value.

[0054]
As described above, when a subject moving at a constant speed approaches obliquely as compared to the estimated value of the distance to the subject by the calculation of (Equation 2-7) = (Equation 2-2), it is more than expected. The change speed of the distance is small, and the distance after a predetermined time becomes longer than expected. In other words, the distance change speed must be re-estimated.
[0055]
Returning to the description of FIG. In S250, the magnitudes of ω0 and ω1 are compared. If ω0 <ω1, the process proceeds to S260. Otherwise, the process proceeds to S270.
In S260, reduction correction (correction is performed so that the absolute value of the distance change speed becomes smaller) is performed on the distance change speed calculated in S230 according to the situation where the moving subject approaches obliquely.
The correction coefficient varies depending on the moving speed of the subject and the condition of the moving path approaching diagonally. However, according to experiments that take into account the frequency of the situation where the camera is actually used, several correction coefficients are set according to changes in angular speed. What is necessary is just to memorize | store in the memory | storage part in the camera CPU unit 1. FIG.
[0056]
Next, in S270, it is determined whether or not ω0> ω1. If ω0> ω1, the process proceeds to S280. If ω0> ω1, the process jumps to S280 and proceeds to S290.
In S280, enlargement correction is performed on the distance change speed calculated in S230 (correction so that the absolute value of the distance change speed is increased) according to the situation where the moving subject moves away obliquely.
The correction coefficient varies depending on the moving speed of the subject and the moving path that moves diagonally away. However, according to an experiment that considers the frequency of the situation in which the camera is actually used, as in S260, there are several correction coefficients. The correction coefficient may be stored in the storage part in the camera CPU unit 1.
[0057]
In S290, the focusing movement of the lens focusing drive unit 5 based on the distance change speed calculation result to the subject obtained in the previous S230 or the correction performed in S260 or S280 on the calculation result. Control is performed to adjust the focal position of the taking lens 2.
After S290, the process returns to S210, and it is determined whether or not a release full-press switch (not shown) is ON, and the presence or absence of an exposure operation start instruction by the photographer is determined. Hereinafter, if the process does not shift to the exposure operation, the flow from S220 onward is repeated.
[0058]
When shooting a subject approaching the camera at a constant speed, the angular velocity applied to the camera is small at first, but gradually increases and reaches the maximum at the closest point. As the subject moves away from the camera, the angular velocity decreases again.
On the other hand, considering the relative distance change between the subject and the camera, the distance is initially reduced at approximately the same speed as the subject's moving speed, but when the subject approaches, it moves in an oblique direction toward the camera. Thus, the mutual distance change is smaller than the moving speed of the subject. At the closest point, the subject moves in the lateral direction with respect to the camera, so that the distance change is only slight. When the subject moves away from the camera again, the opposite is true.
[0059]
With the above operation, the distance change speed of the moving subject can be obtained by calculation using the distance measurement information on the moving subject and the angular velocity information added to the camera when trying to keep the subject in the shooting area. . That is, in the present invention, the change in the distance to the subject and the angular velocity applied to the camera is detected, and the relative distance change between the camera and the moving subject is corrected and calculated from those detection signals. It is now possible to predict changes in shooting distance with simple calculations.
Since accurate focusing drive based on the result can be performed, a good image can be obtained particularly for photographing a subject moving in an oblique direction.
[0060]
In the example described with reference to FIG. 5, the determination in S250 and S270 is ω0 <ω1 or ω0> ω1, but this is set to ω0−ω1 <C1 or ω0−ω1> C2 so that a predetermined insensitive area is obtained. (C1 and C2 are predetermined constants).
This is because there is an effect of preventing the focus drive control from becoming unstable due to frequent correction.
[0061]
In addition, the times t0 and t1 for detecting R0 and R1 and the times t1 ′ and t2 ′ for detecting ω0 and ω1 do not need to be the same time, but this is an increase in angular velocity or This is because it is not always necessary to be the same as the timing of distance measurement because it is only determined whether or not it is decreasing.
In the above example, the speed of changing the distance to the subject is determined by obtaining a linear coefficient from the current and past two pieces of distance measurement information. However, the present invention is not limited to this method. An arithmetic method for obtaining a quadratic or higher regression curve using the current and past three or more distance measurement information may be used.
[0062]
Moreover, although the change of angular velocity was calculated | required from the present and past angular velocity information, you may make it obtain angular acceleration information also using an angular acceleration sensor. Of course, two or more acceleration sensors may be used in combination, and the angular acceleration may be calculated from the difference between the acceleration sensors.
[0063]
(Fourth embodiment)
In the fourth embodiment, the method of the third embodiment is applied to the configuration represented in the same manner as the embodiment of FIG. 4, and the configuration will be described with reference to FIG.
The single-lens reflex camera according to the fourth embodiment includes a mirror unit 7 and a photographing lens 2 in addition to a camera CPU unit 1, a photographing lens 2, a blur detection unit 3, a lens focusing driving unit 5, and a lens position detection unit 6. A focus detection unit 8 that detects the focus position of the obtained subject image is provided.
[0064]
The mirror unit 7 is a mirror that guides the subject light transmitted through the photographing lens 2 to the finder screen and the focus detection unit 8, and includes a main mirror that is a semi-transparent mirror and a sub mirror that is a reflection mirror.
[0065]
The focus detection unit 8 is a part that detects the focus position of the subject image obtained through the photographing lens 2, and here, a focus detection device of a divided pupil system is used.
[0066]
The lens position detection unit 6 detects the position of the taking lens 2 driven by the lens focusing drive unit 5 in the optical axis direction. Based on the detection result, the camera CPU unit 1 monitors whether or not the position of the photographing lens 2 is appropriate for the photographing distance to the subject detected by the distance measuring unit 4.
[0067]
Here, the camera CPU unit 1 of the present embodiment calculates the distance to the subject from the focus position information obtained from the focus detection unit 8 and the lens position information obtained from the lens position detection unit 6 by calculation. This calculation can be easily performed geometrically if the focal length and focal position of the lens are known.
[0068]
If the photographing lens 2 is a zoom lens and the focal length of the lens at the time of photographing may change, a zoom position detecting unit (not shown) is further added to the lens position detecting unit 6. What is necessary is just to be able to obtain information on the actual focal length of the photographic lens 2 at the focus position detection time by the focus detection unit 8 such as the times t0 and t1 described in the previous FIG. In this way, the camera CPU unit 1 can calculate the distance to the subject at each time.
[0069]
(Fifth embodiment)
The camera of the fifth embodiment is obtained by omitting a zoom position detection unit (not shown) that is a part of the function of the lens position detection unit 6 in the camera described in the fourth embodiment.
If a part of the function of the lens position detection unit 6 is omitted as in the fifth embodiment, the camera CPU unit 1 cannot convert the distance from the focus position information to the subject, but the current focus position and the normal alignment. Since the difference from the focal position is known, the drive control of the lens focusing drive unit 5 is possible.
[0070]
FIG. 7 is a flowchart for explaining operations performed in the fifth embodiment of the camera to which the present invention is applied. Description of the same parts as those in FIG. 5 is omitted.
The camera CPU unit 1 starts a series of shooting preparation operations of the camera from S300. In S310, it is determined whether or not a release full press switch (not shown) is ON. If the release full press switch is ON, the process proceeds to the exposure routine of S400, and if not, the process proceeds to S320 and thereafter.
[0071]
In S320, the focus detection unit 8 is caused to detect the focus position, and the focus position information is stored. For example, assume that the first detected focal position at time t0 is Z0. Hereinafter, when first passing through S330 and S350 to S380, as in the case described in the third embodiment , the processing passes without performing each process.
[0072]
In S340, the blur detection unit 3 is caused to detect the angular velocity, and information on the angular velocity applied to the camera is stored. For example, the angular velocity detected first at time t0 ′ (may be simultaneous with t0 or different) is ω0.
In S390, based on the focal position information obtained in the previous S320, the focusing movement control of the lens focusing driving unit 5 is performed, and the focal position of the photographing lens 2 is adjusted.
[0073]
Next, the second and subsequent routines will be described.
In the second and subsequent S330s, the focal position change speed of the subject image is calculated based on the information obtained so far. The focus position detected at time t0 in the previous routine is set to Z0. In this routine, the focal position detected at time t1 is set to Z1. If the time interval between the previous time and this time is dt, the focal position change speed dZ / dt is as follows.
dZ / dt = (Z1-Z0) / dt (Formula 2-12)
[0074]
As described above, the focal position change speed of the subject image can be calculated, and the future focal position can be predicted. For example, the focal position (estimated value) Z2 ^ at time t2 after dt time further than time t1 is calculated as the following value.
Z2 ^ = Z1 + dZ.dt = 2.Z1-Z0 (Formula 2-13)
When the focus position of the taking lens 2 has already been driven by the lens focusing drive unit 5 based on the previously detected focus position Z0, it is necessary to consider the amount already driven (−Z0). Therefore, the change speed dZc / dt of the focal position is expressed by the following equation.

[0075]
In S340, the angular velocity is detected and stored at time t1 ′ (may be simultaneous with t1 or may be different).
In the previous routine, the angular velocity information detected at time t0 ′ is ω0, and the angular velocity information detected in the current routine is ω1.
[0076]
The determination and correction from S350 to S380 are the same as those in the third embodiment . When a subject moving at a constant speed approaches obliquely, ω0 <ω1 holds until the subject comes closest, and the angular velocity tends to increase. On the contrary, the subject passes away from the closest location. Sometimes, ω0> ω1, and the angular velocity tends to decrease. Therefore, first, in S350, the determination of ω0 <ω1 is performed. If ω0 <ω1, the process proceeds to S360. Otherwise, the process proceeds to S370.
[0077]
In S360, the focal position change speed is corrected in the same manner as described in S260 of the third embodiment . The situation up to S360 is a case where the moving subject is approaching obliquely, and the subject is not closer than expected as described in the third embodiment . In other words, it is necessary to correct the distance changing speed to the subject to be small. This also requires correction of the position change speed for the focus position change speed (correction so that the absolute value of the position change speed becomes smaller). Therefore, in S360, reduction correction is performed on the focal position change speed calculated in S330. The correction coefficient varies depending on the moving speed of the subject and the condition of the moving path approaching diagonally. However, according to the experiment considering the frequency of the situation where the camera is actually used, several correction coefficients May be stored in a storage portion in the camera CPU unit 1.
[0078]
Next, in S370, it is determined whether or not ω0> ω1. If ω0> ω1, the process proceeds to S380. Otherwise, the process proceeds to S390.
In S380, enlargement correction (correction so that the absolute value of the position change speed is increased) is performed on the focal position change speed calculated in S330 according to the situation in which the moving subject moves away obliquely.
The correction coefficient differs depending on the moving speed of the subject and the situation of the moving path that moves obliquely. However, according to the experiment considering the frequency of the situation in which the camera is actually used, as in S360, there are several correction coefficients. These correction coefficients may be stored in a storage portion in the camera CPU unit 1.
[0079]
In S390, based on the calculation result of the focal position change speed to the subject obtained in the previous S330 or the correction performed on the calculation result in S360 or S380, the focusing of the lens focusing drive unit 5 is performed. Dynamic control is performed to adjust the focal position of the taking lens 2.
[0080]
After S390, the process returns to S310, and it is determined whether or not a release full-press switch (not shown) is ON to determine whether or not there is an exposure operation start instruction from the photographer. Hereinafter, if the process does not shift to the exposure operation, the flow from S320 described above is repeated.
[0081]
By the above operation, the focal position change speed of the subject image can be obtained by calculation using the focal position information of the subject and the angular velocity information added to the camera when trying to keep capturing the subject in the shooting region. Accurate focusing drive based on the result can be performed. As a result, a good image can be obtained particularly for photographing a subject moving in an oblique direction.
[0082]
In the example described with reference to FIG. 7, the determination in S350 and S370 is set to ω0 <ω1 or ω0> ω1, but this is set to ω0−ω1 <C3 or ω0−ω1> C4 so that a predetermined insensitive area is obtained. (C3 and C4 are predetermined constants).
This is because there is an effect of preventing the focus drive control from becoming unstable due to frequent correction.
[0083]
In addition, the times t0 and t1 for detecting R0 and R1 and the times t1 ′ and t2 ′ for detecting ω0 and ω1 do not need to be the same time, but this is an increase in angular velocity or This is because it is not always necessary to be the same as the timing of distance measurement because it is only determined whether or not it is decreasing.
Further, in the above example, the focus position change speed of the subject image is obtained from the current and past two focus detection information, but is not limited to this method. An arithmetic method for obtaining a quadratic or higher regression curve using three or more pieces of current and past information may be used.
Furthermore, although the change of the angular velocity is obtained from the current and past angular velocity information, the angular acceleration information may also be obtained using an angular acceleration sensor. Of course, two or more acceleration sensors may be used in combination, and the angular acceleration may be calculated from the difference between the acceleration sensors.
[0085]
In the embodiment described above, the change in the distance to the subject (predicted value) calculated by the camera CPU unit 1 is used for operation control of the lens focusing drive unit 5, but can be used for other purposes. . For example, a display unit for displaying the predicted value is provided, and a focus is set to a predetermined shooting distance, and a shutter is opened by predicting a time point when the subject reaches the position. It may be. In addition, when performing strobe shooting, it is possible to control to emit light by predicting that the subject has moved to a shooting possible distance (strobe light arrival distance) according to the guide number. Furthermore, when shooting a similar scene at the same scale, the position of the moving subject may be predicted and used when shooting at the same point.
[0086]
【The invention's effect】
As described above in detail, the present invention detects the distance to the moving body and the moving direction (for example, change in the orientation of the apparatus), and calculates, for example, the subject moving path and the moving speed from the detection signals. Therefore, it is possible to accurately predict a change in the distance to the moving body by a simple calculation. In addition, since the focusing lens can be appropriately driven based on the predicted distance measurement value, a moving subject can always be captured with a clear image.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a first embodiment of a camera to which the present invention is applied.
FIG. 2 is a flowchart for explaining the operation of the camera according to the first embodiment.
FIG. 3 is a diagram for explaining a change in distance measurement value with respect to the moving body of the camera according to the first embodiment.
FIG. 4 is a diagram showing a configuration of a second embodiment of a camera to which the present invention is applied.
FIG. 5 is a flowchart illustrating the operation of a camera according to a third embodiment.
FIG. 6 is a diagram for explaining a change in distance to a subject moving at a constant speed by the camera according to the third embodiment and a change in angular velocity applied to the camera when trying to keep the subject in the shooting region. .
FIG. 7 is a flowchart illustrating the operation of a camera according to a fifth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Camera CPU unit 2 Shooting lens 3 Blur detection part 4 Distance measurement part 5 Lens focusing drive part 6 Lens position detection part 7 Mirror part 8 Focus detection part

Claims (7)

A distance measuring unit for detecting the distance to the moving object;
An angle detector that detects an angle or an angular velocity of the device that changes according to a moving direction of the moving body;
A prediction calculation unit that obtains a movement locus of the moving body based on the detection output of the distance measuring unit and the detection output of the angle detection unit, and predicts a change in the distance to the moving body based on the movement locus. Predictive ranging device. The predictive ranging apparatus according to claim 1 ,
The distance measuring unit is
A focus detection unit for detecting the imaging state of the moving body by the optical system of the apparatus;
A predictive distance measuring device comprising: an adjustment amount detecting unit that detects an adjustment amount in an optical axis direction of an optical system of the device. The predictive distance measuring device according to claim 1 or 2,
The prediction calculation unit includes a moving body speed calculation unit that calculates a moving direction and a moving speed of the moving body based on the detection output of the distance measurement unit and the detection output of the angle detection unit. Distance measuring device. The predictive ranging apparatus according to any one of claims 1 to 3 ,
The angle detector
An angular velocity sensor that outputs an angular velocity signal;
A predictive ranging apparatus comprising: an angle calculation unit that integrates an output of the angular velocity sensor to calculate an angle change amount. In the prediction ranging apparatus of any one of Claim 1 to 4 ,
The said angle detection part calculates the said angle variation | change_quantity synchronizing with the ranging timing of the said ranging part, The prediction ranging apparatus characterized by the above-mentioned. The predictive distance measuring device according to any one of claims 1 to 5 ,
The distance measuring unit detects distances R0 and R1 to the moving body at predetermined times t0 and t1,
The said angle detection part detects the variation | change_quantity (theta) 1 of the direction of a moving body from the said predetermined time t0 to t1, The prediction ranging apparatus characterized by the above-mentioned. The predictive ranging apparatus according to any one of claims 1 to 6 ,
A focusing drive for adjusting the imaging state of the optical system of the apparatus;
An imaging device including an in-focus control unit that controls an operation of the in-focus driving unit based on an output of the predictive distance measuring device.

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