JP2004151628A - Range-finding device and camera device equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a range-finding device for a camera having simple structure and appropriately measuring a distance to a subject in a short period of time. <P>SOLUTION: The range-finding device 21 is equipped with a range-finding part 4 having a plurality of sensor elements P<SB>1</SB>, P<SB>2</SB>to P<SB>200</SB>taking in light from the subject, and a control circuit 30 controlling the range-finding part 4. The range-finding part 4 performs preliminary light take-in by the sensor elements P<SB>1</SB>, P<SB>2</SB>to P<SB>200</SB>, and the control circuit 30 decides whether or not light quantity in a range-finding area on a center side is relatively lower than that in a range-finding area on the outside concerning the light quantity distribution of the range-finding areas A<SB>a</SB>, A<SB>b</SB>, A<SB>c</SB>, A<SB>d</SB>and A<SB>e</SB>, and controls the range-finding part 4 to perform the light take-in for measuring the subject distance until the specified number of sensor elements out of the sensor elements belonging to the range-finding area on the center side are saturated when the light quantity on the center side is relatively lower than that on the outside. <P>COPYRIGHT: (C)2004,JPO

Description

【００２６】
（１）式において、第２項は各センサ素子の輝度値の総和を示すのに対して、第１項は中央側の測距エリアにあるセンサ素子の輝度値よりも外側の測距エリアにあるセンサ素子の輝度値に重み付けが行われており、中央側の測距エリアにあるセンサ素子の輝度値よりも外側の測距エリアにあるセンサ素子の輝度値の方が大きいほど大きい値を示すようになっている。
【００２７】
つぎに、測距制御部３１はステップＳ３において算出された中央輝度評価値Ｖの情報を測距演算部３２から受けとり、この中央輝度評価値Ｖが０以下（Ｖ≦０）か、又は、中央輝度評価値Ｖが０を超える（Ｖ＞０）かを判断をする（Ｓ４）。ステップＳ４において測距制御部３１がＶ≦０であると判断した場合は、外側の測距エリアに対して中央側の測距エリアの輝度が充分な通常状態として採光終了判定エリア（後述するステップＳ７において採光の終了を決定するための判定対象として最適な最適測距エリア）を全部の測距エリア（全測距エリア）Ａ_ａ，Ａ_ｂ，Ａ_ｃ，Ａ_ｄ，Ａ_ｅと認定する（Ｓ５）。一方、ステップＳ４において測距制御部３１がＶ＞０であると判断した場合は、外側の測距エリアに対して中央側の測距エリアの輝度が不足な特殊環境状態として採光終了判定エリアを中央の測距エリア（中央測距エリア）Ａ_ｃと認定する（Ｓ６）。
【００２８】
すなわち、全ての測距エリアのうち中央側の測距エリアの光量が外側の測距エリアの光量よりも相対的に低いか否かをステップＳ４において判定し、中央側の測距エリアの光量が外側の測距エリアの光量よりも相対的に低くないときは、ステップＳ５おいて採光終了判定エリアを全測距エリアとし、中央側の測距エリアの光量が外側の測距エリアの光量よりも相対的に低いときは、ステップＳ６おいて採光終了判定エリアを中央側の測距エリアとする。なお、ここでは中央側の測距エリアを測距エリアＡ_ｃのみとしたが、これに限られるものではなく、適宜複数の測距エリアとしてよい。
【００２９】
測距制御部３１はステップＳ５又はステップＳ６で認定した採光終了判定エリアをメモリ３３に記憶させる（Ｓ７）。
【００３０】
つぎに、測距制御部３１は再度測距部４に被写体の測距領域２２に含まれる部分からの光を採光させる（Ｓ８）。このとき、測距制御部３１はステップＳ１における１度めの予備的な採光のときよりも採光時間を長くとるようにする。具体的には、ステップＳ７において記憶された採光終了判定エリアが全測距エリアである場合はこの全測距エリアＡ_ａ，Ａ_ｂ，Ａ_ｃ，Ａ_ｄ，Ａ_ｅに属する各センサ素子Ｐ_１，Ｐ_２・・・Ｐ_２００の輝度値Ｌ_１，Ｌ_２・・・Ｌ_２００のうち、所定数のセンサ素子の蓄積電荷（蓄積光量）が飽和したときをもって採光を終了させ、ステップＳ７において記憶された採光終了判定エリアが中央測距エリアである場合はこの中央測距エリアＡ_ｃに属する各センサ素子Ｐ_８１，Ｐ_８２・・・Ｐ_１２０の輝度値Ｌ_８１，Ｌ_８２・・・Ｌ_１２０のうち、所定数のセンサ素子の蓄積電荷（蓄積光量）が飽和したときをもって採光を終了させる。すなわち、採光終了判定エリアの中で最も明るい箇所に対応するセンサ素子が最大光量になったときに採光を終了させるため、コントラストを最大化にすることができる。ステップＳ８において採光された光が各センサ素子Ｐ_１，Ｐ_２・・・Ｐ_２００において電荷に変換され、この電荷に基づいて測距制御部３１は各センサ素子Ｐ_１，Ｐ_２・・・Ｐ_２００ごとの輝度値Ｌ_１，Ｌ_２・・・Ｌ_２００を更新する（Ｓ９）。
【００３１】
なお、ここでの所定数とは単数であっても複数であってもよいが、一定数が単数又は複数であってもその数が小さい場合は、短時間で測距を行うことができる。また、ここではセンサ素子の蓄積電荷（蓄積光量）が飽和したときをもって採光を終了させることとしたが、これに限られず、例えばセンサ素子の蓄積電荷（蓄積光量）が任意の一定値に達したときをもって採光を終了させることとしてもよい。
【００３２】
つぎに、測距制御部３１は各測距エリアＡ_ａ，Ａ_ｂ，Ａ_ｃ，Ａ_ｄ，Ａ_ｅごとに被写体距離Ｄ_ａ，Ｄ_ｂ，Ｄ_ｃ，Ｄ_ｄ，Ｄ_ｅを測定する（Ｓ１０）。ステップＳ１０において測定された被写体距離Ｄ_ａ，Ｄ_ｂ，Ｄ_ｃ，Ｄ_ｄ，Ｄ_ｅを測距制御部３１は短い順（短い側から長い側）にソートする（Ｓ１１）。ここでは、短い順として例えばＤ_ｃ，Ｄ_ｄ，Ｄ_ｂ，Ｄ_ｅ，Ｄ_ａの順番にソートされたとする。
【００３３】
また、測距制御部３１は測距演算部３２にステップＳ９において更新された輝度値Ｌ_１，Ｌ_２・・・Ｌ_２００の情報を送り、測距演算部３２はこれらの輝度値Ｌ_１，Ｌ_２・・・Ｌ_２００から（２）式に基づいて各測距エリアＡ_ａ，Ａ_ｂ，Ａ_ｃ，Ａ_ｄ，Ａ_ｅのコントラスト値Ｃ_ａ，Ｃ_ｂ，Ｃ_ｃ，Ｃ_ｄ，Ｃ_ｅを算出する（Ｓ１２）。
【００３４】
【数２】

【００３５】
（但し、ここでのＬ_ｉは測距エリアＡ_ｋ（ここでは、ｋ＝ａ，ｂ，ｃ，ｄ，ｅ）に属するセンサ素子の輝度値）
（２）式は、各測距エリア内における全部のセンサ素子について、それぞれ隣り合う２つのセンサ素子の輝度値の差分値の総和を示したものである。
【００３６】
つぎに、測距制御部３１はステップＳ１２において算出された各測距エリアＡ_ａ，Ａ_ｂ，Ａ_ｃ，Ａ_ｄ，Ａ_ｅのコントラスト値Ｃ_ａ，Ｃ_ｂ，Ｃ_ｃ，Ｃ_ｄ，Ｃ_ｅの情報を測距演算部３２から受けとり、このコントラスト値Ｃ_ａ，Ｃ_ｂ，Ｃ_ｃ，Ｃ_ｄ，Ｃ_ｅをステップＳ１１においてソートされた被写体距離の順番に対応付けてコントラスト値をＣ_ｃ，Ｃ_ｄ，Ｃ_ｂ，Ｃ_ｅ，Ｃ_ａの順にソートし（Ｓ１３）、メモリ３３に記憶させる（Ｓ１４）。
【００３７】
測距制御部３１は合焦するときに用いる最終被写体距離Ｄ_ｆを初期化してＤ_ｆ＝０とする（Ｓ１５）。つぎに、測距制御部３１はステップＳ１４において記憶させたコントラスト値のうち一番最初のコントラスト値Ｃ_ｃ（被写体距離が一番短い測距エリアＡ_ｃのコントラスト値）が所定値Ｃ_ｆより大きいか否かを判断する（Ｓ１６）。
【００３８】
ステップＳ１６において測距制御部３１がコントラスト値Ｃ_ｃが所定値Ｃ_ｆより大きいと判断した場合は、最終被写体距離Ｄ_ｆをＤ_ｆ＝Ｄ_ｃ（コントラスト値Ｃ_ｃが対応する被写体距離）として更新する（Ｓ１７）。
【００３９】
一方、ステップＳ１６においてコントラスト値Ｃ_ｃが所定値Ｃ_ｆより大きくないと判断した場合は、測距制御部３１はステップＳ１４において記憶させたコントラスト値の順番において、コントラスト値Ｃ_ｃの次に位置するコントラスト値があるか否かを判断する（Ｓ１８）。ステップ１８においてコントラスト値Ｃ_ｃの次に位置するコントラスト値Ｃ_ｄがあると判断した測距制御部３１は、コントラスト値Ｃ_ｄ（ステップＳ１３において記憶させたコントラスト値のうち２番めに相当するコントラスト値）についてステップＳ１６を繰り返す。すなわち、測距制御部３１はコントラスト値Ｃ_ｄが所定値Ｃ_ｆより大きいか否かを判断し（Ｓ１６）、コントラスト値Ｃ_ｄが所定値Ｃ_ｆより大きいと判断した場合は、最終被写体距離Ｄ_ｆをＤ_ｆ＝Ｄ_ｄとして更新する（Ｓ１７）一方、コントラスト値Ｃ_ｄが所定値Ｃ_ｆより大きくないと判断した場合は、ステップＳ１８を経てステップＳ１６を繰り返す。
【００４０】
このようにして、コントラスト値Ｃ_ｋが所定値Ｃ_ｆより大きい（所定値Ｃ_ｆを充足している）と判断されるまで、ステップＳ１４において記憶させた順番（被写体距離が短い側の測距エリアのコントラスト値から長い側の測距エリアのコントラスト値の順番）に従って各コントラスト値をステップＳ１６において所定値Ｃ_ｆと比較していき、コントラスト値Ｃ_ｋが所定値Ｃ_ｆより大きいと判断されたところで、ステップＳ１７において最終被写体距離Ｄ_ｆをＤ_ｆ＝Ｄ_ｋ（コントラスト値Ｃ_ｋに対応する被写体距離Ｄ_ｋ）として更新する。
【００４１】
ステップＳ１７において最終被写体距離Ｄ_ｆを更新した場合、又は、ステップＳ１６においてコントラスト値Ｃ_ａ（ステップＳ１４において記憶させたコントラスト値のうち一番最後のコントラスト値）が所定値Ｃ_ｆより大きくないと判断しステップＳ１８において次に位置するコントラスト値がないと判断した場合は、測距制御部３１は最終被写体距離Ｄ_ｆが０か否かを判断する（Ｓ１９）。
【００４２】
ステップＳ１９において最終被写体距離Ｄ_ｆが０でないと判断した場合は、測距制御部３１は更新された被写体距離Ｄ_ｋを最終被写体距離Ｄ_ｆ（合焦の基準として最適な最適被写体距離）として出力する（Ｓ２０）。このステップＳ２０において出力された最終被写体距離Ｄ_ｆに基づいてカメラ１は自動合焦を行う。
【００４３】
一方、ステップＳ１９において最終被写体距離Ｄ_ｆが０であると判断した場合は、測距制御部３１は測距の無効を出力する（Ｓ２１）。この場合は、カメラ１は測距不能として自動合焦を行わない。
この実施の形態に係る測距装置では、中央輝度評価値Ｖに基づいて、Ｖ≦０であると判断した場合は採光終了判定エリアを全測距エリアＡ_ａ，Ａ_ｂ，Ａ_ｃ，Ａ_ｄ，Ａ_ｅと認定し、Ｖ＞０であると判断した場合は採光終了判定エリアを中央測距エリアＡ_ｃとしたので、中央において光量が不足している場合は受光時間を長くすることによって必要な光量を得ることができる。これによって、コントラストを大きくとることができるようになるため、例えば夜景を背景にしたポートレート撮影等遠くの背景のコントラストが高い一方で近くの人物等の被写体のコントラストが低い場合においても、可能な限り近くの被写体までの距離を選択する測距を行うことができる。また、例えば日陰等の比較的暗い場所におけるポートレート撮影等であっても、背景側ではなく人物等の近くの被写体側に合焦しやすくなる。
【００４４】
また、センサ素子Ｐ_１，Ｐ_２・・・Ｐ_２００は同期して前記採光を行うため、従来の技術のように、各センサ素子を個別に制御する必要がなく装置の構造を簡単にすることができ、コストの低減を図ることができる。
【００４５】
さらに、センサ素子Ｐ_１，Ｐ_２・・・Ｐ_２００における採光は予備的な採光を含めて２回のみであるため、従来の技術のように、測距に長い時間を要せず利便性に優れている。
【００４６】
また、本実施の形態の他の例として、採光終了判定エリアをユーザが選択できるようにしてもよい。すなわち、上述の実施の形態では、ステップＳ１〜Ｓ６の動作において測距装置２１が自動的に採光終了判定エリアを決定するようにしたが、この自動決定に加えてユーザにおいてもその採光終了判定エリアを選択できるように構成する。
【００４７】
この他の例では、操作部８に通常モード又は夜景モードを切り換えるモード選択手段としてのモード選択ボタンを含み、このモード選択ボタンはカメラ１の背面に設けられている（図示略）。ユーザはこのモード選択ボタンによって通常モードと夜景モードとのうち一方を選択することができるようになっている。また、このモード選択ボタンは制御回路３０に接続されて、通常モード又は夜景モードのいずれのモードが選択されているかの情報を制御回路３０に提供するようになっている。
【００４８】
このような構成において、測距装置２１の動作について説明すると、図８に示すように、シャッターボタン９が半押しされたことにより測距開始信号を受けた測距制御部３１は、まずモード選択ボタンによって選択されているモードが通常モードか夜景モードかを判断する（Ｓ１０１）。ステップＳ１０１において、夜景モードが選択されていると判断した場合は、測距制御部３１はステップＳ６に移行し、特殊環境状態として採光終了判定エリアを中央の測距エリアＡ_ｃと認定する。続いて、ステップＳ７以降の処理を行う。
【００４９】
一方、ステップＳ１０１において、通常モードが選択されていると判断した場合は、測距制御部３１はステップＳ１に移行し、測距部４に一定時間において被写体の測距領域２２に含まれる部分からの光を採光する。つぎに、ステップＳ２において各センサ素子Ｐ_１，Ｐ_２・・・Ｐ_２００ごとの輝度値Ｌ_１，Ｌ_２・・・Ｌ_２００を取得し、これらの輝度値Ｌ_１，Ｌ_２・・・Ｌ_２００に基づいてステップＳ３において中央輝度評価値Ｖを算出した結果、ステップＳ４〜Ｓ６において採光終了判定エリアを認定する。続いて、ステップＳ７以降の処理を行う。
【００５０】
この他の例に係る測距装置では、通常モード又は夜景モードを切り換えるモード選択ボタンが設けられ、モード選択ボタンにより夜景モードが選択されている場合は、外側の測距エリアの光量に対する中央側の測距エリアの光量の相対的な比較を行わずに特殊環境状態として、採光終了判定エリアを中央の測距エリアＡ_ｃとしたので、ユーザが、例えば夜景を背景にしたポートレート撮影等近くの人物等の被写体のコントラストが背景のコントラストより低いと感じた場合等に、確実に可能な限り近くの被写体までの距離を選択する測距を行わせることができ、ユーザの意図を反映することが可能となる。したがって、より状況に合わせて柔軟に対応でき、例えば夜景等に適した撮影ができるようになる。
【００５１】
また、上述の他の例から測距装置２１が自動的に採光終了判定エリアを決定する自動決定に関するステップＳ１〜Ｓ６を除いて、ユーザが採光終了判定エリアを選択するのみの構成であっても構わない。
【００５２】
【発明の効果】
本発明は、以上説明したよう構成したので、構造が簡単で、かつ短時間で適切な被写体までの距離の測定を行うことができる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係る測距装置を備えたカメラの正面斜視図である。
【図２】測距装置の２眼測距センサの斜視図である。
【図３】図２の２眼測距センサを模式的に示す断面図である。
【図４】ファインダの視野枠内を示す図である。
【図５】測距領域と各センサ素子の関係を説明する図である。
【図６】測距装置の概略構成を示すブロック図である。
【図７】測距装置の測距動作を示すフローチャートである。
【図８】測距装置の測距動作の他の例を示すフローチャートである。
【符号の説明】
４ 測距部
５ ファインダ
１０ ２眼測距センサ
２０ 視野枠
２１ 測距装置
２２ 測距領域
３０ 制御回路（制御部）
Ａ_ａ、Ａ_ｂ、Ａ_ｃ、Ａ_ｄ、Ａ_ｅ 測距エリア
Ｐ_１，Ｐ_２・・・Ｐ_２００ センサ素子[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a passive distance measuring apparatus used in a camera to measure a distance based on light from a subject.
[0002]
[Prior art]
2. Description of the Related Art As a distance measuring method used for an automatic focusing (AF) mechanism of a camera, a passive method based on a triangulation method has been conventionally known. In the passive method, the distance is measured using the contrast (luminance difference) of the subject. May cause the AF mechanism to operate so as to focus on a background with high contrast.
[0003]
In order to solve such a problem, for example, a distance measuring device that measures a distance by repeating scanning while changing an exposure time or a device that measures a distance by varying an exposure time for each sensor element has been devised. (For example, see Patent Documents 1 and 2).
[0004]
[Patent Document 1]
JP 2001-108892 A
[Patent Document 2]
JP-A-10-186460
[0005]
[Problems to be solved by the invention]
However, when scanning is repeated while changing the exposure time, the exposure time becomes longer, so that it takes time to measure the distance to the subject and focus, and the user needs to wait during that time. Chip. Further, when the exposure time is made different for each sensor element, it is necessary to individually drive a large number of sensor elements, which complicates the structure and control of the distance measuring device and causes an increase in cost.
[0006]
The present invention has been made in view of such a problem, and an object of the present invention is to provide a distance measuring apparatus having a simple structure and capable of measuring a distance to an appropriate subject in a short time.
[0007]
[Means for Solving the Problems]
In order to solve such a problem, an invention according to claim 1 has a distance measuring device having a plurality of sensor elements that collect light from a subject corresponding to a distance measuring region shown in a field frame in a finder. And a control unit for controlling the distance measuring unit, wherein the distance measuring area is divided into a plurality of distance measuring areas, and the control unit performs the lighting by synchronizing the sensor elements to each of the plurality of distance measuring areas. Based on the distribution of the light quantity accumulated in the sensor element in each of the distance measurement areas, the subject distance is measured for each of the distance measurement areas, and based on the accumulated light quantity, each of the distance measurement areas is measured. Calculate an index value representing contrast, based on the index value, determine any one of the ranging areas as the optimal ranging area, and the subject distance for the ranging area determined as the optimal ranging area, Optimal subject distance The distance measuring unit performs preliminary lighting by each of the sensor elements prior to the lighting, and the control unit performs a total measurement obtained based on the preliminary lighting. For the light quantity distribution in the distance area, it is determined whether or not the light quantity in the center distance measurement area of the entire distance measurement areas is relatively lower than the light quantity in the outer distance measurement area. Is relatively lower than the outer light amount, the lighting for measuring the subject distance is performed until a predetermined number of sensor elements among the sensor elements belonging to the center-side ranging area are saturated, When the light amount on the center side is not relatively lower than the light amount on the outside, a predetermined number of sensor elements among the sensor elements belonging to the entire ranging area saturate lighting for measuring the subject distance. Let go The distance measurement unit is controlled as described above, and the determination of the optimum distance measurement area based on the index value is performed by setting the index value in a predetermined order from the distance measurement area on the short side of the subject distance to the distance measurement area on the long side. The determination is performed by determining whether or not the value is satisfied.
[0008]
According to a second aspect of the present invention, in the first aspect of the present invention, the apparatus further comprises a mode selection unit that selects one of a night scene mode and a normal mode, and the control unit controls the night scene mode by the mode selection unit. Is selected, the sensor element belonging to the center-side ranging area is not compared with the light quantity of the center-side ranging area and the light amount of the outer ranging area. Lighting for measuring the subject distance is performed until a predetermined number of sensor elements are saturated.
[0009]
According to a third aspect of the present invention, in the first or second aspect, the control unit performs the preliminary lighting in a shorter time than the lighting for measuring the subject distance. It is characterized by performing.
[0010]
According to a fourth aspect of the present invention, a distance measuring section having a plurality of sensor elements for collecting light from a subject corresponding to a distance measuring area shown in a field frame in a finder, and the distance measuring section is controlled. A control unit, comprising a mode selection unit for selecting one of a night scene mode and a normal mode, wherein the distance measurement area is divided into a plurality of distance measurement areas, and the control unit is configured such that the sensor elements are synchronized with each other. The amount of light accumulated in each sensor element by performing daylighting, based on the distribution in each of the ranging areas, and measuring the subject distance for each of the ranging areas, based on the accumulated amount of light, Calculating an index value representing a contrast for each of the distance measurement areas; determining one of the distance measurement areas as an optimum distance measurement area based on the index value; and determining the distance measurement area determined as the optimum distance measurement area. about In the distance measuring device that outputs the subject distance as an optimal subject distance, when the night view mode is selected by the mode selection means, the control unit transmits a light for measuring the subject distance to the center. The predetermined number of sensor elements among the sensor elements belonging to the side ranging area are saturated, and when the normal mode is selected by the mode selection means, lighting for measuring the subject distance is performed. The distance measuring unit is controlled so that a predetermined number of sensor elements among the sensor elements belonging to the entire distance measuring area are saturated, and the determination of the optimal distance measuring area based on the index value is performed by determining the subject distance. Is determined by determining whether the index value satisfies a predetermined value in order from the shorter distance measuring area to the longer distance measuring area.
[0011]
According to a fifth aspect of the present invention, in the first aspect of the present invention, the predetermined number of sensor elements is one sensor element.
[0012]
According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the distance measuring unit includes a binocular distance measuring sensor, and the plurality of the plurality of distance measuring units are included in the binocular distance measuring sensor. Are arranged linearly, and the control unit measures the subject distance for each of the distance measurement areas based on the light amount distribution in the corresponding distance measurement area between the two-lens distance measurement sensors. It is characterized by the following.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 shows a camera provided with a distance measuring device according to an embodiment of the present invention. At the center of the front 2 of the camera 1, there is provided an image pickup lens 3 for inputting photographing light. And a strobe 6 used when shooting at low illuminance. Further, a shutter button 9 as a part of the operation unit 8 (see FIG. 6) is provided on the upper surface 7 of the camera 1.
[0015]
The distance measuring unit 4 includes the twin-lens distance measuring sensor 10 shown in FIGS. The two-lens distance measuring sensor 10 includes a first distance measuring unit 11 and a second distance measuring unit 12, and each of the first distance measuring unit 11 and the second distance measuring unit 12 includes, for example, 200 photodiodes. Some sensor element P ₁ , P ₂ ... P ₂₀₀ Are provided with line image sensors 13 and 14 and lenses 15 and 16 arranged linearly. The line image sensors 13 and 14 are arranged at regular intervals on the same straight line, and lenses 15 and 16 are provided in front of the line image sensors 13 and 14, respectively. It is to be noted that other distance measuring sensors are also possible, but the two-lens distance measuring sensor is inexpensive, and one in which a plurality of sensor elements are linearly arranged has a simple structure among the two-lens distance measuring sensors. Therefore, cost can be reduced.
[0016]
In the first distance measuring unit 11 and the second distance measuring unit 12, light from the subject is collected through the lenses 15 and 16, and this light is converged with the positions of the line image sensors 13 and 14 as focusing planes. Element P ₁ , P ₂ ... P ₂₀₀ Is converted into electric charge by the sensor element P ₁ , P ₂ ... P ₂₀₀ Each time, the charge is accumulated. At this time, each sensor element P ₁ , P ₂ ... P ₂₀₀ Operate synchronously, and each sensor element P ₁ , P ₂ ... P ₂₀₀ In both cases, the lighting time is the same.
[0017]
As shown in FIG. 4, an AF frame 23 indicating a distance measuring area 22 of a distance measuring device 21 (see FIG. 6) is displayed at the center of a field frame 20 of the finder 5. The user adjusts the focus by pressing the shutter button 9 halfway while adjusting the camera 1 so that the subject to be focused is included in the AF frame 23.
[0018]
As shown in FIG. 5, the ranging area 22 has five ranging areas A. _a , A _b , A _c , A _d , A _e And the distance measurement area A _a Has a sensor element P ₁ , P ₂ ..P ₄₀ But distance measurement area A _b Has a sensor element P ₄₁ , P ₄₂ ..P ₈₀ But distance measurement area A _c Has a sensor element P ₈₁ , P ₈₂ ..P ₁₂₀ But distance measurement area A _d Has a sensor element P ₁₂₁ , P ₁₂₂ ..P ₁₆₀ But distance measurement area A _e Has a sensor element P ₁₆₁ , P ₁₆₂ ..P ₂₀₀ Correspond to each other. Here, the distance measurement area is divided into five, but the number is not limited to this and may be an arbitrary number as long as it is n / 2 or less.
[0019]
The distance measuring device 21 calculates a distance (subject distance) from the camera 1 to the subject based on an image obtained by receiving light from a portion included in the distance measuring area 22 of the subject. Specifically, each sensor element P of the line image sensor 13 of the first distance measuring unit 11 of the two-lens distance measuring sensor 10 is determined using a triangulation method. ₁ , P ₂ ... P ₂₀₀ Of the amount of light (charge) accumulated in each of the sensor elements P of the line image sensor 14 of the second distance measuring unit 12 ₁ , P ₂ ... P ₂₀₀ The subject distance is calculated from the relative position deviation from the distribution of the amount of light (charge) accumulated in.
[0020]
FIG. 6 shows a schematic configuration of a distance measuring device provided in the camera 1. Reference numeral 21 denotes a distance measurement device, 30 denotes a control circuit as a control unit, 31 denotes a distance measurement control unit, 32 denotes a distance measurement calculation unit, 33 denotes a memory, 8 denotes an operation unit, 34 denotes a focus lens, 35 denotes a focus driver, 36 Represents an imaging unit.
[0021]
The control circuit 30 controls the entire operation of the camera 1 such as automatic focusing (AF), and has a distance measurement control unit 31, a distance measurement calculation unit 32, and a memory 33. The distance measurement control unit 31 includes a ground voltage (GRD), a synchronization signal (CLK), and a sensor element P. ₁ , P ₂ ... P ₂₀₀ The control of the distance measuring unit 4 is performed by sending control signals such as potential reading (AFDATA), integration start / end control (CTRL), and constant voltage (VDD) to the distance measuring unit 4.
[0022]
The focus driver 35 drives the focus lens 34 in the optical axis direction according to a signal sent from the control circuit 30 based on the distance measurement result of the distance measurement device 21 so that the positions of the line image sensors 13 and 14 coincide with the focal plane. Let it. Further, the imaging unit 36 performs an imaging process according to an instruction from the control circuit 30.
[0023]
Next, the operation of the distance measuring device 21 will be described. FIG. 7 is a flowchart showing the distance measuring operation of the distance measuring device 21.
[0024]
Upon receiving the distance measurement start signal due to the half-press of the shutter button 9, the distance measurement control unit 31 preliminarily collects light from a portion included in the distance measurement area 22 of the subject to the distance measurement unit 4 for a predetermined time. (S1). The light collected in step S1 is applied to each sensor element P ₁ , P ₂ ... P ₂₀₀ Are converted into electric charges, and from this electric charge, the distance measurement control unit 31 _a , A _b , A _c , A _d , A _e Element P as an index value representing the contrast of each sensor ₁ , P ₂ ... P ₂₀₀ Brightness value L for each _i (Sensor element P ₁ The luminance value of L ₁ And similarly, each sensor element P ₂ ... P ₂₀₀ Are respectively L ₂ ... L ₂₀₀ Is obtained (S2). The distance measurement control unit 31 sends the luminance value L to the distance measurement calculation unit 32. ₁ , L ₂ ... L ₂₀₀ And the distance calculating section 32 sends these luminance values L ₁ , L ₂ ... L ₂₀₀ Then, the central brightness evaluation value V is calculated based on the equation (1) (S3).
[0025]
(Equation 1)

[0026]
In the equation (1), the second term indicates the sum of the luminance values of the sensor elements, while the first term indicates the sum of the luminance values of the sensor elements located in the central distance measuring area. The brightness value of a certain sensor element is weighted, and the larger the brightness value of the sensor element in the outer ranging area is, the greater the brightness value of the sensor element in the center ranging area is. It has become.
[0027]
Next, the distance measurement control unit 31 receives information on the central luminance evaluation value V calculated in step S3 from the distance measurement calculation unit 32, and determines whether the central luminance evaluation value V is equal to or less than 0 (V ≦ 0), or It is determined whether the luminance evaluation value V exceeds 0 (V> 0) (S4). If the distance measurement control unit 31 determines in step S4 that V ≦ 0, it is determined that the brightness of the center distance measurement area is sufficient for the outer distance measurement area, and that the lighting end determination area (step described later) In step S7, the optimum distance measurement area (the optimum distance measurement area) as a determination target for determining the end of the lighting is changed to all the distance measurement areas (all distance measurement areas) A. _a , A _b , A _c , A _d , A _e (S5). On the other hand, if the distance measurement control unit 31 determines in step S4 that V> 0, the lighting end determination area is determined as a special environment state in which the brightness of the center distance measurement area is insufficient with respect to the outer distance measurement area. Center distance measurement area (center distance measurement area) A _c (S6).
[0028]
That is, it is determined in step S4 whether or not the light quantity of the center-side ranging area is relatively lower than the light quantity of the outer ranging area in all the ranging areas. If the light amount is not relatively lower than the light amount of the outer distance measuring area, the lighting end determination area is set as the entire distance measuring area in step S5, and the light amount of the central distance measuring area is smaller than the light amount of the outer distance measuring area. If the distance is relatively low, the daylighting end determination area is set as the center-side distance measurement area in step S6. Here, the distance measurement area on the center side is referred to as distance measurement area A. _c However, the present invention is not limited to this, and a plurality of ranging areas may be appropriately used.
[0029]
The distance measurement control unit 31 causes the memory 33 to store the daylighting end determination area recognized in step S5 or step S6 (S7).
[0030]
Next, the distance measurement control unit 31 causes the distance measurement unit 4 to again emit light from a portion included in the distance measurement area 22 of the subject (S8). At this time, the distance measurement control unit 31 sets a longer lighting time than in the first preliminary lighting in step S1. More specifically, if the lighting end determination area stored in step S7 is the entire ranging area, the entire ranging area A _a , A _b , A _c , A _d , A _e Each sensor element P belonging to ₁ , P ₂ ... P ₂₀₀ Brightness value L ₁ , L ₂ ... L ₂₀₀ The lighting is terminated when the accumulated charge (accumulated light amount) of a predetermined number of sensor elements is saturated. If the lighting end determination area stored in step S7 is the central ranging area, the central ranging area A _c Each sensor element P belonging to ₈₁ , P ₈₂ ... P ₁₂₀ Brightness value L ₈₁ , L ₈₂ ... L ₁₂₀ Lighting is terminated when the accumulated charge (accumulated light amount) of a predetermined number of sensor elements is saturated. That is, when the sensor element corresponding to the brightest part in the lighting end determination area has the maximum light amount, the lighting is terminated, so that the contrast can be maximized. The light collected in step S8 is ₁ , P ₂ ... P ₂₀₀ Are converted to electric charges, and based on the electric charges, the distance measurement control unit 31 ₁ , P ₂ ... P ₂₀₀ Brightness value L for each ₁ , L ₂ ... L ₂₀₀ Is updated (S9).
[0031]
Here, the predetermined number may be singular or plural. However, even if the fixed number is singular or plural, if the number is small, distance measurement can be performed in a short time. Here, the lighting is terminated when the accumulated charge (accumulated light quantity) of the sensor element is saturated. However, the present invention is not limited to this. For example, the accumulated charge (accumulated light quantity) of the sensor element reaches an arbitrary constant value. Lighting may be terminated at times.
[0032]
Next, the distance measurement control unit 31 sets each distance measurement area A _a , A _b , A _c , A _d , A _e Subject distance D for each _a , D _b , D _c , D _d , D _e Is measured (S10). The subject distance D measured in step S10 _a , D _b , D _c , D _d , D _e Are sorted in the short order (from the short side to the long side) (S11). Here, for example, D _c , D _d , D _b , D _e , D _a Is sorted in the order
[0033]
Further, the distance measurement control unit 31 sends the luminance value L updated in step S9 to the distance measurement calculation unit 32. ₁ , L ₂ ... L ₂₀₀ And the distance calculating section 32 sends these luminance values L ₁ , L ₂ ... L ₂₀₀ From each of the distance measurement areas A based on equation (2). _a , A _b , A _c , A _d , A _e Contrast value C _a , C _b , C _c , C _d , C _e Is calculated (S12).
[0034]
(Equation 2)

[0035]
(However, here L _i Is the distance measurement area A _k (Here, the luminance value of the sensor element belonging to k = a, b, c, d, e)
Equation (2) shows the sum of the difference values of the luminance values of two adjacent sensor elements for all sensor elements in each ranging area.
[0036]
Next, the distance measurement control unit 31 calculates each of the distance measurement areas A calculated in step S12. _a , A _b , A _c , A _d , A _e Contrast value C _a , C _b , C _c , C _d , C _e Is received from the distance calculation unit 32, and the contrast value C _a , C _b , C _c , C _d , C _e Is associated with the order of the subject distances sorted in step S11, and the contrast value is set to C. _c , C _d , C _b , C _e , C _a (S13) and stored in the memory 33 (S14).
[0037]
The distance measurement control unit 31 determines the final subject distance D used when focusing. _f To initialize D _f = 0 (S15). Next, the distance measurement control unit 31 sets the first contrast value C among the contrast values stored in step S14. _c (Area A with the shortest subject distance _c Is a predetermined value C _f It is determined whether or not it is larger than (S16).
[0038]
In step S16, the distance measurement control unit 31 sets the contrast value C _c Is the predetermined value C _f If it is determined to be larger than the final subject distance D _f To D _f = D _c (Contrast value C _c Is updated as the corresponding subject distance) (S17).
[0039]
On the other hand, in step S16, the contrast value C _c Is the predetermined value C _f When it is determined that the contrast value is not larger, the distance measurement control unit 31 determines the contrast value C in the order of the contrast value stored in step S14. _c It is determined whether or not there is a contrast value located next to (S18). In step 18, the contrast value C _c Value C located next to _d The distance measurement control unit 31 that has determined that there is _d Step S16 is repeated for (the second contrast value among the contrast values stored in step S13). That is, the distance measurement control unit 31 sets the contrast value C _d Is the predetermined value C _f It is determined whether or not the contrast value is greater than the contrast value C (S16). _d Is the predetermined value C _f If it is determined to be larger than the final subject distance D _f To D _f = D _d (S17), while the contrast value C _d Is the predetermined value C _f If it is determined that it is not larger, step S16 is repeated via step S18.
[0040]
Thus, the contrast value C _k Is the predetermined value C _f Greater than (predetermined value C _f Are satisfied in the order stored in step S14 (the order from the contrast value of the distance measurement area on the shorter distance to the distance measurement area on the longer distance area) in step S14. In step S16, the predetermined value C _f And the contrast value C _k Is the predetermined value C _f When it is determined that the distance is larger than the final object distance D in step S17. _f To D _f = D _k (Contrast value C _k Subject distance D corresponding to _k ).
[0041]
In step S17, the final subject distance D _f Has been updated, or in step S16, the contrast value C _a (The last contrast value among the contrast values stored in step S14) is the predetermined value C _f When it is determined that the contrast value is not larger than the threshold value and it is determined in step S18 that there is no next contrast value, the distance measurement control unit 31 determines that the final subject distance D _f Is determined to be 0 (S19).
[0042]
In step S19, the final subject distance D _f Is determined to be not 0, the distance measurement control unit 31 updates the subject distance D _k Is the final subject distance D _f It is output as (the optimum optimal subject distance as a reference for focusing) (S20). The final subject distance D output in step S20 _f The camera 1 performs automatic focusing based on.
[0043]
On the other hand, in step S19, the final subject distance D _f Is determined to be 0, the distance measurement control unit 31 outputs the invalidity of the distance measurement (S21). In this case, the camera 1 determines that distance measurement is impossible and does not perform automatic focusing.
In the distance measuring apparatus according to this embodiment, if it is determined that V ≦ 0 based on the central luminance evaluation value V, the lighting end determination area is set to the entire distance measuring area A. _a , A _b , A _c , A _d , A _e When it is determined that V> 0, the lighting end determination area is set to the center ranging area A. _c Therefore, when the light quantity is insufficient at the center, the necessary light quantity can be obtained by lengthening the light receiving time. As a result, the contrast can be increased, and therefore, even when the contrast of a distant background is high while the contrast of a subject such as a nearby person is low, for example, portrait shooting with a night view as the background, this is possible. Distance measurement for selecting a distance to a subject as close as possible can be performed. Further, for example, even in portrait photography or the like in a relatively dark place such as a shade, it is easy to focus not on the background side but on a subject side near a person or the like.
[0044]
Also, the sensor element P ₁ , P ₂ ... P ₂₀₀ Since the lighting is performed in synchronization with each other, there is no need to individually control each sensor element as in the related art, so that the structure of the device can be simplified and the cost can be reduced.
[0045]
Further, the sensor element P ₁ , P ₂ ... P ₂₀₀ Since the lighting is only two times including the preliminary lighting, the distance measurement does not require a long time as in the related art, and is excellent in convenience.
[0046]
Further, as another example of the present embodiment, a user may be allowed to select a lighting end determination area. That is, in the above-described embodiment, the distance measuring device 21 automatically determines the lighting end determination area in the operations of steps S1 to S6. In addition to this automatic determination, the user also determines the lighting end determination area. Is configured to be selectable.
[0047]
In this other example, the operation unit 8 includes a mode selection button as mode selection means for switching between the normal mode and the night scene mode, and the mode selection button is provided on the back of the camera 1 (not shown). The user can select one of the normal mode and the night view mode by using the mode selection button. The mode selection button is connected to the control circuit 30 so as to provide the control circuit 30 with information on which of the normal mode and the night view mode is selected.
[0048]
In such a configuration, the operation of the distance measuring device 21 will be described. As shown in FIG. 8, the distance measurement control unit 31 that receives the distance measurement start signal when the shutter button 9 is half-pressed first selects the mode selection mode. It is determined whether the mode selected by the button is the normal mode or the night view mode (S101). If it is determined in step S101 that the night view mode has been selected, the distance measurement control unit 31 proceeds to step S6 and sets the lighting end determination area as the central distance measurement area A as a special environment state. _c Certified. Subsequently, the processing after step S7 is performed.
[0049]
On the other hand, if it is determined in step S101 that the normal mode has been selected, the distance measurement control unit 31 proceeds to step S1, and instructs the distance measurement unit 4 to return to the area included in the distance measurement area 22 of the subject for a predetermined time. The light is taken. Next, in step S2, each sensor element P ₁ , P ₂ ... P ₂₀₀ Brightness value L for each ₁ , L ₂ ... L ₂₀₀ And obtain these luminance values L ₁ , L ₂ ... L ₂₀₀ As a result of calculating the central luminance evaluation value V in step S3 based on the above, a lighting end determination area is recognized in steps S4 to S6. Subsequently, the processing after step S7 is performed.
[0050]
In the distance measuring apparatus according to this other example, a mode selection button for switching between a normal mode and a night scene mode is provided, and when the night scene mode is selected by the mode selection button, a center side with respect to the light amount of the outer distance measuring area is provided. As a special environment state without performing a relative comparison of the light amount of the ranging area, the lighting end determination area is set to the central ranging area A. _c Therefore, if the user feels that the contrast of a subject such as a nearby person is lower than the contrast of the background, for example, in portrait shooting against the background of a night view, the distance to the subject as close as possible is ensured. The selected distance measurement can be performed, and the intention of the user can be reflected. Therefore, it is possible to flexibly respond to the situation, and for example, it is possible to perform shooting suitable for a night view or the like.
[0051]
In addition, even if the configuration is such that the user only selects the lighting end determination area, except for steps S1 to S6 relating to the automatic determination in which the distance measuring device 21 automatically determines the lighting end determination area from the other examples described above. I do not care.
[0052]
【The invention's effect】
Since the present invention is configured as described above, it has a simple structure and can measure an appropriate distance to a subject in a short time.
[Brief description of the drawings]
FIG. 1 is a front perspective view of a camera provided with a distance measuring device according to an embodiment of the present invention.
FIG. 2 is a perspective view of a two-lens distance measuring sensor of the distance measuring device.
FIG. 3 is a sectional view schematically showing the twin-lens distance measuring sensor of FIG. 2;
FIG. 4 is a view showing the inside of a view frame of a finder;
FIG. 5 is a diagram illustrating a relationship between a distance measurement area and each sensor element.
FIG. 6 is a block diagram illustrating a schematic configuration of a distance measuring device.
FIG. 7 is a flowchart showing a distance measuring operation of the distance measuring device.
FIG. 8 is a flowchart showing another example of the distance measuring operation of the distance measuring device.
[Explanation of symbols]
4 Distance measuring unit
5 Finder
10 Two-lens distance measuring sensor
20 field frame
21 Distance measuring device
22 AF area
30 control circuit (control unit)
A _a , A _b , A _c , A _d , A _e Distance measurement area
P ₁ , P ₂ ... P ₂₀₀ Sensor element

Claims (6)

A distance measuring unit having a plurality of sensor elements that collects light from a subject corresponding to a distance measuring area shown in a field frame in a viewfinder, and a control unit that controls the distance measuring unit,
The ranging area is divided into a plurality of ranging areas,
The control unit measures the subject distance for each of the distance measurement areas based on the distribution of the amount of light accumulated in each of the sensor elements by the sensor elements taking light synchronously in each of the distance measurement areas. And, based on the accumulated light amount, calculate an index value representing the contrast of each of the distance measurement areas, based on the index value, determine one of the distance measurement areas as the optimal distance measurement area, In the distance measuring device that outputs the subject distance for the ranging area determined as the optimal ranging area, as an optimal subject distance,
The distance measurement unit performs preliminary lighting by each of the sensor elements prior to the lighting,
The controller may be configured such that, with respect to the light quantity distribution of the entire ranging area obtained based on the preliminary lighting, the light quantity of the central ranging area in the entire ranging area is the light quantity of the outer ranging area. It is determined whether or not the light amount on the center side is relatively lower than the light amount on the outer side. When a predetermined number of sensor elements among the sensor elements belonging to are saturated, and when the light amount on the center side is not relatively lower than the light amount on the outside, lighting for measuring the subject distance is performed. Along with controlling the distance measuring unit so that a predetermined number of sensor elements among the sensor elements belonging to the entire distance measuring area are saturated,
The determination of the optimum distance measurement area based on the index value may include determining whether or not the index value satisfies a predetermined value in order from the short distance measurement area to the long distance measurement area. A ranging device for a camera, characterized in that the measurement is performed by: A mode selecting means for selecting one of the night view mode and the normal mode is provided,
When the night view mode is selected by the mode selection unit, the control unit does not perform a relative comparison between the light amount for the center-side ranging area and the light amount for the outer ranging area. 2. The camera according to claim 1, wherein the lighting for measuring the subject distance is performed until a predetermined number of sensor elements among the sensor elements belonging to the center-side ranging area are saturated. Distance device. 3. The camera distance measuring device according to claim 1, wherein the control unit performs the preliminary lighting in a shorter time than the lighting for measuring the subject distance. 4. A distance measuring unit having a plurality of sensor elements for collecting light from a subject corresponding to a distance measuring area shown in a field frame in a viewfinder; a control unit for controlling the distance measuring unit; a night view mode and a normal mode And mode selection means for selecting one of the
The ranging area is divided into a plurality of ranging areas,
The control unit measures the subject distance for each of the distance measurement areas based on the distribution of the amount of light accumulated in each of the sensor elements by the sensor elements taking light synchronously in each of the distance measurement areas. And, based on the accumulated light amount, calculate an index value representing the contrast of each of the distance measurement areas, based on the index value, determine one of the distance measurement areas as the optimal distance measurement area, In the distance measuring device that outputs the subject distance for the ranging area determined as the optimal ranging area, as an optimal subject distance,
When the night view mode is selected by the mode selection means, the control unit emits light for measuring the subject distance to a predetermined number of sensor elements among sensor elements belonging to the center-side distance measurement area. Is performed until the normal mode is selected by the mode selection means, and a predetermined number of sensor elements among the sensor elements belonging to the entire distance measurement area emit light for measuring the subject distance. While controlling the distance measurement unit so that the measurement is performed until saturation is achieved,
The determination of the optimum distance measurement area based on the index value may include determining whether or not the index value satisfies a predetermined value in order from the short distance measurement area to the long distance measurement area. A ranging device for a camera, characterized in that the measurement is performed by: The camera distance measuring apparatus according to any one of claims 1 to 4, wherein the predetermined number of sensor elements is one sensor element. The ranging unit includes a binocular ranging sensor, and the plurality of sensor elements are linearly arranged in the binocular ranging sensor;
6. The apparatus according to claim 1, wherein the control unit measures the subject distance for each of the distance measurement areas based on a light amount distribution in a corresponding distance measurement area between the two-lens distance measurement sensors. The distance measuring device for a camera according to any one of claims 1 to 7.

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