JP3696989B2 - Focus detection device and camera using the same - Google Patents

Description

但し、ｘ，ｙ，ｚは３軸座標であり、数１式は２次曲線を表す式であり、ｋ＝０で球面を、ｋ＝−１で放物面を、ｋ＞−１で回転楕円面となる。また、ｈ²＝ｙ²＋ｚ²であり、ｒは軸上の曲率を表す。通常のカメラと対物レンズ（撮影レンズ）を想定した場合、ｒとｋの範囲は、
−２０≦ ｒ ≦２０ −１＜ ｋ ≦−０.２
程度が好ましい。
【００３２】
また本実施形態においては、２次結像系９の第一面を凹面形状とすることで、２次結像系９に入射する光が無理に屈折されることがないような構成とし、光電変換素子１１の二次元領域の広い範囲にわたって良好で一様な結像性能を確保している。このようにして得られた２つの光量分布に対して、図１３において説明したのと同様な原理に基づき、分離方向即ち図３に示す２つのエリアセンサ１１−１，１１−２の上下方向の相対的位置関係をエリアセンサ１１−１，１１−２の各位置で算出することで、対物レンズの焦点状態を二次元的に検出することができる。尚、第１の反射鏡４は、撮影に際し、主ミラー３と同様に撮影光路外に退避されるものである。
【００３３】
図４は本実施形態における焦点検出領域の分布の様子をカメラのファインダから見た状態で描いたものである。図のように、本実施形態では撮影画面３１の中央部分に上下３分割及び２分割の検出領域を交互に配置し、全体で計２７分割領域（図中、□が１領域を表す）を千鳥状態に設定したものとなっている。
【００３４】
これにより、図１７ほどではないが二次元的な領域を扱うには必要かつ十分な領域数が確保されている。
【００３５】
又、撮影画面３１の中心には、基本的に検出領域が設定されるべきと考える。
そこで本実施形態では、図４の焦点検出領域の分布を拡大した図５に示した様に撮影画面中心（図中、■で表示）を含む上下、左右方向には奇数（３及び５）の分割領域を設定し、更に見た目にも安定して使い易くなるよう、中心に対して上下、左右に、線対称となるよう領域設定を行っている。
【００３６】
また本実施形態では、撮影画面の長辺方向に検出領域を数多く配置するために左右方向に密、上下方向に粗となる分割状態を行っている。図５で説明すると、左右、上下各方向の測距領域の配置間隔ｈ，ｖについて、ｈ＜ｖなる関係を設定している。これは撮影画面３１の上下、左右の辺の長さと、配置間隔が逆の関係であり、分割数では同じ関係となる。これにより、測距点を二次元的により密に分布させることが可能となった。
【００３７】
尚、本実施形態では、ｈ＜ｖであるが、ｖ＜２ｈでもある。２ｈとは上下方向に同じ分割状態（即ち、３分割あるいは２分割）となる左右の間隔である。
【００３８】
ｖ＞２ｈ あるいは ２ｖ＜ｈ
とすると、間のあいた配置という印象が大きくなってしまう。
【００３９】
以上の様な２７個の分割領域の各々に対応するように、光電変換素子１１の２つのエリアセンサ１１−１，１１−２をそれぞれ２７分割して用いる。
【００４０】
図６は、エリアセンサ対の１つのエリアセンサについて分割の様子を示した図である。図からわかるように、限られた画素数のセンサを縦方向に３分割及び２分割で用いることで、個々の領域に対し十分な画素数を割り当てて検出能力を高めるとともに、一度で分割形態の異なる全領域の蓄積が終了し、検出動作の応答性も良いものとなる。
【００４１】
又、図６での撮影画面の上下のライン方向（３分割及び２分割方向）が位相差の発生する方向であり、エリアセンサを構成している光電変換素子の１画素の短辺方向となっている。この光電変換素子の配置は、エリアセンサに効率よく測距点を密に配置するために大変有効である。
【００４２】
図７は本実施形態のエリアセンサ用蓄積制御回路部の概要である。図２０とは異なり、各分割領域（対）毎にセンサ領域５２ー１，５２ー２，……５２ーｎと、最大値検出回路部５３ー１，５３ー２，……５３ーｎと、差動アンプ（ＡＰ１〜ＡＰｎ）５５ー１，５５ー２，……５５ーｎと、各センサ領域毎にダーク領域５４ー１，５４ー２，……５４ーｎを持ち、各差動アンプ（ＡＰ１〜ＡＰｎ）の出力が共通の所定レベル（ＶＲ）に到達するまで蓄積を行い、到達時点で蓄積動作終了、読みだし信号（φＲ）が、各分割領域のセンサ領域５２ー１，５２ー２，……５２ーｎ毎に送られるものである。ここで、各分割領域毎の独立蓄積制御を可能にしながら回路規模の縮小を計るため、制御回路部５１が基準クロック信号ＩＣＬＫに基づいて、各分割領域毎に設けられたアナログスイッチ対ＡＳ１ａ，ＡＳ１ｂ〜ＡＳｎａ，ＡＳｎｂを順次走査し、共通のコンパレータＣＯＭ５６で、全センサ領域の蓄積終了判断を行っている。上記の各センサ領域はエリアセンサ対に対応してセンサ領域対として最大値を検出していて、各センサ領域について各光電変換素子の最大値を検出して光電荷の蓄積を終了し、その後不図示の各センサ領域の各光電変換素子の電荷量を読み出すことで、焦点検出のための所定の配置となるように撮影レンズの位置を調節する。
【００４３】
なお、上述したように、図３での光電変換素子１１の２つのエリアセンサ部１１−１，１１−２は同時に、そして各分割領域対においては、共通信号（各分割領域対毎の最大出力値）に基づいて蓄積制御が行われている。
【００４４】
又、本実施形態では焦点検出領域を２７分割しているので、上記ｎは２７となる。この２７分割は左右に５分割を加えて３７分割と、又は左右に５分割を引いて１７分割としてもよいし、上下に２分割の列と３分割の列に分割した上記実施形態に対して、上下に３分割の列と４分割の列とを対としてもよく、上記実施形態に限られない。
【００４５】
［第２の実施形態］
図８は上記のごとき各実施形態に示した各焦点検出装置を備えたカメラの具体的な構成の一例を示す回路図であり、先ず各部の構成について説明する。
【００４６】
図８において、ＰＲＳはカメラの制御装置で、例えば、内部にＣＰＵ（中央処理装置）、ＲＯＭ、ＲＡＭ、Ａ／Ｄ、Ｄ／Ａ変換機能を有する１チップのマイクロコンピュータである。マイクロコンピュータＰＲＳはＲＯＭに格納されたカメラのシーケンス・プログラムに従って、自動露出制御機能、自動焦点調節機能、フィルムの巻き上げ・巻き戻し等のカメラの一連の動作を行っている。そのために、マイクロコンピュータＰＲＳは通信用信号ＳＯ、ＳＩ、ＳＣＬＫ、通信選択信号ＣＬＣＭ、ＣＤＤＲ、ＣＩＣＣを用いて、カメラ本体内の周辺回路およびレンズ内制御装置と通信を行って、各々の回路やレンズの動作を制御する。
【００４７】
ＳＯはマイクロコンピュータＰＲＳから出力されるデータ信号、ＳＩはマイクロコンピュータＰＲＳに入力されるデータ信号、ＳＣＬＫは信号ＳＯ、ＳＩの同期クロックである。
【００４８】
ＬＣＭはレンズ通信バッファ回路であり、カメラが動作中のときにはレンズ用電源端子ＶＬに電力を供給するとともに、マイクロコンピュータＰＲＳからの選択信号ＣＬＣＭが高電位レベル（以下、‘Ｈ’と略記し、低電位レベルは‘Ｌ’と略記する）のときには、カメラとレンズ間の通信バッファとなる。
【００４９】
マイクロコンピュータＰＲＳが選択信号ＣＬＣＭを‘Ｈ’にして、同期クロックＳＣＬＫに同期して所定のデータをデータ信号ＳＯから送出すると、レンズ通信バッファ回路ＬＣＭはカメラ・レンズ間通信接点を介して、同期クロックＳＣＬＫ、データ信号ＳＯの各々のバッファ信号ＬＣＫ、ＤＣＬをレンズへ出力する。それと同時に、レンズＬＮＳからの信号ＤＬＣのバッファ信号をデータ信号ＳＩに出力し、マイクロコンピュータＰＲＳは同期クロックＳＣＬＫに同期してデータ信号ＳＩからレンズのデータを入力する。
【００５０】
ＤＤＲは各種のスイッチＳＷＳの検知および表示用回路であり、信号ＣＤＤＲが‘Ｈ’のとき選択され、データ信号ＳＯ、ＳＩ、同期クロックＳＣＬＫを用いてマイクロコンピュータＰＲＳから制御される。即ち、マイクロコンピュータＰＲＳから送られてくるデータに基づいてカメラの表示部材ＤＳＰの表示を切り替えたり、カメラの各種操作部材のオン・オフ状態を通信によってマイクロコンピュータＰＲＳに報知する。ＯＬＣはカメラ上部に位置する外部液晶表示装置であり、ＩＬＣはファインダ内部液晶表示装置である。本実施形態では、焦点検出の動作領域の設定等は、この検知および表示用回路ＤＤＲに属するスイッチＳＷＳにて行っている。
【００５１】
ＳＷ１、ＳＷ２は不図示のレリーズボタンに連動したスイッチで、レリーズボタンの第一段階の押下によりＳＷ１がオンし、引き続いて第２段階の押下でＳＷ２がオンする。マイクロコンピュータＰＲＳはＳＷ１オンで測光、自動焦点調節を行い、ＳＷ２オンをトリガとして露出制御とその後のフィルムの巻き上げを行う。
【００５２】
なお、ＳＷ２はマイクロコンピュータであるＰＲＳの「割り込み入力端子」に接続され、ＳＷ１オン時のプログラム実行中でもＳＷ２オンによって割り込みがかかり、直ちに所定の割り込みプログラムへ制御を移すことができる。
【００５３】
ＭＴＲ１はフィルム給送用、ＭＴＲ２はミラーアップ・ダウンおよびシャッタばねチャージ用のモータであり、各々の駆動回路ＭＤＲ１、ＭＤＲ２により正転、逆転の制御が行われる。マイクロコンピュータＰＲＳから駆動回路ＭＤＲ１、ＭＤＲ２に入力されている信号Ｍ１Ｆ、Ｍ１Ｒ、Ｍ２Ｆ、Ｍ２Ｒはモータ制御用の正転及び反転制御信号である。
【００５４】
ＭＧ１、ＭＧ２は各々シャッタ先幕・後幕走行開始用マグネットで、制御信号ＳＭＧ１、ＳＭＧ２、増幅トランジスタＴＲ１、ＴＲ２により通電され、マイクロコンピュータＰＲＳによりシャッタ制御が行われる。
【００５５】
なお、モーター駆動回路ＭＤＲ１、ＭＤＲ２、シャッタ制御は、本発明と直接関わりがないので、詳しい説明は省略する。
【００５６】
レンズＬＮＳ内制御回路ＬＰＲＳにバッファ信号ＬＣＫと同期して入力されるバッファ信号ＤＣＬは、カメラからレンズＬＮＳに対する命令のデータであり、命令に対するレンズＬＮＳの動作は予め決められている。レンズＬＮＳ内制御回路ＬＰＲＳは、所定の手続きに従ってその命令を解析し、焦点調節や絞り制御の動作や、出力ＤＬＣからレンズＬＮＳの各部動作状況（焦点調節光学系の駆動状況や、絞りの駆動状態等）や、各種パラメータ（開放Ｆナンバ、焦点距離、デフォーカス量対焦点調節光学系の移動量の係数、各種ピント補正量等）の出力を行う。
【００５７】
本実施形態では、ズームレンズの例を示しており、カメラから焦点調節の命令が送られた場合には、同時に送られてくる駆動量・方向に従って焦点調節用モータＬＭＴＲを信号ＬＭＦ、ＬＭＲによって駆動して、光学系を光軸方向に正逆移動させて焦点調節を行う。光学系の移動量は光学系に連動して回動するパルス板のパターンをフォトカプラーにて検出し、移動量に応じた数のパルスを出力するエンコーダ回路ＥＮＣＦのパルス信号ＳＥＮＣＦでモニタし、レンズＬＮＳ内制御回路ＬＰＲＳ内のカウンタで計数しており、焦点調節用レンズの所定の移動が完了した時点でレンズＬＮＳ内制御回路ＬＰＲＳ自身が信号ＬＭＦ、ＬＭＲを‘Ｌ’にしてモータＬＭＴＲを制動する。
【００５８】
このため、一旦カメラから焦点調節の命令が送られた後は、カメラの制御装置であるマイクロコンピュータＰＲＳはレンズの駆動が終了するまで、レンズ駆動に関して全く関与する必要がない。また、カメラから要求があった場合には、上記カウンタの内容をカメラに送出することも可能な構成になっている。
【００５９】
カメラから絞り制御の命令が送られた場合には、同時に送られてくる絞り段数に従って、絞り駆動用としては公知のステッピング・モータＤＭＴＲを駆動する。なお、ステッピング・モータＤＭＴＲはオープン制御が可能なため、動作をモニタするためのエンコーダを必要としない。
【００６０】
ＥＮＣＺはズーム光学系に付随したエンコーダ回路であり、レンズＬＮＳ内制御回路ＬＰＲＳはエンコーダ回路ＥＮＣＺからの信号ＳＥＮＣＺを入力してズーム位置を検出する。レンズＬＮＳ内制御回路ＬＰＲＳ内には各ズーム位置におけるレンズ・パラメータが格納されており、カメラ側のマイクロコンピュータＰＲＳから要求があった場合には、現在のズーム位置に対応したパラメータをカメラ側に送出する。
【００６１】
ＩＣＣは、光電変換素子であるＣＣＤ等から構成される焦点検出用エリアセンサ及びその駆動制御回路である焦点検出回路であり、選択信号ＣＩＣＣが‘Ｈ’のとき選択されて、データ信号ＳＯ、ＳＩ、同期信号ＳＣＬＫを用いてマイクロコンピュータＰＲＳから制御される。
【００６２】
ΦＶ、ΦＨ、ΦＲはエリアセンサ出力の読み出し、リセット信号であり、マイクロコンピュータＰＲＳから信号に基づいて焦点検出回路ＩＣＣ内の駆動回路によりセンサ制御信号が生成される。センサ出力はセンサ部からの読み出し後増幅され、出力信号ＩＭＡＧＥとしてマイクロコンピュータＰＲＳのアナログ入力端子に入力され、マイクロコンピュータＰＲＳは出力信号ＩＭＡＧＥをＡ／Ｄ変換後、そのデジタル値をＲＡＭ上の所定のアドレスへ順次格納してゆく。これらデジタル変換された信号を用いて焦点検出を行っていく。
【００６３】
ＶＲは前述した各差動アンプに共通の蓄積終了判定レベルであり、ＩＮＴＥは蓄積終了出力信号、ＩＣＬＫは焦点検出回路ＩＣＣ内の制御回路部の基準クロック信号である。
【００６４】
上述のカメラの全システム中、特に焦点検出回路ＩＣＣの動作は第１乃至第６の実施形態で説明したようにエリアセンサによる焦点検出の動作を行ない、その結果はマイクロコンピュータＰＲＳを介してレンズＬＮＳ内制御回路ＬＰＲＳにより適切な焦点ポイントにレンズ系を移動・保持し、その後シャッターが動作することで、焦点のあった画像を取得することができる。
【００６５】
尚、上記図８ではカメラとレンズＬＮＳが別体（レンズ交換が可能）となるもので表現されているが、本発明はカメラ・レンズ一体なるものでも何等問題なく、これ等に限定されるものではない。
【００６６】
［第３実施形態］
以上の実施形態においては、焦点検出のエリアセンサによる測距点の配置間隔をあえて上下、左右方向で非同等としている。しかし、例えばカメラにおいては縦位置撮影のように上下、左右の定義が反転する使い方もある。この場合でも違和感無く使用できるようにするには上下、左右の配置間隔を同等にすればよい。
【００６７】
この場合の測距点配置を図９に示した。ここでの先述したｈ，ｖの関係は
ｈ＝ｖ
である。
【００６８】
一方、使用するエリアセンサ等の制約から、上下、左右方向には同数の測距点を配置する場合も考えられる。この場合は、測距点の配置間隔を撮影画面の辺の長さの関係と同等にすると使い易いものとなる。図１０はその一例で、上下、左右の両方向において、撮影画面の辺の長さに対し同じ比率の測距領域の広がりを有する装置となる。図１１におけるｈとｖの関係が撮影画面の左右と上下の辺の長さの関係と同じになるわけで、今度は逆に撮影画面の設定をｈとｖの関係が良好になるようにすると良い。
【００６９】
【発明の効果】
以上説明してきた本発明によれば、撮影画面又は観察画面上の広い範囲に渡り二次元的、連続的に焦点検出をする焦点検出装置において、個々の焦点検出領域の能力が最大限に引き出され、必要十分な数の検出領域が無駄無く配置され、全領域の蓄積制御が一度で可能となる。
【００７０】
また、本発明の焦点検出装置によれば、エリアセンサを焦点検出に用いる場合、エリアセンサを、最大効率で合理的に使用することができる。さらに、この焦点検出装置を撮影装置のカメラに用いることで、構成的に小型で簡易に且つ正確な高密度の焦点位置を得ることができる。従って、検出能力、操作性、更に応答性も良い検出装置の提供が可能となる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態の焦点検出装置の概略構成図である。
【図２】本発明の第１の実施形態の絞りおよび２次結像系を示す図である。
【図３】本発明の第１の実施形態の光電変換素子を示す図である。
【図４】本発明の実施形態の焦点検出領域の分布を示す図である。
【図５】本発明の実施形態の焦点検出領域の分布を説明する図である。
【図６】本発明の実施形態の光電変換素子の領域分割を説明する図である。
【図７】本発明の実施形態のエリアセンサ用蓄積制御回路部の概要を示す図である。
【図８】本発明の実施形態であるカメラおよびレンズの回路図である。
【図９】本発明の第２の実施形態の焦点検出領域の分布を説明する図である。
【図１０】本発明の第３の実施形態の焦点検出領域の分布を示す図である。
【図１１】本発明の第３の実施形態の焦点検出領域の分布を説明する図である。
【図１２】従来の焦点検出装置のカメラ内配置図である。
【図１３】従来の焦点検出装置を説明する図である。
【図１４】従来の焦点検出領域の分布を示す図である。
【図１５】焦点検出領域を二次元に拡大した場合を示す図である。
【図１６】焦点検出領域を二次元に拡大した場合の光電変換素子を示す図である。
【図１７】焦点検出領域が二次元の場合の理想的な測距点配置図である。
【図１８】二次元に測距点配置を行った場合の問題点の説明図である。
【図１９】二次元に測距点配置を行った場合のエリアセンサの平面図である。
【図２０】従来の二次元に測距点配置を行った場合の焦点検出装置のブロック図である。
【図２１】二次元に測距点配置を行った場合の焦点検出領域と画面の信号図である。
【図２２】二次元に測距点配置を行った場合の各領域の画素の電荷蓄積の出力図である。
【符号の説明】
１ 対物レンズの光軸
２ フィルム
３ 主ミラー
４ 第１の反射鏡
５ 結像面
６ 第２の反射鏡
７ 赤外カットフィルタ
８ 絞り
９ ２次結像系
１０ 第３の反射鏡
１１ 光電変換素子
１２ 光束
２４ 対物レンズの光軸
３１ 撮影画面領域
１０１ 対物レンズ
１０２ 主ミラー
１０３ 焦点板
１０４ ペンタプリズム
１０５ 接眼レンズ
１０６ サブミラー
１０７ フィルム
１０８ 焦点検出装置
１０９ 視野マスク
１１０ フィールドレンズ
１１１ ２次結像系
１１２ 光電変換素子
１１３ 絞り
１１４ 対物レンズの射出瞳
１１５ 光束
Ａ 撮影画面領域
Ｂ 焦点検出領域
ＰＲＳ カメラ内制御装置
ＬＣＭ レンズ通信バッファ回路
ＳＤＲ センサ駆動回路
ＬＮＳ レンズ
ＬＰＲＳ レンズ内制御回路
ＥＮＣＦ 焦点調節用レンズの移動量検出エンコーダ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera, a photographing device such as a video, or a focus detection device of various observation devices. More specifically, the present invention relates to a focus detection apparatus that can continuously detect a focus two-dimensionally over a wide range on a photographing screen or an observation screen.
[0002]
[Prior art]
FIG. 12 shows an example of a camera incorporating a conventional focus detection device.
In the figure, 101 is an objective lens that calls in and captures an object image, 102 is a semi-transmissive main mirror that reflects image light from the objective lens 101, and 103 is a focusing screen disposed at the focal position of the objective lens 101. Denotes a pentaprism that changes the direction of the light beam, 105 denotes an eyepiece for the photographer, 106 denotes a sub-mirror that operates during focus detection, 107 denotes a film such as a silver salt film, and 108 denotes a focus detection device.
[0003]
In this figure, light from a subject not shown is transmitted through the objective lens 101 and then reflected upward by the main mirror 102 to form an image on the focusing screen 103. The image formed on the focusing screen 103 is visually recognized by the photographer or the observer through the eyepiece 105 through a plurality of reflections by the pentaprism 104. Further, the light beam transmitted through the main mirror 102 can expose the film 107 to obtain an image of the object.
[0004]
On the other hand, a part of the light beam reaching the main mirror 102 from the objective lens 101 is transmitted through the main mirror 102, reflected downward by the sub mirror 106, and guided to the focus detection device 108.
[0005]
FIG. 13 is an exploded view showing only the objective lens 101 and the focus detection device 108 in FIG. 12 in order to explain the principle of focus detection.
[0006]
In the focus detection apparatus 108 of FIG. 13, 109 is a field mask arranged near the target focal plane of the objective lens 101, that is, near the plane conjugate with the film plane, 110 is a field lens arranged similarly near the target focal plane, 111 Is a secondary imaging system composed of two lenses 111-1 and 111-2, and 112 is a pair of sensor arrays 112-1 and 112 arranged behind the two lenses 111-1 and 111-2. -2 includes a photoelectric conversion element 113, a diaphragm having two openings 113-1 and 113-2 arranged corresponding to the two lenses 111-1 and 111-2, and 114 a divided two regions The exit pupils of the objective lens 101 including 114-1 and 114-2 are shown. The field lens 110 has an effect of forming an image in the vicinity of the openings 113-1 and 113-2 of the stop 113 corresponding to the regions 114-1 and 114-2 of the exit pupil 114 of the objective lens 101. The light beams 115-1 and 115-2 transmitted through the regions 114-1 and 114-2 of the exit pupil 114 form light quantity distributions in the two sensor rows 112-1 and 112-2, respectively. Yes.
[0007]
The focus detection apparatus 108 shown in FIG. 13 is generally called a phase difference detection method. When the imaging point of the objective lens 101 is on the front side of the planned focal plane, that is, on the objective lens 101 side. Is a state in which the light quantity distributions relating to the object images formed on the two sensor arrays 112-1 and 112-2 are close to each other, and the imaging point of the objective lens 101 is on the rear side of the planned focal plane, The light quantity distributions formed on the two sensor rows 112-1 and 112-2 are in a state of being separated from each other. In addition, the amount of deviation of the light amount distribution formed on each of the two sensor rows 112-1 and 112-2 has a certain functional relationship with the defocus amount of the objective lens 101, that is, the focal point deviation amount. When calculated by the means, the direction and amount of defocus of the objective lens 101 can be detected. The distance is measured according to the direction and the amount, and the position of the lens system is moved according to the direction and the amount so that the shift amount becomes almost zero, and the focus detection operation is finished.
[0008]
[Problems to be solved by the invention]
In the camera incorporating the conventional focus detection apparatus 108 shown in FIG. 12, the focus detection area is narrow and one-dimensional as shown in the area B with respect to the shooting screen A as shown in FIG. This is determined by the detection apparatus using a set of line sensor arrays 112-1 and 112-2 shown in FIG. Here, if the optical factors such as the imaging magnification on the line sensor array are considered to be the same, the focus detectable range (field length and depth) becomes wider and deeper as the number of pixels increases.
[0009]
On the other hand, if the focus detection range is not one-dimensional but a two-dimensional surface having a certain spread, a detection device that is easier to use can be provided.
[0010]
Therefore, when aiming at further expansion of the detection region, a focus detection device using a photoelectric conversion element having a light receiving portion that is two-dimensionally spread, that is, an area sensor, is required.
[0011]
FIG. 15 shows a detection region (B) in a focus detection apparatus using an area sensor, and the detection region is greatly enlarged as compared with FIG. The photoelectric conversion elements used here are area sensor pairs 112-1 and 112-2 in which two area regions are arranged as shown in FIG. 16 if the phase difference detection method is performed. The light receiving area of the area sensor pair is divided into a plurality of parts, and a phase difference is detected in each of them, thereby making it possible to detect a focus having a two-dimensional spread.
[0012]
However, the problem here is the relationship between the detection capability and the number of pixels described above.
That is, if the number of divided areas, that is, the number of detection areas is increased in order to fully utilize the extended distance measurement area, the number of pixels in each area decreases, resulting in a device with insufficient detection capability. However, if the number of pixels in the divided area is ensured to be sufficiently large, the space between the detection areas is widened, resulting in an unusable device having scattered detection areas.
[0013]
This will be described in detail. The detection area (B) in FIG. 15, that is, the area sensors 112-1 and 112-2 in FIG. If nine regions) can be set, there is almost no problem in terms of the number of detection regions. However, when this area division (5 areas in the vertical direction, FIG. 18A) is simply performed, the number of pixels in each area decreases. Although it is sufficiently possible to increase the number of pixels by miniaturizing the sensor, this presents another problem of realizing highly efficient photoelectric conversion with a narrower opening.
[0014]
On the other hand, in the area setting as shown in FIG. 18B (three vertical divisions) and (C) (two vertical divisions) in which the number of divisions is reduced, the distance measurement capability of each divided area is sufficient. The number of detection areas is not satisfactory. Therefore, it is conceivable to use these two types of division together, but in order to optimize the image signal in each region, it is necessary to perform accumulation twice in each division state.
[0015]
This will be described below. Normally, accumulation control for the area sensor pairs 112-1 and 112-2 as shown in FIG. 19 is performed as a collective control of the entire area by the common dark pixel 125, maximum value detection circuit 122 and accumulation control unit 124 as shown in FIG. Become.
The output value VP of the pixel that outputs the maximum value from each pixel output of the area sensor pair 121 and the output VD of the dark pixel 125 common to the area sensor pairs 112-1 and 112-2 (both are 121). The difference is input to the differential amplifier 123, and is input to the accumulation control unit 124. The difference is compared with the reference level VR. When the output of the differential amplifier 123 exceeds the reference level VR, the read signal ΦR is output. This readout signal φR is input to the area sensor pair 121 to instruct the end of accumulation of each photoelectric conversion element of the area sensor pair 121 and to start reading of each photoelectric conversion element.
[0016]
According to FIG. 20, the output of the dark pixel 125 that is shielded in common to the two area sensor units 112-1 and 112-2 and the maximum detection that is common to the two area sensor pairs 112-1 and 112-2. Accumulation is performed until the difference between the output of the circuit 122, that is, the output of the pixel indicating the maximum value, reaches a predetermined level VR. Is sent to the column 121.
[0017]
In order to simplify the explanation, it is assumed that an image signal Y as shown in FIG. 21 is formed on the area sensor, and the area sensor area is divided into four areas G to J as shown in the figure.
[0018]
FIG. 22 shows the state of the image signal corresponding to each of the four areas in FIG. As can be seen from the figure, because of the control over the entire area, the accumulation state is appropriate for the divided area H having the maximum output pixel in the area, but is insufficient for the other divided areas. As a result. In this case, even if the detection area is expanded in two dimensions, the detectable area does not widen, and the meaning of using the area sensor is lost.
[0019]
That is, in order to maximize the capability of each detection area, it is necessary to secure a sufficient number of pixels for each divided area and to perform accumulation control in units of divided areas.
[0020]
However, for this reason, the use in which the accumulation is performed in two steps as described above is not satisfactory in terms of responsiveness.
[0021]
[Means for Solving the Problems]
The object of the present invention is to solve the above-mentioned problems, and the gist thereof is as follows. That is, in a focus detection device that enables continuous two-dimensional focus detection over a wide range on a photographing screen or an observation screen, a plurality of photoelectric conversion means having a continuous two-dimensional spread as a light receiving unit are provided. The focus detection areas set by dividing into a plurality of areas are staggered with respect to each other in the imaging screen area.
Further, the present invention detects a defocus amount of the photographing lens from a plurality of photoelectric conversion means having a continuous two-dimensional spread for receiving a light beam from a subject passing through the photographing lens, and an output of the photoelectric conversion means. In the focus detection apparatus, each focus detection area in which the photoelectric conversion means is divided and set into a plurality of areas is arranged in the imaging screen area so that the positions thereof are shifted from each other in the phase difference detection direction. The length of the field of view overlaps the adjacent field of focus detection in the phase difference detection direction.
[0022]
Further, in the division of the plurality of photoelectric conversion means, the upper and lower and left and right areas including the center of the photographing screen are divided into odd numbers, and the divided areas are set symmetrically in the upper and lower and right and left including the center. Further, the arrangement intervals of the plurality of focus detection areas are unequal in the vertical and horizontal directions. The arrangement interval is characterized in that the horizontal direction is narrower than the vertical direction in a normal use state. The direction in which the arrangement interval is wide is a direction in which a phase difference is generated in focus detection by the phase difference detection method.
[0023]
Furthermore, the focus detection apparatus is used in a camera, and an area sensor is divided to obtain an accurate focus detection signal by an optimal focus detection region and its arrangement.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an optical layout diagram of each component for performing focus detection in each region in the photographing screen.
[0025]
[First Embodiment]
FIG. 1 is an optical layout diagram of each component for performing focus detection in each region in the photographing screen. In the figure, 1 is the optical axis of an objective lens (not shown) arranged on the left side of the figure, 2 is a silver salt film arranged at the focal position of the objective lens, and 3 is arranged on the optical axis 1 of the objective lens. The semi-transparent main mirror 4 is similarly a first reflecting mirror disposed obliquely on the optical axis 1 of the objective lens, and 5 is a paraxial image conjugate to the film 2 by the first reflecting mirror 4. Surface 6 is a second reflecting mirror for focus detection, 7 is an infrared cut filter for blocking infrared rays, 8 is a diaphragm having two openings 8-1 and 8-2, and 9 is two openings 8 of the diaphragm 8. -1 and 8-2, a secondary imaging system having two lenses 9-1 and 9-2, 10 is a third reflecting mirror for focus detection, and 11 is two area sensors 11 -1 and 11-2 are respectively shown.
[0026]
Here, the first reflecting mirror 4 has a curvature, and has a convergent power for projecting the two openings 8-1 and 8-2 of the diaphragm 8 in the vicinity of the exit pupil of an objective lens (not shown). Further, the first reflecting mirror 4 is deposited with a metal film such as aluminum or silver so that only a necessary region reflects light, and also serves as a field mask for limiting the range in which focus detection is performed. In the other reflecting mirrors 6 and 10 as well, only the minimum necessary area is deposited in order to reduce the stray light incident on the photoelectric conversion element 11. It is also effective to apply a light-absorbing paint or the like to a region that does not function as a reflecting surface of each of the reflecting mirrors 4, 6, 10 or to provide a light shielding member in the vicinity.
[0027]
FIG. 2 is a plan view of the diaphragm 8 in which two horizontally long openings 8-1 and 8-2 are arranged in a direction in which the opening width is narrow. The dotted lines in the figure indicate the lenses 9-1 and 9-2 of the secondary imaging system 9 disposed behind the apertures 8-1 and 8-2 corresponding to the apertures 8-1 and 8-2. It is.
[0028]
FIG. 3 is a schematic plan view of the photoelectric conversion element 11. The two area sensors 11-1 and 11-2 shown in FIG. 1 are two-dimensionally arranged area sensors as shown in FIG. Two are arranged side by side.
[0029]
In the above configuration, the light beams 12-1 and 12-2 from one objective lens (not shown) of FIG. 1 are transmitted through the main mirror 3, and then are substantially tilted by the first reflecting mirror 4. , And the direction is again changed by the second reflecting mirror 6, and then passes through the two apertures 8-1 and 8-2 of the infrared cut filter 7 and the diaphragm 8, and the secondary imaging system 9. Are respectively collected by the lenses 9-1 and 9-2 and reach the area sensors 11-1 and 11-2 of the photoelectric conversion element 11 via the third reflecting mirror 10, respectively. The light beams 12-1 and 12-2 in the figure indicate the light beam that forms an image at the center of the film 2, but the light beam that forms an image at other positions also passes through the same path to the photoelectric conversion element 11. As a whole, two light quantity distributions corresponding to a predetermined two-dimensional area on the film 2 are formed on the area sensors 11-1 and 11-2 of the photoelectric conversion element 11.
[0030]
In this embodiment, the 1st reflective mirror 4 is comprised by a part of curved surface formed by rotating a quadratic curve around an axis | shaft, and a spheroidal surface is used especially suitably. In FIG. 1, the surface shape of the first reflecting mirror 4 is composed of a part of a spheroid formed by rotating an ellipse 21 having a point 20 as an apex around the axis 22 of the ellipse 21, and the focal point thereof is the second. Are set in the vicinity of the image position 23 at the center of the diaphragm 8 by the reflecting mirror 6 and a point (not shown) on the extension of the optical axis 24 after passing through the main mirror 3. If the point on the extension of the optical axis 24 of the objective lens is near the exit pupil position of the objective lens (or the average exit pupil position when various objective lenses are used interchangeably), the objective lens Thus, the first reflecting mirror 4 functions as an ideal field lens. As is apparent from FIG. 1, the first reflector 4 is optically used in a region that does not include the rotation axis and vertex of the spheroid. The specific shape of the spheroid of this embodiment is relative to the coordinate axis of FIG.
[0031]
[Expression 1]

However, x, y, and z are triaxial coordinates, and Formula 1 is a formula that represents a quadratic curve. When k = 0, the spherical surface is rotated, k = −1, the paraboloid is rotated, and k> −1. It becomes an ellipsoid. H ² = y ² + z ² , and r represents the on-axis curvature. Assuming a normal camera and objective lens (photographing lens), the range of r and k is
−20 ≦ r ≦ 20−1 <k ≦ −0.2
The degree is preferred.
[0032]
In the present embodiment, the first surface of the secondary imaging system 9 is formed in a concave shape so that light incident on the secondary imaging system 9 is not refracted by force. Good and uniform imaging performance is ensured over a wide range of the two-dimensional region of the conversion element 11. The two light quantity distributions thus obtained are separated in the vertical direction of the two area sensors 11-1 and 11-2 shown in FIG. 3 based on the same principle as described in FIG. By calculating the relative positional relationship at each position of the area sensors 11-1 and 11-2, the focus state of the objective lens can be detected two-dimensionally. The first reflecting mirror 4 is retracted out of the photographing optical path in the same manner as the main mirror 3 when photographing.
[0033]
FIG. 4 shows the focus detection area distribution in this embodiment as viewed from the viewfinder of the camera. As shown in the figure, in the present embodiment, detection areas of upper and lower three divisions and two divisions are alternately arranged in the central portion of the photographing screen 31, and a total of 27 divided areas (in the figure, □ represents one area) are staggered as a whole. It is set to the state.
[0034]
As a result, the number of areas necessary and sufficient for handling a two-dimensional area is secured, although not as much as in FIG.
[0035]
Further, it is considered that a detection area should basically be set at the center of the shooting screen 31.
Therefore, in the present embodiment, as shown in FIG. 5 in which the distribution of the focus detection area in FIG. 4 is enlarged, odd numbers (3 and 5) are included in the vertical and horizontal directions including the center of the shooting screen (indicated by ■ in the figure). Divided areas are set, and the areas are set so as to be line symmetric vertically and horizontally with respect to the center so as to be stable and easy to use.
[0036]
In the present embodiment, in order to arrange a large number of detection areas in the long side direction of the shooting screen, a division state is performed that is dense in the left-right direction and coarse in the up-down direction. Referring to FIG. 5, a relationship of h <v is set for the distances h and v between the distance measurement areas in the left and right and up and down directions. This is an inverse relationship between the lengths of the upper and lower and left and right sides of the shooting screen 31 and the arrangement interval, and the same relationship is obtained in the number of divisions. As a result, the distance measurement points can be more densely distributed two-dimensionally.
[0037]
In this embodiment, h <v, but v <2h. 2h is a left and right interval that is the same in the vertical direction (ie, divided into three or divided into two).
[0038]
v> 2h or 2v <h
If so, the impression of an arrangement in between will increase.
[0039]
The two area sensors 11-1 and 11-2 of the photoelectric conversion element 11 are used by being divided into 27 parts so as to correspond to each of the 27 divided areas as described above.
[0040]
FIG. 6 is a diagram showing a state of division for one area sensor of the area sensor pair. As can be seen from the figure, by using a sensor with a limited number of pixels in the vertical direction in three and two divisions, a sufficient number of pixels can be assigned to each region to increase detection capability, and at the same time, Accumulation of all the different areas is completed, and the response of the detection operation is good.
[0041]
In addition, the upper and lower line directions (three-divided and two-divided directions) of the photographing screen in FIG. 6 are directions in which a phase difference is generated, which is the short-side direction of one pixel of the photoelectric conversion element constituting the area sensor. ing. This arrangement of the photoelectric conversion elements is very effective for efficiently arranging the distance measuring points in the area sensor.
[0042]
FIG. 7 is an outline of the area sensor accumulation control circuit unit of the present embodiment. Unlike FIG. 20, the sensor areas 52-1, 52-2,... 52-n and the maximum value detection circuit sections 53-1, 53-2,. Differential amplifiers (AP1 to APn) 55-1, 55-2,... 55-n and dark regions 54-1, 54-2,. Accumulation is performed until the outputs of the amplifiers (AP1 to APn) reach a common predetermined level (VR). When the output reaches the common predetermined level (VR), the accumulation operation ends. -2, ... Sent every 52-n. Here, in order to reduce the circuit scale while enabling independent accumulation control for each divided area, the control circuit unit 51 uses the analog clock pair AS1a, AS1b provided for each divided area based on the reference clock signal ICLK. ˜ASna and ASnb are sequentially scanned, and the common comparator COM56 determines whether or not to accumulate all the sensor areas. Each of the above sensor areas detects the maximum value as a sensor area pair corresponding to the area sensor pair, detects the maximum value of each photoelectric conversion element for each sensor area, ends photocharge accumulation, and then By reading the charge amount of each photoelectric conversion element in each illustrated sensor region, the position of the photographic lens is adjusted so that a predetermined arrangement for focus detection is obtained.
[0043]
As described above, the two area sensor units 11-1 and 11-2 of the photoelectric conversion element 11 in FIG. 3 are simultaneously and in each divided region pair, a common signal (maximum output for each divided region pair). The accumulation control is performed based on the value.
[0044]
In this embodiment, since the focus detection area is divided into 27, n is 27. The 27 divisions may be 37 divisions by adding 5 divisions on the left and right, or 17 divisions by subtracting 5 divisions on the left and right, or the above embodiment divided into 2 division columns and 3 division columns up and down. The upper and lower columns may be divided into three and four columns, and the present invention is not limited to the above embodiment.
[0045]
[Second Embodiment]
FIG. 8 is a circuit diagram showing an example of a specific configuration of a camera provided with each focus detection device shown in each embodiment as described above. First, the configuration of each section will be described.
[0046]
In FIG. 8, PRS is a camera control device, for example, a one-chip microcomputer having a CPU (Central Processing Unit), ROM, RAM, A / D, and D / A conversion function therein. The microcomputer PRS performs a series of camera operations such as an automatic exposure control function, an automatic focus adjustment function, and film winding / rewinding according to the camera sequence program stored in the ROM. For this purpose, the microcomputer PRS uses the communication signals SO, SI, SCLK, the communication selection signals CLCM, CDDR, and CICC to communicate with the peripheral circuit in the camera body and the in-lens control device, and each circuit and lens. To control the operation.
[0047]
SO is a data signal output from the microcomputer PRS, SI is a data signal input to the microcomputer PRS, and SCLK is a synchronous clock of the signals SO and SI.
[0048]
The LCM is a lens communication buffer circuit that supplies power to the lens power supply terminal VL when the camera is in operation, and a selection signal CLCM from the microcomputer PRS is a high potential level (hereinafter abbreviated as 'H', low When the potential level is abbreviated as “L”), it becomes a communication buffer between the camera and the lens.
[0049]
When the microcomputer PRS sets the selection signal CLCM to “H” and sends predetermined data from the data signal SO in synchronization with the synchronization clock SCLK, the lens communication buffer circuit LCM receives the synchronization clock via the camera-lens communication contact. Buffer signals LCK and DCL of SCLK and data signal SO are output to the lens. At the same time, the buffer signal of the signal DLC from the lens LNS is output to the data signal SI, and the microcomputer PRS inputs lens data from the data signal SI in synchronization with the synchronization clock SCLK.
[0050]
DDR is a circuit for detecting and displaying various switches SWS, and is selected when the signal CDDDR is “H”, and is controlled from the microcomputer PRS using the data signals SO and SI and the synchronous clock SCLK. That is, the display of the display member DSP of the camera is switched based on the data sent from the microcomputer PRS, and the on / off state of various operation members of the camera is notified to the microcomputer PRS by communication. OLC is an external liquid crystal display device located above the camera, and ILC is a finder internal liquid crystal display device. In the present embodiment, setting of an operation region for focus detection and the like is performed by the switch SWS belonging to the detection and display circuit DDR.
[0051]
SW1 and SW2 are interlocked with a release button (not shown), and SW1 is turned on when the release button is pressed at the first stage, and SW2 is turned on when the release button is pressed at the second stage. The microcomputer PRS performs photometry and automatic focus adjustment when SW1 is ON, and performs exposure control and subsequent film winding with SW2 ON as a trigger.
[0052]
Note that SW2 is connected to the “interrupt input terminal” of the PRS which is a microcomputer, and even when the program is executed when SW1 is turned on, an interrupt is generated when SW2 is turned on, and control can be immediately transferred to a predetermined interrupt program.
[0053]
MTR1 is a film feeding motor, MTR2 is a mirror up / down motor and a shutter spring charging motor, and forward drive and reverse drive are controlled by respective drive circuits MDR1 and MDR2. Signals M1F, M1R, M2F, and M2R input from the microcomputer PRS to the drive circuits MDR1 and MDR2 are forward and reverse control signals for motor control.
[0054]
MG1 and MG2 are shutter front curtain and rear curtain travel start magnets, respectively, which are energized by control signals SMG1 and SMG2 and amplification transistors TR1 and TR2, and shutter control is performed by the microcomputer PRS.
[0055]
The motor drive circuits MDR1 and MDR2 and the shutter control are not directly related to the present invention, and detailed description thereof is omitted.
[0056]
The buffer signal DCL input to the intra-lens LNS control circuit LPRS in synchronization with the buffer signal LCK is command data for the lens LNS from the camera, and the operation of the lens LNS for the command is determined in advance. The control circuit LPRS in the lens LNS analyzes the command according to a predetermined procedure, and operates the focus adjustment and the aperture control, the operation status of each part of the lens LNS from the output DLC (the drive status of the focus adjustment optical system, the drive status of the aperture) Etc.) and various parameters (open F number, focal length, defocus amount vs. moving amount coefficient of the focus adjusting optical system, various focus correction amounts, etc.).
[0057]
This embodiment shows an example of a zoom lens. When a focus adjustment command is sent from the camera, the focus adjustment motor LMTR is driven by signals LMF and LMR in accordance with the drive amount and direction sent simultaneously. Then, the focal point is adjusted by moving the optical system forward and backward in the optical axis direction. The amount of movement of the optical system is monitored by a pulse signal SENCF of an encoder circuit ENCF that outputs a number of pulses corresponding to the amount of movement by detecting the pattern of a pulse plate that rotates in conjunction with the optical system with a photocoupler. It is counted by a counter in the LNS control circuit LPRS, and when the predetermined movement of the focus adjustment lens is completed, the lens LNS control circuit LPRS itself sets the signals LMF and LMR to 'L' to brake the motor LMTR. .
[0058]
For this reason, once the focus adjustment command is sent from the camera, the microcomputer PRS, which is the camera control device, does not need to be involved in lens driving at all until the lens driving is completed. Further, when requested by the camera, the contents of the counter can be sent to the camera.
[0059]
When an aperture control command is sent from the camera, a known stepping motor DMTR for driving the aperture is driven according to the number of aperture stages sent simultaneously. Since the stepping motor DMTR can be controlled open, an encoder for monitoring the operation is not required.
[0060]
ENCZ is an encoder circuit associated with the zoom optical system, and the lens LNS control circuit LPRS receives the signal SENCZ from the encoder circuit ENCZ and detects the zoom position. The lens parameter at each zoom position is stored in the lens LNS control circuit LPRS, and when there is a request from the microcomputer PRS on the camera side, a parameter corresponding to the current zoom position is sent to the camera side. To do.
[0061]
ICC is a focus detection area sensor composed of a CCD or the like which is a photoelectric conversion element and a focus detection circuit which is a drive control circuit thereof, and is selected when the selection signal CICC is 'H' and the data signals SO and SI Control is performed from the microcomputer PRS using the synchronization signal SCLK.
[0062]
ΦV, ΦH, and ΦR are area sensor output readout and reset signals, and a sensor control signal is generated by a drive circuit in the focus detection circuit ICC based on the signal from the microcomputer PRS. The sensor output is amplified after being read out from the sensor unit, and input to the analog input terminal of the microcomputer PRS as the output signal IMAGE. The microcomputer PRS converts the output signal IMAGE from analog to digital, and then converts the digital value to a predetermined value on the RAM. Store sequentially to the address. Focus detection is performed using these digitally converted signals.
[0063]
VR is an accumulation end determination level common to the above-described differential amplifiers, INTE is an accumulation end output signal, and ICLK is a reference clock signal of a control circuit unit in the focus detection circuit ICC.
[0064]
In the entire system of the cameras described above, the focus detection circuit ICC particularly performs the focus detection operation by the area sensor as described in the first to sixth embodiments, and the result is the lens LNS via the microcomputer PRS. By moving and holding the lens system to an appropriate focal point by the inner control circuit LPRS and then operating the shutter, a focused image can be acquired.
[0065]
In FIG. 8, the camera and the lens LNS are expressed as separate bodies (lens exchange is possible), but the present invention is not limited to this, even if the camera and the lens are integrated. is not.
[0066]
[Third Embodiment]
In the embodiment described above, the arrangement intervals of the distance measuring points by the focus detection area sensor are not equal in the vertical and horizontal directions. However, for example, in a camera, there is a usage in which the definitions of up and down and left and right are reversed as in vertical position shooting. Even in this case, the vertical and horizontal arrangement intervals may be made equal in order to enable use without a sense of incongruity.
[0067]
The distance measuring point arrangement in this case is shown in FIG. The relationship between h and v described above is h = v
It is.
[0068]
On the other hand, there may be a case where the same number of distance measuring points are arranged in the vertical and horizontal directions due to restrictions on the area sensor used. In this case, it becomes easy to use the distance measuring point arrangement interval equal to the relationship between the lengths of the sides of the shooting screen. FIG. 10 shows an example thereof, which is a device having a range-finding area spread in the same ratio with respect to the length of the side of the photographing screen in both the vertical and horizontal directions. The relationship between h and v in FIG. 11 is the same as the relationship between the lengths of the left and right and upper and lower sides of the shooting screen. Conversely, if the setting of the shooting screen is made to have a good relationship between h and v. good.
[0069]
【The invention's effect】
According to the present invention described above, in the focus detection apparatus that performs focus detection two-dimensionally and continuously over a wide range on the imaging screen or observation screen, the capability of each focus detection region is maximized. A necessary and sufficient number of detection areas are arranged without waste, and accumulation control of all areas can be performed at once.
[0070]
Further, according to the focus detection apparatus of the present invention, when the area sensor is used for focus detection, the area sensor can be reasonably used with maximum efficiency. Furthermore, by using this focus detection device for the camera of the photographing apparatus, it is possible to obtain a high-density focus position that is small in size, simple and accurate. Therefore, it is possible to provide a detection device with good detection capability, operability, and responsiveness.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a focus detection apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a stop and a secondary imaging system according to the first embodiment of the present invention.
FIG. 3 is a diagram showing a photoelectric conversion element according to the first embodiment of the present invention.
FIG. 4 is a diagram showing a distribution of focus detection areas according to the embodiment of the present invention.
FIG. 5 is a diagram illustrating the distribution of focus detection areas according to the embodiment of the present invention.
FIG. 6 is a diagram illustrating area division of the photoelectric conversion element according to the embodiment of the present invention.
FIG. 7 is a diagram showing an overview of an area sensor accumulation control circuit unit according to an embodiment of the present invention;
FIG. 8 is a circuit diagram of a camera and a lens according to an embodiment of the present invention.
FIG. 9 is a diagram illustrating the distribution of focus detection areas according to the second embodiment of the present invention.
FIG. 10 is a diagram showing a distribution of focus detection areas according to a third embodiment of the present invention.
FIG. 11 is a diagram illustrating the distribution of focus detection areas according to the third embodiment of the present invention.
FIG. 12 is a layout diagram of a conventional focus detection device in a camera.
FIG. 13 is a diagram illustrating a conventional focus detection apparatus.
FIG. 14 is a diagram showing a distribution of a conventional focus detection area.
FIG. 15 is a diagram illustrating a case where a focus detection area is enlarged two-dimensionally.
FIG. 16 is a diagram illustrating a photoelectric conversion element when a focus detection region is enlarged two-dimensionally.
FIG. 17 is an ideal distance measurement point arrangement diagram when the focus detection area is two-dimensional.
FIG. 18 is an explanatory diagram of problems that occur when distance measurement points are arranged two-dimensionally.
FIG. 19 is a plan view of an area sensor when distance measuring points are arranged two-dimensionally.
FIG. 20 is a block diagram of a focus detection device when conventional ranging point arrangement is performed in two dimensions.
FIG. 21 is a signal diagram of a focus detection area and a screen when ranging point arrangement is performed in two dimensions.
FIG. 22 is an output diagram of charge accumulation of pixels in each region when ranging point arrangement is performed two-dimensionally.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical axis 2 of objective lens Film 3 Main mirror 4 First reflective mirror 5 Imaging surface 6 Second reflective mirror 7 Infrared cut filter 8 Aperture 9 Secondary imaging system 10 Third reflective mirror 11 Photoelectric conversion element 12 Light flux 24 Optical axis 31 of objective lens Imaging screen area 101 Objective lens 102 Main mirror 103 Focus plate 104 Pentaprism 105 Eyepiece lens 106 Submirror 107 Film 108 Focus detection device 109 Field mask 110 Field lens 111 Secondary imaging system 112 Photoelectric conversion Element 113 Diaphragm 114 Exit pupil 115 of objective lens Light flux A Shooting screen area B Focus detection area PRS In-camera control device LCM Lens communication buffer circuit SDR Sensor drive circuit LNS Lens LPRS In-lens control circuit ENCF Movement amount detection encoder for focus adjustment lens

Claims (12)

In a plurality of photoelectric conversion means having a continuous two-dimensional spread to receive a light beam from a subject that has passed through the photographing lens, and a focus detection device that detects the defocus amount of the photographing lens from the output of the photoelectric conversion means,
Each focus detection area, which is set by dividing the photoelectric conversion means into a plurality of areas, is arranged in the imaging screen area so as to be shifted from each other in the phase difference detection direction, and the length of the field of view for one focus detection is A focus detection apparatus that overlaps with a visual field of adjacent focus detection in a phase difference detection direction .   2. The focus detection apparatus according to claim 1, wherein the number of divisions of the plurality of focus detection areas is an odd number in the upper, lower, left and right areas including the center of the shooting screen (optical axis of the shooting lens).   2. The focus detection apparatus according to claim 1, wherein the setting positions of the plurality of focus detection areas are line symmetric vertically and horizontally including the center of the shooting screen (optical axis of the shooting lens).   The focus detection apparatus according to claim 1, wherein the arrangement intervals of the plurality of focus detection areas are unequal in the vertical and horizontal directions.   The focus detection apparatus according to claim 4, wherein the arrangement interval is narrower in a horizontal direction than in a vertical direction in a normal use state.   The focus detection apparatus according to claim 4, wherein the direction in which the arrangement interval is wide is a direction in which a phase difference is generated in focus detection by a phase difference detection method.   The focus detection apparatus according to claim 4, wherein the relationship between the lengths of the arrangement intervals is opposite to the relationship between the lengths of the sides of the photographing screen.   The focus detection apparatus according to claim 4, wherein a relationship between the lengths of the arrangement intervals is such that the upper, lower, left and right do not exceed twice the other.   The focus detection apparatus according to claim 1, wherein the relationship between the number of divisions of each of the plurality of focus detection areas in the direction is the same as the relationship between the lengths of the sides of the shooting screen.   The focus detection apparatus according to claim 1, wherein the arrangement intervals of the plurality of focus detection areas are equal in the vertical and horizontal directions.   The focus detection apparatus according to claim 4, wherein the relationship between the lengths of the arrangement intervals is the same as the relationship between the lengths of the sides of the photographing screen.   A camera using the focus detection device according to claim 1.

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