JP4572426B2 - OPTICAL DEVICE, ITS DRIVING METHOD, AND IMAGING DEVICE - Google Patents

Description

【００９２】
対極５２の形成に際し、上述した導電性粒子と混合して用いるバインダーは、銀塩溶液に耐性を有するものであればよく、例えば、天然ゴム系、セルロース系、フェノール系、ウレタン系又はエポキシ系の樹脂を用いることができる。このバインダーと導電性粒子の混合比は、重量比で、約８０：２０〜約９９：１の範囲であるのが好ましく、約９０：１０〜約９９：１の範囲であるのがより好ましい。この混合比が８０：２０より少ないと、得られる膜の強度が弱くなり過ぎるおそれがあり、一方、混合比が９９：１より多いと、相対的に導電性粒子が少なくなり過ぎて、必要な導電性が得られなくなるおそれがある。
【００９３】
対極５２は、炭素材料を主とする導電性粒子と前記バインダーとからなっているのがよいが、対極５２の一部がこれらの混合物で形成されていてもよい。
【００９４】
前記導電性粒子とバインダーの混合物を構成する導電性粒子には、少なくとも１種炭素材料が含まれていることが好ましいが、他の成分、たとえば銀、銅、ニッケルなどの金属又はその合金、あるいは化合物が、夫々単独、或いは、混合状態で含まれていてよい。このなかでも特に銀粒子は、対極５２の電位を安定させる効果を有するために、好ましい。
【００９５】
前記のように、導電性粒子をバインダーに含有させたもので対極５２を構成すると、コストの低減をはじめ、透過率の向上、電極間の短絡防止を実現することができる。しかし、光学装置の駆動電圧に起因すると考えられるが、導電性粒子をバインダーに含有させた対極の構成では、駆動中に対極５４内に銀が取り込まれて銀板と異なる電位を示したり、対極５２が化学的に不安定になる（銀が析出し、対極５４の組成が変わる）ために、駆動制御が困難になることがある。
【００９６】
ところが、前記の銀粒子などを多極５２の一部として形成すれば、電極の電位が安定化するのである。
【００９７】
対極５２の電位が銀電極の電位よりも５０ｍＶ以上、正又は負に異なっている場合に、前記金属を銀とし、電極内に銀粒子を混合させると効果的である。対極５２が銀電位よりも｜５０ｍＶ｜以上異なっていると、銀の析出、溶解が生じ難くなるため、上記した銀成膜層の使用によって電極の電位を銀電極と同等若しくは銀の析出、溶解を生じ易い電位にすることができる。
【００９８】
この場合、前記銀粒子が、同粒子以外の導電性粒子と前記バインダーとからなる成分に対し、０．０１倍〜１００倍の重量比で添加されていることが、対極５２の電位の安定化と混合物の調製のし易さからみて望ましく、この添加量は更に０．０５〜１０倍とするのがよい。
【００９９】
具体的には、前記銀粒子が、同粒子以外の導電性粒子と前記バインダーとからなるペーストの固形分の０．０１倍〜１００倍（更には０．０５〜１０倍）の重量比で添加されるのがよい。
【０１００】
また前記導電性粒子の粒径は、数μｍ〜数１０μｍであるのが好ましく、粒径がこの範囲より小さ過ぎても大き過ぎても、導電性粒子をバインダー中に均一に分散させることが困難になり、その結果、膜の電気抵抗が高くなりすぎるおそれがある。
【０１０１】
対極５２の下地層として第３層を構成する集電体には、電子伝導性を有し、かつ電気化学的に安定な材料が用いられる。本発明に用いられる電解液に対して使用できる集電体材料の代表例としては、周期律表の４Ａ族、６Ａ族、８族および１Ｂ族から選ばれた少なくとも１種の金属材料及びこれらの合金、またはＩＴＯなどの金属酸化物を用いることができる。
【０１０２】
また、カーボンペーストなどの導電性粒子層を用いた対極においては、該導電性粒子層と前記集電体との密着性を上げるために、その間に高分子層を介在させてもよい。このような高分子層は、集電体から導電性粒子層への電荷移動を円滑に行なわせるために、導電性高分子で構成するのがよい。そのような導電性高分子層の形成には、キャスト法や蒸着法など種々の方法が用いられるが、中にも電気化学重合法が好ましい。
【０１０３】
電気化学重合法は、モノマー分子を含有する溶液中に被形成物を浸漬し、この被形成物に通電することによってモノマー分子を重合させ、被形成物の表面に導電性高分子膜を形成させる手法である。
【０１０４】
電気学重合法によって形成される導電性高分子の種類には、モノマーをアニリンとするポリアニリン、モノマーをピロールとするポリピロール、同じくモノマーをチオフェンとするポリチオフェンなどがある。
【０１０５】
また、アニリン、ピロール、チオフェンなどは化学修飾が容易であるため、種々の誘導体が存在し、それに伴い誘導体高分子が存在する。例えば、ポリアニリンでは、誘導体のＮ−アルキルアニリン、Ｎ，Ｎ−ジメチルアニリン、１−アミノピレン、σ−フェニレンジアミンなどの重合体、ポリピロールでは、誘導体のＮ−メチルピロールなどの重合体、ポリチオフェンでは、チオフェンの３および４位をアルキル基、アルコキシル基、アリル基などで置換したポリチオフェン誘導体がある。
【０１０６】
電気化学重合法による高分子の合成は、図７に示すような専用セル４６によって行うのがよい。重合を行うには、できれば空気中の酸素を取り除くために、絶縁蓋４５を介して不活性ガスを導入できるコック４４を備えたものがよい。通常、高分子を重合するものを正極４８として、負極４７に適切な電極材料を用いる。なお、同図において、電源４１に対し電流計４２が陽極側に直列に接続され、電圧計４３は並列に接続されている。
【０１０７】
不活性ガスを吹き込んで脱酸素した溶媒４９に、重合するモノマーを適切な濃度で溶存させ、両極間に適切な電圧をかけると、正極４８上に所望の重合体が生成される。
【０１０８】
例えば、アニリンを電気化学重合する場合には、塩酸、硫酸、過塩素酸、テトラフルオロホウ酸などの水溶液（ｐＨ＜２）に、アニリンを約０．２〜１ｍｏｌ／ｌ溶かし、ＩＴＯを正極として、銀を参照電極として、０．７〜１．０Ｖの定電位または定電流の通電により酸化を行うと、ＩＴＯ上にポリアニリンがフィルム上に生成する。
【０１０９】
また、ピロールを電気化学重合する場合には、例えばアセトニトリルを溶媒とし、ピロールの濃度が０．０５〜０．１ｍｏｌ／ｌとし、ＩＴＯを正極、白金を負極とし、両極間に約３．５Ｖの電圧をかけると、ＩＴＯ上にポリピロールが生成する。
【０１１０】
さらに、チオフェンを電気化学重合する場合には、溶媒はアセトニトリルの他に、ベンゾニトリル、テトラヒドロフラン、塩化メチレンなどがよく使われ、負極には白金、ニッケル、グラファイトなどが使用できる。正極にＩＴＯとして電圧をかけると、ＩＴＯ上にポリチオフェンが生成する。
【０１１１】
通常、電気化学重合を行うには、十分な電流値の通電を行うために、電解質を溶存させる。例えば、ポリアニリンの電気化学重合では、塩酸などを加えてｐＨ１程度の酸性とし、またポリピロールやポリチオフェンを電気化学重合させる場合には、本発明の光学装置の中で使用する電解液に含まれる臭化銀などの銀塩の他に、ヨウ化リチウムや過塩素酸リチウムといったリチウム塩などが電解質として用いられる。このような電気化学重合では、重合と同時に電解質のアニオンがドーパントとして取り込まれるため、導電性の高い重合体膜が得られる。
【０１１２】
電気化学重合を行う条件は、モノマーの種類や溶媒や駆動法により異なるが、良好な膜を得るために、例えば定電流のポリアニリンの重合の場合には、３ｍＡ／ｃｍ² 以下、より好ましくは０．５ｍＡ／ｃｍ² であるのが望ましい。
【０１１３】
電気化学重合では、場合により共重合が不可能であることも可能であることもある。例えばピロールとチオフェンの共重合は、二種のモノマーの酸化電位が異なるため不可能であるが、２，２’−チエニルピロールや２，５−ジ（２−チエニル）−ピロールなどの誘導体をモノマーとすれば、酸化電位が近くなるため、チオフェンとピロールが１：１あるいは２：１の交互共重合体を合成することが可能である。
【０１１４】
こうして対極部分に電気化学重合を行って第２層を形成し、さらにその上に導電性粒子を含む層を第１層として塗布または印刷すれば好ましい対極を得ることができる。
【０１１５】
この第１層の厚さは数μｍ〜数十μｍ、第２層の厚さは５０〜５００ｎｍ、第３層の厚さは１００〜４００ｎｍであるのがよい。第３層は、ガラス、繊維強化プラスチック（ＦＲＰ）等の絶縁基板（厚さは例えば１ｍｍ程度）上に設けられ、ＩＴＯ、銅、銀、金、白金、ＳＵＳ等からなっていてよい。
【０１１６】
このように、対極５２を導電性粒子とバインダーの混合物層、高分子層及び下地の集電体の層とで積層構造とすれば、従来のように銀板等の金属板で構成した場合に比し、銀粒子が浮遊することなく、安定した特性を有する光学装置を提供することができる。
【０１１７】
ところで、参照極を設けることは、作用電極及び対極の安定した制御を行うのに有効である。すなわち、参照電極は電解液中で作用電極、対極の電位を高精度に制御でき、また作用電極、対極との電位差が所定の範囲に保たれるようリミッタ等で外部電源を制御すれば、作用電極又は対極の過剰な分極を防止でき、光学装置の劣化を抑制することが可能である。
【０１１８】
この参照極としては、前記対極と同様の材料構成のものを使用することができる。すなわち、白金などの遷移金属やＩＴＯなどの酸化物といった集電体上に、炭素材料などの導電性粒子とバインダーの混合物を塗布又は印刷したもの、若しくは白金などの遷移金属やその表面上に電析金属（例えば、銀）を析出させたものなどが、参照極に使用することができる。但し、参照極では銀等の金属の析出・溶解反応を積極的に行なわせないため、例えば炭素材料とバインダーの混合物に担持させる銀等の金属の量は、対極よりも少なくてよい。
【０１１９】
また、参照極の集電体に用いる金属としては、対極５２に用いる前記金属等の他に、タンタル、ニオブなども使用することができる。タンタル及びニオブは、比抵抗が他のものと比較して大であり、対極では分極が大きくなるため使用しないが、参照極は電位の監視のため微小な電流しか流れず、参照極の電位はほとんど変化しないので、これらの金属も参照極の集電体として使用することができる。
【０１２０】
次に、銀塩溶液１としては、臭化銀、塩化銀、ヨウ化銀等のハロゲン化銀を水又は非水溶媒に溶解させた溶液を用いることができる。この時、非水溶媒としては、ジメチルスルホキシド（ＤＭＳＯ）、ジメチルホルムアミド（ＤＭＦ）、ジエチルホルムアミド（ＤＥＦ）、Ｎ，Ｎ−ジメチルアセトアミド（ＤＭＡＡ）、Ｎ−メチルプロピオン酸アミド（ＭＰＡ）、Ｎ−メチルピロリドン（ＭＰ）、プロピレンカーボネート（ＰＣ）、アセトニトリル（ＡＮ）、２−メトキシエタノール（ＭＥＯＨ）、２−エトキシエタノール（ＥＥＯＨ）等を用いることができる。
【０１２１】
また、銀塩溶液１中のハロゲン化銀の濃度は、０．０３〜２．０ｍｏｌ／ｌであるのが好ましく、０．０５〜２．０ｍｏｌ／ｌであるのがより好ましい。
【０１２２】
また、銀塩溶液１の導電性を上げるとともに、ハロゲン化銀の溶解のために、臭素その他のハロゲンを供給可能な支持塩（支持電解質）を添加するのが好ましい。例えば、ハロゲン化ナトリウム、ハロゲン化カリウム、ハロゲン化カルシウム、ハロゲン化四級アンモニウム塩等をこの目的に用い得る。このような支持塩は、ハロゲン化銀の１／２〜五倍程度の濃度範囲で添加させるのが好ましい。
【０１２３】
次に、上述した本発明に基づく光学装置７６（例えば図１４の如き電極パターンを有するもの）をＣＣＤ（Charge coupled device)カメラに組み込んだ実施の形態について、図２を参照しながら説明する。
【０１２４】
図２に示すＣＣＤカメラ７０において、一点鎖線で示す光軸に沿って、１群レンズ７１、２群レンズ（ズーム用）７２、３群レンズ７３、４群レンズ（フォーカス用）７４およびＣＣＤパッケージ７５が適宜の間隔をおいてこの順に配設されており、ＣＣＤパッケージ７５には赤外カットフィルタ７５ａ、液晶光学ローパスフィルタ系７５ｂ、ＣＣＤ撮像素子７５ｃが収納されている。２群レンズ７２と３群レンズ７３との間には、３群レンズ７３寄りに既述した本発明に基づく光学装置７６が光量調節（光量絞り）のために同じ光路上に取付けられている。
なおフォーカス用の４群レンズ７４は、リニアモータ７７により光路に沿って３群レンズ７３とＣＣＤパッケージ７５との間を移動可能に配設され、またズーム用の２群レンズ７２は、光路に沿って１群レンズ７１と光学装置７６との間を移動可能に配設されている。
【０１２５】
この実施の形態によると、２群レンズ７２と３群レンズ７３の間にセットされた本発明に基づく光学装置７６は、既述したように電界の印加によって光量を調節できるので、これまでの機械的な光量絞り機構と根本的に違って、絞りを駆動させる機械構成を必要としないため、システムが小型化でき、実質的に光路の有効範囲の大きさまで小型化できる。したがって、ＣＣＤカメラの小型化を達成することが可能である。また、パターン化された電極への印加電圧の大きさによって光量を適切に制御できるので、従来のような回折現象を防止し、撮像素子へ十分な光量を入射させ、像のぼやけをなくせる。
【０１２６】
次に、別の好ましい実施の形態について、比較の例と対比させながら説明する。
【０１２７】
図３に示す光学装置は、図１３で説明したのとほぼ同様の光学フィルター（電気化学的調光素子）に本発明を適用したものである。
【０１２８】
この実施の形態では、図示の如く、セルを構成する一対の透明電極（例えば、ガラス基板）４、５が一定の間隔を置いて配置され、各基板４、５の対向面に、各一対の作用電極２ａ、２ｂ、２ｃ、２ｄ、２ｅ及び３ａ、３ｂ、３ｃ、３ｄ、３ｅが夫々互いに対向して設けられている。基板４と５は、スペーサ６により所定間隔に保持され、その間に銀塩溶液１が封入されている。
【０１２９】
そして、そのセルの外部には、図示はしないが作用電極と対極の間に通電させるための駆動電源回路及び還元電流電源回路と、セルの電解液の温度を検知する温度センサと還元電流電源回路及び駆動電源回路を制御する制御回路が設けられている。
【０１３０】
さらにこの実施の形態では、作用電極２ａ〜２ｅ及び３ａ〜３ｅの外周部に対極１７ａと１７ｂ及び参照電極２７ａ、２７ｂが設けられている。これらの対極１７ａ、１７ｂは基板４、５上にＩＴＯ膜をスパッタ法により約２００ｎｍの厚さに成膜して集電体の層を形成したものである。なお、作用電極２ａ〜２ｅ及び３ａ〜３ｅ並びに対極１７ａ、１７ｂの平面形状は、図１４に示したものと実質的に同一である。
【０１３１】
この実施の形態における貼り合せセルの作用電極２ａ〜２ｅ及び３ａ〜３ｅと対極１７ａ、１７ｂは、図４乃至図６に示す製造工程により製造することができる。
【０１３２】
なお、作用電極及び対極とは別に、素子の駆動を制御するためにこれらの電極の電位を監視するための参照電極２７ａ、２７ｂを設けることも可能である。その場合の製造方法は、下記の対極の製造方法に準拠する。
【０１３３】
まず、（ａ）に示す基板３１上にインジウムと錫の元素組成比が約９（Ｉｎ：Ｓｎ＝９：１）の透明導電膜３３をスパッタリング法により、約２００ｎｍの厚さに成膜する。スパッタリングは、酸化錫を５重量％含むＩＴＯの多結晶体をターゲトとして行う。
【０１３４】
しかる後に、酸化錫の薄膜を、上記ＩＴＯ膜の上に、同じくスパッタリング法により、厚さ約５ｎｍに成膜し、透明導電膜３３を形成する。このときは酸化錫の多結晶体をターゲットとする。
【０１３５】
次に、上記透明導電膜の上にクロム膜３２を同じくスパッタリング法により、約２００ｎｍの厚さに形成する（（ｂ））。この基板上にレジスト３４をスピンコートにより塗布した（（ｃ））後に、マスクにより所望のパターンに露光／現像する（（ｄ））。
【０１３６】
しかる後にクロム層３２の一部にエッチングを施し、さらに透明電極膜３３の酸化錫の層をイオンミリング（プラズマ雰囲気中で基板に高周波バイアスを印加してイオンを衝突させ、その物理的な作用によりエッチングすること）によりエッチングし、塩酸と硝酸の混酸によりＩＴＯ膜のエッチングを施す（（ｅ））。
以降残ったレジストを剥離し、所望の平面形状の作用電極２Ａ及び対極１７Ａ、また必要に応じて参照電極２７Ａを形成する（（ｆ））。
【０１３７】
次に、再びレジスト３４を塗布し（（ｇ））、異なるマスクにより露光／幻想を行い（（ｈ））、再度クロムのエッチングを行い、作用電極２Ａ上には引き出し電極３５を形成し、対極１７Ａ及び参照極２７Ａからはクロムをすべて除去する（（ｉ））。
【０１３８】
レジスト３４を再度剥離した（（ｊ））後、二酸化珪素３６をスパッタリング法により成膜し、各電極の表面が全面覆われるようにする（（ｋ））。
【０１３９】
しかる後に、図３及び図１３には全部を記していないが、作用電極２Ａ以外の部分で光を透過させないために、遮光用にブラックレジスト３７をスピンコートで塗布する（（ｌ））。さらに別のフォトマスクにより露光／現像を行い、作用電極２Ａ、対極１７Ａ及び参照極２７Ａを露出させて所望の基板を得た（（ｍ））。
【０１４０】
そして電極部分でブラックレジストに覆われていない表面上の二酸化珪素を、フッ酸とフッ化アンモニウムの混合液によりエッチングし、電極部分のＩＴＯ表面を露出させる（（ｎ））。
【０１４１】
その後に、対極１７Ａ及び参照極２７Ａに、炭素材料とセルロース系のバインダーからなり、炭素重量と同重量の銀粉（粒系１〜３μｍ）を分散させたペーストのスクリーン印刷を施し、これらの電極を形成する（（ｏ））。
【０１４２】
以上の製造工程を経、所望のパターニングを施して得られた基板を用い、図３に示すように、作用電極２ａ〜２ｅ及び３ａ〜３ｅ並びに対極１７ａ、１７ｂを対向するように配置し、スペーサを介して貼り合せ、内部に銀塩溶液１を封入した上、駆動電源回路、還元電流電源回路、制御回路及び温度センサを取付けて、本発明の光学装置を得た。
【０１４３】
銀塩溶液１には、臭化銀５００ｍＭ、ヨウ化ナトリウム７５０ｍＭをジメチルスルホキシド（ＤＭＳＯ）／ジメチルアセトアミド（ＤＭＡｃ）＝５０／５０の混合溶媒に溶解させたものを使用した。
【０１４４】
図８乃至図１０に実施例及び比較例の平均透過率変化を示す。なお、図８は２２℃、図９は４０℃、図１０は６０℃の場合である。作用電極に銀を電析させ、しかる後に、所定の還元電流を通電した場合を実施例、通電しない場合を比較例とした。平均透過率の測定は、３６００秒（１時間）行った。
【０１４５】
図８では２２℃の結果を示しているが、比較例では、還元電流を通電しないため、電析させた銀が徐々に溶解し、その結果、透過率が上昇する。これに対して、実施例では、６μＡの還元電流を通電するため、溶解する銀を補うことができ、透過率の上昇は大幅に抑えられる。
【０１４６】
４０℃では、温度が高いため、電析させた銀の自然溶解も速く、透過率は約２０００秒で２０％から全透過（１００％）になるが、還元電流を通電させた実施例では、透過率は小さな変化に抑えられる。この場合、銀の自然溶解が速いため、還元電流も１０μＡとなり、２２℃のときよりも大きな電流を要する（図９）。
【０１４７】
さらに、６０℃になると、電析させた銀の自然溶解はいっそう速くなり、還元電流を通電しないとき（比較例）は、透過率は約１２００秒で２０％から全透過（１００％）になる。これに対して、還元電流を通電させたとき（実施例）は２２℃や４０℃の場合よりも大きいが、透過率の変化は小さく抑えられる。この時の還元電流は１８μＡとなった（図１０）。
【０１４８】
以上のように、還元電流を通電することによって、透過率の上昇は効果的に抑制されるが、その電流値は温度によって異なる。したがって、温度センサにより、液温を監視し、その温度に適した還元電流を通電するようにする。
【０１４９】
これらの結果から、実施例では、電析した銀の自然溶出に伴う透過率の上昇を小さくすることができ、優れた特性を有する光学装置を提供することが可能である。
【０１５０】
なお、この実施形態においては、次のようにして電界集中の問題を解決することができる。すなわち、前記対極１７ａ、１７ｂの形成にペースト状材料を抑制または塗布を利用すると、ペースト状材料の流動性及び表面張力により、対極の端縁部の角が丸められ、実質的に角の存在しない対極１７ａ、１７ｂが形成される。したがって、図１５で説明したような電界集中が緩和され、その結果、銀塩溶液１から析出した銀の粒子はより大きく形成されるようなことはない。すなわち、銀の粒子が銀塩溶液中に浮遊して作用電極消色時の透明度を低下させたり、電極間を短絡させるような現象は、未然に防止される。
【０１５１】
以上、本発明を好ましい実施の形態に従い説明したが、前述した実施の形態は、本発明の技術的思想に基づき種々に変形が可能である。
【０１５２】
例えば、図２に示した電極パターンは、同心円状に限らず、ストライプ状、格子状等種々に変更が可能である。また各分割電極毎に異なるセルを設けることもできる。
【０１５３】
また、本発明の光学装置は、前述した光透過型に限らず、反射型にも適用できるし、公知のほかのフィルター材（例えば、有機系のエレクトロクロミック材、液晶、エレクトロルミネッセンス材等）と組み合わせて用いることも可能である。
【０１５４】
更に、本発明の光学装置は、ＣＣＤの光学絞りをはじめ、各種光学系、例えば、電子写真複写機の光通信機器等の光量調節用としても広く適用が可能である。
更に、本発明の光学装置は、光学フィルター以外に、キャラクターやイメージを表示する各種の画像表示素子に適用することができる。
【０１５５】
【発明の効果】
本発明の光学装置及びその駆動方法においては、作用電極に所定の物質を電析させた後にこの電析金属の溶解分を補充するため通電を行うので、透過率の上昇等の光学物性の変化、すなわち遮蔽度の低下（又は反射率の低下）を効果的に抑制することができる。
【０１５６】
また、本発明の撮像装置によれば、電界の印加によって光量を調節できる上記光学装置を光量絞りに適用するため、これまでの機械的な光量絞りと異なって大がかりな機械構成を必要とせず、実質的に光路の有効範囲にまで小型化することが可能となり、しかも光量を印加電界の大きさで制御して回析を防止し、像のぼやけを効果的に防ぐことができる。
【図面の簡単な説明】
【図１】（Ａ）は本発明の実施の形態による、電気化学的調光タイプの光学装置の構成図、（Ｂ）及び（Ｃ）は同装置に用いる還元電流電源回路の例を示す構成図である。
【図２】本発明の実施の形態の光学装置をＣＣＤカメラの光絞りに適用した撮像装置の縦断面図である。
【図３】本発明の別の実施の形態による、光学装置の概略構成図である（電気系統は省く）。
【図４】同、光学装置の製造工程を示すフロー図である。
【図５】同、光学装置の製造工程（図４から続く）を示すフロー図である。
【図６】同、光学装置の製造工程（図５から続く）を示すフロー図である。
【図７】電気化学重合装置の概略構成図である。
【図８】液温が２２℃のときの、透明電極に銀を電析させた後の、実施例及び比較例の透過率変化を示す図である。
【図９】液温が４０℃のときの、透明電極に銀を電析させた後の、実施例及び比較例の透過率変化を示す図である。
【図１０】液温が６０℃のときの、透明電極に銀を電析させた後の、実施例及び比較例の透過率変化を示す図である。
【図１１】従来の同種光学装置を示すもので、（Ａ）は断面、（Ｂ）は作用原理図である。
【図１２】同、光学装置の斜視図である。
【図１３】従来の同種光学装置の他例を示す断面図である。
【図１４】同、平面図である。
【図１５】対極に銀板を用いた従来の光学装置における銀粒子の析出／成長／脱落現象を示す概念図である。
【符号の説明】
１、２１…銀塩溶液、
２ａ〜２ｅ、３ａ〜３ｅ、２２、２３、５４…作用電極、
４、５、２４、２５…透明基板、６、２６…スペーサ、
１７ａ、１７ｂ、５２…対極、２７ａ、２７ｂ…参照電極、４１…直流電源、
４６…セル、４７…陰極、４８…陽極、５０…駆動電源回路、
５１…還元電流電源回路、５３…温度センサ、５５…制御回路
７０…ＣＣＤカメラ、７１…１群レンズ、７２…２群レンズ、
７３…３群レンズ、７４…４群レンズ、７５…ＣＣＤパッケージ、
７６…電気化学的光学装置[0001]
[Field of the Invention]
The present invention relates to an optical device, a driving method thereof, and an imaging device, for example, a display device for performing numerical display, character display, XY matrix display, or the like, or light transmission in a visible light region (wavelength: 400 to 700 nm). The present invention relates to an optical device, a driving method thereof, and an imaging device that are preferably applied to an optical filter or the like that can control the rate or light reflectance.
[0002]
[Prior art]
Conventionally, an ECD (electrochromic display element) is applied to a voltage-driven display device such as a digital timepiece.
[0003]
This ECD is a non-light-emitting display element, and displays as reflected light or transmitted light as an electrochemical light control element, and thus has an advantage such as less eye fatigue even when observed for a long time.
[0004]
As the EC material, for example, as disclosed in JP-A-59-24879, an organic molecular piorogen molecule derivative is known, and an ECD using this is reversibly colored as a liquid ECD. / Can create a decolored state.
[0005]
However, ECD using EC materials such as viologen molecule derivatives is insufficient in terms of response speed and shielding degree. Moreover, the light quantity adjusting device is required to be able to control the light transmittance in the visible light region, but sufficient characteristics cannot be obtained with the EC material as described above.
[0006]
Under these circumstances, the present inventors have focused attention on a dimming element utilizing the precipitation / dissolution phenomenon of a metal salt as an optical device (electrochemical dimming element) that can be replaced with ECD. An electro-optical device using dissolution was studied. As a result, an optical device having characteristics superior to those of EC materials in response speed and shielding degree could be obtained.
[0007]
The electrolytic solution used in this optical device is a silver (complex) salt solution that does not absorb in the visible light region. The silver salt solution uses a reversible plating bath capable of depositing / dissolving silver by voltage drive control, that is, a RED (Reversible Electro-Deposition) material, and is colored by attaching silver to a transparent electrode ( For example, by the reflected light), this adhesion film can perform substantially uniform light shielding in the visible light region. Moreover, since it is a non-cyanide silver salt solution, there are no problems associated with the safety of the working environment and waste liquid treatment that are observed in conventional cyan plating.
[0008]
Thus, by using a reversible system for depositing / dissolving silver from a silver salt on a transparent electrode, that is, by using a RED (Reversible Electro-Deposition) material which is a reversible plating material, low consumption is achieved. An optical device such as an optical filter that is non-light-emitting and that is suitable for the visible light region can be provided.
[0009]
The cell structure of this type of optical device will be described below with reference to the drawings.
[0010]
First, in the optical device shown in FIGS. 11 and 12, a pair of transparent glass substrates 24 and 25 are arranged as a display window at regular intervals. As shown in FIG. 11A, working electrodes 22 and 23 made of ITO (indium tin oxide obtained by doping indium oxide with tin) are provided on the inner surfaces of the substrates 24 and 25 so as to face each other. The silver salt solution 21 is disposed between the working electrodes 22 and 23. A counter electrode 26 made of a silver plate is also provided around the entire circumference between the substrates 24 and 25 as a spacer.
[0011]
The silver salt solution 21 is obtained by, for example, dissolving silver bromide in dimethyl sulfoxide (DMSO).
[0012]
In such a configuration, when the counter electrode 26 is an anode, the working electrodes 22 and 23 are cathodes, and a DC driving voltage is applied between them for a predetermined time,
Ag⁺+ E^-→ Ag
The resulting redox reaction occurs in the silver salt on the cathode side, and the working electrodes 22 and 23 shift from a transparent state to a colored state by the Ag precipitate. FIG. 11B is a principle diagram showing the operation at this time.
[0013]
As described above, when Ag is deposited on the working electrodes 22 and 23, a specific color (for example, reflected light) due to the Ag deposit can be observed from the display window. The filter action by coloring, that is, the transmittance of visible light (or the shade of coloring) varies with the magnitude of voltage or the application time thereof. Therefore, by controlling them, this cell can function as a variable transmittance display element or an optical filter.
[0014]
On the other hand, when a DC voltage is applied in the opposite direction between the counter electrode 26 and the working electrodes 22 and 23 in this colored state, the working electrodes 22 and 23 where Ag is deposited are now on the anode side. And there
Ag → Ag⁺+ E^-
The following reaction occurs, and Ag deposited on the working electrodes 22 and 23 is dissolved in the silver salt solution 21. Thereby, the working electrodes 22 and 23 which have been colored return to the original transparent state.
[0015]
Next, FIGS. 13 and 14 show another example of the optical apparatus.
[0016]
In this example, as shown in the cross-sectional view of FIG. 13, a pair of transparent glass substrates 4 and 5 constituting the cell are arranged at regular intervals, and the inner surfaces of the substrates 4 and 5 are made of each pair of ITO. The working electrodes 2a, 2b, 2c, 2d, 2e and 3a, 3b, 3c, 3d, and 3e are provided to face each other. Counter electrodes 7a and 7b made of silver plates are provided on the outer peripheral portions of these working electrodes 2a to 2e and 3a to 3e, and the substrates 4 and 5 are held at a predetermined interval by a spacer 6 between which the silver salt solution 1 is provided. It is enclosed.
[0017]
As shown in the plan view of FIG. 14, the working electrodes 2a to 2e and 3a to 3e and the counter electrodes 7a and 7b are formed in a concentric pattern. The electrodes 2a and 3a, 2b and 3b, 2c and 3c, 2d and 3d, 2e and 3e, and 7a and 7b are connected to the drive power supplies 8a, 8b, 8c, 8d, 8e, and 8f, respectively, by wiring made of chrome fine wires or the like. They are connected via 9a, 9b, 9c, 9d, 9e, 9f.
[0018]
In such a configuration, the working electrodes 2a and 3a, 2b and 3b, 2c and 3c, 2d and 3d, 2e and 3e facing each other have predetermined potentials (V1, V2, V3, V4, and V5. V6 is a counter electrode). 7a and 7b), silver can be deposited from the silver salt solution 1 on each electrode serving as a cathode and colored. The filter action by coloring, that is, the transmittance of visible light (or the shade of coloring) varies with the magnitude of voltage or the application time thereof.
[0019]
Therefore, if V1 = V2 = V3 = V4 = V5, the cell can be uniformly colored over the entire area, and the degree of concentration can be changed uniformly according to the voltage or its application time. Can do. For example, if | V1 |> | V2 |> | V3 |> | V4 |> | V5 |, the coloring density decreases from the center to the periphery (in other words, the transmittance increases). . Conversely, if | V1 | <| V2 | <| V3 | <| V4 | <| V5 |, the transmittance decreases from the center to the periphery. Such a configuration is useful as an optical diaphragm for a CCD (Charge Coupled Device) such as a TV camera, and can sufficiently cope with an improvement in the degree of integration of the CCD.
[0020]
[Problems to be solved by the invention]
However, the conventional electrochemical optical apparatus as described above deposits a metal such as silver on the surface of the working electrode and then short-circuits the external circuit to leave it as it is. Since the deposited metal was dissolved again in the electrolytic solution and the deposited film became thin, a phenomenon occurred in which the transmittance increased. Also, after depositing (depositing) the metal, if the external circuit is left open and allowed to stand, the dissolution rate will be slightly slower, but the deposited metal will be dissolved again in the electrolyte. As a result, the transmittance gradually increased. When such a phenomenon occurs, for example, a CCD camera cannot perform stable light control, and a problem such as an image blurring occurs.
[0021]
On the other hand, a mechanical light amount diaphragm has been used to adjust the light amount of a CCD (Charge coupled device) camera. However, as the CCD camera is further downsized, the mechanical light amount diaphragm described above has a larger mechanical structure around it to drive it as the aperture area becomes smaller, which limits the downsizing of the entire system. was there. Further, as the miniaturization of the CCD has progressed, various problems have arisen, such as the image blurring due to the diffraction of light in the mechanical light quantity diaphragm.
[0022]
The present invention has been made in order to improve the above circumstances, and its purpose is to deposit a substance such as a metal in an electrochemical optical device utilizing the precipitation / dissolution phenomenon of the substance such as a metal for light control, An optical device improved so as to effectively suppress an increase in transmittance (or a decrease in reflectance) caused by re-dissolution of the electrodeposited material in the electrolytic solution, and to prevent problems such as blurring of the image; An object of the present invention is to provide an imaging apparatus that realizes downsizing of the system, prevention of blurring of an image, and the like by applying the driving method and the optical device to the light amount adjustment.
[0023]
[Means for Solving the Problems]
That is, the optical device of the present invention comprises a working electrode, a counter electrode, and an electrolytic solution disposed between these electrodes. In the optical device that performs electrochemical light control, a predetermined substance is applied to the working electrode. It is characterized by providing an energizing means for replenishing the dissolved portion of the electrodeposited material after electrodeposition.
[0024]
The driving method of the present invention is a method for driving an optical device that includes a working electrode, a counter electrode, and an electrolytic solution disposed between the electrodes, and performs electrochemical light control. It is characterized in that after the material is electrodeposited, energization is performed to replenish the dissolved portion of the electrodeposited material.
[0025]
The image pickup apparatus of the present invention is characterized in that the optical device is provided for adjusting the amount of light in the optical path.
[0026]
According to the optical device and the driving method thereof of the present invention, in the optical device that performs dimming electrochemically, after depositing a predetermined substance, for example, a metal such as silver, on the working electrode, the electrodeposited substance As a result, the thinning of the electrodeposited film due to dissolution is effectively suppressed, and changes in optical properties such as light transmittance are suppressed. Can achieve sufficient light shielding.
[0027]
Further, according to the imaging apparatus of the present invention, the optical device attached thereto can adjust the amount of light by applying electrolysis, so that it does not require a large-scale mechanical configuration unlike conventional mechanical light amount diaphragms. In addition, it is possible to reduce the size to the effective range of the optical path, and to control the amount of light by the magnitude of the applied electric field to prevent diffraction and effectively prevent image blurring.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, it is preferable that the power supply circuit that is energized to replenish the dissolved portion of the electrodeposited material is connected between the working electrode and the counter electrode.
[0029]
And it is preferable to provide the sensor which detects the temperature of the said electrolyte solution, and the control circuit which controls the electric current energized by the said electricity supply means or the applied voltage based on the temperature information.
[0030]
The working electrode used in the present invention is preferably a transparent or translucent electrode having a transmittance of 70% or more in the visible region, and the electrolytic solution is preferably a silver salt solution. Furthermore, the electrolytic solution used in the present invention is not limited to this silver salt solution.
[0031]
Hereinafter, the present invention will be described more specifically based on preferred embodiments.
[0032]
An optical device according to a preferred embodiment of the present invention includes a pair of transparent or semi-transparent substrates disposed to face each other, at least a pair of working electrodes disposed on opposite surfaces of these substrates, and in contact with the working electrodes. An electrolysis solution containing a silver salt arranged, a counter electrode arranged in contact with the electrolysis solution, and a sensor for detecting the temperature of the electrolysis solution; a power supply circuit for passing a reduction current to the working electrode; A control circuit for controlling a reduction current by the power supply circuit based on temperature information from the sensor and a drive power supply for connecting the working electrode and a counter electrode are provided.
[0033]
As an example, an optical device as shown in FIG. 1A can be given (a reference electrode is not shown).
[0034]
That is, in the optical device of the embodiment shown in FIG. 1A, the glass substrates 4 and 5 are arranged to face each other via the spacer 6 as a display window, and the working electrodes 54 made of ITO are formed on the inner surfaces of these glass substrates 4 and 5. And the counter electrode 52 are arranged to face each other. And between the glass substrates 4 and 5 and the spacer 6, the silver salt solution 1 is enclosed as electrolyte solution.
[0035]
Further, the counter electrode 52 and the working electrode 54 are connected to a drive power supply circuit 50. The drive power supply circuit 50 is disposed so as to be switchable with a reduction current power supply circuit 51 as shown by a broken line or a solid line. Is connected to the control circuit 55 and the temperature sensor 53. One end of the probe 53 a of the temperature sensor 53 passes through the spacer 6 and is in contact with the silver salt solution 1.
[0036]
In the configuration described above, the drive power supply circuit 50 and the reduction current power supply circuit 51 need to be capable of outputting a desired current based on temperature information from the temperature sensor 53. Resistance r as shown in 1 (B)₁, R₂, R_ThreeAre connected in parallel so that they can be switched to a current, or a variable resistor is connected to a power source as shown in FIG. 3C, but it is not necessary to limit to these.
[0037]
Moreover, as the control circuit 55, the circuit of a PID control apparatus can be mentioned, for example.
[0038]
Further, the temperature sensor 53 is required to have a function of transmitting temperature information of the electrolytic solution to the control circuit 55. Generally, a temperature sensor 53 can transmit a temperature change of the electrolytic solution to the control circuit 55 in the form of an electric signal, for example, a thermistor. preferable.
[0039]
As shown in the figure, the probe 53a of the temperature sensor 53 is preferably in contact with the electrolytic solution as shown in the drawing, but it is not particularly limited to this, although it is preferable to know the liquid temperature more accurately. For example, if the probe 53a has a problem such as corrosion resistance, the tip of the probe 53a may be fastened to a portion inside the apparatus near the electrolytic solution, for example, the spacer 6. Even if it does in this way, practically a problem does not arise.
[0040]
As a material for the probe 53a, generally stainless steel (SUS304) having good corrosion resistance is sufficient. However, if a higher degree of corrosion resistance is required due to special or special circumstances, a chemically stable material such as gold or platinum may be used instead of stainless steel. Alternatively, the surface of stainless steel or other metal material may be coated with the above-described noble metal or other material having high chemical stability.
[0041]
The temperature information of the electrolytic solution detected by the temperature detector 53 described above is transmitted to the control circuit 55. In this embodiment, the control circuit 55 can adjust the following two output currents based on the temperature information from the temperature sensor 53. That is, one is the output current of the drive power supply circuit 50 and the other is the output current of the reduction current power supply circuit 51.
[0042]
That is, when the optical device is driven, the output current value of the drive power supply circuit 50 is adjusted by the control circuit 55 based on the temperature information of the electrolyte from the temperature sensor 53, and thereby the amount of metal deposited on the working electrode 54. (Refer to FIG. 11B for the principle) to maintain the light shielding degree of the optical device at a desired value.
[0043]
Such an operation is similarly performed for the power supply circuit 51 that supplies the reduction current. In this case, the dissolved amount of the deposited metal can be supplemented by adjusting the reduction current to always maintain a constant amount of electrodeposition.
[0044]
In this regard, the working electrode on which the metal is electrodeposited at the time of driving, when the external circuit is short-circuited or opened as described above, the electrodeposited metal is dissolved again in the electrolyte and the deposited film becomes thin. The transmittance increases gradually.
[0045]
Therefore, in this embodiment, the drive power supply circuit 50 is switched to the reduction current power supply circuit 51. Based on the temperature information of the electrolyte sent from the temperature sensor 53, the control circuit 55 adjusts the output current of the reduction current power supply circuit 51 and supplies a reduction current to replenish the dissolved metal deposit (reduction current). Current flows in the direction). Various waveforms such as a constant current, a constant voltage, a unipolar pulse, and a bipolar pulse are used as the power source 51 for supplying a reduction current to replenish the deposited metal. Among them, a constant current power source is preferably used.
[0046]
The time required for all the deposited metal to spontaneously dissolve is often considerably longer (several minutes to several tens of minutes) than the control time (several seconds) of electrodeposition or dissolution of the metal by the drive power supply circuit 50. For example, when the power supply circuit 51 is a constant current source, the current value supplied to the reduction current power supply circuit 51 is considerably smaller than the current value supplied to the drive power supply circuit 50 (from a fraction of a few thousandths). Degree). However, for example, when the reduction current is energized with a pulse, a current may instantaneously flow more than the drive power supply, but this is not excluded in the present invention.
[0047]
The reduction current value for making the shielding degree of the optical device constant varies depending on the temperature of the electrolytic solution as described above. That is, since the dissolution rate of a metal such as silver increases as the temperature increases, a larger current value is required to replenish the electrodeposited material such as silver than when the temperature is low. Therefore, what is necessary is just to detect the temperature of electrolyte solution with the temperature sensor 53, and to energize the electric current value according to the temperature information.
[0048]
In order to drive the optical device, light is shielded by depositing dissolved metal in the electrolyte on the surface of the working electrode 54, and light is transmitted by dissolving the deposited metal.
[0049]
At this time, in order to deposit the metal on the working electrode 54, the working electrode 54 may be polarized to become a cathode, and a current may be passed in the reduction direction so that electrons are supplied from the power source.
[0050]
On the other hand, in order to dissolve the deposited metal on the surface of the working electrode 54, the working electrode 54 may be polarized so as to be an anode, and an electric current may be passed in the oxidation direction so as to send electrons to the power source.
[0051]
The reduction current value required to deposit the metal to a predetermined light shielding degree in a certain time varies depending on the temperature. That is, as the temperature rises, the deposition rate of the metal increases, so that the reduction current value for obtaining a predetermined light shielding degree for a certain time can be reduced. On the other hand, if the temperature is low, the metal deposition rate is slow, so that a large reduction current value is required to realize the light shielding degree under the same conditions. The same applies to the oxidation current value necessary for dissolving the deposited metal.
[0052]
This reduction current value or oxidation current value also varies depending on the type and quality of the transparent conductive film constituting the working electrode 54, the structure of the electrolytic solution, and the like. Therefore, it is important to control the current flexibly according to each case.
[0053]
Thus, according to this embodiment, it is possible to effectively suppress an increase in transmittance due to dissolution of the deposited metal after electrodeposition.
[0054]
In the above-described embodiment, the drive power supply circuit 50 and the reduction current power supply circuit 51 share the combination of the control circuit 55 and the temperature sensor 53. However, in the present invention, these combinations are used individually. Also good. That is, the effect of the present invention is not changed by adopting a method in which the drive power supply circuit 50 and the reduction current power supply circuit 51 are switched independently of each other instead of being switched over.
[0055]
Further, in the present invention, the reduction power supply circuit 51 may be omitted, and the drive power supply circuit 50 may have the function.
[0056]
In the formation of the transparent electrode used as the working electrode 54 in the optical device of the present invention, an oxide in which tin is doped with indium (referred to as ITO) or tin oxide is used.
[0057]
The constituent element ratio of indium and tin is arbitrary, but In / Sn is preferably 0 to 9, and more preferably 0 to 1.5.
[0058]
It is also possible to use a transparent electrode having a two-layer structure in which a tin oxide layer is formed as thin as 1 to 50 nm on ITO, for example. Since the surface of the transparent conductive film of this electrode is coated with tin oxide, the state of the metal film deposited on the electrode surface is similar to the metal electrodeposited on the thin film of tin oxide alone. Therefore, the coloring of the metal film is suppressed to be small, and excellent spectral characteristics can be obtained.
[0059]
In addition, when the tin oxide layer is formed very thin as described above, the resistance of the entire film can be kept small. Therefore, when the optical device is driven, the polarization of the transparent electrode can be kept small.
[0060]
In forming the various transparent electrodes, a metal or an oxide thereof is used as a target, and a thin film of the metal or an oxide thereof is formed by applying an AC voltage to the DC voltage or DC voltage under reduced pressure or normal pressure. Sputtering method, vapor deposition method in which a metal or its oxide is melted and vaporized to form a film, vaporizing a gas containing a desired metal, and applying a DC voltage or an AC voltage to a DC voltage to chemically activate it, Various vapor deposition methods such as chemical vapor deposition (CVD) for forming a film containing a desired metal on an object are preferably used.
[0061]
As a target used in the sputtering, a single crystal or polycrystal of a compound containing a film forming component element is used. The composition of the film formation can be controlled by the elemental composition ratio in the target. For example, in a polycrystal obtained by mixing tin oxide with ITO, the composition of the film can be controlled by changing the amount of tin oxide to be mixed.
[0062]
The target may be a target in which a small amount of a different element such as fluorine or antimony is mixed for reasons such as reducing the resistance value of the film.
[0063]
During film formation by sputtering, the temperature in the reaction vessel is adjusted appropriately. The critical temperature between the crystallinity and the amorphousness of the film during film formation depends on the In / Sn ratio in the film, so the temperature is adjusted to an appropriate temperature according to the desired In / Sn ratio. It is desirable to do.
[0064]
The sputtering method is performed while the inside of the reaction vessel is once evacuated and argon is mainly introduced into the vessel as an inert gas. Depending on the specifications of various physical properties such as the sheet resistance value of the film to be formed, a slight amount of oxygen may be mixed as required.
[0065]
In addition, if the transparent electrode is chemically or physically modified, the silver deposition potential on the transparent electrode can be lowered, the silver can be easily deposited, and damage to the transparent electrode and the solution itself can be reduced. .
[0066]
As a chemical modification method in this case, the surface treatment (chemical plating) of the transparent electrode is preferably performed by palladium or the like by a two-solution treatment method of a tin solution and a palladium solution. That is, as the surface activation treatment of the transparent electrode with palladium, the activity on the ITO electrode surface is enhanced by depositing palladium nuclei on the single substrate of the transparent conductive film.
[0067]
In this case, as the tin solution, tin chloride (SnCl₂) A solution prepared by dissolving 0.10 to 1.0 g in 1 l HCl at a concentration of 0.010 to 0.10%. As a palladium solution, palladium chloride (PdCl₂) A solution prepared by dissolving 0.10 to 1.0 g in 1 l HCl at a concentration of 0.010 to 0.10% can be used.
[0068]
In addition, as a physical modification method, a method of depositing a metal or the like nobler than silver on a transparent electrode can be employed.
[0069]
Next, the counter electrode 52 can be made of a metal different from the electrodeposited metal, and the electrodeposited metal can be deposited and dissolved thereon. For example, when an electrolytic solution containing a silver salt is used, it can be composed of a metal that has a smaller ionization tendency than silver, such as platinum, gold, and palladium, and silver can be electrodeposited thereon.
[0070]
Further, if the counter electrode 52 has a laminated structure, the first layer is made of platinum, palladium, or gold and silver is electrodeposited on the surface thereof, the potential of the electrode can be stabilized.
[0071]
That is, the use of a metal or metal oxide that exhibits a potential more noble than silver on the outermost surface of the counter electrode 52 and that facilitates the precipitation / dissolution reaction of silver is stable and the polarization of the counter electrode during driving (polarization) (Potential) can be kept small, and not only power consumption but also side reactions can be suppressed.
[0072]
However, a platinum group metal thin film such as platinum or palladium has low adhesion to an insulating substrate such as glass. Therefore, when the above metal is formed on an insulating substrate such as glass, a layer containing platinum or palladium is used as the first layer, and between this and the insulating substrate, titanium, chromium, which is a good conductor and has a film. It is preferable to interpose a metal such as tungsten or a metal oxide such as ITO or tin oxide as the second layer.
[0073]
That is, as a process, the first layer may be formed after the second layer is formed on the insulating substrate. In this case, depending on conditions, the second layer may become chemically unstable with respect to the electrolytic solution or may cause a side reaction with the electrolytic solution, so that the second layer is not in direct contact with the electrolytic solution. It is desirable to have a structure that covers the second layer.
[0074]
The first layer or the second layer can be formed by a vapor deposition method such as an evaporation method or a sputtering method, or a plating method.
[0075]
That is, the metal or metal oxide of the first layer or the second layer can be vapor-deposited by vaporizing the metal or metal oxide in a reduced pressure to form a film on a predetermined surface, or reduced in pressure or by using the metal or metal oxide as a target. A sputtering method for forming a desired metal or metal oxide film on a predetermined surface by applying a DC voltage to an AC voltage or an AC voltage under normal pressure is preferably used. The vapor deposition method includes a method of vaporizing a metal or metal oxide by resistance heating in a high vacuum, a method of vaporizing by irradiating a target metal or metal oxide with an electron beam (EB vapor deposition), and the like. Either method does not change the effect of the present invention.
[0076]
In the case where a film of platinum, palladium, or the like is formed on an insulating substrate such as silicon dioxide, the adhesion between the two is good, so that the second layer can be interposed arbitrarily.
[0077]
Further, formation of a metal layer such as platinum, palladium, or gold can be performed by a method other than the vapor phase film forming method. For example, these metals may be molded into a predetermined shape in advance, and the molded product may be embedded or fitted in a corresponding recess on the substrate surface. Such a method also has an advantage that it can be easily placed on the substrate because the molded product can be fixed to the recess using an adhesive as appropriate. However, as shown in FIG. 15, the corners of the counter electrode 52 on the transparent substrate 5 often have sharp corners in shape, so that electric field concentration occurs there, so that an inactive particle shape is formed on the counter electrode 52. The silver A tends to precipitate. Since the inactive silver particles A float in the silver salt solution 63, the transparency of the optical device may be lowered, or the electrodes may be short-circuited. Therefore, a vapor phase film forming method is usually used for forming the metal layer.
[0078]
Since platinum, palladium, and gold are noble metals than silver, the natural potential generated when immersed is higher than that of silver. For example, the standard electrode potential in an aqueous solution at 25 ° C. is 1.188 V for platinum, 0.915 V for palladium, and 1.50 V for gold. Since the standard electrode potential of silver is 0.7991V (see Chemical Handbook), platinum shows a noble potential of 0.389V with respect to silver, palladium has a noble potential of 0.116V, and gold has a noble potential of 0.70V. Will show. In addition, even in a non-aqueous solvent having a dimethyl sulfoxide (DMSO) / acetonitrile (AN) = 55/45 mixing ratio, it was confirmed that the relative potential of platinum or palladium with respect to silver shows a noble potential close to that in an aqueous solution. it can.
[0079]
Even if these metals are used as they are as the counter electrode 52, there is no problem in demonstrating the performance of the optical device. It is preferable to form a layer of a different base metal element. For example, when a silver salt solution is used, if a silver layer is formed on platinum or palladium, the potential shown when this electrode is immersed in the solution can be almost the same as that of silver. A counter electrode having excellent reversibility in the precipitation / dissolution reaction can be obtained.
[0080]
The layer of the dissimilar metal element can be formed by the above-described vapor deposition method or electrolytic plating, and the characteristics as a counter electrode are not changed by any method.
[0081]
Moreover, the counter electrode 52 can also be comprised with the mixture layer containing electroconductive particle. The conductive particles are made of at least one carbon material, and the binder for binding the conductive particles is selected from the group consisting of natural rubber, cellulose, phenol, urethane, and epoxy. It is preferable that it is made of at least one resin material.
[0082]
Examples of the carbon material used for the conductive particles include graphite (graphite), graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon black, activated carbon, and the like.
[0083]
Note that graphitizable carbon is a carbon material that is graphitized when heat-treated at about 2800 to 3000 ° C., and non-graphitizable carbon is a carbon material that is not graphitized even when heat-treated at about 3000 ° C.
[0084]
Graphitizable carbon, for example, is fired in a nitrogen stream under conditions of a temperature rise rate of 1 to 20 ° C. per minute, an ultimate temperature of 900 to 1300 ° C., and a retention time of about 0 to 5 hours at the ultimate temperature. Is generated. Pitch is produced by distillation using high-temperature pyrolysis of coal tar, ethylene bottom oil, crude oil, etc., asphalt, etc. (vacuum distillation, atmospheric distillation, steam distillation, etc.), thermal polycondensation, extraction, chemical polycondensation, etc. The pitch obtained by the operation or the pitch generated during the dry distillation of wood.
[0085]
In addition, this graphitizable carbon is obtained by carbonizing a polymer compound raw material such as polyvinyl chloride resin, polyvinyl acetate, polyvinyl butyrate, 3,5-dimethylphenol resin at 300 to 700 ° C. in a nitrogen stream, Even if baked under the same conditions as above, it is produced.
[0086]
Further, this graphitizable carbon is a condensed polycyclic hydrocarbon compound such as naphthalene, phenanthrene, anthracene, triphenylene, pyrene, perylene, pentaphen, pentacene, and derivatives thereof (for example, carboxylic acids, carboxylic anhydrides, carboxylic acids thereof). Imide, etc.), and mixtures of the above compounds, acenaphthylene, indole, isoindole, quinoline, isoquinoline, quinoxaline, phthalazine, carbazole, acridine, phenazine, phenanthridine, and the like, and their derivatives as described above It is also produced by carbonizing and baking.
[0087]
On the other hand, non-graphitizable carbon is produced, for example, by carbonizing and firing a furan resin made of furfuryl alcohol or furfural homopolymer or copolymer under the same conditions as those for graphitizable carbon.
[0088]
This non-graphitizable carbon is also generated from an organic material in which a functional group containing oxygen is introduced into a petroleum pitch having a specific H / C atomic ratio (for example, 0.6 to 0.8) (so-called oxygen crosslinking). The For example, non-graphitizable carbon materials include phenol resin, acrylic resin, halogenated vinyl resin, polyimide resin, polyamideimide resin, polyamide resin, conjugated resin, cellulose having an H / C atomic ratio of 0.6 to 0.8. Organic polymer compounds such as derivatives thereof, condensed polycyclic hydrocarbon compounds such as naphthalene, phenanthrene, anthracene, triphenylene, pyrene, perylene, pentaphen, pentacene, and derivatives thereof (for example, carboxylic acids, carboxylic anhydrides, Carboxylic acid imides, etc.), and various condensed heterocyclic rings such as various pitches, acenaphthylene, indole, isoindole, quinoline, isoquinoline, quinoxaline, phthalazine, carbazole, acridine, phenazine, phenanthridine, etc., mainly composed of a mixture of the above-mentioned compounds Compound and its inducement The body is produced by carbonizing and firing under the same conditions as described above.
[0089]
The graphitizable carbon and non-graphitizable carbon described above can also be produced by adding a phosphorus compound to the starting material or precursor and then performing carbonization and firing in the same manner as described above.
[0090]
Further, when the conductive particles used for forming the counter electrode 52 are composed of graphite, in addition to natural graphite, for example, artificial graphite obtained by heat-treating graphitized carbon as a precursor at a high temperature of 2000 ° C. or higher. Can be used.
[0091]
The table below compares the characteristics of graphite, soft carbon, hard carbon and activated carbon.

[0092]
In forming the counter electrode 52, the binder used by mixing with the above-described conductive particles may be any one having resistance to the silver salt solution. For example, natural rubber, cellulose, phenol, urethane, or epoxy may be used. Resin can be used. The mixing ratio of the binder and the conductive particles is preferably in the range of about 80:20 to about 99: 1 by weight, and more preferably in the range of about 90:10 to about 99: 1. If the mixing ratio is less than 80:20, the strength of the resulting film may be too weak. On the other hand, if the mixing ratio is more than 99: 1, the number of conductive particles is relatively reduced, which is necessary. There is a possibility that conductivity cannot be obtained.
[0093]
The counter electrode 52 is preferably composed of conductive particles mainly composed of a carbon material and the binder, but a part of the counter electrode 52 may be formed of a mixture thereof.
[0094]
The conductive particles constituting the mixture of the conductive particles and the binder preferably contain at least one kind of carbon material, but other components such as metals such as silver, copper and nickel or alloys thereof, or Each compound may be contained alone or in a mixed state. Among these, silver particles are particularly preferable because they have an effect of stabilizing the potential of the counter electrode 52.
[0095]
As described above, when the counter electrode 52 is composed of conductive particles contained in a binder, it is possible to realize cost reduction, improvement of transmittance, and prevention of short circuit between electrodes. However, although it is considered to be due to the driving voltage of the optical device, in the configuration of the counter electrode in which conductive particles are contained in the binder, silver is taken into the counter electrode 54 during driving and exhibits a potential different from that of the silver plate. Since 52 is chemically unstable (silver is deposited and the composition of the counter electrode 54 is changed), drive control may be difficult.
[0096]
However, if the silver particles or the like are formed as part of the multipole 52, the potential of the electrode is stabilized.
[0097]
When the potential of the counter electrode 52 is 50 mV or more different from the potential of the silver electrode, positive or negative, it is effective to mix the metal with silver and mix silver particles in the electrode. When the counter electrode 52 is different from the silver potential by | 50 mV | or more, silver deposition and dissolution are difficult to occur. Therefore, by using the above-described silver film formation layer, the electrode potential is equal to the silver electrode or silver deposition and dissolution. It is possible to make the potential easy to generate.
[0098]
In this case, the potential of the counter electrode 52 is stabilized because the silver particles are added in a weight ratio of 0.01 to 100 times with respect to a component composed of conductive particles other than the particles and the binder. In view of the ease of preparation of the mixture, it is desirable, and this addition amount is further preferably 0.05 to 10 times.
[0099]
Specifically, the silver particles are added at a weight ratio of 0.01 to 100 times (more preferably 0.05 to 10 times) the solid content of the paste composed of conductive particles other than the particles and the binder. It is good to be done.
[0100]
The conductive particles preferably have a particle size of several μm to several tens of μm. If the particle size is too small or too large, it is difficult to uniformly disperse the conductive particles in the binder. As a result, the electrical resistance of the film may be too high.
[0101]
For the current collector constituting the third layer as the base layer of the counter electrode 52, a material having electron conductivity and electrochemically stable is used. Representative examples of current collector materials that can be used for the electrolytic solution used in the present invention include at least one metal material selected from Group 4A, Group 6A, Group 8 and Group 1B of the periodic table, and these An alloy or a metal oxide such as ITO can be used.
[0102]
In the counter electrode using a conductive particle layer such as a carbon paste, a polymer layer may be interposed between the conductive particle layer and the current collector in order to improve the adhesion. Such a polymer layer is preferably composed of a conductive polymer in order to smoothly perform charge transfer from the current collector to the conductive particle layer. Various methods such as a casting method and a vapor deposition method are used for the formation of such a conductive polymer layer, and an electrochemical polymerization method is preferable among them.
[0103]
In the electrochemical polymerization method, an object is immersed in a solution containing monomer molecules, and the monomer molecules are polymerized by energizing the object to form a conductive polymer film on the surface of the object. It is a technique.
[0104]
Examples of the conductive polymer formed by the electropolymerization method include polyaniline whose monomer is aniline, polypyrrole whose monomer is pyrrole, and polythiophene whose monomer is thiophene.
[0105]
In addition, aniline, pyrrole, thiophene, and the like are easily chemically modified, and therefore various derivatives exist, and accordingly, derivative polymers exist. For example, polyaniline is a derivative N-alkylaniline, N, N-dimethylaniline, 1-aminopyrene, σ-phenylenediamine and other polymers, polypyrrole is a derivative N-methylpyrrole and other polymers, and polythiophene is thiophene. There are polythiophene derivatives in which the 3 and 4 positions are substituted with an alkyl group, an alkoxyl group, an allyl group or the like.
[0106]
The synthesis of the polymer by the electrochemical polymerization method is preferably performed by a dedicated cell 46 as shown in FIG. In order to carry out the polymerization, it is preferable to provide a cock 44 capable of introducing an inert gas through an insulating lid 45 in order to remove oxygen in the air. Usually, an electrode material suitable for the negative electrode 47 is used as a positive electrode 48 that polymerizes a polymer. In the figure, an ammeter 42 is connected in series to the anode side with respect to the power source 41, and a voltmeter 43 is connected in parallel.
[0107]
When a monomer to be polymerized is dissolved in an appropriate concentration in a solvent 49 that has been deoxygenated by blowing an inert gas and an appropriate voltage is applied between the two electrodes, a desired polymer is produced on the positive electrode 48.
[0108]
For example, when electrochemically polymerizing aniline, aniline is dissolved in an aqueous solution (pH <2) such as hydrochloric acid, sulfuric acid, perchloric acid, and tetrafluoroboric acid, and ITO is used as a positive electrode. When silver is used as a reference electrode and oxidation is performed by applying a constant potential or a constant current of 0.7 to 1.0 V, polyaniline is formed on the ITO film.
[0109]
In the case of electrochemical polymerization of pyrrole, for example, acetonitrile is used as a solvent, the concentration of pyrrole is 0.05 to 0.1 mol / l, ITO is used as a positive electrode, platinum is used as a negative electrode, and about 3.5 V between both electrodes. When voltage is applied, polypyrrole is formed on the ITO.
[0110]
Furthermore, when electrochemically polymerizing thiophene, benzonitrile, tetrahydrofuran, methylene chloride and the like are often used in addition to acetonitrile, and platinum, nickel, graphite and the like can be used for the negative electrode. When a voltage is applied to the positive electrode as ITO, polythiophene is generated on the ITO.
[0111]
Usually, in order to perform electrochemical polymerization, an electrolyte is dissolved in order to energize with a sufficient current value. For example, in the electrochemical polymerization of polyaniline, hydrochloric acid or the like is added to make it acidic to about pH 1, and when polypyrrole or polythiophene is electrochemically polymerized, the bromide contained in the electrolytic solution used in the optical apparatus of the present invention is used. In addition to silver salts such as silver, lithium salts such as lithium iodide and lithium perchlorate are used as the electrolyte. In such electrochemical polymerization, an anion of the electrolyte is taken in as a dopant simultaneously with the polymerization, so that a highly conductive polymer film can be obtained.
[0112]
The conditions for electrochemical polymerization vary depending on the type of monomer, solvent and driving method, but in order to obtain a good film, for example, in the case of polymerization of polyaniline with a constant current, 3 mA / cm.²Or less, more preferably 0.5 mA / cm²It is desirable that
[0113]
In electrochemical polymerization, in some cases, copolymerization may or may not be possible. For example, copolymerization of pyrrole and thiophene is impossible because the oxidation potentials of the two types of monomers are different, but derivatives such as 2,2′-thienylpyrrole and 2,5-di (2-thienyl) -pyrrole are monomers. Then, since the oxidation potential is close, it is possible to synthesize an alternating copolymer of 1: 1 or 2: 1 of thiophene and pyrrole.
[0114]
In this way, a preferred counter electrode can be obtained by performing electrochemical polymerization on the counter electrode portion to form the second layer, and further applying or printing a layer containing conductive particles thereon as the first layer.
[0115]
It is preferable that the thickness of the first layer is several μm to several tens of μm, the thickness of the second layer is 50 to 500 nm, and the thickness of the third layer is 100 to 400 nm. The third layer is provided on an insulating substrate (thickness is about 1 mm, for example) such as glass or fiber reinforced plastic (FRP), and may be made of ITO, copper, silver, gold, platinum, SUS, or the like.
[0116]
In this way, when the counter electrode 52 has a laminated structure of a mixture layer of conductive particles and a binder, a polymer layer, and an underlayer current collector layer, when the counter electrode 52 is formed of a metal plate such as a silver plate as in the past, In contrast, an optical device having stable characteristics can be provided without silver particles floating.
[0117]
By the way, providing the reference electrode is effective for stable control of the working electrode and the counter electrode. In other words, the reference electrode can control the potential of the working electrode and the counter electrode with high accuracy in the electrolytic solution, and if the external power source is controlled with a limiter or the like so that the potential difference between the working electrode and the counter electrode is maintained within a predetermined range, Excessive polarization of the electrode or the counter electrode can be prevented, and deterioration of the optical device can be suppressed.
[0118]
As this reference electrode, a material having the same material structure as that of the counter electrode can be used. In other words, a current collector such as a transition metal such as platinum or an oxide such as ITO is coated or printed with a mixture of conductive particles such as a carbon material and a binder, or a transition metal such as platinum or a current on the surface thereof. An electrodeposited metal (for example, silver) can be used for the reference electrode. However, since the reference electrode does not actively precipitate and dissolve the metal such as silver, the amount of metal such as silver supported on the mixture of the carbon material and the binder may be smaller than that of the counter electrode.
[0119]
In addition to the metal used for the counter electrode 52, tantalum, niobium, or the like can be used as the metal used for the current collector of the reference electrode. Tantalum and niobium are not used because the specific resistance is large compared to others and the polarization is large at the counter electrode, but the reference electrode only uses a very small current for potential monitoring, and the potential of the reference electrode is Since these metals hardly change, these metals can also be used as a current collector for the reference electrode.
[0120]
Next, as the silver salt solution 1, a solution in which silver halide such as silver bromide, silver chloride, silver iodide or the like is dissolved in water or a non-aqueous solvent can be used. At this time, non-aqueous solvents include dimethyl sulfoxide (DMSO), dimethylformamide (DMF), diethylformamide (DEF), N, N-dimethylacetamide (DMAA), N-methylpropionic acid amide (MPA), N-methyl. Pyrrolidone (MP), propylene carbonate (PC), acetonitrile (AN), 2-methoxyethanol (MEOH), 2-ethoxyethanol (EEOH) and the like can be used.
[0121]
Moreover, it is preferable that it is 0.03-2.0 mol / l, and, as for the density | concentration of the silver halide in the silver salt solution 1, it is more preferable that it is 0.05-2.0 mol / l.
[0122]
Further, it is preferable to add a supporting salt (supporting electrolyte) capable of supplying bromine or other halogens in order to increase the conductivity of the silver salt solution 1 and dissolve silver halide. For example, sodium halide, potassium halide, calcium halide, halogenated quaternary ammonium salt and the like can be used for this purpose. Such a supporting salt is preferably added in a concentration range of about 1/2 to 5 times that of silver halide.
[0123]
Next, an embodiment in which the above-described optical device 76 according to the present invention (for example, one having an electrode pattern as shown in FIG. 14) is incorporated in a CCD (Charge coupled device) camera will be described with reference to FIG.
[0124]
In the CCD camera 70 shown in FIG. 2, a first group lens 71, a second group lens (for zooming) 72, a third group lens 73, a fourth group lens (for focusing) 74, and a CCD package 75 along the optical axis indicated by the alternate long and short dash line. Are arranged in this order at appropriate intervals, and an infrared cut filter 75a, a liquid crystal optical low-pass filter system 75b, and a CCD image sensor 75c are accommodated in the CCD package 75. Between the second group lens 72 and the third group lens 73, the optical device 76 according to the present invention described above near the third group lens 73 is mounted on the same optical path for light amount adjustment (light amount diaphragm).
The focusing fourth group lens 74 is arranged to be movable between the third group lens 73 and the CCD package 75 along the optical path by a linear motor 77, and the zoom second group lens 72 is arranged along the optical path. The first group lens 71 and the optical device 76 are movably disposed.
[0125]
According to this embodiment, the optical device 76 according to the present invention set between the second group lens 72 and the third group lens 73 can adjust the amount of light by applying an electric field as described above. Unlike a typical light quantity diaphragm mechanism, since a mechanical configuration for driving the diaphragm is not required, the system can be miniaturized, and the size can be substantially reduced to the size of the effective range of the optical path. Therefore, it is possible to reduce the size of the CCD camera. In addition, since the amount of light can be appropriately controlled according to the magnitude of the voltage applied to the patterned electrodes, the conventional diffraction phenomenon can be prevented, and a sufficient amount of light can be incident on the image sensor to eliminate image blurring.
[0126]
Next, another preferred embodiment will be described in comparison with a comparative example.
[0127]
The optical device shown in FIG. 3 is obtained by applying the present invention to an optical filter (electrochemical light control device) that is almost the same as that described in FIG.
[0128]
In this embodiment, as shown in the figure, a pair of transparent electrodes (for example, glass substrates) 4 and 5 constituting a cell are arranged at a predetermined interval, and each pair of transparent electrodes 4 and 5 is disposed on the opposing surface of each substrate 4 and 5. The working electrodes 2a, 2b, 2c, 2d, 2e and 3a, 3b, 3c, 3d, 3e are provided opposite to each other. The substrates 4 and 5 are held at a predetermined interval by the spacer 6, and the silver salt solution 1 is enclosed therebetween.
[0129]
And outside the cell, although not shown, a drive power supply circuit and a reduction current power supply circuit for energizing between the working electrode and the counter electrode, a temperature sensor and a reduction current power supply circuit for detecting the temperature of the electrolyte in the cell And a control circuit for controlling the drive power supply circuit.
[0130]
Furthermore, in this embodiment, counter electrodes 17a and 17b and reference electrodes 27a and 27b are provided on the outer periphery of the working electrodes 2a to 2e and 3a to 3e. These counter electrodes 17a and 17b are obtained by forming a current collector layer by forming an ITO film on the substrates 4 and 5 to a thickness of about 200 nm by sputtering. The planar shapes of the working electrodes 2a to 2e and 3a to 3e and the counter electrodes 17a and 17b are substantially the same as those shown in FIG.
[0131]
The working electrodes 2a to 2e and 3a to 3e and the counter electrodes 17a and 17b of the bonded cell in this embodiment can be manufactured by the manufacturing process shown in FIGS.
[0132]
In addition to the working electrode and the counter electrode, it is also possible to provide reference electrodes 27a and 27b for monitoring the potential of these electrodes in order to control the driving of the elements. The manufacturing method in that case complies with the following counter electrode manufacturing method.
[0133]
First, a transparent conductive film 33 having an element composition ratio of indium and tin of about 9 (In: Sn = 9: 1) is formed on the substrate 31 shown in FIG. Sputtering is carried out using an ITO polycrystal containing 5% by weight of tin oxide as a target.
[0134]
Thereafter, a thin film of tin oxide is formed on the ITO film to a thickness of about 5 nm by the same sputtering method to form a transparent conductive film 33. At this time, a target is a polycrystalline body of tin oxide.
[0135]
Next, a chromium film 32 is formed on the transparent conductive film to a thickness of about 200 nm by the same sputtering method ((b)). A resist 34 is applied onto the substrate by spin coating ((c)), and then exposed / developed into a desired pattern with a mask ((d)).
[0136]
Thereafter, a part of the chromium layer 32 is etched, and the tin oxide layer of the transparent electrode film 33 is ion-milled (by applying a high frequency bias to the substrate in a plasma atmosphere to cause ions to collide, The ITO film is etched with a mixed acid of hydrochloric acid and nitric acid ((e)).
Thereafter, the remaining resist is peeled off to form a working electrode 2A and a counter electrode 17A having a desired planar shape and, if necessary, a reference electrode 27A ((f)).
[0137]
Next, a resist 34 is applied again ((g)), exposure / illusion is performed with a different mask ((h)), chrome is etched again, and an extraction electrode 35 is formed on the working electrode 2A. All chromium is removed from 17A and the reference electrode 27A ((i)).
[0138]
After the resist 34 is peeled off again ((j)), a silicon dioxide film 36 is formed by sputtering to cover the entire surface of each electrode ((k)).
[0139]
Thereafter, although not shown in FIG. 3 and FIG. 13, a black resist 37 is applied by spin coating for light shielding in order to prevent light from being transmitted through portions other than the working electrode 2A ((l)). Further, exposure / development was performed using another photomask to expose the working electrode 2A, the counter electrode 17A, and the reference electrode 27A, thereby obtaining a desired substrate ((m)).
[0140]
Then, silicon dioxide on the surface of the electrode portion not covered with the black resist is etched with a mixed solution of hydrofluoric acid and ammonium fluoride to expose the ITO surface of the electrode portion ((n)).
[0141]
Thereafter, the counter electrode 17A and the reference electrode 27A were screen-printed with a paste made of a carbon material and a cellulose-based binder, and silver powder (particle system 1 to 3 μm) having the same weight as the carbon weight dispersed therein, and these electrodes were Form ((o)).
[0142]
As shown in FIG. 3, the working electrodes 2a to 2e and 3a to 3e and the counter electrodes 17a and 17b are arranged so as to face each other, using a substrate obtained through the above-described manufacturing process and subjected to desired patterning, and spacers Then, the silver salt solution 1 was sealed inside, and a drive power supply circuit, a reduction current power supply circuit, a control circuit, and a temperature sensor were attached to obtain an optical device of the present invention.
[0143]
As the silver salt solution 1, a solution prepared by dissolving silver bromide 500 mM and sodium iodide 750 mM in a mixed solvent of dimethyl sulfoxide (DMSO) / dimethylacetamide (DMAc) = 50/50 was used.
[0144]
FIGS. 8 to 10 show changes in average transmittance of the examples and comparative examples. 8 shows the case at 22 ° C., FIG. 9 shows the case at 40 ° C., and FIG. 10 shows the case at 60 ° C. The case where silver was electrodeposited on the working electrode and then a predetermined reduction current was applied was used as an example, and the case where no current was supplied was used as a comparative example. The average transmittance was measured for 3600 seconds (1 hour).
[0145]
Although FIG. 8 shows the result at 22 ° C., in the comparative example, since no reduction current is passed, the deposited silver gradually dissolves, and as a result, the transmittance increases. On the other hand, in the embodiment, a reducing current of 6 μA is applied, so that the dissolved silver can be supplemented, and the increase in transmittance can be greatly suppressed.
[0146]
At 40 ° C., the temperature is high, so the spontaneous dissolution of the deposited silver is fast, and the transmittance changes from 20% to total transmission (100%) in about 2000 seconds. The transmittance can be suppressed to a small change. In this case, since the spontaneous dissolution of silver is fast, the reduction current is also 10 μA, which requires a larger current than at 22 ° C. (FIG. 9).
[0147]
Furthermore, when the temperature reaches 60 ° C., the spontaneous dissolution of the deposited silver becomes even faster, and when no reduction current is passed (comparative example), the transmittance changes from 20% to total transmission (100%) in about 1200 seconds. . On the other hand, when the reduction current is applied (Example), the change in transmittance is suppressed to be small although it is larger than the case of 22 ° C. or 40 ° C. The reduction current at this time was 18 μA (FIG. 10).
[0148]
As described above, the increase in the transmittance is effectively suppressed by energizing the reduction current, but the current value varies depending on the temperature. Therefore, the liquid temperature is monitored by the temperature sensor, and a reduction current suitable for the temperature is applied.
[0149]
From these results, in the Examples, it is possible to reduce an increase in transmittance due to spontaneous elution of electrodeposited silver, and it is possible to provide an optical device having excellent characteristics.
[0150]
In this embodiment, the electric field concentration problem can be solved as follows. That is, when the paste-like material is suppressed or applied to form the counter electrodes 17a and 17b, the corners of the edge of the counter electrode are rounded due to the fluidity and surface tension of the paste-like material, and there is substantially no corner. Counter electrodes 17a and 17b are formed. Therefore, the electric field concentration as described with reference to FIG. 15 is relaxed, and as a result, silver particles precipitated from the silver salt solution 1 are not formed larger. That is, the phenomenon that the silver particles float in the silver salt solution to reduce the transparency when the working electrode is decolored or the electrodes are short-circuited is prevented.
[0151]
Although the present invention has been described above according to the preferred embodiment, the above-described embodiment can be variously modified based on the technical idea of the present invention.
[0152]
For example, the electrode pattern shown in FIG. 2 is not limited to a concentric shape, but can be variously changed such as a stripe shape and a lattice shape. Different cells may be provided for each divided electrode.
[0153]
The optical device of the present invention can be applied not only to the light transmission type described above but also to a reflection type, and other known filter materials (for example, organic electrochromic materials, liquid crystals, electroluminescence materials, etc.) It is also possible to use in combination.
[0154]
Furthermore, the optical apparatus of the present invention can be widely applied to various optical systems such as an optical diaphragm of a CCD, for example, for light quantity adjustment in an optical communication device of an electrophotographic copying machine.
Furthermore, the optical device of the present invention can be applied to various image display elements that display characters and images in addition to the optical filter.
[0155]
【The invention's effect】
In the optical device and the driving method thereof according to the present invention, since a predetermined substance is electrodeposited on the working electrode and then energized to replenish the dissolved metal, the change in optical properties such as an increase in transmittance. That is, a decrease in the degree of shielding (or a decrease in reflectance) can be effectively suppressed.
[0156]
Further, according to the imaging apparatus of the present invention, since the optical device that can adjust the light amount by applying an electric field is applied to the light amount diaphragm, it does not require a large mechanical configuration unlike conventional mechanical light amount diaphragms, It is possible to reduce the size substantially to the effective range of the optical path, and to control the amount of light by the magnitude of the applied electric field to prevent diffraction and to effectively prevent image blurring.
[Brief description of the drawings]
FIG. 1A is a configuration diagram of an optical device of electrochemical dimming type according to an embodiment of the present invention, and FIGS. 1B and 1C are diagrams showing an example of a reduction current power supply circuit used in the device. FIG.
FIG. 2 is a longitudinal sectional view of an imaging apparatus in which the optical apparatus according to the embodiment of the present invention is applied to an optical aperture of a CCD camera.
FIG. 3 is a schematic structural diagram of an optical device according to another embodiment of the present invention (the electric system is omitted).
FIG. 4 is a flowchart showing the manufacturing process of the optical device.
FIG. 5 is a flowchart showing manufacturing steps of the optical device (continuing from FIG. 4).
FIG. 6 is a flowchart showing manufacturing steps of the optical device (continuing from FIG. 5).
FIG. 7 is a schematic configuration diagram of an electrochemical polymerization apparatus.
FIG. 8 is a graph showing a change in transmittance in Examples and Comparative Examples after silver is electrodeposited on a transparent electrode when the liquid temperature is 22 ° C.
FIG. 9 is a diagram showing a change in transmittance in Examples and Comparative Examples after silver is electrodeposited on a transparent electrode when the liquid temperature is 40 ° C.
FIG. 10 is a diagram showing a change in transmittance in Examples and Comparative Examples after silver is electrodeposited on a transparent electrode when the liquid temperature is 60 ° C.
11A and 11B show a conventional optical device of the same type, in which FIG. 11A is a cross section and FIG.
FIG. 12 is a perspective view of the optical device.
FIG. 13 is a cross-sectional view showing another example of a conventional optical device of the same type.
FIG. 14 is a plan view of the same.
FIG. 15 is a conceptual diagram showing the precipitation / growth / drop-off phenomenon of silver particles in a conventional optical device using a silver plate as a counter electrode.
[Explanation of symbols]
1, 21 ... Silver salt solution,
2a-2e, 3a-3e, 22, 23, 54 ... working electrode,
4, 5, 24, 25 ... transparent substrate, 6, 26 ... spacer,
17a, 17b, 52 ... counter electrode, 27a, 27b ... reference electrode, 41 ... DC power supply,
46 ... cell, 47 ... cathode, 48 ... anode, 50 ... drive power supply circuit,
51 ... Reduction current power supply circuit, 53 ... Temperature sensor, 55 ... Control circuit
70 ... CCD camera, 71 ... 1 group lens, 72 ... 2 group lens,
73 ... 3 group lens, 74 ... 4 group lens, 75 ... CCD package,
76. Electrochemical optical device

Claims (18)

Electrodeposition of a predetermined substance in the electrolytic solution by a driving power supply circuit comprising a working electrode, a counter electrode , and an electrolytic solution disposed between these electrodes, and connected between the working electrode and the counter electrode driving current for dissolution is energized, whereby the optical device for performing electrochemical dimming, soluble components of the electric Analyte substance in after electrodepositing said predetermined substance to the working electrode by the driving power source circuit As a power supply means for replenishing the power supply, a power supply circuit for power supply is connected between the working electrode and the counter electrode independently of the drive power supply circuit, and the drive power supply circuit and the power supply circuit for power supply are connected to each other. An optical device that is switched to operate independently of each other .   The optical apparatus according to claim 1, wherein the energization means is a constant current source. Wherein a sensor for detecting the temperature of the electrolyte solution, and a control circuit for controlling the voltage to current or applying energizing is provided by the energizing means on the basis of the temperature information, the optical device according to claim 1. The electrolyte and the sensor for detecting the temperature of a control circuit for controlling the drive current by the driving power source circuit based on the temperature information is provided, an optical device according to claim 1.   The optical device according to claim 1, wherein the working electrode is a transparent or translucent electrode having a transmittance of 70% or more in the visible region.   The optical device according to claim 1, wherein the electrolytic solution is a silver salt solution. Electrodeposition of a predetermined substance in the electrolytic solution by a driving power supply circuit comprising a working electrode, a counter electrode , and an electrolytic solution disposed between these electrodes, and connected between the working electrode and the counter electrode driving current for dissolution is energized, thereby driving method of an optical device for performing electrochemical dimming, the photoelectric Analyte substance in after electrodepositing said predetermined substance to the working electrode by the driving power source circuit As an energizing means for replenishing the dissolved component , an energizing power circuit is connected between the working electrode and the counter electrode independently of the driving power circuit, and the driving power circuit and the energizing power A method for driving an optical device, wherein the circuit is switched to operate independently of each other . The energization by the energizing means for replenishing the dissolved fraction of the conductive Analyte substance, row earthenware pots by the constant current, the driving method of an optical device according to claim 7. The temperature of the electrolytic solution detects and controls a current or a voltage by the energizing means for replenishing the dissolved fraction of the conductive Analyte substance on the basis of the temperature information, the driving method of an optical device according to claim 7. The method for driving an optical device according to claim 1 , wherein the temperature of the electrolytic solution is detected and the drive current by the drive power supply circuit is controlled based on the temperature information. The method for driving an optical device according to claim 7 , wherein the working electrode is a transparent or translucent electrode having a transmittance of 70% or more in the visible region. The method for driving an optical device according to claim 7 , wherein the electrolytic solution is a silver salt solution. Electrodeposition of a predetermined substance in the electrolytic solution by a driving power supply circuit comprising a working electrode, a counter electrode , and an electrolytic solution disposed between these electrodes, and connected between the working electrode and the counter electrode driving current for dissolution is energized, whereby an optical device that performs electrochemically dimming, in an optical path Te imaging apparatus odor which is provided for the light amount adjustment, the said working electrode by the driving power source circuit A power supply circuit for energization is provided between the working electrode and the counter electrode independently of the drive power supply circuit as an energization means for replenishing the dissolved substance of the electrodeposited substance after electrodepositing a predetermined substance. connected, the driving power source circuit and the image pickup device characterized in that the power supply circuit is switched to operate independently of each other for the energization. The imaging apparatus according to claim 13 , wherein the energization unit is a constant current source. The imaging apparatus according to claim 13 , further comprising: a sensor that detects a temperature of the electrolytic solution; and a control circuit that controls a current applied by the energization unit or a voltage applied based on the temperature information. The electrolyte and the sensor for detecting the temperature of a control circuit for controlling the drive current by the driving power source circuit based on the temperature information is provided, the imaging apparatus according to claim 13. The imaging apparatus according to claim 13 , wherein the working electrode is a transparent or translucent electrode having a transmittance of 70% or more in a visible region. The imaging device according to claim 13 , wherein the electrolytic solution is a silver salt solution.

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