JP2004184522A - Optical path deflector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To speed up an optical path shifting motion by an optical deflector whose configuration is facilitated and to improve reliability by suppressing occurrence of an alignment defect caused by repeated use. <P>SOLUTION: In the optical path deflection element 1, a liquid crystal layer 5, which is filled between a pair of transparent substrates 2, 2 with homeotropic alignment layers 3 on the insides thereof and forms a homeotropically aligned chiral smectic C phase, is made to contain a monomer etc. of a polymer material and is maintained at a temperature of smectic A phase formation of the liquid crystal layer 5 so as to control the molecular orientation. Furthermore, after a fibrous or network texture 5b composed of the polymer material is formed by photopolymerization, the liquid crystal layer is cooled to a temperature of chiral smectic C phase formation. Thereby disturbance of liquid crystal molecules does not occur even when the liquid crystal layer 5 is thick. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００７７】
（１）式中、Ｘは水素原子又はメチル基を表し、ｎは０又は１の整数を表し、６員環Ａ、Ｂ及びＣはそれぞれ独立的に、（２）式に示す構造のいずれかを表す。
【００７８】
【化２】

【００７９】
ｍは１〜４の整数を表し、Ｙ^１及びＹ^２はそれぞれ独立的に、単結合、−ＣＨ_２ＣＨ_２−、−ＣＨ_２Ｏ−、−ＯＣＨ_２−、−ＣＯＯ−、−ＯＣＯ−、−Ｃ≡Ｃ−、−ＣＨ＝ＣＨ−、−ＣＦ＝ＣＦ−、−（ＣＨ_２）_４−、−ＣＨ_２ＣＨ_２ＣＨ_２Ｏ−、−ＯＣＨ_２ＣＨ_２ＣＨ_２−、−ＣＨ＝ＣＨ−ＣＨ_２ＣＨ_２−、−ＣＨ_２ＣＨ_２−ＣＨ＝ＣＨ−を表し、Ｙ^３は単結合、−Ｏ−、−ＣＯＯ−、−ＯＣＯ−を表し、ａおよびｂは１〜２０の整数を表す。
好ましい例としては、下記の構造式（３）のようなものがあげられる。
【００８０】
【化３】

【００８１】
このような液晶性ジ（メタ）アクリレートは重合すると三次元網目構造を形成し、液晶層の配向状態を効果的に安定化することが出来る。例えば、キラルスメクチックＣ相を形成可能な液晶の中でも、特にチルト角と自発分極が大きく、配向安定性が悪いが高速応答性に優れた液晶と組み合わせることで、配向性と応答性を両立した光路偏向素子が得られる。
【００８２】
本発明の第８の形態では、モノマーが、液晶骨格と一つのアクリロイルオキシ基の間にメチレンスペーサーを有する液晶性アクリレート、または液晶性メタアクリレートを含有する。ここでは、両者を合せて液晶性（メタ）アクリレートと表記する。メチレンスペーサーを有する液晶性（メタ））アクリレートは重合すると側鎖型の液晶ポリマーを形成する。
液晶性（メタ）アクリレートとしては、下記の一般式（４）のような材料を用いることが出来る。
【００８３】
【化４】

【００８４】
（４）式中、Ｚは水素原子、ハロゲン原子、シアノ基、炭素原子数１〜２０のアルキル基又は炭素原子数２〜２０のアルケニル基を表し、その他の記号は（１）式で示した記号と同じ定義である。
好ましい例としては、下記の構造式（５）のようなものがあげられる。
【００８５】
【化５】

【００８６】
このような材料は、液晶骨格がメチレンスペーサーを介して高分子主鎖に結合するため液晶骨格が比較的動きやすく、配向状態の安定化効果は比較的弱いものの、液晶の反転動作に対する抵抗力が小さく応答性の劣化が少ないという利点がある。例えば、キラルスメクチックＣ相を形成可能な液晶の中でも、特にチルト角と自発分極が小さく、配向安定性は比較的良いが応答性が並の液晶と組み合わせることで、配向性と応答性を両立した光路偏向素子が得られる。
【００８７】
本発明の第９の形態では、モノマーが、液晶骨格と１つのアクリロイルオキシ基の間に、メチレンスペーサーが無い液晶性（メタ）アクリレートを含有する。液晶性（メタ）アクリレートとしては、下記の一般式（６）のような材料を用いることが出来る。
【００８８】
【化６】

【００８９】
（６）式中の各記号は（４）式に示した記号と同じ定義である。
特に、一般式（６）において、Ｘは水素原子を表し、ｎは０を表し、６員環Ａ及びＣはそれぞれ独立的に１，４−フェニレン基、又は１，４−トランスシクロヘキシル基を表し、Ｙ^１は単結合又は−Ｃ≡Ｃ−を表し、Ｙ^３は単結合を表し、Ｚはハロゲン原子、シアノ基又は炭素原子数１〜２０のアルキル基を表す材料が好ましい。
【００９０】
また、さらに好ましい例として下記の構造式（７）や（８）のようなものがあげられる。また、これらの混合物を用いても良い。例えば（７）と（８）を５０重量部づづ混合したものは、室温下でネマチック相を示し、扱いやすい。
【００９１】
【化７】

【００９２】
【化８】

【００９３】
このようなメチレンスペーサーが無い液晶性（メタ）アクリレートは、重合すると液晶骨格が高分子主鎖に直接結合するため、液晶骨格の動きが制限され、液晶骨格が配向安定性に直接寄与する。配向安定性は比較的強いが、高分子鎖自体にも動きやすさがあるため、配向状態の安定化効果は比較的強いものの、液晶の反転動作に対する抵抗力も比較的小さく、応答性の劣化が少ないという利点がある。例えば、キラルスメクチックＣ相を形成可能な液晶の中でも、特に配向安定性と応答性が悪い液晶と組み合わせることで、配向性と応答性を両立した光路偏向素子が得られる。
【００９４】
以上の第１から第９の実施形態では、光路の偏向方向、すなわち電界印加時の液晶分子の傾斜方向に平行な偏光方向、の直線偏光のみが光路の偏向を受け、これに直交した直線偏光はそのまま直進する。したがって、無偏光の光を入射した場合、出射光には偏向を受けない成分を含むため、光路偏向の有無に対するコントラストが低下してしまう。
【００９５】
図４は光路偏向素子への入射光の偏光方向を特定の方向に規制する手段を有する光路偏向装置の概要を示す図である。
同図において、符号８は直線偏光板を示す。
本発明の第１０の実施形態では、図４に示すように光路偏向素子への入射光の偏光方向を、液晶層内にかける電界の方向と直交する方向に設定する偏光方向規制手段を設ける。言い換えれば、光路偏向のシフト方向と平行な方向に直線偏光させる制御手段を設ける。偏光方向規制手段としては、直線偏光板８を用いることが出来る。直線偏光板８の偏光方向を電極４の長手方向に平行に合わせて、光路偏向素子１の入射面側に設置する。入射光が無偏光の場合でも、液晶分子の傾斜による光路偏向作用を受けない光成分をカットするので、確実に光路偏向による光スイッチングを行うことが出来る。
【００９６】
図５は光路偏向素子の組み合わせによる４方向シフト装置の構成を説明するための概略図である。
同図において、符号９は４方向シフト装置、１０は第１の光路偏向素子、１１は２分の１波長板、１２は第２の光路偏向素子をそれぞれ示す。
本発明の第１１の実施形態を図５に基づいて説明する。本実施形態は、前述した実施形態のように構成された光路偏向装置に、もう一つの光路偏向素子をシフト方向を変えて組み合わせた装置である。両光路偏向素子の間には偏光面回転手段としての２分の１波長板を挟んである。図５では、スペーサー、配向膜などは省略してある。
【００９７】
第１、第２光路偏向素子１０、１２は、各々の電極対４、４による電界発生方向を直交させて光進行方向に直列に配列されており、これらの両光路偏向素子間に偏光面回転手段として１／２波長板１１が配設されている。ここでは、電界発生方向が直交している例を図示しているが、直交に限らず所定の角度に設定しても良い。
１／２波長板１１は通常市販されている結晶板や液晶フィルムなど可視光用のものをそのまま適用できる。また、ツイストネマチック（以後ＴＮと略記する）液晶セルを用いて、偏光面を回転させることも出来る。
【００９８】
あらかじめ直線偏光に揃えられた光束Ｌは、光進行方向に対して前段側の第１光路偏向素子１０において偏向を受け左右２方向Ｌ１、Ｌ２のいずれかの光路を経た後、１／２波長板１１によって偏光方向を９０°回転させられて上下方向の偏光方向となることで、後段の第２光路偏向素子１２で偏向を受け、Ｌ１は上下２方向Ｌ１１、Ｌ１２のいずれかの光路をとり、また、Ｌ２も上下２方向Ｌ２１、Ｌ２２のいずれかの光路をとることにより、結果として４方向のいずれか１つの光路を通ることになる。
ここでは、偏向方向が９０°回転された例を図示しているが、９０°に限らず、第１光路偏向素子から出射した偏光方向を、第２光路偏向素子での偏向方向に一致させる所定の角度としても良い。
【００９９】
図６は４方向シフト装置の駆動の一例を示すタイミングチャートである。
図６（ａ）は第１光路偏向素子の駆動タイミング、図６（ｂ）は第２光路偏向素子の駆動タイミングを示す図である。両者を図示のようにタイミングを合わせることにより、４方向のシフトを一方向まわりに順次選択していく。
【０１００】
図７は光路偏向素子を用いた画像表示装置の概要図である。
同図において符号２１は光源としてのＬＥＤランプ、２２は拡散板、２３はコンデンサレンズ、２４は画像表示素子としての透過型液晶パネル、２５は投影レンズ、２６はスクリーン、２７は光源ドライブ部、２８は透過型液晶パネルのドライブ部、２９は光路偏向手段、３０は４方向シフト装置のドライブ部をそれぞれ示す。
本発明の第１２の実施形態を図７に基づいて説明する。本実施形態は、画像表示装置への適用例を示す。図７において、２次元アレイ状に配列した光源ＬＥＤランプ２１からスクリーン２６に向けて発せられる光の進行方向には、拡散板２２、コンデンサレンズ２３、画像表示素子としての透過型液晶パネル２４、画像パターンを観察するための光学部材としての投影レンズ２５が順に配設されている。
【０１０１】
透過型液晶パネル２４と投影レンズ２５との間の光路上にはピクセルシフト素子として機能する４方向シフト装置２９が介在されており、ドライブ部３０に接続されている。このような光路偏向手段２９として、前述したような４方向シフト装置等が用いられる。
【０１０２】
光源ドライブ部２７で制御されて光源３１から放出された照明光は、拡散板２２により均一化された照明光となり、コンデンサレンズ２３により液晶ドライブ部２８で照明光源２１と同期して制御されて透過型液晶パネル２４を照明する。この透過型液晶パネル２４で空間光変調された照明光は、画像光として光路偏向手段２９に入射し、この光路偏向手段２９によって画像光が画素の配列方向に所定の距離だけシフトされる。この光は投影レンズ２５で拡大されスクリーン２６上に投影される。
【０１０３】
光路偏向手段２９により画像フィールドを、時間的に分割した複数のサブフィールド毎の光路の偏向に応じて、表示位置をずらした状態の画像パターンを表示させることで、透過型液晶パネル２４の見掛け上の画素数を増倍して表示する。このように光路偏向手段２９によるシフト量は、透過型液晶パネル２４の画素の配列方向に対して２倍の画像増倍を行うことから、画素ピッチの１／２に設定される。シフト量に応じて、透過型液晶パネル２４を駆動する画像信号をシフト量分だけ補正することで、見掛け上高精細な画像を表示することができる。
【０１０４】
この際、光路偏向手段２９として、前述した各実施の形態のような光偏向素子を用いているので、光の利用効率を向上させ、光源の負荷を増加することなく、観察者に明るく高品質の画像を提供できる。光路偏向制御を、当該光路偏向素子１における電極対４、４による電界印加方向及び電界強度により行うことで、適切なピクセルシフト量が保持され良好な画像を得ることができる。
【０１０５】
（実施例１）
図８は光路偏向素子の動作を確認するための試験装置を示す図である。
同図において符号１’は空セル、３１は電界印加用の電源をそれぞれ示す。
厚さ１ｍｍのガラス基板の表面に厚み６００Åのホメオトロピック配向膜を形成した。厚み８０μｍ、幅１．０ｍｍ、長さ１２ｍｍのアルミ電極シートをスペーサー兼電極とし、有効領域が１ｃｍ幅となるように電極対を平行に配置した図８のような空セル１’を作製した。
次に市販の光重合開始剤を１重量部と、（７）式、および（８）式で示した化合物を各々５０重量部ずつからなる液晶性アクリレート組成物１重量％と強誘電性液晶「ＣＳ１０２９」（チッソ製）９９重量％からなる強誘電性液晶組成物を調整した。
【０１０６】
空セル１’と強誘電性液晶組成物を約８０℃に加熱した状態で、空セル１’に強誘電性液晶組成物を注入した。このセルを、液晶がスメクチックＡ相を示す温度まで冷却し、スメクチックＡ相の垂直配向状態を維持したまま６０ｍＪ／ｃｍ^２の紫外線を照射した。その後、室温まで冷却して接着剤で封止し、光路偏光素子１としての高分子安定化垂直配向強誘電性液晶セルを得た。電極対４、４にパルスジェネレータと高速アンプとからなる電源３１を接続し、試験装置を構成した。
【０１０７】
無電界の状態で、この光路偏向素子の有効領域内における液晶層のコノスコープ像を室温下で観察したところ、十字形と円環の画像が中心部に観察された。したがって、無電界下では光学軸が液晶層に垂直であることを確認できた。この状態では液晶分子のチルト方向が、基板面に垂直な方向に対して回転する螺旋構造を取っており、平均的な光学軸は螺旋軸の方向である基板面に垂直な方向として観察される。
【０１０８】
次に、電源３１から電極対４、４に±３ｋＶ、１Ｈｚの矩形波電圧を印加したところ、コノスコープ像の十字と円環の位置が上下方向に１Ｈｚで往復シフトした。顕微鏡の対物レンズのＮＡ値と、液晶の屈折率と、十字位置のシフト量から光学軸の傾斜角度を計算すると約２０度であった。
【０１０９】
空間周波数が１００ｌｐ／ｍｍの矩形波に相当する開口部が５μｍ角のマスクパターンを裏面から照明し、その透過光を図８に示す装置に組み込んだ光路偏向素子１を通して観察した。光路偏向素子１を動作させることでマスクパターンの位置がシフトしたように観察される。このシフトの様子を顕微鏡付き高速度カメラで観察することで、光路シフト量とその応答時間を測定した。電源３１から電極対４、４に±３ｋＶ、１２０Ｈｚの矩形波電圧を印加しながら、高速度カメラによる観察（時間分解能４０５００フレーム／秒）を行ったところ、シフト量は７μｍ、その移動に要する応答時間は１ｍｓｅｃであり、実用上問題無いシフト量と高速応答性を示した。
【０１１０】
この動作を８時間連続で行っても液晶層の配向状態に変化は見られなかった。また、駆動のオン／オフを繰り返しても液晶層の配向状態に変化は見られなかった。したがって、光路偏向動作にも劣化などが無く、安定した光路偏向素子が得られた。
【０１１１】
（比較例１）
電極兼スペーサーのアルミシート厚みを６５μｍに減らして、液晶性ジアクリレート組成物による高分子安定化液晶セルにしなかった以外は、実施例１と同様にした。液晶材料として「ＣＳ１０２９」（チッソ製）を用いた場合、コノスコープ測定による光学軸の傾斜角度は２５度であった。高速度カメラによる測定では、シフト量は９μｍ、その移動に要する応答時間は０．８ｍｓｅｃであり、実用上問題無いシフト量と高速応答性を示した。
この動作を８時間連続で行ったところ、有効領域の液晶層中に僅かな白濁部が発生した。この状態で、駆動のオン／オフを繰り返したところ、白濁部が成長した。この状態では液晶素子の光透過率が減少し、光散乱が発生した。
この素子を８０℃まで加熱して再冷却することで、初期の配向性の良い状態に戻すことができたが、安定した光路偏向素子は得られなかった。
【０１１２】
（実施例２）
強誘電性液晶組成物と、光重合時の操作と条件を、以下のように変えた以外は実施例１と同様にして液晶セルを作成した。液晶層の厚みは６５μｍに設定した。
市販の光重合開始剤を１重量部と、（３）式に示した化合物の液晶性ジアクリレート組成物０．５重量％と、強誘電性液晶「ＣＳ２００５」（チッソ製）９９．５重量％からなる強誘電性液晶組成物を調整した。
ＣＳ２００５はスメクチックＡ相を示さず、スメクチックＣ相の配向性が悪いが、自発分極とチルト角が比較的大きい。
【０１１３】
空セルと強誘電性液晶組成物を約８０℃に加熱した状態で、空セルに強誘電性液晶組成物を注入した。このセルの電極対に±２０００Ｖ、２００Ｈｚの交流電圧を印加した状態で冷却したところ、キラルネマチック相からキラルスメクチックＣ相への転移温度近傍で配向乱れによる白濁が一時的に発生したが、徐々に配向性が回復した。その後、室温まで冷却しても比較的配向性の良いキラルスメクチックＣ相の垂直配向状態を維持した。その状態で６０ｍＪ／ｃｍ^２の紫外線を照射した。その後、接着剤で封止し、高分子安定化垂直配向強誘電性液晶セル、すなわち光路偏光素子１を得た。この光路偏向素子を図８に示す試験装置に組み込んだ。
【０１１４】
無電界の状態で、この光路偏向素子の有効領域内において液晶層のコノスコープ像を室温下で観察したところ、十字形と円環の画像が中心部に観察された。したがって、無電界下では光学軸が液晶層に垂直であることを確認できた。次に、電源から電極対に±３ｋＶ、１Ｈｚの矩形波電圧を印加したところ、コノスコープ像の十字と円環の位置が上下方向に１Ｈｚで往復シフトした。顕微鏡の対物レンズのＮＡ値と、液晶の屈折率と、十字位置のシフト量から光学軸の傾斜角度を計算すると約２５度であった。
【０１１５】
実施例１と同様、開口部が５μｍ角のマスクパターンを裏面から照明し、その透過光を図８に示した試験装置に組み込んだ本実施例の光路偏向素子を通して観察した。光路偏向素子を動作させることでマスクパターンの位置がシフトしたように観察される。このシフトの様子を顕微鏡付き高速度カメラで観察することで、光路シフト量とその応答時間を測定した。電源から電極対に±３ｋＶ、１２０Ｈｚの矩形波電圧を印加しながら、高速度カメラによる観察（時間分解能４０５００フレーム／秒）を行ったところ、シフト量は７μｍ、その移動に要する応答時間は１ｍｓｅｃであり、実用上問題無いシフト量と高速応答性を示した。
【０１１６】
（３）式に示す化合物のような、液晶性ジアクリレート化合物を重合した場合、３次元網目組織を形成するため液晶層の配向安定化の効果は非常に大きいと考えられるが、同時に液晶分子の切換え動作を制限する効果も大きいため、応答速度が遅くなることが懸念される。そこで、本実施例のように、自発分極とチルト角が大きく、高速応答性に優れるが、配向安定性が比較的悪い液晶材料と組合せることで、実用的な応答速度を確保しつつ、配向安定性も向上させることが出来た。
【０１１７】
この動作を８時間連続で行っても、液晶層の配向状態に変化は見られなかった。また、駆動のオン／オフを繰り返しても、液晶層の配向状態に変化は見られなかった。したがって、光路偏向動作にも劣化などが無く、安定した光路偏向素子が得られた。
【０１１８】
（比較例２）
液晶注入後に交流電界を印加しなかった以外は、実施例２と同様にした。実施例２の液晶は配向性が悪いために、冷却時に、キラルネマチック相からキラルスメクチックＣ相への転移温度近傍で配向乱れによる白濁が発生し始め、室温でもそのまま白濁が残ってしまった。この状態で光重合を行っても、配向が乱れたまま状態が固定化されてしまうため、重合による高分子組織の形成を行わなかった。
【０１１９】
（実施例３）
実施例１同様な空セルを作成した。液晶層の厚みは６５μｍに設定した。
次に市販の光重合開始剤を１重量部と（５）式に示した化合物の液晶性アクリレート組成物１重量％と、強誘電性液晶「ＣＳ１０２４」（チッソ製）９９重量％からなる強誘電性液晶組成物を調整した。ＣＳ１０２４は単体でも配向性は比較的良く、応答速度も十分であるが、長時間動作時の安定性は更なる改善の余地が有る。
【０１２０】
空セルと強誘電性液晶組成物を約８０℃に加熱した状態で、空セルに強誘電性液晶組成物を注入した。このセルを液晶がスメクチックＡ相を示す温度まで冷却し、スメクチックＡ相の垂直配向状態を維持したまま６０ｍＪ／ｃｍ^２の紫外線を照射した。その後、室温まで冷却して接着剤で封止し、高分子安定化垂直配向強誘電性液晶セルを得た。この光路偏向素子を図８に示す試験装置に組み込んだ。
【０１２１】
無電界の状態で、この光路偏向素子の有効領域内において液晶層のコノスコープ像を室温下で観察したところ、十字形と円環の画像が中心部に観察された。したがって、無電界下では光学軸が液晶層に垂直であることを確認できた。次に、電源から電極対に±３ｋＶ、１Ｈｚの矩形波電圧を印加したところ、コノスコープ像の十字と円環の位置が上下方向に１Ｈｚで往復シフトした。顕微鏡の対物レンズのＮＡ値と、液晶の屈折率と、十字位置のシフト量から光学軸の傾斜角度を計算すると約２５度であった。
【０１２２】
実施例１と同様、開口部が５μｍ角のマスクパターンを裏面から照明し、その透過光を図８に示す試験装置に組み込んだ光路偏向素子を通して観察した。光路偏向素子を動作させることでマスクパターンの位置がシフトしたように観察される。このシフトの様子を顕微鏡付き高速度カメラで観察することで、光路シフト量とその応答時間を測定した。電源から電極対に±３ｋＶ、１２０Ｈｚの矩形波電圧を印加しながら、高速度カメラによる観察（時間分解能４０５００フレーム／秒）を行ったところ、シフト量は７μｍ、その移動に要する応答時間は１．５ｍｓｅｃであり、実用上問題無いシフト量と高速応答性を示した。
【０１２３】
（５）式に示す化合物のような、メチレンスペーサーを有する液晶性アクリレート化合物を重合した場合、側鎖型の液晶ポリマーを形成するため、液晶層の配向安定化の効果は比較的小さいと考えられるが、液晶分子の切換え動作を制限する効果は小さいため、応答速度への影響は少ない。そこで、本実施例のように配向安定性が比較的良い液晶材料と組合せることで、実用的な応答速度を確保しつつ、長期的な配向安定性を維持することが出来る。
【０１２４】
この動作を８時間連続で行っても、液晶層の配向状態に変化は見られなかった。また、駆動のオン／オフを繰り返しても、液晶層の配向状態に変化は見られなかった。したがって、光路偏向動作にも劣化などが無く、安定した光路偏向素子が得られた。
【０１２５】
（比較例３）
液晶性アクリレート組成物による高分子安定化液晶セルにしなかった以外は、実施例３と同様にした。高速度カメラによる測定では、シフト量は９μｍ、その移動に要する応答時間は１．３ｍｓｅｃであり、実用上問題無いシフト量と高速応答性を示した。
この動作を８時間連続で行ったところ、有効領域の液晶層中に僅かな白濁部が発生した。この状態で、駆動のオン／オフを繰り返したところ、白濁部が成長した。この状態では素子の光透過率が減少し、光散乱が発生した。
この素子を８０℃まで加熱して再冷却することで、初期の配向性の良い状態に戻すことができたが、安定した光路偏向素子は得られなかった。
【０１２６】
（実施例４）
図９は第２の電極対を有する光路偏光素子を用いた光路偏向装置を示す図である。
同図において符号３２は第２の電極を示す。
同図に示すように第２の電極対４”、４”を設けた以外は、実施例１と同様な空セル１’を作成した。実施例１と同様な強誘電液晶性組成物を注入し、実施例２と同様に交流電圧を印加した状態で冷却して、室温でも配向性の良いキラルスメクチックＣ相を形成した。次に図９に示す光路偏向装置を組み、第２の電極対４”、４”に第２の電源３２から２００Ｖ／ｍｍの直流電界を印加した状態で同様に光重合を行った。その後、接着剤で封止し、高分子安定化垂直配向強誘電性液晶セルを得た。第２の電極対４”、４”による電界の方向は、光路偏向駆動用の電界と異なる方向であり、図２のようにキラルスメクチックＣ相の螺旋が解けて液晶分子が駆動時以外の方向に傾斜した状態で高分子安定化されていると考えられる。
【０１２７】
図１０は光路偏向素子の透過光の検出装置を示す模式図である。
同図において、符号３３、３４は偏光板、３５は光検出器をそれぞれ示す。
同図の光路偏光素子１は、図９に示した光路偏向装置に組み込まれた状態で用いられているものとする。ただし、実使用時は電極対４”、４”には電界をかけないので、第２の電源３２は外しておく。
実施例４で作成した光偏向素子１を用いた図９に示す光路偏向装置を、図１０に示すような装置に組み込んで過渡光散乱の時間の強度を測定した。以下の説明においては、図９に示した符号も援用する。
図１０（ａ）は、光路偏光素子１に図９に示した電源３１によって所定の電界がかけられ、液晶分子が均一に配列している状態を示す図である。図１０（ｂ）は電界の反転時に過渡的に液晶分子の配列が乱れたときの状態を示す図である。
【０１２８】
無偏光のレーザー光Ｌ０を偏光板３３を通して図の上下方向の偏光Ｌ１として光偏向素子１に入射させる。入射光Ｌ１の偏光方向と光偏向素子１の偏向方向が一致するように配置し、光偏向素子１の後にクロスニコルの偏光板３４を配置する。図１０（ａ）に示すように、光路偏向素子１に所定の電界がかけられた状態では、光路偏向素子１内の液晶分子が均一に配向し、光路シフト現象は生じるが、偏光面の回転や乱れは生じないため、透過光Ｌ１’は後の偏光板３４を透過しない。一方、図１０（ｂ）に示すように、光路偏向素子１にかけられる電界が反転するときの過渡的状態では、液晶分子の配向が乱れているため偏光面も乱れて、透過光Ｌ２は散乱光となり、後の偏光板３４を漏れて出てくる紙面に垂直な偏光方向を有する光Ｌ３が生じる。この漏れて出てきた光Ｌ３の強度と時間を光検出器３５で検出することで、過渡光散乱の強度や時間を測定することが出来る。
【０１２９】
図１０に示す光路偏向素子１において、第１電源３１から第１電極対４、４に±２０００Ｖ、１００Ｈｚの矩形波電圧を印加し、測定を行ったところ、過渡的な光散乱による漏れ光Ｌ３の検出電圧は１０ｍＶ、漏れ光の検出時間は１ｍｓｅｃであった。この駆動条件での光路シフトの様子を実施例１と同様に、開口部が５μｍ角のマスクパターンを裏面から照明し、その透過光を図９に示した光路偏向素子を通して顕微鏡付き高速度カメラで観察した。
【０１３０】
図１１は透過光のパターンの移動の様子を示す図である。
同図において、符号３６はマスクパターンの透過光のパターンの位置を示す。開口部が移動する時に、透過光のパターンの位置３６は図１１に示すように僅かに円弧状の軌跡を描いて第１の位置３６ａから、中間点３６ｂを経由して第２の位置３６ｃへ移動した。また、移動中も開口ドットは比較的コントラスト良く観察された。したがって、液晶分子の反転時の回転方向が一方向に制御され、反転に伴う過渡光散乱が問題無いレベルであり、この程度の漏れ光強度と時間では実際の光路シフト現象では実用上問題無いと判断した。
【０１３１】
（比較例４）
実施例４に対して、第２の電極対に直流電界を印加しないで光重合を行った液晶素子を用いて、同様な過渡光散乱の測定を行った。漏れ光の検出電圧は２０ｍＶ、漏れ光の検出時間は１．５ｍｓｅｃであった。また、開口部の移動過程を高速度カメラで観察したところ、直線状の軌跡を描いた。また、移動中に開口ドットがボケて過渡的な光散乱が起きていることが観察された。液晶分子の反転時の回転方向を制御していないため、反転に伴う過渡光散乱が起きているが、漏れ光の発生時間は比較的短く、実用上許容範囲であると判断した。
【０１３２】
（実施例５）
図５に類似の４方向シフト装置を作成し、図７に類似の画像表示装置を構成した。以下に示す符号は両図に示した符号に準ずる。画像表示素子２４として対角０．９インチＸＧＡ（１０２４×７６８ドット）のポリシリコンＴＦＴ液晶ライトバルブを用いた。画素ピッチは縦横ともに約１８μｍである。画素の開口率は約５０％である。また、画像表示素子２４の光源側にマイクロレンズアレイを設けて照明光の集光率を高める構成とした。本実施例では、光源２１としてＲＧＢ三色のＬＥＤ光源を用い、上記の一枚の液晶パネルの画像表示素子２４に照射する光の色を高速に切換えてカラー表示を行う、いわゆるフィールドシーケンシャル方式を採用している。
【０１３３】
本実施例では、画像表示のフレーム周波数が６０Ｈｚ、ピクセルシフトによる４倍の画素増倍のため、サブフィールド周波数は４倍の２４０Ｈｚとする。一つのサブフレーム内をさらに３色分に分割するため、各色に対応した画像を７２０Ｈｚで切換える。液晶パネルの画像表示素子２４の各色の画像の表示タイミングに合わせて、対応した色のＬＥＤ光源２１をオン／オフすることで、観察者にはフルカラー画像が見える。
光路偏向素子１の基本構成は実施例１と同様である。また、外気の送風ファンを設け、光路偏向素子１の温度が外気温と同じ２５℃となるように空冷した。
【０１３４】
光路偏向素子を２組用い、入射側を第１光路偏向素子１０、出射側を第２光路偏向素子１２とした。互いの透明電極ライン４の方向が直交し、画像表示素子２４の画素の配列方向に一致するように配置した。本実施例では画像表示素子２４の液晶ライトバルブからの出射光が既に直線偏光であり、その偏光方向が第一光路偏向素子１０の光路偏向方向と一致するように配置されているが、光路偏向素子への入射光の偏光度を確実にするために、光路偏向素子１０の入射面側に偏光方向規制手段として直線偏光板を設けた。
【０１３５】
さらに、第１、第２光路偏向素子の間に偏光面回転素子１１’を設けた。偏光面回転素子１１’は、２枚のガラス基板（３ｃｍ×４ｃｍ、厚さ３ｍｍ）上にポリイミド系の配向材料をスピンコートし、約０．１μｍの配向膜を形成した。ガラス基板のアニール処理後、ラビング処理を行った。２枚のガラス基板の周辺部に８μｍ厚のスペーサを挟んでラビング処理面を対向させ、ラビング方向が直交するように両基板を張り合わせて空セルを作製した。このセルの中に、誘電率異方性が正のネマチック液晶にカイラル材を適量混合した材料を常圧下で注入し、液晶分子の配向が９０度捻じれたＴＮ液晶セルを作成した。
【０１３６】
このセルには電極を設けていないため、単なる偏光回転素子１１’として機能する。また、両光路偏向素子１０、１２のアルミ電極間での放電を防止する。第１光路偏向素子１０から出射した光の偏光面と偏光回転素子１１’の入射面のラビング方向が一致するように、２つの光路偏向手段の間に挟んで配置した。偏光面回転素子１１’により第１光路偏向素子１０からの出射光の偏光面が９０度回転し、第２光路偏向素子１２の偏向方向に一致する。第１光路偏向素子１０、偏光面回転素子１１’、第２光路偏向素子１２からなる光偏向装置２９を画像表示素子２４の直後に設置した。
【０１３７】
光路偏向素子１０、１２を送風ファンで約２５℃に冷却し、光路偏向素子１０、１２を駆動する矩形波電圧の電圧を±３ｋＶ（平均電界は±３００Ｖ／ｍｍ）、周波数を１２０Ｈｚとし、２枚の光路偏向素子にかける矩形波の位相を図６で示したように９０度ずらして、４方向に画素シフトするように駆動タイミングを設定した。この駆動電圧では光路シフト量は約９μｍで、１／２画素分だけ画素がシフトして表示される。
【０１３８】
画像表示素子２４に表示するサブフィールド画像を２４０Ｈｚで書き換えることで、縦横２方向に見かけ上の画素数が各２倍に増倍したフレーム周波数６０Ｈｚの画像が表示できた。画像中央から端部まで画素シフト量は均一であり、高精細な画像が得られた。光路偏向素子１０、１２の切換え時間は約１ｍｓｅｃであり、充分な光利用効率が得られた。また、フリッカーなどは観測されなかった。さらに８時間の連続運転後も高精細な画像を維持していた。
【０１３９】
（比較例５）
光路偏向素子１として液晶層厚１０μｍのツイストネマチック液晶セルによる旋光素子と、ＬｉＮｂＯ_３の複屈折素子を編み合わせた素子を使用した以外は実施例５と同様にした。実施例５と同様に符号は図５、７を援用する。
２組の光路偏向素子１０、１２を用いて、両者の間に実施例５と同様な偏光面回転素子１１’を設けた。光路偏向素子１０、１２を送風ファンで約２５℃に冷却し、光偏向素子１０、１２を駆動する矩形波電圧の電圧を±１０Ｖ、周波数を１２０Ｈｚとし、２枚の光路偏向素子１０、１２にかける矩形波の位相を９０度ずらして、４方向に画素シフトするように駆動タイミングを設定した。
【０１４０】
この駆動電圧では光路シフト量は約９μｍで、１／２画素分だけ画素がシフトして表示されるが、この光路偏向素子１０、１２の応答速度は１５ｍｓｅｃであり、１２０Ｈｚの高速駆動には応答できなかった。そこで、光路偏向素子１０、１２を６０Ｈｚで駆動し、画像表示素子２４に表示するサブフィールド画像を１２０Ｈｚで書き換えることで、縦横２方向に見かけ上の画素数が各２倍に増倍したフレーム周波数３０Ｈｚの画像が表示できた。しかし、フリッカーなどが観測された。また、光路シフト量の波長依存性が大きく、シフト位置外にゴースト画素が発生した。
【０１４１】
【発明の効果】
基板間に充填されたホメオトロピック配向をなすキラルスメクチックＣ相の液晶層が、繊維状、あるいは網目状の組織を含有するため、配向状態が安定化し、繰り返しの使用においても配向が乱れることがなくなる。
【図面の簡単な説明】
【図１】本発明の第１実施形態を説明するための光路偏向素子の断面模式図である。
【図２】光偏向動作時とは異なる方向の直流電界を印加しながら高分子重合させる様子を示す模式図である。
【図３】高分子材料として液晶性ポリマーを用いた場合の液晶層の状態を示す模式図である。
【図４】光路偏向素子への入射光の偏光方向を特定の方向に規制する手段を有する光路偏向装置の概要を示す図である。
【図５】光路偏向素子の組み合わせによる４方向シフト装置の構成を説明するための概略図である
【図６】４方向シフト装置の駆動の一例を示すタイミングチャートである。
【図７】光路偏向素子を用いた画像表示装置の概要図である。
【図８】光路偏向素子の動作を確認するための試験装置を示す図である。
【図９】第２の電極対を有する光路偏光素子を用いた光路偏向装置を示す図である。
【図１０】光路偏向素子の透過光の検出装置を示す模式図である。
【図１１】透過光のパターンの移動の様子を示す図である。
【図１２】光路偏向素子の断面を模式的に示した図である。
【図１３】異なる電極構成の例を示す図である。
【図１４】図１２に示した構成に関して電界方向と液晶分子の傾斜方向を模式的に示した図である。
【図１５】図１４の状態から電界が反転したときの様子を示す模式図である。
【図１６】液晶分子の配向状態と光路偏向の原理を模式的に示した図である。
【図１７】図１６において電界を反転させた状態を模式的に示した図である。
【図１８】スメクチックＣ相における配向欠陥の発生を説明するための図である。
【図１９】図１４、１５と同様に光路偏向素子内の液晶分子の傾斜状態を示した図である。
【符号の説明】
１、１０、１２ 光路偏光素子
２ 基板
３ 垂直配向膜
４ 電極
５ 液晶層
７ スペーサ
８ 直線偏光板
９ ４方向シフト装置
１１ ２分の１波長板[0001]
[Industrial applications]
The present invention relates to an optical path deflecting element that changes the direction of light by an electric signal, an optical deflecting device, and an image display device using the optical path deflecting element or the optical deflecting device. Optical path shift elements are used in electronic display devices such as projection displays and head mounted displays.
[0002]
[Prior art]
Prior to the description of the related art, terms used in this specification are defined.
The "optical path deflecting element" means that the optical path of light is deflected by an external electric signal, that is, the outgoing light is shifted in parallel with respect to the incident light, rotated at a certain angle, or both. Means an optical element capable of switching the optical path. In this description, the magnitude of the shift in the optical path deflection by the parallel shift is referred to as “shift amount”. “Optical path deflecting device” means a device that includes such an optical path deflecting element and deflects the optical path of light.
[0003]
The “pixel shift element” is an image display element in which a plurality of pixels capable of controlling light at least according to image information are two-dimensionally arranged, a light source for illuminating the image display element, and an image displayed on the image display element. An optical member for observing the pattern; and a light deflecting unit for deflecting an optical path between the image display element and the optical member for each of a plurality of subfields obtained by temporally dividing the image field. Means optical path deflecting means in an image display device that displays an image pattern in which the display position is shifted according to the deflection of the optical path for each field, thereby increasing the apparent number of pixels of the image display element and displaying the image. I do. Therefore, basically, it can be said that the optical path deflecting element and the optical path deflecting device as defined above can be applied as the optical path deflecting means.
[0004]
Conventionally, KH has been used as an optical element as an optical path deflecting element. ₂ PO ₄ (KDP), NH ₄ H ₂ PO ₄ (ADP), LiNbO ₃ , LiTaO ₃ , GaAs, CdTe, etc., materials having a large primary electro-optic effect (Pockels effect), KTN, SrTiO ₃ , CS ₂ Device using a material having a large secondary electro-optic effect, such as glass, silica, TeO ₂ An acousto-optic device using such a material is known (for example, see Non-Patent Document 1). These generally require a long optical path length in order to obtain a sufficiently large optical path deflection amount, and their use is limited due to the expensive material.
[0005]
On the other hand, various optical elements as optical path deflecting elements using a liquid crystal material have been proposed, and there are the following proposal examples to name a few.
For the purpose of reducing the loss of light of the optical space switch, a light beam shifter including an artificial birefringent plate has been proposed (for example, see Patent Document 1). In detail, two wedge-shaped transparent substrates are arranged in opposite directions, a light beam shifter having a liquid crystal layer sandwiched between the transparent substrates, and a light in which the light beam shifter is connected to a rear surface of a matrix-type deflection control element. A beam shifter has been proposed. In addition, two wedge-shaped transparent substrates are arranged in opposite directions, and a matrix drive can be performed between the transparent substrates, and a light beam shifter that sandwiches a liquid crystal layer that shifts an incident light beam by half a cell is used. There has been proposed a light beam shifter in which a half cell is shifted and connected in multiple stages.
[0006]
Further, there has been proposed an optical deflection switch which can obtain a large deflection, has a high deflection efficiency, and can arbitrarily set a deflection angle and a deflection distance (for example, see Patent Document 2). Specifically, two transparent substrates are arranged facing each other at a predetermined interval, the surfaces facing each other are subjected to a vertical alignment treatment, and a liquid crystal of a smectic A phase is sealed between the transparent substrates. The liquid crystal device is provided with a driving device for arranging an electrode pair so that an AC electric field can be applied in parallel with the smectic layer and applying an AC electric field to the electrode pair. That is, the refraction angle and the direction of displacement of the polarized light incident on the liquid crystal layer can be changed by the birefringence caused by the tilt of the liquid crystal molecules using the electroclinical effect of the liquid crystal of the smectic A phase.
[0007]
In the former Patent Document 1, since a nematic liquid crystal is used as a liquid crystal material, it is difficult to increase the response speed to sub-millisecond, and it cannot be used for applications requiring high-speed switching.
Further, in the latter Patent Document 2, a smectic A phase liquid crystal is used. However, since the smectic A phase has no spontaneous polarization, high-speed operation cannot be expected.
[0008]
Next, several techniques that have been conventionally proposed for the pixel shift element will be described.
In a projection display device for enlarging and projecting an image displayed on a display element onto a screen by a projection optical system, at least one or more optical elements capable of rotating the polarization direction of transmitted light in the optical path from the display element to the screen are provided. Means for shifting a projected image having at least one transparent element having a birefringence effect, and an aperture ratio of the display element is effectively reduced, and a projection area of each pixel of the display element is provided on the screen. There is a projection display device provided with means for discretely projecting the above (for example, see Patent Document 3).
[0009]
In Patent Document 3, a projection including at least one optical element (referred to as an optical rotation element) capable of rotating the polarization direction and at least one transparent element having a birefringent effect (referred to as a birefringent element) is disclosed. Pixel shift is performed by image shift means (pixel shift means). The problems are that the optical rotation element and the birefringent element are used in combination, so that the light loss is large, the pixel shift amount fluctuates due to the wavelength of the light, and the resolution tends to be reduced, and the optical rotation between the optical rotation element and the birefringent element. Optical noise such as ghost due to leaked light is likely to be generated at a position outside the pixel shift where an image is not originally formed due to the mismatch of characteristics, and the cost for element formation is large. In particular, KH as described above is used for the birefringent element. ₂ PO ₄ (KDP), NH ₄ H ₂ PO ₄ (ADP), LiNbO ₃ , LiTaO ₃ This is remarkable when a material having a large first-order electro-optic effect (Pockels effect) such as GaAs, GaAs, and CdTe is used.
[0010]
In addition, the control circuit samples the images to be displayed originally stored in the image storage circuit in a checkered pattern to the pixel selection circuit, sequentially displays the images on the spatial light modulator, and projects the images. There is a projector that controls a panel swinging mechanism to move an adjacent pixel pitch distance of the spatial light modulator by an integral number, thereby reproducing an image to be originally displayed by temporal synthesis. (See, for example, Patent Document 4). This makes it possible to display an image at a resolution of an integral multiple of the pixels of the spatial light modulator, and to configure a projector at low cost using a spatial light modulator with coarse pixels and a simple optical system.
[0011]
However, Patent Document 4 describes a pixel shift method in which the image display element itself is swung at a high speed by a distance smaller than the pixel pitch. In this method, since the optical system is fixed, various types of aberrations are generated. Although the occurrence is small, it is necessary to translate the image display element itself accurately and at high speed, so that the accuracy and durability of the movable part are required, and vibration and sound become problems.
[0012]
Furthermore, in order to increase the apparent resolution of a display image without increasing the number of pixels of an image display device such as an LCD, each of a plurality of pixels arranged in a vertical direction and a horizontal direction has a display pixel pattern. By emitting light according to, an image display device on which an image is displayed, and an optical member that changes the optical path for each field between the observer or the screen, and for each field, the optical path change There has been proposed a device in which a display pixel pattern in a state where the display position is shifted according to the above is displayed on an image display device (for example, see Patent Document 5). Here, the portion having a different refractive index is alternately displayed in the optical path between the image display device and an observer or a screen for each field of image information, whereby the optical path is changed. It is.
[0013]
Patent Document 5 describes, as means for changing the optical path, a combination mechanism of an electro-optical element and a birefringent material, a lens shift mechanism, a variangle prism, a rotating mirror, a rotating glass, and the like. In addition to the method using a combination of refractive elements, a method has been proposed in which an optical path is switched by displacing (translating, tilting) an optical element such as a lens, a reflector, or a birefringent plate using a voice coil or a piezoelectric element. In this method, the structure is complicated and the cost is high for driving the optical element.
[0014]
In addition, a light beam deflecting device has been proposed that can eliminate the need for a rotating mechanical element, can realize a small overall size, achieve high precision and high resolution, and is hardly affected by external vibration (for example, Patent Document 6). reference.). Specifically, a translucent piezoelectric element disposed on the traveling path of the light beam, a transparent electrode provided on the surface of the piezoelectric element, a light beam incident surface A and a light beam exit surface B of the piezoelectric element. Voltage applying means for applying a voltage to the piezoelectric element via an electrode in order to deflect the optical axis of the light beam by changing the optical path length between them.
[0015]
Patent Document 6 proposes a method in which a light-transmitting piezoelectric element is sandwiched between transparent electrodes and a voltage is applied to change the thickness to shift the optical path, but a relatively large transparent piezoelectric element is required. However, there is a problem similar to that of the above-mentioned Patent Document 5, such as an increase in apparatus cost.
[0016]
[Patent Document 1]
JP-A-6-18940 (page 2, claims 1, 2, paragraph 0004)
[Patent Document 2]
JP-A-9-133904 (page 3, paragraphs 0017 to 0019)
[Patent Document 3]
Japanese Patent No. 2939826 (Claim 1, pages 4 to 5, FIGS. 4 to 5)
[Patent Document 4]
JP-A-5-313116 (Claim 1, pages 1-2, FIG. 1)
[Patent Document 5]
JP-A-6-324320 (page 5, FIG. 5)
[Patent Document 6]
JP-A-10-133135 (pages 3-4, paragraphs 0020-0024)
[Non-patent document 1]
Shoji Aoki "Optoelectronic Device," First Edition, First Printing, Japan, Shokodo, October 31, 1986, p. 119-161
[0017]
[Problems to be solved by the invention]
As described above, in the conventional technology, the optical path deflecting device with the simplified configuration and the small size cannot sufficiently speed up the optical path shifting operation, and the optical deflecting device with the increased optical path shifting operation However, there are problems such as the complexity of the device configuration, the increase in cost and the size of the device accompanying the complexity of the device configuration.
The present inventors aligned liquid crystal molecules composed of a chiral smectic C phase forming a homeotropic alignment between a pair of substrates substantially vertically, and generated an electric field in a direction substantially parallel to the liquid crystal layer to change the direction of the liquid crystal molecules. It has been found that an optical path deflecting element configured to shift a pixel in a desired direction to perform a pixel shift enables a high-speed pixel shift with a relatively simple configuration (Japanese Patent Application No. 2001-014321). High cost, large device, light loss, optical noise, etc. due to the complicated structure of the conventional optical path deflecting element can be improved, and the responsiveness of the conventional smectic A liquid crystal or nematic liquid crystal can be improved. , High-speed response was made possible.
[0018]
In this optical path deflecting element, by applying an AC voltage (for example, a rectangular wave voltage) of about several hundred Hz between a pair of electrodes, the optical path of the incident light is switched in two directions at a switching timing of several hundred Hz and emitted. be able to. As described above, since the optical path shift utilizes the afterimage phenomenon of the human eye, the switching timing of the optical path of the incident light may be 30 Hz or more, but in order to surely prevent flicker, one hundred to several hundred Preferably, it is set to 100 Hz.
[0019]
By the way, in order to obtain a practical optical path shift amount of about several μm to several tens of μm with such an optical path deflection element, it is necessary to set the thickness of the liquid crystal layer to be relatively thick, from several tens μm to several hundred μm. However, there are only a few examples of ferroelectric liquid crystals which form a sufficiently thick vertical alignment smectic phase as liquid crystal elements. As a result of the study by the inventors, it has been found that cloudiness may occur in the liquid crystal portion when the optical path deflecting element is produced or due to continuous optical path shift driving.
[0020]
In general, when liquid crystal molecules are uniformly vertically aligned in a liquid crystal layer, a dark crosshair conoscopic image called an isojare can be clearly observed in the liquid crystal layer, but in a portion where white turbidity occurs, The conoscopic image was very unclear, and no isojares were observed in the highly cloudy areas. This is evidence that the vertical alignment state of the liquid crystal molecules is disordered, the directors of the liquid crystal molecules in the turbid portion are not uniform, and a good optical path shift function cannot be obtained with the light deflecting element in which the turbidity occurs. Details will be described later because it becomes complicated.
[0021]
Therefore, in a vertically aligned ferroelectric liquid crystal element having a relatively thick liquid crystal layer, it has been noticed that forming and maintaining a uniform alignment state is an important issue, and the present invention has been achieved.
An object of the present invention is to increase the speed of an optical path shift operation by an optical deflecting element having a simplified configuration, to suppress the occurrence of alignment defects due to repeated use, and to improve the reliability.
[0022]
[Means for Solving the Problems]
According to the first aspect of the present invention, a pair of transparent substrates, a liquid crystal layer capable of forming a chiral smectic C phase having homeotropic alignment filled between the substrates, and a liquid crystal layer parallel to the substrate surface in the liquid crystal layer. And an electrode pair that forms a driving electric field in a desired direction, and switches the direction of the liquid crystal molecules by switching the direction of the driving electric field applied to the electrode pair, thereby switching the tilt direction of the optical axis with respect to the layer normal of the liquid crystal layer. In the optical path deflecting element for switching an optical path from the substrate surface with respect to light incident on the substrate surface, the liquid crystal layer has a fibrous or mesh-like structure.
[0023]
According to a second aspect of the present invention, in the optical path polarizing element according to the first aspect, the thickness of the liquid crystal layer is 10 μm or more.
According to a third aspect of the present invention, in the optical path polarizing element according to the first or second aspect, the optical axis in the absence of an electric field is inclined in a direction of a driving electric field with respect to a layer normal of the liquid crystal layer. It is characterized by.
In the invention according to claim 4, in the optical path polarizing element according to any one of claims 1 to 3, the tissue is formed by polymerizing at least one of a monomer and a prepolymer with a photopolymerization initiator. It is characterized by having.
According to a fifth aspect of the present invention, in the optical path polarizing element according to the fourth aspect, the liquid crystal layer containing the tissue has a light transmittance of 80% or more during the photopolymerization.
[0024]
According to a sixth aspect of the present invention, in the optical path polarizing element according to the fourth or fifth aspect, the structure is polymerized in a temperature range showing a smectic A phase forming a homeotropic alignment.
According to a seventh aspect of the present invention, in the optical path polarizing element according to the fourth or fifth aspect, the tissue has a smectic A phase in a state where an AC electric field is applied in a direction parallel to the substrate surface in the liquid crystal layer. From the above temperature to the temperature of the chiral smectic C phase, and polymerized while the AC electric field is applied.
[0025]
According to an eighth aspect of the present invention, in the optical path polarizing element according to the fourth or fifth aspect, a DC electric field is applied to the tissue in a temperature range showing a chiral smectic C phase in a direction different from that in the light deflection operation. It is characterized by being polymerized in a state.
According to a ninth aspect of the present invention, in the optical path polarizing element according to any one of the first to eighth aspects, the structure has a liquid crystal skeleton as a partial structure.
[0026]
In a tenth aspect of the present invention, in the optical path polarizing element according to the ninth aspect, the structure is obtained by polymerizing a liquid crystalline di (meth) acrylate having a methylene spacer between a liquid crystal skeleton and two acryloyloxy groups. It is characterized by being formed.
According to an eleventh aspect of the present invention, in the optical path polarizing element according to the ninth aspect, the structure is formed by polymerizing a liquid crystal (meth) acrylate having a methylene spacer between a liquid crystal skeleton and one acryloyloxy group. It is characterized by having been done.
[0027]
In the twelfth aspect of the present invention, in the optical path polarizing element according to the ninth aspect, the structure is formed by polymerizing a liquid crystal (meth) acrylate having no methylene spacer between a liquid crystal skeleton and one acryloyloxy group. It is characterized by having been done.
[0028]
According to a thirteenth aspect of the present invention, in the optical path polarizing element according to any one of the first to twelfth aspects, the polarization direction of light incident on the optical path deflecting element is obtained by projecting the optical axis onto a substrate surface. A polarization direction regulating means for setting the direction parallel to the direction.
[0029]
According to a fourteenth aspect of the present invention, in the optical path deflecting element according to the thirteenth aspect, a polarization plane rotating means for rotating a polarization plane of the outgoing light of the optical path deflector in a predetermined direction, and the outgoing light after the polarization plane is rotated And a second optical path polarizing element which makes the incident light the light path polarizing means and the liquid crystal layer normal direction of the second optical path deflecting means substantially coincide with each other, and the electric field directions of the two optical path deflecting means are set to a predetermined angle. It is characterized by being arranged so that it becomes.
[0030]
According to a fifteenth aspect of the present invention, there is provided an image display element having the optical path deflecting element according to any one of the first to fourteenth aspects, wherein a plurality of pixels capable of controlling light in accordance with image information are two-dimensionally arranged. A light source and an illuminating device for illuminating the image display element, an optical device for observing an image pattern displayed on the image display element, and display driving means for forming an image field by a plurality of time-divided subfields. The image display device displays an image pattern in which the display position is shifted according to the deflection state of the optical path for each subfield, thereby increasing the apparent number of pixels of the image display element and displaying the image. I do.
[0031]
In the invention according to claim 16, a pair of transparent substrates are arranged in parallel at a predetermined interval, an electrode pair that forms a driving electric field in a direction parallel to the substrate surface is arranged, and homeotropic alignment is performed between the substrates. A method of manufacturing an optical path deflecting element for forming a liquid crystal layer capable of forming a chiral smectic C phase, wherein the liquid crystal contains a monomer or a prepolymer, and the liquid crystal is injected between the substrates to form a holotropic alignment state. The method is characterized by a method of manufacturing an optical path deflecting element in which at least one of a monomer and a prepolymer is polymerized by a photopolymerization initiator in a state where the optical path deflecting element is used.
According to a seventeenth aspect of the present invention, in the method of manufacturing the optical path deflecting element according to the sixteenth aspect, the transmittance of the liquid crystal layer when performing the polymerization by the light is 80% or more.
[0032]
According to an eighteenth aspect of the present invention, in the method for manufacturing an optical path deflecting element according to the sixteenth or seventeenth aspect, the liquid crystal layer is polymerized in a temperature range showing a smectic A phase forming homeotropic alignment.
According to a nineteenth aspect of the present invention, in the method of manufacturing an optical path deflecting element according to the sixteenth or seventeenth aspect, the smectic A phase is reduced while an AC electric field is applied in a direction parallel to the substrate surface in the liquid crystal layer. The polymer is cooled from a temperature to a temperature of a chiral smectic C phase, and polymerized in a state where the AC electric field is applied.
According to a twentieth aspect of the present invention, in the method for manufacturing an optical path deflecting element according to the sixteenth or seventeenth aspect, a DC electric field in a direction different from that during the light deflection operation is applied in a temperature range showing a chiral smectic C phase. It is characterized by polymerizing with.
[0033]
Embodiment
Prior to the description of the present invention, a configuration and a basic operation of an optical path deflecting element used in the present invention will be described.
FIG. 12 is a diagram schematically showing a cross section of the optical path deflecting element.
In the figure, reference numeral 1 denotes an optical path deflecting element, 2 denotes a substrate, 3 denotes a vertical alignment film, 4 denotes an electrode, and 5 denotes a liquid crystal layer composed of a smectic C phase.
A pair of transparent substrates 2 and 2 are opposed to each other. As the transparent substrate, glass, quartz, plastic, or the like can be used, but a transparent material having no birefringence is preferable. A substrate having a thickness of several tens μm to several mm is used.
[0034]
A vertical alignment film 3 is formed on the inner surface of the substrate 2. The vertical alignment film 3 is not particularly limited as long as it is a material that vertically aligns liquid crystal molecules with respect to the substrate surface, that is, a material that causes homeotropic alignment, but a vertical alignment agent for a liquid crystal display, a silane coupling agent, SiO 2 ₂ An evaporation film or the like can be used.
[0035]
The homeotropic alignment referred to in the present invention is not only a state in which the major axis direction of liquid crystal molecules is aligned perpendicular to the substrate surface with respect to the substrate surface, but also an alignment tilted to about several tens degrees from the normal direction of the substrate surface. Including state. Further, a helical structure may be formed by changing the direction in which the long axis of the liquid crystal molecules is inclined (hereinafter referred to as azimuth angle) in the thickness direction of the liquid crystal layer like a chiral smectic C phase.
[0036]
The distance between the two substrates is defined by sandwiching a spacer, and the electrodes 4 and the liquid crystal layer 5 are formed between the substrates. As the spacer, a sheet member having a thickness of about several μm to several mm or particles of a similar particle size is used, and is preferably provided outside the effective area of the optical path deflecting element. As the electrode 4, a metal such as aluminum, copper, and chromium, and a transparent electrode such as ITO are used. In order to apply a uniform horizontal electric field in the liquid crystal layer, a metal having a thickness approximately equal to the thickness of the liquid crystal layer is used. It is preferable to use a sheet, which is provided outside the effective area of the element.
[0037]
In FIG. 12, as a more preferable example, the spacer member and the metal sheet member are common, and the thickness of the liquid crystal layer is defined by the thickness of the metal sheet member. As the liquid crystal layer, a liquid crystal capable of forming a chiral smectic C phase having homeotropic alignment at room temperature is used. The normal temperature mentioned here is a temperature at which the optical path polarizing element is placed under normal use conditions or storage conditions, and means a temperature range of about 50 ° C. to minus 10 ° C. By applying a voltage between the electrodes, an electric field is applied in the horizontal direction of the liquid crystal layer.
FIG. 13 is a diagram showing an example of an electrode configuration different from that of FIG.
In the figure, reference numeral 4 denotes a transparent line electrode, 6 denotes a dielectric layer, and 7 denotes a spacer.
As shown in FIG. 13, a large number of transparent line electrodes 4 and dielectric layers 6 may be provided in the effective area, and a voltage value that changes stepwise may be applied to each line electrode 4. With this configuration, a uniform horizontal electric field can be applied to a relatively large area.
[0038]
Next, a liquid crystal layer capable of forming a smectic C phase will be described in detail. “Smectic liquid crystal” is a liquid crystal layer in which the major axis direction of liquid crystal molecules is arranged in a layered form (smectic layer). With respect to such a liquid crystal, a liquid crystal in which the normal direction of the layer (the layer normal direction) coincides with the major axis direction of the liquid crystal molecules is referred to as “smectic A phase”, and a liquid crystal in which the normal direction is not coincident is referred to as “ It is called "Smectic C phase". A ferroelectric liquid crystal composed of a smectic C phase generally has a so-called helical structure in which the liquid crystal director direction is helically rotated for each smectic layer in the absence of an external electric field, and is called a "chiral smectic C phase". .
[0039]
In addition, the chiral smectic C reciprocal ferroelectric liquid crystal faces in the direction in which the liquid crystal director faces each layer. Since the liquid crystal composed of these chiral smectic C phases has an asymmetric carbon in the molecular structure and is spontaneously polarized, the liquid crystal molecules are rearranged in a direction determined by the spontaneous polarization Ps and the external electric field E. Optical properties are controlled. In the present embodiment and the like, the optical path deflecting element 1 will be described by taking a ferroelectric liquid crystal as an example of the liquid crystal layer 5, but the same can be used for an antiferroelectric liquid crystal.
[0040]
The chiral smectic C phase has an extremely high-speed response compared to the smectic A phase and the nematic liquid crystal, and is characterized in that switching in sub-ms is possible. In particular, since the direction of the liquid crystal director is uniquely determined with respect to the direction of the electric field, the direction of the director is easier to control and easier to handle than a liquid crystal having a smectic A phase.
[0041]
The liquid crystal layer 5 composed of the smectic C phase having homeotopic alignment has a more restrictive action from the substrate than the liquid crystal layer 5 having a homogeneous alignment (a state in which the liquid crystal director is oriented parallel to the substrate surface). This has the advantage that the optical path deflection direction is easily controlled by adjusting the direction of the external electric field, and the required electric field is low.
[0042]
Further, when the liquid crystal director is homogeneously aligned, the liquid crystal director strongly depends not only on the direction of the electric field but also on the substrate surface, so that a higher positional accuracy is required for the installation of the optical path deflecting element. Conversely, in the case of homeotopic alignment as in the present embodiment, the setting margin of the optical path deflecting element 1 with respect to the light deflection increases. In order to take advantage of these features, the helical axis does not need to be strictly oriented perpendicular to the substrate surface, but may be inclined to some extent. It is only necessary that the liquid crystal director can be oriented in two directions without receiving the restricting force from the substrate.
[0043]
In the present invention, the alignment stability is improved by adding a fibrous or mesh-like structure to the liquid crystal layer, and the transparent substrate, the vertical alignment film, the spacer, the electrodes, and the like are the same as those in the above-described conventional configuration. Can be used.
[0044]
FIG. 14 is a diagram schematically showing the electric field direction and the tilt direction of the liquid crystal molecules in the configuration shown in FIG.
FIG. 15 is a schematic diagram showing a state when the electric field is reversed from the state of FIG. In both figures, reference numeral 5a denotes a liquid crystal molecule, C denotes a virtual cone, d denotes the thickness of a liquid crystal layer, E denotes an electric field direction, Ps denotes spontaneous polarization, and Vs denotes a rectangular wave AC power source.
The side where the width of the liquid crystal molecules 5a is drawn is inclined upward on the paper, and the side where the liquid crystal molecules 5a are drawn is inclined downward on the paper. Further, the spontaneous polarization Ps of the liquid crystal is indicated by an arrow.
[0045]
When the direction of the electric field E is reversed, the azimuth of the liquid crystal molecules 5a that are substantially vertically aligned is reversed from the state shown in FIG. 14 to the state shown in FIG. Here, the relationship between the direction in which the electric field E is applied and the azimuthal angle of the liquid crystal molecules 5a is illustrated when the spontaneous polarization is positive. Here, when the azimuth is reversed, it is considered that the azimuth is rotated in the plane of the virtual cone C as shown in the perspective views of FIGS. 14b and 15b.
[0046]
FIG. 16 is a diagram schematically showing the alignment state of liquid crystal molecules and the principle of optical path deflection.
FIG. 17 is a diagram schematically showing a state where the electric field is inverted in FIG.
In both figures, reference numeral L0 denotes linearly polarized light incident on the optical path deflecting element, L1 denotes outgoing light when the electric field is in one direction, L2 denotes outgoing light when the electric field is inverted, and θ denotes the tilt angle.
The vertical alignment film, spacer, and electrode are omitted. FIGS. 16 and 17 are cross-sectional views of FIGS. 14 and 15 as viewed from the left, respectively. The electric field acts in the front and back directions on the paper. The direction of the electric field is switched by the power supply shown in FIGS. Light incident on the optical path deflecting element 1 is linearly polarized light. Here, the tilt angle θ is a value obtained by averaging the azimuths of individual liquid crystal molecules.
[0047]
When an electric field E is applied from the back side of the paper to the front side of the paper as shown in FIG. 16, if the spontaneous polarization Ps of the liquid crystal molecules 5a is positive, the number of molecules of the liquid crystal director tilted to the upper right in the figure increases, and the average as the liquid crystal layer is increased. The optical axis also tilts in the upper right direction in the figure and functions as a birefringent plate. Above the threshold electric field at which the helical structure of the chiral smectic C phase can be solved, all the liquid crystal directors exhibit a tilt angle θ, and the optical axis becomes a birefringent plate inclined upward at an angle θ. The linearly polarized light incident from the left as extraordinary light is shifted upward in parallel. Here, when the refractive index in the major axis direction of the liquid crystal molecules is ne, the refractive index in the minor axis direction is no, and the thickness (gap) of the liquid crystal layer 5 is d, the shift amount S is represented by the following equation (for example, , "Crystal Optics", Japan Society of Applied Physics, edited by Optical Society, p.198).
S = [(1 / no) ² − (1 / ne) ² ] Sin (2θ) · d
÷ [2 ((1 / ne) ² sin ² θ + (1 / no) ² cos ² θ)] Equation 1
[0048]
Similarly, when the voltage applied to the electrodes is inverted and an electric field is applied to the back side of the paper as shown in FIG. 17, if the spontaneous polarization of the liquid crystal molecules is positive, the liquid crystal director tilts to the lower right in the figure and the optic axis lowers. It functions as a birefringent plate inclined at an angle θ to the side. The linearly polarized light incident from the left as extraordinary light is shifted downward in parallel. By reversing the direction of the electric field, an optical path deflection amount of 2S is obtained.
[0049]
FIGS. 16 and 17 show an ideal alignment state. However, when the thickness d of the liquid crystal layer 5 is increased in order to set the optical path deflection amount S to a large value, an alignment defect may occur. When the thickness of the liquid crystal layer is increased, the alignment regulating force from the alignment film becomes weaker toward the center of the layer, and the direction of the smectic layer is easily disturbed.
[0050]
FIG. 18 is a diagram for explaining the occurrence of alignment defects in the smectic C phase.
For example, as shown in FIG. 18 (a), at a certain temperature, the smectic A phase had a uniform vertical orientation, but upon cooling, the smectic A phase changed to a chiral smectic C phase, and the direction of the smectic layer at the center of the layer changed. As shown in FIG. 18B, there is a case where light is scattered due to disturbance. Although this mechanism is not clear, it is considered that a change in the distance between the smectic layers due to an increase in the tilt angle of the liquid crystal molecules and a force that distorts the smectic layer due to the generation of a helical pitch are generated. Further, even when a uniform chiral smectic C phase can be formed initially, orientation disturbance as shown in FIG. 18B may occur due to long-term driving, temperature change, external pressure, and the like.
[0051]
The smectic layer of the liquid crystal becomes discontinuous in the portion where the orientation is disturbed, and if the size or interval of the portion where the orientation is discontinuous is larger than the wavelength of transmitted light, the refractive index mismatch at the boundary surface causes the light Scattering occurs. It often looks cloudy due to forward scattering and back scattering of light. When cloudiness occurs in the liquid crystal layer of the optical path deflecting element, the transmittance is reduced, the transmitted light is generated in unnecessary directions, and the like, so that the light use efficiency, the SN ratio, and the contrast are undesirably reduced. The permissible amount of white turbidity varies depending on the purpose of the device using the optical path deflecting element, but when viewed as an optical element, the transmittance is 80% or more, and the MTF (modulation transfer function) at a spatial frequency of 50 lp / mm is 80%. As described above, the MTF is preferably 50% or more at a spatial frequency of 100 lp / mm.
[0052]
Here, the transmittance refers to the amount of light before passing through the liquid crystal layer when the parallel light from the white laser light source is emitted in the normal direction of the liquid crystal layer and passing through the liquid crystal layer, and the emission from the light source after passing through the liquid crystal layer. It means the ratio to the amount of light traveling in the direction.
MTF stands for the amount of light when the CCD receives an image of a black and white test pattern of a predetermined spatial frequency, whose density changes in a sine curve shape in a predetermined direction using an optical microscope, after passing through a liquid crystal layer. This is a value calculated from the maximum value and the minimum value.
[0053]
In general, it is difficult to uniformly control the alignment of the liquid crystal layer 5 having a chiral smectic C phase, and various studies have been made in the past. This was for a dielectric liquid crystal element. In a surface-stable ferroelectric liquid crystal device, homogeneous alignment is performed between substrate gaps that are thinner than the helical pitch of the chiral smectic C phase. Deterioration of the alignment appears as a difference in the direction in which the smectic layer is formed. When the transmitted light is observed in the crossed Nicols of the plate, the alignment defect portion is observed as a difference in light and dark portions.
[0054]
On the other hand, the amount of deflection of the optical path is proportional to the thickness of the liquid crystal layer. Therefore, in the optical path deflecting element of the present invention, the thickness of the liquid crystal layer is reduced from several μm to obtain an amount of optical path deflection of several μm to several tens μm. It is characterized in that it is set to a relatively thick thickness of several hundred μm. However, the maximum thickness is 1 mm or less. In particular, in order to obtain a shift amount of about half the pixel pitch of the image display element, the thickness of the liquid crystal layer is about 50 to 100 μm.
[0055]
In the ferroelectric liquid crystal having such a thick homeotropic alignment and having a chiral smectic C phase, the above-described white turbidity phenomenon may occur. Although the correlation between the occurrence of white turbidity and the physical property value of the liquid crystal material is not clear, it is considered that the helical pitch of the chiral smectic C phase, the amount and type of the chiral agent, and the like influence. In the present invention, the thickness of the ferroelectric liquid crystal layer of the homeotropically aligned chiral smectic C layer is preferably 10 μm or more. However, few examples have proposed such a structure as a practical element, There are no suggestions for.
[0056]
FIG. 17 shows a stable state after the liquid crystal molecules are inverted and realigned. However, during the inversion of the liquid crystal molecules, the alignment state is temporarily disturbed, and transient light scattering occurs. FIG. 19 shows a model of transient light scattering.
FIG. 19 is a view showing an inclined state of liquid crystal molecules in the optical path deflecting element, similarly to FIGS.
[0057]
Above the threshold electric field at which the helical structure of the chiral smectic C phase can be dissolved, the liquid crystal molecules are uniformly aligned as shown in FIG. When the applied electric field is inverted in a shorter time than the response time of the liquid crystal from this state, the liquid crystal molecules start to be inverted along the cone-shaped virtual plane shown by C in FIG. At this time, it is presumed that there is a region that rotates clockwise and a region that starts rotating counterclockwise as shown in FIG. It is considered that transient light scattering occurs at the interface between the domains having different rotation directions. Thereafter, as shown in FIG. 19C, when the liquid crystal molecules are realigned in a state of being uniformly inclined to the opposite side, the light scattering disappears.
[0058]
In order to reduce the transient light scattering, at least a part of the liquid crystal molecules in the liquid crystal layer is rotated in a cone-shaped virtual plane in the smectic layer by the reversal of the electric field direction to reverse the alignment direction as shown in FIG. It is effective to control the rotation direction of each inverted liquid crystal molecule in the same direction as in (d). As a method of controlling the rotation direction of the liquid crystal molecules, there are a method of giving directivity to the alignment direction of the liquid crystal layer itself, and a method of applying an electric field or a magnetic field from the outside.
[0059]
Giving the liquid crystal layer itself of the optical path deflecting element of the present invention directivity in the alignment direction means that the optical axis of the liquid crystal layer in the absence of an electric field is inclined with respect to the layer normal of the liquid crystal layer. is there. Since the tilt direction of the liquid crystal molecules during the optical path deflection operation is orthogonal to the direction of the driving electric field, in order to control the rotation direction of the liquid crystal molecules, the optic axis when no electric field is applied to the layer normal to the liquid crystal layer. Therefore, it is necessary to be inclined in the direction of the driving electric field. The method of giving directivity to the alignment direction of the liquid crystal layer itself and tilting the optical axis in the absence of an electric field with respect to the layer normal of the liquid crystal layer includes rubbing of a vertical alignment film, polymer or gel in the liquid crystal layer. Formation of a tissue by an agent or the like can be applied.
[0060]
The present invention has been made to solve these problems. Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view of an optical path deflecting element for describing a first embodiment of the present invention.
In the figure, reference numeral 5b denotes a fibrous or mesh-like structure made of an inorganic material or an organic material.
FIG. 1A is intended to solve the problem described with reference to FIG. 18. FIG. 1A shows a state where the temperature is somewhat high and the liquid crystal layer 5 exhibits a smectic A phase. () Shows a state in which the temperature has dropped and the liquid crystal layer 5 has transitioned to a chiral smectic C phase.
[0061]
In the present embodiment, as shown in FIG. 1, the liquid crystal layer 5 contains a fibrous or network-like structure 5b made of an inorganic material or an organic material to stabilize the orientation of the smectic phase. At this time, a liquid crystal material may be impregnated between the two glass substrates 2 and 2 in a space of a fibrous or mesh-like structure formed in advance. In this case, a glass fiber, a carbon nanotube, a porous stretched polymer, or the like can be used as the structure. It is desirable that the diameter of the fiber structure be equal to or smaller than the wavelength of the transmitted light so that the structure in the liquid crystal layer 5 does not cause light scattering.
Alternatively, a polymer material or a gelling agent may be injected between the two glass substrates 2 in a state where the polymer material or the gelling agent is previously mixed in the liquid crystal material. The structure and content of the polymer material are optimized such that the polymer material is dispersed in the liquid crystal molecules in a chain or three-dimensional network structure.
In the state of the smectic A phase having relatively good orientation as shown in FIG. 1 (a), the polymer material is uniformly dispersed in the horizontal and vertical directions of the smectic layer, and the orientation stability of the layer structure of the smectic phase is improved. Can be done.
[0062]
By cooling from this state, the orientation stability can be increased even after the transition to the chiral smectic C phase as shown in FIG. At this time, the content of the polymer material or the gelling agent is preferably in the range of about 0.5% by weight to 10% by weight. If the amount is smaller than this, the effect of stabilizing the layer structure of the smectic phase is reduced, and if it is larger, the electric and optical characteristics of the liquid crystal layer are deteriorated. By optimizing the content and molecular weight of the polymer material or the gelling agent, the alignment state in the bulk of the liquid crystal layer is stabilized, and the generation of alignment defects can be prevented.
[0063]
In order to dissolve a polymer material directly in a liquid crystal material as shown in FIG. 1A, the material may be limited due to the compatibility of both materials, the compatibility with a solvent, and the like. It is difficult to uniformly disperse a polymer material that separates from a liquid crystal material. Further, since a ferroelectric liquid crystal material that exhibits a smectic layer at about room temperature has a high viscosity, it becomes difficult to uniformly disperse a polymer material.
[0064]
Therefore, it is preferable that a monomer or a prepolymer is uniformly dissolved in the liquid crystal and injected into the device, and then a uniform polymer material is formed by a polymerization reaction. As the polymerization reaction, thermal polymerization or photopolymerization can be used depending on the type of polymerization initiator. In the case of thermal polymerization, it is necessary to heat the liquid crystal material to a relatively high temperature, but since the liquid crystal material itself has temperature characteristics such as phase transition, optimize the thermal polymerization initiation temperature and the phase transition temperature of the liquid crystal. And the choice of materials tends to be limited.
Even when a gelling agent is used, the shape of the formed tissue is determined by the type and concentration of the gelling agent, so that the selection range of the gelling agent suitable for stabilizing the liquid crystal layer tends to be limited. is there.
[0065]
In the second embodiment of the present invention, the tissue 5b is a polymer material in which at least one of a monomer and a prepolymer is formed by photopolymerization. In this case, after injecting a mixture of a liquid crystal material and a monomer or a prepolymer into the optical path deflecting element, a uniform polymer structure is formed in the liquid crystal layer by exposure treatment at a relatively low temperature such as room temperature by a photopolymerization initiator. Can be formed. The polymer structure has a chain or three-dimensional network structure depending on the number of functional groups in the monomer used.
In general, a chain is referred to as a polymer chain or a polymer chain, and a three-dimensional network structure is referred to as a polymer network.
[0066]
In the case of this embodiment, since a mixture of low molecular weight materials is used, it is easier to adjust a uniform liquid crystal mixture than in a case where a polymer material is directly dissolved in a liquid crystal material, and the alignment stability is effectively improved. Can be made. In the case of photopolymerization, the molecular weight and the phase separation structure of the polymer structure can be controlled by controlling the combination of the two parameters of light intensity and irradiation time even if the same monomer is used. Therefore, there is an advantage that the range of selection of the monomer material can be widened as compared with the thermal polymerization and the gelling agent.
[0067]
When a polymer structure is formed by a polymerization reaction in a liquid crystal layer as described above, it is necessary that the liquid crystal layer before polymerization is oriented in a uniform smectic phase. Therefore, in the third embodiment of the present invention, the liquid crystal layer is polymerized and cured in a temperature range in which the liquid crystal layer exhibits a homeotropic alignment and exhibits a smectic A phase. The smectic A phase appears in a higher temperature region than the chiral smectic C phase, has no tilt angle of liquid crystal molecules with respect to the normal direction of the smectic layer, and has no helical structure. By polymerizing in the temperature range of the smectic A phase, a polymer structure can be generated in a uniform smectic layer state as shown in FIG.
[0068]
Thereafter, when the temperature is lowered and the phase transitions to the chiral smectic C phase, even if the smectic layer interval changes or a strain occurs due to the generation of the helical structure, it is controlled as shown in FIG. The generation of alignment defects can be prevented. As described above, even when a liquid crystal material having poor orientation of the chiral smectic C phase is used, a uniform polymer structure can be formed and the orientation can be improved.
However, there is a liquid crystal material whose orientation is not so good at the stage of the smectic A phase. Further refinement is needed for such materials.
[0069]
In order to improve the orientation of the chiral smectic C phase before polymerization, in the fourth embodiment of the present invention, as in the case of the optical path deflecting operation, a state in which an AC electric field is applied in a direction parallel to the substrate surface in the liquid crystal layer. To cool from the temperature of the smectic A phase to the temperature of the chiral smectic C phase, and polymerize and cure in the state where an AC electric field is applied. Generally, in a light deflecting element using a liquid crystal material, the light deflecting operation is often set to several tens Hz to several hundreds Hz in accordance with the viscoelasticity and dielectric characteristics of the liquid crystal material, but the response of the liquid crystal molecules is not sufficient. By applying a relatively high-frequency electric field that is too late, the vertical orientation of the chiral smectic C phase is improved.
[0070]
The frequency of the AC electric field for stabilizing the alignment also varies depending on the viscoelasticity and dielectric properties of the liquid crystal material, but is preferably between about 50 Hz and 10 KHz. If the frequency is lower than this, the liquid crystal layer behaves like a DC electric field, causing the liquid crystal layer to flow. At frequencies higher than this, liquid crystal molecules cannot respond at all, and the effect of improving the alignment does not appear. In particular, at least including a temperature range in which a transition is made from a relatively high temperature smectic A phase to a chiral smectic C phase, that is, by applying the AC electric field during the cooling process, alignment defects in the chiral smectic C phase are reduced. It can be effectively prevented.
[0071]
The reason for this effect is not clear, but by giving a symmetrical vibration in the horizontal direction of the layer of liquid crystal molecules, the liquid crystal molecules do not tilt to one side, that is, the smectic layer is curved and alignment defects are reduced. It is presumed that this is prevented from occurring. Further, it is more preferable to use a liquid crystal having a negative dielectric anisotropy because an electrostatic force for vertically aligning the liquid crystal molecules by a high-frequency horizontal electric field also works. Therefore, even in a liquid crystal material that originally has poor alignment of the chiral smectic C phase, a chiral smectic C phase having no alignment defect at a relatively low temperature can be temporarily formed, and by polymerizing and curing the polymer material in this state. In addition, the alignment state without alignment defects can be stabilized for a long time.
[0072]
FIG. 2 is a schematic diagram showing a state in which polymer polymerization is performed while applying a DC electric field in a direction different from that during the light deflection operation.
In the fifth embodiment of the present invention, in a temperature range showing a chiral smectic C phase, in a process of polymerization into a polymer, a direction parallel to the substrate surface in the liquid crystal layer and orthogonal to a direction in which an electric field is applied during an optical path deflection operation. Then, by polymerizing and curing while a DC electric field E 'is temporarily applied, a polymer structure which receives a regulating force in a state where liquid crystal molecules are inclined in one direction is formed.
As shown in FIG. 2 (a), the polymerization reaction is performed in a state where an electric field is applied in a direction different from the direction of the electric field during normal operation by temporarily installing an external electrode 4 'or the like, so that the light deflection direction is increased. A stable tilt direction of the liquid crystal molecules is set to a direction different from the above.
FIG. 2B is a view showing a state when an electric field in one direction is applied to the optical path deflecting element obtained by this method.
[0073]
When the applied electric field is reversed from the state shown in FIG. 2B, the applied electric field transiently becomes 0. At this time, the tilt direction of the liquid crystal molecules is affected by the regulating force of the polymer, and FIG. Return to the state. From this state, the light is directed in the tilt direction corresponding to the inverted electric field. That is, since the asymmetry is generated in the ease of rotation of the liquid crystal molecules, when the tilt direction of the liquid crystal molecules is reversed during the optical path deflecting operation, the rotation direction is controlled in one direction, and a transient light scattering phenomenon due to a variation in the rotation direction is caused. Reduced.
By optimizing the amount and the material of the polymer to be added, it is possible to reduce the side effect that the light deflection direction is shifted and the response time is lengthened. In this case, since only one stable tilt direction can be set, the rotational motion of the liquid crystal molecules at the time of inversion is always a reciprocating motion via the stable tilt direction.
[0074]
FIG. 3 is a schematic diagram showing a state of a liquid crystal layer when a liquid crystalline polymer is used as a polymer material.
In the figure, reference numeral 5c indicates a liquid crystalline polymer.
In the sixth embodiment of the present invention, a polymer material having a liquid crystal skeleton as a partial structure is used. The liquid crystalline polymer may be a main chain type having a mesogen group of a liquid crystal skeleton in a main chain or a side chain type bonded to a side chain. Further, a composite type containing a main chain and a side chain may be used. By using a liquid crystalline monomer or a liquid crystalline prepolymer having good compatibility with the ferroelectric liquid crystal of the chiral smectic C phase as the host material, the polymer material 5c after polymerization can be uniformly phase-separated. Since the polymer chains are uniformly dispersed, the orientation can be uniformly stabilized. In addition, since the polymer material itself has orientation and optical anisotropy, it is possible to prevent a decrease in birefringence and a deterioration in an optical path deflection phenomenon due to the introduction of a polymer component.
[0075]
Various materials can be used as the liquid crystal monomer, but it is preferable that the liquid crystal monomer exhibit a nematic phase at room temperature in order to improve compatibility with the host liquid crystal. Further, it is preferable to use the following liquid crystalline monomer depending on the orientation and the response of the chiral smectic C phase as the host liquid crystal.
In a seventh embodiment of the present invention, the monomer contains a liquid crystal diacrylate or a liquid crystal dimethacrylate having a methylene spacer between a liquid crystal skeleton and two acryloyloxy groups. Here, both are collectively described as liquid crystalline di (meth) acrylate.
As the liquid crystalline di (meth) acrylate, a material represented by the following general formula (1) can be used.
[0076]
Embedded image

[0077]
(1) In the formula, X represents a hydrogen atom or a methyl group, n represents an integer of 0 or 1, and the 6-membered rings A, B, and C are each independently any of the structures shown in the formula (2) Represents
[0078]
Embedded image

[0079]
m represents an integer of 1 to 4; ¹ And Y ² Are each independently a single bond, -CH ₂ CH ₂ -, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO-, -C≡C-, -CH = CH-, -CF = CF-,-(CH ₂ ) ₄ -, -CH ₂ CH ₂ CH ₂ O-, -OCH ₂ CH ₂ CH ₂ -, -CH = CH-CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH = CH-, Y ³ Represents a single bond, -O-, -COO-, -OCO-, and a and b represent an integer of 1 to 20.
Preferred examples include those represented by the following structural formula (3).
[0080]
Embedded image

[0081]
Such liquid crystalline di (meth) acrylate forms a three-dimensional network structure when polymerized, and can effectively stabilize the alignment state of the liquid crystal layer. For example, among liquid crystals capable of forming a chiral smectic C phase, an optical path that achieves both alignment and responsiveness by combining with a liquid crystal having particularly large tilt angles and spontaneous polarization, and having poor alignment stability but excellent high-speed response. A deflection element is obtained.
[0082]
In an eighth aspect of the present invention, the monomer contains a liquid crystal acrylate having a methylene spacer between a liquid crystal skeleton and one acryloyloxy group, or a liquid crystal methacrylate. Here, both are collectively described as liquid crystal (meth) acrylate. The liquid crystalline (meth) acrylate having a methylene spacer forms a side chain type liquid crystal polymer when polymerized.
As the liquid crystal (meth) acrylate, a material represented by the following general formula (4) can be used.
[0083]
Embedded image

[0084]
(4) In the formula, Z represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, and other symbols are represented by the formula (1). It has the same definition as the symbol.
Preferred examples include those represented by the following structural formula (5).
[0085]
Embedded image

[0086]
In such materials, the liquid crystal skeleton is relatively easy to move because the liquid crystal skeleton is bonded to the polymer main chain via the methylene spacer, and the effect of stabilizing the alignment state is relatively weak, but the resistance to the inversion operation of the liquid crystal is low. There is an advantage that the response is small and the deterioration of the response is small. For example, among liquid crystals capable of forming a chiral smectic C phase, in particular, the tilt angle and spontaneous polarization are small, and the alignment stability is relatively good, but the combination of the liquid crystal and the responsiveness achieves both the alignment property and the responsiveness. An optical path deflecting element is obtained.
[0087]
In a ninth embodiment of the present invention, the monomer contains a liquid crystal (meth) acrylate having no methylene spacer between the liquid crystal skeleton and one acryloyloxy group. As the liquid crystal (meth) acrylate, a material represented by the following general formula (6) can be used.
[0088]
Embedded image

[0089]
Each symbol in the equation (6) has the same definition as the symbol shown in the equation (4).
In particular, in the general formula (6), X represents a hydrogen atom, n represents 0, and the 6-membered rings A and C each independently represent a 1,4-phenylene group or a 1,4-transcyclohexyl group. , Y ¹ Represents a single bond or -C≡C-; ³ Represents a single bond, and Z is preferably a material representing a halogen atom, a cyano group or an alkyl group having 1 to 20 carbon atoms.
[0090]
Further, more preferred examples include those represented by the following structural formulas (7) and (8). Further, a mixture of these may be used. For example, a mixture obtained by mixing (7) and (8) by 50 parts by weight shows a nematic phase at room temperature and is easy to handle.
[0091]
Embedded image

[0092]
Embedded image

[0093]
In such a liquid crystalline (meth) acrylate having no methylene spacer, since the liquid crystal skeleton is directly bonded to the polymer main chain when polymerized, the movement of the liquid crystal skeleton is restricted, and the liquid crystal skeleton directly contributes to the alignment stability. Although the alignment stability is relatively strong, the effect of stabilizing the alignment state is relatively strong because the polymer chain itself is also easy to move.However, the resistance to the inversion operation of the liquid crystal is relatively small, and the responsiveness is deteriorated. There is an advantage of being small. For example, by combining a liquid crystal capable of forming a chiral smectic C phase with a liquid crystal having particularly poor alignment stability and responsiveness, an optical path deflecting element having both alignment and responsiveness can be obtained.
[0094]
In the first to ninth embodiments, only the linearly polarized light in the optical path deflection direction, that is, the polarization direction parallel to the tilt direction of the liquid crystal molecules when an electric field is applied, receives the optical path deflection, and the linearly polarized light perpendicular to the polarization direction. Keep going straight. Therefore, when unpolarized light is incident, the emitted light contains a component that is not deflected, and the contrast with respect to the presence or absence of optical path deflection is reduced.
[0095]
FIG. 4 is a diagram showing an outline of an optical path deflecting device having means for regulating the polarization direction of light incident on the optical path deflecting element in a specific direction.
In the figure, reference numeral 8 denotes a linear polarizing plate.
In the tenth embodiment of the present invention, as shown in FIG. 4, there is provided a polarization direction regulating means for setting the polarization direction of the light incident on the optical path deflecting element to a direction orthogonal to the direction of the electric field applied in the liquid crystal layer. In other words, control means for linearly polarizing light in a direction parallel to the shift direction of the optical path deflection is provided. As the polarization direction regulating means, a linear polarization plate 8 can be used. The linear polarizing plate 8 is set on the incident surface side of the optical path deflecting element 1 so that the polarization direction of the linear polarizing plate 8 is parallel to the longitudinal direction of the electrode 4. Even when the incident light is non-polarized light, light components that are not affected by the optical path deflection due to the tilt of the liquid crystal molecules are cut, so that the optical switching by the optical path deflection can be performed reliably.
[0096]
FIG. 5 is a schematic diagram for explaining a configuration of a four-way shift device using a combination of optical path deflecting elements.
In the figure, reference numeral 9 denotes a four-way shift device, 10 denotes a first optical path deflecting element, 11 denotes a half-wave plate, and 12 denotes a second optical path deflecting element.
An eleventh embodiment of the present invention will be described with reference to FIG. The present embodiment is an apparatus in which another optical path deflecting element is combined with the optical path deflector configured as in the above-described embodiment by changing the shift direction. A half-wave plate as a polarization plane rotating means is interposed between the two optical path deflecting elements. In FIG. 5, spacers, alignment films, and the like are omitted.
[0097]
The first and second optical path deflecting elements 10 and 12 are arranged in series in the light traveling direction with the directions of electric field generated by the respective electrode pairs 4 and 4 orthogonal to each other. A 手段 wavelength plate 11 is provided as a means. Here, an example in which the electric field generation directions are orthogonal is illustrated, but the direction is not limited to the orthogonal direction and may be set to a predetermined angle.
As the half-wave plate 11, a commercially available crystal plate or liquid crystal film for visible light can be applied as it is. The plane of polarization can also be rotated using a twisted nematic (hereinafter abbreviated as TN) liquid crystal cell.
[0098]
The light beam L previously adjusted to linearly polarized light is deflected by the first optical path deflecting element 10 on the front stage side with respect to the light traveling direction, passes through one of the optical paths in the left and right two directions L1 and L2, and then becomes a half-wave plate. By rotating the polarization direction by 90 ° by 11 to become the polarization direction in the vertical direction, the polarization direction is deflected by the second optical path deflecting element 12 in the subsequent stage, and L1 takes one of the optical paths in the two vertical directions L11 and L12, Further, L2 also takes one of the optical paths in the two directions L21 and L22 in the vertical direction, and as a result, passes through any one of the optical paths in four directions.
Here, an example in which the deflection direction is rotated by 90 ° is illustrated. However, the direction is not limited to 90 °, and a predetermined direction may be used in which the polarization direction emitted from the first optical path deflection element matches the deflection direction of the second optical path deflection element. It is good also as an angle.
[0099]
FIG. 6 is a timing chart showing an example of driving of the four-way shift device.
FIG. 6A is a diagram illustrating the drive timing of the first optical path deflector, and FIG. 6B is a diagram illustrating the drive timing of the second optical path deflector. By adjusting the timing of the two as shown in the figure, shifts in four directions are sequentially selected around one direction.
[0100]
FIG. 7 is a schematic diagram of an image display device using an optical path deflecting element.
In the figure, reference numeral 21 is an LED lamp as a light source, 22 is a diffusion plate, 23 is a condenser lens, 24 is a transmissive liquid crystal panel as an image display element, 25 is a projection lens, 26 is a screen, 27 is a light source drive unit, 28 Denotes a drive unit of a transmission type liquid crystal panel, 29 denotes an optical path deflecting unit, and 30 denotes a drive unit of a four-way shift device.
A twelfth embodiment of the present invention will be described with reference to FIG. This embodiment shows an example of application to an image display device. In FIG. 7, in the traveling direction of light emitted from the light source LED lamps 21 arranged in a two-dimensional array toward the screen 26, a diffusion plate 22, a condenser lens 23, a transmissive liquid crystal panel 24 as an image display element, an image A projection lens 25 as an optical member for observing a pattern is arranged in order.
[0101]
On the optical path between the transmission type liquid crystal panel 24 and the projection lens 25, a four-way shift device 29 functioning as a pixel shift element is interposed, and is connected to the drive unit 30. As the optical path deflecting means 29, the above-described four-way shift device or the like is used.
[0102]
Illumination light emitted from the light source 31 controlled by the light source drive unit 27 becomes illumination light uniformed by the diffusion plate 22, and is transmitted by being controlled by the condenser lens 23 in synchronization with the illumination light source 21 by the liquid crystal drive unit 28. The liquid crystal panel 24 is illuminated. The illumination light spatially modulated by the transmission type liquid crystal panel 24 enters the optical path deflecting means 29 as image light, and the image light is shifted by a predetermined distance in the pixel arrangement direction by the optical path deflecting means 29. This light is enlarged by a projection lens 25 and projected on a screen 26.
[0103]
By displaying the image pattern with the display position shifted in accordance with the deflection of the optical path for each of a plurality of subfields obtained by temporally dividing the image field by the optical path deflecting means 29, the apparent appearance of the transmissive liquid crystal panel 24 is displayed. Are displayed with the number of pixels multiplied. As described above, the shift amount by the optical path deflecting unit 29 is set to の of the pixel pitch because the image is doubled in the pixel arrangement direction of the transmissive liquid crystal panel 24. By correcting the image signal for driving the transmissive liquid crystal panel 24 by the shift amount according to the shift amount, an apparently high-definition image can be displayed.
[0104]
At this time, since the light deflecting element as in each of the above-described embodiments is used as the light path deflecting means 29, the light use efficiency is improved, and a bright and high quality image is provided to the observer without increasing the load on the light source. Images can be provided. By performing the optical path deflection control by the electric field application direction and the electric field intensity by the electrode pairs 4 and 4 in the optical path deflection element 1, an appropriate pixel shift amount is maintained and a good image can be obtained.
[0105]
(Example 1)
FIG. 8 is a view showing a test apparatus for confirming the operation of the optical path deflecting element.
In the figure, reference numeral 1 'denotes an empty cell, and 31 denotes a power supply for applying an electric field.
A homeotropic alignment film having a thickness of 600 ° was formed on the surface of a glass substrate having a thickness of 1 mm. An empty cell 1 ′ as shown in FIG. 8 was prepared in which an aluminum electrode sheet having a thickness of 80 μm, a width of 1.0 mm and a length of 12 mm was used as a spacer and an electrode, and an electrode pair was arranged in parallel so that the effective area was 1 cm wide.
Next, 1 part by weight of a commercially available photopolymerization initiator, 1 part by weight of a liquid crystal acrylate composition comprising 50 parts by weight of each of the compounds represented by the formulas (7) and (8), and a ferroelectric liquid crystal A ferroelectric liquid crystal composition comprising 99% by weight of CS1029 "(manufactured by Chisso) was prepared.
[0106]
With the empty cell 1 'and the ferroelectric liquid crystal composition heated to about 80 ° C, the ferroelectric liquid crystal composition was injected into the empty cell 1'. The cell is cooled to a temperature at which the liquid crystal exhibits a smectic A phase, and the cell is maintained at 60 mJ / cm while maintaining the vertical alignment state of the smectic A phase. ² UV light was applied. Thereafter, the resultant was cooled to room temperature and sealed with an adhesive to obtain a polymer-stabilized vertical alignment ferroelectric liquid crystal cell as the optical path polarizing element 1. A power supply 31 composed of a pulse generator and a high-speed amplifier was connected to the electrode pairs 4 and 4 to form a test device.
[0107]
When a conoscopic image of the liquid crystal layer in the effective area of the optical path deflecting element was observed at room temperature in the absence of an electric field, a cross-shaped and an annular image were observed at the center. Therefore, it was confirmed that the optical axis was perpendicular to the liquid crystal layer under no electric field. In this state, the tilt direction of the liquid crystal molecules has a helical structure that rotates with respect to the direction perpendicular to the substrate surface, and the average optical axis is observed as the direction perpendicular to the substrate surface, which is the direction of the helical axis. .
[0108]
Next, when a rectangular wave voltage of ± 3 kV and 1 Hz was applied to the electrode pairs 4 and 4 from the power supply 31, the positions of the cross and the ring of the conoscopic image were reciprocated vertically at 1 Hz. When the inclination angle of the optical axis was calculated from the NA value of the microscope objective lens, the refractive index of the liquid crystal, and the shift amount of the cross position, it was about 20 degrees.
[0109]
An opening corresponding to a rectangular wave having a spatial frequency of 100 lp / mm was illuminated from behind with a mask pattern having a square of 5 μm, and the transmitted light was observed through an optical path deflecting element 1 incorporated in the apparatus shown in FIG. It is observed that the position of the mask pattern is shifted by operating the optical path deflecting element 1. By observing the state of this shift with a high-speed camera equipped with a microscope, the amount of optical path shift and its response time were measured. Observation with a high-speed camera (time resolution 40,500 frames / sec) was performed while applying a rectangular wave voltage of ± 3 kV, 120 Hz to the electrode pairs 4 and 4 from the power supply 31. The shift amount was 7 μm, and the response required for the movement was obtained. The time was 1 msec, and the shift amount and the high-speed response without any practical problems were exhibited.
[0110]
Even if this operation was performed continuously for 8 hours, no change was observed in the alignment state of the liquid crystal layer. Further, no change was observed in the alignment state of the liquid crystal layer even when the driving was turned on / off repeatedly. Therefore, a stable optical path deflecting element was obtained without deterioration in the optical path deflecting operation.
[0111]
(Comparative Example 1)
Example 1 was repeated except that the thickness of the electrode / spacer aluminum sheet was reduced to 65 μm and a polymer-stabilized liquid crystal cell using a liquid crystalline diacrylate composition was not used. When "CS1029" (manufactured by Chisso) was used as the liquid crystal material, the inclination angle of the optical axis measured by a conoscope was 25 degrees. In the measurement by the high-speed camera, the shift amount was 9 μm, and the response time required for the movement was 0.8 msec.
When this operation was continuously performed for 8 hours, a slight cloudiness was generated in the liquid crystal layer in the effective area. When the drive was repeatedly turned on / off in this state, a cloudy portion grew. In this state, the light transmittance of the liquid crystal element decreased, and light scattering occurred.
By heating this element to 80 ° C. and recooling it, it was possible to return to the initial state of good orientation, but a stable optical path deflecting element could not be obtained.
[0112]
(Example 2)
A liquid crystal cell was prepared in the same manner as in Example 1, except that the ferroelectric liquid crystal composition and the operation and conditions during photopolymerization were changed as follows. The thickness of the liquid crystal layer was set to 65 μm.
1 part by weight of a commercially available photopolymerization initiator, 0.5% by weight of a liquid crystalline diacrylate composition of the compound represented by the formula (3), and 99.5% by weight of a ferroelectric liquid crystal “CS2005” (manufactured by Chisso) Was prepared.
CS2005 does not show the smectic A phase, and the orientation of the smectic C phase is poor, but the spontaneous polarization and the tilt angle are relatively large.
[0113]
While the empty cell and the ferroelectric liquid crystal composition were heated to about 80 ° C., the ferroelectric liquid crystal composition was injected into the empty cell. When cooling was performed with an AC voltage of ± 2000 V, 200 Hz applied to the electrode pair of this cell, cloudiness due to alignment disorder was temporarily generated near the transition temperature from the chiral nematic phase to the chiral smectic C phase, but gradually. The orientation was restored. Thereafter, even when cooled to room temperature, the vertically oriented state of the chiral smectic C phase having relatively good orientation was maintained. 60mJ / cm in that state ² UV light was applied. Thereafter, the resultant was sealed with an adhesive to obtain a polymer-stabilized vertically aligned ferroelectric liquid crystal cell, that is, an optical path polarizing element 1. This optical path deflecting element was incorporated in a test apparatus shown in FIG.
[0114]
When a conoscopic image of the liquid crystal layer was observed at room temperature in the effective area of the optical path deflecting element in the absence of an electric field, a cross-shaped and an annular image were observed at the center. Therefore, it was confirmed that the optical axis was perpendicular to the liquid crystal layer under no electric field. Next, when a rectangular wave voltage of ± 3 kV and 1 Hz was applied to the electrode pair from the power supply, the positions of the cross and the ring of the conoscopic image were reciprocated vertically at 1 Hz. When the inclination angle of the optical axis was calculated from the NA value of the objective lens of the microscope, the refractive index of the liquid crystal, and the shift amount of the cross position, it was about 25 degrees.
[0115]
As in Example 1, the mask pattern having an opening of 5 μm square was illuminated from the back surface, and the transmitted light was observed through the optical path deflecting element of this example incorporated in the test apparatus shown in FIG. It is observed that the position of the mask pattern is shifted by operating the optical path deflecting element. By observing the state of this shift with a high-speed camera equipped with a microscope, the amount of optical path shift and its response time were measured. Observation with a high-speed camera (time resolution: 40,500 frames / sec) was performed while applying a rectangular wave voltage of ± 3 kV and 120 Hz from the power supply to the electrode pair. The shift amount was 7 μm, and the response time required for the movement was 1 msec. Yes, the shift amount and the high-speed response which are practically acceptable were shown.
[0116]
When a liquid crystal diacrylate compound such as the compound represented by the formula (3) is polymerized, the effect of stabilizing the alignment of the liquid crystal layer is considered to be very large because a three-dimensional network structure is formed. Since the effect of restricting the switching operation is great, there is a concern that the response speed may be reduced. Therefore, as in the present embodiment, the spontaneous polarization and the tilt angle are large, and the high-speed response is excellent. The stability was also improved.
[0117]
Even if this operation was performed continuously for 8 hours, no change was observed in the alignment state of the liquid crystal layer. Further, no change was found in the alignment state of the liquid crystal layer even when the driving was repeatedly turned on / off. Therefore, a stable optical path deflecting element was obtained without deterioration in the optical path deflecting operation.
[0118]
(Comparative Example 2)
Example 2 was repeated except that no AC electric field was applied after liquid crystal injection. Since the liquid crystal of Example 2 had poor orientation, white turbidity due to disordered alignment began to occur near the transition temperature from the chiral nematic phase to the chiral smectic C phase during cooling, and the white turbidity remained at room temperature. Even if photopolymerization was performed in this state, the state was fixed while the orientation was disturbed, and thus no polymer structure was formed by polymerization.
[0119]
(Example 3)
An empty cell similar to that of Example 1 was created. The thickness of the liquid crystal layer was set to 65 μm.
Next, a ferroelectric material comprising 1 part by weight of a commercially available photopolymerization initiator, 1% by weight of a liquid crystal acrylate composition of the compound represented by the formula (5), and 99% by weight of ferroelectric liquid crystal "CS1024" (manufactured by Chisso). A liquid crystal composition was prepared. CS1024 alone has relatively good orientation and a sufficient response speed, but there is room for further improvement in long-term operation stability.
[0120]
While the empty cell and the ferroelectric liquid crystal composition were heated to about 80 ° C., the ferroelectric liquid crystal composition was injected into the empty cell. The cell was cooled to a temperature at which the liquid crystal exhibited a smectic A phase, and the cell was kept at 60 mJ / cm while maintaining the vertical alignment state of the smectic A phase. ² UV light was applied. Thereafter, the mixture was cooled to room temperature and sealed with an adhesive to obtain a polymer-stabilized vertical alignment ferroelectric liquid crystal cell. This optical path deflecting element was incorporated in a test apparatus shown in FIG.
[0121]
When a conoscopic image of the liquid crystal layer was observed at room temperature in the effective area of the optical path deflecting element in the absence of an electric field, a cross-shaped and an annular image were observed at the center. Therefore, it was confirmed that the optical axis was perpendicular to the liquid crystal layer under no electric field. Next, when a rectangular wave voltage of ± 3 kV and 1 Hz was applied to the electrode pair from the power supply, the positions of the cross and the ring of the conoscopic image were reciprocated vertically at 1 Hz. When the inclination angle of the optical axis was calculated from the NA value of the objective lens of the microscope, the refractive index of the liquid crystal, and the shift amount of the cross position, it was about 25 degrees.
[0122]
As in Example 1, a mask pattern having an opening of 5 μm square was illuminated from the back surface, and the transmitted light was observed through an optical path deflecting element incorporated in the test apparatus shown in FIG. It is observed that the position of the mask pattern is shifted by operating the optical path deflecting element. By observing the state of this shift with a high-speed camera equipped with a microscope, the amount of optical path shift and its response time were measured. Observation with a high-speed camera (time resolution: 40,500 frames / sec) was performed while applying a rectangular wave voltage of ± 3 kV and 120 Hz from the power supply to the electrode pair. The shift amount was 7 μm, and the response time required for the movement was 1. 5 msec, indicating a shift amount and a high-speed response that are practically no problem.
[0123]
When a liquid crystalline acrylate compound having a methylene spacer, such as the compound represented by the formula (5), is polymerized, a side-chain type liquid crystal polymer is formed, so that the effect of stabilizing the alignment of the liquid crystal layer is considered to be relatively small. However, since the effect of restricting the switching operation of the liquid crystal molecules is small, the effect on the response speed is small. Therefore, by combining with a liquid crystal material having relatively good alignment stability as in this embodiment, long-term alignment stability can be maintained while ensuring a practical response speed.
[0124]
Even if this operation was performed continuously for 8 hours, no change was observed in the alignment state of the liquid crystal layer. Further, no change was found in the alignment state of the liquid crystal layer even when the driving was repeatedly turned on / off. Therefore, a stable optical path deflecting element was obtained without deterioration in the optical path deflecting operation.
[0125]
(Comparative Example 3)
Example 3 was carried out in the same manner as in Example 3 except that a polymer-stabilized liquid crystal cell using a liquid crystal acrylate composition was not used. According to the measurement by the high-speed camera, the shift amount was 9 μm, and the response time required for the movement was 1.3 msec.
When this operation was continuously performed for 8 hours, a slight cloudiness was generated in the liquid crystal layer in the effective area. When the drive was repeatedly turned on / off in this state, a cloudy portion grew. In this state, the light transmittance of the device decreased, and light scattering occurred.
By heating this element to 80 ° C. and recooling it, it was possible to return to the initial state of good orientation, but a stable optical path deflecting element could not be obtained.
[0126]
(Example 4)
FIG. 9 is a diagram showing an optical path deflector using an optical path polarizing element having a second electrode pair.
In the same figure, reference numeral 32 indicates a second electrode.
An empty cell 1 'similar to that of Example 1 was formed except that a second electrode pair 4 ", 4" was provided as shown in FIG. The same ferroelectric liquid crystal composition as in Example 1 was injected, and cooled in a state where an AC voltage was applied as in Example 2, to form a chiral smectic C phase having good orientation even at room temperature. Next, the optical path deflecting device shown in FIG. 9 was assembled, and photopolymerization was similarly performed in a state where a DC electric field of 200 V / mm was applied from the second power source 32 to the second pair of electrodes 4 ″ and 4 ″. Thereafter, the resultant was sealed with an adhesive to obtain a polymer-stabilized vertical alignment ferroelectric liquid crystal cell. The direction of the electric field by the second pair of electrodes 4 ″ and 4 ″ is different from the direction of the electric field for driving the optical path deflection. As shown in FIG. 2, the spiral of the chiral smectic C phase is released and the liquid crystal molecules are not driven. It is considered that the polymer was stabilized in a state inclined to the surface.
[0127]
FIG. 10 is a schematic diagram showing a device for detecting the transmitted light of the optical path deflecting element.
In the figure, reference numerals 33 and 34 denote polarizing plates, and reference numeral 35 denotes a photodetector.
It is assumed that the optical path polarizing element 1 shown in the figure is used in a state of being incorporated in the optical path deflecting device shown in FIG. However, during actual use, no electric field is applied to the electrode pairs 4 ", 4", so the second power supply 32 is disconnected.
The optical path deflecting device shown in FIG. 9 using the optical deflecting element 1 prepared in Example 4 was incorporated in the device as shown in FIG. 10, and the intensity of transient light scattering time was measured. In the following description, reference numerals shown in FIG. 9 are also used.
FIG. 10A is a diagram showing a state in which a predetermined electric field is applied to the optical path polarizing element 1 by the power supply 31 shown in FIG. 9 and liquid crystal molecules are uniformly arranged. FIG. 10B is a diagram illustrating a state where the alignment of the liquid crystal molecules is transiently disturbed when the electric field is inverted.
[0128]
The unpolarized laser light L0 is made incident on the light deflector 1 through the polarizing plate 33 as vertically polarized light L1 in the figure. The polarization direction of the incident light L1 and the deflection direction of the light deflecting element 1 are arranged to coincide with each other, and a crossed Nicol polarizing plate 34 is arranged after the light deflecting element 1. As shown in FIG. 10A, when a predetermined electric field is applied to the optical path deflecting element 1, the liquid crystal molecules in the optical path deflecting element 1 are uniformly aligned, and an optical path shift phenomenon occurs. Since no disturbance occurs, the transmitted light L1 'does not pass through the polarizing plate 34 later. On the other hand, as shown in FIG. 10B, in a transient state when the electric field applied to the optical path deflecting element 1 is reversed, the polarization plane is also disturbed because the alignment of the liquid crystal molecules is disturbed, and the transmitted light L2 is scattered light. Then, light L3 having a polarization direction perpendicular to the paper surface, which leaks out of the polarizing plate 34 later, is generated. By detecting the intensity and time of the leaked light L3 with the photodetector 35, the intensity and time of transient light scattering can be measured.
[0129]
In the optical path deflecting element 1 shown in FIG. 10, a rectangular wave voltage of ± 2000 V, 100 Hz was applied from the first power supply 31 to the first pair of electrodes 4, 4, and the measurement was performed. Was 10 mV, and the detection time of leaked light was 1 msec. The state of the optical path shift under this driving condition is illuminated from the back side with a mask pattern having an opening of 5 μm square as in Example 1, and the transmitted light is passed through an optical path deflecting element shown in FIG. 9 with a high-speed camera equipped with a microscope. Observed.
[0130]
FIG. 11 is a diagram showing how the pattern of transmitted light moves.
In the figure, reference numeral 36 indicates the position of the pattern of transmitted light of the mask pattern. When the opening moves, the position 36 of the transmitted light pattern draws a slightly arc-shaped trajectory as shown in FIG. 11 from the first position 36a to the second position 36c via the intermediate point 36b. moved. Also, during the movement, the opening dots were observed with relatively good contrast. Therefore, the rotation direction at the time of inversion of the liquid crystal molecules is controlled to one direction, and transient light scattering due to the inversion is at a level where there is no problem. With this level of leakage light intensity and time, there is no practical problem with the actual optical path shift phenomenon. It was judged.
[0131]
(Comparative Example 4)
In the same manner as in Example 4, a similar measurement of transient light scattering was performed using a liquid crystal element which was subjected to photopolymerization without applying a DC electric field to the second electrode pair. The leakage light detection voltage was 20 mV, and the leakage light detection time was 1.5 msec. When the moving process of the opening was observed with a high-speed camera, a straight locus was drawn. In addition, it was observed that the aperture dots were blurred during the movement, causing transient light scattering. Since the rotation direction at the time of inversion of the liquid crystal molecules was not controlled, transient light scattering occurred due to the inversion. However, the generation time of the leakage light was relatively short, and it was judged that it was practically allowable.
[0132]
(Example 5)
A four-way shift device similar to FIG. 5 was created, and an image display device similar to FIG. 7 was configured. The reference numerals shown below correspond to the reference numerals shown in both figures. As the image display element 24, a 0.9 inch diagonal XGA (1024 × 768 dots) polysilicon TFT liquid crystal light valve was used. The pixel pitch is about 18 μm both vertically and horizontally. The aperture ratio of the pixel is about 50%. Further, a microlens array is provided on the light source side of the image display element 24 to increase the light collection rate of the illumination light. In this embodiment, a so-called field-sequential system is used in which an RGB three-color LED light source is used as the light source 21 and color display is performed by rapidly changing the color of light applied to the image display element 24 of the single liquid crystal panel. Has adopted.
[0133]
In the present embodiment, the frame frequency of image display is 60 Hz, and the subfield frequency is quadrupled to 240 Hz because of a four-fold pixel multiplication by pixel shift. To further divide one subframe into three colors, the image corresponding to each color is switched at 720 Hz. By turning on / off the LED light source 21 of the corresponding color in accordance with the display timing of the image of each color on the image display element 24 of the liquid crystal panel, the observer can see a full-color image.
The basic configuration of the optical path deflecting element 1 is the same as that of the first embodiment. In addition, an outside air blowing fan was provided, and the air path deflecting element 1 was air-cooled so that the temperature of the element became 25 ° C., which is the same as the outside temperature.
[0134]
Two sets of light path deflecting elements were used, the first light path deflecting element 10 on the incident side and the second light path deflecting element 12 on the outgoing side. The transparent electrode lines 4 are arranged so that their directions are orthogonal to each other and coincide with the arrangement direction of the pixels of the image display element 24. In this embodiment, the light emitted from the liquid crystal light valve of the image display element 24 is already linearly polarized light, and the polarization direction is arranged so as to coincide with the light path deflection direction of the first light path deflection element 10. In order to ensure the degree of polarization of light incident on the element, a linear polarizing plate was provided on the incident surface side of the optical path deflecting element 10 as a polarization direction regulating means.
[0135]
Further, a polarization plane rotating element 11 'is provided between the first and second optical path deflecting elements. The polarization plane rotator 11 'was formed by spin-coating a polyimide-based alignment material on two glass substrates (3 cm × 4 cm, 3 mm thick) to form an alignment film of about 0.1 μm. After the annealing treatment of the glass substrate, a rubbing treatment was performed. An empty cell was produced by making the rubbing surfaces face each other with a spacer having a thickness of 8 μm interposed between the two glass substrates, and bonding the two substrates so that the rubbing directions were orthogonal to each other. A material obtained by mixing an appropriate amount of a chiral material with a nematic liquid crystal having a positive dielectric anisotropy was injected into the cell under normal pressure, thereby producing a TN liquid crystal cell in which the orientation of liquid crystal molecules was twisted by 90 degrees.
[0136]
Since this cell has no electrode, it functions simply as a polarization rotation element 11 '. Also, discharge between the aluminum electrodes of the optical path deflecting elements 10 and 12 is prevented. It was disposed between the two optical path deflecting means so that the rubbing direction of the light emitted from the first optical path deflecting element 10 and the rubbing direction of the incident surface of the polarization rotating element 11 'coincided. The polarization plane of the light emitted from the first optical path deflecting element 10 is rotated by 90 degrees by the polarization plane rotating element 11 ′, and coincides with the deflection direction of the second optical path deflecting element 12. An optical deflecting device 29 including the first optical path deflecting element 10, the polarization plane rotating element 11 ′, and the second optical path deflecting element 12 was installed immediately after the image display element 24.
[0137]
The optical path deflecting elements 10 and 12 are cooled to about 25 ° C. by a blower fan, and the voltage of the rectangular wave voltage for driving the optical path deflecting elements 10 and 12 is ± 3 kV (the average electric field is ± 300 V / mm) and the frequency is 120 Hz. The drive timing was set such that the phase of the rectangular wave applied to the optical path deflecting elements was shifted by 90 degrees as shown in FIG. 6 and the pixels were shifted in four directions. With this driving voltage, the optical path shift amount is about 9 μm, and the pixels are shifted by half a pixel for display.
[0138]
By rewriting the subfield image displayed on the image display element 24 at 240 Hz, an image with a frame frequency of 60 Hz in which the apparent number of pixels was doubled in both the vertical and horizontal directions could be displayed. The pixel shift amount was uniform from the center to the end of the image, and a high-definition image was obtained. The switching time of the optical path deflecting elements 10 and 12 was about 1 msec, and sufficient light use efficiency was obtained. No flicker was observed. After 8 hours of continuous operation, high-definition images were maintained.
[0139]
(Comparative Example 5)
An optical rotator as a light path deflecting element 1 using a twisted nematic liquid crystal cell having a liquid crystal layer thickness of 10 μm; ₃ Example 5 was repeated except that an element obtained by knitting the birefringent element was used. 5 and 7 are referred to for the same reference numerals as in the fifth embodiment.
Using two sets of optical path deflecting elements 10 and 12, a polarization plane rotating element 11 'similar to that of Example 5 was provided between them. The optical path deflecting elements 10 and 12 are cooled to about 25 ° C. by a blower fan, and the voltage of the rectangular wave voltage for driving the optical path deflecting elements 10 and 12 is set to ± 10 V and the frequency is set to 120 Hz. The drive timing was set such that the phase of the applied rectangular wave was shifted by 90 degrees and the pixels were shifted in four directions.
[0140]
With this driving voltage, the optical path shift amount is about 9 μm, and pixels are shifted by half a pixel for display. However, the response speed of the optical path deflecting elements 10 and 12 is 15 msec. could not. Therefore, by driving the optical path deflecting elements 10 and 12 at 60 Hz and rewriting the subfield image displayed on the image display element 24 at 120 Hz, the frame frequency in which the apparent number of pixels in the vertical and horizontal directions is doubled each time. A 30 Hz image could be displayed. However, flicker and the like were observed. Further, the wavelength dependence of the optical path shift amount was large, and ghost pixels occurred outside the shift position.
[0141]
【The invention's effect】
Since the liquid crystal layer of the chiral smectic C phase forming the homeotropic alignment filled between the substrates contains a fibrous or network-like structure, the alignment state is stabilized, and the alignment is not disturbed even in repeated use. .
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an optical path deflecting element for describing a first embodiment of the present invention.
FIG. 2 is a schematic diagram showing a state in which polymer polymerization is performed while applying a DC electric field in a direction different from that in the light deflection operation.
FIG. 3 is a schematic diagram showing a state of a liquid crystal layer when a liquid crystalline polymer is used as a polymer material.
FIG. 4 is a diagram showing an outline of an optical path deflecting device having means for restricting the polarization direction of light incident on the optical path deflecting element to a specific direction.
FIG. 5 is a schematic diagram for explaining a configuration of a four-way shift device using a combination of optical path deflecting elements.
FIG. 6 is a timing chart showing an example of driving of the four-way shift device.
FIG. 7 is a schematic diagram of an image display device using an optical path deflecting element.
FIG. 8 is a diagram showing a test apparatus for confirming the operation of the optical path deflecting element.
FIG. 9 is a diagram showing an optical path deflector using an optical path polarizing element having a second electrode pair.
FIG. 10 is a schematic diagram showing a device for detecting transmitted light of an optical path deflecting element.
FIG. 11 is a diagram showing a state of movement of a transmitted light pattern.
FIG. 12 is a diagram schematically showing a cross section of an optical path deflecting element.
FIG. 13 is a diagram showing an example of a different electrode configuration.
FIG. 14 is a diagram schematically showing a direction of an electric field and a tilt direction of liquid crystal molecules in the configuration shown in FIG.
FIG. 15 is a schematic diagram showing a state when an electric field is inverted from the state of FIG.
FIG. 16 is a diagram schematically illustrating the alignment state of liquid crystal molecules and the principle of optical path deflection.
FIG. 17 is a diagram schematically showing a state where the electric field is inverted in FIG. 16;
FIG. 18 is a diagram for explaining occurrence of alignment defects in a smectic C phase.
FIG. 19 is a diagram showing an inclined state of liquid crystal molecules in the optical path deflecting element as in FIGS. 14 and 15;
[Explanation of symbols]
1, 10, 12 optical path polarizing element
2 substrate
3 Vertical alignment film
4 electrodes
5 Liquid crystal layer
7 Spacer
8 Linear polarizing plate
9 Four-way shift device
11 1/2 wave plate

Claims (20)

A pair of transparent substrates, a liquid crystal layer capable of forming a chiral smectic C phase having a homeotropic alignment filled between the substrates, and an electrode for forming a driving electric field in a direction parallel to the substrate surface in the liquid crystal layer A direction of a driving electric field applied to the electrode pair, thereby switching an orientation direction of liquid crystal molecules, and switching a tilt direction of an optical axis with respect to a layer normal of the liquid crystal layer, so that light incident on the substrate surface is changed. An optical path deflecting element for switching an output optical path from the substrate surface, wherein the liquid crystal layer has a fibrous or mesh-like structure. 2. The optical path deflecting element according to claim 1, wherein the thickness of the liquid crystal layer is 10 μm or more. 3. The optical path deflecting device according to claim 1, wherein the optical axis in the absence of an electric field is inclined in a direction of a driving electric field with respect to a layer normal of the liquid crystal layer. The optical path polarizing element according to any one of claims 1 to 3, wherein the tissue is formed by polymerizing at least one of a monomer and a prepolymer with a photopolymerization initiator. element. The optical path deflecting element according to claim 4, wherein the liquid crystal layer containing the tissue has a light transmittance of 80% or more during the photopolymerization. The optical path deflecting element according to claim 4, wherein the tissue is polymerized in a temperature range showing a smectic A phase having homeotropic alignment. The optical path polarizing element according to claim 4, wherein the texture is a temperature of a chiral smectic C phase from a temperature of a smectic A phase in a state where an AC electric field is applied in a direction parallel to the substrate surface in the liquid crystal layer. An optical path deflecting element, wherein the optical path deflecting element is cooled down to a temperature and polymerized in a state where the AC electric field is applied. The optical path polarizing element according to claim 4, wherein the tissue is polymerized in a temperature range showing a chiral smectic C phase while applying a DC electric field in a direction different from that in the light deflection operation. Optical path deflecting element. 9. The optical path deflecting element according to claim 1, wherein the tissue has a liquid crystal skeleton as a partial structure. 10. The optical path polarizing element according to claim 9, wherein the structure is formed by polymerizing a liquid crystalline di (meth) acrylate having a methylene spacer between a liquid crystal skeleton and two acryloyloxy groups. Deflection element. 10. The optical path polarizing element according to claim 9, wherein the texture is formed by polymerizing a liquid crystalline (meth) acrylate having a methylene spacer between a liquid crystal skeleton and one acryloyloxy group. element. 10. The optical path polarizing element according to claim 9, wherein the texture is formed by polymerizing a liquid crystal (meth) acrylate having no methylene spacer between a liquid crystal skeleton and one acryloyloxy group. element. 13. The optical path polarizing element according to claim 1, wherein a polarization direction of light incident on the optical path deflecting element is set to a direction parallel to a direction in which the optical axis is projected on a substrate surface. An optical path deflecting element comprising a direction regulating means. 14. The optical path deflecting device according to claim 13, wherein a polarization plane rotating means for rotating a polarization plane of the outgoing light of the optical path deflecting element in a predetermined direction, and a second optical path having the outgoing light after the rotation of the polarization plane as incident light. A polarizing element, wherein the normal direction of the liquid crystal layer of the optical path polarizing means and the liquid crystal layer normal direction of the second optical path deflecting means are arranged so that the electric field directions of the two optical path deflecting means are at a predetermined angle. Characteristic optical path deflecting element. An image display device comprising the optical path deflecting device according to claim 1, wherein a plurality of pixels capable of controlling light according to image information are two-dimensionally arranged, and a light source for illuminating the image display device. And an illuminating device, an optical device for observing an image pattern displayed on an image display element, display driving means for forming an image field by a plurality of time-divided subfields, and a deflection state of an optical path for each subfield An image display device which displays an image pattern whose display position is shifted according to the above, thereby increasing the apparent number of pixels of the image display element. A pair of transparent substrates are arranged in parallel at a predetermined interval, an electrode pair forming a driving electric field is arranged in a direction parallel to the substrate surface, and a chiral smectic C phase forming a homeotropic orientation can be formed between the substrates. In the method of manufacturing an optical path deflecting element for forming a liquid crystal layer, the liquid crystal contains a monomer or a prepolymer, and in a state where the liquid crystal is injected between the substrates to form a homeotropic alignment state, at least the monomer or the prepolymer A method for producing an optical path deflecting element, wherein one is polymerized with a photopolymerization initiator. 17. The method for manufacturing an optical path deflecting element according to claim 16, wherein a transmittance of the liquid crystal layer when performing polymerization by the light is 80% or more. 18. The method of manufacturing an optical path deflecting element according to claim 16, wherein the liquid crystal layer is polymerized in a temperature range showing a smectic A phase forming homeotropic alignment. The method for manufacturing an optical path deflecting element according to claim 16, wherein a temperature of a smectic A phase to a temperature of a chiral smectic C phase in a state where an AC electric field is applied in a direction parallel to the substrate surface in the liquid crystal layer. A method for manufacturing an optical path deflecting element, comprising cooling and polymerizing in a state where the AC electric field is applied. 18. The method of manufacturing an optical path deflecting element according to claim 16, wherein the polymerization is performed in a temperature range showing a chiral smectic C phase while applying a DC electric field in a direction different from that during the light deflection operation. A method for manufacturing a deflection element.

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