JP4167452B2 - Image display device - Google Patents

Description

【０１６４】
本実施の形態によれば、データ線毎に細かい遅延量制御が可能であり、より適正な表示位置制御が可能となる。
【０１６５】
本発明の第十二の実施の形態を図２６に基づいて説明する。本実施の形態は、第十の実施の形態の表示データ制御手段９１中に示した遅延回路９４（９４ｒ，９４ｇ，９４ｂ）に代えて、図２６に示すように、フレームバッファ９２からのデータ線毎に遅延素子１１１を経由するデータ線と、遅延素子１１１をバイパスするデータ線とを用意し、制御回路９５からの制御信号に基づき各ライトバルブ５（５ｒ，５ｇ，５ｂ）に対して何れのデータ線によるデータを出力させるかを選択的に切替える接続切替え手段としてのセレクタ１１２を設けた遅延回路１１３として構成されている。遅延素子１１１自体は遅延素子９６と同様の素子を用い得る。また、ライトバルブ５の制御信号数は多いが、図２６では説明を簡単にするため、３本のみを示している。
【０１６６】
このような構成により、遅延を必要とするライトバルブ５はセレクタ１１２を切替えることで、遅延素子１１１を経由した信号を、遅延を必要としないライトバルブ５へはセレクタ１１２を切替えることにより遅延素子１１１を経由しない信号を入力させることができる。
【０１６７】
ちなみに、セレクタ１１２の切替えには、１bitの制御端子を使用し、この制御端子を電源電圧又はＧＮＤレベルに切替えることにより実行される。
【０１６８】
本実施の形態によれば、遅延を必要とするライトバルブ５のみ、セレクタ１１２の切替えのみで、信号を遅延させることができる。
【０１６９】
本発明の第十三の実施の形態を図２７及び図２８に基づいて説明する。本実施の形態は、第十の実施の形態の表示データ制御手段９１の各遅延回路９４ｒ，９４ｇ，９４ｂ中のアナログ制御の遅延素子９６に代えて、デジタル処理により遅延量の制御が可能なデジタル制御遅延素子としてのラッチ１２１ｒ，１２１ｇ，１２１ｂを遅延素子として用いたものである。ラッチ１２１は例えばフリップフロップ構成のもので、基準信号としてのサンプリング信号としてクロック信号が用いられ、データを遅延させる場合にはラッチ１２１を使用することでクロック信号に応じた遅延を発生させることとなる。逆に、他のデータより前にシフトさせたい時には、先に進めたいデータ以外のデータをラッチ１２１により遅延させればよい。
【０１７０】
図２８にラッチ１２１の動作例を示す。遅延させる信号を元信号として示し、当該ラッチ１２１としてはクロックの立上りで動作するフリップフロップが用いられている。ラッチ１２１はクロックの立上りの度にサンプリングされ、遅延信号に示すように元信号に対して遅延が生ずることとなる。
【０１７１】
【実施例】
上述した各実施の形態に準じて構成した幾つかの実施例を以下に列挙する。
【０１７２】
［実施例１］
ライトバルブ５ｒ，５ｇ，５ｂとして強誘電性液晶を用いた画素ピッチ１４μｍ、画素数１０２４×７６８画素の透過型のライトバルブを用い、図１に示すような構成の光学系を有する投射型の画像表示装置を作製した。光源１には１２０Ｗの高圧水銀ランプを使用した。偏光回転素子１３には１／２波長板を用い、緑色光のみｓ偏光でライトバルブ５ｇに入射するように構成した。照明系のＦ値は２．８とした。フライアイレンズ２，３部には偏光変換素子（図示せず）を設け、他の色光はライトバルブ５ｒ，５ｂに対してｐ偏光で入射するように構成した。ライトバルブ５ｒ，５ｇ，５ｂはオン時に入射偏光を９０°回転させるような構成とし、これにより、クロスダイクロイックプリズム７に入射する偏光は緑に対してはｐ、他色光に対してはｓ偏光とした。光路変調手段１４には強誘電性液晶素子からなる偏光変調手段１５とニオブ酸リチウムを結晶軸に対して４５°の方向に切り出した光路偏向素子１６とを組合せて用いた。強誘電性液晶のレターデーションは０．２２μｍとし、コーン角は４５°とした。投射光の偏光方向は強誘電性液晶の一方の双安定配向方向と一致又は直交するように構成し、負電圧印加持には入射偏光を維持し、正電圧印加持には入射偏光の偏光面を９０°回転させるように構成した。これにより、強誘電性液晶素子からなる偏光変調手段１５のスイッチングにより出射光の偏光をｓ偏光とｐ偏光とに切替えるよう構成した。ニオブ酸リチウムの板厚は０．１８ｍｍとし、結晶軸の傾斜方向はｐ偏光の方向とした。画像光は投射レンズ８により拡大投射し、フロントプロジェクション方式の画像表示装置を構成した。
【０１７３】
強誘電性液晶素子からなる偏光変調手段１５は１２０Ｈｚで動作されており、駆動タイミングをずらすことで、２種類のシフト方向の異なる２つのサブフレームを構成した。各々のサブフレーム毎にライトバルブ５ｒ，５ｇ，５ｂの書き込み画像情報及び偏光変調手段１５を制御した。強誘電性液晶素子からなる偏光変調手段１５に負電圧を印加した際には、緑のライトバルブ５ｇには図７（ｃ′）のように偶数ラインの画像情報を、青と赤のライトバルブ５ｂ，５ｒには図７（ａ′）のように奇数ラインの画像情報を書き込んだ。また、強誘電性液晶素子からなる偏光変調手段１５に正の電圧を印加した場合には、逆に、緑のライトバルブ５ｇには奇数ラインの画像情報を、青と赤のライトバルブ５ｂ，５ｒには偶数ラインの画像情報を書き込んだ。
【０１７４】
このような構成の本実施例の画像表示装置を動作させたところ、光路変調手段１４の作用により元画像に対して横半ピッチ分ずれた表示と元画像の表示の間で高速の変調が可能であり、サブフレーム間で画素ずれのない１０２４×１５３６画素なる高解像度の表示を行わせることができたものである。また、画像に色むらはほとんど観測されなかったものである。従って、この画像表示装置による投影画像には色ずれはみられず、良好な表示が行えたものである。
【０１７５】
［実施例２］
実施例１において、照明光の偏光回転用の偏光回転素子１３を用いずに緑のライトバルブ５ｇへの書き込み画像情報のオン・オフを反転させることで、緑色光のみダイクロイックプリズム７に入射する偏光をｐとし、他色に対してはｓ偏光とした。他は実施例１と同様にして光学系を構成し、同様にして動作させた。
【０１７６】
このような構成の本実施例の画像表示装置を動作させたところ、光路変調手段１４の作用により元画像に対して横半ピッチ分ずれた表示と元画像の表示の間で高速の変調が可能であり、サブフレーム間で画素ずれのない１０２４×１５３６画素なる高解像度の表示を行わせることができたものである。また、画像に色むらはほとんど観測されなかったものである。従って、この画像表示装置による投影画像には色ずれはみられず、良好な表示が行えたものである。
【０１７７】
［実施例３］
実施例２において、光路変調手段１４（１４ｘ）の直後に、１／２波長板１７を出射光の偏光面が９０°回転するように設け、さらにその出射側にも光路変調手段１４ｙを設けて図１１のように構成した。光路変調手段１４ｙは、光路変調手段１４ｘと同様に構成したが、光路偏向素子１６ｙとしてのニオブ酸リチウムの結晶軸の傾斜方向を光路偏向素子１６ｘとは直交するように構成した。このような構成により、縦横４方向への光路シフトを可能とした。画像光は投射レンズ８により拡大投射し、フロントプロジェクション方式の画像表示装置を構成した。
【０１７８】
各々の光路変調手段１４ｘ，１４ｙの２つの強誘電性液晶素子による偏光変調手段１５ｘ，１５ｙは、各々１２０Ｈｚで動作しており、駆動タイミングをずらすことで、４種類のシフト方向の異なる４つのサブフレームを構成した。各々のサブフレーム毎にライトバルブ５ｒ，５ｇ，５ｂの書き込み画像情報及び偏光変調手段１５ｘ，１５ｙを制御した。強誘電性液晶に負電圧を印加した際には、緑のライトバルブ５ｇには図７（ｃ′）に示したように偶数ラインの画像情報を、青と赤のライトバルブ５ｂ，５ｒには図７（ａ′）に示したように奇数ラインの画像情報を書き込んだ。また、強誘電性液晶に正の電圧を印加した場合には、緑のライトバルブ５ｇには奇数ラインの画像情報を、青と赤のライトバルブ５ｂ，５ｒには偶数ラインの画像情報を書き込んだ。
【０１７９】
このような構成の本実施例の画像表示装置を動作させたところ、光路変調手段１４ｘ，１４ｙの作用により元画像に対して縦横半ピッチ分ずれた表示と元画像の表示の間で高速の変調が可能であり、サブフレーム間で画素ずれのない２０４８×１６３６画素なる高解像度の表示を行わせることができたものである。また、画像に色むらはほとんど観測されなかったものである。従って、この画像表示装置による投影画像には色ずれはみられず、良好な表示が行えたものである。
【０１８０】
［実施例４］
実施例３において、図１２に示したように緑用のライトバルブ５ｇの画素位置を他のライトバルブ５ｒ，５ｂの画素位置に対して画素の１／２ピッチずらして配置した。各ライトバルブ５ｒ，５ｇ，５ｂに同時に書き込む画素は表示データの偶数ライン又は奇数ラインの何れか一方とした。偏光変調手段１５である強誘電性液晶素子に負電圧を印加した際には、緑のライトバルブ５ｇには光路シフト方向に対して半ピッチずれた画素位置に書き込みを行い（図１２中の画素５ｒｐ１，５ｂｐ１に対する画素５ｇｐ１の位置）、強誘電性液晶素子に正電圧を印加する際には、光路シフト方向と逆方向に半ピッチずれた画素位置（５ｇｐ２）に書き込みを行うように制御した。
【０１８１】
このような書き込み制御により、赤、青と緑の画像光は同じ位置に投射され、偏光変調手段１５である強誘電性液晶素子のスイッチングにより画素の半ピッチに相当するだけシフトする。
【０１８２】
このような構成の本実施例の画像表示装置を動作させたところ、光路変調手段１４の作用により元画像に対して横半ピッチ分ずれた表示と元画像の表示の間で高速の変調が可能であり、サブフレーム間で画素ずれのない１０２４×１５３６画素なる高解像度の表示を行わせることができたものである。また、画像に色むらはほとんど観測されなかったものである。従って、この画像表示装置による投影画像には色ずれはみられず、良好な表示が行えたものである。
【０１８３】
［実施例５］
図１５に示す光学系により投射型の画像表示装置を作製した。照明系には実施例１と同様の光源１及びインテグレータ光学系４を備える照明装置１２を用いた。波長選択性位相差板４３としてはカラーリンク社のgreen／magentaフィルタを用い、緑の偏光のみをｐ偏光に変換した。ライトバルブ３１ｒ，３１ｇ，３１ｂには画素ピッチ１４μｍ、画素数１０２４×７６８画素の反射型のライトバルブを用いた。
【０１８４】
本実施例の構成により、緑用のライトバルブ３１ｇにはｐ偏光が、青、赤用のライトバルブ３１ｂ，３１ｒにはｓ偏光が照明される。ライトバルブ３１ｒ，３１ｇ，３１ｂはオン画素に対応する光を９０°回転させるように作用するので、射出光は緑がｓ偏光、青と赤がｐ偏光として射出される。
【０１８５】
ライトバルブ３１ｒ，３１ｇ，３１ｂに対する画像情報の書き込み方法を実施例１と同様にして本実施例の画像表示装置を動作させたところ、光路変調手段１４の作用により元画像に対して横半ピッチ分ずれた表示と元画像の表示の間で高速の変調が可能であり、画素ずれのない１０２４×１５３６画素なる高解像度の表示を行わせることができたものである。また、画像に色むらはほとんど観測されなかったものである。従って、この画像表示装置による投影画像には色ずれはみられず、良好な表示が行えたものである。
【０１８６】
［実施例６］
実施例５において、緑のライトバルブ３１ｇの画素位置を他のライトバルブ３１ｒ，３１ｂの画素位置に対して半ピッチずらして配置し、動作方法については実施例４と同様に動作させた。
【０１８７】
本実施例の画像表示装置は、光路変調手段１４の作用により元画像に対して横半ピッチ分ずれた表示と元画像の表示の間で高速の変調が可能であり、画素ずれのない１０２４×１５３６画素なる高解像度の表示を行わせることができたものである。また、画像に色むらはほとんど観測されなかったものである。従って、この画像表示装置による投影画像には色ずれはみられず、良好な表示が行えたものである。
【０１８８】
【発明の効果】
請求項１記載の発明によれば、色合成手段に入射する複数の画像光のうち少なくとも１色の偏光状態が他の色光の偏光状態と異なることにより、色合成手段の入射角依存性に起因する表示むらを抑え、又は、高効率な色合成を行わせることができる画像表示装置において、合成された画像光の光路を変調する光路変調手段を備えるとともに、画像フレーム期間に各ライトバルブに書き込む表示画像として、当該画像フレーム期間の光路変調手段の作動状態による偏光状態に応じた光路シフト量に対応した表示位置の画像情報を書き込む構成とすることで、色ずれのない解像度の高い表示を行わせることができる。
【０１８９】
請求項２記載の発明によれば、請求項１記載の画像表示装置において、画像光の偏光状態を直線偏光とし、偏光状態の違いを直交関係とすることで、光路シフト量が明確となり、ライトバルブに対する画像情報の書き込み位置の補正で適正に対処可能となり、光路変調手段によるシフトに伴う画素位置ずれのない高解像度の画像表示が可能となる。
【０１９０】
請求項３記載の発明によれば、請求項１又は２記載の画像表示装置において、画像フレーム期間の光路変調手段の作用状態による偏光状態に応じた光路シフト量に対応した表示位置の画像情報を書き込む構成の具体的な情報書き込み方法が明らかとなり、色ずれのない解像度の高い表示が可能となる。
【０１９１】
請求項４記載の発明によれば、請求項１又は２記載の画像表示装置において、解像度の高い表示に加えて、より簡便な情報書き込み方法で実現可能となる。
【０１９２】
請求項５記載の発明によれば、請求項４記載の画像表示装置において、解像度の高い表示に加えて、より簡便かつ具体的な情報書き込み方法が明らかとなる。
【０１９３】
請求項６記載の発明によれば、請求項４又は５記載の画像表示装置において、ｎ＝０の場合が最も簡便で、周辺部の表示領域を最も有効に活用できる光学的構成及び情報書き込み方法となる。
【０１９４】
請求項７記載の発明によれば、請求項１ないし６の何れか一記載の画像表示装置において、ライトバルブ個別のサブフレームバッファ等の記憶素子を持たずに、データを更新するため、高速応答が必要な記憶素子、制御回路等の部品点数が減り、低コスト化を実現できる。また、各ライトバルブ毎に個別の記憶領域を確保することで、各色個別の制御を容易に行うことができ、制御回路の小型化、部品点数の低減による低コスト化が可能となる。
【０１９５】
請求項８記載の発明によれば、請求項１ないし６の何れか一記載の画像表示装置において、各ライトバルブと１画面の画像情報を記憶する記憶素子との間に転送用記憶手段を設けることで、フレームバッファ等の記憶素子のデータ転送速度を低減し、部品コストの低減と安定動作とが実現される。この際、サブフレーム用のバッファの場合と異なり、ライトバルブの画素数よりも少ない容量の転送用記憶素子を用いて、制御信号の期間をも使用して低速化を図っているため、部品コストの低減とともに安定した動作が確保される。
【０１９６】
請求項９記載の発明によれば、請求項３記載の画像表示装置を実現する上で、予め画像情報の読み出し方法を２種類以上規定して読み出し方法保持手段に設定保持させておき、その読み出し方法を光路変調手段の第１，第２の作用状態の切替えに対応させて切替えることで、記憶素子からの画像シフト対応の画像情報の読み出しが可能なため、新規に演算することなく、回路の小型化と部品コストの低減とが可能となる。
【０１９７】
請求項１０記載の発明によれば、請求項５記載の発明を実現する上で、記憶素子は必要な画像情報量に応じた記憶容量を準備することで、記憶容量を無駄なく必要最低限の容量で構成することが可能となる。
【０１９８】
請求項１１記載の発明によれば、請求項１ないし６の何れか一記載の画像表示装置において、個々のライトバルブ自体に入力された画像情報のデータの転送タイミングを調整する機能を持たせた表示データ制御手段を実装することで、既存の記憶素子やその制御回路を使用したままでライトバルブに対して画像情報のデータを入力させることができ、周辺回路等の部品コストを削減することができる。
【０１９９】
請求項１２記載の発明によれば、請求項１ないし６の何れか一記載の画像表示装置において、ライトバルブの入力端子と記憶素子の出力端子との間にデータの転送タイミングの調整自在なタイミング制御手段を備えることで、既存のライトバルブ及び従来からの画像情報のシフトを考慮しない記憶素子の制御構成を使用したまま、画像情報のシフトを実現することで、新規な構成の付加を最低限として、低コスト化を実現することができる。
【０２００】
請求項１３記載の発明によれば、タイミング制御手段について遅延素子を用いることにより、請求項１２記載の画像表示装置を容易に実現することができる。
【０２０１】
請求項１４記載の発明によれば、請求項１２記載の画像表示装置を実現する上で、遅延量の多段階制御が可能となり、適正な表示位置制御を行わせることができる。
【０２０２】
請求項１５記載の発明によれば、請求項１２記載の画像表示装置を実現する上で、遅延を必要とするライトバルブのみ、接続切替え手段の切替えのみで、信号を遅延させることができる。
【０２０３】
請求項１６記載の発明によれば、請求項１３ないし１５の何れか一記載の画像表示装置を実現する上で、温度、設定時のバラツキ等に対しても安定で、再調整が不要なため、制御性に優れた遅延制御が可能となる。
【０２０４】
請求項１７記載の発明によれば、請求項１ないし１６の何れか一記載の画像表示装置において、色合成手段の好適例を提供することができる。特に、ダイクロイックプリズムを用いた場合には、照明光の入射角特性によって、合成光の波長シフトが生じ、それに伴って表示に色むらを生じやすいが、色合成手段に入射する複数の画像光のうち少なくとも１色の偏光状態を他の色光の偏光状態と異ならせることにより、色合成手段の入射角依存性に起因する表示むらを抑えるとともに、高効率の色合成を行わせることができ、さらに、画像フレーム期間に各ライトバルブに書き込まれる画像情報は、当該画像フレーム期間の光路変調手段の作動状態による偏光状態に応じた光路シフト量に対応した表示位置の画像情報を書き込む構成とすることで、色ずれのない解像度の高い表示を行わせることができる。
【０２０５】
請求項１８記載の発明によれば、請求項１７記載の画像表示装置のより具体的な構成例が明らかとなる。
【０２０６】
請求項１９記載の発明によれば、請求項１７又は１８記載の画像表示装置において、色合成手段に入射する複数の画像光のうち少なくとも１色の偏光状態が他の色光の偏光状態と異なるようにする具体例を提供することができる。
【０２０７】
請求項２０記載の発明によれば、請求項１７又は１８記載の画像表示装置において、色合成手段に入射する複数の画像光のうち少なくとも１色の偏光状態が他の色光の偏光状態と異なるようにする簡便で効率的な具体例を提供することができる。
【０２０８】
請求項２１記載の発明によれば、請求項１ないし１６の何れか一記載の画像表示装置において、色合成手段の好適例を提供することができる。特に、偏光ビームスプリッタでの合成では、合成光の偏光状態は異なる２種の偏光が混在するが、画像フレーム期間の光路変調手段の作動状態による偏光状態に応じた光路シフト量に対応した表示位置の画像情報を書き込む構成とすることで光路変調手段を設けた場合においても色による画素ずれのない、解像度の高い表示を行わせることができる。
【０２０９】
請求項２２記載の発明によれば、請求項２１記載の発明を実現する上で、小型で、高効率な光学系構成を提供することができる。
【０２１１】
請求項２３記載の発明によれば、請求項１記載の発明を実現する上で、光路偏向素子の好適例を提供することができる。
【０２１２】
請求項２４記載の発明によれば、請求項２３記載の画像表示装置において、応答速度の速い強誘電性液晶による液晶素子を用いることで、入射偏光を高速で偏光面の直交する２つの偏光状態に切替える動作を応答性よく実現することができる。
【０２１３】
請求項２５記載の発明によれば、請求項２３又は２４記載の画像表示装置において、一軸性光学異方体として安定性、コスト、透明性に優れたニオブ酸リチウム結晶を用いることで、好適な構成例を提供することができる。
【０２１４】
請求項２６記載の発明によれば、請求項１ないし２５の何れか一記載の画像表示装置において、２次元に光路変調を行うことができるため、さらに高い解像度を得ることができる。
【０２１５】
請求項２７記載の発明によれば、請求項１ないし２６の何れか一記載の画像表示装置において、ライトバルブとしてデジタル的に動作する強誘電性液晶による液晶表示素子を用いることにより、好適な構成例を提供することができる。
【０２１６】
請求項２８記載の発明によれば、請求項１ないし２６の何れか一記載の画像表示装置において、ライトバルブとして応答速度に優れた反強誘電性液晶による液晶表示素子を用いることにより、中間調表現に適した好適な構成例を提供することができる。
【図面の簡単な説明】
【図１】本発明の第一の実施の形態の画像表示装置全体の光学系構成を示す構成図である。
【図２】光路変調手段の原理的構成例及びその作用を説明するための側面図である。
【図３】光路変調手段の作用を説明するために画像情報及び表示画像を示す模式図である。
【図４】単なる光路シフトによる欠点を説明するために画像情報及び表示画像を示す模式図である。
【図５】その合成画像の表示例を示す模式図である。
【図６】本実施の形態のライトバルブに対する画像情報の書き込み方式の原理を従来方式と対比させて示す説明図である。
【図７】本実施の形態の画像情報の書き込み方式を用いた場合の画像情報及び表示画像を示す模式図である。
【図８】表示データ制御手段の構成の一例を示すブロック図である。
【図９】対応する従来方式の構成例を示すブロック図である。
【図１０】変形例として２次元シフトの場合のライトバルブに対する画像情報の書き込み方式の原理を示す説明図である。
【図１１】２次元の場合の光路変調手段の原理的構成例及びその作用を説明するための側面図及び平面図である。
【図１２】本発明の第二の実施の形態の光路変調手段等の原理的構成例及びその作用を説明するための側面図である。
【図１３】その画像情報及び表示画像を示す模式図である。
【図１４】本発明の第三の実施の形態の画像表示装置全体の光学系構成を示す構成図である。
【図１５】本発明の第四の実施の形態の画像表示装置中の偏光ビームスプリッタ付近を抽出して示す構成図である。
【図１６】本発明の第五の実施の形態の画像表示装置中の偏光ビームスプリッタ付近を抽出して示す構成図である。
【図１７】本発明の第六の実施の形態の表示データ制御手段の構成例を示すブロック図である。
【図１８】そのデータ転送制御例を従来方式と対比して示すタイムチャートである。
【図１９】本発明の第七の実施の形態の表示データ制御手段の構成例を示すブロック図である。
【図２０】その変形例を示すブロック図である。
【図２１】本発明の第八の実施の形態の記憶容量に関する説明図である。
【図２２】本発明の第九の実施の形態の表示データ制御手段の構成例を示すブロック図である。
【図２３】本発明の第十の実施の形態の表示データ制御手段の構成例を示すブロック図である。
【図２４】その遅延回路の構成例を示すブロック図である。
【図２５】本発明の第十一の実施の形態中の遅延回路の構成例を示すブロック図である。
【図２６】本発明の第十二の実施の形態中の遅延回路の構成例を示すブロック図である。
【図２７】本発明の第十三の実施の形態の表示データ制御手段の構成例を示すブロック図である。
【図２８】そのラッチ動作例を示すタイミングチャートである。
【図２９】従来の画像表示装置全体の光学系構成を示す構成図である。
【図３０】その光路シフトの原理を説明するための側面図である。
【図３１】３板光学系方式の画像表示装置全体の光学系構成を示す構成図である。
【図３２】画素シフト方式を適用した場合の動作を説明するための動作説明図である。
【符号の説明】
５ｒ，５ｇ，５ｂ ライトバルブ、液晶表示素子
７ クロスダイクロイックプリズム、色合成手段
８ レンズ
１２ 照明装置
１３ 偏光回転手段
１４ 光路変調手段
１５ 偏光変調手段
１６ 光路偏向素子
１７ 偏光面回転手段
２１ 表示データ制御手段
２２ｒ，２２ｇ，２２ｂ 記憶素子、記憶領域
２４ 制御回路
３１ｒ，３１ｇ，３１ｂ ライトバルブ
３３ 偏光回転手段
４１ 偏光ビームスプリッタ
４２ 偏光分離素子
５１ 偏光ビームスプリッタ
６１ 表示データ制御手段
６２ 記憶素子
６３ｒ，６３ｇ，６３ｂ 転送用記憶素子
７１ 表示データ制御手段
７２ｒ，７２ｇ，７２ｂ 記憶素子
７４ 読み出し方法保持手段
７５ 切替手段
８１ 表示データ制御手段
８３ｒ，８３ｇ，８３ｂ 基板
８５ 記憶素子
９１ 表示データ制御手段
９２ 記憶素子
９３ タイミング制御手段
９４ 遅延回路
９６ 遅延素子
１０１〜１０３ 遅延素子
１０４〜１０９ 切替え手段
１１０ 遅延回路
１１１ 遅延素子
１１２ 接続切替え手段
１１３ 遅延回路
１２１ デジタル制御遅延素子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image display device, and more particularly to an image display device that displays an enlarged display image of a light valve.
[0002]
[Prior art]
In an image display device that enlarges and displays an image of a small image display element such as a liquid crystal display element (LCD) through a lens system, a type that is mounted or held in front of the eye called a head mounted display, There is a so-called projection type image display apparatus that projects an enlarged image on a screen and observes the projected image.
[0003]
In general, in this type of image display apparatus, the screen resolution is an important factor in determining the display quality. In a conventional enlarged projection type image display device, a method of increasing the number of display pixels of a small image display device has been adopted in order to increase the screen resolution. As a small image display element, a liquid crystal display element (TFT type LCD) in which a transistor is formed corresponding to each pixel is generally used. In such an element, miniaturization has a limit due to problems of microfabrication technology, wiring resistance, and securing of a transistor region and a wiring region, and such an element is expensive due to a decrease in yield. In addition, in the method of enlarging the element without changing the pixel density of the element, the productivity of the element is reduced, and in addition to the problem that the cost is increased, the illumination optical system and the projection optical system are enlarged, and the device This causes the problem of increasing the size and cost.
[0004]
On the other hand, according to Japanese Patent No. 2939826, a projection type image display apparatus has a birefringence effect with an optical element capable of turning a polarization direction between a display element and a screen (that is, in an output light path of the display element). A method for realizing high resolution by providing a transparent element and shifting a projected image is disclosed.
[0005]
FIG. 29 shows a configuration example of the image display device disclosed in the publication. In FIG. 24, light from the light source 202 is modulated by the display liquid crystal panel 201, and this modulated image is enlarged and projected onto the screen 204 by the projection lens 203. Between the projection lens 203 and the display liquid crystal panel 201, a polarization direction control liquid crystal panel 205 and a crystal plate 206 are provided. The main optical axis of the crystal plate 206 is arranged to be inclined with respect to the optical axis of the optical system.
[0006]
Reference numerals 207 and 208 denote frame memories, and 209 denotes a distributor.
[0007]
According to such a configuration, the optical path of light polarized in a specific direction with respect to the crystal plate 206 can be shifted by the polarization direction control liquid crystal panel 205. By operating the polarization direction control liquid crystal panel 205 at high speed and controlling the polarization state incident on the crystal plate 206, the optical path can be switched between the shifted state and the non-shifted state, and as a result, more image information is displayed. can do. This method is an effective method for high definition because high resolution can be realized using an inexpensive image display element with a small number of pixels.
[0008]
Here, the operation of the polarization direction controlling liquid crystal panel 205 and the crystal plate 206 disclosed in the above-mentioned Japanese Patent No. 2939826 will be described with reference to the principle diagram shown in FIG. The polarized light L211 incident on the polarization direction control liquid crystal panel 205 is modulated in polarization direction by the polarization direction control liquid crystal panel 205, and is incident on a crystal plate 206 having a main optical axis such as 206a. At this time, the polarized light L211p oscillating in a direction parallel to the plane formed by the main optical axis 206a of the quartz plate 206 and the optical axis of the optical system is subjected to birefringence by the quartz plate 206 and the optical path is shifted. On the other hand, the polarized light L211s oscillating in a direction perpendicular to the plane formed by the main optical axis 206a of the quartz plate 206 and the optical axis of the optical system is not subjected to birefringence by the quartz plate 206 and is emitted as it is without being deflected in the optical path. .
[0009]
FIG. 31 is a schematic diagram for explaining a typical three-plate optical system image display apparatus using a transmissive liquid crystal type light valve. The light emitted from the light source 401 illuminates liquid crystal display elements 405r, 405g, and 405b as light valves through an integrator optical system 404 configured using fly-eye lenses 402 and 403 and the like. Dichroic mirrors 406bg and 406g are provided in the optical path from the light source 401 to the liquid crystal display elements 405r, 405g, and 405b. The dichroic mirrors 406bg and 406g are provided to split white light into three color lights of red light R, green light G, and blue light B. Are configured to illuminate the liquid crystal display elements 405r, 405g, and 405b. The image light modulated by the liquid crystal display elements 405r, 405g, and 405b is synthesized by the cross dichroic prism 407 and enlarged and projected onto the screen by the projection lens 408. 409 is a field lens, 410 is a deflecting mirror, and 411 is a relay lens.
[0010]
The image light incident on the dichroic prism 407 becomes light having various incident angles by the integrator optical system 404. The incident angle characteristic of the dichroic film of the dichroic prism 407 has an angular distribution of about 1 to 2 nm / °. Since the maximum incident angle of illumination light is generally about several degrees to 10 degrees, a color shift of about 10 nm to 20 nm occurs depending on the incident angle. This incident angle characteristic is observed as display color unevenness, particularly color unevenness in the peripheral portion where the incident angle becomes large. In order to suppress such unevenness, only the green light G is incident as p-polarized light and the red light R and blue light B are incident as s-polarized light by utilizing the polarization characteristics of the dichroic film (light See Technical Contact, Vol 37, No 9). This is because the design of the dichroic film is optimized according to the polarization characteristics, and an optical element 412 that rotates the plane of polarization by 90 ° is inserted in the illumination light path of the green light G, or the liquid crystal display element 405g This is realized by inverting the on / off of the image information. At this time, only green light G is projected onto the screen as p-polarized light, and other red light R and blue light B are projected as s-polarized light.
[0011]
[Problems to be solved by the invention]
Consider a case in which a pixel shift method as disclosed in Japanese Patent No. 2939826 is applied to an image display device having such a configuration. Specifically, as shown in FIG. 31, consider a case where a polarization direction control liquid crystal panel 205 and a crystal plate 206 are provided on the outgoing light path of the dichroic prism 407.
[0012]
FIG. 32 is an operation explanatory view showing the polarization direction control liquid crystal panel 205 and the crystal plate 206 in an extracted manner. FIG. 32A is an explanatory diagram when the state of incident polarized light is not changed by the polarization direction control liquid crystal panel 205. The green image light L415 that is p-polarized light undergoes an optical path shift by the crystal plate 206, but the blue and red image light L416 that is s-polarized light undergoes no optical path shift. On the other hand, as shown in FIG. 32B, when the polarization state is changed by 90 ° by the polarization direction control liquid crystal panel 205, the green image light L415 that is p-polarized light is converted into s-polarized light. Therefore, the blue and red image lights L416, which are s-polarized light, are converted to p-polarized light and thus undergo an optical path shift. That is, the presence or absence of the optical path shift changes depending on the color, and the display is shifted by the green image light L415 with respect to the blue and red image light L416.
[0013]
In the above example, the case of the color synthesis method using the dichroic prism was taken as an example, and the case for reducing the color unevenness was explained, but in addition to this, the polarization beam splitter is used as a color synthesis means to synthesize color lights with different polarizations. There is also a known method, and even in the case of an optical system configuration using such a color synthesizing means, the same problem occurs, and the image quality is deteriorated due to pixel shift.
[0014]
Therefore, the present invention eliminates the problem of pixel shift in an image display device that performs high-definition display by combining color lights of different polarization states of a plurality of light valves and performing optical path shift. An object of the present invention is to provide an image display device with excellent uniformity.
[0015]
[Means for Solving the Problems]
The invention according to claim 1 is a plurality of light valves that perform image modulation, display data control means that controls writing of image information to these light valves, and an illumination device that illuminates each light valve with different color light, Color combining means for combining image light modulated by each light valve, and optical path modulation means for modulating the optical path of the combined image light in time division in synchronization with image modulation of the light valve. A plurality of image lights that are incident on the color synthesizing means. It has two polarization states with different polarization directions for one color light and another color light, The optical path modulation means includes Polarization modulation means for switching the polarization plane of the image light between the two polarization states, and output light in one of the two polarization states emitted from the polarization modulation means. An optical path polarizing element that bends the optical path with respect to the The display position of the display image of the light valve is changed between at least two states to superimpose the image whose display position has been changed in a time-sharing manner, and the display data control means As the display image to be written, image information at a display position corresponding to the optical path shift amount of each polarized light according to the operation state of the optical path modulation means in the image frame period is written.
[0016]
Therefore, the display unevenness due to the incident angle dependence of the color composition means is suppressed by the polarization state of at least one color being different from the polarization state of the other color light among the plurality of image lights incident on the color composition means, or In an image display device capable of performing highly efficient color composition, the image frame period includes an optical path modulation unit that modulates the optical path of the synthesized image light, and the display image to be written to each light valve during the image frame period. By writing the image information at the display position corresponding to the optical path shift amount corresponding to the polarization state according to the operating state of the optical path modulation means, it is possible to display with high resolution without color shift.
[0017]
According to a second aspect of the present invention, in the image display device according to the first aspect, the polarization of the image light incident on the color synthesizing means is linearly polarized light, and incident light having a different polarization state is polarized with other incident light. Are orthogonal.
[0018]
Therefore, by making the polarization state of the image light linearly polarized and making the difference in polarization state orthogonal, the amount of optical path shift becomes clear, and it becomes possible to appropriately deal with the correction of the writing position of image information with respect to the light valve. It is possible to display a high-resolution image without any pixel position shift accompanying the shift by the means.
[0019]
According to a third aspect of the present invention, in the image display device according to the first or second aspect, the display data control means includes the optical path modulation means for the light valve for color light having a polarization state different from that of other color light. During the image frame period in the first operation state, the image information corresponding to the display position in which the other color is in the second operation state is displayed during the image frame period in which the optical path modulation means is in the second operation state. The image information corresponding to the display position in which the other color is in the first operation state is written.
[0020]
Therefore, a specific information writing method for writing the image information at the display position corresponding to the optical path shift amount corresponding to the polarization state according to the action state of the optical path modulation means during the image frame period becomes clear, and the resolution is high without color shift. Display is possible.
[0021]
According to a fourth aspect of the present invention, in the image display device according to the first or second aspect, the light valve for the color light having a polarization state different from that of the other color light has an optical path shift amount by the optical path modulation means of s, When the pixel pitch is p and the integer is n, the pixel position is shifted from the pixel position of the other light valve by a distance corresponding to p * (n + s) in the shift direction of the optical path.
[0022]
Therefore, in addition to display with high resolution, it can be realized by a simpler information writing method.
[0023]
According to a fifth aspect of the present invention, in the image display device according to the fourth aspect, the display data control means uses the other light valve as the address position of the pixel of the light valve for the color light having a polarization state different from that of the other color light. In the sub-frame in which the optical path modulation element acts on the output polarization of the light valve, the sub-frame in which the optical path modulation element does not act on the output polarization of the light valve. In FIG. 4, image information is written at pixel positions shifted by n + 1.
[0024]
Therefore, in addition to display with high resolution, a simpler and more specific information writing method becomes clear.
[0025]
According to a sixth aspect of the present invention, in the image display device according to the fourth or fifth aspect, n = 0.
[0026]
Therefore, the optical configuration and the information writing method are most simple when n = 0, and the display area in the peripheral portion can be most effectively used.
[0027]
According to a seventh aspect of the present invention, in the image display device according to any one of the first to sixth aspects, the display data control means has a capacity for storing image information for one screen, and each light valve Read out and write to each light valve only the data required to superimpose in time when reading out the image information from the storage element, which has a storage area corresponding to the amount of image data for each color And a control circuit for controlling writing and reading of each storage area of the storage element.
[0028]
Therefore, since the data is updated without having a storage element such as a subframe buffer for each light valve, the number of parts such as a storage element and a control circuit that require a high-speed response is reduced, and cost reduction can be realized. Further, by securing a separate storage area for each light valve, each color can be easily controlled, and the control circuit can be reduced in size and the number of parts can be reduced.
[0029]
According to an eighth aspect of the present invention, in the image display device according to any one of the first to sixth aspects, the display data control means includes a storage element that stores image information for one screen, the storage element, and each of the storage elements. And a transfer storage element that is provided between the light valve and operates asynchronously with writing and reading with a capacity smaller than the number of pixels of the light valve.
[0030]
Therefore, by providing a transfer storage means between each light valve and a storage element that stores image information for one screen, the data transfer speed of the storage element such as a frame buffer is reduced, and the component cost is reduced and the operation is stable. Is realized. At this time, unlike the case of the subframe buffer, the transfer cost is reduced by using the transfer storage element having a capacity smaller than the number of pixels of the light valve and also using the period of the control signal. Stable operation is ensured with the reduction of the above.
[0031]
According to a ninth aspect of the present invention, in the image display device according to the third aspect, the display data control means includes a storage element that stores image information for one screen, the first action state, and the second action state. Reading method holding means in which at least two kinds of reading methods are set in order to read image information corresponding to a display position in the same storage element, and the reading method holding means when reading image information from the storage element Switching means for switching the readout method set in (1).
[0032]
Therefore, in realizing the image display device according to claim 3, two or more kinds of image information reading methods are defined in advance and set in the reading method holding unit, and the reading method is set as the first of the optical path modulation units. By switching according to the switching of the second action state, it is possible to read image information corresponding to the image shift from the storage element, so that the circuit size can be reduced and the component cost can be reduced without newly calculating. Is possible.
[0033]
According to a tenth aspect of the present invention, in the image display device according to the fifth aspect, the display data control means includes a storage element that stores image information for each subframe, and controls reading of the storage element. The pixel position of the image information written to the corresponding light valve is controlled by adjusting the signal timing.
[0034]
Therefore, in realizing the invention according to claim 5, the storage element can be configured with the minimum necessary capacity without waste by preparing a storage capacity corresponding to the required amount of image information. Become.
[0035]
According to an eleventh aspect of the present invention, in the image display device according to any one of the first to sixth aspects, the display data control means has a function of adjusting a transfer timing of inputted data, and each light valve Are integrally mounted on the substrate.
[0036]
Therefore, by implementing display data control means with a function to adjust the transfer timing of image information data input to each light valve itself, it is possible to write while using existing storage elements and their control circuits. Image information data can be input to the valve, and the cost of components such as peripheral circuits can be reduced.
[0037]
According to a twelfth aspect of the present invention, in the image display device according to any one of the first to sixth aspects, the display data control means includes a storage element that stores image information for one screen, and an output terminal of the storage element. And a timing control means which is provided between the light valve and the input terminal of the light valve and can adjust the data transfer timing.
[0038]
Therefore, by providing a timing control means capable of adjusting the data transfer timing between the input terminal of the light valve and the output terminal of the storage element, the existing light valve and the storage element that does not take into account the conventional shift of image information By realizing the shift of the image information while using this control configuration, the addition of a new configuration can be minimized and the cost can be reduced.
[0039]
According to a thirteenth aspect of the present invention, in the image display device according to the twelfth aspect, the timing control means includes a delay element that selectively delays a data transfer timing to the light valve by a set time.
[0040]
Therefore, the image display apparatus according to the twelfth aspect can be easily realized by using the delay element.
[0041]
According to a fourteenth aspect of the present invention, in the image display device according to the twelfth aspect, the timing control means includes a plurality of delay elements connected in series on the data line to the light valve and having different delay amounts, Switching means for switching between delay elements corresponding to each delay element or bypassing is provided, and a delay amount of data transfer timing is adjusted by a combination of switching of these switching means.
[0042]
Accordingly, in realizing the image display device according to the twelfth aspect, multistage control of the delay amount is possible, and appropriate display position control is possible.
[0043]
According to a fifteenth aspect of the present invention, in the image display device according to the twelfth aspect, the timing control unit is configured to delay the data transfer timing to the light valve by a set time, and to the light valve. Connection switching means for selectively switching the connection between the data line passing through the delay element and the data line bypassing the delay element.
[0044]
Accordingly, in realizing the image display device according to the twelfth aspect, the signal can be delayed only by the light valve that requires a delay and only by switching the connection switching means.
[0045]
According to a sixteenth aspect of the present invention, in the image display device according to any one of the thirteenth to fifteenth aspects, as the delay element, a digitally controlled delay element capable of controlling a delay amount by digital processing controlled based on a reference signal Was used.
[0046]
Therefore, in realizing the image display device according to any one of claims 13 to 15, the delay control is excellent in controllability because it is stable with respect to temperature, variation at the time of setting, etc., and does not require readjustment. Is possible.
[0047]
According to a seventeenth aspect of the present invention, in the image display device according to any one of the first to sixteenth aspects, the color synthesizing unit includes a dichroic prism.
[0048]
Accordingly, a preferred example of color composition means is provided. In particular, when a dichroic prism is used, the wavelength shift of the combined light occurs due to the incident angle characteristics of the illumination light, and the display tends to cause color unevenness, but a plurality of image light incident on the color combining means is likely to occur. By making the polarization state of at least one of the colors different from the polarization state of the other color light, it is possible to suppress display unevenness due to the incident angle dependency of the color synthesis means, and to perform highly efficient color synthesis. The image information written to each light valve during the image frame period is configured to write the image information at the display position corresponding to the optical path shift amount according to the polarization state according to the operating state of the optical path modulation means during the image frame period. Therefore, it is possible to perform display with high resolution without color misregistration.
[0049]
According to an eighteenth aspect of the present invention, in the image display device according to the seventeenth aspect, the color synthesizing means is a cross dichroic prism, and the polarized light incident on the color synthesizing means is only green light as p-polarized light and other red light. The blue light was s-polarized light.
[0050]
Therefore, a more specific configuration example of the image display device according to the fourteenth aspect is clarified.
[0051]
According to a nineteenth aspect of the present invention, in the image display device according to the seventeenth or eighteenth aspect, at least one of the plurality of image lights incident on the color synthesizing means is provided by providing a polarization rotation means in the illumination optical path of the illumination apparatus. The polarization state of one color is different from the polarization state of the other color light.
[0052]
Therefore, a specific example is provided in which the polarization state of at least one color among the plurality of image lights incident on the color composition unit is different from the polarization state of the other color light.
[0053]
According to a twentieth aspect of the present invention, in the image display device according to the seventeenth or eighteenth aspect, among the plurality of image lights incident on the color synthesizing means by inverting on / off of image information written to the light valve. The polarization state of at least one color is different from the polarization state of the other color light.
[0054]
Therefore, a simple and efficient concrete example is provided in which the polarization state of at least one color out of the plurality of image lights incident on the color composition means is different from the polarization state of the other color light.
[0055]
According to a twenty-first aspect of the present invention, in the image display device according to any one of the first to sixteenth aspects, the color synthesizing unit includes a polarization beam splitter.
[0056]
Accordingly, a preferred example of color composition means is provided. In particular, in the synthesis by the polarization beam splitter, two types of polarized light having different polarization states of the combined light are mixed, but the display position corresponding to the optical path shift amount according to the polarization state depending on the operation state of the optical path modulation means in the image frame period. With the configuration in which the image information is written, even when the optical path modulation means is provided, it is possible to perform display with high resolution without pixel shift due to color.
[0057]
According to a twenty-second aspect of the present invention, in the image display device according to the twenty-first aspect, the color synthesizing unit emits the polarization rotating unit that converts the polarization direction of the specific color light into the orthogonal polarization direction and the polarization rotating unit. A polarization separation element that separates the optical path of the illumination light by polarization; and a polarization beam splitter that combines the outgoing light beams that are separated by the polarization separation element and modulated by the light valves.
[0058]
Therefore, in realizing the invention according to claim 21, a compact and highly efficient optical system configuration is provided.
[0061]
Claim 23 The described invention Claim 1 In the image display device described above, the polarization modulation unit is a liquid crystal element, and the optical path deflecting element is a uniaxial optical anisotropic body having a main optical axis inclined with respect to the optical axis.
[0062]
Therefore, Claim 1 In realizing the described invention, a preferred example of an optical path deflecting element is provided.
[0063]
Claim 24 The described invention Claim 23 In the image display device described above, the liquid crystal element as the polarization modulation unit is a ferroelectric liquid crystal element.
[0064]
Therefore, Claim 23 In the described invention, by using a liquid crystal element composed of a ferroelectric liquid crystal having a high response speed, it is possible to realize an operation of switching incident polarized light to two polarization states having orthogonal polarization planes with high responsiveness.
[0065]
Claim 25 The described invention Claim 23 or 24 In the image display device described above, the uniaxial optical anisotropic body as the optical path deflecting element is made of a lithium niobate crystal.
[0066]
Therefore, Claim 23 or 24 In the image display device described above, a preferable configuration example can be provided by using a lithium niobate crystal having excellent stability, cost, and transparency as the uniaxial optical anisotropic body.
[0067]
Claim 26 The described invention Claims 1 to 25 The image display device according to any one of the above, further comprising a plurality of the optical path modulation means having different directions in which the optical path is bent or shifted, and a polarization plane rotating means on the optical path between these optical path modulation means.
[0068]
Therefore, since optical path modulation can be performed two-dimensionally, higher resolution can be obtained.
[0069]
Claim 27 The described invention Claims 1 to 26 In the image display device according to any one of the above, the light valve is a liquid crystal display element using a ferroelectric liquid crystal.
[0070]
Therefore, a preferred configuration example is provided by using a liquid crystal display element of ferroelectric liquid crystal that operates digitally as a light valve.
[0071]
Claim 28 The described invention Claims 1 to 26 In the image display device according to any one of the above, the light valve is a liquid crystal display element made of antiferroelectric liquid crystal.
[0072]
Therefore, a suitable configuration example suitable for halftone expression is provided by using a liquid crystal display element made of antiferroelectric liquid crystal having excellent response speed as a light valve.
[0073]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS. The image display apparatus of the present embodiment shows an application example to a projection type image display apparatus that projects an enlarged image on a screen and observes the projection image.
[0074]
FIG. 1 is a configuration diagram showing an optical system configuration of such an entire image display apparatus. First, light emitted from the light source 1 illuminates transmissive light valves 5r, 5g, and 5b through an integrator optical system 4 configured using fly-eye lenses 2, 3 and the like. Dichroic mirrors 6bg, 6g are provided in the optical path from the light source 1 to the light valves 5r, 5g, 5b, and the white light is split into three color lights of red light R, green light G, and blue light B, and each color light is separated. Each light valve 5r, 5g, 5b is configured to illuminate. The image light that has been image-modulated by the light valves 5r, 5g, and 5b is combined by a cross dichroic prism 7 as color combining means, and enlarged and projected onto a screen by a projection lens 8 as a lens. Reference numeral 9 is a field lens, 10 is a deflecting mirror, and 11 is a relay lens. The light source 1, the integrator optical system 4, the dichroic mirrors 6bg and 6g, the deflecting mirror 10, the relay lens 11 and the like constitute an illumination device 12 for the light valves 5r, 5g and 5b.
[0075]
The lights modulated by the light valves 5r, 5g, and 5b are combined by the cross dichroic prism 7, and the combined image light is enlarged and projected onto the screen (not shown) by the projection lens 8.
[0076]
Here, a polarization conversion element is provided in the illumination light path in the illumination device 12 as needed, and the polarization of the illumination light is controlled to be a specific linear polarization. In the present embodiment, there is provided a polarization rotation element 13 as a polarization rotation means such as a half-wave plate for rotating the polarization direction of the green light G incident on the light valve 5g by 90 °. Accordingly, the polarization of the image light incident on the cross dichroic prism 7 is set so that only the green light G is p-polarized light and the other red light R and blue light B are s-polarized light.
[0077]
Each light valve 5r, 5g, 5b displays an image depending on whether or not the polarization of incident light is rotated by 90 °. As such light valves 5r, 5g, and 5b, known display elements such as a 90 ° twisted liquid crystal display element, a vertically aligned liquid crystal display element, and a liquid crystal display element using a ferroelectric liquid crystal can be used.
[0078]
In addition, although the example using the polarization | polarized-light rotation element 13 like a 1/2 wavelength plate was shown in FIG. 1, by reversing the display of the said light valve 5g, ie, turning on / off of image information, The polarization of the light emitted from the light valve 5g can be changed. This method is more preferable because only the image data is inverted and no other optical element such as the polarization rotation element 13 is required.
[0079]
Non-image light among the light modulated by the light valves 5r, 5g, and 5b is removed by a polarizer (not shown) provided on the emission side of the light valves 5r, 5g, and 5b, and only image light is present. The light enters the cross dichroic prism 7. At this time, the green light G is incident on the cross dichroic prism 7 as linearly polarized light (p-polarized light) having a vibration direction different from the red light R and the blue light B in the s-polarized state by 90 °. With such a configuration, as described above, the use of the integrator optical system 4 provides optical characteristics that are less likely to cause color unevenness even when the incident angle of illumination light with respect to each light valve 5r, 5g, 5b is large. It is done.
[0080]
Further, on the optical path between the cross dichroic prism 7 and the projection lens 8, an optical path modulation means 14 for performing pixel shift is provided. An example of the basic configuration of the optical path modulation means 14 and its operation when color synthesis is performed by the cross dichroic prism 7 will be described with reference to FIG. The optical path modulation means 14 in this case is a polarization modulation means 15 for controlling the polarization plane of the incident image light, and the optical path is bent (or shifted) with respect to a specific polarization state of the specific outgoing light from the polarization modulation means 15. ) To be combined with the optical path deflecting element 16.
[0081]
Each color light separated by the illumination device 12 is polarization-modulated by the light valves 5r, 5g and 5b and enters the cross dichroic prism 7 which is a color synthesizing means. At this time, at least one color, in the present embodiment, green light is incident on the cross dichroic prism 7 with a plane of polarization different from that of the other color light by 90 °.
[0082]
2A shows a state in which the optical path modulation means 14 bends the p-polarized light and does not bend the s-polarized light. FIG. 2B shows a state in which the optical path modulation means 14 bends the p-polarized light and s-polarized light. Represents a state without bending.
[0083]
In this embodiment, such an optical path modulation means 14 is composed of a polarization modulation means 15 capable of modulating the polarization direction of incident light and an optical path deflecting element 16, and FIG. Shows the optical path when polarization does not act and polarization is maintained. The case where the uniaxial crystal which has the main optical axis inclined with respect to the optical axis is used for the optical path deflection element 16 is shown. The optical axis of the crystal is in a plane including at least one polarization plane in at least one polarization direction of the outgoing light of the polarization modulator 15. In FIG. 2, 16a represents the main optical axis.
[0084]
In such a configuration, the light polarized in the plane including the main optical axis 16a and the optical axis (p-polarized light) is subjected to birefringence by the optical path deflecting element 16 as shown as polarized light L18 in FIG. Is bent. On the other hand, the polarized lights L17 and L19 (s-polarized light) orthogonal to the plane including the main optical axis 16a and the optical axis travel straight without being subjected to birefringence by the optical path deflecting element 16. That is, the optical path of the p-polarized light from the light valve 5g is bent by the optical path modulation means 14, and the s-polarized light from the light valves 5r and 5b travels straight through the optical path modulation means 14. The polarization modulation means 15 is provided to control the polarization direction of the outgoing polarized light, and in the figure, switches between polarized light that vibrates in the vertical direction (p-polarized light) and polarized light that vibrates in the direction perpendicular to the paper surface (s-polarized light). To do.
[0085]
FIG. 2B is a diagram when the polarization modulation means 15 is operated to rotate the polarization direction of the light emitted from the cross dichroic prism 7 by 90 °. In this case, since the s-polarized light from the light valves 5r and 5b is converted into p-polarized light by the polarization modulating means 15, the optical path is bent by the optical path deflecting element 16, and the p-polarized light from the light valve 5g is converted by the polarization modulating means 15. Since it is converted into s-polarized light, the light path deflecting element 16 goes straight.
[0086]
As described above, the polarization modulation means 15 has a function of switching incident polarized light between two polarization states whose polarization planes are orthogonal to each other at high speed, and can realize an area for a display device at a low cost. Liquid crystal devices such as ferroelectric liquid crystal, π cell, and twisted nematic liquid crystal are suitable. Of these, twisted nematic liquid crystal with a liquid crystal layer thickness of 3 μm or less, nematic liquid crystal system driven by two frequencies, π-cell, and ferroelectric liquid crystal are particularly suitable because of their fast response speed, and the most responsive. An excellent ferroelectric liquid crystal is optimal. These act as polarization modulation means by controlling the optical rotatory action or the action as a half-wave plate by an external electric field.
[0087]
The optical path deflecting element 16 bends (or shifts) the optical path with respect to light having a specific polarization direction. Specifically, the optical path deflecting element 16 is quartz, mica, lithium niobate, KH. ₂ PO ₄ LiTaO ₃ An optical crystal obtained by cutting an optical crystal such as the above obliquely with respect to the main optical axis is suitable. Above all, from the viewpoint of stability, cost, and transparency, crystal, lithium niobate, LiTaO ₃ Is particularly preferably used.
[0088]
FIG. 3 illustrates the operation of the optical path modulation means 14 by taking L17 as red light in FIGS. 2 (a) and 2 (b) as an example. In the figure, the case where the optical path modulator 14 shifts the image light by p / 2 with respect to the pitch p in the shift direction of the pixels of the light valve 5r is described. FIG. 3 (a) schematically shows an image on the light valve 5r in an image frame in which the polarization modulator 15 does not act. FIG. 3B shows the display image and is not shifted. FIG. 3 (c) schematically shows an image on the light valve 5r in an image frame in which the polarization modulation means 15 acts. FIG. 3D shows the display image, which is shifted.
[0089]
By operating the polarization modulation means 15 in synchronization with the switching of the images in FIGS. 3A and 3C, the display images in FIGS. 3B and 3D are displayed in a time-sharing manner. . At this time, when the frame frequency of the image frame is 30 Hz or higher, preferably 40 Hz or higher, particularly preferably 60 Hz or higher, the observer's eyes are the combined images of FIG. 3B and FIG. ) Is observed without flicker, and a resolution twice that of the original image is obtained.
[0090]
By the way, in the present embodiment, as described above, the polarization state of at least one color among the plurality of image lights incident on the cross dichroic prism 7 is different from the polarization state of the other colors. In FIG. 2, the image light L18 from the light valve 5g for green light is p-polarized, whereas the image lights L17 and L19 of other colors are s-polarized. At this time, as shown in FIG. 2, the image light L18 (p-polarized light) and the image light L17, L19 (s-polarized light) are reversely subjected to the optical path shift effect received by the optical path modulation means 14.
[0091]
FIG. 4 illustrates this phenomenon with the same notation as in FIG. That is, FIGS. 4A to 4E have the same meaning as FIGS. 3A to 3E. FIG. 4 illustrates a case where red and green are combined and a yellow “A” character is combined and displayed. The green image light L18 shown on the right side in FIG. 4 is different from the red image light L17 shown on the left side in FIG. 4 because the action of the optical path modulation means 14 is different from that shown in FIG. The image state is greatly deformed. FIG. 5 is a composite image at this time, and it can be seen that a pixel shift has occurred.
[0092]
In order to avoid the phenomenon that the image quality is deteriorated due to such pixel shift, in this embodiment, the light path modulation means 14 is in the first action state in the light valve 5g for the color light having a polarization state different from that of the other color light. The image information corresponding to the display position in which the other color is in the second operation state during one image frame period, and the other color is the first in the image frame period in which the optical path modulation means 14 is in the second operation state. The display data control means (described later) controls the writing of the image information to the light valve 5g so as to display the image information corresponding to the display position in the operating state.
[0093]
The principle of such image information writing control will be described with reference to FIG. The operating state (ON / OFF) of the optical path modulation means 14 corresponds to the display frame. An image frame period required to display the entire screen is composed of subframes divided by the number of operating states of the optical path modulation means 14, and the display data control means is determined by the optical path modulation means 14 during the subframe period. The image corresponding to the display position to be written is written. At this time, when all the outgoing polarizations are the same as in the prior art, the adjacent pixels 1 and 2 are sequentially displayed with information of each color by switching the optical path modulation means 14. For example, as shown in the upper part of FIG. 6, when the pixel 1 is blue and the pixel 2 is yellow for the adjacent pixels 1 and 2, the light valve 5b is blue in the first subframe and the second subframe. Display can be performed by turning on red and green of the light valves 5r and 5g. On the other hand, in the configuration of the present embodiment, the output polarization differs depending on the color light, and the action of the optical path modulation means 14 is reversed by the polarization, so that the color information of the pixels 1 and 2 is displayed during the same subframe period. Will be. Therefore, in the present embodiment, green light (in this case) that is different from other polarized light that should originally be lit in the second subframe is lit in the first subframe, so that the original image position is green. Is displayed. If it is desired to display green on the pixel 1, the second frame in which image information corresponding to the other color corresponding to the pixel 2 is displayed in green. As described above, in the present embodiment, for color light having a different polarization from the others, the optical path modulation means 14 writes the image information of the subframe in a different operation state, thereby displaying a desired color misalignment. It is what you want to do.
[0094]
FIG. 7 shows an image writing method of the image display apparatus according to the present embodiment based on such an image information writing principle, as compared with the case of FIG. As in the previous drawings, the optical path modulation means 14 performs p / 2 optical path modulation. 7A to 7E have the same meanings (states) as in FIGS. 3A to 3E and 4A to 4E, respectively. Further, green light having different polarization directions shown on the right side is distinguished as shown in (a ′) to (e ′). The display image of the light valve 5g for green light having a different polarization direction is shown in FIG. 7 (b ') in a state where, for example, the optical path modulation means 14 does not act on red light and acts on green light. As shown in FIG. 7, an image of red light in a state where the optical path modulation means 14 is in the other action state, that is, the optical path modulation means 14 acts on red light and does not act on green light (FIG. 7D). ) Is displayed.
[0095]
With such a configuration, the composite image can be a desired image as shown in FIGS. Note that FIG. 7 shows an example in which two colors are combined at the same position and yellow is displayed, so FIG. 7 (b ′) and FIG. 7 (e ′) are the same images, but the actual written image is Generally not the same. As described above, in the present embodiment, image information in consideration of the optical path shift amount due to the action state of the optical path modulation means 14 due to polarization is written into the light valve 5 in the same image frame period. By operating in this way, even in an image display device in which the output polarized light is different depending on the color light, a high-quality image without a color shift of high resolution is provided by the action state of the optical path modulation means 14.
[0096]
Here, an example of the configuration of the display data control means 21 that performs such image information writing control will be described with reference to FIG. The display data control means 21 in the illustrated example has a capacity for storing image information for one screen each, and the image data amount of each RGB color for each light valve 5r, 5g, 5b (using dielectric liquid crystal). Frame buffers 22r, 22g, and 22b as storage elements in which corresponding storage areas are secured, and only data that is at least necessary for temporal superposition when reading image information from these frame buffers 22r, 22g, and 22b The storage element control circuit 24 is configured as a control circuit for controlling writing and reading to the frame buffers 22r, 22g, and 22b so as to read and write to the light valves 5r, 5g, and 5b.
[0097]
The input display signals (image information) are stored in the frame buffers 22r, 22g, and 22b, respectively. In the present embodiment, image data for superimposing a plurality of screens in a time-sharing manner is read directly from the frame buffers 22r, 22g, and 22b under the control of the storage element control circuit 24. In the frame buffers 22r, 22g, and 22b, individual elements are used for each RGB corresponding to the three primary colors RGB. Accordingly, each color can be individually controlled with respect to the case where the three primary colors are integrated, and can be realized by controlling only the necessary colors. However, the frame buffers 22r, 22g, and 22b do not necessarily have to be individual elements as long as the light valves 5r, 5g, and 5b to be used can be individually accessed. That is, a part surrounded by a dotted line in FIG. 8 may be configured as one memory element 23, and a product in which the inside is divided into three banks may be used. In this case, it is possible to further reduce the number of parts, the mounting process, and the like.
[0098]
According to this, since the data is updated without having a separate subframe buffer for the light valves 5r, 5g, and 5b, the number of components such as a storage element and a control circuit that require a high-speed response is reduced, and cost reduction is realized. it can. Further, by securing separate storage areas (frame buffers 22r, 22g, and 22b) for the RGB three primary colors, each color can be easily controlled, and the control circuit 24 is downsized and the number of parts is reduced. Can be realized.
[0099]
Specifically, when a prototype was made for the display capacity SXGA (1280 × 960), the system of the present embodiment realized a 5% reduction in the number of parts compared to the case where each color was integrated. Incidentally, as a comparative example, as shown in FIG. 9, a circuit having a dedicated storage element (subframe buffer 25r, 25g, 25b) for each light valve 5r, 5g, 5b was created. In the comparative example, after writing to the frame buffer 26, the image data of the sub-frame buffers 25r, 25g, 25b corresponding to the individual light valves 5r, 5g, 5b is read from the frame buffer 26, and the respective light valves 5r, 5g, The subframe buffers 25r, 25g, and 25b corresponding to 5b are written, and the light valves 5r, 5g, and 5b display according to the contents of the subframe buffers 25r, 25g, and 25b.
[0100]
According to the present embodiment, the storage capacity of the storage elements (frame buffers 22r, 22g, 22b) is equal to the display capacity (number of pixels) of the light valves 5r, 5g, 5b. On the other hand, in the comparative example, in addition to the frame buffer 26, the sub-frame buffers 25r, 25g, 25b require a storage capacity equivalent to the display capacity of the individual light valves 5r, 5g, 5b. It is. Since this storage capacity requires high-speed operation, it is generally expensive, and the cost of parts in the comparative example as a whole is higher than in the case of this embodiment (about 2.2 times). Regarding the circuit scale, in the present embodiment, the control circuit 24 directly performs input / output control of the frame buffers 22r, 22g, and 22b, whereas in the comparative example, in addition to the input / output control of the frame buffer 26, the light valve The control circuits 27r, 27g, and 27b for the sub-frame buffers 25r, 25g, and 25b for 5r, 5g, and 5b are necessary (about 1.8 times).
[0101]
The display data control means 21 of the present embodiment can realize a reduction in cost by reducing the circuit scale, reducing the number of storage elements, and reducing the number of components.
[0102]
In the above description, the pixel shift is performed only in one direction in the horizontal direction (or the vertical direction) and the resolution is increased by two times. However, the resolution is not limited to two times. The present invention can also be applied to the case where the resolution is increased four times by performing a two-dimensional pixel shift.
[0103]
FIG. 10 is a diagram for explaining the principle of write control when two-dimensional (vertical / horizontal) pixel shift is performed by providing optical path modulation means in the x and y directions. In this case as well, as in the one-dimensional case whose principle is explained in FIG. 6, the light path modulation means is different for the light valve 5g of colored light having different polarization (in this case, green light). By writing the image of the subframe in the active state, it is possible to perform display without a desired color shift.
[0104]
11 shows an example of the configuration of an optical system for performing two-dimensional pixel shift as shown in FIG. 10, FIG. 11 (a) is a side view, and FIG. 11 (b) is a plan view thereof. In this case, an optical path modulation unit 14x that performs optical path modulation in the x direction and an optical path modulation unit 14y that performs modulation in the y direction are provided on the same optical path. Each of the optical path modulation means 14x and 14y is composed of a pair of polarization modulation means 15x and 15y and optical path deflection elements 16x and 16y. At this time, the main optical axis 16ya of the optical path deflection element 16y is inclined in a direction orthogonal to the inclination direction of the main optical axis 16xa of the optical path deflection element 16x. A polarization plane rotating unit 17 is provided between the optical path modulating units 14x and 14y to rotate the polarization direction of the polarized light emitted from the optical path modulating unit 14x by 90 °. As the polarization plane rotating means 17, a half phase plate, twisted liquid crystal, or the like can be used.
[0105]
11 (a) and 11 (b) show an operating state in a state where the polarization modulation means 15x acts and the change modulation means 15y does not act.
[0106]
With such a configuration, it is possible to further optically modulate the light path modulated in the x direction by the optical path modulator 14x in the y direction by the optical path modulator 14y. Therefore, the display pixels of the light valves 5r, 5g, and 5b can be displayed in a two-dimensional manner, substantially four times in length and width, and higher resolution can be achieved.
[0107]
In any case, in the present embodiment and subsequent embodiments, the display image field is divided into a plurality of subfields, and the optical path of the image light is modulated by the optical path modulation means 14 (14x, 14y) for each subfield. (Bending or shifting) and displaying the number of pixels multiplied with respect to the original image in a time-sharing manner. At this time, the display images of the light valves 5r, 5g, and 5b need to be switched according to the subfield. For this reason, the light valves 5r, 5g, and 5b are required to have a response speed that is at least twice that of the case where the optical path modulation means 14 is not used, and the light valves 5r, 5g, and 5b have the illumination light as described above. Those that modulate polarized light are preferably used. From the above, as the light valve, particularly a liquid crystal light valve having a high-speed response, for example, a liquid crystal display mode using a high-speed response liquid crystal display mode such as a ferroelectric liquid crystal, an antiferroelectric liquid crystal, or a π cell is suitable. is there. In particular, a liquid crystal display element using a ferroelectric liquid crystal element operates digitally and has excellent digital characteristics, and a liquid crystal display element using an anti-ferroelectric liquid crystal element has a high response speed. This is suitable for halftone expression.
[0108]
In this embodiment and the following embodiments, the optical path shift amount s by the optical path modulator 14 is set to p, the pixel pitch of the light valves 5r, 5g, 5b is p, in order to obtain a uniform image with high resolution. When m is an integer, it is preferably approximately (m ± 1/2) p. If the integer m is too large, the peripheral pixels cannot be used effectively, so m is preferably in the range of 0 to 10. Moreover, since controlling a large optical path shift amount has a technical problem, m is preferably in the range of 0 to 4. As a preferable example of the present embodiment, substantially (m ± 1/2) p means (m + 1/4) p to (m + 3/4) p or (m−3 / 4) p to (m−1 / 4) The range of p can be mentioned. If the shift amount is outside this range, it is difficult to obtain a sufficient resolution.
[0109]
A second embodiment of the present invention will be described with reference to FIGS. The same parts as those shown in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted (the same applies to the following embodiments).
[0110]
In this embodiment, the pixel position of the light valve (in this embodiment, the light valve 5g for green light) with respect to color light having a polarization state different from that of other color light is changed to the other light valve (in this embodiment, red light). The optical path shift by a distance s (s = p / 2 in the present embodiment) substantially equivalent to the optical path shift amount of the optical path modulation means 14 with respect to the pixel position of the blue light bulbs 5r, 5b). The display data control means controls the writing position of the image information to the light valve in accordance with the action state of the optical path modulation means 14 so that the projected images in different polarization states can be arranged. In this configuration, the images are displayed so as to overlap during the same image frame period. Here, “substantial” means a relative positional relationship in consideration of bending of the optical axis.
[0111]
FIG. 12 shows an extracted configuration in the vicinity of the cross dichroic prism 7 and the optical path modulation means 14 in order to explain such a configuration action. FIG. 12A shows a state in which the polarization modulation means 15 is not acting ( FIG. 12B is a side view of the state in which the polarization modulator 15 is acting (second action state).
[0112]
In the state shown in FIG. 12A, the red and blue image lights L17 and L19, which are s-polarized light, are emitted from the optical path modulation means 14 without being subjected to the optical path shift by the optical path deflecting element 16, as indicated by the solid line. On the other hand, the green image light L18 that is p-polarized light undergoes an optical path shift of p by the optical path deflecting element 16. At this time, the pixel 5gp1 of the light valve 5g in which the green image information is written is a distance s corresponding to the optical path shift with respect to the pixels 5rp1 and 5bp1 of the light valves 5r and 5b in which the image information of other colors is written. Since the writing is shifted by the minute amount, the optical path shift amount with respect to the red and blue image lights L17 and L19 is 2 s, that is, a shift amount corresponding to one pitch of the light valve.
[0113]
On the other hand, when the polarization modulator 15 is operating, as shown in FIG. 12B, the red and blue image lights L17 and L19, which are s-polarized light, are converted into p-polarized light by the polarization converter 15, so that the solid line. As shown in FIG. 2, the optical path deflecting element 16 receives an optical path shift of p / 2. On the other hand, the green image light L18, which is p-polarized light, is converted into s-polarized light by the polarization conversion means 15, so that it is emitted from the optical path modulation means 14 without being subjected to an optical path shift by the optical path deflecting element 16. At this time, the pixel 5gp1 of the light valve 5g in which the green image information is written is a distance s corresponding to the optical path shift with respect to the pixels 5rp1 and 5bp1 of the light valves 5r and 5b in which the image information of other colors is written. As a result, the optical path of the light emitted from the optical path modulation means 14 can be the same as the other colors.
[0114]
That is, in a state where the optical path modulation means 14 acts only on the green image light L18 (FIG. 12A), an image for the same subframe as the other colors is displayed, and the optical path modulation means 14 applies to the green image light L18. In the state where it does not act on other colors but acts on other colors (FIG. 12B), it is only necessary to write image information at adjacent address positions into the light valve in the same image frame. FIG. 13 shows the relationship between the image information written to the light valve 5 and the display image in the case of the present embodiment when described in the same manner as FIG.
[0115]
In the case of the configuration of the present embodiment, the images that are simultaneously written to the light valves 5r and 5b and the light valve 5g are even columns (rows) or odd columns (rows) of the display image of the same subframe data. There is an advantage that the light valve write data can be easily generated from the data and the control circuit (display data control means) can be simplified.
[0116]
In the present embodiment, the pixel position of the light valve 5g is shifted by p / 2. However, the address position of the write image information is shifted by p * (n + 1/2) and corresponding to n. The same effect can be obtained even when writing is performed with a relative shift. Here, n is an integer. That is, the image information shifted by n lines and the image information shifted by n + 1 lines with respect to the other light valves may be switched in subframes in accordance with the operation state of the optical path modulation means. However, since the peripheral image cannot be used effectively when the absolute value of n increases, the absolute value of n is preferably 10 or less, more preferably 5 or less, and even more preferably 2 or less. Most preferably n = 0.
[0117]
In the configuration of the present embodiment, when two-dimensional optical path modulation is performed, the same configuration as that shown in FIG. 11 is adopted, and the pixel position of the light valve 5g having a polarization direction different from that of other color light. Are shifted by p * (n + 1/2) in the x and y directions with respect to the pixel positions of the other light valves 5b and 5r, and are determined by the combination of the operations of the optical path modulation means 14x and 14y for x and y. Control may be performed so that image information shifted by n lines in the x direction and y direction or image information shifted by n + 1 lines is displayed in the image subframe.
[0118]
A third embodiment of the present invention will be described with reference to FIG. The present embodiment shows an application example to an image display device configured by using reflective light valves 31r, 31g, and 31b instead of the transmissive light valves 5r, 5g, and 5b. Basically, it is the same as that shown in FIG. 1, but in this embodiment, polarizing beam splitters 32r, 32g, and 32b are interposed between the light valves 31r, 31g, and 31b and the cross dichroic prism 7. Has been.
[0119]
In the present embodiment, the phase difference plate 33 is used so that the polarization state of only the green light is different from the polarization state of the other color light. However, by devising the configuration and arrangement of the polarization beam splitter. You may comprise without the phase difference plate 33. FIG. Further, the output polarization of the light valve 31g can be changed by inverting the display of the image information on the light valve 31g (inverting on / off) without using an optical element such as the phase difference plate 33. This method is more preferable because it only inverts image data and does not use any other optical element.
[0120]
A fourth embodiment of the present invention will be described with reference to FIG. The present embodiment shows an application example in the case where the color combining means is configured using a combination of a polarization beam splitter 41 and a dichroic prism 42 as a polarization separation element instead of the cross dichroic prism 7.
[0121]
A wavelength-selective phase difference plate 43 as a polarization rotating means is provided at a position where the illumination light from the illumination device is incident on the polarization beam splitter 41. This wavelength-selective phase difference plate 43 is an element having a function capable of converting only the color light of a specific wavelength into a change direction in which the polarization direction is orthogonal, and is, for example, a product name “Color Select” from Color Link. A commercially available optical element is used. Here, green light is emitted to the polarization beam splitter 41 as p-polarized light, blue light and red light as s-polarized light.
[0122]
The dichroic prism 42 is adjacent to the reflection side of the polarization beam splitter 41, and functions to split the s-polarized light reflected by the polarization beam splitter 41 into a red light component and a blue light component. Reflective light valves 31r and 31b are arranged in the traveling direction of red light and blue light separated by the dichroic prism. The image light (p-polarized light) modulated by the light valves 31r and 31b passes through the polarization beam splitter 41, and is projected toward the screen via the optical path modulation means 14 and the projection lens 8 as described above.
[0123]
On the other hand, a reflective light valve 31g is disposed on the transmission side of the polarization beam splitter 41 via a glass block 44 for matching the optical path length. The image light (s-polarized light) transmitted through the polarization beam splitter 41 and modulated by the light valve 31g is reflected by the polarization beam splitter 41 and projected toward the screen via the optical path modulation means 14 and the projection lens 8 as described above. The
[0124]
In the present embodiment, the light valve 31g for green light is used for p-polarized illumination, but other color light may be p-polarized light.
[0125]
According to the configuration of the present embodiment, there is an advantage that the optical system can be configured relatively small as compared with the case where the cross dichroic prism 7 as described above is used.
[0126]
A fifth embodiment of the present invention will be described with reference to FIG. The present embodiment shows an application example in the case where the color synthesizing means is configured by only the polarization beam splitter 51.
[0127]
A phase difference plate 52 is provided at a position where the illumination light from the illumination device is incident on the polarization beam splitter 51. The retardation plate 52 is an optical element that has wavelength selectivity such as that commercially available from Color Link under the trade name “Color Switch” and that can electrically control the action thereof. The retardation plate 52 controls, for example, whether red light is always emitted as p-polarized light and whether green light and blue light are emitted as s-polarized light. A reflection light valve 31r for red is disposed on the transmission side of the polarization beam splitter 51 with respect to incident light, and a light valve 31bg for both blue and green is disposed on the reflection side. By the action of the phase difference plate 52, the s-polarized light emitted between the blue light and the green light is sequentially switched, and the image information for the blue / green combined light valve 31bg is written in the image information corresponding to each color in synchronization with it. By changing, it is possible to synthesize three colors in time.
[0128]
In the configuration of the present embodiment, red image light is emitted as s-polarized light, and green and blue image light is emitted as p-polarized light.
[0129]
According to this embodiment, the optical system can be further reduced in size.
[0130]
In the case of the third, fourth and fifth embodiments, the two-dimensional optical path modulation means 14x and 14y for the x direction and y direction as shown in FIG. Optical path shift is possible, and higher resolution can be obtained.
[0131]
A sixth embodiment of the present invention will be described with reference to FIGS. The present embodiment shows an example of the display data control means 61 that controls the writing of image information to each light valve 5r, 5g, 5b (may be 31r, 31g, 31b).
[0132]
As shown in FIG. 17, the display data control means 61 of the present embodiment includes a frame buffer 62 as a storage element for storing image information for one screen, the frame buffer 62 and the light valves 5r, 5g, 5b, FIFO (First In First Out) as a transfer storage element that operates asynchronously with a capacity smaller than the number of pixels of each light valve 5r, 5g, 5b, for example, a capacity of 1/10. ) Memory 63r, 63g, 63b. As a result, the display signal (image information) from the frame buffer 62 is input to the light valves 5r, 5g, and 5b via the FIFO memories 63r, 63g, and 63b under the control of the storage element control circuit 64.
[0133]
In such a configuration, for example, a data transfer method using a configuration without the FIFO memories 63r, 63g, and 63b will be described with reference to a time chart shown in FIG. In this case, since the position of the display data is specified and transferred by the synchronization signal in a certain period (for example, every scanning line), the time that can be used for the transfer of the display data is shown in FIG. In this way, the control signal is limited between the synchronization signals.
[0134]
On the other hand, the data transfer method in the present embodiment will be described with reference to the time chart shown in FIG. 18A. The control signal serving as the synchronization signal is used to indicate the start of display data input. Once the data transfer is started, a plurality of scanning line information is transferred as continuous data using the FIFO memories 63r, 63g, and 63b. Therefore, the transfer time by the control signal is compared with the method of FIG. The limit is shorter. As a whole, since the time available for data transfer becomes longer when compared with the same frame time, the data transfer clock can be lowered.
[0135]
Thus, since the transfer clock for the frame buffer 62 can be lowered, the operating frequency of the storage element (frame buffer 62) and the light valves 5r, 5g, 5b to be used can be lowered, and the lower operating frequency can be reduced. The product can be used. Even when products having the same operating frequency are used, the method according to the present embodiment allows a more stable operation because the margin is wider than the actual driving frequency. Further, unlike the subframe buffers 25r, 25g, and 25b as shown in FIG. 9, storage elements (FIFO memories 63r, 63g, and 63b) having a capacity smaller than the number of pixels of the light valves 5r, 5g, and 5b are provided. Since the control signal period is used to reduce the speed, the component cost can be reduced and stable operation can be realized.
[0136]
A seventh embodiment of the present invention will be described with reference to FIG. This embodiment also shows an example of the display data control means 71 that controls the writing of image information to each light valve 5r, 5g, 5b (may be 31r, 31g, 31b).
[0137]
As shown in FIG. 19, the display data control means 71 of the present embodiment includes storage elements 72r, 72g, 72b such as a frame buffer for storing image information for one screen, and an optical path modulation means 14 having a first action. In order to read out the image information corresponding to the display position in the state and the second operation state from the same storage element 72r, 72g, 72b, at least two kinds of control patterns are previously stored by the storage element control signal generation circuit 73 as the reading method. An EEPROM 74 (which may be an EPROM, a ROM, etc.) as a set readout method holding means and an optical path modulation means switching signal when the storage element control signal generation circuit 73 reads out image information from the storage elements 72r, 72g, 72b. As a switching means for switching the control signal by the reading method set in the EEPROM 74 according to the And a switching circuit 75 of the multiplexer or the like.
[0138]
That is, in this embodiment, two types of output control patterns are prepared in advance in the control circuit 73 that outputs the address of the frame buffer (storage elements 72r, 72g, 72b). This output control pattern is created by a combinational circuit, and each read pattern is output by switching each control signal. As a control signal in this case, an optical path modulation means switching signal for switching the first action state and the second action state of the optical path modulation means 14 is used. The frame buffer (storage elements 72r, 72g, 72b) is controlled by the switching circuit 75 and the output to each light valve 5r, 5g, 5b is controlled.
[0139]
As described above, according to the present embodiment, two or more types of image information readout methods are defined in advance and set in the readout method holding unit, and the readout method is set in the first and second optical path modulation units. By switching in synchronism with the switching of the operation state, image information corresponding to image shift can be read from the frame buffer (storage elements 72r, 72g, 72b), so that the circuit can be reduced in size without new calculation. Parts cost can be reduced.
[0140]
In the case of the present embodiment, as shown in FIG. 20, the control pattern of the EEPROM 74 referred to by the storage element control signal generation circuit 73 is directly switched by the optical path modulation means switching signal, and the frame buffers (storage elements 72r, 72g) are switched. , 72b) may be configured to switch the control signal generated. In this case, since the memory element control signal generation circuit 73 functions as a switching unit, the switching circuit (multiplexer) 75 can be omitted, and the number of parts can be reduced.
[0141]
Incidentally, as a comparative example, a configuration in which the optical path modulation means 14 reads out image information corresponding to each of the first and second operation states from the frame buffer, inputs the information to the subframe buffer, and switches the display according to the operation state. In this embodiment, the circuit scale is merely provided with a means for changing the address, whereas in the comparative example, the display capacity of each of the light valves 5r, 5g, 5b.times.2 times storage. The storage elements 72t, 72g, and 72b having a capacity are required, and a circuit for controlling the respective storage elements 72r, 72g, and 72b is required. In particular, the storage elements 72r, 72g, and 72b are required to operate at high speed. As a result, the cost of parts has increased significantly.
[0142]
An eighth embodiment of the present invention will be described with reference to FIG. This embodiment also shows an example of display data control means for controlling the writing of image information to each light valve 5r, 5g, 5b (31r, 31g, 31b).
[0143]
The display data control means of the present embodiment has a storage element (subframe memory) for storing image information for each subframe, and copes with it by adjusting the timing of a signal for controlling reading of this storage element. The pixel position of the image information written to the light valves 5r, 5g, and 5b to be controlled is controlled.
[0144]
That is, with respect to the address position of the pixel of the light valve 5g with respect to the color light having a polarization state different from that of the other color light, the light path modulation means 14 outputs the polarized light emitted from the light valve 5g with respect to the address position of the pixel of the other light valves 5r and 5b. When the image information is written in the pixel position shifted by n + 1 in the subframe acting on the optical path, and in the subframe in which the optical path modulator 14 does not act on the output polarized light of the light valve 5g, The data is shifted by adjusting the timing of the signal for controlling the reading.
[0145]
For comparison, a prototype was manufactured by adjusting the writing timing to the storage element. In this comparative example, since the same control signal is used for reading, an unshifted image is stored to shift the display signal. The storage element generates unnecessary storage capacity. On the other hand, in the present embodiment, since the read timing is adjusted, the necessary capacity can be used without wasting the storage capacity.
[0146]
Specifically, as a result of trial manufacture for the case of a light valve with a display capacity of 1024 × 768, in this embodiment, the memory element to be used is 1024 × 768 × 8 as shown on the leftmost side in FIG. Met. On the other hand, in the comparative example, since the timings are aligned at the time of input (writing), the address written to each memory element displayed at the same position on the screen between the memory elements displaying different colors. However, the storage element to be used is 1025 × 769 × 8 as shown at the center in FIG. 21 when the storage element used is shifted by one pixel.
[0147]
As a result of comparison, when a light valve having a display capacity of 1024 × 768 is used, the storage element capacity used is 2304 pixels (2304 bytes in terms of 24-bit color conversion) less than the comparative example in this embodiment. Become.
[0148]
Here, in general, the memory element is produced based on a fixed number of cells. 1024 × 768 × 24 = 188874368 and 18874368 = 1024 × 1024 × 18, and in the case of the present embodiment, a ready-made storage element can be used with a resolution that falls within the standard. However, in the comparative example, the number of pixels is larger than the XGA standard, but an off-the-shelf storage element cannot be used. In this case, since the storage elements are commercialized for each fixed capacity, it is necessary to store the image data across a plurality of storage elements even if the capacity is increased or the controllability is reduced.
[0149]
As shown in the rightmost part of FIG. 21, when using a ready-made memory element of SXGA (1280 × 1024) corresponding to one size upper standard, in order to ensure the same controllability, a capacity of about 60% is required. Either it is wasted and it corresponds to each light valve, or the controllability is extremely lowered, and the image data for three light valves is used by two storage elements. Again, about 10% capacity is not used. In the latter case, since data cannot be individually output to the light valve, it is necessary to operate at a higher speed than a normal storage element, resulting in a significant increase in cost.
[0150]
As described above, according to the present embodiment, the capacity of the storage element can be within the ready-made standard, and the shift of the image data can be realized without increasing the number of parts. In other words, the storage element can be configured with the minimum necessary capacity without waste by preparing a storage capacity corresponding to the required amount of image information.
[0151]
A ninth embodiment of the present invention will be described with reference to FIG. This embodiment also shows an example of the display data control means 81 that controls the writing of image information to each light valve 5r, 5g, 5b (may be 31r, 31g, 31b).
[0152]
As shown in FIG. 22, the display data control means 81 of the present embodiment has a function capable of adjusting the transfer timing of data input to the light valves 5r, 5g, 5b (31r, 31g, 31b). The provided control function circuits 82r, 82g, and 82b are integrally mounted on the substrates 83r, 83g, and 83b of the light valves 5r, 5g, and 5b. That is, the contents of the amount, direction, and timing of shifting the image information are set in advance by setting from the outside of the control function circuits 82r, 82g, and 82b. , 84g, 84b, and JTAG is used for updating data from the outside. In FIG. 22, 85 is a normal frame buffer (storage element) for storing image information for one screen, and 86 is a normal storage element control circuit for this frame buffer 85.
[0153]
More specifically, as the light valves 5r, 5g, 5b, a liquid crystal panel using ferroelectric liquid crystal is used for the function of performing light modulation. On the substrates 83r, 83g, 83b on which the liquid crystal panel is mounted, Control function circuits 82r, 82g, and 82b having functions of performing data input and display control to the liquid crystal panel are integrally manufactured.
[0154]
According to the present embodiment, by mounting the control function circuits 82r, 82g, and 82b having a function of adjusting the transfer timing of the data input to the light valves 5r, 5g, and 5b themselves, the memory element (frame As the buffer 85) and the storage element control circuit 86, those having a conventional configuration can be used, and it is possible to implement without changing or replacing the existing storage element or storage element control circuit. Yes, it is possible to reduce the cost of parts such as peripheral circuits.
[0155]
A tenth embodiment of the present invention will be described with reference to FIGS. This embodiment also shows an example of the display data control means 91 that controls the writing of image information to each light valve 5r, 5g, 5b (may be 31r, 31g, 31b).
[0156]
As shown in FIG. 23, the display data control means 91 of the present embodiment includes a frame buffer 92 as a storage element that stores image information for one screen, an output terminal of the frame buffer 92, and light valves 5r, 5g. , 5b, and a timing control means 93 that can adjust the data transfer timing. The timing control means 93 includes, for example, delay circuits 94r, 94g, 94b provided on each data line and a control circuit 95 that controls these delay circuits 94r, 94g, 94b.
[0157]
As shown in FIG. 24, the delay circuit 94 (94r, 94g, 94b) includes an input terminal Tin connected to the frame buffer 92 and an output terminal Tout connected to each light valve 5 (5r, 5g, 5b). A delay element 96 provided on the data line therebetween, a first switch 97 in parallel with the delay element 96, and a second switch 98 in series with the delay element 96 are configured. The delay element 96 is realized by, for example, an analog-controlled delay element (the delay amount is adjusted by a resistor and a capacitor capacity), and the first and second switches 97 and 98 are controlled to be opened and closed by the control circuit 95. 24. As shown in FIGS. 24A and 24B, they are complementary to each other so that when one is on, the other is off.
[0158]
With such a configuration, for example, when image data is delayed by one pixel, a delay circuit 94g is used to generate a delay corresponding to the control signal (as shown in FIG. 24B). The first switch 97 is turned off and the second switch 98 is turned off to pass the delay path of the delay element 96). Conversely, the image data is shifted by one pixel before the other signal lines. In this case, the remaining two lines of data are delayed by delay circuits 94r and 94b.
[0159]
According to the present embodiment, by providing the timing control means 93 with adjustable data transfer timing between the data input terminals of the light valves 5r, 5g, and 5b and the data output terminal of the frame buffer 92, the existing Shifting of image data can be realized while using the light valve 5r, 5g, 5b and the control system (existing control circuit 99) of the storage element (frame buffer 92) that does not consider the conventional data shift, These do not require new changes or replacements, and can be realized at low cost.
[0160]
The eleventh embodiment of the present invention will be described with reference to FIG. In this embodiment, instead of the delay circuit 94 (94r, 94g, 94b) in the display data control means 91 shown in the tenth embodiment, as shown in FIG. 25, each light valve 5 (5r, 5g, 5b), which are connected in series on the data line and have different delay amounts, for example, three delay elements 101, 102, 103, and delay elements 101 corresponding to the respective delay elements 101, 102, 103. , 102, and 103 are used, and a delay circuit 110 having a configuration including switching means using first switches 104, 105, and 106 and second switches 107, 108, and 109 for switching between bypassing and passing is used. The amount of delay in data transfer timing can be reduced by the combination of switching between the first switches 104, 105, 106 and the second switches 107, 108, 109. In which it was to be an integer.
[0161]
Here, the three delay elements 101, 102, and 103 are combined in such a manner that the delay amount is a power of 2, and the ratio of the delay amount of each delay element 101, 102, and 103 is 1: 2: 4. Yes. Each delay element 101, 102, 103 itself can use an element similar to the delay element 96. Further, the first switches 104, 105, 106 and the second switches 107, 108, 109 can also be configured by analog switches or the like as in the case of the switches 97, 98, and when one is on, the other is off. They are complementary to each other.
[0162]
In such a configuration, the delay amount shown in Table 1 can be obtained from the delay circuit 110 by the on / off switching combination of the switches 104 to 109 for the delay elements 101, 102, and 103. In Table 1, the case where the first switch side is OFF and the delay element is passed is indicated by ◯, the case where the second switch side is OFF and the delay element is bypassed is indicated by ×, and the delay amount is the delay of the delay element 101 The relative value with the amount set to 1 is shown.
[0163]
[Table 1]

[0164]
According to the present embodiment, fine delay amount control can be performed for each data line, and more appropriate display position control can be performed.
[0165]
A twelfth embodiment of the present invention will be described with reference to FIG. In the present embodiment, instead of the delay circuit 94 (94r, 94g, 94b) shown in the display data control means 91 of the tenth embodiment, as shown in FIG. A data line that passes through the delay element 111 and a data line that bypasses the delay element 111 are prepared for each of the light valves 5 (5r, 5g, 5b) based on a control signal from the control circuit 95. The delay circuit 113 is provided with a selector 112 as connection switching means for selectively switching whether to output data by the data line. As the delay element 111 itself, an element similar to the delay element 96 can be used. Although the number of control signals for the light valve 5 is large, only three signals are shown in FIG. 26 for simplicity of explanation.
[0166]
With such a configuration, the light valve 5 that requires a delay switches the selector 112 so that a signal that has passed through the delay element 111 is switched, and the light valve 5 that does not require a delay switches the selector 112 to the delay element 111. A signal that does not pass through can be input.
[0167]
Incidentally, the selector 112 is switched by using a 1-bit control terminal and switching the control terminal to the power supply voltage or the GND level.
[0168]
According to the present embodiment, it is possible to delay the signal only by switching the selector 112 and only the light valve 5 that requires a delay.
[0169]
A thirteenth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, instead of the analog-controlled delay element 96 in each of the delay circuits 94r, 94g, 94b of the display data control means 91 of the tenth embodiment, the delay amount can be controlled by digital processing. Latches 121r, 121g, and 121b as control delay elements are used as delay elements. The latch 121 has, for example, a flip-flop configuration, and a clock signal is used as a sampling signal as a reference signal. When data is delayed, a delay corresponding to the clock signal is generated by using the latch 121. . Conversely, when it is desired to shift before other data, data other than the data to be advanced may be delayed by the latch 121.
[0170]
FIG. 28 shows an operation example of the latch 121. A signal to be delayed is shown as an original signal, and a flip-flop that operates at the rising edge of the clock is used as the latch 121. The latch 121 is sampled every time the clock rises, and a delay occurs with respect to the original signal as shown in the delay signal.
[0171]
【Example】
Some examples configured according to the above-described embodiments will be listed below.
[0172]
[Example 1]
As a light valve 5r, 5g, 5b, a transmissive light valve having a pixel pitch of 14 μm and a pixel number of 1024 × 768 pixels using a ferroelectric liquid crystal is used, and a projection type image having an optical system configured as shown in FIG. A display device was produced. A 120 W high-pressure mercury lamp was used as the light source 1. A half-wave plate was used as the polarization rotation element 13 so that only green light was incident on the light valve 5g as s-polarized light. The F value of the illumination system was 2.8. The fly-eye lenses 2 and 3 are provided with polarization conversion elements (not shown), and the other color lights are incident on the light valves 5r and 5b as p-polarized light. The light valves 5r, 5g, and 5b are configured to rotate incident polarized light by 90 ° when they are turned on. As a result, the polarized light incident on the cross dichroic prism 7 is p for green and s polarized for other color light. did. The optical path modulation means 14 is a combination of a polarization modulation means 15 made of a ferroelectric liquid crystal element and an optical path deflection element 16 obtained by cutting lithium niobate in a direction of 45 ° with respect to the crystal axis. The retardation of the ferroelectric liquid crystal was 0.22 μm and the cone angle was 45 °. The polarization direction of the projection light is configured to coincide with or orthogonal to one of the bistable alignment directions of the ferroelectric liquid crystal, and the incident polarization is maintained when a negative voltage is applied, and the polarization plane of the incident polarization is maintained when a positive voltage is applied. Was configured to rotate 90 °. Thus, the polarization of the emitted light is switched between s-polarized light and p-polarized light by switching of the polarization modulation means 15 made of a ferroelectric liquid crystal element. The plate thickness of lithium niobate was 0.18 mm, and the tilt direction of the crystal axis was the direction of p-polarized light. The image light was enlarged and projected by the projection lens 8 to constitute a front projection type image display device.
[0173]
The polarization modulation means 15 composed of a ferroelectric liquid crystal element is operated at 120 Hz, and two subframes having two different shift directions are configured by shifting the drive timing. The writing image information of the light valves 5r, 5g, and 5b and the polarization modulation means 15 were controlled for each subframe. When a negative voltage is applied to the polarization modulation means 15 composed of a ferroelectric liquid crystal element, image information of even lines is displayed in the green light valve 5g as shown in FIG. 7 (c '), and blue and red light valves. The image information of odd lines is written in 5b and 5r as shown in FIG. On the other hand, when a positive voltage is applied to the polarization modulation means 15 made of a ferroelectric liquid crystal element, the image information of odd lines is applied to the green light valve 5g, and the blue and red light valves 5b, 5r. The image information of even lines is written in.
[0174]
When the image display apparatus of this embodiment having such a configuration is operated, high-speed modulation is possible between the display shifted by a horizontal half pitch with respect to the original image and the display of the original image by the action of the optical path modulation means 14. Thus, a high-resolution display of 1024 × 1536 pixels with no pixel shift between subframes can be performed. Also, almost no color unevenness was observed in the image. Accordingly, no color shift is observed in the projected image by this image display apparatus, and a good display can be performed.
[0175]
[Example 2]
In the first embodiment, polarization of only green light incident on the dichroic prism 7 is reversed by inverting the on / off state of image information written to the green light valve 5g without using the polarization rotation element 13 for rotating the polarization of illumination light. Is p, and other colors are s-polarized light. Other than that, the optical system was configured in the same manner as in Example 1 and operated in the same manner.
[0176]
When the image display apparatus of this embodiment having such a configuration is operated, high-speed modulation is possible between the display shifted by a horizontal half pitch with respect to the original image and the display of the original image by the action of the optical path modulation means 14. Thus, a high-resolution display of 1024 × 1536 pixels with no pixel shift between subframes can be performed. Also, almost no color unevenness was observed in the image. Accordingly, no color shift is observed in the projected image by this image display apparatus, and a good display can be performed.
[0177]
[Example 3]
In the second embodiment, the half-wave plate 17 is provided immediately after the optical path modulation means 14 (14x) so that the polarization plane of the outgoing light is rotated by 90 °, and the optical path modulation means 14y is also provided on the outgoing side. The configuration is as shown in FIG. The optical path modulation unit 14y is configured in the same manner as the optical path modulation unit 14x, but is configured so that the tilt direction of the crystal axis of lithium niobate as the optical path deflection element 16y is orthogonal to the optical path deflection element 16x. With such a configuration, it is possible to shift the optical path in four vertical and horizontal directions. The image light was enlarged and projected by the projection lens 8 to constitute a front projection type image display device.
[0178]
The polarization modulation means 15x and 15y by the two ferroelectric liquid crystal elements of the respective optical path modulation means 14x and 14y operate at 120 Hz, respectively, and by shifting the drive timing, four sub-types having four different shift directions are different. Configured the frame. The writing image information of the light valves 5r, 5g and 5b and the polarization modulation means 15x and 15y were controlled for each subframe. When a negative voltage is applied to the ferroelectric liquid crystal, the green light valve 5g has even line image information as shown in FIG. 7C ', and the blue and red light valves 5b and 5r have image information. As shown in FIG. 7A ', image information of odd lines was written. When a positive voltage is applied to the ferroelectric liquid crystal, odd line image information is written in the green light valve 5g, and even line image information is written in the blue and red light valves 5b and 5r. .
[0179]
When the image display apparatus of this embodiment having such a configuration is operated, high-speed modulation is performed between the display shifted from the original image by half the vertical and horizontal pitches by the action of the optical path modulation means 14x and 14y and the display of the original image. Thus, a high-resolution display of 2048 × 1636 pixels with no pixel shift between subframes can be performed. Also, almost no color unevenness was observed in the image. Accordingly, no color shift is observed in the projected image by this image display apparatus, and a good display can be performed.
[0180]
[Example 4]
In the third embodiment, as shown in FIG. 12, the pixel position of the green light valve 5g is shifted from the pixel positions of the other light valves 5r and 5b by ½ pitch of the pixels. Pixels that are simultaneously written to the light valves 5r, 5g, and 5b are either even lines or odd lines of display data. When a negative voltage is applied to the ferroelectric liquid crystal element which is the polarization modulation means 15, writing is performed on the green light valve 5g at a pixel position shifted by a half pitch with respect to the optical path shift direction (the pixel in FIG. 12). When applying a positive voltage to the ferroelectric liquid crystal element, the pixel position (5gp2) shifted by a half pitch in the direction opposite to the optical path shift direction was controlled.
[0181]
By such writing control, red, blue and green image lights are projected at the same position, and are shifted by the half pitch of the pixel by switching of the ferroelectric liquid crystal element which is the polarization modulation means 15.
[0182]
When the image display apparatus of this embodiment having such a configuration is operated, high-speed modulation is possible between the display shifted by a horizontal half pitch with respect to the original image and the display of the original image by the action of the optical path modulation means 14. Thus, a high-resolution display of 1024 × 1536 pixels with no pixel shift between subframes can be performed. Also, almost no color unevenness was observed in the image. Accordingly, no color shift is observed in the projected image by this image display apparatus, and a good display can be performed.
[0183]
[Example 5]
A projection-type image display device was manufactured by the optical system shown in FIG. As the illumination system, the illumination device 12 including the light source 1 and the integrator optical system 4 similar to those in Example 1 was used. As the wavelength-selective retardation plate 43, a green / magenta filter manufactured by Color Link was used, and only green polarized light was converted to p-polarized light. As the light valves 31r, 31g, and 31b, reflective light valves having a pixel pitch of 14 μm and a number of pixels of 1024 × 768 pixels were used.
[0184]
With the configuration of this embodiment, the p-polarized light is illuminated on the green light valve 31g, and the s-polarized light is illuminated on the blue and red light valves 31b and 31r. Since the light valves 31r, 31g, and 31b act so as to rotate the light corresponding to the ON pixel by 90 °, green light is emitted as s-polarized light and blue and red as p-polarized light.
[0185]
When the image display apparatus of this embodiment is operated in the same manner as the embodiment 1 with respect to the method of writing image information to the light valves 31r, 31g, and 31b, the optical path modulation means 14 causes the horizontal half-pitch of the original image. High-speed modulation is possible between the shifted display and the display of the original image, and a high-resolution display of 1024 × 1536 pixels without pixel shift can be performed. Also, almost no color unevenness was observed in the image. Accordingly, no color shift is observed in the projected image by this image display apparatus, and a good display can be performed.
[0186]
[Example 6]
In the fifth embodiment, the pixel position of the green light valve 31g is shifted by a half pitch with respect to the pixel positions of the other light valves 31r and 31b, and the operation method is the same as in the fourth embodiment.
[0187]
The image display apparatus of this embodiment can perform high-speed modulation between the display shifted by a horizontal half pitch with respect to the original image and the display of the original image by the action of the optical path modulation means 14, and is 1024 × without pixel shift. The high-resolution display of 1536 pixels could be performed. Also, almost no color unevenness was observed in the image. Accordingly, no color shift is observed in the projected image by this image display apparatus, and a good display can be performed.
[0188]
【The invention's effect】
According to the first aspect of the present invention, the polarization state of at least one color among the plurality of image lights incident on the color composition unit is different from the polarization state of the other color light, which is caused by the incident angle dependency of the color composition unit. An image display apparatus capable of suppressing display unevenness or performing high-efficiency color composition is provided with an optical path modulation means for modulating the optical path of the synthesized image light, and writing to each light valve during an image frame period As a display image, high resolution display without color misregistration is performed by writing image information at a display position corresponding to an optical path shift amount corresponding to a polarization state depending on an operation state of the optical path modulation unit during the image frame period. Can be made.
[0189]
According to the second aspect of the present invention, in the image display device according to the first aspect, the polarization state of the image light is linearly polarized and the difference in polarization state is orthogonal, so that the optical path shift amount becomes clear and the light It is possible to appropriately cope with the correction of the writing position of the image information with respect to the bulb, and it is possible to display a high-resolution image without any pixel position shift caused by the shift by the optical path modulation means.
[0190]
According to a third aspect of the present invention, in the image display device according to the first or second aspect, the image information of the display position corresponding to the optical path shift amount corresponding to the polarization state according to the operational state of the optical path modulation means in the image frame period is obtained. A specific information writing method of the writing configuration is clarified, and display with high resolution without color misregistration is possible.
[0191]
According to invention of Claim 4, in the image display apparatus of Claim 1 or 2, it becomes realizable with a simpler information writing method in addition to a display with high resolution.
[0192]
According to the fifth aspect of the invention, in the image display device according to the fourth aspect, in addition to the display with high resolution, a simpler and more specific information writing method becomes clear.
[0193]
According to the sixth aspect of the present invention, in the image display device according to the fourth or fifth aspect, the optical configuration and the information writing method are most simple when n = 0, and the peripheral display area can be most effectively utilized. It becomes.
[0194]
According to the seventh aspect of the present invention, in the image display device according to any one of the first to sixth aspects, since the data is updated without having a storage element such as a subframe buffer for each light valve, a high-speed response is provided. Therefore, the number of components such as storage elements and control circuits that are required can be reduced, and the cost can be reduced. Further, by securing a separate storage area for each light valve, each color can be easily controlled, and the control circuit can be reduced in size and the number of parts can be reduced.
[0195]
According to an eighth aspect of the present invention, in the image display device according to any one of the first to sixth aspects, a transfer storage means is provided between each light valve and a storage element for storing image information of one screen. As a result, the data transfer speed of the storage element such as the frame buffer is reduced, and the component cost and the stable operation are realized. At this time, unlike the case of the subframe buffer, the transfer cost is reduced by using the transfer storage element having a capacity smaller than the number of pixels of the light valve and also using the period of the control signal. Stable operation is ensured with the reduction of the above.
[0196]
According to the ninth aspect of the invention, in realizing the image display device according to the third aspect, two or more types of image information reading methods are defined in advance and set and held in the reading method holding unit. By switching the method corresponding to the switching of the first and second operation states of the optical path modulation means, it is possible to read out image information corresponding to the image shift from the storage element. It is possible to reduce the size and the cost of parts.
[0197]
According to the invention of claim 10, in realizing the invention of claim 5, the storage element prepares a storage capacity corresponding to a necessary amount of image information, so that the storage capacity can be minimized without waste. It is possible to configure with a capacity.
[0198]
According to the eleventh aspect of the present invention, in the image display device according to any one of the first to sixth aspects, a function of adjusting a transfer timing of image information data input to each light valve itself is provided. By implementing the display data control means, it is possible to input image information data to the light valve while using the existing storage element and its control circuit, and to reduce the cost of components such as peripheral circuits. it can.
[0199]
According to the twelfth aspect of the present invention, in the image display device according to any one of the first to sixth aspects, the data transfer timing can be adjusted between the input terminal of the light valve and the output terminal of the storage element. By providing the control means, it is possible to shift the image information while using the existing light valve and the control structure of the storage element that does not take into account the shift of the image information. As a result, cost reduction can be realized.
[0200]
According to the thirteenth aspect, the image display device according to the twelfth aspect can be easily realized by using a delay element as the timing control means.
[0201]
According to the fourteenth aspect of the invention, in realizing the image display device according to the twelfth aspect, the delay amount can be controlled in multiple stages, and appropriate display position control can be performed.
[0202]
According to the fifteenth aspect of the present invention, in realizing the image display device according to the twelfth aspect, the signal can be delayed only by the light valve that requires a delay and only by switching the connection switching means.
[0203]
According to the sixteenth aspect of the invention, in realizing the image display device according to any one of the thirteenth to fifteenth aspects, since it is stable with respect to temperature, variation at the time of setting, and readjustment is unnecessary. Therefore, delay control with excellent controllability is possible.
[0204]
According to the seventeenth aspect of the present invention, in the image display device according to any one of the first to sixteenth aspects, it is possible to provide a suitable example of the color composition means. In particular, when a dichroic prism is used, the wavelength shift of the combined light occurs due to the incident angle characteristics of the illumination light, and the display tends to cause color unevenness, but a plurality of image light incident on the color combining means is likely to occur. By making the polarization state of at least one of the colors different from the polarization state of the other color light, it is possible to suppress display unevenness due to the incident angle dependency of the color synthesis means, and to perform highly efficient color synthesis. The image information written to each light valve during the image frame period is configured to write the image information at the display position corresponding to the optical path shift amount according to the polarization state according to the operating state of the optical path modulation means during the image frame period. Therefore, it is possible to perform display with high resolution without color misregistration.
[0205]
According to the eighteenth aspect, a more specific configuration example of the image display device according to the seventeenth aspect is clarified.
[0206]
According to the nineteenth aspect of the present invention, in the image display device according to the seventeenth or eighteenth aspect, the polarization state of at least one of the plurality of image lights incident on the color combining means is different from the polarization state of the other color light. A specific example can be provided.
[0207]
According to the twentieth aspect, in the image display device according to the seventeenth or eighteenth aspect, the polarization state of at least one of the plurality of image lights incident on the color synthesizing unit is different from the polarization state of the other color light. A simple and efficient specific example can be provided.
[0208]
According to the twenty-first aspect, in the image display device according to any one of the first to sixteenth aspects, a suitable example of the color synthesizing means can be provided. In particular, in the synthesis by the polarization beam splitter, two types of polarized light having different polarization states of the combined light are mixed, but the display position corresponding to the optical path shift amount according to the polarization state depending on the operation state of the optical path modulation means in the image frame period. With the configuration in which the image information is written, even when the optical path modulation means is provided, it is possible to perform display with high resolution without pixel shift due to color.
[0209]
According to the twenty-second aspect of the invention, it is possible to provide a compact and highly efficient optical system configuration for realizing the twenty-first aspect of the invention.
[0211]
Claim 23 According to the described invention, Claim 1 In realizing the described invention, a suitable example of an optical path deflecting element can be provided.
[0212]
Claim 24 According to the described invention, Claim 23 In the image display apparatus described above, by using a liquid crystal element composed of ferroelectric liquid crystal having a high response speed, an operation for switching incident polarized light to two polarization states having orthogonal polarization planes at high speed can be realized with high responsiveness.
[0213]
Claim 25 According to the described invention, Claim 23 or 24 In the image display device described above, a preferable configuration example can be provided by using a lithium niobate crystal having excellent stability, cost, and transparency as the uniaxial optical anisotropic body.
[0214]
Claim 26 According to the described invention, Claims 1 to 25 In the image display device according to any one of the above, since optical path modulation can be performed two-dimensionally, higher resolution can be obtained.
[0215]
Claim 27 According to the described invention, Claims 1 to 26 In the image display device according to any one of the above, a preferable configuration example can be provided by using a liquid crystal display element made of ferroelectric liquid crystal that operates digitally as a light valve.
[0216]
Claim 28 According to the described invention, Claims 1 to 26 In the image display device according to any one of the above, by using a liquid crystal display element made of antiferroelectric liquid crystal having excellent response speed as a light valve, a suitable configuration example suitable for halftone expression can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an optical system configuration of an entire image display apparatus according to a first embodiment of the present invention.
FIG. 2 is a side view for explaining an example of the principle configuration of the optical path modulation means and its operation.
FIG. 3 is a schematic diagram showing image information and a display image for explaining the operation of the optical path modulation means.
FIG. 4 is a schematic diagram showing image information and a display image for explaining a defect due to a simple optical path shift.
FIG. 5 is a schematic diagram showing a display example of the composite image.
FIG. 6 is an explanatory diagram showing the principle of a method for writing image information to the light valve of the present embodiment in comparison with a conventional method.
FIG. 7 is a schematic diagram showing image information and a display image when the image information writing method of the present embodiment is used.
FIG. 8 is a block diagram showing an example of a configuration of display data control means.
FIG. 9 is a block diagram illustrating a configuration example of a corresponding conventional method.
FIG. 10 is an explanatory diagram showing the principle of a method for writing image information to a light valve in the case of a two-dimensional shift as a modification.
FIGS. 11A and 11B are a side view and a plan view for explaining an example of the principle configuration of the optical path modulation means in the two-dimensional case and its operation. FIGS.
FIG. 12 is a side view for explaining an example of the basic configuration of the optical path modulation means and the like according to the second embodiment of the present invention and its operation.
FIG. 13 is a schematic diagram showing the image information and the display image.
FIG. 14 is a configuration diagram showing an optical system configuration of the entire image display apparatus according to the third embodiment of the present invention.
FIG. 15 is a configuration diagram showing the vicinity of a polarization beam splitter in an image display device according to a fourth embodiment of the present invention.
FIG. 16 is a configuration diagram showing the vicinity of a polarization beam splitter in an image display device according to a fifth embodiment of the present invention.
FIG. 17 is a block diagram illustrating a configuration example of display data control means according to a sixth embodiment of the present invention.
FIG. 18 is a time chart showing an example of the data transfer control in comparison with the conventional method.
FIG. 19 is a block diagram showing a configuration example of display data control means according to a seventh embodiment of the present invention.
FIG. 20 is a block diagram showing a modified example thereof.
FIG. 21 is an explanatory diagram relating to the storage capacity according to the eighth embodiment of this invention;
FIG. 22 is a block diagram showing a configuration example of display data control means according to the ninth embodiment of the present invention.
FIG. 23 is a block diagram illustrating a configuration example of display data control means according to the tenth embodiment of the present invention.
FIG. 24 is a block diagram illustrating a configuration example of the delay circuit.
FIG. 25 is a block diagram showing a configuration example of a delay circuit in the eleventh embodiment of the present invention.
FIG. 26 is a block diagram showing a configuration example of a delay circuit in a twelfth embodiment of the present invention.
FIG. 27 is a block diagram illustrating a configuration example of display data control means according to the thirteenth embodiment of the present invention;
FIG. 28 is a timing chart showing an example of the latch operation.
FIG. 29 is a configuration diagram showing an optical system configuration of the entire conventional image display apparatus.
FIG. 30 is a side view for explaining the principle of the optical path shift.
FIG. 31 is a configuration diagram showing an optical system configuration of an entire three-plate optical system type image display apparatus.
FIG. 32 is an operation explanatory diagram for describing an operation when a pixel shift method is applied;
[Explanation of symbols]
5r, 5g, 5b Light valve, liquid crystal display element
7 Cross dichroic prism, color composition means
8 Lens
12 Lighting equipment
13 Polarization rotating means
14 Optical path modulation means
15 Polarization modulation means
16 Optical path deflecting element
17 Polarization plane rotating means
21 Display data control means
22r, 22g, 22b Storage element, storage area
24 Control circuit
31r, 31g, 31b Light valve
33 Polarization rotating means
41 Polarizing beam splitter
42 Polarization separation element
51 Polarizing beam splitter
61 Display data control means
62 Memory element
63r, 63g, 63b Transfer memory element
71 Display data control means
72r, 72g, 72b Memory element
74 Reading method holding means
75 switching means
81 Display data control means
83r, 83g, 83b substrate
85 memory elements
91 Display data control means
92 Memory elements
93 Timing control means
94 Delay circuit
96 delay elements
101-103 delay element
104-109 switching means
110 Delay circuit
111 Delay element
112 Connection switching means
113 Delay circuit
121 Digitally controlled delay element

Claims (28)

Multiple light valves for image modulation;
Display data control means for controlling writing of image information to these light valves;
An illumination device that illuminates each light valve with a different color light;
Color synthesizing means for synthesizing image light modulated by the light valves;
Optical path modulation means for modulating the optical path of the combined image light in time division in synchronization with the image modulation of the light valve;
A lens that magnifies and displays the combined image light;
With
The plurality of image lights incident on the color combining means have two polarization states having different polarization directions for one color light and another color light,
The optical path modulation unit is one of a polarization modulation unit that switches a polarization plane of the image light between the two polarization states, and an output light of the two polarization states emitted from the polarization modulation unit. An optical path polarizing element that bends the optical path with respect to the outgoing light in the polarization state, and changes the display position of the display image of the light valve between at least two states to display the image whose display position is changed. Superimpose by dividing,
The display data control means writes the image information of the display position corresponding to the optical path shift amount of each polarized light according to the operation state of the optical path modulation means during the image frame period as a display image to be written to each light valve during the image frame period. An image display device.   The image display apparatus according to claim 1, wherein the polarization of the image light incident on the color combining unit is linearly polarized light, and incident light having a different polarization state has a polarization direction orthogonal to other incident light.   The display data control means has a second action on the light valve for the color light having a polarization state different from that of the other color light during the image frame period in which the optical path modulation means is in the first action state. Image information corresponding to the display position in the state, and image information corresponding to the display position in which the other color is in the first action state during the image frame period in which the optical path modulator is in the second action state. The image display device according to claim 1 or 2, wherein the image is written. The light valve for color light having a polarization state different from that of other color light is
When the optical path shift amount by the optical path modulation means is s, the pixel pitch of the light valve is p, and the integer is n,
The image display device according to claim 1, wherein the pixel position is arranged so as to be shifted in a shift direction of the optical path by a distance corresponding to p * (n + s) with respect to the pixel position of the other light valve.   The display data control means is configured such that the light path modulation element is connected to the address position of the pixel of the other light valve as the address position of the pixel of the light valve with respect to the color light having a polarization state different from that of the other color light. The image information is written at a pixel position shifted by n in a sub-frame that acts on outgoing polarized light and by n + 1 in a sub-frame in which the optical path modulation element does not act on outgoing polarized light of the light valve. 4. The image display device according to 4.   6. The image display device according to claim 4, wherein n = 0.   The display data control means includes a storage element having a capacity for storing image information for one screen and a storage area corresponding to the amount of image data of each color for each light valve, and the storage element. A control circuit that controls writing to and reading from each storage area of the storage element so that at least only necessary data is read and written to each light valve in order to superimpose in time when reading image information The image display device according to claim 1.   The display data control means is a storage element that stores image information for one screen, and is provided between the storage element and each of the light valves, and is capable of writing and reading with a capacity smaller than the number of pixels of the light valve. An image display device according to claim 1, further comprising: a transfer storage element that operates asynchronously.   The display data control means reads out from the same storage element the storage element that stores image information for one screen and the image information corresponding to the display position in the first operation state and the second operation state. 4. A reading method holding unit in which at least two types of reading methods are set, and a switching unit for switching the reading method set in the reading method holding unit when reading image information from the storage element. Image display device.   The display data control means has a storage element for storing image information for each subframe, and image information to be written to the corresponding light valve by adjusting the timing of a signal for controlling the reading of the storage element. The image display device according to claim 5, wherein the pixel position is controlled.   The image display device according to claim 1, wherein the display data control unit has a function of adjusting a transfer timing of input data and is integrally mounted on a substrate of each light valve. .   The display data control means is a storage element that stores image information for one screen, and is provided between the output terminal of the storage element and the input terminal of the light valve, and is capable of adjusting the data transfer timing. And an image display device according to any one of claims 1 to 6.   The image display device according to claim 12, wherein the timing control unit includes a delay element that selectively delays a data transfer timing to the light valve by a set time.   The timing control unit is configured to switch a plurality of delay elements connected in series on the data line to the light valve and having different delay amounts, and whether the delay elements corresponding to each delay element are routed or bypassed. 13. The image display device according to claim 12, further comprising: means for adjusting a delay amount of data transfer timing by a combination of switching of the switching means.   The timing control means includes: a delay element that delays a data transfer timing to the light valve by a set time; a data line that passes through the delay element with respect to the light valve; and a data line that bypasses the delay element The image display apparatus according to claim 12, further comprising: a connection switching unit that selectively switches a connection with the display.   16. The image display device according to claim 13, wherein a digitally controlled delay element capable of controlling a delay amount by digital processing controlled based on a reference signal is used as the delay element.   The image display device according to claim 1, wherein the color synthesizing unit includes a dichroic prism.   18. The image display device according to claim 17, wherein the color synthesizing means is a cross dichroic prism, and the polarized light incident on the color synthesizing means is only green light as p-polarized light and the other red light and blue light are s-polarized light.   The polarization state of at least one of the plurality of image lights incident on the color composition unit is different from the polarization state of the other color light by providing a polarization rotation unit in the illumination optical path of the illumination device. Image display device.   19. The polarization state of at least one of the plurality of image lights incident on the color composition unit is different from the polarization state of the other color light by inverting on / off of image information to be written to the light valve. The image display device described.   The image display device according to claim 1, wherein the color synthesizing unit includes a polarization beam splitter.   The color synthesizing unit includes a polarization rotation unit that converts the polarization direction of specific color light into an orthogonal polarization direction, a polarization separation element that separates an optical path of the illumination light emitted from the polarization rotation unit by polarization, and the polarization separation element. The image display apparatus according to claim 21, further comprising: a polarization beam splitter that synthesizes outgoing light beams that are separated and modulated by the light valves and output. The polarization modulation means is a liquid crystal element, and the optical path deflecting element is opposite to the optical axis. The image display device according to claim 1, wherein the image display device is a uniaxial optical anisotropic body having an inclined main optical axis. 24. The image display device according to claim 23, wherein the liquid crystal element as the polarization modulation means is a ferroelectric liquid crystal element. The image display device according to claim 23 or 24, wherein the uniaxial optical anisotropic body as the optical path deflecting element is made of a lithium niobate crystal. The image display device according to any one of claims 1 to 25, further comprising: a plurality of the optical path modulation units having different directions in which the optical path is bent or shifted, and a polarization plane rotation unit provided on the optical path between the optical path modulation units. . 27. The image display device according to claim 1, wherein the light valve is a liquid crystal display element using a ferroelectric liquid crystal. 27. The image display device according to claim 1, wherein the light valve is a liquid crystal display element made of antiferroelectric liquid crystal.

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