JP4072743B2

JP4072743B2 - Optical deflector and display device using the same

Info

Publication number: JP4072743B2
Application number: JP32409298A
Authority: JP
Inventors: 隆之井関; 泰弘菅野; 実紀雄奥村; 慎悟柳生
Original assignee: Victor Company of Japan Ltd
Current assignee: Victor Company of Japan Ltd
Priority date: 1998-11-13
Filing date: 1998-11-13
Publication date: 2008-04-09
Anticipated expiration: 2018-11-13
Also published as: JP2000147419A

Description

【０００１】
【発明の属する技術分野】
本発明は、レーザビーム等の光を反射させて光偏向を行う光偏向器、及び、この光偏向器を用いた表示装置に関する。
【０００２】
【従来の技術】
電子写真式複写機、レーザビームプリンタ、バーコードリーダ等の光学機器の走査装置や、光ディスクのトラッキング制御装置の光偏向装置や、レーザ光をスキャニングして映像を投影する表示装置などには光偏光器が使用されている。
【０００３】
一般に、機械的に光偏向を行う光偏光器としては、回転多面鏡（ポリゴンミラー）、騒動型反射鏡（ガルバノミラー）等があるが、ガルバノミラー型のものはポリゴンミラー型のものに比べて機構が小型化でき、又、最近の半導体プロセス技術ではシリコン基板を用いたマイクロミラーの試作例なども報告されており、さらに小型化、軽量化、低コスト化が期待できる。
【０００４】
このようなガルバノミラー型の光偏向器の従来例が図１４〜図１７と図１８とにそれぞれ示されている。
【０００５】
図１４は第１従来例の光偏向器の分解斜視図、図１５はこの光偏向器の概略側面図である。図１４及び図１５において、ベース５０には左右一対の立設部５１、５２が設けられ、この一対の立設部５１，５２上には振動体５３が配置されている。振動体５３は外枠部５４と、この外枠部５４の開口部５４ａに配置された反射ミラー部５５と、この反射ミラー部５５の略重心を通る軸上の位置で反射ミラー部５５と外枠部５４とを連結する一対の支持部５６，５６とから一体的に構成されている。外枠部５４の左右両端部分が一対の立設部５１，５２上に固定されており、一対の支持部５６，５６は外枠部５４に対して反射ミラー部５５を支持すると共に、この反射ミラー部５５を振動させるための捩りバネの機能を備えている。
【０００６】
又、ベース５０上には左右一対の固定電極５７，５８が配置され、この一対の固定電極５７，５８は反射ミラー部５５の左右両端部に対向する位置に配置されている。この一対の固定電極５７，５８の相手側の電極として反射ミラー部５５が構成され、各固定電極５７，５８と反射ミラー部５５との間には各切替スイッチＳＷ１，ＳＷ２を介して選択的に電圧を印加できるように構成されている。尚、反射ミラー部５５は外枠部５４と一対の支持部５６，５６を介して接続されているため、反射ミラー部５５への電圧印加は外枠部５４に印加すれば良い。
【０００７】
上記構成において、一方の固定電極５７と反射ミラー部５５との間に電圧が印加されたときには反射ミラー部５５の左側が静電力により吸引されて反射ミラー部５５が一対の支持部５６，５６を揺動中心軸ＣＬ（図１５に示す）として反時計方向に回転し、又、他方の固定電極５８と反射ミラー部５５との間に電圧が印加されたときには反射ミラー部５５が静電力により吸引されて反射ミラー部５５の右側が一対の支持部５６，５６を揺動中心軸ＣＬ（図１５に示す）として時計方向に回転する。従って、切替スイッチＳＷ１，ＳＷ２を交互にオン・オフ制御し、一対の固定電極５７，５８に交互に電圧を印加することによって反射ミラー部５５が左右に揺動するものである。この反射ミラー部５５に照射された光は、反射ミラー部５５の揺動によって反射角が変更され、これによって光偏向される。
【０００８】
図１８は第２従来例の光偏向器の分解斜視図である。図１８において、ベース５０上には補助ベース部材６０が固定され、この補助ベース部材６０の開口部６０ａ内に反射ミラー部５５が配置されている。この反射ミラー部５５の略重心を通る軸上の両側と外補助ベース部材６０との間が一対の支持部５６，５６で連結されている。反射ミラー部５５はこの一対の支持部５６，５６を中心として揺動自在に構成されている。又、反射ミラー部５５の両外端部には櫛歯部６１が構成されており、この各櫛歯部６１に対向する補助ベース部６０の位置で、且つ、これより低い位置には固定電極５７，５８がそれぞれ固定されている。この一対の固定電極５７，５８の各反射ミラー部５５側には前記櫛歯部６１に噛み合う櫛歯部６２が構成されている。
【０００９】
上記構成において、一方の固定電極５７と反射ミラー部５５との間に電圧が印加されたときには反射ミラー部５５の左側が静電力により吸引されて反射ミラー部５５が一対の支持部５６，５６を揺動中心軸として反時計方向に回転し、又、他方の固定電極５８と反射ミラー部５５との間に電圧が印加されたときには反射ミラー部５５の右側が静電力により吸引されて反射ミラー部５５が一対の支持部５６，５６を揺動中心軸として時計方向に回転する。従って、前記第１従来例と同様に、一対の固定電極５７，５８に交互に電圧を印加することによって反射ミラー部５５が左右に揺動するものである。
【００１０】
【発明が解決しようとする課題】
しかしながら、前記第１及び第２従来例においては、以下に述べるような問題があった。
【００１１】
即ち、第１従来例において、反射ミラー部５５を高速で揺動させるためには、反射ミラー部５５の重量がより軽い方が望ましい。ここで、図１６で示すように、軽量化のために反射ミラー部５５の厚みｔを薄くすると、光反射面が撓んでしまう等の不都合が生じ剛性に問題がでる。
【００１２】
又、反射ミラー部５５の偏向角（振れ角）を大きくするには、図１７に示すように、反射ミラー部５５と固定電極５７，５８とのギャップ間隔を大きく設定する必要がある。しかし、静電力は、ギャップの２乗に反比例するので、必要な駆動力を得るには非常に大きな電圧を必要とする。
【００１３】
一方、前記第２従来例においては、第１従来例と異なり、櫛歯部６１，６２の高さを大きく設定すれば偏向角を大きく取ることができ、櫛歯の数を多くすれば低電圧で大きな駆動力が得られる。しかしながら、反射ミラー部５５の両外端部に櫛歯部６１を設けるために、反射ミラー部５５が大型化するのは避けられない。反射ミラー部５５が大型化すると、反射ミラー部５５の共振周波数が低下するため、高速で揺動させることができない。特に、偏向角を大きく取るため、又は、低電圧で大きな駆動力を得るため、櫛歯部６１，６２の高さを大きく設定したり、櫛歯数を多くすることは反射ミラー部５５の重量の増量となり、さらなる共振周波数の低下を招く。
【００１４】
そこで、本発明は、前記した課題を解決すべくなされたものであり、低い駆動電力の下でも高速で、且つ、広偏向角で揺動することができると共に、反射ミラー部の剛性にも問題が生じない光偏向器及びこれを用いた表示装置を提供することを目的とする。
【００１５】
【課題を解決するための手段】
上記目的を達成するために、本発明の特徴は、表面に光反射面を有する反射ミラー部と、この反射ミラー部をベースに対して揺動自在に支持する一対の支持部と、前記ベースの反射ミラー部側に配置された一対の固定電極とを有し、この各固定電極と前記反射ミラー部との間に電圧を印加して静電力で前記反射ミラー部が前記一対の支持部を揺動中心軸として揺動する光偏向器において、前記反射ミラー部は、その裏面に、前記揺動中心軸に直交する方向に延在する溝及び突起部を有するミラー側櫛歯部を備え、前記各固定電極は、前記反射ミラー部側に、前記ミラー側櫛歯部に噛み合い可能な突起部及び溝を有する電極側櫛歯部を備え、前記ミラー側櫛歯部及び前記電極側櫛歯部は、それぞれ、溝に対する突起部の高さが、前記揺動中心軸から遠ざかるに従って低くなるように構成したことである。
【００１６】
本発明の他の特徴は、表面に光反射面を有する反射ミラー部と、この反射ミラー部をベースに対して揺動自在に支持する一対の支持部と、前記ベースの反射ミラー部側に配置された一対の固定電極とを有し、この各固定電極と前記反射ミラー部との間に電圧を印加して静電力で前記反射ミラー部が前記一対の支持部を揺動中心軸として揺動する光偏向器において、前記反射ミラー部は、その裏面に、前記揺動中心軸に直交する方向に延在する溝及び突起部を有するミラー側櫛歯部と、前記揺動中心軸に沿って形成され、前記支持部同士を前記突起部を介して連接するリブ部と、を備え、前記各固定電極は、前記反射ミラー部側に、前記ミラー側櫛歯部に噛み合い可能な突起部及び溝を有する電極側櫛歯部を備えてなることである。
【００１８】
【発明の実施の形態】
以下、本発明の実施形態を図面に基づいて説明する。
【００１９】
図１〜図４は本発明の第１実施形態を示し、図１（Ａ）は光偏向器１Ａの分解斜視図、図１（Ｂ）は光偏向器１Ａの概略側面図、図２は光偏向器１Ａの斜視図、図３は光偏向器１Ａの概略側面図、図４は反射ミラー部７の裏面側の斜視図である。
【００２０】
図１〜図４において、光偏向器１Ａのベース２は偏平長方形状を有し、このベース２の全外周端には立設部３が一体的に突出形成されており、この立設部３上に振動体５が配置されている。
【００２１】
この振動体５は、方形状の外枠部６と、この外枠部６の開口部６ａ内に配置された反射ミラー部７と、この反射ミラー部７の略重心を通る軸上の位置で反射ミラー部７と外枠部６とを連結する一対の支持部８，８とから一体的に構成されている。そして、外枠部６が立設部３上に固定されており、反射ミラー部７は一対の支持部８，８を揺動中心軸ＣＬ（図１，図３に示す）として揺動自在に構成されている。反射ミラー部７の表面には光反射膜が膜付けされて光反射面７ａが形成されている。
【００２２】
また、図４に詳しく示すように、反射ミラー部７の裏面には前記揺動中心軸ＣＬに直交する方向に延びる溝９ａと突起部９ｂとから成るミラー側櫛歯部９が一体的に形成されている。この反射ミラー部７のミラー側櫛歯部９に対向するベース２上の位置には左右一対の固定電極１０，１１が配置され、この一対の固定電極１０，１１の上面側にも溝１２ａと突起部１２ｂとから成る電極側櫛歯部１２が一体的に形成されている。そして、ミラー側櫛歯部９と電極側櫛歯部１２とは、一方の溝９ａ，１２ａと他方の突起部９ｂ，１２ｂとが互いに対向する位置関係、つまり、互いに噛み合うように配置されている。各固定電極１０，１１と反射ミラー部７との間には各切替スイッチＳＷ１，ＳＷ２を介して選択的に電圧を印加できるよう構成されており、各切替スイッチＳＷ１，ＳＷ２を交互にオン・オフ制御し、一対の固定電極１１，１２に交互に電圧を印加するように構成されている。
【００２３】
また、前記反射ミラー部７はその厚みが薄く形成され、且つ、ミラー側櫛歯部９及び電極側櫛歯１２の高さ、具体的には溝９ａ，１２ａと突起部９ｂ，１２ｂとの噛み合いストロークは広い偏向角を得られるように高く形成されている。つまり、反射ミラー部７は全体として軽量で、共振周波数が高く構成されている。
【００２４】
上記構成において、図１（Ｂ）に示すように、一方の固定電極１０と反射ミラー部７との間に電圧が印加されたときには反射ミラー部７の左側が静電力により吸引されて反射ミラー部７が一対の支持部８を揺動中心軸ＣＬとして反時計方向に回転し、又、図３に示すように、他方の固定電極１１と反射ミラー部７との間に電圧が印加されたときには、一方の固定電極１０の吸引力が解除され、捩じられた一対の支持部８が弾性復帰力により反射ミラー部７を元の位置に戻そうとすると共に、反射ミラー部７の右側が静電力により吸引されて反射ミラー部７が一対の支持部８を揺動中心軸ＣＬとして時計方向に回転する。従って、切替スイッチＳＷ１，ＳＷ２を交互にオン・オフ制御されると、一対の固定電極１０，１１に交互に電圧を印加することによって反射ミラー部７が左右に揺動するものである。この反射ミラー部７に照射された光は、反射ミラー部７の揺動によって反射角が変更され、これによって光偏向される。尚、反射ミラー部７への電圧印加は、この反射ミラー部７を接続している外枠部６に印加している。
【００２５】
ここで、反射ミラー部７の駆動力は、ミラー側櫛歯部９と電極側櫛歯部１２との間に発生する静電力によって得られ、且つ、双方のギャップ間隔が揺動位置にかかわらず狭く一定であるため、低い電圧で大きな駆動力を得ることができる。尚、駆動力の大きさの程度は下記に詳述する。
【００２６】
そして、ミラー側櫛歯部９と電極側櫛歯部１２との高さは、所望の偏向角を得るのに必要な高さに設定され、且つ、反射ミラー部７は軽量で共振周波数が高く構成されているため、低い電圧の下でも高速で、且つ、大きな偏向角で揺動させることができる。特に、反射ミラー部７を共振周波数で振動させると、反射ミラー部７が最大変位で振動するため、低電力で大きな回転力を得ることができる。
【００２７】
又、反射ミラー部７はミラー側櫛歯部９の突起部９ｂが強度を高めるリブとしても機能するため、厚みを薄く形成しても光反射面７ａが撓む等の剛性に問題が生じない。反射ミラー部７は、その裏面側にミラー側櫛歯部９を設け、反射ミラー部７の表面全体を光反射面７ａとして構成できるため、光反射面７ａとして必要最少限の大きさに設定すれば良く、この点からも軽量化が図られる。
【００２８】
次に、本発明の櫛歯電極の場合と第１従来例の平面電極の場合とにおける静電力の大きさを比較する。一般的に、固定電極と可動部である反射ミラー部７との間に電圧Ｖを印加した場合に発生する静電力Ｆは、ギャップ間隔をｇ、ギャップ間の誘電率をε、電極の奥行きをＷ、電極の幅をＬとすると、図５（Ａ）のような櫛歯電極の場合には、１つの櫛歯面に働く静電力は、Ｆ＝εＶ²Ｗ／２ｇとなる。図５（Ｂ）のような平行平面電極の場合には、Ｆ＝εＶ²ＷＬ／２ｇ²となる。
【００２９】
平行平面電極の場合、静電力はギャプ間隔の２乗で大きくなるが、反射ミラー部７の偏向角を大きく取ろうとすると、このギャップ間隔を大きくする必要がある。従って、大きな静電力を得ることが困難になる。これに対し、櫛歯電極の場合、反射ミラー部７はギャップに対して平行に移動するので、ギャップ間隔は一定である。従って、ギャップ間隔は可能な限り小さくできるため、大きな静電力を得ることができる。さらに、櫛歯の数ｎを複数にすることができるので、静電力は上式のさらに２ｎ倍になる。
【００３０】
次に、双方の場合を具体的な数値を代入して比較する。図６に示すように、反射ミラー部７の大きさを２ｍｍ角とすると、上式においてＷ＝１ｍｍ、Ｌ＝２ｍｍとなる。又、偏向角を±１０度とすると、櫛歯電極の場合、櫛歯の数をそれぞれの電極に５０個（４０μｍピッチ）ずつ、ギャップ間隔ｇを２μｍとすると、一組の櫛歯に働く静電力ｆは、ｆ＝εＶ²×１／２×（２×１０^-4）＝２．５×１０²×εＶ²となる。一組の櫛歯には静電力の働く面が２面あり、又、櫛歯が５０個あるので、全体としての静電力Ｆは、Ｆ＝２×５０ｆ＝２．５×１０⁵×εＶ²となる。
【００３１】
平行平面電極の場合、偏向角が±１０度のとき反射ミラー部７の最端部が１７６μｍ変位するので、それがギャップ間隔ｇとなる。従って、静電力Ｆは、Ｆ＝εＶ²×１×２／２×（１７６×１０^-4）²＝３．２×１０³×εＶ²となる。
【００３２】
以上より、櫛歯電極にした場合、同じ電圧で約８０倍の静電力が得られることになる。さらに、櫛歯電極の場合は、製造方法により櫛歯の数を増やしたり、ギャップ間隔を狭くしたりすることも可能であり、より大きな静電力を得ることも可能である。
【００３３】
図７は本発明の第２実施形態を示す光偏向器１Ｂの裏面側の斜視図である。この第２実施形態にあって前記第１実施形態と同一構成箇所は図面に同一符号を付してその説明を省略し、異なる構成のみを説明する。
【００３４】
即ち、図７に示すように、反射ミラー部７の裏面側であって、且つ、一対の支持部８，８を通る揺動中心軸ＣＬ上の位置には溝９ａを設けずに、隣接する突起部９ｂ間を連結するリブ２０が形成されている。この箇所は静電力の作用には無関係の箇所であるため、前記第１実施形態と比べて同様な大きさの静電力が得られると共に、リブ２０が反射ミラー部７の強度をさらに強くするため、より剛性の向上となるものである。
【００３５】
図８及び図９は本発明の第３実施形態を示し、図８及び図９はそれぞれ光偏向器１Ｃの概略側面図である。図８及び図９において、この第３実施形態にあって前記第１実施形態と比較してミラー側櫛歯部９と電極側櫛歯部１２との構成のみが相違し、他の構成は同一であるため、ミラー側櫛歯部９と電極側櫛歯部１２との構成のみを説明し、その他の構成は図面に同一符号を付してその説明を省略する。
【００３６】
即ち、この第３実施形態では、ミラー側櫛歯部９と電極側櫛歯部１２との揺動方向（揺動中心軸ＣＬに直交する方向）の長さが反射ミラー部７の揺動方向の長さよりも短く形成されている。このようにすることによって、反射ミラー部７の自由端（外側端部）が固定電極１０，１１又はベース２に衝突するまでの角度が大きくできるため、偏向角を大きくすることができる。図９は一方の固定電極１０と反射ミラー部７間に電圧を印加した状態を示し、第１実施形態の図３の場合に比べて揺動角が大きくなっていることが分かる。
【００３７】
図１０及び図１１は本発明の第４実施形態を示し、図１０及び図１１は光偏向器１Ｄの概略側面図である。図１０及び図１１において、この第４実施形態にあって前記第１実施形態と比較してミラー側櫛歯部９と電極側櫛歯部１２との構成のみが相違し、他の構成は同一であるため、ミラー側櫛歯部９と電極側櫛歯部１２との構成のみを説明し、その他の構成は図面に同一符号を付してその説明を省略する。
【００３８】
即ち、この第４実施形態では、ミラー側櫛歯部９と電極側櫛歯部１２との高さが、揺動中心軸ＣＬから遠ざかるに従って低くなるように形成されている。このようにすることによって、反射ミラー部７と固定電極１０，１１との間隔を狭く設定しても反射ミラー部７の自由端（外側端部）が固定電極１０，１１に衝突するまでの角度が大きくできるため、偏向角を大きくすることができる。図１１は一方の固定電極１０と反射ミラー部７間に電圧を印加した状態を示し、第１実施形態の図３の場合に比べて揺動角が大きくなっていることが分かる。
【００３９】
以上、前記第１〜第４実施形態によれば、低電圧の下でも高速で、且つ、広偏向角の揺動を行うことができるが、各光偏向器１Ａ〜１Ｄの内部を陽極接合等の方法を用いて真空封止すれば反射ミラー部７の揺動に対し空気抵抗の影響をなくすことができ、より高速に揺動可能となり好ましい。
【００４０】
図１２は、上記各光偏向器１Ａ〜１Ｄを用いた表示装置の概略構成図である。図１２において、レーザ光源３０より発射されたレーザ光は、水平走査用光偏向子３１に照射される。水平走査用光偏向子３１は水平周波数に同期して反射ミラー部が揺動され、この揺動によって反射光が水平方向に走査される。ここで反射されたレーザ光は垂直走査用光偏向子３２に照射される。この垂直走査用光偏向子３２は垂直周波数に同期して反射ミラー部が揺動され、この揺動によって反射光が垂直方向に走査される。ここで反射されたレーザ光がスクリーン３３に照射される。
【００４１】
水平走査用光偏向子３１として上記各光偏向器１Ａ〜１Ｄを用いられており、上記したように高速で、且つ、広偏向角で揺動できるため、数十ｋＨｚの走査周波数に同期させて揺動させることができる。もちろん、垂直走査用光偏向子３２にも上記各光偏向器１Ａ〜１Ｄを用いても良い。
【００４２】
図１３は、上記各光偏向器１Ａ〜１Ｄを用いた他の表示装置の概略構成図である。図１３において、レーザ光源３０より発射されたレーザ光は、水平走査用光偏向子３１に照射される。水平走査用光偏向子３１は水平周波数に同期して反射ミラー部が揺動され、この揺動によって反射光が水平方向に走査される。ここで反射されたレーザ光は垂直走査用光偏向子３２に照射される。この垂直走査用光偏向子３２は垂直周波数に同期して反射ミラー部が揺動され、この揺動によって反射光が垂直方向に走査される。ここで反射されたレーザ光が集束レンズ３４を通って光アドレス型空間変調素子３５に照射される。光アドレス型空間変調素子３５はこの光情報を書き込み、これを表面側に明度、輝度等を増幅して液晶で表示する。
【００４３】
一方、ランプ３６からの光は赤外線カットフィルタ３７、レンズ３８、波長フィルタ３９を通ってポラリゼーション・ビームスプリッタ４０に入射され、この反射光が光アドレス型空間変調素子３５に照射される。この光アドレス型空間変調素子３５を反射した光は再びポラリゼーション・ビームスプリッタ４０に入射され、ここを透過した光がレンズ４１を介してスクリーン３３に照射される。
【００４４】
水平走査用光偏向子３１として上記各光偏向器１Ａ〜１Ｄを用いられており、上記したように高速で、且つ、広偏向角で揺動できるため、数十ｋＨｚの走査周波数に同期させて揺動させることができる。もちろん、垂直走査用光偏向子３２にも上記各光偏向器１Ａ〜１Ｄを用いても良い。
【００４５】
尚、前記実施形態によれば、光偏向器の適用例として表示装置を示したが、電子写真式複写機、レーザビームプリンタ、バーコードリーダ等の光学機器の走査装置や、光ディスクのトラッキング制御装置の光偏向装置等にも適用できることはもちろんである。
【００４６】
【発明の効果】
以上説明したように、本発明によれば、反射ミラー部が一対の支持部を揺動中心軸として静電力による揺動する光偏向器において、反射ミラー部の裏面には前記揺動中心軸に直交する方向に延びる溝と突起部とから成るミラー側櫛歯部を形成し、一対の固定電極の前記反射ミラー部側には、前記ミラー側櫛歯部に噛み合い可能な溝と突起部とから成る電極側櫛歯部を形成したので、ミラー側櫛歯部と電極側櫛歯部との高さを、所望の偏向角を得るのに必要な高さに設定してもミラー側櫛歯部と電極側櫛歯部とのギャップ間隔が変化せず、又、反射ミラー部の裏面側にミラー側櫛歯部を形成したことから反射ミラー部の大きさを光反斜面に必要な最少限の大きさに形成すればよいこと、及び、ミラー側櫛歯部の突起部が強度リブとして機能することから反射ミラー部の厚みを薄く形成しても剛性を維持できることから反射ミラー部を軽量で共振周波数を高いものに構成できるため、低い電圧の下でも高速で、且つ、大きな偏向角で揺動させることができると共に、反射ミラー部の剛性にも問題が生じない。
【００４７】
また、本発明によれば、反射ミラー部を一対の支持部を中心にベースに対して揺動自在に構成し、ベースの反射ミラー部側に一対の固定電極を配置し、前記反射ミラー部の裏面にはミラー側櫛歯部を形成し、前記各固定電極の前記反射ミラー部側には、前記ミラー側櫛歯部に噛み合う電極側櫛歯部を形成し、前記各固定電極と前記反射ミラー部との間に電圧を印加して静電力で前記反射ミラー部が前記一対の支持部を揺動中心軸として揺動する光偏向器を設け、この光偏向器の前記反射ミラー部にレーザ光を照射し、この照射されたレーザ光の反射光の方向を前記反射ミラー部の揺動によって変化させて投影画像を得るように構成したので、走査周波数の高い画像を表示できる。
【００４８】
また、本発明によれば、前記表示装置において、前記反射ミラー部からの反射光は、光アドレス型空間光変調素子に照射することによって書き込み、この光アドレス型空間光変調素子に書き込んだ光情報を投影したので、光アドレス型空間変調素子を用いて走査周波数の高い画像を表示できる。
【図面の簡単な説明】
【図１】（Ａ）は本発明の第１実施形態に係る光偏向器の分解斜視図、（Ｂ）は同光偏向器の概略側面図である。
【図２】本発明の第１実施形態に係る光偏向器の斜視図である。
【図３】本発明の第１実施形態に係る光偏向器の概略側面図である。
【図４】本発明の第１実施形態を示す反射ミラー部の裏面側の斜視図である。
【図５】（Ａ）は本発明の櫛歯電極の場合における静電力を説明するための側面図、（Ｂ）は第１従来例の平行平面電極の場合における静電力を説明するための側面図である。
【図６】静電力の具体的大きさを説明するための反射ミラー部の斜視図である。
【図７】本発明の第２実施形態を示す反射ミラー部の裏面側の斜視図である。
【図８】本発明の第３実施形態を示す光偏光器の側面図である。
【図９】本発明の第３実施形態を示す光偏光器の側面図である。
【図１０】本発明の第４実施形態を示す光偏光器の側面図である。
【図１１】本発明の第４実施形態を示す光偏光器の側面図である。
【図１２】光偏向器を用いた表示装置の概略構成図である。
【図１３】光偏向器を用いた他の表示装置の概略構成図である。
【図１４】第１従来例の光偏向器の分解斜視図である。
【図１５】第１従来例の光偏光器の側面図である。
【図１６】第１従来例の光偏光器にあって反射ミラー部の厚みを薄くした場合の側面図である。
【図１７】第１従来例の光偏光器にあって反射ミラー部とベースとのギャップ間隔を広くした場合の側面図である。
【図１８】第２従来例の光偏向器の分解斜視図である。
【符号の説明】
１Ａ〜１Ｄ光偏光器
２ベース
７反射ミラー部
７ａ光反斜面
８支持部
９ミラー側櫛歯部
９ａ溝
９ｂ突起部
１０、１１固定電極
１２電極側櫛歯部
１２ａ溝
１２ｂ突起部
ＣＬ揺動中心軸[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical deflector that deflects light by reflecting light such as a laser beam, and a display device using the optical deflector.
[0002]
[Prior art]
Optical polarization for scanning devices for optical equipment such as electrophotographic copying machines, laser beam printers, barcode readers, optical deflection devices for optical disk tracking control devices, and display devices that scan laser light and project images. A vessel is being used.
[0003]
In general, optical deflectors that mechanically deflect light include rotary polygon mirrors and turbulent reflectors (galvano mirrors), but galvano mirror type is more than polygon mirror type. The mechanism can be reduced in size, and in recent semiconductor process technology, a prototype of a micromirror using a silicon substrate has been reported, and further reduction in size, weight, and cost can be expected.
[0004]
Conventional examples of such galvanomirror type optical deflectors are shown in FIGS. 14 to 17 and FIG. 18, respectively.
[0005]
FIG. 14 is an exploded perspective view of the first conventional optical deflector, and FIG. 15 is a schematic side view of the optical deflector. 14 and 15, the base 50 is provided with a pair of left and right standing portions 51 and 52, and a vibrating body 53 is disposed on the pair of standing portions 51 and 52. The vibrating body 53 includes an outer frame portion 54, a reflection mirror portion 55 disposed in the opening 54 a of the outer frame portion 54, and a position on the axis passing through the approximate center of gravity of the reflection mirror portion 55. A pair of support portions 56, 56 connecting the frame portion 54 are integrally formed. The left and right end portions of the outer frame portion 54 are fixed on the pair of standing portions 51 and 52, and the pair of support portions 56 and 56 support the reflection mirror portion 55 with respect to the outer frame portion 54, and this reflection. A torsion spring function for vibrating the mirror unit 55 is provided.
[0006]
A pair of left and right fixed electrodes 57, 58 are disposed on the base 50, and the pair of fixed electrodes 57, 58 are disposed at positions facing the left and right ends of the reflection mirror portion 55. A reflection mirror portion 55 is configured as an electrode on the other side of the pair of fixed electrodes 57, 58, and selectively interposed between the fixed electrodes 57, 58 and the reflection mirror portion 55 via the changeover switches SW1, SW2. It is comprised so that a voltage can be applied. Since the reflection mirror unit 55 is connected to the outer frame unit 54 via a pair of support units 56, 56, voltage application to the reflection mirror unit 55 may be applied to the outer frame unit 54.
[0007]
In the above configuration, when a voltage is applied between one fixed electrode 57 and the reflection mirror portion 55, the left side of the reflection mirror portion 55 is attracted by an electrostatic force, and the reflection mirror portion 55 causes the pair of support portions 56, 56 to move. It rotates counterclockwise as a swing center axis CL (shown in FIG. 15), and when a voltage is applied between the other fixed electrode 58 and the reflection mirror portion 55, the reflection mirror portion 55 is attracted by electrostatic force. Then, the right side of the reflection mirror portion 55 rotates in the clockwise direction with the pair of support portions 56 and 56 as the swing center axis CL (shown in FIG. 15). Accordingly, the reflection mirror unit 55 swings to the left and right by alternately turning on and off the changeover switches SW1 and SW2 and alternately applying a voltage to the pair of fixed electrodes 57 and 58. The reflection angle of the light applied to the reflection mirror unit 55 is changed by the swinging of the reflection mirror unit 55, and thereby the light is deflected.
[0008]
FIG. 18 is an exploded perspective view of a second conventional optical deflector. In FIG. 18, the auxiliary base member 60 is fixed on the base 50, and the reflection mirror portion 55 is disposed in the opening 60 a of the auxiliary base member 60. A pair of support portions 56, 56 connect the both sides on the axis passing through the approximate center of gravity of the reflection mirror portion 55 and the outer auxiliary base member 60. The reflection mirror portion 55 is configured to be swingable about the pair of support portions 56 and 56. Further, comb teeth 61 are formed at both outer ends of the reflection mirror 55, and a fixed electrode is provided at a position of the auxiliary base 60 facing the comb teeth 61 and at a position lower than that. 57 and 58 are fixed, respectively. A comb tooth portion 62 that meshes with the comb tooth portion 61 is formed on the reflecting mirror portion 55 side of the pair of fixed electrodes 57 and 58.
[0009]
In the above configuration, when a voltage is applied between one fixed electrode 57 and the reflection mirror portion 55, the left side of the reflection mirror portion 55 is attracted by an electrostatic force, and the reflection mirror portion 55 causes the pair of support portions 56, 56 to move. When the voltage is applied between the other fixed electrode 58 and the reflection mirror unit 55, the right side of the reflection mirror unit 55 is attracted by the electrostatic force, and the reflection mirror unit rotates. 55 rotates in the clockwise direction with the pair of support portions 56, 56 as the swing center axis. Accordingly, as in the first conventional example, the reflection mirror portion 55 swings left and right by alternately applying a voltage to the pair of fixed electrodes 57 and 58.
[0010]
[Problems to be solved by the invention]
However, the first and second conventional examples have the following problems.
[0011]
That is, in the first conventional example, it is desirable that the weight of the reflection mirror 55 is lighter in order to swing the reflection mirror 55 at a high speed. Here, as shown in FIG. 16, when the thickness t of the reflection mirror portion 55 is reduced in order to reduce the weight, inconvenience such as bending of the light reflecting surface occurs, and there is a problem in rigidity.
[0012]
Further, in order to increase the deflection angle (deflection angle) of the reflection mirror unit 55, it is necessary to set a large gap interval between the reflection mirror unit 55 and the fixed electrodes 57 and 58 as shown in FIG. However, since the electrostatic force is inversely proportional to the square of the gap, a very large voltage is required to obtain the necessary driving force.
[0013]
On the other hand, in the second conventional example, unlike the first conventional example, the deflection angle can be increased if the heights of the comb teeth portions 61 and 62 are set large, and the voltage decreases if the number of comb teeth is increased. A large driving force can be obtained. However, since the comb-tooth portions 61 are provided at both outer end portions of the reflection mirror portion 55, it is inevitable that the reflection mirror portion 55 is enlarged. When the size of the reflection mirror unit 55 is increased, the resonance frequency of the reflection mirror unit 55 is lowered, and thus the reflection mirror unit 55 cannot be swung at a high speed. In particular, in order to obtain a large deflection angle or to obtain a large driving force at a low voltage, the height of the comb teeth portions 61 and 62 is increased, or the number of comb teeth is increased. As a result, the resonance frequency is further lowered.
[0014]
Therefore, the present invention has been made to solve the above-mentioned problems, and can swing at a high speed and a wide deflection angle even under a low driving power, and also has a problem with the rigidity of the reflecting mirror section. It is an object of the present invention to provide an optical deflector that does not generate light and a display device using the same.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is characterized in that a reflecting mirror portion having a light reflecting surface on the surface, a pair of supporting portions that swingably support the reflecting mirror portion with respect to the base, A pair of fixed electrodes arranged on the reflection mirror part side, and a voltage is applied between each fixed electrode and the reflection mirror part, and the reflection mirror part swings the pair of support parts by electrostatic force. In the optical deflector that oscillates as a moving central axis, the reflection mirror portion includes a mirror side comb tooth portion having a groove and a protrusion extending in a direction orthogonal to the oscillating central axis on the back surface thereof, Each fixed electrode includes, on the reflection mirror part side, an electrode side comb tooth part having a protrusion and a groove that can mesh with the mirror side comb tooth part, and the mirror side comb tooth part and the electrode side comb tooth part are , The height of the protrusion relative to the groove is determined by the oscillation center axis It is that configured to become lower as the distance al.
[0016]
Another feature of the present invention is that the reflection mirror portion having a light reflection surface on the surface, a pair of support portions that swingably support the reflection mirror portion with respect to the base, and the reflection mirror portion side of the base are disposed. A pair of fixed electrodes, and a voltage is applied between each of the fixed electrodes and the reflection mirror portion to cause the reflection mirror portion to swing with the pair of support portions as a swing center axis by an electrostatic force. In the optical deflector, the reflection mirror portion has a mirror-side comb tooth portion having a groove and a protrusion extending in a direction orthogonal to the oscillation central axis on the back surface, and the oscillation center axis. And a rib portion that connects the support portions to each other via the projection portion, and each of the fixed electrodes has a projection portion and a groove that can mesh with the mirror-side comb tooth portion on the reflection mirror portion side. The electrode side comb-tooth part which has this is provided.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
1 to 4 show a first embodiment of the present invention. FIG. 1A is an exploded perspective view of an optical deflector 1A, FIG. 1B is a schematic side view of the optical deflector 1A, and FIG. 3 is a perspective view of the deflector 1A, FIG. 3 is a schematic side view of the optical deflector 1A, and FIG.
[0020]
1 to 4, the base 2 of the optical deflector 1 </ b> A has a flat rectangular shape, and an upright portion 3 is integrally formed on the entire outer peripheral end of the base 2. A vibrating body 5 is disposed on the top.
[0021]
The vibrating body 5 includes a rectangular outer frame portion 6, a reflection mirror portion 7 disposed in the opening 6 a of the outer frame portion 6, and an axial position passing through the approximate center of gravity of the reflection mirror portion 7. The reflecting mirror portion 7 and the outer frame portion 6 are integrally formed from a pair of support portions 8 and 8. The outer frame portion 6 is fixed on the standing portion 3, and the reflection mirror portion 7 is swingable with a pair of support portions 8 and 8 as a swing center axis CL (shown in FIGS. 1 and 3). It is configured. A light reflecting film is formed on the surface of the reflecting mirror unit 7 to form a light reflecting surface 7a.
[0022]
Further, as shown in detail in FIG. 4, a mirror side comb tooth portion 9 including a groove 9a extending in a direction perpendicular to the oscillation center axis CL and a projection portion 9b is integrally formed on the back surface of the reflection mirror portion 7. Has been. A pair of left and right fixed electrodes 10 and 11 are disposed at a position on the base 2 facing the mirror side comb tooth portion 9 of the reflection mirror portion 7, and a groove 12 a and An electrode-side comb tooth portion 12 including the protrusion portion 12b is integrally formed. The mirror-side comb-tooth portion 9 and the electrode-side comb-tooth portion 12 are arranged such that one groove 9a, 12a and the other protrusion 9b, 12b face each other, that is, mesh with each other. . A voltage can be selectively applied between the fixed electrodes 10 and 11 and the reflection mirror unit 7 via the changeover switches SW1 and SW2, and the changeover switches SW1 and SW2 are alternately turned on and off. It is configured to control and alternately apply a voltage to the pair of fixed electrodes 11 and 12.
[0023]
Further, the reflection mirror portion 7 is formed to be thin, and the height of the mirror side comb teeth portion 9 and the electrode side comb teeth 12, specifically the engagement between the grooves 9 a and 12 a and the projection portions 9 b and 12 b. The stroke is formed high so as to obtain a wide deflection angle. That is, the reflection mirror unit 7 is light in weight as a whole and is configured to have a high resonance frequency.
[0024]
In the above configuration, as shown in FIG. 1B, when a voltage is applied between one fixed electrode 10 and the reflection mirror unit 7, the left side of the reflection mirror unit 7 is attracted by an electrostatic force, and the reflection mirror unit 7 rotates counterclockwise about the pair of support portions 8 as the oscillation center axis CL, and when a voltage is applied between the other fixed electrode 11 and the reflection mirror portion 7 as shown in FIG. Then, the suction force of one fixed electrode 10 is released, and the pair of twisted support portions 8 attempt to return the reflection mirror portion 7 to the original position by the elastic restoring force, and the right side of the reflection mirror portion 7 is static. By being attracted by the electric power, the reflection mirror unit 7 rotates in the clockwise direction with the pair of support units 8 as the swing center axis CL. Therefore, when the changeover switches SW1 and SW2 are alternately turned on / off, the reflection mirror 7 swings left and right by alternately applying a voltage to the pair of fixed electrodes 10 and 11. The reflection angle of the light applied to the reflection mirror unit 7 is changed by the swinging of the reflection mirror unit 7, and thereby the light is deflected. Note that voltage application to the reflection mirror unit 7 is applied to the outer frame unit 6 to which the reflection mirror unit 7 is connected.
[0025]
Here, the driving force of the reflecting mirror unit 7 is obtained by an electrostatic force generated between the mirror side comb-teeth portion 9 and the electrode side comb-teeth portion 12, and the gap distance between the two is independent of the swing position. Since it is narrow and constant, a large driving force can be obtained with a low voltage. The magnitude of the driving force will be described in detail below.
[0026]
The heights of the mirror side comb teeth portion 9 and the electrode side comb teeth portion 12 are set to a height necessary for obtaining a desired deflection angle, and the reflection mirror portion 7 is lightweight and has a high resonance frequency. Since it is configured, it can be swung at a high speed and with a large deflection angle even under a low voltage. In particular, when the reflecting mirror unit 7 is vibrated at the resonance frequency, the reflecting mirror unit 7 vibrates at the maximum displacement, and thus a large rotational force can be obtained with low power.
[0027]
In addition, since the reflection mirror portion 7 functions as a rib for increasing the strength of the projection 9b of the mirror side comb tooth portion 9, there is no problem in rigidity such that the light reflection surface 7a is bent even if the thickness is reduced. . The reflection mirror portion 7 is provided with the mirror-side comb-tooth portion 9 on the back side thereof, and the entire surface of the reflection mirror portion 7 can be configured as the light reflection surface 7a. Therefore, the light reflection surface 7a is set to the minimum necessary size. In this respect, the weight can be reduced.
[0028]
Next, the magnitude of the electrostatic force in the case of the comb electrode of the present invention and the case of the planar electrode of the first conventional example will be compared. In general, the electrostatic force F generated when a voltage V is applied between the fixed electrode and the reflecting mirror part 7 which is a movable part has a gap interval g, a dielectric constant between gaps ε, and an electrode depth. When W and the electrode width are L, in the case of a comb-tooth electrode as shown in FIG. 5A, the electrostatic force acting on one comb-tooth surface is F = εV ² W / 2g. In the case of a parallel plane electrode as shown in FIG. 5B, F = εV ² WL / 2g ² .
[0029]
In the case of parallel plane electrodes, the electrostatic force increases with the square of the gap interval. However, in order to increase the deflection angle of the reflecting mirror unit 7, it is necessary to increase the gap interval. Therefore, it becomes difficult to obtain a large electrostatic force. On the other hand, in the case of the comb-teeth electrode, the reflection mirror portion 7 moves in parallel with the gap, so that the gap interval is constant. Therefore, since the gap interval can be made as small as possible, a large electrostatic force can be obtained. Furthermore, since the number n of comb teeth can be made plural, the electrostatic force is further 2n times the above formula.
[0030]
Next, both cases are compared by substituting specific numerical values. As shown in FIG. 6, when the size of the reflecting mirror unit 7 is 2 mm square, W = 1 mm and L = 2 mm in the above formula. Also, assuming that the deflection angle is ± 10 degrees, in the case of comb-tooth electrodes, if the number of comb teeth is 50 (40 μm pitch) for each electrode and the gap interval g is 2 μm, the static force acting on a set of comb teeth The electric power f becomes f = εV ² × 1/2 × (2 × 10 ⁻⁴ ) = 2.5 × 10 ² × εV ² . A set of comb teeth has two surfaces on which electrostatic force works, and since there are 50 comb teeth, the electrostatic force F as a whole is F = 2 × 50f = 2.5 × 10 ⁵ × εV ^2. It becomes.
[0031]
In the case of a parallel plane electrode, when the deflection angle is ± 10 degrees, the outermost end portion of the reflection mirror portion 7 is displaced by 176 μm, which is the gap interval g. Therefore, the electrostatic force F is F = εV ² × 1 × 2/2 × (176 × 10 ⁻⁴ ) ² = 3.2 × 10 ³ × εV ² .
[0032]
From the above, when the comb electrode is used, an electrostatic force of about 80 times can be obtained at the same voltage. Furthermore, in the case of a comb electrode, the number of comb teeth can be increased or the gap interval can be narrowed by the manufacturing method, and a larger electrostatic force can be obtained.
[0033]
FIG. 7 is a perspective view of the back side of the optical deflector 1B showing the second embodiment of the present invention. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals in the drawing, and the description thereof is omitted. Only different configurations will be described.
[0034]
That is, as shown in FIG. 7, adjacent to the back surface side of the reflecting mirror portion 7 and on the swinging central axis CL passing through the pair of support portions 8 and 8, without providing the groove 9a. Ribs 20 are formed to connect the protrusions 9b. Since this part is irrelevant to the action of the electrostatic force, an electrostatic force having the same magnitude as that of the first embodiment can be obtained, and the rib 20 further increases the strength of the reflecting mirror unit 7. Thus, the rigidity is further improved.
[0035]
8 and 9 show a third embodiment of the present invention, and FIGS. 8 and 9 are schematic side views of the optical deflector 1C, respectively. 8 and 9, the third embodiment is different from the first embodiment only in the configuration of the mirror side comb teeth portion 9 and the electrode side comb teeth portion 12, and the other configurations are the same. Therefore, only the configuration of the mirror-side comb-tooth portion 9 and the electrode-side comb-tooth portion 12 will be described, and other configurations will be denoted by the same reference numerals in the drawings, and description thereof will be omitted.
[0036]
That is, in this third embodiment, the length of the swing direction of the mirror side comb tooth portion 9 and the electrode side comb tooth portion 12 (the direction orthogonal to the swing center axis CL) is the swing direction of the reflection mirror portion 7. It is formed shorter than the length of. By doing in this way, since the angle until the free end (outer end part) of the reflective mirror part 7 collides with the fixed electrodes 10, 11 or the base 2 can be increased, the deflection angle can be increased. FIG. 9 shows a state in which a voltage is applied between one fixed electrode 10 and the reflection mirror unit 7, and it can be seen that the swing angle is larger than that in the case of FIG. 3 of the first embodiment.
[0037]
10 and 11 show a fourth embodiment of the present invention, and FIGS. 10 and 11 are schematic side views of the optical deflector 1D. 10 and 11, in this fourth embodiment, only the configuration of the mirror side comb tooth portion 9 and the electrode side comb tooth portion 12 is different from that of the first embodiment, and the other configurations are the same. Therefore, only the configuration of the mirror-side comb-tooth portion 9 and the electrode-side comb-tooth portion 12 will be described, and other configurations will be denoted by the same reference numerals in the drawings, and description thereof will be omitted.
[0038]
That is, in the fourth embodiment, the heights of the mirror-side comb-tooth portion 9 and the electrode-side comb-tooth portion 12 are formed so as to decrease as the distance from the oscillation center axis CL increases. By doing so, the angle until the free end (outer end) of the reflection mirror 7 collides with the fixed electrodes 10 and 11 even if the interval between the reflection mirror 7 and the fixed electrodes 10 and 11 is set narrow. Therefore, the deflection angle can be increased. FIG. 11 shows a state in which a voltage is applied between one fixed electrode 10 and the reflection mirror unit 7, and it can be seen that the swing angle is larger than that in the case of FIG. 3 of the first embodiment.
[0039]
As described above, according to the first to fourth embodiments, it is possible to swing at a wide deflection angle at a high speed even under a low voltage. However, the inside of each of the optical deflectors 1A to 1D is anodic bonded or the like. If this method is used for vacuum sealing, the influence of the air resistance can be eliminated with respect to the swinging of the reflecting mirror unit 7, and the swinging at a higher speed is preferable.
[0040]
FIG. 12 is a schematic configuration diagram of a display device using the optical deflectors 1A to 1D. In FIG. 12, the laser light emitted from the laser light source 30 is applied to the horizontal scanning optical deflector 31. In the horizontal scanning light deflector 31, the reflection mirror section is swung in synchronization with the horizontal frequency, and the reflected light is scanned in the horizontal direction by the swing. The laser beam reflected here is applied to the vertical scanning optical deflector 32. In the vertical scanning light deflector 32, the reflection mirror portion is swung in synchronization with the vertical frequency, and the reflected light is scanned in the vertical direction by the swing. The screen 33 is irradiated with the laser beam reflected here.
[0041]
Each of the optical deflectors 1A to 1D is used as the horizontal scanning optical deflector 31 and can be swung at a high speed and with a wide deflection angle as described above, so that it is synchronized with a scanning frequency of several tens of kHz. It can be swung. Of course, the optical deflectors 1A to 1D may be used for the vertical scanning optical deflector 32 as well.
[0042]
FIG. 13 is a schematic configuration diagram of another display device using the optical deflectors 1A to 1D. In FIG. 13, the laser light emitted from the laser light source 30 is applied to the horizontal scanning optical deflector 31. In the horizontal scanning light deflector 31, the reflection mirror section is swung in synchronization with the horizontal frequency, and the reflected light is scanned in the horizontal direction by the swing. The laser beam reflected here is applied to the vertical scanning optical deflector 32. In the vertical scanning light deflector 32, the reflection mirror portion is swung in synchronization with the vertical frequency, and the reflected light is scanned in the vertical direction by the swing. The laser beam reflected here passes through the focusing lens 34 and is applied to the optical address type spatial modulation element 35. The optical address type spatial modulation element 35 writes this optical information and amplifies the brightness, luminance, etc. on the surface side and displays it on the liquid crystal.
[0043]
On the other hand, the light from the lamp 36 is incident on the polarization beam splitter 40 through the infrared cut filter 37, the lens 38 and the wavelength filter 39, and the reflected light is irradiated on the optical address type spatial modulation element 35. The light reflected by the optical address type spatial modulation element 35 is again incident on the polarization beam splitter 40, and the light transmitted therethrough is irradiated on the screen 33 through the lens 41.
[0044]
Each of the optical deflectors 1A to 1D is used as the horizontal scanning optical deflector 31 and can be swung at a high speed and with a wide deflection angle as described above, so that it is synchronized with a scanning frequency of several tens of kHz. It can be swung. Of course, the optical deflectors 1A to 1D may be used for the vertical scanning optical deflector 32 as well.
[0045]
According to the embodiment, the display device is shown as an application example of the optical deflector. However, the scanning device for the optical device such as an electrophotographic copying machine, a laser beam printer, a barcode reader, and the optical disk tracking control device. Of course, the present invention can also be applied to other optical deflection devices.
[0046]
【The invention's effect】
As described above, according to the present invention, in the optical deflector in which the reflection mirror part is oscillated by an electrostatic force with the pair of support parts as the oscillating center axis, the back surface of the reflecting mirror part is arranged on the oscillating center axis. A mirror-side comb-tooth portion composed of a groove extending in an orthogonal direction and a projection portion is formed, and a groove and a projection portion engageable with the mirror-side comb-tooth portion are formed on the reflection mirror portion side of the pair of fixed electrodes. Since the electrode-side comb-tooth portion is formed, the mirror-side comb-tooth portion even if the height of the mirror-side comb-tooth portion and the electrode-side comb-tooth portion is set to a height necessary to obtain a desired deflection angle. The gap distance between the electrode side comb teeth portion does not change, and since the mirror side comb teeth portion is formed on the back surface side of the reflection mirror portion, the size of the reflection mirror portion is the minimum required for the light reflecting slope. What is necessary is just to form in a magnitude | size, and the projection part of a mirror side comb-tooth part functions as an intensity | strength rib. Because the rigidity can be maintained even if the thickness of the reflecting mirror part is reduced, the reflecting mirror part can be configured to be light and have a high resonance frequency, so that it swings at a high speed and with a large deflection angle even under a low voltage. In addition, there is no problem with the rigidity of the reflecting mirror portion.
[0047]
Further , according to the present invention, the reflection mirror part is configured to be swingable with respect to the base around the pair of support parts, and the pair of fixed electrodes are disposed on the reflection mirror part side of the base, A mirror-side comb-tooth portion is formed on the back surface, and an electrode-side comb-tooth portion that meshes with the mirror-side comb-tooth portion is formed on the reflection mirror portion side of each fixed electrode, and each fixed electrode and the reflection mirror An optical deflector is provided in which the reflection mirror unit swings about the pair of support portions as a swing center axis by applying a voltage between the pair of support portions and a laser beam on the reflection mirror unit of the optical deflector. Since the projected image is obtained by changing the direction of the reflected light of the irradiated laser light by swinging the reflecting mirror, an image with a high scanning frequency can be displayed.
[0048]
Further, according to the present invention, in the display device, reflected light from the reflecting mirror unit writes by irradiating the optically addressable spatial light modulator, the optical information written in the optically addressable spatial light modulator Therefore, an image with a high scanning frequency can be displayed using the optical address type spatial modulation element.
[Brief description of the drawings]
FIG. 1A is an exploded perspective view of an optical deflector according to a first embodiment of the present invention, and FIG. 1B is a schematic side view of the optical deflector.
FIG. 2 is a perspective view of an optical deflector according to the first embodiment of the present invention.
FIG. 3 is a schematic side view of the optical deflector according to the first embodiment of the present invention.
FIG. 4 is a perspective view of the back side of the reflecting mirror portion showing the first embodiment of the present invention.
5A is a side view for explaining the electrostatic force in the case of the comb electrode of the present invention, and FIG. 5B is a side view for explaining the electrostatic force in the case of the parallel plane electrode of the first conventional example. FIG.
FIG. 6 is a perspective view of a reflecting mirror portion for explaining a specific magnitude of electrostatic force.
FIG. 7 is a perspective view of the back side of a reflection mirror portion showing a second embodiment of the present invention.
FIG. 8 is a side view of an optical polarizer showing a third embodiment of the present invention.
FIG. 9 is a side view of an optical polarizer showing a third embodiment of the present invention.
FIG. 10 is a side view of an optical polarizer showing a fourth embodiment of the present invention.
FIG. 11 is a side view of an optical polarizer showing a fourth embodiment of the present invention.
FIG. 12 is a schematic configuration diagram of a display device using an optical deflector.
FIG. 13 is a schematic configuration diagram of another display device using an optical deflector.
FIG. 14 is an exploded perspective view of an optical deflector of a first conventional example.
FIG. 15 is a side view of a first conventional optical polarizer.
FIG. 16 is a side view of the optical polarizer of the first conventional example when the thickness of the reflection mirror portion is reduced.
FIG. 17 is a side view of the optical polarizer of the first conventional example when the gap interval between the reflection mirror portion and the base is widened.
FIG. 18 is an exploded perspective view of a second conventional optical deflector.
[Explanation of symbols]
1A to 1D Optical polarizer 2 Base 7 Reflective mirror portion 7a Opposite slope 8 Support portion 9 Mirror side comb tooth portion 9a Groove 9b Protrusion portion 10, 11 Fixed electrode 12 Electrode side comb tooth portion 12a Groove 12b Protrusion portion CL Oscillation center axis

Claims

A reflection mirror portion having a light reflection surface on the surface, a pair of support portions that swingably support the reflection mirror portion with respect to the base, and a pair of fixed electrodes disposed on the reflection mirror portion side of the base An optical deflector in which a voltage is applied between each of the fixed electrodes and the reflection mirror portion, and the reflection mirror portion swings with the pair of support portions as swing center axes by electrostatic force;
The reflection mirror portion includes a mirror side comb tooth portion having a groove and a protrusion extending on the back surface thereof in a direction orthogonal to the oscillation central axis,
Each of the fixed electrodes includes, on the reflection mirror part side, an electrode side comb tooth part having a protrusion and a groove that can mesh with the mirror side comb tooth part,
The mirror-side comb-teeth portion and the electrode-side comb-teeth portion are configured such that the height of the protrusion with respect to the groove decreases as the distance from the oscillation central axis increases. .

A reflection mirror portion having a light reflection surface on the surface, a pair of support portions that swingably support the reflection mirror portion with respect to the base, and a pair of fixed electrodes disposed on the reflection mirror portion side of the base An optical deflector in which a voltage is applied between each of the fixed electrodes and the reflection mirror portion, and the reflection mirror portion swings with the pair of support portions as swing center axes by electrostatic force;
The reflection mirror portion is formed on the rear surface thereof along a mirror side comb tooth portion having a groove and a protrusion extending in a direction orthogonal to the swing center axis, and along the swing center axis. A rib portion connecting the projecting portions with each other,
Each of the fixed electrodes is provided with an electrode-side comb-tooth portion having a protrusion and a groove that can mesh with the mirror-side comb-tooth portion on the reflection mirror portion side.

A reflection mirror portion having a light reflection surface on the surface, a pair of support portions that swingably support the reflection mirror portion with respect to the base, and a pair of fixed electrodes disposed on the reflection mirror portion side of the base An optical deflector in which a voltage is applied between each of the fixed electrodes and the reflection mirror portion, and the reflection mirror portion swings with the pair of support portions as swing center axes by electrostatic force;
The reflection mirror portion includes a mirror side comb tooth portion having a groove and a protrusion extending in a direction orthogonal to the oscillation central axis on the back surface, and the fixed electrodes are disposed on the reflection mirror portion side. The mirror-side comb-tooth portion and the electrode-side comb-tooth portion each have a projection-side and a groove-side electrode-side comb-tooth portion that can mesh with the mirror-side comb-tooth portion. A display device comprising an optical deflector configured to become lower as the distance from the swing central axis increases.

A reflection mirror portion having a light reflection surface on the surface, a pair of support portions that swingably support the reflection mirror portion with respect to the base, and a pair of fixed electrodes disposed on the reflection mirror portion side of the base In the optical deflector in which the reflection mirror unit swings about the pair of support portions as the swing center axis by an electrostatic force by applying a voltage between each fixed electrode and the reflection mirror unit. The mirror portion is formed on the back surface thereof along a mirror side comb tooth portion having a groove and a protrusion extending in a direction orthogonal to the swing center axis, and the support center portion. Ribs connected via the protrusions, and each fixed electrode has an electrode side comb tooth portion having a protrusion and a groove that can mesh with the mirror side comb tooth portion on the reflection mirror portion side. A display device comprising an optical deflector provided