JP4324318B2 - Autofocus device - Google Patents

Description

【００２８】
図１１において、フラッシュズーム変更サブルーチンが開始されると、始めにステップＳ４０１において、ＡＦモードがスポットＡＦモードであるか否かが判定される。スポットＡＦであるならば（Ｓ４０１：ＹＥＳ）、焦点検出に利用される焦点検出エリアは撮影画面８８における中央のエリアＣのみなので、発光部ユニット８２のズーム位置として最もテレ側のズーム位置である８５ｍｍが選択され（Ｓ４０３）、フラッシュズームデータとして値５とすることが決定される（Ｓ４１２）。また、ステップＳ４０２において、ユーザー選択ＡＦモードにより選択された焦点検出エリアがエリアＣ又はＣＣである場合にも、発光部ユニット８２のズーム位置として最もテレ側のズーム位置である８５ｍｍが選択される（Ｓ４１２）。エリアＣやエリアＣＣでは焦点検出エリアが中央付近に限定されているため、ＡＦ補助光を中央に絞ることができる。したがって、この場合、発光部ユニット８２ズーム位置が、最もテレ側の位置とされ、撮影レンズの焦点距離８５ｍｍの画角をカバーするのに十分な範囲にまで照射角が絞られる。すなわち、焦点検出に利用されない焦点検出エリアにまでフラッシュ光が拡散することが防止される。
【００２９】
スポットＡＦモードでもなく、さらにユーザー選択された場合のエリアがＣでもＣＣでもない場合には（Ｓ４０２：ＮＯ）、ステップＳ４０４においてＡＦモードがワイドＡＦモードであるか否かが判定される。ワイドＡＦモードである場合（Ｓ４０４：ＹＥＳ）、ステップＳ４０６において、発光部ユニット８２のズーム位置として最もワイド側のズーム位置である２４ｍｍが選択される。また、ステップＳ４０５において、ユーザー選択ＡＦモードにより選択された焦点検出エリアがエリアＬＬ又はＲＲである場合も（Ｓ４０５：ＹＥＳ）、発光部ユニット８２のズーム位置として最もワイド側のズーム位置である２４ｍｍが選択され（Ｓ４０６）、発光部ユニット８２のズーム位置が最もワイド側の位置とされ、撮影レンズの焦点距離２４ｍｍの画角をカバーする広い照射角での照射が行われる。すなわち、撮影画面８８の端に近い焦点検出エリアにも、補助光が有効に届いて被写体を照明できるように、できるだけ広い角度で照射するように構成されている。
【００３０】
ワイドＡＦモードでもなく、さらにユーザー選択された場合のエリアがＬＬでもＲＲでもない場合には（Ｓ４０５：ＮＯ）、ステップＳ４０７においてＡＦモードが中央３点ＡＦモードであるか否かが判定される。中央３点ＡＦモードである場合（Ｓ４０７：ＹＥＳ）、ステップＳ４０９において、フラッシュズームデータに設定すべき値（変数“Z”）は、撮影レンズ５０の焦点距離（撮影レンズがズームレンズである場合には現在の焦点距離）に対応するフラッシュズームデータの値に３が加えた値とされる。ステップＳ４０９の加算の結果が５を超える場合には、すなわち発光部ユニット８２の最もテレ側に対応する値を超える場合には（Ｓ４１０：ＹＥＳ）、“Z”の値はフラッシュズームデータとしての最大値である５とされる。すなわち、ＡＦ対象エリアが撮影画面８８の中心部近辺に位置するため、発光部ユニット８２のズーム位置を撮影レンズの焦点距離よりもテレ側に定め、補助光の照射角を絞り込むことが可能である。したがって、ステップＳ４０９において、撮影レンズの焦点距離に対応するフラッシュズームデータに３を加えた値が、フラッシュズームデータとして決定される。なお、この３という値は、これに限定されるものでなく、フラッシュズームデータを撮影レンズの焦点距離よりもテレ側の値で焦点検出エリアをカバーするものであれば他の値であっても良い。ステップＳ４１２では、以上のフラッシュズームデータとして決定された値が、変数に設定される。次に、設定されたフラッシュズームデータが、ＣＰＵ２０からフラッシュ装置８０側に送信される（Ｓ４１３）。フラッシュ装置８０では、受信したフラッシュズームデータにしたがって発光部ユニット８２がズーム駆動される。そして、ステップＳ４１４において所定時間ウェイトした後、サブルーチンは終了する。
【００３１】
図３に戻って、ステップＳ１０７において、フラッシュズーム変更処理が終了すると、処理はステップＳ１０８に進む。ステップＳ１０８では、フラッシュ補助光を照射しての積分処理が行われる。ステップＳ１０８にいて呼び出される「フラッシュ補助光＆積分」サブルーチンの詳細を図１２に示す。
【００３２】
図１２の「フラッシュ補助光＆積分」処理では、フラッシュ補助光を発光しながら積分処理が実行されるが、以下で説明するように、発光部ユニット８２のズーム位置に応じて発光量が制御され、発光量の効率化が行われる。すなわち、発光部ユニット８２の位置がテレ側であるほど、照射角は絞られているため、発光量を抑えることが可能となる。したがって、図１２の処理では、フラッシュズームデータの値に応じて、その値がテレ側であるほど発光量が抑えられる。また、図１２の処理において、フラッシュ光は間欠発光される。この間欠発光は、ステップＳ５０３、ステップＳ５０４において算出される発光時間、発光間隔にしたがって行われる。このとき、１回の発光でＣＣＤセンサユニット６の積分値が許容範囲を超えてしまい、また、被写体に対して発光回数が増えすぎてしまうことを避けるために、発光量を発光回数にしたがって段階的に増加させる制御も行われる。なお、発光回数にしたがって増加する発光量に対し十分であるように、発光時間間隔、すなわち充電時間も増加される。
【００３３】
図１２において、始めに発光回数がクリアされる（Ｓ５０１）。次に、ＣＣＤセンサユニット６における積分処理が開始される（Ｓ５０２）。ステップＳ５０３において、発光時間が次の定義に従って決定される。
発光時間＝基準発光時間＋補正時間×（発光回数÷補正回数）
また、ステップＳ５０４において、発光間隔が次の定義に従って決定される。
発光間隔＝基準発光間隔＋補正間隔×（発光回数÷補正回数）
ただし、これらの式において、（発光回数÷補正回数）は、小数点以下を切捨てとする。
【００３４】
１回目の発光時間を規定する基準発光時間は、フラッシュズームデータに応じて、表２に示す対応関係となるように決定される。表２に示すように、発光部ユニット８２のズーム位置がテレ側であるほど、基準発光時間が短くなる。したがって、発光部ユニット８２のズーム位置がテレ側であるほど、発光量が減じられる。なお、表２に示すテーブルは、ＣＰＵ２０内のＲＯＭに格納され、ＣＰＵ２０はテーブルをＣＰＵ２０内のＲＡＭに読み出して使用する。
【００３５】
【表２】

【００３６】
発光時間、発光間隔を決定する他のパラメータである、補正時間、補正回数、基準発光間隔及び補正間隔も、基準発光時間と同様に、ＣＰＵ２０が内部のＲＯＭに保持している。ステップＳ５０５では、発光時間にしたがって、発光部ユニット８２を発光させる処理が行われる。ステップＳ５０６では、発光回数が１つカウントアップされる。ステップＳ５０７では、あらかじめ定められる最大発光回数に達しているか否かが判定される。最大発光回数に達していると（Ｓ５０７：ＹＥＳ）、サブルーチンは終了する。最大発光回数まで達していなければ（Ｓ５０７：ＮＯ）、ＣＣＤセンサユニット６において、ＡＦ対象の焦点検出エリアに所定量の電荷が蓄積されることにより積分が終了しているか否かが判定される。積分が終了していると（Ｓ５０８：ＹＥＳ）、サブルーチンは終了する。所定量の電荷蓄積量に達せず積分終了していない場合には（Ｓ５０８：ＮＯ）、ステップＳ５０４で決定された発光間隔にしたがって発光が停止される（Ｓ５０９）。次に、ステップＳ５０３からの発光処理が繰り返される。
【００３７】
それぞれのパラメータが以下であった場合の、発光回数にしたがう発光時間を表３に示す。
基準発光時間＝１０μｓ
補正時間＝２μｓ
基準発光間隔＝１０ｍｓ
補正間隔＝２ｍｓ
補正回数＝２回
最大発光回数＝１０回
表３に示すように、発光時間は発光回数に従って増加される。
【００３８】
【表３】

【００３９】
図３のフローチャートに戻って、ステップＳ１０８において積分が終了すると、ステップＳ１０９において、積分結果に基づいてデフォーカス量を演算する測距演算が実行される。有効なデフォーカス量が得られ測距ＯＫである場合には（Ｓ１１０：ＮＯ）、フラッシュ補助光測距ＯＫフラグが“１”にセットされる。有効なデフォーカス量が得られず測距ＮＧである場合には（Ｓ１１０：ＹＥＳ）、フラッシュ補助光測距ＮＧフラグが“１”にセットされ、処理は図４のステップＳ１１３に進む。
【００４０】
ステップＳ１１３では、ＡＦモードが、中心部のスポット（焦点検出エリアＣ）のみを用いるスポットＡＦモードでなく、ワイドＡＦモードや中央３点ＡＦモードなどのように広い範囲の焦点検出エリアをＡＦ対象エリアとするエリアＡＦモードであるか否かが判定される。エリアＡＦモードである場合には（Ｓ１１３：ＹＥＳ）、処理はステップＳ１１６に進む。また、フラッシュ補助光による積分及び測距演算（Ｓ１０８，Ｓ１０９）においてコントラスト値が規定値以上ある場合には（Ｓ１１４：ＹＥＳ）、処理はステップＳ１１６に進む。すなわち、エリアＡＦモードでは、投光ＬＥＤ８５は用いられない。ステップＳ１１６では、フラッシュ補助光フラグが“１”にセットされ、フラッシュ補助光による測距演算結果が有効にされる。次に、ステップＳ１１７において、フラッシュ補助光による測距結果がＯＫである場合には（Ｓ１１７：ＮＯ）、処理はステップＳ１５２に進む。すなわち、エリアＡＦモードであるか又はフラッシュ補助光で被写体を検出した場合のコントラストが規定値以上あり、かつ、測距演算もＯＫである場合には、ステップＳ１５２以降の処理においてフラッシュ補助光の測距結果にしたがってのレンズ駆動が開始される。
【００４１】
エリアＡＦモードでなく、かつフラッシュ補助光で検出されたコントラストが規定値以上に達していない場合には、ステップＳ１１５において投光ＬＥＤの使用が許可されているかどうかが判定される。図１に示すように、フラッシュ装置８０内に、投光ＬＥＤ８５が搭載されているような場合には、投光ＬＥＤを使用することができるので、投光ＬＥＤ許可となる。なお、投光ＬＥＤが許可されていない場合には（Ｓ１１５：ＮＯ）、処理はステップＳ１１６に進む。
【００４２】
投光ＬＥＤ許可である場合には（Ｓ１１５：ＹＥＳ）、ステップＳ１１９において被写体に投光ＬＥＤ８５から投光パターンを投射しての積分が行われ、ステップＳ１２０において測距演算が実行される。次に、ステップＳ１２１において測演算結果が判定される。
【００４３】
測距ＯＫである場合には処理はステップＳ１２６に進む。ステップＳ１２６において、フラッシュ補助光測距がＮＧであると判定されと（Ｓ１２６：ＹＥＳ）、投光ＬＥＤフラグが“１”にセットされて、処理はステップＳ１５２以降の処理に進む。投光ＬＥＤフラグがセットされているので、投光ＬＥＤによる測距結果が有効とされるとともに、ステップＳ１５２以降の処理で、一旦合焦された後の合焦状態の確認のための再発光処理におけるＡＦ補助光として、投光ＬＥＤが使用されることになる。ステップＳ１２６においてフラッシュ補助光測距がＯＫであると判定される場合には（Ｓ１２６：ＮＯ）、処理はスタップＳ１２７に進む。
【００４４】
処理がステップＳ１２７に進むのは、フラッシュ補助光及び投光ＬＥＤの測距が両方ＯＫである場合である。この場合には、相関計算や補間計算から成る位相差方式の測距演算過程を経て得られる測距演算結果の信頼性が比較される。例えば、相関計算における相関度が高いほど、測距結果の信頼性は高いとされる。また、例えば、相関計算において算出される演算値の傾きが急峻であるほどコントラストが高いので、この傾きに基づいて測距結果の信頼性の優劣を判別する。フラッシュ補助光による測距演算の信頼性のほうが高い場合には（Ｓ１２７：ＹＥＳ）、ステップＳ１２８においてフラッシュ補助光フラグが“１”にセットされ、フラッシュ補助光による測距演算結果が有効にされる。投光ＬＥＤによる測距演算の信頼性のほうが高い場合には（Ｓ１２７：ＮＯ）、ステップＳ１２９において投光ＬＥＤフラグが“１”にセットされ、投光ＬＥＤによる測距演算結果が有効にされる。その後、処理はステップＳ１５２以降の処理に移り、有効であるとされる方の補助光による測距結果に基づいてレンズ駆動が開始される。また、一旦合焦された後の合焦状態の確認のための再発光処理におけるＡＦ補助光として、ステップＳ１２８又はＳ１２９で有効とされている方の補助光が使用されることになる。
【００４５】
一方、ステップＳ１２１において投光ＬＥＤによる測距演算がＮＧである場合には（Ｓ１２１：ＹＥＳ）、ステップＳ１２２においてフラッシュ補助光による測距結果が判定される。ステップＳ１２２において、フラッシュ補助光による測距結果がＯＫであると判定される場合には（Ｓ１２２：ＮＯ）、処理はステップＳ１２８に進みフラッシュ補助光フラグが“１”にセットされる。ステップＳ１２２においてフラッシュ補助光による測距結果がＮＧであると判定された場合には（Ｓ１２２：ＹＥＳ）、処理はステップＳ１２３に進む。
【００４６】
処理がステップＳ１２３に進むのは、フラッシュ光による測距演算結果と、投光ＬＥＤによる測距演算結果の両方がＮＧであった場合である。この場合にはステップＳ１２３において、両方の測距におけるコントラストが比較される。フラッシュ補助光のコントラストの方が大きい場合（Ｓ１２３：ＹＥＳ）、フラッシュ補助光フラグが“１”にセットされる。投光ＬＥＤによるコントラストの方が大きい場合には（Ｓ１２３：ＮＯ）、投光ＬＥＤフラグが“１”にセットされる。次に、ステップＳ１１８において、サーチ駆動処理中に用いられるフラグがセットされた後、ステップＳ１３７以降のサーチ駆動処理が開始される。
【００４７】
エリアＡＦモード（Ｓ１１３：ＹＥＳ）又はフラッシュ光によるコントラストが所定値以上である（Ｓ１１４：ＹＥＳ）ことにより、フラッシュ光が有効とされる場合を除き、以上説明した図４の処理によって、どちらの補助光による測距結果が有効とされるかは下記表４のように決定される。表４に示されるように、両方測距ＯＫのときは信頼性により決定され、一方が測距ＯＫのときはＯＫの方が有効とされ、両方測距ＮＧのときはコントラストにより決定される。
【００４８】
【表４】

【００４９】
なお、図３のステップＳ１０６においてフラッシュ補助光が許可でない場合（Ｓ１０６：ＮＯ）、フラッシュ補助光を用いることができないので、処理はステップＳ１３０に進み投光ＬＥＤが許可であるか否かが判定される。投光ＬＥＤが許可である場合には（Ｓ１３０：ＹＥＳ）、投光ＬＥＤによる測距結果を有効にするために、投光ＬＥＤフラグが“１”にセットされる（Ｓ１３１）。次に、投光ＬＥＤを照射しながら積分が実行され、ステップＳ１３３において測距演算が実行される。測距演算の結果がＯＫであれば（Ｓ１３４：ＮＯ）、その測距結果にしたがってレンズ駆動すべく、処理はステップＳ１５２へ進む。一方、測距ＮＧである場合には（Ｓ１３４：ＹＥＳ）、ステップＳ１３５において、サーチ駆動処理に用いるフラグが設定される。その後、処理はステップＳ１３７以降のサーチ駆動処理に移る。また、ステップＳ１３０において投光ＬＥＤが許可でない場合にも（Ｓ１３０：ＮＯ）、ステップＳ１３６においてフラグが設定された後、ステップＳ１３７以降のサーチ駆動処理に進む。
【００５０】
なお、図３以降に示す処理で利用される各フラグの意味について以下にまとめて示す。
“フラッシュ補助光”：このフラグが“１”のときフラッシュ補助光による測距結果を有効なものとして扱うべきことを表す。
“投光ＬＥＤ”：このフラグが“１”のとき投光ＬＥＤによる測距結果を有効なものとして扱うべきことを表す。
“サーチ”：このフラグが“１”のときサーチ駆動が実行されることを指示する。
“ＴｏＦａｒ”：このフラグが“１”のとき遠距離側へレンズ駆動すべきことを表す。
“ＴｏＮｅａｒ”：このフラグが“１”のとき近距離側へレンズ駆動すべきことを表す。
“ＩＮＶＤＲＶ”：焦点調節レンズ５２が端点にまで達したときに、さらに駆動方向を反転して駆動させるか否かを指示するために用いられる。このフラグが“１”のとき、反転駆動しないことを表す。
【００５１】
ステップＳ１０３（図３）において測距結果ＯＫである場合、ステップＳ１３４（図３）において測距結果ＯＫである場合、ステップＳ１１７（図４）においてフラッシュ補助光測距がＯＫである場合、ステップＳ１２８においてフラッシュ補助光フラグがセットされる場合、又はステップＳ１２９において投光ＬＥＤフラグがセットされる場合は、いずれかの又は両方の補助光により有効なデフォーカス量が得られた場合である。これらの場合には、得られたデフォーカス量にしたがってレンズ駆動すべく、処理はステップＳ１５２（図６）に移る。
【００５２】
図６のステップＳ１５２において、測距結果が確認される。ここで測距ＮＧである場合には、処理はステップＳ１４８に戻る。なお、ステップＳ１０３、Ｓ１３４、Ｓ１１７、Ｓ１２８、又はＳ１２９からここに移ってくる場合には、基本的に測距結果はＯＫである。ステップＳ１５２において測距ＯＫである場合には、測距演算の結果のデフォーカス量が合焦幅内であるか否かが判定される。なお、ここで用いられるデフォーカス量は、有効となっている補助光による測距結果または補助光を用いない測距結果としてのデフォーカス量である。合焦幅にない場合には（Ｓ１５３：ＮＯ）、ステップＳ１５４及びＳ１５５において合焦点の位置が確認される。
【００５３】
被写体像の合焦点がフィルム面等価位置よりも遠距離側にある場合には（Ｓ１５４：ＹＥＳ）、ＴｏＦａｒフラグがセットされ（Ｓ１５８）、処理はステップＳ１６０のＡＦモータ駆動処理に進む。ステップＳ１６０では、有効なデフォーカス量にＫバリューを乗じて得た駆動量にしたがって（この場合遠距離側に向かって）、焦点調節レンズ５２が駆動される。被写体像の合焦点が遠距離側でなく近距離側にある場合には（Ｓ１５５：ＹＥＳ）、ＴｏＮｅａｒフラグがセットされ（Ｓ１５９）、処理はステップＳ１６０のＡＦモータ駆動処理へ進む。ステップＳ１６０では、有効なデフォーカス量にＫバリューを乗じて得た駆動量にしたがって（この場合近距離側に向かって）、焦点調節レンズ５２が駆動される。
【００５４】
ステップＳ１６０で呼び出されるＡＦモータ駆動サブルーチンの詳細を図８に示す。図８に示すように、ステップＳ２０１では、有効なデフォーカス量に基づいて駆動パルス数が設定される。次に、レンズ駆動方向が確認され、遠距離側への駆動である場合には（Ｓ２０２：ＹＥＳ）、遠距離側に向けての駆動が開始される。一方、ステップＳ２０３において近距離側に向けての駆動であると判定される場合には、ステップＳ２０５において近距離側に向けての駆動が開始される。ステップＳ２０４又はＳ２０５の処理の後、本サブルーチンは終了する。なお、レンズの駆動方向が得られなかった場合には（Ｓ２０３：ＮＯ）、処理はステップＳ１４８に移る。なお、ＣＰＵ２０は、ステップＳ２０１において設定されたレンズ駆動パルスを、実際にレンズ駆動されたパルス数にしたがってダウンカウントする処理を開始する。ステップＳ２０４又はＳ２０５の処理の後、サブルーチンは終了し、処理は図７のステップＳ１６１に進み、オーバーラップ処理が実行される。（割り込み処理）
【００５５】
なお、図６のステップＳ１５３で合焦であると判定される場合には、処理はステップＳ１５６に進み、フラッシュズーム復帰処理が実行される。次に、カメラ本体１０の設定が、一度ピントが合うとその状態を維持するＡＦロックである場合には（Ｓ１５７：ＹＥＳ）、そのままループする。そうでない場合には（Ｓ１５７：ＮＯ）、処理はステップＳ１５１に戻る。
【００５６】
ステップＳ１５６のフラッシュズーム復帰処理サブルーチンの詳細が図１１に示される。フラッシュズーム復帰処理では、始めにステップＳ４１４において、撮影レンズ５０側から焦点距離の情報が取得される。次に、ステップＳ４１５において、取得した焦点距離が、変数‘Z’に格納される。次に、‘Z’にしたがってフラッシュズームデータが設定され（Ｓ４１２）、設定されたフラッシュズームデータがフラッシュ装置８０側に送信される（Ｓ４１３）。そして、所定のウェイト処理（Ｓ４１４）の後、サブルーチンは終了する。したがって、フラッシュズーム復帰処理によって、フラッシュ装置８０内の発光部ユニット８２の位置は、ＡＦモードにしたがったズーム位置ではなく、撮影レンズ５０の焦点距離に対応するズーム位置に移動される。すなわち、フラッシュ撮影の準備が整う。
【００５７】
図７は、レンズ駆動しながら積分及び測距演算を行って、レンズ駆動パルス数を最新の測距結果に基づいて更新して行くオーバーラップ処理を表している。図７に示すように、ステップＳ１６１では、補助光を用いることなく、積分及び測距演算が実行される。ステップＳ１６２において、ステップＳ１６１での測距演算結果が確認される。有効なデフォーカス量が得られず測距ＮＧである場合には（Ｓ１６２：ＹＥＳ）、ステップＳ１６１の処理が繰り返される。測距ＯＫである場合には（Ｓ１６２：ＮＯ）、次に、被写体像の合焦点の位置が判定される。
【００５８】
被写体像の合焦点が遠距離側にあると判定される場合には（Ｓ１６３：ＹＥＳ）、ＴｏＦａｒフラグの値が確認される。ＴｏＦａｒフラグが“１”であり、合焦点の方向である遠距離方向にレンズが向かっている場合には（Ｓ１６７：ＹＥＳ）、レンズ駆動パルスが、ステップＳ１６１における最新の測距結果に基づいて更新され（Ｓ１６５）、ステップＳ１６１からのオーバーラップ処理が繰り返される。また、ステップＳ１６４において被写体像の合焦位置が近距離側にあり（Ｓ１６４：ＹＥＳ）、レンズ駆動方向も近距離側である場合にも（Ｓ１６６：ＹＥＳ）、レンズ駆動パルスがステップＳ１６１における最新の測距結果に基づいて更新され（Ｓ１６５）、Ｓ１６１からのオーバーラップ処理が繰り返される。
【００５９】
ステップＳ１６７において、レンズ駆動方向が合焦点の方向と反対方向であると判定されるのは（Ｓ１６７：ＮＯ）、焦点調節レンズ５２が行き過ぎになった場合である。ステップＳ１６６において、ＴｏＮｅａｒフラグが“１”でない場合（Ｓ１６６：ＮＯ）も同様に焦点調節レンズ５２が行き過ぎになった場合である。これらの場合は、レンズ駆動を停止すべく処理はステップＳ１４８に戻る。
【００６０】
図６において、ステップＳ１４８ではスタックがクリアされる。次にステップＳ１４９においてＡＦモーター２３が停止される。さらに、ステップＳ１５０において、各フラグがクリアされる。次にステップＳ１５１において、補助光を用いることなく、通常の外光による積分及び測距演算が実行された後、この測距結果に基づいてレンズ駆動を開始すべく、処理はステップＳ１５２に進む。
【００６１】
次に、図５を参照してサーチ駆動動作について説明する。ステップＳ１３５，Ｓ１３６，又はＳ１１８の次に実行されるステップＳ１３７からの処理が、サーチ駆動処理である。サーチ駆動処理では、設定されているフラグにしたがって、焦点調節レンズ５２を端点に達するまで移動させながら、測距演算ＯＫとなるまで測距演算が繰返し実行される。
【００６２】
ステップＳ１３７では、焦点調節レンズ５２が、現在位置から近距離側又は遠距離側の端部まで確実に到達できるだけの駆動パルス数が設定される。ステップＳ１３８では、設定された駆動パルス数にしたがってレンズ駆動が開始される。ステップＳ１３９では、通常の外光による積分及び測距演算が実行される。その結果、有効なデフォーカス量が得られ、合焦点が遠距離側にあると判定される場合には（Ｓ１４０：ＹＥＳ）、ステップＳ１４５において、レンズ駆動の方向が確認される。レンズ駆動の方向が合焦点のある方向と同じく遠距離側である場合には（Ｓ１４５：ＹＥＳ）、ステップＳ１３９で求められた測距結果に基づくパルス数で駆動パルスが更新される（Ｓ１４６）。次に、ステップＳ１４７においてサーチフラグがクリアされ、オーバーラップ処理を行うべく、処理はステップＳ１６１に移る。ステップＳ１４５において、レンズ駆動方向が遠距離側でない場合には（Ｓ１４５：ＮＯ）、焦点調節レンズ５２が行き過ぎとなっている場合であり、レンズ駆動を停止すべく、処理はステップＳ１４８に移る。
【００６３】
合焦点が近距離側にあると判定される場合には（Ｓ１４１：ＹＥＳ）、ステップＳ１４４においてレンズ駆動の方向が確認される。レンズ駆動の方向が合焦点のある方向と同じく近距離方向である場合には（Ｓ１４４：ＹＥＳ）、ステップＳ１３９で求められた測距結果に基づくパルス数で駆動パルスが更新される（Ｓ１４６）。次に、ステップＳ１４７においてサーチフラグがクリアされ、オーバーラップ処理を行うべく、処理はステップＳ１６１に移る。ステップＳ１４４において、レンズ駆動方向が近距離側でない場合には（Ｓ１４４：ＮＯ）、焦点調節レンズ５２が行き過ぎとなっている場合であり、レンズ駆動を停止すべく、処理はステップＳ１４８に移る。
【００６４】
ステップＳ１４２において有効なデフォーカス量が得られ、合焦であると判定される場合には（Ｓ１４２：ＹＥＳ）、レンズ駆動を停止すべく、処理はステップＳ１４８に移る。
【００６５】
ステップＳ１４２において合焦でないと判定される場合には（Ｓ１４２：ＮＯ）、ステップＳ１３９における測距演算の結果が確認される（Ｓ１４３）。演算ＮＧである場合には（Ｓ１４３：ＹＥＳ）、サーチ駆動を続行すべく、処理はステップＳ１３９に戻る。なお、ステップＳ１４３において演算ＯＫである場合には、処理はステップＳ１４８に移る。
【００６６】
図９は、焦点調節レンズ５２を駆動すべきパルス数分の駆動が終了した場合（ダウンカウント値が０に到達した場合）に呼び出される割り込み処理のフローチャートである。ずなわち、合焦位置までのレンズ駆動が終了すると、図９の割り込みルーチンが起動される。
【００６７】
図９において、始めにＡＦモータ２３が停止される（Ｓ３０１）。次に、ステップＳ３０２〜Ｓ３０９の処理によって、焦点調節レンズ５２の駆動が終了した状態で、もう一度確認のために焦点検出が行われる。このとき、最初に補助光を用いている場合には、最初に用いた方の補助光が発光される。すなわち、ステップＳ３０２において、フラッシュ補助光フラグが“１”である場合には、最初の測距において、フラッシュ光による測距結果が有効なものとして決定されている場合には、ここでも補助光としてフラッシュ光を用いて積分が行われる（Ｓ３０８）。その後、処理はステップＳ３０５に移り、各フラグがクリアされスタックもクリアされた後（Ｓ３０５、Ｓ３０６）、測距演算が実行される（Ｓ３０７）。
【００６８】
最初の測距において、投光ＬＥＤによる測距結果が有効とされている場合には（Ｓ３０３：ＹＥＳ）、ここでも投光ＬＥＤを発光させて積分が実行される（Ｓ３０９）。その後、処理はステップＳ３０５に進む。補助光が用いられていないときには（Ｓ３０３：ＮＯ）、補助光を用いることなく積分が実行され（Ｓ３０４）、その後処理はステップＳ３０５に進む。ステップＳ３０７において測距演算が実行された後、処理はステップＳ１５２以降の処理に進むが、合焦点まで駆動された後なので、基本的にはステップＳ１５３において合焦であると判定されることになる。以上のように、図９の処理によって、レンズ駆動停止後、再度焦点検出され必要な場合にはレンズ駆動されるので、ＡＦ精度が向上する。このとき、投光ＬＥＤフラグ又はフラッシュ補助光フラグがセットされ、有効とされている補助光が用いられるので、確実に焦点検出が行われることになる。
【００６９】
図１０は、焦点調節レンズ５２が遠距離側又は近距離側の端点に達した場合に実行される割り込み処理を表すフローチャートである。すなわち、図１０の端点検出割り込みルーチンは、サーチ駆動処理等により焦点調節レンズ５２が駆動されているときに、焦点調節レンズ５２がその移動範囲の端点に到達した場合に起動される。
【００７０】
図１０の端点検出割り込み処理ルーチンにおいて、始めにステップＳ３５１において所定のリミット時間内に、ＡＦモーター２３の駆動パルス数が所定値以上となるか否かが確認される。所定値以上のパルス数である場合には（Ｓ３５１：ＹＥＳ）、割り込み処理は終了する。パルス数が所定値に達しない場合には（Ｓ３５１：ＮＯ）、ステップＳ３５２以降の処理に進む。ステップＳ３５２において、ＡＦモータ２３が停止される。次に、スタックがクリアされ、リミットフラグがセットされる（Ｓ３５３、Ｓ３５４）。次に、サーチフラグが“１”であるか否かが判定される。サーチフラグがセットされていない場合（Ｓ３５５：ＮＯ）、処理はステップＳ１４８（図６）に移る。
【００７１】
一方、サーチフラグがセットされている場合には（Ｓ３５５：ＹＥＳ）、ＩＮＶＤＲＶフラグの値にしたがって、レンズ駆動方向を反転させるか否かが決定される。
【００７２】
ステップＳ３５６では、焦点調節レンズ５２が端点にある状態で測距演算が行われる。ここで演算ＯＫとなった場合には（Ｓ３５７：ＮＯ）、各フラグがクリアされた後（Ｓ３６４）、レンズ駆動すべく、処理はステップＳ１５２に移る。測距ＮＧである場合には（Ｓ３５７：ＹＥＳ）、ステップＳ３５８においてＩＮＶＤＲＶフラグの値が確認される。ステップＳ１３５及びステップＳ１１８に示されているように、補助光を用いた測距では遠距離側の方が測距点が求まり易いため近距離側にはあえて駆動（反転）せず、処理はステップＳ３６５に進む。
【００７３】
ステップＳ３６５において、フラッシュ補助光フラグを確認することにより、最初に用いた補助光がフラッシュ光である場合には（Ｓ３６５：ＹＥＳ）、フラッシュ補助光を発光して積分が実行される（Ｓ３６８）。次に、３メートルの被写体距離の位置で焦点調節レンズ５２を停止させるべくパルス計算が行われ（Ｓ３７０）、ＴｏＮｅａｒフラグがセットされ（Ｓ３７１）処理はステップＳ１３８に進む。最初に用いた補助光が投光ＬＥＤである場合には（Ｓ３６６：ＹＥＳ）、投光ＬＥＤを発光して積分が実行される。その後処理はステップＳ３７０に進む。一方、補助光が用いられていない場合には（Ｓ３６６：ＮＯ）、各フラグがクリアされ（Ｓ３６７）、処理はステップＳ１４８に移る。
【００７４】
一方ステップＳ３５８おいてＩＮＶＤＲＶが“１”でない場合には（Ｓ３５８：ＮＯ）、レンズ駆動方向を反転してサーチ駆動を続行する為の処理が行われる。ステップＳ１３６（図３）からサーチ駆動処理に入り、最初に端点検出された場合には、ＩＮＶＤＲＶ＝０である。この場合には、反転駆動が行われることになる。
【００７５】
ステップＳ３５９において、近距離側の端点（Ｎリミット）であると判定される場合には（Ｓ３５９：ＹＥＳ）、ＴｏＦａｒフラグ、ＩＮＶＤＲＶフラグがセットされ（Ｓ３６１、Ｓ３６３）、処理はステップＳ１３７に進む。すなわち、遠距離端点側に向けてサーチ駆動が続行される。なお、次に端点検出されたとき、駆動方向を反転してサーチ駆動されることがないように、ＩＮＶＤＲＶフラグがセットされる。一方、端点が遠距離側（Ｆリミット）である場合には（Ｓ３６０：ＹＥＳ）、ＴｏＮｅａｒフラグ、ＩＮＶＤＲＶフラグがセットされ（Ｓ３６２、Ｓ３６３）、処理はステップＳ１３７に進む。すなわち、近距離端点側に向けてサーチ駆動が続行される。なお、ステップＳ３６０においてＦリミットでもない場合には、処理はステップＳ１０１に戻る。
【００７６】
以上説明した本発明の実施形態としてのフローチャートにおける全ての要素が、本発明のオートフォーカス装置を実現する上で必要なわけではなく、様々に変形することができる。例えば、フラッシュ補助光と投光ＬＥＤを発光させる順番を入れ替えることもできる。また、ステップＳ１０７（図３）のフラッシュズーム変更処理において、発光部ユニットがズーム駆動されることは必ずしも必要ではなく、固定の照射角であっても良い。また、図９において説明した再発光処理が省略された形の実施形態も有り得る。
【００７７】
【発明の効果】
以上説明したように本発明によれば、被写体のコントラスト、ＡＦモード、及び測距結果のような諸条件にしたがって最適な補助光が利用され、すなわち、それぞれの補助光の特長が的確に引き出され、補助光を用いる場合のＡＦ精度が向上される。
【図面の簡単な説明】
【図１】本発明のフラッシュ補助光システムを適用したカメラシステムの制御系のブロック図である。
【図２】図１のカメラシステムの撮影画面内における焦点検出エリアの配置を示す図である。
【図３】図４〜図７とともに、ＡＦ処理を表すフローチャートである。
【図４】図３、及び図５〜図７とともに、ＡＦ処理を表すフローチャートである。
【図５】図３、図４、図６、及び図７とともに、ＡＦ処理を表すフローチャートである。
【図６】図３〜図５、及び図７とともに、ＡＦ処理を表すフローチャートである。
【図７】図３〜図６とともに、ＡＦ処理を表すフローチャートである。
【図８】ＡＦモータ駆動処理サブルーチンのフローチャートである。
【図９】駆動パルスがダウンカウントされて０となった場合に実行される割り込み処理のフローチャートである。
【図１０】焦点調節レンズが端点に到達した場合に実行される端点検出割り込み処理のフローチャートである。
【図１１】フラッシュズーム変更処理サブルーチンのフローチャートである。
【図１２】フラッシュ補助光＆積分処理サブルーチンのフローチャートである。
【符号の説明】
２ メインミラー
３ サブミラー
４ ペンタプリズム
５ 測光ＩＣ
６ ＣＣＤセンサユニット
１０ カメラ本体
１２ 周辺部制御回路
２０ ＣＰＵ
２３ ＡＦモーター
５０ 撮影レンズ
５２ 焦点調節レンズ
５４ レンズ制御部
８０ フラッシュ装置
８１ フラッシュ制御回路
８２ 発光部ユニット
８５ 投光ＬＥＤ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an autofocus device using auxiliary light.
[0002]
[Prior art]
In an autofocus camera using a passive type focus detection method, AF auxiliary light is used so that focus detection is performed even for a low-luminance subject. As such AF auxiliary light, for example, there is a light projection LED that uses an LED as a light source and projects a contrast pattern onto a subject.
[0003]
For example, as disclosed in Japanese Patent Laid-Open No. 5-34577, there has been proposed one that uses flash light of a flash device as auxiliary light during AF operation.
[0004]
[Problems to be solved by the invention]
Since the projection LED projects a contrast pattern onto the subject, it is particularly effective when the subject has a low contrast, but it may not be effective for a subject with contrast. In addition, since the contrast pattern is projected, it is difficult to construct a contrast pattern that is compatible with each AF sensor in the case of multi-point AF and the like, and satisfies the irradiation pattern at the same time, and thus the irradiation range is limited. Auxiliary light from flash light is not effective for low-contrast subjects, but is effective for high-contrast subjects. It is also effective in the mode. Further, since a flash device used for photographing can be used as it is, no special device is required. As described above, each of the light emitting LED and the flash light has a feature. However, there is no known autofocus device that can accurately extract the features of each auxiliary light and improve the AF accuracy.
[0005]
The present invention has been made in view of such circumstances. That is, an object of the present invention is to provide an autofocus device capable of accurately extracting the features of the auxiliary light of each of the flash device and the light projecting LED and improving the accuracy of the AF operation.
[0006]
[Means for Solving the Problems]
Therefore, the invention described in claim 1 includes a flash device that emits flash light and a light emitting LED that emits a light projection pattern as auxiliary light during AF (autofocus) operation. An autofocus device that performs lens drive control based on a detection result, and first detects a focus by emitting flash light, and if the contrast of a subject image by the flash light is equal to or greater than a predetermined value, the focus detection result by the flash light If the contrast is not equal to or greater than the predetermined value, the projection LED is then turned on to detect the focus, and the more reliable focus detection result of each auxiliary light is selected. And a control means for performing lens drive control based on the selected focus detection result. If the subject has contrast, there is a high possibility that a highly accurate AF operation can be achieved by performing focus detection based on the original contrast of the subject. Therefore, only flash light is used if the contrast is equal to or greater than a predetermined value. However, when the contrast of the subject is not equal to or greater than the predetermined value, it is necessary to determine which of the auxiliary light focus detection results is appropriate based on the focus detection result of each auxiliary light. On the other hand, in the focus detection by the phase difference method, the reliability of the focus position detection result is usually required based on the correlation calculation result. Therefore, when the contrast is not greater than or equal to the predetermined value, the more reliable focus detection result is selected.
[0007]
According to a second aspect of the present invention, there is provided an autofocus device having a flash device that emits flash light as auxiliary light at the time of AF (autofocus) operation, and a light projection LED that projects a light projection pattern. Focus detection means for performing focus detection based on the above, and when auxiliary light is required, the flash device and the light emitting LED are sequentially emitted in either order, and the focus detection means emits auxiliary light to detect the focus And the following rules (1), (2), and (3) based on the light emission control means for performing each of the above and the focus detection result obtained by the control operation of the light emission control means:
(1) When the contrast of the subject image by the flash light is a predetermined value or more, the focus detection result by the flash light is validated.
(2) The focus detection result that is not in focus detection NG (a valid defocus amount cannot be obtained) is validated.
(3) When both of the focus detection results by the auxiliary light are focus detection OK (an effective defocus amount is obtained), the more reliable focus detection result is validated.
The rule (1) is applied with priority, a decision unit that determines which of the auxiliary light is used as the focus detection result is valid, and the focus adjustment lens is driven and controlled based on the focus detection result that is validated by the decision unit Lens drive control means. If the subject has contrast, there is a high possibility that a highly accurate AF operation can be achieved by performing focus detection based on the original contrast of the subject. Therefore, the decision means applies rule (1), and if the subject image contrast by the flash light is equal to or greater than a predetermined value, the focus by the flash light is driven so that the focus adjustment lens is driven based on the focus detection result by the flash light. Enable detection results. Further, according to the rule (2), when the focus detection result by any one of the auxiliary lights does not obtain an effective defocus amount and the focus detection is NG, the determination means determines the auxiliary light that is the focus detection NG. The focus result that is the focus detection OK is made valid so that the focus detection result by is not used. In focus detection by the phase difference method, reliability of the focus position detection result is usually required based on the result of correlation calculation. Therefore, when both the focus detection results by the auxiliary light are OK and it is necessary to select the focus detection result by one of the auxiliary lights, it is appropriate to select the one with higher reliability. Therefore, the determination unit validates the focus detection result with higher reliability according to the rule (3) when both the focus detection results using the auxiliary light are OK. Since rule (1) is prioritized, if both are OK and the contrast by the flash light is a predetermined value or more, the focus detection result by the flash light is valid.
[0008]
According to a third aspect of the present invention, the light emission control means causes the flash light to be emitted first and causes the focus detection means to perform focus detection, and the determination means determines when the focus detection result by the flash light is obtained. The determination is made based only on the rule (1), and when the contrast by the flash light is a predetermined value or more, the light emitting LED is not emitted. If the subject has contrast, there is a high possibility that a highly accurate AF operation can be achieved by performing focus detection based on the original contrast of the subject. Therefore, only the flash light is used if the contrast by the flash light is not less than a predetermined value.
[0009]
In the invention according to claim 4, when the focus adjustment lens is driven to the in-focus position, the auxiliary light which is considered to be effective is emitted again to perform focus detection, and The apparatus further includes re-light emitting means for driving the lens by the lens drive control means based on the focus detection result. Once the focus adjustment lens is driven to the in-focus position, focus detection is performed again by emitting auxiliary light, and it is confirmed whether or not the in-focus state is achieved. At this time, since the auxiliary light determined to be effective when the focus is first detected is used, focus detection for confirmation is surely executed.
[0010]
According to the fifth aspect of the present invention, when both of the focus detection results by the auxiliary light are the focus detection NG, the lens driving means drives the focus adjustment lens until it reaches the far end of the moving range. The focus detection unit further includes a search drive control unit that performs focus detection and stops lens driving when the focus is achieved, and the determination unit determines the auxiliary light used by the re-emission unit at the time of re-emission. If both (4) and (4) are focus detection NG, the one with the higher contrast of the subject image is valid.
Apply. When the light is focused by the search driving operation and then the light emission for confirming whether it is in focus by the re-emission means, the higher contrast in the first focus detection, that is, the higher the possibility of focus detection Since auxiliary light is used, focus detection for confirmation is surely executed.
[0011]
In the invention according to claim 6, the AF mode is not a spot AF mode in which a spot at the center of the shooting screen is an AF target, but an area AF mode in which an area wider than the spot AF mode is an AF target. In this case, the light emission control unit emits only the flash light, and the determination unit validates the focus detection result by the flash light regardless of the respective rules. In the area AF mode, since a wide irradiation angle is required, only flash light is emitted, and lens driving is performed based on the focus detection result obtained thereby.
[0012]
The invention described in claim 7 includes a flash device that emits flash light as auxiliary light during AF (autofocus) operation, and a light projection LED that emits a light projection pattern, and focus detection using any of the auxiliary lights. An autofocus device that performs lens drive control based on a result, and the AF mode is not a spot AF mode that targets a spot at the center of the shooting screen as an AF target, but an area AF that targets an area wider than the spot AF mode. In the case of the mode, control means for controlling lens driving based on the focus detection result by the flash light is provided. In the area AF mode in which a wide area in the photographing screen is an AF target, it is suitable to use flash light that can cover a wide irradiation angle. Therefore, flash light is used in the area AF mode.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a control system of a camera system 100 to which an autofocus device of the present invention is applied. The camera system 100 includes a camera body 10, a photographing lens (interchangeable lens) 50 attached via a lens mount of the camera body 10, and a flash device 80 attached via a contact shoe of the camera body 10. . The camera system 100 is an AF single-lens reflex camera, and has a plurality of focus detection areas in a shooting screen, and can perform multipoint automatic focus adjustment. The CPU 20 is a CPU that performs various controls of the camera system 100, and is also a focus detection unit that performs focus detection by the phase difference method together with the CCD sensor unit 6. Either the projection LED 85 or the light emitting unit 82 (flash light) is used. It is also a means for determining whether or not the focus detection result is valid, and is a means for driving the focus adjustment lens 52 by giving a drive pulse to the AF motor 23.
[0014]
In FIG. 1, most of the light rays from the subject that pass through the focus adjustment lens 52 in the photographing lens 50 and enter the camera body 10 are reflected by the main mirror 2, transmitted by the pentaprism 4, and reflected by the eyepiece. The light is emitted from (not shown) and guided to the light receiving surface of the photometric IC 5. For example, the photometry IC 5 generates an electric signal obtained by logarithmically compressing a voltage value corresponding to the amount of received light, and provides information related to the amount of received light to the CPU 20 via the peripheral control circuit 12. The CPU 20 executes AE calculation (exposure calculation) based on the received light amount information and film sensitivity information obtained from the photometry IC 5 and calculates an appropriate shutter speed and an appropriate aperture value for photographing. During the photographing process, the CPU 20 controls the exposure mechanism 16 and the aperture mechanism 17 based on the calculated appropriate shutter speed and the appropriate aperture value via the peripheral control circuit 12 to perform exposure on the film. Further, the CPU 20 drives the mirror motor 14 via the motor driver IC 13 and controls the main mirror 2 up / down in the photographing process via the peripheral control circuit 12, and controls the main mirror 2 after the exposure is completed. To drive the film up by one frame. Further, the CPU 20 displays various information related to photographing on the display unit 21 that is a display unit on the camera exterior surface or a display unit in the viewfinder.
[0015]
On the other hand, the main mirror 2 is provided with a half mirror portion (not shown), and the light beam transmitted through the main mirror 2 is reflected by the sub mirror 3 and guided to the CCD sensor unit 6. The CCD sensor unit 6 is a sensor unit for performing focus detection by a phase difference method. A CCD line sensor is disposed in the CCD sensor unit 6 at a position conjugate with the film surface. The subject image enters a pair of CCD sensors in the CCD line sensor, accumulates (integrates) a predetermined amount of charge, is photoelectrically converted, and is transmitted to the CPU 20 via the peripheral control circuit 12 as an electrical signal. The CPU 20 calculates the defocus amount based on signals obtained from the pair of CCD sensors.
[0016]
Based on the defocus amount, the CPU 20 obtains the rotation direction and the number of rotations of the AF motor 23 for driving the focus adjustment lens 52 and performing focus adjustment, and drives and controls the AF motor 23 via the motor driver IC 22. . The rotation of the AF motor 23 is transmitted to the lens control unit 54 of the photographing lens 50 via the joint 26 provided in the lens mount unit of the camera body 10, whereby the focus adjustment lens 52 reaches the in-focus position in the optical axis direction. It is driven back and forth.
[0017]
The lens control circuit 54 in the photographic lens 50 and the peripheral control circuit 12 in the camera body 10 are electrically connected to each other via the lens side contact terminal 55, the lens contact terminal 29, and the signal line 25. Information regarding the photographic lens 50 is transmitted from the photographic lens 50 to the camera body 10 via the signal line 25. The information transmitted by the lens control circuit 54 includes, for example, the focal length of the photographing lens 50, the wide open aperture Av (the apex converted value of the full open F value), the maximum aperture value Av (the apex converted value of the minimum aperture F value), and the K value. There are data. The K value is the number of driving pulses of the AF motor 23 required to move the image plane formed by the photographing lens 50 by a unit length in the optical axis direction.
[0018]
In the flash device 80, the light emitting unit 82 is made of a xenon tube or the like. A light projecting lens 87 is provided in front of the light emitting unit 82. The light emitting unit 82 is provided so as to be movable in the optical axis direction with respect to the light projecting lens 87. By changing the distance from the light projecting lens 87, the irradiation angle of the flash light can be changed. The flash controller 81 is electrically connected to the peripheral control circuit 12 on the camera body 10 side via the signal line 24, the flash side connection terminal 86, and the flash connection terminal 28 on the camera body side. The flash control circuit 81 grasps the position of the light emitting unit 82 by a position detection mechanism (not shown) including a code plate provided along the moving direction of the light emitting unit 82 and a brush attached to the light emitting unit 82. When the flash zoom data indicating the zoom position of the light emitting unit 82 is sent from the peripheral control circuit 12, the flash control circuit 81 drives and controls the zoom motor 83 via the driver IC 84. Then, the light emitting unit 82 is driven back and forth to the zoom position corresponding to the flash zoom data. When the light emitting unit 82 is zoom-driven in a direction approaching the light projection lens 87, the irradiation angle is widened, and when the zoom driving is performed in a direction away from the light projection lens 87, the irradiation angle is narrowed. Further, the flash control unit 81 causes the light emitting unit 82 to emit light when a light emission instruction is sent via the signal line 24. By illuminating the light emitting unit 82, the irradiation angle of the flash light is adjusted. The light emitting unit 82 in the flash device 80 emits flash light toward the subject at the time of shooting, and is also used to emit auxiliary light in the AF operation of the camera system 100 as described below.
[0019]
Further, the flash device 80 includes a light projection LED 85 that projects a contrast pattern not only to the flash light but also to the subject as AF auxiliary light. The projecting LED 85 includes a visible light emitting diode that emits visible light and a projection optical system.
[0020]
In the camera system 100 of FIG. 1, a CPU 20 is connected to a photometric switch 31 that is turned on when a release button (not shown) is half-pressed and a release switch 32 that is turned on when the release button is fully pressed. An arithmetic operation and an AF operation are executed, and a shooting operation is executed when the release switch 32 is turned on. Furthermore, an AF mode setting switch 33 is connected to the CPU 20, and the user operates the AF mode setting switch 33 to set the AF mode for the CPU 20 before shooting. Examples of the AF mode that can be controlled by the CPU 20 include a spot AF mode, a wide AF mode, a center three-point AF mode, and a user selection AF mode. The spot AF mode is a mode in which automatic focus adjustment is performed using only the focus detection area at the center of the shooting screen among a plurality of focus detection areas. FIG. 2 shows the arrangement of the focus detection areas in the shooting screen 88 (that is, in the viewfinder) of the camera system 100. As shown in FIG. 2, each focus detection area is arranged in six parts: a central area C, an upper area CC, areas R and L on both sides of the area C, and peripheral areas LL and RR. Yes. In the spot AF mode, area C is an AF target.
[0021]
In the wide AF mode, subject images are detected in all focus detection areas, one focus detection area is selected according to a predetermined selection algorithm, and the lens is focused on the subject in the selected focus detection area. This is an AF mode in which drive control is performed. In the center three-point AF mode, a subject image is detected in three focus detection areas (for example, L, R, and C) in the center, and one focus detection area is selected from the three focus detection areas according to a predetermined algorithm. AF mode in which lens drive control is performed so that the subject in the selected focus detection area is focused. The AF mode also includes a user selection AF mode in which the user selects an arbitrary focus detection area as the AF target area.
[0022]
3 to 7 represent AF processing executed by the CPU 20 of the camera system 100. These AF processes are started by pressing the release button of the camera system 100 halfway.
[0023]
As shown in FIG. 3, when the AF process is started, first, in step S101, each flag used in the AF process is cleared. Next, in step S102, a predetermined amount of light from the subject is accumulated (integrated) in the CCD sensor unit 6 and a defocus amount of the subject image is calculated (ranging calculation). In the distance calculation processing, when the AF mode is the wide AF mode or the central three-point AF mode, a focus detection area that is a target for obtaining the number of drive pulses for driving the focus adjustment lens 52 according to a predetermined algorithm. Is selected. In the distance calculation processing, in addition to the defocus amount calculation, the subject contrast is obtained as a numerical value by a predetermined arithmetic expression based on the video signal from the CCD sensor unit 6, and is the subject contrast equal to or higher than the predetermined value? A contrast determination process is also executed to determine whether the contrast is NG if it is less than a predetermined value. Hereinafter, it is assumed that the contrast detection operation is also performed in the distance calculation operation.
[0024]
In step S103, the result of the distance measurement calculation is confirmed. If an effective defocus amount is obtained as a result of the distance measurement calculation (S103: NO), the process proceeds to step S152, and lens driving based on the obtained defocus amount is started. If the effective defocus amount cannot be obtained and the distance measurement is NG (S103: YES), the cause is determined in steps S104 and S105. In step S104, it is determined whether or not the brightness is low. In step S105, it is determined whether or not the contrast is NG due to low contrast. When the brightness is not low or the contrast is not NG (S104: NO or S105: NO), the search drive is executed by the processing after step S136. In the case of low brightness and contrast NG (S105: YES), an AF operation using auxiliary light is executed in the processing after step S107.
[0025]
In step S106, it is determined whether or not the flash auxiliary light can be used. This determination processing is performed, for example, when the flash device 80 is mounted on the camera body 10 so that the flash control unit 81 can communicate with the CPU 20 via the peripheral control circuit 12 and the light emitting unit 82 emits light. This is performed based on whether charging is completed and light emission is possible. If the flash auxiliary light is usable (S106: YES), a flash zoom change process subroutine, which is a process of zoom driving the light emitting unit 82 in the flash unit 80, is executed in step S107. The flash zoom change process will be described with reference to FIG.
[0026]
In the flash zoom change process, flash zoom data indicating the zoom position of the light emitting unit 82 is determined according to the AF mode, and the flash zoom data is transmitted from the CPU 20 to the flash control unit 81. Table 1 shows the relationship between the flash zoom data determined by the CPU 20 and the zoom position of the light emitting unit 82. As shown in Table 1, when the flash control unit 81 receives a value of 0 as flash data, the flash control unit 81 controls the light emitting unit 82 so that the irradiation angle of the light emitting unit 82 covers the range of the focal length of 24 mm of the photographing lens. Move to the zoom position on the wide side. When the flash control unit 81 receives the value 5 as flash data, the flash control unit 81 moves the light-emitting unit 82 to the telescopic zoom position so that the illumination angle of the light-emitting unit 82 covers the range of the focal length of 85 mm of the photographing lens. Move to. That is, as the value of the flash zoom data is larger, the position of the light emitting unit 82 is further away from the light projecting lens 87 and the irradiation angle is reduced.
[0027]
[Table 1]

[0028]
In FIG. 11, when the flash zoom change subroutine is started, first, in step S401, it is determined whether or not the AF mode is the spot AF mode. If it is spot AF (S401: YES), the focus detection area used for focus detection is only the central area C in the photographing screen 88, and therefore the most zoom position of the light emitting unit 82 is the telephoto side zoom position of 85 mm. Is selected (S403), and it is determined that the flash zoom data has a value of 5 (S412). In step S402, even when the focus detection area selected in the user selection AF mode is the area C or CC, 85 mm which is the zoom position on the most tele side is selected as the zoom position of the light emitting unit 82 ( S412). In area C and area CC, since the focus detection area is limited to the vicinity of the center, the AF auxiliary light can be focused to the center. Therefore, in this case, the zoom position of the light emitting unit 82 is the most telephoto position, and the irradiation angle is reduced to a range sufficient to cover the angle of view of the focal length of 85 mm of the photographing lens. That is, the flash light is prevented from diffusing to a focus detection area that is not used for focus detection.
[0029]
If the spot AF mode is not set and the area selected by the user is neither C nor CC (S402: NO), it is determined in step S404 whether or not the AF mode is the wide AF mode. In the wide AF mode (S404: YES), in step S406, the zoom position of the widest side, 24 mm, is selected as the zoom position of the light emitting unit 82. In step S405, when the focus detection area selected by the user-selected AF mode is the area LL or RR (S405: YES), the widest zoom position of 24 mm is set as the zoom position of the light emitting unit 82. When selected (S406), the zoom position of the light emitting unit 82 is set to the widest position, and irradiation is performed with a wide irradiation angle that covers the field angle of the focal length of 24 mm of the photographing lens. That is, the focus detection area close to the end of the shooting screen 88 is configured to irradiate the subject at as wide an angle as possible so that the auxiliary light can effectively reach and illuminate the subject.
[0030]
If it is not the wide AF mode and if the area selected by the user is neither LL nor RR (S405: NO), it is determined in step S407 whether or not the AF mode is the central three-point AF mode. In the case of the central three-point AF mode (S407: YES), the value (variable “Z”) to be set in the flash zoom data in step S409 is the focal length of the taking lens 50 (when the taking lens is a zoom lens). Is a value obtained by adding 3 to the value of the flash zoom data corresponding to the current focal length. When the result of addition in step S409 exceeds 5, that is, when the value corresponding to the most tele side of the light emitting unit 82 is exceeded (S410: YES), the value of “Z” is the maximum as flash zoom data. The value is 5. That is, since the AF target area is located near the center of the shooting screen 88, the zoom position of the light emitting unit 82 can be set to the tele side with respect to the focal length of the shooting lens, and the irradiation angle of the auxiliary light can be narrowed down. . Accordingly, in step S409, a value obtained by adding 3 to the flash zoom data corresponding to the focal length of the photographing lens is determined as the flash zoom data. Note that the value of 3 is not limited to this, and other values may be used as long as the flash zoom data covers the focus detection area with a value on the telephoto side relative to the focal length of the photographing lens. good. In step S412, the value determined as the above flash zoom data is set as a variable. Next, the set flash zoom data is transmitted from the CPU 20 to the flash device 80 (S413). In the flash device 80, the light emitting unit 82 is zoom-driven according to the received flash zoom data. Then, after waiting for a predetermined time in step S414, the subroutine ends.
[0031]
Returning to FIG. 3, when the flash zoom change process ends in step S107, the process proceeds to step S108. In step S108, integration processing by irradiating flash auxiliary light is performed. Details of the “flash auxiliary light & integration” subroutine called in step S108 are shown in FIG.
[0032]
In the “flash auxiliary light & integration” process of FIG. 12, the integration process is executed while the flash auxiliary light is emitted. As described below, the light emission amount is controlled according to the zoom position of the light emitting unit 82. The efficiency of light emission is improved. That is, as the position of the light emitting unit 82 is on the tele side, the irradiation angle is narrowed, so that the amount of light emission can be suppressed. Therefore, in the process of FIG. 12, the amount of light emission is suppressed as the value of the flash zoom data is on the tele side. In the process of FIG. 12, the flash light is emitted intermittently. This intermittent light emission is performed according to the light emission time and light emission interval calculated in step S503 and step S504. At this time, in order to avoid that the integrated value of the CCD sensor unit 6 exceeds the allowable range by one light emission and the number of times of light emission increases excessively for the subject, the amount of light emission is stepped according to the number of times of light emission. Control is also performed. Note that the light emission time interval, that is, the charging time is also increased so as to be sufficient for the amount of light emission that increases with the number of times of light emission.
[0033]
In FIG. 12, first, the number of times of light emission is cleared (S501). Next, integration processing in the CCD sensor unit 6 is started (S502). In step S503, the light emission time is determined according to the following definition.
Flash time = Reference flash time + Correction time x (Number of flashes ÷ Number of corrections)
In step S504, the light emission interval is determined according to the following definition.
Flash interval = Reference flash interval + Correction interval x (Number of flashes ÷ Number of corrections)
However, in these equations, (number of times of light emission / number of times of correction) is rounded down to the nearest decimal point.
[0034]
The reference light emission time that defines the first light emission time is determined so as to have the correspondence shown in Table 2 according to the flash zoom data. As shown in Table 2, the reference light emission time is shorter as the zoom position of the light emitting unit 82 is on the telephoto side. Therefore, the light emission amount is reduced as the zoom position of the light emitting unit 82 is on the telephoto side. The table shown in Table 2 is stored in the ROM in the CPU 20, and the CPU 20 reads the table into the RAM in the CPU 20 and uses it.
[0035]
[Table 2]

[0036]
The correction time, the number of corrections, the reference light emission interval, and the correction interval, which are other parameters for determining the light emission time and the light emission interval, are also held in the internal ROM by the CPU 20 as in the case of the reference light emission time. In step S505, processing for causing the light emitting unit 82 to emit light is performed according to the light emission time. In step S506, the number of times of light emission is incremented by one. In step S507, it is determined whether or not a predetermined maximum number of times of light emission has been reached. When the maximum number of times of light emission has been reached (S507: YES), the subroutine ends. If the maximum number of light emission times has not been reached (S507: NO), it is determined in the CCD sensor unit 6 whether or not integration has been completed by accumulating a predetermined amount of charge in the AF target focus detection area. If the integration has been completed (S508: YES), the subroutine ends. If the predetermined amount of charge accumulation has not been reached and integration has not been completed (S508: NO), light emission is stopped according to the light emission interval determined in step S504 (S509). Next, the light emission process from step S503 is repeated.
[0037]
Table 3 shows the light emission times according to the number of times of light emission when the respective parameters are as follows.
Reference light emission time = 10 μs
Correction time = 2μs
Reference light emission interval = 10 ms
Correction interval = 2ms
Number of corrections = 2
Maximum number of flashes = 10
As shown in Table 3, the light emission time is increased according to the number of times of light emission.
[0038]
[Table 3]

[0039]
Returning to the flowchart of FIG. 3, when the integration is completed in step S108, a distance measurement calculation for calculating the defocus amount based on the integration result is executed in step S109. When the effective defocus amount is obtained and the distance measurement is OK (S110: NO), the flash auxiliary light distance measurement OK flag is set to “1”. If the effective defocus amount cannot be obtained and the distance measurement is NG (S110: YES), the flash auxiliary light distance measurement NG flag is set to “1”, and the process proceeds to step S113 in FIG.
[0040]
In step S113, the AF mode is not a spot AF mode that uses only the center spot (focus detection area C), but a wide range of focus detection areas such as the wide AF mode and the center three-point AF mode are selected as the AF target area. It is determined whether or not the area AF mode is set. If the area AF mode is set (S113: YES), the process proceeds to step S116. If the contrast value is greater than or equal to the specified value in the integration and distance measurement calculation (S108, S109) using the flash auxiliary light (S114: YES), the process proceeds to step S116. That is, the projection LED 85 is not used in the area AF mode. In step S116, the flash auxiliary light flag is set to “1”, and the distance measurement calculation result by the flash auxiliary light is validated. Next, in step S117, when the distance measurement result by the flash auxiliary light is OK (S117: NO), the process proceeds to step S152. That is, if the contrast is in the area AF mode or when the subject is detected with flash auxiliary light and the contrast calculation is OK, the measurement of the flash auxiliary light is performed in the processing after step S152. Lens driving according to the distance result is started.
[0041]
If it is not the area AF mode and the contrast detected with the flash auxiliary light does not reach the specified value or more, it is determined in step S115 whether or not the use of the projection LED is permitted. As shown in FIG. 1, when a light projection LED 85 is mounted in the flash device 80, the light projection LED can be used, and thus the light projection LED is permitted. If the floodlight LED is not permitted (S115: NO), the process proceeds to step S116.
[0042]
If the projection LED is permitted (S115: YES), integration is performed by projecting a projection pattern from the projection LED 85 onto the subject in step S119, and ranging calculation is performed in step S120. Next, a measurement calculation result is determined in step S121.
[0043]
If the distance measurement is OK, the process proceeds to step S126. If it is determined in step S126 that the flash auxiliary light ranging is NG (S126: YES), the projection LED flag is set to “1”, and the process proceeds to the processes in and after step S152. Since the projection LED flag is set, the distance measurement result by the projection LED is validated, and the re-emission process for confirming the in-focus state after being focused once in the processing after step S152. A projection LED is used as the AF auxiliary light. If it is determined in step S126 that the flash auxiliary light ranging is OK (S126: NO), the process proceeds to step S127.
[0044]
The process proceeds to step S127 when both the flash auxiliary light and the distance measurement of the projection LED are OK. In this case, the reliability of the distance measurement calculation results obtained through the phase difference distance measurement calculation process including correlation calculation and interpolation calculation is compared. For example, the higher the degree of correlation in the correlation calculation, the higher the reliability of the distance measurement result. In addition, for example, the steeper slope of the calculation value calculated in the correlation calculation has a higher contrast, so that the reliability of the distance measurement result is determined based on this slope. If the reliability of the distance measurement calculation using the flash auxiliary light is higher (S127: YES), the flash auxiliary light flag is set to “1” in step S128, and the result of the distance measurement calculation using the flash auxiliary light is validated. . When the reliability of the distance calculation by the light emitting LED is higher (S127: NO), the light emitting LED flag is set to “1” in step S129, and the result of the distance calculation by the light emitting LED is validated. . Thereafter, the process proceeds to the processes in and after step S152, and lens driving is started based on the distance measurement result by the auxiliary light that is considered to be effective. In addition, the auxiliary light that is effective in step S128 or S129 is used as AF auxiliary light in the re-emission process for confirming the in-focus state after being focused once.
[0045]
On the other hand, when the distance measurement calculation by the projection LED is NG in step S121 (S121: YES), the distance measurement result by the flash auxiliary light is determined in step S122. If it is determined in step S122 that the distance measurement result using the flash auxiliary light is OK (S122: NO), the process proceeds to step S128, and the flash auxiliary light flag is set to “1”. If it is determined in step S122 that the distance measurement result using the flash auxiliary light is NG (S122: YES), the process proceeds to step S123.
[0046]
The process proceeds to step S123 when both the distance measurement calculation result by the flash light and the distance calculation result by the projection LED are NG. In this case, in step S123, the contrast in both distance measurement is compared. When the contrast of the flash auxiliary light is larger (S123: YES), the flash auxiliary light flag is set to “1”. When the contrast by the floodlight LED is larger (S123: NO), the floodlight LED flag is set to “1”. Next, in step S118, after a flag used during the search driving process is set, the search driving process after step S137 is started.
[0047]
Except for the case where the flash light is enabled when the area AF mode (S113: YES) or the contrast by the flash light is greater than or equal to a predetermined value (S114: YES), which auxiliary is performed by the process of FIG. 4 described above. Whether or not the distance measurement result by light is valid is determined as shown in Table 4 below. As shown in Table 4, when both distance measurement is OK, it is determined by reliability, when one is distance measurement OK, OK is more effective, and when both distance measurement is NG, it is determined by contrast.
[0048]
[Table 4]

[0049]
If the flash auxiliary light is not permitted in step S106 of FIG. 3 (S106: NO), the flash auxiliary light cannot be used, and the process proceeds to step S130 to determine whether or not the projection LED is permitted. The When the projection LED is permitted (S130: YES), the projection LED flag is set to “1” in order to validate the distance measurement result by the projection LED (S131). Next, integration is performed while irradiating the projection LED, and ranging calculation is performed in step S133. If the result of the distance measurement calculation is OK (S134: NO), the process proceeds to step S152 to drive the lens according to the distance measurement result. On the other hand, if the distance measurement is NG (S134: YES), a flag used for search drive processing is set in step S135. Thereafter, the process proceeds to a search driving process after step S137. In addition, even when the projection LED is not permitted in step S130 (S130: NO), after the flag is set in step S136, the process proceeds to the search drive processing in step S137 and subsequent steps.
[0050]
The meanings of the flags used in the processes shown in FIG. 3 and subsequent figures are summarized below.
“Flash auxiliary light”: When this flag is “1”, this indicates that the distance measurement result by the flash auxiliary light should be treated as valid.
“Projection LED”: When this flag is “1”, it indicates that the distance measurement result by the projection LED should be treated as valid.
“Search”: Indicates that search drive is executed when this flag is “1”.
“ToFar”: indicates that the lens should be driven to the far side when this flag is “1”.
“ToNear”: When this flag is “1”, this indicates that the lens should be driven to the short distance side.
“INVDRV”: used to instruct whether or not the driving direction is further reversed when the focus adjustment lens 52 reaches the end point. When this flag is “1”, it indicates that no inversion drive is performed.
[0051]
If the distance measurement result is OK in step S103 (FIG. 3), the distance measurement result is OK in step S134 (FIG. 3), or if the flash auxiliary light distance measurement is OK in step S117 (FIG. 4), step S128. If the flash auxiliary light flag is set in step S129, or if the projection LED flag is set in step S129, the effective defocus amount is obtained by either or both of the auxiliary lights. In these cases, the process proceeds to step S152 (FIG. 6) in order to drive the lens according to the obtained defocus amount.
[0052]
In step S152 of FIG. 6, the distance measurement result is confirmed. If the distance measurement is NG, the process returns to step S148. In the case of moving from step S103, S134, S117, S128, or S129 here, the distance measurement result is basically OK. If the distance measurement is OK in step S152, it is determined whether or not the defocus amount as a result of the distance measurement calculation is within the focus range. Note that the defocus amount used here is a defocus amount as a result of distance measurement using effective auxiliary light or a result of distance measurement without using auxiliary light. If it is not within the focus range (S153: NO), the position of the focus is confirmed in steps S154 and S155.
[0053]
When the focal point of the subject image is on the far side from the film surface equivalent position (S154: YES), the ToFar flag is set (S158), and the process proceeds to the AF motor driving process in step S160. In step S160, the focus adjustment lens 52 is driven according to the drive amount obtained by multiplying the effective defocus amount by the K value (in this case, toward the far side). When the focal point of the subject image is on the short distance side instead of the long distance side (S155: YES), the ToNear flag is set (S159), and the process proceeds to the AF motor driving process in step S160. In step S160, the focus adjustment lens 52 is driven according to the drive amount obtained by multiplying the effective defocus amount by the K value (in this case, toward the short distance side).
[0054]
Details of the AF motor drive subroutine called in step S160 are shown in FIG. As shown in FIG. 8, in step S201, the number of drive pulses is set based on the effective defocus amount. Next, the lens driving direction is confirmed, and when driving to the far side (S202: YES), driving toward the far side is started. On the other hand, if it is determined in step S203 that the driving is toward the short distance side, driving toward the short distance side is started in step S205. After the process of step S204 or S205, this subroutine ends. If the lens driving direction is not obtained (S203: NO), the process proceeds to step S148. The CPU 20 starts a process of down-counting the lens driving pulse set in step S201 according to the number of pulses actually driven by the lens. After the process of step S204 or S205, the subroutine ends, the process proceeds to step S161 of FIG. 7, and an overlap process is executed. (Interrupt processing)
[0055]
If it is determined in step S153 in FIG. 6 that the in-focus state is obtained, the process proceeds to step S156, and flash zoom return processing is executed. Next, when the setting of the camera body 10 is AF lock that maintains the state once focused (S157: YES), the process loops as it is. If not (S157: NO), the process returns to step S151.
[0056]
Details of the flash zoom return processing subroutine in step S156 are shown in FIG. In the flash zoom recovery process, first, in step S414, information on the focal length is acquired from the photographing lens 50 side. Next, in step S415, the acquired focal length is stored in the variable “Z”. Next, flash zoom data is set according to 'Z' (S412), and the set flash zoom data is transmitted to the flash device 80 side (S413). Then, after the predetermined wait process (S414), the subroutine ends. Therefore, the position of the light emitting unit 82 in the flash device 80 is moved to the zoom position corresponding to the focal length of the photographing lens 50 instead of the zoom position according to the AF mode by the flash zoom recovery process. That is, preparation for flash photography is completed.
[0057]
FIG. 7 shows an overlap process in which integration and distance measurement calculations are performed while driving the lens, and the number of lens drive pulses is updated based on the latest distance measurement result. As shown in FIG. 7, in step S161, integration and ranging calculation are performed without using auxiliary light. In step S162, the distance measurement calculation result in step S161 is confirmed. When the effective defocus amount cannot be obtained and the distance measurement is NG (S162: YES), the process of step S161 is repeated. If the distance measurement is OK (S162: NO), then the in-focus position of the subject image is determined.
[0058]
When it is determined that the focal point of the subject image is on the far side (S163: YES), the value of the ToFar flag is confirmed. When the ToFar flag is “1” and the lens is facing in the long distance direction which is the in-focus direction (S167: YES), the lens driving pulse is updated based on the latest distance measurement result in step S161. (S165), and the overlap processing from step S161 is repeated. Even when the focus position of the subject image is on the near side in step S164 (S164: YES) and the lens driving direction is also on the near side (S166: YES), the lens driving pulse is the latest in step S161. It is updated based on the distance measurement result (S165), and the overlap processing from S161 is repeated.
[0059]
In step S167, it is determined that the lens driving direction is opposite to the in-focus direction (S167: NO) when the focus adjustment lens 52 has gone too far. Similarly, when the ToNear flag is not “1” in step S166 (S166: NO), the focus adjustment lens 52 has gone too far. In these cases, the process returns to step S148 to stop lens driving.
[0060]
In FIG. 6, the stack is cleared in step S148. Next, in step S149, the AF motor 23 is stopped. Further, in step S150, each flag is cleared. Next, in step S151, after integration and distance measurement calculation using normal outside light is performed without using auxiliary light, the process proceeds to step S152 to start lens driving based on the distance measurement result.
[0061]
Next, the search drive operation will be described with reference to FIG. The process from step S137 executed after step S135, S136, or S118 is a search drive process. In the search driving process, the distance measurement calculation is repeatedly executed until the distance measurement calculation is OK while moving the focus adjustment lens 52 until it reaches the end point according to the set flag.
[0062]
In step S137, the number of drive pulses that allows the focus adjustment lens 52 to reliably reach the end on the short distance side or the long distance side from the current position is set. In step S138, lens driving is started according to the set number of driving pulses. In step S139, normal integration and distance measurement are performed using external light. As a result, an effective defocus amount is obtained, and when it is determined that the focal point is on the far side (S140: YES), the lens driving direction is confirmed in step S145. When the lens driving direction is on the far side as in the in-focus direction (S145: YES), the driving pulse is updated with the number of pulses based on the distance measurement result obtained in step S139 (S146). Next, in step S147, the search flag is cleared, and the process proceeds to step S161 to perform overlap processing. In step S145, when the lens driving direction is not the long distance side (S145: NO), it is a case where the focus adjustment lens 52 has gone too far, and the process proceeds to step S148 to stop the lens driving.
[0063]
If it is determined that the in-focus point is on the short distance side (S141: YES), the lens driving direction is confirmed in step S144. When the lens driving direction is the short distance direction as well as the in-focus direction (S144: YES), the driving pulse is updated with the number of pulses based on the distance measurement result obtained in step S139 (S146). Next, in step S147, the search flag is cleared, and the process proceeds to step S161 to perform overlap processing. In step S144, when the lens driving direction is not the short distance side (S144: NO), it is a case where the focus adjustment lens 52 has gone too far, and the process proceeds to step S148 to stop the lens driving.
[0064]
If an effective defocus amount is obtained in step S142 and it is determined that the in-focus state is obtained (S142: YES), the process proceeds to step S148 to stop lens driving.
[0065]
If it is determined in step S142 that the subject is not in focus (S142: NO), the result of the distance measurement calculation in step S139 is confirmed (S143). If the calculation is NG (S143: YES), the process returns to step S139 to continue the search drive. If the calculation is OK in step S143, the process proceeds to step S148.
[0066]
FIG. 9 is a flowchart of an interrupt process called when driving for the number of pulses for driving the focus adjustment lens 52 is completed (when the downcount value reaches 0). In other words, when the lens driving to the in-focus position is completed, the interrupt routine of FIG. 9 is started.
[0067]
In FIG. 9, first, the AF motor 23 is stopped (S301). Next, focus detection is performed again for confirmation in a state where driving of the focus adjustment lens 52 is completed by the processing of steps S302 to S309. At this time, when the auxiliary light is used first, the auxiliary light used first is emitted. That is, if the flash auxiliary light flag is “1” in step S302, if the distance measurement result using the flash light is determined to be valid in the first distance measurement, it is also used as auxiliary light here. Integration is performed using flash light (S308). Thereafter, the process proceeds to step S305, and after each flag is cleared and the stack is cleared (S305, S306), a distance measurement calculation is performed (S307).
[0068]
In the first distance measurement, when the distance measurement result by the light projection LED is valid (S303: YES), the light projection LED is also emitted here and integration is executed (S309). Thereafter, the process proceeds to step S305. When the auxiliary light is not used (S303: NO), the integration is executed without using the auxiliary light (S304), and then the process proceeds to step S305. After the distance measurement calculation is performed in step S307, the process proceeds to the processes in and after step S152. However, since it is driven to the focal point, it is basically determined that the in-focus state is obtained in step S153. . As described above, the processing of FIG. 9 improves the AF accuracy because the focus detection is performed again after the lens driving is stopped and the lens is driven when necessary. At this time, the projection LED flag or the flash auxiliary light flag is set, and the effective auxiliary light is used, so that focus detection is surely performed.
[0069]
FIG. 10 is a flowchart showing an interrupt process executed when the focus adjustment lens 52 reaches the end point on the long distance side or the short distance side. That is, the end point detection interrupt routine of FIG. 10 is started when the focus adjustment lens 52 reaches the end point of the movement range when the focus adjustment lens 52 is driven by search drive processing or the like.
[0070]
In the end point detection interrupt processing routine of FIG. 10, first, in step S351, it is confirmed whether or not the number of driving pulses of the AF motor 23 exceeds a predetermined value within a predetermined limit time. If the number of pulses is equal to or greater than the predetermined value (S351: YES), the interrupt process ends. If the number of pulses does not reach the predetermined value (S351: NO), the process proceeds to step S352 and subsequent steps. In step S352, the AF motor 23 is stopped. Next, the stack is cleared and the limit flag is set (S353, S354). Next, it is determined whether or not the search flag is “1”. If the search flag is not set (S355: NO), the process proceeds to step S148 (FIG. 6).
[0071]
On the other hand, if the search flag is set (S355: YES), whether or not to reverse the lens driving direction is determined according to the value of the INVDRV flag.
[0072]
In step S356, ranging calculation is performed with the focus adjustment lens 52 at the end point. If the calculation is OK (S357: NO), after each flag is cleared (S364), the process proceeds to step S152 to drive the lens. If the distance measurement is NG (S357: YES), the value of the INVDRV flag is confirmed in step S358. As shown in step S135 and step S118, in the distance measurement using the auxiliary light, the distance measuring point is more easily obtained on the far distance side, and therefore the driving (inversion) is not intentionally performed on the near distance side. The process proceeds to S365.
[0073]
In step S365, by checking the flash auxiliary light flag, if the auxiliary light used first is flash light (S365: YES), the flash auxiliary light is emitted and integration is executed (S368). Next, a pulse calculation is performed to stop the focus adjustment lens 52 at a subject distance position of 3 meters (S370), a ToNear flag is set (S371), and the process proceeds to step S138. When the auxiliary light used first is a light projecting LED (S366: YES), the light projecting LED is emitted to perform integration. Thereafter, the process proceeds to step S370. On the other hand, when the auxiliary light is not used (S366: NO), each flag is cleared (S367), and the process proceeds to step S148.
[0074]
On the other hand, if INVDRV is not “1” in step S358 (S358: NO), processing for reversing the lens driving direction and continuing search driving is performed. When the search driving process is entered from step S136 (FIG. 3) and the end point is first detected, INVDRV = 0. In this case, inversion driving is performed.
[0075]
In step S359, when it is determined that the end point is on the short distance side (N limit) (S359: YES), the ToFar flag and the INVDRV flag are set (S361, S363), and the process proceeds to step S137. That is, the search drive is continued toward the far end point side. When the end point is detected next time, the INVDRV flag is set so that the driving direction is not reversed and search driving is not performed. On the other hand, when the end point is on the far side (F limit) (S360: YES), the ToNear flag and the INVDRV flag are set (S362, S363), and the process proceeds to step S137. That is, the search drive is continued toward the short distance end side. If it is not the F limit in step S360, the process returns to step S101.
[0076]
All the elements in the flowchart as the embodiment of the present invention described above are not necessary for realizing the autofocus device of the present invention, and can be variously modified. For example, the order in which the flash auxiliary light and the light emitting LED emit light can be switched. In the flash zoom change process in step S107 (FIG. 3), it is not always necessary that the light emitting unit is zoom-driven, and a fixed irradiation angle may be used. Further, there may be an embodiment in which the re-light emission process described in FIG. 9 is omitted.
[0077]
【The invention's effect】
As described above, according to the present invention, the optimum auxiliary light is used according to various conditions such as the contrast of the subject, the AF mode, and the distance measurement result, that is, the features of each auxiliary light are accurately extracted. AF accuracy when using auxiliary light is improved.
[Brief description of the drawings]
FIG. 1 is a block diagram of a control system of a camera system to which a flash auxiliary light system of the present invention is applied.
FIG. 2 is a diagram showing an arrangement of focus detection areas in a photographing screen of the camera system of FIG.
FIG. 3 is a flowchart showing AF processing together with FIGS.
FIG. 4 is a flowchart showing AF processing together with FIG. 3 and FIGS.
5 is a flowchart showing AF processing together with FIGS. 3, 4, 6, and 7. FIG.
FIG. 6 is a flowchart showing AF processing together with FIGS. 3 to 5 and FIG. 7;
FIG. 7 is a flowchart showing AF processing together with FIGS.
FIG. 8 is a flowchart of an AF motor drive processing subroutine.
FIG. 9 is a flowchart of interrupt processing executed when a drive pulse is counted down to 0.
FIG. 10 is a flowchart of an end point detection interrupt process executed when the focus adjustment lens reaches an end point.
FIG. 11 is a flowchart of a flash zoom change processing subroutine.
FIG. 12 is a flowchart of a flash auxiliary light & integration processing subroutine.
[Explanation of symbols]
2 Main mirror
3 Submirror
4 Penta prism
5 Metering IC
6 CCD sensor unit
10 Camera body
12 Peripheral control circuit
20 CPU
23 AF motor
50 Photography lens
52 Focusing lens
54 Lens control unit
80 flash device
81 Flash control circuit
82 Light Emitting Unit
85 Flood LED

Claims (6)

Auto that has a flash device that emits flash light and a light emitting LED that emits a light projection pattern as auxiliary light during AF (autofocus) operation, and controls lens driving based on the focus detection result of either auxiliary light A focus device,
First, the flash light is emitted to perform focus detection. If the contrast of the subject image by the flash light is equal to or greater than a predetermined value, lens drive control is performed based on the focus detection result by the flash light, and the contrast is equal to or greater than the predetermined value. If not, the projection LED is then caused to emit light, focus detection is performed, and the more reliable focus detection result of each auxiliary light is selected, and the lens based on the selected focus detection result is selected. An autofocus device comprising control means for performing drive control. As an auxiliary light at the time of AF (autofocus) operation, an autofocus device having a flash device that emits flash light and a light projection LED that projects a light projection pattern,
Focus detection means for performing focus detection based on a subject image;
When auxiliary light is required, light emission control means for causing the flash device and the light projecting LED to emit light sequentially in any order, and causing the focus detection means to perform focus detection by emitting auxiliary light, and
Based on the focus detection result obtained by the control operation of the light emission control means, the following rules (1), (2), and (3) are:
(1) When the contrast of the subject image by the flash light is a predetermined value or more, the focus detection result by the flash light is validated. (2) The focus detection NG (effective defocus amount cannot be obtained) The focus detection result is validated. (3) When both the focus detection results by the auxiliary light are focus detection OK (an effective defocus amount is obtained), the more reliable focus detection result is obtained. A decision unit that preferentially applies the rule (1) to be validated and decides which auxiliary light is used to validate the focus detection result;
Lens drive control means for driving and controlling the focus adjustment lens based on the focus detection result validated by the determination means;
An autofocus device comprising: The light emission control unit first emits the flash light and causes the focus detection unit to perform focus detection,
The determination means performs determination based only on the rule (1) when a focus detection result by the flash light is obtained,
3. The autofocus device according to claim 2, wherein when the contrast by the flash light is equal to or greater than a predetermined value, the projection LED does not emit light.   When the focus adjustment lens is driven to the in-focus position, the auxiliary light which is considered to be effective is emitted again to perform focus detection, and the lens driving control is performed based on the focus detection result again. 4. The autofocus device according to claim 2, further comprising re-emission control means for driving the lens by the means. When both of the focus detection results by the auxiliary light are focus detection NG, the focus detection means detects the focus while driving the focus adjustment lens until it reaches the far end of the moving range by the lens drive control means. Further provided is a search drive control means for stopping the lens drive when the focus is achieved.
In order to determine the auxiliary light used when the re-light emitting means emits light again, the determining means includes the following rule (4),
(4) The autofocus device according to claim 4, wherein when both are focus detection NG, the one having the larger contrast of the subject image is applied.   When the AF mode is not the spot AF mode in which the spot at the center of the shooting screen is an AF target but the area AF mode in which an area wider than the spot AF mode is an AF target, the light emission control unit is configured to use the flash light. 6. The autofocus device according to claim 2, wherein only the light is emitted, and the determination unit validates the focus detection result by the flash light regardless of the respective rules. 7.

Images