JP3988208B2

JP3988208B2 - Solid-state imaging device and imaging method thereof

Info

Publication number: JP3988208B2
Application number: JP14418497A
Authority: JP
Inventors: 浩史森
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 1997-06-02
Filing date: 1997-06-02
Publication date: 2007-10-10
Anticipated expiration: 2017-06-02
Also published as: JPH10336525A

Description

【０００１】
【発明の属する技術分野】
本発明は、固体撮像装置、例えば、電荷蓄積期間を複数の期間に分割し、入射光量、画像のコントラストなどに応じて分割した複数の期間の内少なくとも一つの期間における露光時間を制御することにより、各期間の入射光量−感度特性を制御し、入射光量に対して飽和しにくく、ダイナミックレンジが広くできる固体撮像装置およびその撮像方法に関するものである。
【０００２】
【従来の技術】
ＣＣＤ（Charge Coupled Device:電荷結合デバイス）などを用いた固体撮像装置において、フォトダイオードなどの受光素子を用いて、撮像対象物からの入射光に応じて電荷を蓄積し、転送素子などにより蓄積した信号電荷を時系列の電気信号に変換し、画像信号として出力する。
【０００３】
図７は従来の固体撮像装置の一構成例を示すブロック図である。
図示のように、本例の固体撮像装置は、対物レンズ１０、光学フィルタ２０、固体撮像素子３０、信号処理回路４０、駆動回路５０、タイミング発生回路６０、同期信号発生回路７０、輝度信号検波回路８０および演算回路９０により構成されている。
【０００４】
同期信号発生回路７０により水平同期信号ＨＤと垂直同期信号ＶＤがそれぞれ発生される。タイミング発生回路６０は同期信号発生回路７０から水平同期信号ＨＤおよび垂直同期信号ＶＤに同期して動作し、固体撮像装置全体の動作タイミングを制御する駆動パルス信号Ｓ６０を発生する。駆動回路５０は、タイミング発生回路６０から駆動パルス信号Ｓ６０を電流増幅して、固体撮像素子３０に入力する。
【０００５】
撮像対象物からの入射光は、対物レンズ１０および光学フィルタ２０を介して固体撮像素子３０に照射される。固体撮像素子３０は、駆動回路５０により増幅された駆動パルス信号Ｓ５０により設定したタイミングで、入射光量に応じた電気信号である画像信号Ｓ３０を生成し、信号処理回路４０に出力する。信号処理回路４０は、固体撮像素子３０からの画像信号を処理して、それに同期信号発生回路７０からの水平同期信号ＨＤおよび垂直同期信号ＶＤを加えた後、ビデオ信号Ｓ_VDOとして出力する。
【０００６】
輝度信号検波回路８０は、信号処理回路４０において処理途中の輝度信号情報を含む映像信号（以下、単に輝度信号という）Ｓ４０を受けて、それを検波し、検波信号Ｓ８０を出力する。
演算回路９０は、輝度信号検波回路８０からの検波信号Ｓ８０を受けて、それに基づき画像の明るさ、コントラストや逆光状態の判定を行う。判定結果に応じて、シャッタスピードやＡＧＣの設定を行う制御信号Ｓ９０を発生し、対物レンズ１０、タイミング発生回路６０および信号処理回路４０にそれぞれ供給し、このフィードバックにより露光制御を行う。
【０００７】
図８は、従来の固体撮像装置に用いられている固体撮像素子３０の構造を示す配置図である。図示のように、固体撮像素子３０は、マトリクス状に配置された複数、例えば、（ｍ×ｎ、ｍ，ｎは正整数である）個の受光素子ＰＤ_1,1，ＰＤ_1,2，…，ＰＤ_1,n，ＰＤ_2,1，ＰＤ_2,2，…，ＰＤ_3,1，ＰＤ_3,2，…，ＰＤ_m,1，ＰＤ_m,2，…，ＰＤ_m,nにより構成されている受光部、受光部の列方向に連なって、受光素子の各列ごとに設けられている転送素子からなる垂直転送部３２、垂直転送部から送られてきた電荷を行方向に転送する転送素子からなる水平転送部３４、水平転送部の終端に設けられ、電荷の有無を検出する電荷検出アンプ３６、電荷検出アンプ３６からの信号を出力する出力アンプ３８により構成されている。
なお、垂直転送部３２は、例えば、マトリクス状に配置されている受光素子の列に応じて、マトリックスの列方向に配置されているｎ列の転送素子３２_-1，３２_-2，…，３２_-nにより構成されている。
【０００８】
即ち、固体撮像素子３０は一般的なインタライン方式の固体撮像素子で、垂直方向に隣り合った受光素子の信号電荷を垂直転送部の垂直転送素子内部で混合するフィールド読み出し動作を前提としている。
【０００９】
受光素子ＰＤ_1,1，ＰＤ_1,2，…，ＰＤ_1,n，ＰＤ_2,1，ＰＤ_2,2，…，ＰＤ_3,1，ＰＤ_3,2，…，ＰＤ_m,1，ＰＤ_m,2，…，ＰＤ_m,nは、例えば、露光期間（電荷蓄積期間）中に入射した光量に応じて所定量の電荷を蓄積するフォトダイオードなどの光センサにより構成され、垂直転送素子および水平転送素子は、例えば、レジスタにより構成されている。
出力アンプ３８からの出力信号は、固体撮像素子３０により発生した画像信号Ｓ３０である。
【００１０】
図９は固体撮像素子３０の動作タイミングを示す波形図、図１０は固体撮像素子３０における電荷転送および混合の動作を示す概念図である。以下、これらの図面を参照しつつ、本例の固体撮像素子３０における電荷蓄積、転送および混合動作について説明する。
図９に示すように、露光期間Ａに受光部の各受光素子に蓄積した電荷が時間Ｔ_RO1のタイミングで垂直転送部の転送素子（以下、単に垂直転送レジスタという）に読み出される。この動作は垂直転送レジスタ内の電荷転送が終了した後の垂直ブランキング期間に入って初めて可能となり、垂直ブランキング以外には行うことができない。また、この読み出し直後に空になった受光素子は次１フィールドの蓄積動作を開始する。
【００１１】
同一露光期間Ａに蓄積された信号電荷の内、奇数行の受光素子で蓄積した信号電荷と偶数行の受光素子で蓄積した信号電荷が垂直転送レジスタ内で混合されたのち、垂直転送、垂直レジスタ−水平レジスタ間転送および水平転送によって、露光期間Ａと露光期間Ｂにそれぞれ蓄積した信号電荷は時系列に電荷検出アンプ３６に転送され、電荷検出の結果が出力アンプ３８により増幅され、画像信号Ｓ３０として出力される。
【００１２】
【発明が解決しようとする課題】
ところで、上述した従来の固体撮像装置においては、１フィールドの画像を構成する各画素の蓄積期間は各フィールド当たり１期間のみで、入力光量に対する感度特性は図１１に示すように、一次の直線となる。この場合、入力光量がある程度大きくなると、受光素子の出力が飽和してしまい、画像の高輝度の部分が潰れてしまう。画像の飽和を回避するためには、電子シャッタなどの露光制御機能を利用して光量に対する感度特性を抑えてしまう使い方があるが、反対に暗い部分での感度が不足してしまい、十分な出力レベルを得ることができなくなる。即ち、１画面中の輝度レベルの差が大きい被写体を撮像する場合に、十分なダイナミックレンジを得ることができないという不利益がある。
【００１３】
また、図７に示すように、信号処理回路４０からの輝度信号Ｓ４０は輝度信号検波回路８０において積分処理やピーク検出などの処理が施され、輝度信号検波回路８０からの検波信号Ｓ８０は演算回路９０において、画像の明るさやコントラスト、逆光状態の判定などが行われる。演算回路９０において判定された画像状態に対して、電子シャッタのスピード制御や対物レンズ１０のメカアイリス制御、またはＡＧＣのゲイン制御などが自動的に行われるが、従来の固体撮像装置が選択できる露光設定は一通りであるため、１画面中の輝度レベルの差が大きい被写体を撮像する場合には、十分なダイナミックレンジを得ることができないという問題点が残ったままである。
【００１４】
本発明は、かかる事情に鑑みてなされたものであり、その目的は、画像状態の判定結果に応じて複数に分割された露光期間の感度比を任意に設定することで、入射光量に応じて感度特性を自由に設定でき、撮像状態に応じてダイナミックレンジを最適化できる固体撮像装置およびその撮像方法を提供することにある。
【００１５】
【課題を解決するための手段】
上記目的を達成するため、本発明の固体撮像装置は、電荷蓄積期間中に撮像対象物からの入射光に応じて受光素子に蓄積した電荷を転送部を介して転送し、画像信号として出力する固体撮像装置であって、上記電荷蓄積期間を少なくとも第１期間と第２期間の二つの期間に分割し、上記入射光量に応じて上記分割した期間の内、少なくとも一つの期間の時間長を制御する制御手段と、上記受光素子ごとに設けられ、各受光素子に蓄積した電荷を保持する電荷保持素子からなる電荷保持手段と、上記第１期間終了後の第１のタイミングで上記受光素子に蓄積した電荷を上記電荷保持手段に転送し保持させ、第２のタイミングで上記電荷保持手段に保持されている電荷を転送し、上記第２期間終了後の第３のタイミングで上記第２期間中に上記受光素子に蓄積した電荷を転送して出力させる転送制御手段とを有する。
【００１６】
また、本発明では、好適には上記画像信号を検波する検波手段を有し、上記制御手段は、当該検波手段の出力信号に応じて、上記分割した期間の内、少なくとも一つの期間の時間長を制御する。また、本発明の固体撮像装置は、上記受光素子に蓄積した電荷を保持する電荷保持手段と、上記第１期間終了後の第１のタイミングで上記受光素子に蓄積した電荷を上記保持手段に転送し保持させ、第２のタイミングで上記電荷保持手段に保持されている電荷を上記転送素子に転送し、上記第２期間終了後の第３のタイミングで上記第２期間中に上記受光素子に蓄積した電荷を上記転送素子に転送して出力させる転送制御手段とを有する。
【００１７】
また、本発明の固体撮像装置は、画素ごとに設けられ、マトリックス状に配置された複数の受光素子からなる受光部と、列方向に連なって上記受光部の受光素子列ごとに配置され、電荷蓄積期間中に撮像対象物からの入射光量に応じて上記受光素子に蓄積した電荷を列方向に転送する垂直転送部と、上記垂直転送部から送られてきた電荷を行方向に転送して、時系列の画像信号として出力する転送素子からなる水平転送部と、上記水平転送部により出力された画像信号を検波する検波手段と、上記電荷蓄積期間を少なくとも第１期間と第２期間の二つの期間に分割し、上記検波手段の出力信号に応じて上記分割した期間の内、少なくとも一つの期間の時間長を制御する露光時間制御手段と、上記受光部の受光素子ごとに設けられ、各受光素子に蓄積した電荷を保持する電荷保持素子からなる電荷保持手段と、上記第１期間終了後の第１のタイミングで当該第１期間中に上記受光部の受光素子に蓄積した電荷を上記電荷保持手段に転送し保持させ、第２のタイミングで上記電荷保持手段に保持されている電荷を上記垂直転送部に転送し、上記第２期間終了後の第３のタイミングで当該第２期間中に上記受光部の受光素子に蓄積した電荷を上記垂直転送部に転送する転送制御手段とを有する。
【００１８】
また、本発明の固体撮像装置は、画素ごとに設けられ、マトリックス状に配置された複数の受光素子からなる受光部と、列方向に連なって上記受光部の受光素子列ごとに配置され、電荷蓄積期間中に撮像対象物からの入射光量に応じて上記受光素子に蓄積した電荷を列方向に転送する垂直転送部と、上記垂直転送部から送られてきた電荷を行方向に転送して、時系列の画素信号として出力する転送素子からなる水平転送部と、上記水平転送部により出力された画素信号を検波する検波手段と、上記電荷蓄積期間を少なくとも第１期間と第２期間の二つの期間に分割し、上記検波手段の出力信号に応じて上記分割した期間の内、少なくとも一つの期間の時間長を制御する露光時間制御手段と、上記受光部の受光素子ごとに設けられ、各受光素子に蓄積した電荷を保持する電荷保持素子からなる電荷保持手段と、上記第１期間終了後の第１のタイミングで当該第１期間中に上記受光部の受光素子に蓄積した電荷を上記電荷保持手段に転送し保持させ、第２のタイミングで上記電荷保持手段に保持されている電荷の内、奇数行の受光素子で蓄積した電荷を上記垂直転送部に転送し、第３のタイミングで上記電荷保持手段に保持されている電荷の内、偶数行の受光素子で蓄積した電荷を上記垂直転送部に転送し、上記第２期間終了後の第４のタイミングで当該第２期間中に上記受光部の奇数行の受光素子に蓄積した電荷を上記垂直転送部に転送し、第５のタイミングで上記第２期間中に上記受光部の偶数行の受光素子に蓄積した電荷を上記垂直転送部に転送する制御手段とを有する。
【００１９】
また、本発明の固体撮像装置の撮像方法は、電荷蓄積期間中に撮像対象物からの入射光量に応じて受光素子に電荷を蓄積し、蓄積した電荷を垂直転送部に転送し、画像信号として出力する固体撮像装置の撮像方法であって、上記電荷蓄積期間を少なくとも第１期間と第２期間の二つの期間に分割し、上記入射光量に応じて上記分割した期間の内、少なくとも一つの期間の時間長を制御し、上記第１期間終了後の第１のタイミングで上記受光素子に蓄積した電荷を上記受光素子ごとに設けられた電荷保持素子からなる電荷保持手段に保持し、第２のタイミングで上記保持された電荷を上記垂直転送部に転送し、上記第２期間終了後の第３のタイミングで上記受光素子に蓄積した電荷を上記垂直転送部に転送する。
【００２０】
さらに、本発明の固体撮像装置の撮像方法は、マトリックス状に配置された複数の受光素子が電荷蓄積期間中に撮像対象物からの入射光量に応じて電荷を蓄積し、蓄積した電荷を上記受光素子の列ごとに配置された垂直転送部によって上記マトリックスの列方向に転送し、上記垂直転送部により送られてきた電荷を水平転送素子によって上記マトリックスの行方向に転送し、時系列の画像信号として出力する固体撮像装置の撮像方法であって、上記電荷蓄積期間を少なくとも第１期間と第２期間の二つの期間に分割し、上記画像信号に応じて上記分割した期間の内、少なくとも一つの期間の時間長を制御し、上記第１期間終了後の第１のタイミングで上記受光素子に蓄積した電荷を上記受光素子ごとに設けられた電荷保持素子からなる電荷保持手段に保持し、第２のタイミングで上記保持された電荷の内、奇数行の受光素子で蓄積した電荷を上記垂直転送部に転送し、第３のタイミングで上記保持された電荷の内、偶数行の受光素子で蓄積した電荷を上記垂直転送部に転送し、上記第２期間終了後の第４のタイミングで奇数行の受光素子に蓄積した電荷を上記垂直転送部に転送し、第５のタイミングで偶数行の受光素子に蓄積した電荷を上記垂直転送部に転送する。
【００２１】
本発明によれば、固体撮像装置の撮像期間は複数の、例えば、少なくとも二つの期間に分割され、入射光量に応じて分割した複数の期間の内、少なくとも一つの期間の露光時間が制御されるので、被写体からの入射光量および撮像条件、撮像目的などに応じて複数に分割した露光期間の感度比が任意に設定でき、固体撮像装置のダイナミックレンジの最適化が実現できる。
【００２２】
具体的に、例えば、画素ごとに設けられマトリックス状に配置された受光素子からなる受光部、露光期間中に受光素子に蓄積した信号電荷を垂直方向に転送および混合する垂直転送レジスタ、垂直転送レジスタから送られてきた信号電荷を水平方向に転送する水平転送レジスタからなる固体撮像素子に、水平転送レジスタから出力された画像信号の輝度信号を検波する検波手段が付け加えられ、検波手段の検波結果に応じて分割された複数の期間の内、少なくとも一つの期間における露光期間を制御することにより、各露光期間の感度比を設定でき、固体撮像装置のダイナミックレンジを最適化することができる。
【００２３】
また、分割された複数の期間の露光時間を自由に設定するため、固体撮像素子には、各受光部の受光素子ごとにそれぞれの受光素子の蓄積電荷を一時保持する電荷保持素子が設けられている。例えば、一例として、電荷蓄積時間が第１期間と第２期間の二つに分割した場合、第１期間終了後の第１のタイミングで各受光素子に蓄積した信号電荷がすべて電荷保持素子に転送される。そして、垂直転送レジスタにおける１フィールドの垂直転送が終了した後の第２のタイミングおよび第３のタイミングにおいて、電荷保持素子内の奇数行および偶数行の保持電荷が順次垂直転送レジスタに転送され、垂直転送レジスタにおいて混合される。さらに、第２期間終了後の第４および第５のタイミングにおいて、奇数行および偶数行の受光素子に蓄積した信号電荷が順次垂直転送レジスタに転送され、垂直転送レジスタにおいて混合された後、水平レジスタに転送され、さらに水平転送レジスタにより時系列の画像信号として出力される。
このように分割された複数の期間の露光時間が任意に設定することができ、固体撮像素子の入射光量−感度特性を任意に設定でき、ダイナミックレンジの最適化が実現できる。
【００２４】
【発明の実施の形態】
図１は本発明に係る固体撮像装置の一実施形態を示す回路図である。
図示のようにように、本例の固体撮像装置は、対物レンズ１０、光学フィルタ２０、固体撮像素子３０ａ、信号処理回路４０、駆動回路５０、タイミング発生回路６０ａ、同期信号発生回路７０、輝度信号検波回路８０および演算回路９０により構成されている。
【００２５】
本実施形態の固体撮像装置は、図７に示す従来の固体撮像装置と較べると、固体撮像素子３０ａ、タイミング発生回路６０ａを除けば、他の構成部分はほぼ同じ回路により構成されている。
ただし、本発明においては、固体撮像素子３０ａの構成および動作タイミングを工夫したことによって、電荷蓄積期間から分割された複数の期間の内、少なくとも一つの期間における露光時間を任意に設定することができ、これにより固体撮像装置における各露光期間の感度特性を自由に設定でき、高輝度領域における光量−感度特性の劣化を回避でき、ダイナミックレンジの最適化を実現した。また、改良が行われた固体撮像素子３０ａ動作タイミングを制御するため、タイミング発生回路６０ａはそれに応じた変更が行われる。
【００２６】
図１に示す固体撮像装置において、同期信号発生回路７０により水平同期信号ＨＤと垂直同期信号ＶＤがそれぞれ発生される。タイミング発生回路６０ａは同期信号発生回路７０からの水平同期信号ＨＤおよび垂直同期信号ＶＤに同期して動作し、固体撮像装置全体の動作タイミングを制御する駆動パルス信号Ｓ６０ａを発生する。駆動回路５０は、タイミング発生回路６０から駆動パルス信号Ｓ６０ａを電流増幅して、固体撮像素子３０ａに入力する。
【００２７】
撮像対象物からの入射光は、対物レンズ１０および光学フィルタ２０を介して固体撮像素子３０ａに照射される。固体撮像素子３０ａは、駆動回路５０により増幅された駆動パルス信号Ｓ５０により設定したタイミングで、入射光量に応じて画像信号Ｓ３０ａを生成し、信号処理回路４０に出力する。信号処理回路４０は、固体撮像素子３０ａからの画像信号を処理して、それに同期信号発生回路７０からの水平同期信号ＨＤおよび垂直同期信号ＶＤを加えた後、ビデオ信号Ｓ_ＶＤ０として出力する。
【００２８】
輝度信号検波回路８０は、信号処理回路４０において処理途中の輝度信号Ｓ４０を受けて、それを検波し、検波信号Ｓ８０を出力する。
演算回路９０は、輝度信号検波回路８０からの検波信号Ｓ８０を受けて、それに基づき画像の明るさ、コントラストや逆光状態の判定を行う。判定結果に応じて、シャッタスピード制御、対物レンズのメカアイリス制御またはＡＧＣのゲイン制御を行う制御信号Ｓ９０を発生し、対物レンズ１０、タイミング発生回路６０ａおよび信号処理回路４０にそれぞれ供給し、このフィードバックにより露光制御を行う。
【００２９】
図２は本実施形態における固体撮像素子３０ａの内部構成を示す配置図である。図示のように、固体撮像素子３０ａは、マトリクス状に配置された複数、例えば、（ｍ×ｎ）個の受光素子ＰＤ_1,1，ＰＤ_1,2，…，ＰＤ_1,n，ＰＤ_2,1，ＰＤ_2,2，…，ＰＤ_3,1，ＰＤ_3,2，…，ＰＤ_m,1，ＰＤ_m,2…，ＰＤ_m,nにより構成されている受光部を有し、さらに受光部に各受光素子ごとに電荷保持素子ＣＲ_1,1，ＣＲ_1,2，…，ＣＲ_1,n，ＣＲ_2,1，ＣＲ_2,2，…，ＣＲ_3,1，ＣＲ_3,2，…，ＣＲ_m,1，ＣＲ_m,2，…，ＣＲ_m,nが設けられ、これによって本実施形態の固体撮像装置にはそれぞれの受光素子の蓄積電荷を保持する電荷保持機能が加えられた。さらに、図７に示す従来の固体撮像装置と同様に、受光部の列方向に連なって、受光素子の各列ごとに設けられている転送素子からなる垂直転送部３２、垂直転送部から送られてきた電荷を行方向に転送する転送素子からなる水平転送部３４、水平転送部の終端に設けられ、電荷の有無を検出する電荷検出アンプ３６、電荷検出アンプ３６からの信号を出力する出力アンプ３８がそれぞれ設けられている。
【００３０】
受光素子ＰＤ_1,1，ＰＤ_1,2，ＰＤ_1,3，…，ＰＤ_1,n，ＰＤ_2,1，…，ＰＤ_3,1，…，ＰＤ_m,1…，ＰＤ_m,nは、例えば、露光期間中に入射した光量に応じて所定量の電荷を蓄積するフォトダイオードなどの光センサにより構成されている。電荷保持素子ＣＲ_1,1，ＣＲ_1,2，…，ＣＲ_1,n，ＣＲ_2,1，ＣＲ_2,2，…，ＣＲ_3,1，ＣＲ_3,2，…，ＣＲ_m,1，ＣＲ_m,2，…，ＣＲ_m,nは、受光素子に蓄積した電荷を一時保持する電荷保持素子からなり、その例として、例えば、レジスタまたはキャパシタにより構成することができる。
【００３１】
垂直転送部３２は、例えば、マトリクス状に配置されている受光素子の列に応じて、マトリックスの列方向に配置されているｎ列の転送素子３２_-1，３２_-2，…，３２_-nにより構成され、転送素子は、例えばレジスタにより構成されている。
水平転送部３４は、垂直転送部からの送られてきた電荷を水平方向（受光素子がなすマトリクスの行方向）に転送する水平転送素子からなる。なお、水平転送素子は、垂直転送素子と同様に、例えば、レジスタにより構成されている。
【００３２】
図３は本実施形態の固体撮像素子３０ａの動作タイミングを示す波形図、図４は固体撮像素子３０ａにおける電荷蓄積および電荷転送の動作を示す概念図である。以下、これらの図面を参照しつつ、本実施形態の固体撮像装置の電荷蓄積および転送動作について説明する。
図３に示すように、本実施形態の固体撮像素子３０ａにおける電荷蓄積期間を二つの期間、即ち、露光期間Ａ１と露光期間Ｂ１とに分割されている。露光期間Ａ１と露光期間Ｂ１は、通常動作期間と垂直ブランキング期間の間に、任意に配分されている。
露光期間Ａ１と露光期間Ｂ１の内、少なくとも一つの露光期間、例えば、露光期間Ａ１が図１に示す演算回路９０からの制御信号Ｓ９０に応じて設定可能であり、これにより、分割された各露光期間の入射光量−感度特性が任意に設定でき、各露光期間の間の感度比が自由に設定できる。
【００３３】
以下、露光期間Ａ１、Ｂ１の順で固体撮像素子３０ａの動作を説明する。
露光期間Ａ１に各受光素子に蓄積した電荷が時間Ｔ_RO1のタイミングで各受光素子ＰＤ_1,1，ＰＤ_1,2，…，ＰＤ_1,n，ＰＤ_2,1，ＰＤ_2,2，…，ＰＤ_3,1，ＰＤ_3,2，…，ＰＤ_m,1，ＰＤ_m,2…，ＰＤ_m,nからそれぞれの受光素子に応じて設けられている電荷保持素子ＣＲ_1,1，ＣＲ_1,2，…，ＣＲ_1,n，ＣＲ_2,1，ＣＲ_2,2，…，ＣＲ_3,1，ＣＲ_3,2，…，ＣＲ_m,1，ＣＲ_m,2，…，ＣＲ_m,nに読み出される。なお、この読み出し動作は垂直転送レジスタ内の信号電荷に影響を与えないため、垂直転送が終了したか否かに関わらず、任意のタイミングで行うことが可能である。また、この読み出し直後に空になった受光素子は次の蓄積動作を開始する。
【００３４】
図４は、固体撮像素子３０ａにおける受光素子ＰＤ_1,i，ＰＤ_2,i，…，ＰＤ_m,iからなる一行の受光素子、電荷保持素子ＣＲ_1,i，ＣＲ_2,i，…，ＣＲ_m,iからなる一行の電荷保持素子および垂直転送レジスタ３０_-iの電荷蓄積および転送動作を図示したものである。
同図（ａ）は、例として受光素子ＰＤ_1,i，ＰＤ_2,i，…，ＰＤ_m,iから電荷保持素子ＣＲ_1,i，ＣＲ_2,i，…，ＣＲ_m,iに信号電荷が転送される様子を示している。
【００３５】
次に、前フィールドの信号電荷の垂直転送が終了した後、図３に示す時間Ｔ_RO2のタイミングで各電荷保持素子の内、奇数行の受光素子により露光期間Ａ１に蓄積した信号電荷が垂直レジスタに読み出される。
図４（ｂ）に示すように、受光素子ＰＤ_1,i，ＰＤ_3,i，…などの奇数行の受光素子に対応した電荷保持素子ＣＲ_1,i，ＣＲ_3,i，…に保持されている電荷がそれぞれ垂直転送レジスタ３２_-iに転送される。
【００３６】
次に、垂直転送部において、垂直転送を一行分行った後に、時間Ｔ_RO3のタイミングで各電荷保持素子の内、偶数行の受光素子により露光期間Ａ１に蓄積した信号電荷が垂直レジスタに読み出される。
図４（ｃ）に示すように、受光素子ＰＤ_2,i，ＰＤ_4,i，…などの偶数行の受光素子に対応した電荷保持素子ＣＲ_2,i，ＣＲ_4,i，…に保持されている電荷がそれぞれ垂直転送レジスタ３２_-iに転送される。
これにより、同一露光期間Ａ１に蓄積された奇数行と偶数行の受光素子の信号電荷は垂直転送レジスタにおいて混合される。
【００３７】
次に、露光期間Ｂ１に蓄積された電荷の内、奇数行に相当する受光素子の蓄積電荷が時間Ｔ_RO4のタイミング各受光素子からそれぞれの受光素子に応じて設けられている垂直転送レジスタに読み出される。そして垂直転送部において垂直転送を一行分行った後に、時間Ｔ_RO5のタイミングで露光期間Ｂ１に蓄積された電荷の内、偶数行に相当する受光素子の蓄積電荷が各受光素子から垂直転送レジスタに読み出される。
これにより、同一露光期間Ｂ１に蓄積された奇数行と偶数行の受光素子の信号電荷は垂直転送レジスタにおいて混合される。
【００３８】
図４（ｄ）に示すように、受光素子ＰＤ_1,i，ＰＤ_3,i，…などの奇数行の受光素子に蓄積した信号電荷がそれぞれ垂直転送レジスタ３２_-iに転送される。図４（ｅ）に示すように、受光素子ＰＤ_2,i，ＰＤ_4,i，…などの偶数行の受光素子に蓄積した信号電荷がそれぞれ垂直転送レジスタ３２_-iに転送され、垂直転送レジスタ３２_-iにおいて、垂直転送で送られてきた奇数行の受光素子ＰＤ_1,i，ＰＤ_3,i，…により蓄積した信号電荷と混合される。
【００３９】
以上述べた一連の動作によって垂直転送レジスタには、露光期間Ａ１に蓄積された電荷と露光期間Ｂ１に蓄積された電荷が交互に保持される。そして、読み出しが完了した後、垂直転送、垂直レジスタ−水平レジスタ間転送および水平転送によって、露光期間Ａ１と露光期間Ｂ１に蓄積した信号電荷は時系列に電荷検出アンプ３６に転送され、電荷検出の結果が出力アンプ３８により増幅され、画像信号Ｓ３０ａとして出力される。
【００４０】
このように、露光期間Ａ１、Ｂ１のそれぞれの信号電荷は、それぞれの露光期間の違いから、入力光量に対して図５（ａ）、（ｂ）に示す光量−感度特性が得られる。そして、固体撮像素子３０ａの後段に設けられている信号処理回路４０によってこれらの信号に対して加算／補正処理が行われ、固体撮像装置全体の特性として、図５（ｃ）に示す光量−感度特性を得ることができる。
即ち、露光期間Ａ１および露光期間Ｂ１は任意に設定できるため、図５（ａ）および（ｂ）に示すように、それぞれの露光期間に対応した感度特性の傾きを任意に制御することができる。これに応じて固体撮像装置全体の光量−感度特性は図５（ｃ）に示すように、傾きが任意に設定でき、ダイナミックレンジの最適化制御が実現できる。
【００４１】
図１に示す本実施形態の固体撮像装置において、信号処理回路４０からの輝度信号Ｓ４０は輝度信号検波回路８０において積分処理やピーク検出などの処理が施され、輝度信号検波回路８０からの検波信号Ｓ８０は演算回路９０において、画像の明るさやコントラスト、逆光状態の判定などが行われる。演算回路９０において判定された画像状態に対して、電子シャッタのスピード制御や対物レンズ１０のメカアイリス制御、またはＡＧＣのゲイン制御などを行う制御信号Ｓ９０が生成され、これを対物レンズ１０、タイミング発生回路６０ａおよび信号処理回路４０にフィードバックすることにより、それぞれの制御が撮像条件および撮像目的に応じて自動的に行われる。
【００４２】
このような特徴を有する本実施形態の固体撮像装置において、検波回路８０からの検波信号Ｓ８０およびそれに基づいて演算回路９０で演算処理した結果に応じて生成した制御信号Ｓ９０によって、露光期間Ａ１と露光期間Ｂ１の感度比を任意に設定することができ、撮像状況および撮像目的になどに応じて固体撮像装置のダイナミックレンジを最適化することができる。
例えば、図６（ａ）に示すように画像のコントラストが小さく且つ全体に暗い状態では、露光期間Ａ１のみの露光設定としたり、同図（ｂ）のように画像のコントラストが小さいが全体に明るい状態では、露光期間Ａ１と露光期間Ｂ１の感度比を同じにするか露光期間Ａ１のみ（或いはＢ１のみ）の信号を使ったりすることが可能である。反対に同図（ｃ）に示すように画像のコントラストが大きい場合には露光期間Ａ１と露光期間Ｂ１の感度比を大きくすることで画像のダイナミックレンジを改善することができ、コントラストの度合いに応じて露光期間Ａ１および露光期間Ｂ１の感度比を変化させることも有効である。
【００４３】
以上説明したように、本実施形態によれば、入射光は対物レンズ１０、光学フィルタ２０を介して固体撮像素子３０ａに照射し、固体撮像素子３０ａは露光期間を複数に分割し各期間で蓄積信号電荷に応じた画像信号Ｓ３０ａを生成し、信号処理回路４０に入力する。同期信号発生回路７０により生成した水平および垂直同期信号ＨＤ，ＶＤはタイミング発生回路６０ａおよび信号処理回路４０にそれぞれ供給し、タイミング発生回路６０ａはそれに応じた同期駆動パルス信号Ｓ６０ａを生成し、駆動回路５０により増幅した後固体撮像素子３０ａに入力し、その動作タイミングを制御し、信号処理回路４０は、画像信号に同期信号を加えた複合映像信号Ｓ_ＶＤ０を出力する。輝度信号検波回路８０は信号処理回路４０からの輝度信号Ｓ４０を検波して検波信号Ｓ８０を出力し、演算回路９０は検波信号Ｓ８０を演算処理し、画像の明るさ、コントラストや逆光状態を判定し、制御信号Ｓ９０を生成し、対物レンズ１０、タイミング発生回路６０ａおよび信号処理回路４０にフィードバックし、露光制御を行うので、撮像の状態に応じてダイナミックレンジの最適化を実現できる。
【００４５】
【発明の効果】
以上説明したように、本発明の固体撮像装置およびその方法によれば、画像状態の判定結果に応じて複数に分割された露光期間の感度比を任意に設定することで、中低輝度領域と高輝度領域の光量−感度特性のバランスを自由に設定できるため、逆光状態やコントラストの大小などの被写体の状況に応じて撮像装置のダイナミックレンジを最適化できる利点がある。
【図面の簡単な説明】
【図１】本発明に係る固体撮像装置の一実施形態を示す回路図である。
【図２】本発明における固体撮像素子の内部構成を示す配置図である。
【図３】本発明における固体撮像素子の動作タイミングを示す波形図である。
【図４】本発明における固体撮像素子における電荷蓄積および電荷転送の動作を示す概念図である。
【図５】本発明の固体撮像装置の光量−感度特性を示すグラフである。
【図６】被写体の明るさ、コントラストの状況を示す概念図である。
【図７】従来の固体撮像装置の一例を示すブロック図である。
【図８】従来の固体撮像素子の内部構成を示す配置図である。
【図９】従来の固体撮像素子の動作タイミングを示す波形図である。
【図１０】従来の固体撮像素子における電荷蓄積および電荷転送の動作を示す概念図である。
【図１１】従来の固体撮像装置の光量−感度特性を示すグラフである。
【符号の説明】
１０…対物レンズ、２０…光学フィルタ、３０，３０ａ…固体撮像素子、４０…信号処理回路、５０…駆動回路、６０，６０ａ…タイミング発生回路、７０…同期信号発生回路、８０…輝度信号検波回路、９０…演算回路、ＰＤ_1,1，ＰＤ_1,2，…，ＰＤ_1,n，ＰＤ_2,1，ＰＤ_2,2，…，ＰＤ_3,1，ＰＤ_3,2，…，ＰＤ_m,1，ＰＤ_m,2…，ＰＤ_m,n…受光素子、ＣＲ_1,1，ＣＲ_1,2，…，ＣＲ_1,n，ＣＲ_2,1，ＣＲ_2,2，…，ＣＲ_3,1，ＣＲ_3,2，…，ＣＲ_m,1，ＣＲ_m,2，…，ＣＲ_m,n…電荷保持素子、３２…垂直転送部、３２_-1，３２_-2，…，３２_-n…垂直転送レジスタ、３４…水平転送分、３６…電荷検出アンプ、３８…出力アンプ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid-state imaging device, for example, by dividing the charge accumulation period into a plurality of periods and controlling the exposure time in at least one of the plurality of periods divided according to the incident light amount, image contrast, etc. The present invention relates to a solid-state imaging device that controls incident light amount-sensitivity characteristics in each period, is less likely to be saturated with respect to the incident light amount, and has a wide dynamic range, and an imaging method thereof.
[0002]
[Prior art]
In a solid-state imaging device using a CCD (Charge Coupled Device) or the like, charges are accumulated according to incident light from an imaging object using a light receiving element such as a photodiode, and accumulated by a transfer element or the like. The signal charge is converted into a time-series electric signal and output as an image signal.
[0003]
FIG. 7 is a block diagram showing a configuration example of a conventional solid-state imaging device.
As illustrated, the solid-state imaging device of this example includes an objective lens 10, an optical filter 20, a solid-state imaging device 30, a signal processing circuit 40, a drive circuit 50, a timing generation circuit 60, a synchronization signal generation circuit 70, and a luminance signal detection circuit. 80 and an arithmetic circuit 90.
[0004]
A synchronizing signal generating circuit 70 generates a horizontal synchronizing signal HD and a vertical synchronizing signal VD. The timing generation circuit 60 operates in synchronization with the horizontal synchronization signal HD and the vertical synchronization signal VD from the synchronization signal generation circuit 70, and generates a drive pulse signal S60 that controls the operation timing of the entire solid-state imaging device. The drive circuit 50 receives the drive pulse signal S60 from the timing generation circuit 60. Current amplification And input to the solid-state imaging device 30.
[0005]
Incident light from the imaging object is applied to the solid-state imaging device 30 via the objective lens 10 and the optical filter 20. The solid-state imaging device 30 generates an image signal S30 that is an electrical signal corresponding to the amount of incident light at a timing set by the drive pulse signal S50 amplified by the drive circuit 50, and outputs the image signal S30 to the signal processing circuit 40. The signal processing circuit 40 processes the image signal from the solid-state imaging device 30 and adds the horizontal synchronizing signal HD and the vertical synchronizing signal VD from the synchronizing signal generating circuit 70 to the video signal S. _VDO Output as.
[0006]
The luminance signal detection circuit 80 receives a video signal (hereinafter simply referred to as luminance signal) S40 including luminance signal information being processed in the signal processing circuit 40, detects it, and outputs a detection signal S80.
The arithmetic circuit 90 receives the detection signal S80 from the luminance signal detection circuit 80, and determines the brightness, contrast, and backlight state of the image based on the detection signal S80. A control signal S90 for setting the shutter speed and AGC is generated according to the determination result, and supplied to the objective lens 10, the timing generation circuit 60, and the signal processing circuit 40, and exposure control is performed by this feedback.
[0007]
FIG. 8 is a layout diagram showing the structure of a solid-state imaging device 30 used in a conventional solid-state imaging device. As shown in the drawing, the solid-state imaging device 30 includes a plurality of, for example, (m × n, m, n are positive integers) light receiving elements PD arranged in a matrix. _1,1 , PD _1,2 , ..., PD _{1, n} , PD _2,1 , PD _2,2 , ..., PD _3,1 , PD _3,2 , ..., PD _{m, 1} , PD _{m, 2} , ..., PD _{m, n} A vertical transfer unit 32 made up of transfer elements provided for each column of the light receiving elements, and the electric charges sent from the vertical transfer unit in the row direction. A horizontal transfer unit 34 including transfer elements to be transferred, a charge detection amplifier 36 that detects the presence / absence of charges, and an output amplifier 38 that outputs a signal from the charge detection amplifier 36 are provided at the end of the horizontal transfer unit.
Note that the vertical transfer unit 32 has, for example, n columns of transfer elements 32 arranged in the column direction of the matrix in accordance with the columns of light receiving elements arranged in a matrix. _-1 , 32 _-2 , ..., 32 _-n It is comprised by.
[0008]
That is, the solid-state imaging device 30 is a general interline type solid-state imaging device, and is premised on a field readout operation in which signal charges of light receiving elements adjacent in the vertical direction are mixed inside the vertical transfer element of the vertical transfer unit.
[0009]
Light receiving element PD _1,1 , PD _1,2 , ..., PD _{1, n} , PD _2,1 , PD _2,2 , ..., PD _3,1 , PD _3,2 , ..., PD _{m, 1} , PD _{m, 2} , ..., PD _{m, n} Is constituted by an optical sensor such as a photodiode that accumulates a predetermined amount of charge according to the amount of light incident during the exposure period (charge accumulation period), and the vertical transfer element and the horizontal transfer element are constituted by, for example, a register. Has been.
An output signal from the output amplifier 38 is an image signal S30 generated by the solid-state imaging device 30.
[0010]
FIG. 9 is a waveform diagram showing the operation timing of the solid-state image sensor 30, and FIG. 10 is a conceptual diagram showing charge transfer and mixing operations in the solid-state image sensor 30. Hereinafter, the charge accumulation, transfer, and mixing operations in the solid-state imaging device 30 of the present example will be described with reference to these drawings.
As shown in FIG. 9, the charge accumulated in each light receiving element of the light receiving portion during the exposure period A is changed to a time T. _RO1 At this timing, the data is read out to a transfer element of the vertical transfer unit (hereinafter simply referred to as a vertical transfer register). This operation is possible only after the vertical blanking period after the completion of charge transfer in the vertical transfer register, and cannot be performed except for vertical blanking. In addition, the light receiving element which becomes empty immediately after the readout starts the accumulation operation of the next one field.
[0011]
Of the signal charges accumulated in the same exposure period A, the signal charges accumulated in the odd-numbered light receiving elements and the signal charges accumulated in the even-numbered light receiving elements are mixed in the vertical transfer register, and then the vertical transfer, vertical register The signal charges accumulated in the exposure period A and the exposure period B are transferred to the charge detection amplifier 36 in time series by the horizontal register transfer and the horizontal transfer, and the charge detection result is amplified by the output amplifier 38, and the image signal S30. Is output as
[0012]
[Problems to be solved by the invention]
By the way, in the above-described conventional solid-state imaging device, an image of one field is formed. Accumulation period of each pixel Is only one period per field, and the sensitivity characteristics with respect to the input light amount are as shown in FIG. once It becomes a straight line. In this case, when the input light quantity increases to some extent, the output of the light receiving element is saturated, and the high-luminance portion of the image is crushed. To avoid image saturation, use an exposure control function such as an electronic shutter to reduce the sensitivity characteristic to the light quantity. On the other hand, the sensitivity in the dark part is insufficient and sufficient output is achieved. You can no longer get the level. That is, there is a disadvantage that a sufficient dynamic range cannot be obtained when an object with a large difference in luminance level in one screen is imaged.
[0013]
Further, as shown in FIG. 7, the luminance signal S40 from the signal processing circuit 40 is subjected to processing such as integration processing and peak detection in the luminance signal detection circuit 80, and the detection signal S80 from the luminance signal detection circuit 80 is calculated by an arithmetic circuit. At 90, image brightness, contrast, backlight status, etc. are determined. The electronic shutter speed control, the mechanical iris control of the objective lens 10, or the AGC gain control is automatically performed on the image state determined by the arithmetic circuit 90, but the exposure that can be selected by the conventional solid-state imaging device is performed. Since there is only one setting, there remains a problem that a sufficient dynamic range cannot be obtained when an object with a large difference in luminance level in one screen is imaged.
[0014]
The present invention has been made in view of such circumstances, and an object of the present invention is to arbitrarily set the sensitivity ratio of the exposure period divided into a plurality according to the determination result of the image state in accordance with the amount of incident light. An object of the present invention is to provide a solid-state imaging device capable of freely setting sensitivity characteristics and optimizing a dynamic range according to an imaging state and an imaging method thereof.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the solid-state imaging device according to the present invention is configured to store the charge accumulated in the light receiving element according to the incident light from the imaging target during the charge accumulation period. Transfer section The charge accumulation period is divided into at least two periods of a first period and a second period, and the divided period is divided according to the amount of incident light. Control means for controlling the time length of at least one period And charge holding means that is provided for each light receiving element and holds charge accumulated in each light receiving element, and charge accumulated in the light receiving element at a first timing after the end of the first period. Transfer to and hold the charge holding means, transfer the charge held in the charge holding means at a second timing, and the light receiving element during the second period at a third timing after the end of the second period Transfer control means for transferring and outputting the charge accumulated in Have
[0016]
In the present invention, preferably, the image processing apparatus further includes detection means for detecting the image signal, and the control means has a time length of at least one of the divided periods according to the output signal of the detection means. To control. The solid-state imaging device according to the present invention includes a charge holding unit that holds the charge accumulated in the light receiving element, and the charge accumulated in the light receiving element at a first timing after the end of the first period to the holding unit. The charge held in the charge holding means is transferred to the transfer element at a second timing, and accumulated in the light receiving element during the second period at a third timing after the end of the second period. Transfer control means for transferring the generated charge to the transfer element for output.
[0017]
Further, the solid-state imaging device of the present invention is provided for each pixel, and is arranged for each light receiving element row of the light receiving unit connected to the light receiving unit composed of a plurality of light receiving elements arranged in a matrix and in the column direction. The charge accumulated in the light receiving element in the column direction according to the amount of incident light from the object to be imaged during the accumulation period Vertical transfer section to transfer When, From the vertical transfer section A horizontal transfer unit composed of transfer elements that transfer the transmitted charge in the row direction and output it as a time-series image signal, a detection means for detecting the image signal output by the horizontal transfer unit, and the charge storage An exposure time control unit that divides a period into at least two periods of a first period and a second period and controls a time length of at least one of the divided periods according to an output signal of the detection unit; A charge holding element is provided for each light receiving element of the light receiving unit and holds charges accumulated in each light receiving element. The charge holding means transfers the charge accumulated in the light receiving element of the light receiving portion during the first period at the first timing after the end of the first period to the charge holding means and holds the charge at the second timing. The charge held in the charge holding means In the vertical transfer section Transfer control means for transferring and transferring the charge accumulated in the light receiving element of the light receiving portion during the second period at a third timing after the end of the second period to the vertical transfer portion.
[0018]
Further, the solid-state imaging device of the present invention is provided for each pixel, and is arranged for each light receiving element row of the light receiving unit connected to the light receiving unit composed of a plurality of light receiving elements arranged in a matrix and in the column direction. The charge accumulated in the light receiving element in the column direction according to the amount of incident light from the object to be imaged during the accumulation period Vertical transfer section to transfer When, From the vertical transfer section A horizontal transfer unit composed of a transfer element that transfers the transmitted charge in the row direction and outputs it as a time-series pixel signal, a detection means for detecting the pixel signal output by the horizontal transfer unit, and the charge accumulation An exposure time control unit that divides a period into at least two periods of a first period and a second period and controls a time length of at least one of the divided periods according to an output signal of the detection unit; A charge holding element is provided for each light receiving element of the light receiving unit and holds charges accumulated in each light receiving element. The charge holding means transfers the charge accumulated in the light receiving element of the light receiving portion during the first period at the first timing after the end of the first period to the charge holding means and holds the charge at the second timing. Of the charges held in the charge holding means, the charges accumulated in the odd-numbered light receiving elements In the vertical transfer section Of the charges held in the charge holding means at the third timing and accumulated in the even-numbered light receiving elements. In the vertical transfer section The charge accumulated in the light receiving elements in the odd rows of the light receiving unit during the second period at the fourth timing after the end of the second period. In the vertical transfer section The charge accumulated in the light receiving elements in the even-numbered rows of the light receiving unit during the second period at the fifth timing is transferred. In the vertical transfer section Control means for transferring.
[0019]
Further, in the imaging method of the solid-state imaging device according to the present invention, charges are accumulated in the light receiving element according to the amount of incident light from the imaging object during the charge accumulation period, and accumulated. Transfer charge to vertical transfer section , An imaging method of a solid-state imaging device that outputs as an image signal, wherein the charge accumulation period is divided into at least two periods of a first period and a second period, and among the divided periods according to the incident light amount, Control the duration of at least one period Then, the charge accumulated in the light receiving element at the first timing after the end of the first period is held in the charge holding means including charge holding elements provided for each of the light receiving elements, and the charge is held at the second timing. The transferred charge is transferred to the vertical transfer unit, and the charge accumulated in the light receiving element is transferred to the vertical transfer unit at the third timing after the end of the second period. To do.
[0020]
Further, according to the imaging method of the solid-state imaging device of the present invention, the plurality of light receiving elements arranged in a matrix form accumulates charges according to the amount of incident light from the imaging target during the charge accumulation period, and the accumulated charges are received by the light receiving device. Arranged for each row of elements Vertical transfer section By the above matrix Column direction Forward to Above vertical transfer unit The solid-state imaging device image pickup method for transferring the electric charge sent by the horizontal transfer element in the row direction of the matrix and outputting it as a time-series image signal, wherein the charge accumulation period is at least the first period and the second period. The period is divided into two periods, and the time length of at least one of the divided periods is controlled according to the image signal, and stored in the light receiving element at the first timing after the end of the first period. Charge In charge holding means comprising charge holding elements provided for each of the light receiving elements Of the charges held at the second timing and stored in the odd-numbered light receiving elements. Above vertical transfer unit Of the charges held at the third timing and accumulated in the even-numbered light receiving elements. Vertical transfer section The charge accumulated in the odd-numbered light receiving elements at the fourth timing after the end of the second period is transferred to Above vertical transfer unit The charge accumulated in the light receiving elements in the even rows at the fifth timing is transferred to Above vertical transfer unit Forward to.
[0021]
According to the present invention, the imaging period of the solid-state imaging device is divided into a plurality of, for example, at least two periods, and the exposure time of at least one period among the plurality of periods divided according to the amount of incident light is controlled. Therefore, the sensitivity ratio of the exposure period divided into a plurality of amounts according to the amount of incident light from the subject, the imaging conditions, the imaging purpose, etc. can be set arbitrarily, and the dynamic range of the solid-state imaging device can be optimized.
[0022]
Specifically, for example, a light receiving unit comprising light receiving elements arranged for each pixel and arranged in a matrix, a vertical transfer register for vertically transferring and mixing signal charges accumulated in the light receiving elements during the exposure period, and a vertical transfer register A detector for detecting the luminance signal of the image signal output from the horizontal transfer register is added to the solid-state imaging device composed of a horizontal transfer register for transferring the signal charge transmitted from the horizontal direction to the detection result of the detector. By controlling the exposure period in at least one of the plurality of periods divided accordingly, the sensitivity ratio of each exposure period can be set, and the dynamic range of the solid-state imaging device can be optimized.
[0023]
Further, in order to freely set the exposure times of the plurality of divided periods, the solid-state imaging device is provided with a charge holding element that temporarily holds the accumulated charge of each light receiving element for each light receiving element of each light receiving unit. Yes. For example, as an example, when the charge accumulation time is divided into a first period and a second period, all signal charges accumulated in each light receiving element at the first timing after the end of the first period are transferred to the charge holding element. Is done. Then, at the second timing and the third timing after the completion of the vertical transfer of one field in the vertical transfer register, the odd-numbered and even-numbered rows of stored charges in the charge holding element are sequentially transferred to the vertical transfer register. Mixed in the transfer register. Further, at the fourth and fifth timings after the end of the second period, the signal charges accumulated in the light receiving elements in the odd and even rows are sequentially transferred to the vertical transfer register, mixed in the vertical transfer register, and then the horizontal register. And is output as a time-series image signal by the horizontal transfer register.
The exposure times for the plurality of periods thus divided can be arbitrarily set, the incident light amount-sensitivity characteristic of the solid-state imaging device can be arbitrarily set, and the dynamic range can be optimized.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a circuit diagram showing an embodiment of a solid-state imaging device according to the present invention.
As shown in the figure, the solid-state imaging device of this example includes an objective lens 10, an optical filter 20, a solid-state imaging device 30a, a signal processing circuit 40, a drive circuit 50, a timing generation circuit 60a, a synchronization signal generation circuit 70, a luminance signal. A detection circuit 80 and an arithmetic circuit 90 are included.
[0025]
Compared with the conventional solid-state imaging device shown in FIG. 7, the solid-state imaging device of this embodiment is configured by substantially the same circuit except for the solid-state imaging device 30a and the timing generation circuit 60a.
However, in the present invention, the exposure time in at least one of the plurality of periods divided from the charge accumulation period can be arbitrarily set by devising the configuration and operation timing of the solid-state imaging device 30a. As a result, the sensitivity characteristic of each exposure period in the solid-state imaging device can be freely set, the deterioration of the light quantity-sensitivity characteristic in the high luminance region can be avoided, and the dynamic range can be optimized. Further, in order to control the operation timing of the improved solid-state imaging device 30a, the timing generation circuit 60a is changed accordingly.
[0026]
In the solid-state imaging device shown in FIG. 1, the synchronization signal generation circuit 70 generates a horizontal synchronization signal HD and a vertical synchronization signal VD. The timing generation circuit 60a operates in synchronization with the horizontal synchronization signal HD and the vertical synchronization signal VD from the synchronization signal generation circuit 70, and generates a drive pulse signal S60a that controls the operation timing of the entire solid-state imaging device. The drive circuit 50 receives the drive pulse signal S60a from the timing generation circuit 60. Current amplification Then, it inputs into the solid-state image sensor 30a.
[0027]
Incident light from the imaging object is irradiated to the solid-state imaging device 30a through the objective lens 10 and the optical filter 20. The solid-state imaging device 30a generates an image signal S30a according to the amount of incident light at a timing set by the drive pulse signal S50 amplified by the drive circuit 50, and outputs the image signal S30a to the signal processing circuit 40. The signal processing circuit 40 is a solid-state image sensor. 30a Is processed, and the horizontal synchronizing signal HD and the vertical synchronizing signal VD from the synchronizing signal generating circuit 70 are added to the video signal S. _VD0 Output as.
[0028]
The luminance signal detection circuit 80 receives the luminance signal S40 being processed in the signal processing circuit 40, detects it, and outputs a detection signal S80.
The arithmetic circuit 90 receives the detection signal S80 from the luminance signal detection circuit 80, and determines the brightness, contrast, and backlight state of the image based on the detection signal S80. A control signal S90 for performing shutter speed control, objective iris mechanical iris control, or AGC gain control is generated according to the determination result, and supplied to the objective lens 10, the timing generation circuit 60a, and the signal processing circuit 40, respectively, for feedback. To perform exposure control.
[0029]
FIG. 2 is a layout diagram showing the internal configuration of the solid-state imaging device 30a in the present embodiment. As illustrated, the solid-state imaging device 30a includes a plurality of (for example, (m × n)) light receiving elements PD arranged in a matrix. _1,1 , PD _1,2 , ..., PD _{1, n} , PD _2,1 , PD _2,2 , ..., PD _3,1 , PD _3,2 , ..., PD _{m, 1} , PD _{m, 2} ..., PD _{m, n} And a charge holding element CR for each light receiving element in the light receiving part. _1,1 , CR _1,2 , ..., CR _{1, n} , CR _2,1 , CR _2,2 , ..., CR _3,1 , CR _3,2 , ..., CR _{m, 1} , CR _{m, 2} , ..., CR _{m, n} As a result, the solid-state imaging device of this embodiment has a charge holding function for holding the accumulated charges of the respective light receiving elements. Further, similarly to the conventional solid-state imaging device shown in FIG. 7, the vertical transfer unit 32 is formed of transfer elements provided for each column of the light receiving elements in the column direction of the light receiving units, and sent from the vertical transfer unit. A horizontal transfer unit 34 composed of transfer elements that transfer incoming charges in the row direction, a charge detection amplifier 36 that detects the presence or absence of charges, and an output amplifier that outputs a signal from the charge detection amplifier 36. 38 are provided.
[0030]
Light receiving element PD _1,1 , PD _1,2 , PD _1,3 , ..., PD _{1, n} , PD _2,1 , ..., PD _3,1 , ..., PD _{m, 1} ..., PD _{m, n} Is constituted by an optical sensor such as a photodiode that accumulates a predetermined amount of electric charge according to the amount of light incident during the exposure period. Charge retention element CR _1,1 , CR _1,2 , ..., CR _{1, n} , CR _2,1 , CR _2,2 , ..., CR _3,1 , CR _3,2 , ..., CR _{m, 1} , CR _{m, 2} , ..., CR _{m, n} Consists of a charge holding element that temporarily holds the charge accumulated in the light receiving element, and can be constituted by a resistor or a capacitor, for example.
[0031]
The vertical transfer unit 32 has, for example, n columns of transfer elements 32 arranged in the column direction of the matrix in accordance with the columns of light receiving elements arranged in a matrix. _-1 , 32 _-2 , ..., 32 _-n The transfer element is constituted by a register, for example.
The horizontal transfer unit 34 is composed of a horizontal transfer element that transfers the charges sent from the vertical transfer unit in the horizontal direction (the row direction of the matrix formed by the light receiving elements). Note that the horizontal transfer element is configured by, for example, a register, like the vertical transfer element.
[0032]
FIG. 3 is a waveform diagram showing the operation timing of the solid-state imaging device 30a of the present embodiment, and FIG. 4 is a conceptual diagram showing charge accumulation and charge transfer operations in the solid-state imaging device 30a. Hereinafter, the charge accumulation and transfer operations of the solid-state imaging device of the present embodiment will be described with reference to these drawings.
As shown in FIG. 3, the charge accumulation period in the solid-state imaging device 30a of this embodiment is divided into two periods, that is, an exposure period A1 and an exposure period B1. The exposure period A1 and the exposure period B1 are arbitrarily distributed between the normal operation period and the vertical blanking period.
Of the exposure periods A1 and B1, at least one exposure period, for example, the exposure period A1 can be set according to the control signal S90 from the arithmetic circuit 90 shown in FIG. The incident light quantity-sensitivity characteristic during the period can be set arbitrarily, and the sensitivity ratio during each exposure period can be set freely.
[0033]
Hereinafter, the operation of the solid-state imaging device 30a will be described in the order of the exposure periods A1 and B1.
The charge accumulated in each light receiving element during the exposure period A1 is time T. _RO1 Each light receiving element PD at the timing of _1,1 , PD _1,2 , ..., PD _{1, n} , PD _2,1 , PD _2,2 , ..., PD _3,1 , PD _3,2 , ..., PD _{m, 1} , PD _{m, 2} ..., PD _{m, n} To charge holding elements CR provided according to the respective light receiving elements _1,1 , CR _1,2 , ..., CR _{1, n} , CR _2,1 , CR _2,2 , ..., CR _3,1 , CR _3,2 , ..., CR _{m, 1} , CR _{m, 2} , ..., CR _{m, n} Is read out. Note that since this read operation does not affect the signal charge in the vertical transfer register, it can be performed at an arbitrary timing regardless of whether or not the vertical transfer is completed. In addition, the light receiving element which becomes empty immediately after reading starts the next accumulation operation.
[0034]
FIG. 4 shows a light receiving element PD in the solid-state imaging element 30a. _{1, i} , PD _{2, i} , ..., PD _{m, i} A row of light receiving elements, charge holding elements CR _{1, i} , CR _{2, i} , ..., CR _{m, i} One row of charge holding elements and vertical transfer register 30 _-i FIG. 2 illustrates the charge storage and transfer operations of the first embodiment.
FIG. 5A shows an example of a light receiving element PD. _{1, i} , PD _{2, i} , ..., PD _{m, i} To charge holding element CR _{1, i} , CR _{2, i} , ..., CR _{m, i} Fig. 9 shows how signal charges are transferred.
[0035]
Next, after the vertical transfer of the signal charge in the previous field is completed, a time T shown in FIG. _RO2 At the timing, signal charges accumulated in the exposure period A1 are read out to the vertical register by the odd-numbered light receiving elements among the charge holding elements.
As shown in FIG. 4B, the light receiving element PD _{1, i} , PD _{3, i} Charge holding elements CR corresponding to light receiving elements in odd rows such as. _{1, i} , CR _{3, i} ,... Are respectively transferred to the vertical transfer register 32. _-i Forwarded to
[0036]
Next, in the vertical transfer unit, after performing vertical transfer for one line, time T _RO3 At the timing, signal charges accumulated in the exposure period A1 are read out to the vertical register by the light receiving elements in the even rows among the charge holding elements.
As shown in FIG. 4C, the light receiving element PD _{2, i} , PD _{4, i} Charge holding elements CR corresponding to light receiving elements in even rows such as _{2, i} , CR _{4, i} ,... Are respectively transferred to the vertical transfer register 32. _-i Forwarded to
Thus, the signal charges of the odd-numbered and even-numbered light receiving elements accumulated in the same exposure period A1 are mixed in the vertical transfer register.
[0037]
Next, among the charges accumulated during the exposure period B1, the accumulated charges of the light receiving elements corresponding to the odd-numbered rows are equal to the time T. _RO4 This timing is read from each light receiving element to a vertical transfer register provided in accordance with each light receiving element. Then, after performing vertical transfer for one line in the vertical transfer unit, time T _RO5 Among the charges accumulated during the exposure period B1 at this timing, the accumulated charges of the light receiving elements corresponding to even rows are read from the respective light receiving elements to the vertical transfer register.
As a result, the signal charges of the odd-numbered and even-numbered light receiving elements accumulated in the same exposure period B1 are mixed in the vertical transfer register.
[0038]
As shown in FIG. 4D, the light receiving element PD _{1, i} , PD _{3, i} ,..., Etc., the signal charges accumulated in the odd-numbered light receiving elements are respectively transferred to the vertical transfer registers 32 _-i Forwarded to As shown in FIG. 4E, the light receiving element PD _{2, i} , PD _{4, i} The signal charges accumulated in the light receiving elements in even rows such as _-i To the vertical transfer register 32 _-i , The odd-numbered light receiving elements PD sent by the vertical transfer _{1, i} , PD _{3, i} , ... are mixed with the accumulated signal charges.
[0039]
Through the series of operations described above, the charges accumulated in the exposure period A1 and the charges accumulated in the exposure period B1 are alternately held in the vertical transfer register. After the reading is completed, the signal charges accumulated in the exposure period A1 and the exposure period B1 are transferred to the charge detection amplifier 36 in time series by vertical transfer, vertical register-horizontal register transfer, and horizontal transfer. The result is amplified by the output amplifier 38 and output as the image signal S30a.
[0040]
As described above, the signal charges in the exposure periods A1 and B1 have the light quantity-sensitivity characteristics shown in FIGS. 5A and 5B with respect to the input light quantity due to the difference in the exposure periods. Then, the signal processing circuit 40 provided at the subsequent stage of the solid-state imaging device 30a performs addition / correction processing on these signals, and the light quantity-sensitivity shown in FIG. Characteristics can be obtained.
That is, since the exposure period A1 and the exposure period B1 can be arbitrarily set, as shown in FIGS. 5A and 5B, the slope of the sensitivity characteristic corresponding to each exposure period can be arbitrarily controlled. Accordingly, the light amount-sensitivity characteristics of the entire solid-state imaging device can be arbitrarily set as shown in FIG. 5C, and dynamic range optimization control can be realized.
[0041]
In the solid-state imaging device of this embodiment shown in FIG. 1, the luminance signal S40 from the signal processing circuit 40 is subjected to processing such as integration processing and peak detection in the luminance signal detection circuit 80, and the detection signal from the luminance signal detection circuit 80 is detected. In S80, the arithmetic circuit 90 determines the brightness and contrast of the image, the backlight state, and the like. A control signal S90 for performing electronic shutter speed control, mechanical iris control of the objective lens 10, or AGC gain control is generated for the image state determined by the arithmetic circuit 90. By feeding back to the circuit 60a and the signal processing circuit 40, the respective controls are automatically performed according to the imaging conditions and the imaging purpose.
[0042]
In the solid-state imaging device of the present embodiment having such characteristics, the exposure period A1 and the exposure are determined by the detection signal S80 from the detection circuit 80 and the control signal S90 generated according to the result of the arithmetic processing performed on the arithmetic circuit 90 based on the detection signal S80. The sensitivity ratio of the period B1 can be arbitrarily set, and the dynamic range of the solid-state imaging device can be optimized according to the imaging situation and the imaging purpose.
For example, when the image contrast is small and dark overall as shown in FIG. 6A, the exposure setting is set only for the exposure period A1, or the image contrast is small but overall bright as shown in FIG. 6B. In the state, it is possible to make the sensitivity ratio of the exposure period A1 and the exposure period B1 the same or use a signal of only the exposure period A1 (or only B1). On the contrary, as shown in FIG. 5C, when the contrast of the image is large, the dynamic range of the image can be improved by increasing the sensitivity ratio between the exposure period A1 and the exposure period B1, and according to the degree of contrast. It is also effective to change the sensitivity ratio between the exposure period A1 and the exposure period B1.
[0043]
As described above, according to the present embodiment, incident light is applied to the solid-state imaging device 30a through the objective lens 10 and the optical filter 20, and the solid-state imaging device 30a divides the exposure period into a plurality of periods and accumulates them in each period. An image signal S30a corresponding to the signal charge is generated and input to the signal processing circuit 40. The horizontal and vertical synchronization signals HD and VD generated by the synchronization signal generation circuit 70 are supplied to the timing generation circuit 60a and the signal processing circuit 40, respectively. 60a Responded accordingly Synchronous drive pulse signal S60a is generated and amplified by the drive circuit 50 and then input to the solid-state imaging device 30a to control its operation timing. _VD0 Is output. The luminance signal detection circuit 80 detects the luminance signal S40 from the signal processing circuit 40 and outputs the detection signal S80, and the arithmetic circuit 90 performs arithmetic processing on the detection signal S80 to determine the brightness, contrast, and backlight state of the image. The control signal S90 is generated and the objective lens 10 Since feedback control is performed by feeding back to the timing generation circuit 60a and the signal processing circuit 40, optimization of the dynamic range can be realized according to the imaging state.
[0045]
【The invention's effect】
As described above, according to the solid-state imaging device and the method thereof according to the present invention, by arbitrarily setting the sensitivity ratio of the exposure period divided into a plurality according to the determination result of the image state, Since the balance of the light quantity-sensitivity characteristics in the high luminance region can be set freely, there is an advantage that the dynamic range of the image pickup apparatus can be optimized according to the state of the subject such as the backlight state or the contrast.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of a solid-state imaging device according to the present invention.
FIG. 2 is a layout diagram showing an internal configuration of a solid-state imaging device according to the present invention.
FIG. 3 is a waveform diagram showing operation timings of the solid-state imaging device according to the present invention.
FIG. 4 is a conceptual diagram showing charge accumulation and charge transfer operations in the solid-state imaging device according to the present invention.
FIG. 5 is a graph showing light quantity-sensitivity characteristics of the solid-state imaging device of the present invention.
FIG. 6 is a conceptual diagram illustrating a situation of brightness and contrast of a subject.
FIG. 7 is a block diagram illustrating an example of a conventional solid-state imaging device.
FIG. 8 is a layout diagram showing the internal configuration of a conventional solid-state image sensor.
FIG. 9 is a waveform diagram showing the operation timing of a conventional solid-state imaging device.
FIG. 10 is a conceptual diagram showing charge accumulation and charge transfer operations in a conventional solid-state imaging device.
FIG. 11 is a graph showing light quantity-sensitivity characteristics of a conventional solid-state imaging device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Objective lens, 20 ... Optical filter, 30, 30a ... Solid-state image sensor, 40 ... Signal processing circuit, 50 ... Drive circuit, 60, 60a ... Timing generation circuit, 70 ... Synchronization signal generation circuit, 80 ... Luminance signal detection circuit , 90 ... arithmetic circuit, PD _1,1 , PD _1,2 , ..., PD _{1, n} , PD _2,1 , PD _2,2 , ..., PD _3,1 , PD _3,2 , ..., PD _{m, 1} , PD _{m, 2} ..., PD _{m, n} ... Light receiving element, CR _1,1 , CR _1,2 , ..., CR _{1, n} , CR _2,1 , CR _2,2 , ..., CR _3,1 , CR _3,2 , ..., CR _{m, 1} , CR _{m, 2} , ..., CR _{m, n} ... Charge holding element, 32 ... Vertical transfer unit, 32 _-1 , 32 _-2 , ..., 32 _-n ... vertical transfer register, 34 ... horizontal transfer, 36 ... charge detection amplifier, 38 ... output amplifier.

Claims

A solid-state imaging device that transfers charges accumulated in a light receiving element in response to incident light from an imaging object during a charge accumulation period via a transfer unit, and outputs the image signal as an image signal,
A control means for dividing the charge accumulation period into at least two periods of a first period and a second period, and controlling a time length of at least one of the divided periods according to the amount of incident light ;
Charge holding means provided for each of the light receiving elements, comprising charge holding elements for holding charges accumulated in the respective light receiving elements;
The charge accumulated in the light receiving element at the first timing after the end of the first period is transferred and held in the charge holding means, the charge held in the charge holding means is transferred at the second timing, and A solid-state imaging device comprising: transfer control means for transferring and outputting the charge accumulated in the light receiving element during the second period at a third timing after the end of the second period .

Having detection means for detecting the image signal,
The solid-state imaging device according to claim 1, wherein the control unit controls a time length of at least one of the divided periods according to an output signal of the detection unit.

A light receiving portion that is provided for each pixel and includes a plurality of light receiving elements arranged in a matrix;
A vertical transfer unit arranged in the column direction for each light receiving element row of the light receiving unit and transferring the charge accumulated in the light receiving element in the column direction according to the amount of incident light from the imaging target during the charge accumulation period;
A horizontal transfer unit composed of transfer elements that transfer the electric charge sent from the vertical transfer unit in the row direction and output it as a time-series image signal;
Detection means for detecting the image signal output by the horizontal transfer unit;
An exposure time control that divides the charge accumulation period into at least two periods of a first period and a second period, and controls the time length of at least one of the divided periods according to the output signal of the detection means. Means,
A charge holding unit that is provided for each light receiving element of the light receiving unit and includes a charge holding element that holds charges accumulated in each light receiving element ;
At a first timing after the end of the first period, the charge accumulated in the light receiving element of the light receiving section during the first period is transferred to the charge holding means and held at the second timing. Transfer to the vertical transfer unit, and transfer the charge accumulated in the light receiving element of the light receiving unit during the second period to the vertical transfer unit at a third timing after the end of the second period. And a solid-state imaging device.

4. The solid-state imaging device according to claim 3 , wherein the second timing is set after the transfer of accumulated charges corresponding to the image signal of the previous field to the vertical transfer unit. 5.

The solid-state imaging according to claim 3 , wherein after the charge accumulated in the light receiving element of the light receiving unit at the first timing is transferred to the charge holding means, the charge of each light receiving element is cleared and a next charge accumulation period starts. apparatus.

A light receiving portion that is provided for each pixel and includes a plurality of light receiving elements arranged in a matrix;
A vertical transfer unit arranged in the column direction for each light receiving element row of the light receiving unit and transferring the charge accumulated in the light receiving element in the column direction according to the amount of incident light from the imaging target during the charge accumulation period;
A horizontal transfer unit composed of transfer elements that transfer the electric charge sent from the vertical transfer unit in the row direction and output it as a time-series pixel signal;
Detection means for detecting the pixel signal output by the horizontal transfer unit;
An exposure time control that divides the charge accumulation period into at least two periods of a first period and a second period, and controls the time length of at least one of the divided periods according to the output signal of the detection means. Means,
A charge holding unit that is provided for each light receiving element of the light receiving unit and includes a charge holding element that holds charges accumulated in each light receiving element ;
At a first timing after the end of the first period, the charge accumulated in the light receiving element of the light receiving section during the first period is transferred to the charge holding means and held at the second timing. The charges accumulated in the odd-numbered rows of light receiving elements are transferred to the vertical transfer unit, and the charges held in the charge holding means at the third timing are accumulated in the even-numbered rows of light receiving elements. the charge transferred to the vertical transfer section, a charge accumulated in the light receiving elements of the odd rows of the light receiving portion during the second period in the fourth timing after completion of the second period is transferred to the vertical transfer section And a control means for transferring the charges accumulated in the light receiving elements in the even-numbered rows of the light receiving section to the vertical transfer section during the second period at the fifth timing.

The solid-state imaging according to claim 6 , wherein after the charge accumulated in the light receiving element of the light receiving unit at the first timing is transferred to the charge holding unit, the charge of each light receiving element is cleared and a next charge accumulation period starts. apparatus.

After charges accumulated in the light receiving elements of the odd rows stored in the charge holding means in the second timing is transferred to the vertical transfer unit, according to claim 6, wherein a single transfer operation in the vertical transfer portion is performed Solid-state imaging device.

After the transfer operation is performed, the accumulated charge of the odd-numbered light receiving elements held in the vertical transfer unit is transferred from the charge holding means at the third timing, and the accumulated charge of the even-numbered light receiving elements. The solid-state imaging device according to claim 8 , wherein the solid-state imaging device is mixed.

The solid-state imaging device according to claim 6, wherein after the accumulated charges of the odd-numbered light receiving elements are transferred to the vertical transfer unit at the fourth timing, a single transfer operation is performed in the vertical transfer unit.

After the transfer operation is performed, the accumulated charges of the odd-numbered light receiving elements held in the vertical transfer unit are mixed with the accumulated charges sent from the even-numbered light receiving elements at the fifth timing. The solid-state imaging device according to claim 10 .

An imaging method for a solid-state imaging device that accumulates charges in a light receiving element according to the amount of incident light from an imaging target during a charge accumulation period, transfers the accumulated charges to a vertical transfer unit, and outputs the image signals as an image signal,
Dividing the charge accumulation period into at least two periods of a first period and a second period, and controlling a time length of at least one of the divided periods according to the incident light amount ;
The charge accumulated in the light receiving element at the first timing after the end of the first period is held in a charge holding unit including a charge holding element provided for each of the light receiving elements,
Transferring the held charges to the vertical transfer unit at a second timing;
An imaging method of a solid-state imaging device, wherein charges accumulated in the light receiving element at a third timing after the end of the second period are transferred to the vertical transfer unit .

A plurality of light receiving elements arranged in a matrix form accumulates charges according to the amount of incident light from the imaging target during the charge accumulation period, and the accumulated charges are transferred by the vertical transfer unit arranged for each row of the light receiving elements. transferred in the column direction of the matrix, an imaging method of a solid-state imaging device by the horizontal transfer device charges sent by the vertical transfer unit to transfer in the row direction of the matrix, and outputs as an image signal of the time series,
The charge accumulation period is divided into at least two periods of a first period and a second period, and the time length of at least one of the divided periods is controlled according to the image signal, and the end of the first period The charge accumulated in the light receiving element at a later first timing is held in a charge holding means including a charge holding element provided for each of the light receiving elements ,
Transferring the held charges to the vertical transfer unit at a second timing;
An imaging method of a solid-state imaging device, wherein charges accumulated in the light receiving element at a third timing after the end of the second period are transferred to the vertical transfer unit .

14. The solid-state imaging device according to claim 13 , wherein after the charge accumulated in the light receiving element at the first timing is transferred to the charge holding means, the charge in the light receiving element is cleared and a next charge accumulation period is started. Method.

The imaging method of the solid-state imaging device according to claim 13 , wherein the second timing is set after the transfer of the accumulated charge corresponding to the image of the previous field is completed in the vertical transfer unit .

A plurality of light receiving elements arranged in a matrix form accumulates charges according to the amount of incident light from the imaging target during the charge accumulation period, and the accumulated charges are transferred by the vertical transfer unit arranged for each row of the light receiving elements. transferred in the column direction of the matrix, an imaging method of a solid-state imaging device by the horizontal transfer device charges sent by the vertical transfer unit to transfer in the row direction of the matrix, and outputs as an image signal of the time series,
The charge accumulation period is divided into at least two periods of a first period and a second period, and the time length of at least one of the divided periods is controlled according to the image signal, and the end of the first period The charge accumulated in the light receiving element at a later first timing is held in a charge holding means including a charge holding element provided for each of the light receiving elements ,
Of the charges held at the second timing, charges accumulated by the odd-numbered light receiving elements are transferred to the vertical transfer unit , and among the charges held at the third timing, the even-numbered light receiving elements. the accumulated charge is transferred to the upper Symbol vertical transfer section, a charge accumulated in the light receiving elements of the odd rows in the fourth timing after completion of the second period is transferred to the vertical transfer unit, even rows in the fifth timing An image pickup method for a solid-state image pickup device, wherein charges accumulated in the light receiving element are transferred to the vertical transfer unit .

17. The solid-state imaging device according to claim 16 , wherein after the charge accumulated in the light receiving element at the first timing is transferred to the charge holding unit, the charge in the light receiving element is cleared and a next charge accumulation period is started. Method.

The imaging method of the solid-state imaging device according to claim 16 , wherein the second timing is set after the transfer of the accumulated charge corresponding to the image of the previous field to the vertical transfer unit .

After the transfer operation in the second timing, claim performs a single transfer operation by the vertical transfer unit, is mixed with the charge of the transfer unit after the transfer has been sent by the third timing charge 16 An imaging method of the described solid-state imaging device.

After the fourth transfer operation, performed a single transferring operation by the vertical transfer unit, the charge of the transfer portion after the transfer of claim 16 wherein the mixing with the charge sent by the fifth timing An imaging method for a solid-state imaging device.