JP3940016B2

JP3940016B2 - Electronic endoscope device capable of recording still images

Info

Publication number: JP3940016B2
Application number: JP2002114323A
Authority: JP
Inventors: 紀子太田; 俊一伊藤; 兼一入山
Original assignee: ペンタックス株式会社
Priority date: 2002-04-17
Filing date: 2002-04-17
Publication date: 2007-07-04
Anticipated expiration: 2022-04-17
Also published as: JP2003305005A

Description

【０００１】
【発明の属する技術分野】
本発明は、撮像素子を有するビデオスコープ（電子スコープ）と、撮像素子から読み出される画像信号に対して信号処理を施すプロセッサとを備えた電子内視鏡装置に関し、特に、静止画像の記録を実行するフリーズ動作に関する。
【０００２】
【従来の技術】
従来の電子内視鏡装置では、動画像をモニタへ表示するとともに、オペレータの操作に従ってフリーズ動作が実行可能である。すなわち、静止画像の記録処理が実行され、静止画像がメモリやビデオレコーダなどの記録装置に記録される。
【０００３】
電子内視鏡装置において静止画像を記録する場合、ビデオスコープの手ぶれや観察部位自体の動きなどにより、記録された静止画像に解像度、色ずれなどが生じ、画質が低下する恐れがある。特に、観察部位とビデオスコープ先端との距離が離れている状態、あるいは画像の拡大機能を利用してズーム撮影している場合、画質低下が顕著となる。このような問題を解決するため、フリーズ動作実行において、被写体へ照射する光量を増加させるとともに、電子シャッタのシャッタ速度を高速に設定する構成が知られている（特開平６−２９６５８０号、特開平１１−２４４２２９号および特開２００１−１００１１１号参照）。この場合、絞り全開動作やストロボ発光によって光量が増加され、その光量増加に応じてシャッタ速度が設定される。
【０００４】
【発明が解決しようとする課題】
上記の構成では、増加させる光量があらかじめ決定されており、適切な明るさの静止画像を記録するためには、順次記録される静止画像の輝度レベルを判断しながらシャッタ速度を調整する必要がある。また、フリーズ動作直前における絞りの開度が小さいと、絞り全開動作によって被写体への光量が瞬間的に過度に増加してしまい、適切な明るさの静止画像を得ることが難しい。
【０００５】
そこで本発明では、フリーズ動作を繰り返し実行することなく適切な明るさの静止画像を得ることができるとともに、フリーズ動作の最中において被写体観察に支障のない画像をモニタに表示することができる電子内視鏡装置および内視鏡用静止画像記録装置を得ることを目的とする。
【０００６】
【課題を解決するための手段】
本発明の電子内視鏡装置は、撮像素子を有するビデオスコープとビデオスコープおよび表示用モニタが接続されるプロセッサとを備えた電子内視鏡装置であって、プロセッサには、被写体像を表示するためのモニタが接続される。電子内視鏡装置は、被写体の動画像を表示するため、被写体に応じた画像信号を撮像素子から所定時間間隔毎に読み出して処理する動画像表示手段を有する。例えば、カラーテレビジョン方式としてＮＴＳＣ方式が適用される場合、動画像表示のため１／６０秒間隔で画像信号を読み出せばよい。また、電子内視鏡装置は、被写体を照明するため光源から放射される光の光量を調整する光量調整手段を有する。例えば、光量調整手段は絞りであり、光源とライトガイドなどの光伝達部材との間に介在するように絞りが配置される。また、絞りの代わりに液晶板（液晶シャッタ）や偏光板を配置してもよい。あるいは、光源から放射される光の発光量を制御するように発光制御制御回路を光量調整手段として設けてもよい。
【０００７】
モニタに表示される動画像の明るさを適切にするため、電子内視鏡装置は、表示される動画像の明るさが同一となるように光量調整手段を制御する自動調光処理手段を備えるのがよい。例えば、光量調子手段が絞りである場合、撮像素子から順次読み出される画像信号に基づいて輝度値を算出し、その輝度値と被写体像の適切な明るさを示す動画像基準輝度値とに基づいて絞りを開閉させればよい。輝度値は、被写体像の代表的明るさを示す輝度レベルの値であり、例えば明るさを１〜２５６段階に分けた場合、０〜２５５のいずれかの整数値で表される。輝度値としては、例えば被写体像全体の明るさ平均を示す輝度平均値が適用される。この場合、動画像基準輝度値としては、例えば１２０〜１４０のいずれかの値に設定すればよい。
【０００８】
電子内視鏡装置は、フリーズ動作を実行するため、オペレータにより操作される記録実行操作部材と、静止画像記録手段とを備える。例えば、ビデオスコープにフリーズ動作実行用スイッチを設けるのがよい。静止画像記録手段は、静止画像を記録するため、動画像表示における画像信号読出し時間間隔に相当する上記所定時間間隔よりも短い時間に対応した電子シャッタ速度による電子シャッタ動作によって、撮像素子から被写体に応じた画像信号を読み出して処理する。プロセッサにビデオレコーダなどの記録装置が接続され、オペレータのスイッチ操作に従い、静止画像がプロセッサ内のメモリおよび記録装置へ記録される。静止画像記録時の露光時間に対応する電子シャッタ速度は、動画像表示における読出し時間間隔やビデオスコープ先端と観察被写体との距離等を考慮して定めればよい。
【０００９】
本発明の静止画像記録手段は、暫定静止画像表示手段と、光量増加手段と、待機手段と、記録実行手段とを有することを特徴とする。オペレータによって記録実行操作部材が操作されると、暫定静止画像表示手段は、モニタに静止画像を暫定的に表示させるため、前記記録実行操作部材が操作された直後に静止画像表示動作を実行させる。例えば、プロセッサ内のメモリに一時的に静止画像に応じた画像信号を格納させ、メモリの書き換え処理を実行させないことによって静止画像をモニタに表示させる。光量増加手段は、被写体への光量が静止画像の記録に対応する基準光量に達するように光量調整手段を制御する。ここで、基準光量は、所望する静止画像の明るさが得られる時に必要な光量を示し、設定された電子シャッタ速度又は／および所定時間間隔に基づいて定められる。記録された静止画像から医師が正確に診断できるように、静止画像の明るさと動画像の明るさが実質的に等しくなるようにするのが望ましい。この場合、基準光量は、電子シャッタ速度に対応した時間と所定時間間隔との比に基づいて定められる。例えば、所定時間間隔が１／６０秒で電子シャッタ速度が１／１２０秒である場合、基準光量は、フリーズ動作実行直前において被写体へ照射される光量の２倍の光量に定められる。光量調整手段が絞りである場合、光量増加手段は、基準光量に達するまで現在の開度より絞りを所定量だけさらに開ける。このとき、迅速かつ適切に光量が基準光量に達するように、絞りを徐々に開けていくのが望ましい。
【００１０】
被写体への光量が基準光量に達するまでの間、待機手段は、静止画像記録動作の実行を待機させる。そして、記録実行手段は、被写体への光量が基準光量に達した場合、静止画像記録動作を実行させて静止画像を記録する。例えば、画像記録手段は、プロセッサ内に設けたメモリに静止画像の画像信号を格納し、メモリからビデオレコーダなどの記録装置へ画像信号を送る。記録実行手段は、基準光量に達すると同時に静止画像を記録してもよく、あるいは遅延時間（Delay Time）を設けて静止画像を記録してもよい。
【００１１】
被写体への光量が基準光量に達する時点を見計らって記録動作が実行されるため、像ブレがない静止画像を一度で得ることができる。また、光量調整手段の構成に応じて電子シャッタ速度を設定することが可能であり、画像信号の読出し時間間隔（所定時間間隔）および電子シャッタ速度に従って基準光量を適宜設定することが可能である。そのため、フリーズ動作時における光量増加の程度が適正に設定されることにより、適切な明るさの静止画像を常に得ることができる。特に、光量調整手段が絞りの場合、絞りの開度と光量増加量（変化量）の特性を考慮しながら電子シャッタ速度および基準光量を定めればよい。
【００１２】
さらに、記録実行操作部材が操作されてから実際に静止画像が記録されるまでの間、暫定的に静止画像がモニタに表示される。そのため、光量が基準光量に達するまでの過程において、明るさ変化の著しい被写体像はモニタに表示されない。このように暫定的に静止画像を表示することにより、フリーズ動作時にオペレータに不快感を与えず、また、フリーズ動作時に被写体像の急激な明るさ変化によって操作ミスを起こすことを防ぎ、観察、処置等に影響を与えなくて済む。
【００１３】
簡易な構成によって基準光量に達しているか否かを判断するため、待機手段は、輝度値に基づいて被写体への光量が基準光量に達しているか否かを判断する光量判別手段を有することが望ましい。この場合、被写体への光量は、撮像素子の露光量として検出される。輝度値は、動画像表示と同様に、撮像素子から順次一定の時間間隔で画像信号を読出し、読み出した画像信号に基づいて算出すればよい。自動調光処理待機手段が実行されている場合、待機手段は、算出される輝度値が基準光量に応じた静止画像基準輝度値に達しているか否かを判別する輝度値判別手段を有するのが好ましい。
【００１４】
フリーズ動作を実行開始してから実際に静止画像を記録するまでの間、例えば待機手段は、被写体への光量が基準光量に達するまで電子シャッタ動作および静止画像記録動作を実行させず、被写体への光量が基準光量に達した場合に記録実行手段が電子シャッタ動作および静止画像記録動作を実行させることが望ましい。例えば、待機手段が輝度値に基づいて基準光量に達しているか否かを判断し、所定時間間隔と電子シャッタ速度との比が２倍である場合、静止画像基準輝度値は動画像基準輝度値の２倍の値となる。
【００１５】
あるいは、待機手段は、伝シャッタ動作を実行させる一方で静止画像記録動作を実行させず、被写体への光量が基準光量に達した場合、記録実行手段が静止画像記録動作を実行させるようにしてもよい。この場合、待機手段が輝度値に基づいて基準光量に達しているか否かを判断し、所定時間間隔と電子シャッタ速度との比が２倍である場合、静止画像基準輝度値は動画像基準輝度値と等しい。
【００１６】
本発明の電子内視鏡装置のプロセッサは、静止画像の記録を実行するための記録実行操作部材および撮像素子を有するビデオスコープと、ビデオスコープおよび表示用モニタが接続される電子内視鏡装置のプロセッサであって、被写体の動画像をモニタへ表示するため、被写体に応じた画像信号を撮像素子から所定時間間隔毎に読み出して処理する動画像表示手段と、被写体を照明するため光源から放射される光の光量を調整する光量調整手段と、被写体の静止画像を記録するため、操作部材に対する操作に従い、所定時間間隔よりも短い時間に対応した電子シャッタ速度による電子シャッタ動作によって撮像素子から被写体に応じた画像信号を読み出して処理する静止画像記録手段とを備え、静止画像記録手段は、モニタに静止画像を暫定的に表示させるため、記録実行操作部材が操作された直後に静止画像表示動作を実行させる暫定静止画像表示手段と、被写体への光量が静止画像の記録に対応する基準光量に達するように光量調整手段を制御する光量増加手段と、被写体への光量が基準光量に達するまで静止画像記録動作の実行を待機させる待機手段と、被写体への光量が基準光量に達した場合、静止画像記録動作を実行させて静止画像を記録する記録実行手段とを有することを特徴とする電子内視鏡装置のプロセッサ。
【００１７】
本発明の電子内視鏡装置用静止画像記録装置は、撮像素子を有するビデオスコープと、ビデオスコープおよび表示用モニタが接続されるプロセッサとを備えた電子内視鏡装置であって、被写体の動画像をモニタへ表示するため、被写体に応じた画像信号を撮像素子から所定時間間隔毎に読み出して処理する動画像表示手段と、被写体を照明するため光源から放射される光の光量を調整する光量調整手段と、静止画像の記録を実行するための記録実行操作部材とを備えた電子内視鏡装置用静止画像記録装置において、被写体の静止画像を記録するため、操作部材に対する操作に従い、所定時間間隔よりも短い時間に対応した電子シャッタ速度による電子シャッタ動作によって撮像素子から被写体に応じた画像信号を読み出して処理する静止画像記録手段とを備え、静止画像記録手段が、モニタに静止画像を暫定的に表示させるため、記録実行操作部材が操作された直後に静止画像表示動作を実行させる暫定静止画像表示手段と、被写体への光量が静止画像の記録に対応する基準光量に達するように光量調整手段を制御する光量増加手段と、被写体への光量が基準光量に達するまで静止画像記録動作の実行を待機させる待機手段と、被写体への光量が基準光量に達した場合、静止画像記録動作を実行させて静止画像を記録する記録実行手段とを有することを特徴とする。
【００１８】
本発明のプログラムは、撮像素子を有するビデオスコープと、ビデオスコープおよび表示用モニタが接続されるプロセッサとを備えた電子内視鏡装置であって、被写体の動画像をモニタへ表示するため、被写体に応じた画像信号を撮像素子から所定時間間隔毎に読み出して処理する動画像表示手段と、被写体を照明するため光源から放射される光の光量を調整する光量調整手段と、静止画像の記録を実行するための記録実行操作部材と、被写体の静止画像を記録するため、操作部材に対する操作に従い、所定時間間隔よりも短い時間に対応した電子シャッタ速度による電子シャッタ動作によって撮像素子から被写体に応じた画像信号を読み出して処理する静止画像記録手段とを備えた電子内視鏡装置において静止画像記録処理を実行するためのプログラムであって、モニタに静止画像を暫定的に表示させるため、記録実行操作部材が操作された直後に静止画像表示動作を実行させる暫定静止画像表示手段と、被写体への光量が静止画像の記録に対応する基準光量に達するように光量調整手段を制御する光量増加手段と、被写体への光量が基準光量に達するまで静止画像記録動作の実行を待機させる待機手段と、被写体への光量が基準光量に達した場合、静止画像記録動作を実行させて静止画像を記録する記録実行手段とを機能させることを特徴とする。
【００１９】
【発明の実施の形態】
以下では、図面を参照して本発明の実施形態である電子内視鏡装置について説明する。
【００２０】
図１は、第１の実施形態である電子内視鏡装置のブロック図である。
【００２１】
電子内視鏡装置では、撮像素子であるＣＣＤ５４を有するビデオスコープ５０と、ＣＣＤ５４から読み出される画像信号を処理するプロセッサ１０とが備えられており、観察部位の画像を動画像あるいは静止画像として表示するモニタ６０がプロセッサ１０に接続される。ビデオスコープ５０はプロセッサ１０に着脱自在に接続可能であり、また、プロセッサ１０にはビデオレコーダ７０、ビデオプリンタ８０が接続されている。
【００２２】
ランプ点灯スイッチ（図示せず）がＯＮになると、ランプ電源３６から光源ランプ３４へ電力が供給されて点灯する。点灯した光源ランプ３４から放射された光は、集光レンズ（図示せず）および絞り３３を介してビデオスコープ５０内に設けられた光ファイバー束５６の入射端に入射する。光ファイバー束５６は、光源ランプ３４から放射される光を観察部位Ｓのあるビデオスコープ５０の先端側へ伝達する光ファイバーであり、光ファイバー束５６を通った光は出射端５６Ｂから出射する。出射端５６Ｂから出射した光は拡散レンズである配光レンズ（図示せず）を介して観察部位Ｓに照射される。
【００２３】
観察部位Ｓにおいて反射した光は、対物レンズ（図示せず）を通ってＣＣＤ（Charge-Coupled Device ）５４の受光面に到達し、これにより観察部位Ｓの被写体像がＣＣＤ５４の受光面に形成される。本実施形態では、カラー撮像方式として単板同時式が適用されており、ＣＣＤ５４の受光面上にはイエロー（Ｙｅ）、シアン（Ｃｙ）、マゼンタ（Ｍｇ）、グリーン（Ｇ）の色要素が市松状に並べられた補色カラーフィルタ（図示せず）が受光面の各画素に対応するよう配置されている。ＣＣＤ５４では、補色カラーフィルタを通る色に応じた被写体像のアナログ画像信号が光電変換により発生し、所定時間間隔ごとに１フィールド（１フレーム分）の画像信号が、色差線順次方式に従って順次読み出される。カラーテレビジョン方式としては例えばＮＴＳＣ方式が適用されており、１／６０秒間隔（１／３０秒間隔）ごとに１フィールド分（１フレーム分）の画像信号が動画表示のために順次読み出され、信号線ＩＣを経由してプロセッサ１０へ送られる。ＣＣＤ５４はＣＣＤ駆動回路５２によって駆動されており、ＣＣＤ駆動回路５２から画像信号を読み出すためのパルス信号が出力される。
【００２４】
プロセッサ１０に入力された画像信号は、不図示の前段回路にて増幅処理された後、Ａ／Ｄ変換器２２に送られる。Ａ／Ｄ変換器２２では、アナログの画像信号がデジタルの画像信号に変換され、デジタル画像信号が信号処理回路２４へ送られる。信号処理回路２４では、デジタル画像信号に対して、Ｒ，Ｇ，Ｂゲイン処理、ガンマ補正など様々な信号処理が施されるとともに、画像信号に基づいて輝度信号が生成される。１フレーム分のデジタル画像信号が順次フィールドメモリであるメモリ２６に格納される一方、輝度信号はＣＰＵ（Central Processing Unit）を含むシステムコントロール回路３０へ順次送られる。メモリ２６からデジタル画像信号が読み出されると、デジタル画像信号はＤ／Ａ変換器２８においてアナログ画像信号に変換される。アナログ画像信号は、不図示の後段回路にて所定の信号処理が施されてＮＴＳＣコンポジット信号、Ｙ／Ｃ分離信号（Ｓビデオ信号）、ＲＧＢ分離信号などのビデオ信号としてモニタ６０へ出力され、これにより被写体像が動画像としてモニタ６０に映し出される。
【００２５】
システムコントロール回路３０はプロセッサ１０全体を制御し、信号処理回路２４、絞り制御回路３２、ＣＣＤ駆動回路５２などの各回路に制御信号を出力する。システムコントロール回路３０内のＲＯＭ（図示せず）には、フリーズ動作時における静止画像記録処理を実行するとともにプロセッサ全体の動作を制御するためのプログラムが格納されている。タイミングコントロール回路（図示せず）では、信号の処理タイミングを調整するクロックパルスがプロセッサ１０内の各回路へ向けて出力される。
【００２６】
ライトガイド５６の入射端と集光レンズとの間には、被写体Ｓに照射される光の光量を調整するための絞り３３が設けられており、絞り制御回路３２の制御によって開閉する。信号処理回路２４からシステムコントロール回路３０へ送られる輝度信号に基づき、制御信号がシステムコントロール回路３０から絞り制御回路３２へ出力される。絞り制御回路３２は制御信号に基づいてモータ（図示せず）を駆動させ、これによりモータと接続された絞り３３が開閉する。
【００２７】
ビデオスコープ５０にはフリーズスイッチボタン５８が設けられており、オペレータによってフリーズスイッチボタン５８が押下されると、押下操作により生じた操作信号がプロセッサ１０のシステムコントロール回路３０へ送られる。そして、検出された操作信号に基づいて、フリーズ動作が実行される。すなわち、所定の電子シャッタ速度による電子シャッタ動作によって画像信号がＣＣＤ５４から読み出され、Ａ／Ｄ変換器２２、信号処理回路２４等において処理される。処理された１フレーム分の画像信号は、静止画像記録のためメモリ２６に記憶される。
【００２８】
メモリ２６に格納された１フレーム分の画像信号は、画像記録用メモリ７５に記録されるととともに、ビデオレコーダ７０、ビデオプリンタ８０へ映像信号として送信される。ビデオレコーダ７０は静止画像を記録するための記録装置であり、ビデオプリンタ８０では、フリーズ動作時に送られてきたビデオ信号に基づいて静止画像が印刷される。静止画像の記録が実行されている間、メモリ２６に格納された画像信号は更新されず、新たな書き込み処理は実行されない。これにより、モニタ６０には静止画像が表示される。また、後述するように、フリーズスイッチボタン５８が押下されてから実際に静止画像が記録されるまでの間、暫定的に静止画像が表示される。オペレータがフリーズスイッチボタン５８を指から離すと、フリーズ動作が終了し、再び動画像を表示する通常観察モードに移る。
【００２９】
図２は、本実施形態におけるプロセッサ１０の動作処理を示したフローチャートである。なお、このフローチャートはプロセッサ１０の主電源がＯＮになると、実行開始される。
【００３０】
ステップＳ１０１では、絞り３３や、信号処理におけるゲイン係数などが初期値に設定され、フリーズ動作時の電子シャッタ速度もあらかじめ定められた値に設定される。ステップＳ１０２では、通常観察、すなわち動画像をモニタ６０に表示するための処理が施される。なお、通常観察モードでは、表示される被写体像の明るさが一定となるように自動調光処理が実行されており、ここでは１／６０秒間隔ごとの割り込み演算処理が実行される。ステップＳ１０２が実行されると、ステップＳ１０３へ進む。
【００３１】
ステップＳ１０３では、ビデオスコープ５０のフリーズスイッチボタン５８がオペレータによって押下されたか否かが判断される。フリーズスイッチボタン５８が押下されていないと判断された場合、ステップＳ１０２へ戻る。一方、フリーズスイッチボタン５８が押下されたと判断された場合、ステップＳ１０４へ進む。ステップＳ１０４では、フリーズ動作処理が実行され、静止画像がビデオレコーダ７０などへ出力されるとともに、モニタ６０に表示される。
【００３２】
図３は、図２のステップＳ１０４におけるフリーズ動作処理のサブルーチンを示した図であり、図４は、フリーズ動作時における輝度信号のレベルを時系列的に示した図である。
【００３３】
本実施形態では、静止画像を記録する場合、被写体像について通常観察時の明るさとフリーズ動作時の明るさが同一となるように光量調整が施される。即ち、被写体像についてフリーズ動作した時のＣＣＤ５４の各画素における電荷蓄積量を、同じ被写体像について通常観察した時のＣＣＤ５４の対応する各画素における電荷蓄積量と同一となるように光量調整する。通常観察時において画像信号が１／６０秒間隔でＣＣＤ５４から読み出されていることから、静止画像記録時の電子シャッタ速度は１／１２０秒に定められている。ただし、電子シャッタ速度は、静止画像記録時におけるＣＣＤ５４の露光時間に相当する。電子シャッタ速度が動画像表示の信号読み出し時間間隔（＝１／６０秒）の２倍のシャッタ速度である（露光時間が半分である）ことから、フリーズ動作時において被写体に照射すべき光量、すなわちＣＣＤ５４の受光面に入射すべき光量は、通常観察時の光量の２倍となる。
【００３４】
図４では、システムコントロール回路３０が検出する輝度信号のレベルが時系列的に示されており、また、絞り３３を通過する光の光量（以下では、通過光量という）が輝度信号レベルによって表されている。通常観察時においては、画像信号から検出される輝度信号レベル、すなわち輝度値Ｙが被写体像の適切な明るさ基準を示す輝度値Ｙ１（以下では、動画像基準輝度値という）で維持されるように自動調光処理が施されている。ただし、輝度値は、被写体像の明るさを２５６段階で分類したときに、０〜２５５の間のいずれかの整数値として定められる。また、輝度値はここでは輝度平均値を示しており、０〜２５５の各輝度値における画素の数とその輝度値との乗数の総和を１フィールド分の画素数で割ることによって算出される。
【００３５】
本実施形態では、１／６０秒間隔毎に検出される輝度値Ｙを判断基準にして、被写体への光量が２倍の光量（基準光量）に達しているか否かが判断される。すなわち、輝度値Ｙが動画像基準輝度値Ｙ１の２倍である輝度値Ｙ２（以下では、静止画像基準輝度値という）に達しているか否かが判断される。
【００３６】
ステップＳ２０１では、通常観察時に所定開度まで開いていた絞り３３がさらに開くように、絞り制御回路３２へ制御信号が出力される。この時、絞り３３は徐々に開くように制御される。そしてステップＳ２０２では、暫定表示動作が実行される。すなわち、暫定的に静止画像をモニタ６０に表示するため、静止画像表示用の１フレーム分の画像信号がメモリ２６に格納される。このとき、電子シャッタ速度が１／６０秒による電子シャッタ動作が実行される。メモリ２６に暫定静止画像表示用の画像信号が格納されると、後述する記録動作が実行されるまで、メモリ２６の書き換え処理は行われない。その結果、暫定的表示用の静止画像がモニタ６０に表示される。ステップＳ２０１で絞り３３がさらに開くように制御信号が出力されてからステップＳ２０２で静止画像表示用の１フレーム分の画像信号がメモリ２６に格納されるまでの間は、絞り３３は徐々に開くように制御されるので、表示される暫定的表示用の静止画像の明るさは通常観察時の動画像の明るさとほとんど変わることがない。なお、暫定静止画像を表示している間、輝度値Ｙを算出するため、１／６０秒間隔でＣＣＤ５４から画像信号は読み出される。ステップＳ２０３では、ＣＣＤ５４から読み出される１フィールド分の画像信号から生成される輝度信号に基づいて、輝輝度値Ｙが順次算出される。ステップＳ２０３が実行されると、ステップＳ２０４へ進む。
【００３７】
ステップＳ２０４では、算出された輝度値Ｙが静止画像基準輝度値Ｙ２と等しいか否かが判断される。輝度値Ｙが静止画像基準輝度値Ｙ２と等しくないと判断されると、ステップＳ２０３へ戻り、輝度値Ｙが静止画像基準輝度値Ｙ２と等しくなるまで繰り返しステップＳ２０３、Ｓ２０４が実行される。一方、輝度値Ｙが静止画像基準輝度値Ｙ２と等しいと判断された場合、ステップＳ２０５へ進み、絞り３３を開ける開放動作を停止するように制御信号が絞り制御回路３２へ出力される。ステップＳ２０５が実行されると、ステップＳ２０６へ進む。
【００３８】
ステップＳ２０６では、絞り３３の開放動作を停止するように制御信号が出力されてから絞り３３が実際に停止する間までの時間を考慮した遅延時間ＴＲ経過後、電子シャッタ速度１／１２０秒で電子シャッタ動作が実行されるようにＣＣＤ駆動回路５２へ制御信号が送られる。ＣＣＤ駆動回路５２は、システムコントロール回路３０からの制御信号に基づき、露光時間が１／１２０秒となるように電荷掃き出しパルス信号をＣＣＤ５４へ出力する。そして、ステップＳ２０７では、電子シャッタ速度１／１２０秒で撮像された１フレーム分の静止画像に応じた画像信号がメモリ２６へ格納され、画像記録用メモリ７５、ビデオレコーダ７０へ静止画像が出力される。それとともに、ステップＳ２０２の実行により表示されていた暫定的表示用の静止画像がステップＳ２０７で更新され、電子シャッタ速度１／１２０秒で撮像されて実際に記録される静止画像がモニタ６０へ表示される。静止画像を記録している間、電子シャッタ速度、すなわち露光時間が通常観察時の露光時間の半分であるため、画像信号の輝度値Ｙは通常観察時の輝度値Ｙ１と略等しい。また、フリーズスイッチボタン５８がＯＦＦ状態になるまで、メモリ２６に格納された１フレーム分の画像信号は書き換えられない。ステップＳ２０７が実行されると、このサブルーチンは終了し、図２のステップＳ１０５へ移る。
【００３９】
ステップＳ１０５では、オペレータがフリーズスイッチボタン５８から指を離すことによってフリーズスイッチボタン５８がＯＦＦ状態になっているか否かが判断される。フリーズスイッチボタン５８がＯＦＦ状態ではないと判断された場合、ステップＳ１０４へ戻る。一方、フリーズスイッチボタン５８がＯＦＦ状態になっていると判断された場合、ステップＳ１０６へ進み、フリーズ動作処理が解除され、ステップＳ１０３へ戻る。主電源がＯＦＦになるまで、ステップＳ１０２〜Ｓ１０６が繰り返し実行される。
【００４０】
以上のように本実施形態によれば、フリーズスイッチボタン５８がオペレータによって操作されると、被写体への光量が通常観察時の２倍となるように絞り３３が開く。そして、被写体への光量に応じた輝度値Ｙが静止画像基準輝度値Ｙ２に達するまで、電子シャッタ動作は実行されない。輝度値Ｙが静止画像基準輝度値Ｙ２に達すると電子シャッタ動作が実行され、通常観察時における画像信号読み出し時間間隔（＝１／６０秒）の２倍の電子シャッタ速度（＝１／１２０秒）で画像信号が読み出され、静止画像が画像記録用メモリ７５、ビデオレコーダ７０に記録される。
【００４１】
また、本実施形態では、フリーズスイッチボタン５８が操作されると同時に、暫定的に静止画像表示用の画像信号がメモリ２６に格納される。そして、実際に記録される静止画像を表示するまでの間、暫定的静止画像がモニタ６０に表示される。従って、絞り３３の開放動作に伴ってモニタ上の画像の明るさが急激に増すことがない。
【００４２】
本実施形態では、通常観察時の明るさと記録静止画像の明るさが一致するように電子シャッタ速度が１／１２０秒に定められているが、通常観察時の画像信号読み出し時間間隔に応じてビデオスコープの手ぶれや観察部位自体の動き等による画質低下が目立たないよう電子シャッタ速度を定めればよい。例えば、カラーテレビジョン方式として読み出し時間間隔が１／５０秒であるＰＡＬ方式が適用される場合、電子シャッタ速度は１／１００秒に定めてもよい。
【００４３】
静止画像の明るさがオペレータの所望する明るさとなるように電子シャッタ速度を設定してもよい。この場合、静止画像基準輝度値Ｙ２は、設定されたシャッタ速度に従って所定値に定められる。また、電子シャッタ速度に関しては、オペレータによる操作によって設定変更できる構成にしてもよい。輝度値Ｙおよび基準輝度値Ｙ１、Ｙ２は、輝度平均値以外の代表的な値を適用してもよい。
【００４４】
本実施形態では、光量調整に絞り３３が適用されているが、その他の構成によって光量調整を行ってもよい。例えば、液晶板や偏光板を適用させ、電圧制御によって光量調整してもよい。あるいは、光源として発光ダイオードを適用し、発光ダイオードの発光量を制御して光量調整を行ってもよい。この場合、輝度値Ｙが静止画像基準輝度値Ｙ２に達した時点で、遅延時間ＴＲを設けることなくすぐに電子シャッタ動作を実行して画像記録動作を行うことが可能となる。
【００４５】
次に、図５、図６を用いて、第２の実施形態について説明する。第２の実施形態では、第１の実施形態と異なり、絞り３３の開放動作と同時に電子シャッタ動作が実行される。その他の構成に関しては、実質的に第１の実施形態と同じである。
【００４６】
図５は、第２の実施形態における図２のステップＳ１０４のサブルーチンを示しており、図６は、第２の実施形態における輝度信号レベルを時系列的に示した図である。フリーズスイッチボタン５８が操作されると、フリーズ動作処理が実行開始される。
【００４７】
ステップＳ３０１では、フリーズスイッチボタン５８に対する操作に従い、絞り３３が開くように制御信号が絞り制御回路３２へ出力される。そして、ステップＳ３０２では、絞り３３の開放動作と同時に電子シャッタ動作が実行される。ステップＳ３０３では、静止画像を暫定的にモニタ６０へ表示するため、１フレーム分の静止画像に応じた画像信号がメモリ２６に格納され、メモリ２６に格納された画像信号がモニタ６０へ出力される。記録動作が実行されるまでの間、メモリ２６の書き換え処理は行われない。
【００４８】
ステップＳ３０４では、読み出される画像信号に基づいて輝度値Ｙが算出される。図６に示すように、電子シャッタ動作が絞り３３の開放と同時に実行されるため、検出される輝度値Ｙは瞬間的に通常観察時の輝度値Ｙ１の半分になり、絞り３３が徐々に開くに従って検出される輝度値Ｙも徐々に大きくなっていく。第２の実施形態では、動画像基準輝度値Ｙ１と静止画像基準輝度値Ｙ２は等しい。
【００４９】
ステップＳ３０５では、輝度値Ｙが静止画像基準輝度値Ｙ２と等しいか否かが判断される。輝度値Ｙが基準輝度値Ｙ１と等しくないと判断された場合、ステップＳ３０４へ戻る。一方、輝度値Ｙが静止画像基準輝度値Ｙ２と等しいと判断された場合、ステップＳ３０６へ進み、絞り３３の開放動作が停止される（図６参照）。そして、ステップＳ３０７では、静止画像記録動作が実行され、電子シャッタ動作により得られた画像信号がメモリ２６に格納され、画像記録用メモリ７５、ビデオレコーダ７０へ静止画像が記録される。それとともに、ステップＳ３０３の実行により表示されていた暫定的表示用の静止画像がステップＳ３０７で更新され、実際に記録される静止画像がモニタ６０へ表示される。ステップＳ３０７が実行されると、このサブルーチンは終了する。
【００５０】
このように第２の実施形態によれば、フリーズスイッチボタン５８が操作されると、絞り３３が徐々に開くと同時に電子シャッタ動作が実行される。そして、検出される輝度値Ｙが静止画像基準輝度値Ｙ２と等しくなった場合、静止画像記録動作が実行され、静止画像が記録される。
【００５１】
【発明の効果】
このように本発明によれば、フリーズ動作を繰り返し実行することなく、適切な明るさの静止画像を得ることができるとともに、フリーズ動作の最中において被写体観察に支障のない画像をモニタに表示することができる。
【図面の簡単な説明】
【図１】第１の実施形態である電子内視鏡装置のブロック図である。
【図２】プロセッサのメイン動作処理を示したフローチャートである。
【図３】図２のステップＳ１０４におけるフリーズ動作処理のサブルーチンを示した図である。
【図４】フリーズ動作時における輝度信号のレベルを時系列的に示した図である。
【図５】第２の実施形態におけるフリーズ動作処理のサブルーチンを示した図である。
【図６】第２の実施形態におけるフリーズ動作時における輝度信号のレベルを時系列的に示した図である。
【符号の説明】
１０プロセッサ
２４信号処理回路
２６メモリ
３０システムコントロール回路
３２絞り制御回路
３３絞り（光量調整手段）
５０ビデオスコープ
５２ＣＣＤ駆動回路
５４ＣＣＤ（撮像素子）
５８フリーズスイッチボタン
６０モニタ
７０ビデオレコーダ
７５画像記録用メモリ
Ｙ輝度値
Ｙ１動画像基準輝度値
Ｙ２静止画像基準輝度値[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic endoscope apparatus that includes a video scope (electronic scope) having an image sensor and a processor that performs signal processing on an image signal read from the image sensor, and in particular, records a still image. Related to freeze operation.
[0002]
[Prior art]
In a conventional electronic endoscope apparatus, a moving image is displayed on a monitor, and a freeze operation can be executed according to an operator's operation. That is, a still image recording process is executed, and the still image is recorded in a recording device such as a memory or a video recorder.
[0003]
When a still image is recorded in an electronic endoscope apparatus, the recorded still image may have a resolution, a color shift, or the like due to a camera shake of the videoscope or a movement of the observation site itself, and there is a possibility that the image quality may deteriorate. In particular, when the distance between the observation site and the distal end of the video scope is large, or when zoom shooting is performed using an image enlargement function, image quality degradation is significant. In order to solve such a problem, a configuration is known in which the amount of light applied to the subject is increased and the shutter speed of the electronic shutter is set to a high speed during execution of the freeze operation (Japanese Patent Application Laid-Open No. 6-296580 and Japanese Patent Application Laid-Open 11-244229 and JP-A-2001-100111). In this case, the light amount is increased by the full aperture operation or the strobe light emission, and the shutter speed is set according to the increase in the light amount.
[0004]
[Problems to be solved by the invention]
In the above configuration, the amount of light to be increased is determined in advance, and in order to record a still image with an appropriate brightness, it is necessary to adjust the shutter speed while judging the luminance level of the still images recorded sequentially. . In addition, if the aperture of the diaphragm just before the freeze operation is small, the amount of light to the subject increases momentarily and excessively due to the full aperture operation, and it is difficult to obtain a still image with appropriate brightness.
[0005]
Therefore, in the present invention, it is possible to obtain a still image with appropriate brightness without repeatedly performing the freeze operation, and to display an image on the monitor that does not interfere with subject observation during the freeze operation. An object is to obtain an endoscope apparatus and an endoscope still image recording apparatus.
[0006]
[Means for Solving the Problems]
An electronic endoscope apparatus according to the present invention is an electronic endoscope apparatus that includes a video scope having an image sensor and a processor to which the video scope and a display monitor are connected, and displays a subject image on the processor. A monitor is connected. In order to display a moving image of a subject, the electronic endoscope apparatus includes a moving image display unit that reads and processes an image signal corresponding to the subject from the image sensor at predetermined time intervals. For example, when the NTSC system is applied as a color television system, image signals may be read at 1/60 second intervals for moving image display. In addition, the electronic endoscope apparatus includes a light amount adjusting unit that adjusts the amount of light emitted from the light source to illuminate the subject. For example, the light amount adjusting means is a diaphragm, and the diaphragm is disposed so as to be interposed between the light source and a light transmission member such as a light guide. Further, a liquid crystal plate (liquid crystal shutter) or a polarizing plate may be disposed instead of the diaphragm. Alternatively, a light emission control control circuit may be provided as the light amount adjusting means so as to control the light emission amount of light emitted from the light source.
[0007]
In order to make the brightness of the moving image displayed on the monitor appropriate, the electronic endoscope apparatus includes an automatic light control processing unit that controls the light amount adjusting unit so that the brightness of the displayed moving image is the same. It is good. For example, when the light intensity adjusting means is a diaphragm, a luminance value is calculated based on image signals sequentially read from the image sensor, and based on the luminance value and a moving image reference luminance value indicating appropriate brightness of the subject image. What is necessary is just to open and close an aperture. The luminance value is a luminance level value indicating the typical brightness of the subject image. For example, when the brightness is divided into 1 to 256 levels, the luminance value is represented by an integer value of 0 to 255. As the luminance value, for example, an average luminance value indicating the average luminance of the entire subject image is applied. In this case, the moving image reference luminance value may be set to any value from 120 to 140, for example.
[0008]
The electronic endoscope apparatus includes a recording execution operation member operated by an operator and a still image recording unit in order to execute a freeze operation. For example, the video scope may be provided with a freeze operation execution switch. The still image recording means records the still image from the image sensor to the subject by an electronic shutter operation at an electronic shutter speed corresponding to a time shorter than the predetermined time interval corresponding to the image signal readout time interval in moving image display. The corresponding image signal is read and processed. A recording device such as a video recorder is connected to the processor, and a still image is recorded in a memory and a recording device in the processor according to an operator's switch operation. The electronic shutter speed corresponding to the exposure time at the time of still image recording may be determined in consideration of the readout time interval in moving image display, the distance between the videoscope tip and the observation subject, and the like.
[0009]
The still image recording means of the present invention is characterized by having provisional still image display means, light quantity increasing means, standby means, and recording execution means. When the recording execution operation member is operated by the operator, the temporary still image display means executes a still image display operation immediately after the recording execution operation member is operated in order to temporarily display a still image on the monitor. For example, the image signal corresponding to the still image is temporarily stored in the memory in the processor, and the still image is displayed on the monitor by not executing the memory rewriting process. The light amount increasing unit controls the light amount adjusting unit so that the light amount to the subject reaches a reference light amount corresponding to recording of a still image. Here, the reference light amount indicates a light amount required when a desired still image brightness is obtained, and is determined based on a set electronic shutter speed or / and a predetermined time interval. It is desirable that the brightness of the still image and the brightness of the moving image be substantially equal so that the doctor can accurately diagnose from the recorded still image. In this case, the reference light amount is determined based on a ratio between a time corresponding to the electronic shutter speed and a predetermined time interval. For example, when the predetermined time interval is 1/60 seconds and the electronic shutter speed is 1/120 seconds, the reference light amount is set to a light amount that is twice the light amount irradiated to the subject immediately before the freeze operation is performed. When the light quantity adjusting means is a diaphragm, the light quantity increasing means further opens the diaphragm by a predetermined amount from the current opening until the reference light quantity is reached. At this time, it is desirable to gradually open the diaphragm so that the light amount reaches the reference light amount quickly and appropriately.
[0010]
The standby unit waits for the execution of the still image recording operation until the light amount to the subject reaches the reference light amount. Then, the recording execution unit records the still image by executing the still image recording operation when the light amount to the subject reaches the reference light amount. For example, the image recording means stores an image signal of a still image in a memory provided in the processor, and sends the image signal from the memory to a recording device such as a video recorder. The recording execution means may record a still image as soon as the reference light amount is reached, or may record a still image with a delay time (Delay Time).
[0011]
Since the recording operation is executed at the time when the light amount to the subject reaches the reference light amount, a still image without image blur can be obtained at a time. Also, the electronic shutter speed can be set according to the configuration of the light amount adjusting means, and the reference light amount can be appropriately set according to the image signal readout time interval (predetermined time interval) and the electronic shutter speed. Therefore, it is possible to always obtain a still image with appropriate brightness by appropriately setting the degree of increase in the amount of light during the freeze operation. In particular, when the light amount adjusting means is a diaphragm, the electronic shutter speed and the reference light amount may be determined in consideration of the characteristics of the aperture of the diaphragm and the light amount increase (change amount).
[0012]
Further, the still image is temporarily displayed on the monitor from when the recording execution operation member is operated until the still image is actually recorded. Therefore, in the process until the light amount reaches the reference light amount, a subject image whose brightness changes significantly is not displayed on the monitor. By temporarily displaying still images in this way, there is no discomfort to the operator during the freeze operation, and it is possible to prevent erroneous operation due to a sudden change in the brightness of the subject image during the freeze operation. And so on.
[0013]
In order to determine whether or not the reference light amount has been reached with a simple configuration, it is preferable that the standby unit has a light amount determination unit that determines whether or not the light amount to the subject has reached the reference light amount based on the luminance value. . In this case, the amount of light to the subject is detected as the exposure amount of the image sensor. Similar to the moving image display, the luminance value may be calculated based on the read image signal by sequentially reading the image signal from the image sensor at a constant time interval. When the automatic dimming process standby unit is executed, the standby unit includes a luminance value determination unit that determines whether or not the calculated luminance value has reached the still image reference luminance value corresponding to the reference light amount. preferable.
[0014]
For example, the standby unit does not execute the electronic shutter operation and the still image recording operation until the light amount to the subject reaches the reference light amount until the still image is actually recorded after the start of the freeze operation. It is desirable that the recording execution means execute the electronic shutter operation and the still image recording operation when the light amount reaches the reference light amount. For example, when the standby unit determines whether or not the reference light amount has been reached based on the luminance value, and the ratio between the predetermined time interval and the electronic shutter speed is twice, the still image reference luminance value is the moving image reference luminance value. Is twice the value.
[0015]
Alternatively, the waiting unit may execute the still image recording operation when the light amount to the subject reaches the reference light amount without executing the still image recording operation while executing the transmission shutter operation. Good. In this case, the standby unit determines whether or not the reference light amount has been reached based on the luminance value, and when the ratio between the predetermined time interval and the electronic shutter speed is twice, the still image reference luminance value is the moving image reference luminance. Equal to value.
[0016]
A processor of an electronic endoscope apparatus according to the present invention includes a video scope having a recording execution operation member and an image sensor for executing recording of a still image, and an electronic endoscope apparatus to which the video scope and a display monitor are connected. A processor for displaying a moving image of a subject on a monitor, moving image display means for reading and processing an image signal corresponding to the subject at predetermined time intervals from an image sensor, and radiation from a light source for illuminating the subject; In order to record a still image of the subject, and a light amount adjusting means for adjusting the amount of light to be recorded, the image pickup device is moved from the image sensor to the subject by an electronic shutter operation at an electronic shutter speed corresponding to a time shorter than a predetermined time interval according to an operation on the operation member. A still image recording unit that reads and processes the corresponding image signal, and the still image recording unit provisionally transmits the still image to the monitor. A temporary still image display means for executing a still image display operation immediately after the recording execution operation member is operated, and a light amount adjusting means so that the light amount to the subject reaches a reference light amount corresponding to recording of the still image A light amount increasing means for controlling the light amount, a standby means for waiting for execution of the still image recording operation until the light amount to the subject reaches the reference light amount, and when the light amount to the subject reaches the reference light amount, the still image recording operation is executed. And a recording execution means for recording a still image.
[0017]
A still image recording apparatus for an electronic endoscope apparatus according to the present invention is an electronic endoscope apparatus including a video scope having an image sensor and a processor to which a video scope and a display monitor are connected, and a moving image of a subject. In order to display an image on a monitor, a moving image display unit that reads and processes an image signal corresponding to the subject from the image sensor at predetermined time intervals, and a light amount that adjusts the amount of light emitted from the light source to illuminate the subject In a still image recording apparatus for an electronic endoscope apparatus having an adjustment means and a recording execution operation member for executing recording of a still image, a predetermined time is determined in accordance with an operation on the operation member in order to record a still image of a subject. Still image that reads and processes the image signal corresponding to the subject from the image sensor by the electronic shutter operation at the electronic shutter speed corresponding to the time shorter than the interval Recording means, and the still image recording means tentatively displays a still image on the monitor, so that a temporary still image display means for executing a still image display operation immediately after the recording execution operation member is operated, and a subject A light quantity increasing means for controlling the light quantity adjustment means so that the light quantity reaches a reference light quantity corresponding to still image recording, a standby means for waiting for execution of the still image recording operation until the light quantity to the subject reaches the reference light quantity, And a recording execution means for recording a still image by executing a still image recording operation when the light amount to the subject reaches a reference light amount.
[0018]
The program of the present invention is an electronic endoscope apparatus including a video scope having an image sensor and a processor to which the video scope and a display monitor are connected, and displays a moving image of the subject on the monitor. A moving image display unit that reads out and processes an image signal corresponding to a predetermined time interval from the image sensor, a light amount adjustment unit that adjusts the amount of light emitted from the light source to illuminate the subject, and a still image recording In order to record a recording execution operation member for execution and a still image of the subject, according to the operation on the operation member, an electronic shutter operation corresponding to a time shorter than a predetermined time interval is performed according to the subject from the image sensor by the electronic shutter operation. In order to execute still image recording processing in an electronic endoscope apparatus provided with still image recording means for reading and processing image signals A program that temporarily displays a still image on a monitor, so that a provisional still image display unit that executes a still image display operation immediately after a recording execution operation member is operated, and a recording of a still image in which the amount of light to the subject is recorded A light intensity increasing means for controlling the light intensity adjusting means so as to reach a reference light intensity corresponding to, a standby means for waiting for execution of a still image recording operation until the light intensity to the subject reaches the reference light intensity, and the light intensity to the subject is the reference light intensity. In this case, a recording execution means for recording a still image is executed by executing a still image recording operation.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an electronic endoscope apparatus according to an embodiment of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 is a block diagram of an electronic endoscope apparatus according to the first embodiment.
[0021]
The electronic endoscope apparatus includes a video scope 50 having a CCD 54 that is an image sensor and a processor 10 that processes an image signal read from the CCD 54, and displays an image of an observation site as a moving image or a still image. A monitor 60 is connected to the processor 10. The video scope 50 can be detachably connected to the processor 10, and a video recorder 70 and a video printer 80 are connected to the processor 10.
[0022]
When a lamp lighting switch (not shown) is turned on, electric power is supplied from the lamp power source 36 to the light source lamp 34 to light it. Light emitted from the light source lamp 34 that has been lit enters the incident end of the optical fiber bundle 56 provided in the video scope 50 via a condenser lens (not shown) and the diaphragm 33. The optical fiber bundle 56 is an optical fiber that transmits the light emitted from the light source lamp 34 to the distal end side of the video scope 50 having the observation site S, and the light that has passed through the optical fiber bundle 56 is emitted from the emission end 56B. The light emitted from the emission end 56B is applied to the observation site S through a light distribution lens (not shown) that is a diffusion lens.
[0023]
The light reflected at the observation site S passes through an objective lens (not shown) and reaches the light receiving surface of a CCD (Charge-Coupled Device) 54, whereby a subject image of the observation site S is formed on the light receiving surface of the CCD 54. The In this embodiment, a single-plate simultaneous type is applied as a color imaging method, and yellow (Ye), cyan (Cy), magenta (Mg), and green (G) color elements are checked on the light receiving surface of the CCD 54. Complementary color filters (not shown) arranged in a line are arranged so as to correspond to the respective pixels on the light receiving surface. In the CCD 54, an analog image signal of a subject image corresponding to a color passing through a complementary color filter is generated by photoelectric conversion, and an image signal of one field (one frame) is sequentially read out at a predetermined time interval according to a color difference line sequential method. . As the color television system, for example, the NTSC system is applied, and an image signal for one field (one frame) is sequentially read out for displaying a moving image every 1/60 second interval (1/30 second interval). And sent to the processor 10 via the signal line IC. The CCD 54 is driven by a CCD drive circuit 52, and a pulse signal for reading an image signal is output from the CCD drive circuit 52.
[0024]
The image signal input to the processor 10 is amplified by a not-shown preceding circuit and then sent to the A / D converter 22. In the A / D converter 22, the analog image signal is converted into a digital image signal, and the digital image signal is sent to the signal processing circuit 24. The signal processing circuit 24 performs various signal processing such as R, G, B gain processing and gamma correction on the digital image signal, and generates a luminance signal based on the image signal. A digital image signal for one frame is sequentially stored in a memory 26 which is a field memory, while a luminance signal is sequentially sent to a system control circuit 30 including a CPU (Central Processing Unit). When the digital image signal is read from the memory 26, the digital image signal is converted into an analog image signal by the D / A converter 28. The analog image signal is subjected to predetermined signal processing in a not-shown subsequent circuit and is output to the monitor 60 as a video signal such as an NTSC composite signal, a Y / C separation signal (S video signal), or an RGB separation signal. Thus, the subject image is displayed on the monitor 60 as a moving image.
[0025]
The system control circuit 30 controls the entire processor 10 and outputs a control signal to each circuit such as the signal processing circuit 24, the aperture control circuit 32, and the CCD drive circuit 52. A ROM (not shown) in the system control circuit 30 stores a program for executing still image recording processing during the freeze operation and controlling the operation of the entire processor. In a timing control circuit (not shown), a clock pulse for adjusting a signal processing timing is output to each circuit in the processor 10.
[0026]
Between the incident end of the light guide 56 and the condensing lens, a diaphragm 33 for adjusting the amount of light irradiated to the subject S is provided, and is opened and closed under the control of the diaphragm control circuit 32. Based on the luminance signal sent from the signal processing circuit 24 to the system control circuit 30, a control signal is output from the system control circuit 30 to the aperture control circuit 32. The diaphragm control circuit 32 drives a motor (not shown) based on the control signal, and thereby the diaphragm 33 connected to the motor opens and closes.
[0027]
The video scope 50 is provided with a freeze switch button 58, and when the freeze switch button 58 is pressed by the operator, an operation signal generated by the pressing operation is sent to the system control circuit 30 of the processor 10. Then, a freeze operation is executed based on the detected operation signal. That is, an image signal is read from the CCD 54 by an electronic shutter operation at a predetermined electronic shutter speed, and is processed by the A / D converter 22, the signal processing circuit 24, and the like. The processed image signal for one frame is stored in the memory 26 for recording a still image.
[0028]
The image signal for one frame stored in the memory 26 is recorded in the image recording memory 75 and transmitted to the video recorder 70 and the video printer 80 as a video signal. The video recorder 70 is a recording device for recording a still image, and the video printer 80 prints a still image based on the video signal sent during the freeze operation. While a still image is being recorded, the image signal stored in the memory 26 is not updated, and a new writing process is not performed. As a result, a still image is displayed on the monitor 60. Further, as will be described later, a still image is temporarily displayed from when the freeze switch button 58 is pressed until a still image is actually recorded. When the operator releases the freeze switch button 58 from the finger, the freeze operation is terminated, and the normal observation mode for displaying a moving image is resumed.
[0029]
FIG. 2 is a flowchart showing an operation process of the processor 10 in this embodiment. This flowchart is started when the main power supply of the processor 10 is turned on.
[0030]
In step S101, the aperture 33, the gain coefficient in signal processing, and the like are set to initial values, and the electronic shutter speed during the freeze operation is also set to a predetermined value. In step S102, normal observation, that is, processing for displaying a moving image on the monitor 60 is performed. In the normal observation mode, automatic light control processing is executed so that the brightness of the displayed subject image is constant, and here, interrupt calculation processing is executed every 1/60 second interval. When step S102 is executed, the process proceeds to step S103.
[0031]
In step S103, it is determined whether the freeze switch button 58 of the video scope 50 has been pressed by the operator. If it is determined that the freeze switch button 58 has not been pressed, the process returns to step S102. On the other hand, if it is determined that the freeze switch button 58 has been pressed, the process proceeds to step S104. In step S104, a freeze operation process is executed, and a still image is output to the video recorder 70 and the like and displayed on the monitor 60.
[0032]
FIG. 3 is a diagram showing a subroutine of the freeze operation process in step S104 of FIG. 2, and FIG. 4 is a diagram showing the level of the luminance signal during the freeze operation in time series.
[0033]
In the present embodiment, when a still image is recorded, the light amount is adjusted so that the brightness of the subject image during normal observation is the same as that during the freeze operation. That is, the light amount adjustment is performed so that the charge accumulation amount in each pixel of the CCD 54 when the subject image is frozen is the same as the charge accumulation amount in each corresponding pixel of the CCD 54 when the same subject image is normally observed. Since the image signal is read from the CCD 54 at intervals of 1/60 seconds during normal observation, the electronic shutter speed at the time of recording a still image is set to 1/120 seconds. However, the electronic shutter speed corresponds to the exposure time of the CCD 54 when recording a still image. Since the electronic shutter speed is twice as fast as the moving image display signal readout time interval (= 1/60 seconds) (exposure time is half), the amount of light to be irradiated on the subject during the freeze operation, that is, The amount of light that should be incident on the light receiving surface of the CCD 54 is twice the amount of light during normal observation.
[0034]
In FIG. 4, the level of the luminance signal detected by the system control circuit 30 is shown in time series, and the amount of light passing through the diaphragm 33 (hereinafter referred to as “passing amount of light”) is represented by the luminance signal level. ing. During normal observation, the luminance signal level detected from the image signal, that is, the luminance value Y is maintained at a luminance value Y1 (hereinafter referred to as a moving image reference luminance value) indicating an appropriate brightness reference of the subject image. Are automatically dimmed. However, the luminance value is determined as an integer value between 0 and 255 when the brightness of the subject image is classified in 256 levels. In addition, the luminance value here indicates an average luminance value, and is calculated by dividing the sum of the multipliers of the number of pixels and the luminance value in each luminance value from 0 to 255 by the number of pixels for one field.
[0035]
In the present embodiment, it is determined whether or not the light amount to the subject reaches twice the light amount (reference light amount) using the luminance value Y detected every 1/60 second interval as a determination reference. That is, it is determined whether or not the luminance value Y has reached a luminance value Y2 (hereinafter referred to as a still image reference luminance value) that is twice the moving image reference luminance value Y1.
[0036]
In step S201, a control signal is output to the aperture control circuit 32 so that the aperture 33 that has been opened to a predetermined opening during normal observation is further opened. At this time, the diaphragm 33 is controlled to gradually open. In step S202, a temporary display operation is executed. That is, in order to temporarily display a still image on the monitor 60, an image signal for one frame for displaying a still image is stored in the memory 26. At this time, an electronic shutter operation with an electronic shutter speed of 1/60 seconds is executed. When the image signal for displaying the temporary still image is stored in the memory 26, the rewriting process of the memory 26 is not performed until a recording operation described later is executed. As a result, a still image for temporary display is displayed on the monitor 60. The aperture 33 gradually opens until the image signal for one frame for still image display is stored in the memory 26 in step S202 after the control signal is output so that the aperture 33 is further opened in step S201. Therefore, the brightness of the displayed temporary image for temporary display hardly changes from the brightness of the moving image during normal observation. Note that while displaying the provisional still image, the image signal is read from the CCD 54 at 1/60 second intervals in order to calculate the luminance value Y. In step S203, the luminance value Y is sequentially calculated based on the luminance signal generated from the image signal for one field read from the CCD 54. When step S203 is executed, the process proceeds to step S204.
[0037]
In step S204, it is determined whether or not the calculated luminance value Y is equal to the still image reference luminance value Y2. If it is determined that the brightness value Y is not equal to the still image reference brightness value Y2, the process returns to step S203, and steps S203 and S204 are repeated until the brightness value Y becomes equal to the still image reference brightness value Y2. On the other hand, if it is determined that the luminance value Y is equal to the still image reference luminance value Y2, the process proceeds to step S205, and a control signal is output to the aperture control circuit 32 so as to stop the opening operation for opening the aperture 33. When step S205 is executed, the process proceeds to step S206.
[0038]
In step S206, the electronic shutter speed is 1/120 seconds after a delay time TR that takes into account the time from when the control signal is output so as to stop the opening operation of the diaphragm 33 until the diaphragm 33 actually stops. A control signal is sent to the CCD drive circuit 52 so that the shutter operation is executed. Based on the control signal from the system control circuit 30, the CCD drive circuit 52 outputs a charge sweep pulse signal to the CCD 54 so that the exposure time is 1/120 seconds. In step S207, an image signal corresponding to a still image of one frame captured at an electronic shutter speed of 1/120 seconds is stored in the memory 26, and the still image is output to the image recording memory 75 and the video recorder 70. The At the same time, the provisional display still image displayed by the execution of step S202 is updated in step S207, and the still image actually captured and recorded at the electronic shutter speed 1/120 second is displayed on the monitor 60. The While recording a still image, the electronic shutter speed, that is, the exposure time is half of the exposure time during normal observation, so the luminance value Y of the image signal is substantially equal to the luminance value Y1 during normal observation. Further, the image signal for one frame stored in the memory 26 is not rewritten until the freeze switch button 58 is turned off. When step S207 is executed, this subroutine ends, and the process proceeds to step S105 in FIG.
[0039]
In step S105, it is determined whether or not the freeze switch button 58 is in an OFF state when the operator removes the finger from the freeze switch button 58. If it is determined that the freeze switch button 58 is not in the OFF state, the process returns to step S104. On the other hand, if it is determined that the freeze switch button 58 is in the OFF state, the process proceeds to step S106, the freeze operation process is canceled, and the process returns to step S103. Steps S102 to S106 are repeatedly executed until the main power is turned off.
[0040]
As described above, according to the present embodiment, when the freeze switch button 58 is operated by the operator, the diaphragm 33 is opened so that the amount of light to the subject is double that in normal observation. The electronic shutter operation is not executed until the luminance value Y corresponding to the amount of light to the subject reaches the still image reference luminance value Y2. When the luminance value Y reaches the still image reference luminance value Y2, an electronic shutter operation is executed, and an electronic shutter speed (= 1/120 seconds) that is twice the image signal readout time interval (= 1/60 seconds) during normal observation. The image signal is read out, and the still image is recorded in the image recording memory 75 and the video recorder 70.
[0041]
In the present embodiment, the freeze switch button 58 is operated, and at the same time, an image signal for still image display is temporarily stored in the memory 26. The temporary still image is displayed on the monitor 60 until the still image that is actually recorded is displayed. Therefore, the brightness of the image on the monitor does not increase suddenly with the opening operation of the diaphragm 33.
[0042]
In the present embodiment, the electronic shutter speed is set to 1/120 seconds so that the brightness during normal observation and the brightness of the recorded still image coincide with each other, but video is read according to the image signal readout time interval during normal observation. The electronic shutter speed may be determined so that image quality degradation due to camera shake of the scope or movement of the observation site itself is not noticeable. For example, when a PAL system with a reading time interval of 1/50 second is applied as a color television system, the electronic shutter speed may be set to 1/100 second.
[0043]
The electronic shutter speed may be set so that the brightness of the still image becomes the brightness desired by the operator. In this case, the still image reference luminance value Y2 is set to a predetermined value according to the set shutter speed. Further, the electronic shutter speed may be configured to be changed by an operator's operation. As the brightness value Y and the reference brightness values Y1 and Y2, representative values other than the brightness average value may be applied.
[0044]
In the present embodiment, the diaphragm 33 is applied to the light amount adjustment, but the light amount may be adjusted by other configurations. For example, a liquid crystal plate or a polarizing plate may be applied to adjust the light amount by voltage control. Alternatively, a light emitting diode may be applied as the light source, and the light amount may be adjusted by controlling the light emission amount of the light emitting diode. In this case, when the luminance value Y reaches the still image reference luminance value Y2, it is possible to immediately perform the electronic shutter operation and perform the image recording operation without providing the delay time TR.
[0045]
Next, a second embodiment will be described with reference to FIGS. In the second embodiment, unlike the first embodiment, the electronic shutter operation is executed simultaneously with the opening operation of the diaphragm 33. Other configurations are substantially the same as those in the first embodiment.
[0046]
FIG. 5 shows the subroutine of step S104 of FIG. 2 in the second embodiment, and FIG. 6 is a diagram showing the luminance signal levels in the second embodiment in time series. When the freeze switch button 58 is operated, execution of the freeze operation process is started.
[0047]
In step S301, a control signal is output to the aperture control circuit 32 so that the aperture 33 is opened in accordance with an operation on the freeze switch button 58. In step S302, the electronic shutter operation is executed simultaneously with the opening operation of the diaphragm 33. In step S303, in order to temporarily display a still image on the monitor 60, an image signal corresponding to the still image for one frame is stored in the memory 26, and the image signal stored in the memory 26 is output to the monitor 60. . Until the recording operation is executed, the rewriting process of the memory 26 is not performed.
[0048]
In step S304, the luminance value Y is calculated based on the read image signal. As shown in FIG. 6, since the electronic shutter operation is performed simultaneously with the opening of the diaphragm 33, the detected luminance value Y instantaneously becomes half the luminance value Y1 during normal observation, and the diaphragm 33 gradually opens. Accordingly, the detected luminance value Y gradually increases. In the second embodiment, the moving image reference luminance value Y1 and the still image reference luminance value Y2 are equal.
[0049]
In step S305, it is determined whether the luminance value Y is equal to the still image reference luminance value Y2. If it is determined that the luminance value Y is not equal to the reference luminance value Y1, the process returns to step S304. On the other hand, when it is determined that the luminance value Y is equal to the still image reference luminance value Y2, the process proceeds to step S306, and the opening operation of the diaphragm 33 is stopped (see FIG. 6). In step S307, the still image recording operation is executed, the image signal obtained by the electronic shutter operation is stored in the memory 26, and the still image is recorded in the image recording memory 75 and the video recorder 70. At the same time, the temporary display still image displayed by the execution of step S303 is updated in step S307, and the actually recorded still image is displayed on the monitor 60. When step S307 is executed, this subroutine ends.
[0050]
As described above, according to the second embodiment, when the freeze switch button 58 is operated, the electronic shutter operation is executed simultaneously with the aperture 33 being gradually opened. When the detected luminance value Y becomes equal to the still image reference luminance value Y2, a still image recording operation is executed and a still image is recorded.
[0051]
【The invention's effect】
As described above, according to the present invention, a still image with appropriate brightness can be obtained without repeatedly performing the freeze operation, and an image that does not hinder the subject observation during the freeze operation is displayed on the monitor. be able to.
[Brief description of the drawings]
FIG. 1 is a block diagram of an electronic endoscope apparatus according to a first embodiment.
FIG. 2 is a flowchart showing a main operation process of a processor.
FIG. 3 is a diagram showing a subroutine of freeze operation processing in step S104 of FIG.
FIG. 4 is a diagram showing luminance signal levels in time series during a freeze operation.
FIG. 5 is a diagram showing a subroutine of freeze operation processing in the second embodiment.
FIG. 6 is a diagram showing the level of a luminance signal in a time series during a freeze operation in the second embodiment.
[Explanation of symbols]
10 processor 24 signal processing circuit 26 memory 30 system control circuit 32 aperture control circuit 33 aperture (light quantity adjusting means)
50 Videoscope 52 CCD drive circuit 54 CCD (imaging device)
58 Freeze switch button 60 Monitor 70 Video recorder 75 Image recording memory Y Luminance value Y1 Moving image reference luminance value Y2 Still image reference luminance value

Claims

An electronic endoscope apparatus comprising a video scope having an image sensor and a processor to which the video scope and a display monitor are connected,
In order to display a moving image of a subject on the monitor, a moving image display unit that reads and processes an image signal corresponding to the subject from the imaging element at predetermined time intervals;
A light amount adjusting means for adjusting the amount of light emitted from the light source to illuminate the subject;
A recording execution operation member for executing still image recording;
In order to record a still image of a subject, an image signal corresponding to the subject is read from the image sensor by an electronic shutter operation at an electronic shutter speed corresponding to a time shorter than the predetermined time interval in accordance with an operation on the recording execution operation member. A still image recording means for processing,
The still image recording means,
In order to temporarily display a temporary still image on the monitor, a temporary image display operation is executed based on an image signal read from the image sensor by the moving image display means when the recording execution operation member is operated. A still image display means;
A light amount increasing means for driving the light amount adjusting means to increase the light amount so that the light amount to the subject reaches a reference light amount corresponding to recording of a still image;
Standby means for waiting for execution of a still image recording operation until the light amount to the subject reaches the reference light amount;
If the light amount to the subject has reached the reference amount of light, it has a recording execution means for recording a still image by executing the still picture recording operation,
The provisional still image display means displays the provisional still image from when the recording execution operation member is operated until the still image recording operation is executed,
An electronic endoscope apparatus, wherein the still image recording means displays a recorded still image on the monitor when a still image recording operation is executed .

The light amount adjusting means is an aperture;
2. The electronic endoscope apparatus according to claim 1, wherein the light amount increasing means opens the diaphragm until the light amount to the subject reaches the reference light amount.

The electronic endoscope apparatus according to claim 2, wherein the light quantity increasing unit gradually opens the diaphragm.

The reference light amount is determined based on a ratio between a time corresponding to the electronic shutter speed and the predetermined time interval so that the brightness of the still image and the brightness of the moving image are substantially equal. The electronic endoscope apparatus according to claim 1.

The standby unit includes a light amount determination unit that determines whether or not the light amount to the subject has reached the reference light amount based on a luminance value calculated from an image signal read from the image sensor. The electronic endoscope apparatus according to claim 1.

Automatic light control processing means for controlling the light amount adjusting means based on a moving image reference luminance value serving as a brightness reference so that the brightness of the moving image is constant;
The standby unit includes a luminance value determining unit that determines whether or not a luminance value calculated from an image signal read from the image sensor has reached a still image reference luminance value corresponding to the reference light amount. The electronic endoscope apparatus according to claim 1.

The standby unit does not execute the electronic shutter operation and the still image recording operation until the light amount to the subject reaches the reference light amount,
2. The electronic endoscope apparatus according to claim 1, wherein when the light amount to the subject reaches the reference light amount, the recording execution unit causes the electronic shutter operation and the still image recording operation to be executed.

The standby means does not execute the still image recording operation while executing the electronic shutter operation until the light amount to the subject reaches the reference light amount,
2. The electronic endoscope apparatus according to claim 1, wherein when the light amount to the subject reaches the reference light amount, the recording execution unit executes the still image recording operation.

A video scope having a recording execution operation member and an image sensor for recording a still image, and a processor of an electronic endoscope apparatus to which the video scope and a display monitor are connected,
In order to display a moving image of a subject on the monitor, a moving image display unit that reads and processes an image signal corresponding to the subject from the imaging element at predetermined time intervals;
A light amount adjusting means for adjusting the amount of light emitted from the light source to illuminate the subject;
In order to record a still image of a subject, an image signal corresponding to the subject is read from the image sensor and processed by an electronic shutter operation at an electronic shutter speed corresponding to a time shorter than the predetermined time interval in accordance with an operation on the operation member. A still image recording means,
The still image recording means,
In order to temporarily display a temporary still image on the monitor, a temporary image display operation is executed based on an image signal read from the image sensor by the moving image display means when the recording execution operation member is operated. A still image display means;
A light amount increasing means for driving the light amount adjusting means to increase the light amount so that the light amount to the subject reaches a reference light amount corresponding to recording of a still image;
Standby means for waiting for execution of a still image recording operation until the light amount to the subject reaches the reference light amount;
If the light amount to the subject has reached the reference amount of light, it has a recording execution means for recording a still image by executing the still picture recording operation,
The provisional still image display means displays the provisional still image from when the recording execution operation member is operated until the still image recording operation is executed,
The processor of an electronic endoscope apparatus, wherein the still image recording means displays a recorded still image on the monitor when a still image recording operation is executed .

An electronic endoscope apparatus comprising a video scope having an image sensor and a processor to which the video scope and a display monitor are connected, and displays a moving image of a subject on the monitor. A moving image display means for reading out signals from the image sensor at predetermined time intervals and processing them, a light quantity adjusting means for adjusting the quantity of light emitted from the light source to illuminate the subject, and recording a still image In the still image recording apparatus for an electronic endoscope apparatus provided with the recording execution operation member,
In order to record a still image of a subject, an image signal corresponding to the subject is read from the image sensor and processed by an electronic shutter operation at an electronic shutter speed corresponding to a time shorter than the predetermined time interval in accordance with an operation on the operation member. comprising a still image recording means,
The still image recording means,
In order to temporarily display a temporary still image on the monitor, a temporary image display operation is executed based on an image signal read from the image sensor by the moving image display means when the recording execution operation member is operated. A still image display means;
A light amount increasing means for driving the light amount adjusting means to increase the light amount so that the light amount to the subject reaches a reference light amount corresponding to recording of a still image;
Standby means for waiting for execution of a still image recording operation until the light amount to the subject reaches the reference light amount;
If the light amount to the subject has reached the reference amount of light, it has a recording execution means for recording a still image by executing the still picture recording operation,
The provisional still image display means displays the provisional still image from when the recording execution operation member is operated until the still image recording operation is executed,
The still image recording apparatus for an electronic endoscope apparatus, wherein the still image recording means displays a recorded still image on the monitor when a still image recording operation is executed .

An electronic endoscope apparatus comprising a video scope having an image sensor and a processor to which the video scope and a display monitor are connected, and displays a moving image of a subject on the monitor. A moving image display means for reading out signals from the image sensor at predetermined time intervals and processing them, a light quantity adjusting means for adjusting the quantity of light emitted from the light source to illuminate the subject, and recording a still image In order to record a still image of the subject and the recording execution operation member of the image pickup device, according to the operation on the operation member, an electronic shutter operation with an electronic shutter speed corresponding to a time shorter than the predetermined time interval corresponds to the subject from the imaging device. A still image recording process is executed in an electronic endoscope apparatus including a still image recording unit that reads and processes an image signal. A program,
In order to temporarily display a temporary still image on the monitor, a temporary image display operation is executed based on an image signal read from the image sensor by the moving image display means when the recording execution operation member is operated. A still image display means;
A light amount increasing means for driving the light amount adjusting means to increase the light amount so that the light amount to the subject reaches a reference light amount corresponding to recording of a still image;
Standby means for waiting for execution of a still image recording operation until the light amount to the subject reaches the reference light amount;
When the amount of light to the subject reaches the reference amount of light, the recording execution unit that performs the still image recording operation to record a still image functions .
The temporary still image display means functions so as to display the temporary still image from when the recording execution operation member is operated until the still image recording operation is executed,
A program for causing the still image recording means to function so that a recorded still image is displayed on the monitor when a still image recording operation is executed .