JP4167342B2

JP4167342B2 - Image forming apparatus

Info

Publication number: JP4167342B2
Application number: JP09646599A
Authority: JP
Inventors: 正士廣木; 紀夫吉川
Original assignee: Toshiba Corp; Toshiba Tec Corp
Current assignee: Toshiba Corp; Toshiba Tec Corp
Priority date: 1999-04-02
Filing date: 1999-04-02
Publication date: 2008-10-15
Anticipated expiration: 2019-04-02
Also published as: JP2000293039A

Description

【０００１】
【発明の属する技術分野】
本発明は、液体現像剤を用いた湿式電子写真装置として適用される画像形成装置に関する。
【０００２】
【従来の技術】
液体現像剤を用いた湿式電子写真装置は、乾式電子写真装置では実現できない利点を有しており、近年その価値が見直されつつある。サブミクロンサイズの極めて微細なトナーを用いることができるため高画質を実現できること、少量のトナーで十分な画像濃度が得られるため経済的であるうえに印刷（例えばオフセット印刷）並みの質感を実現できること、比較的低温でトナーを用紙に定着出来るため省エネルギを実現できること、などが乾式に対する湿式電子写真装置の主な利点である。
【０００３】
一方、従来の液体トナーによる湿式電子写真技術にはいくつかの本質的な問題点が含まれており、そのために長い間乾式技術の独壇場を許してきた。これらの問題の一つとして、用紙への溶媒付着による環境問題であった。液体現像剤の電界転写においては、溶媒中を帯電粒子であるトナーが周知の電気泳動現象によって移動し、用紙へ転写させる。従って、電界転写においては所定量の溶媒が潜像保持体と用紙の間に介在していなければならず、その結果転写後の用紙には多量の溶媒が付着している。この溶媒は、熱による定着工程でその一部が揮発し、機外へ放出されるため、臭気や、蒸気の吸入による人体への悪影響といった問題を引き起こした。また、定着後に機外へ排紙された用紙は依然として多量の溶媒を含んでおり、アレルギ体質のユーザがこれに触れた場合には湿疹等の皮膚炎をもたらすことがあった。
【０００４】
このような問題を解決するため、潜像保持体から一旦中間転写媒体へ転写し、しかる後に用紙へ転写する方法が提案されている。米国特許第５，１４８，２２２号、同５，１６６，７３４、同５，２０８，６３７等には、潜像保持体から中間転写媒体へ電界によって転写し、しかる後に用紙へ圧力（及び熱）によって転写する方法が開示されている。中間転写媒体に付着した溶媒は、用紙への圧力転写に先立って、加熱やエアーの吸引などによって気化させたり吸い取ったりすることが可能であるため、用紙への溶媒付着を著しく低減できる。用紙へ圧力で転写する場合には溶媒の介在は不要であるため、このような改良が可能になるのである。
【０００５】
しかし、中間転写媒体上から蒸発した溶媒蒸気を装置内部で回収しなければ、蒸気として機外へ放出され、臭気や、蒸気の吸入による人体への悪影響といった問題が再び生じてしまう。
【０００６】
これに対し、特開昭４８−８３８３８では、用紙に可視像を転写した後、定着部で発生する溶媒蒸気を収集室に閉じ込めておき、この蒸気を含む空気を吸引口から冷却機構に導き、冷却することにより溶媒蒸気を液化することで、溶媒蒸気の機外への放出を防止している。
【０００７】
【発明が解決しようとする課題】
しかしながら、溶媒蒸気を完全に液化するまで冷却するには、多大な消費電力を消費してしまい、湿式電子写真装置の長所である省エネルギが実現できなくなってしまう。
【０００８】
このため、冷却器の後段の装置出口にフィルタを設けることが通常であるが、一般的な吸着フィルタ、例えば活性炭はフィルタを通過する溶媒蒸気を吸着吸着するが、同時に通過する水蒸気も吸着してしまい吸着性能が一定時間しか持続しない。このため、フィルタを長期間連続使用し得ることが困難で、ユーザやサービスマンが頻繁に交換しなければならないという問題がある。
【０００９】
本発明は上記実情に鑑みなされたもので、フィルタ部を長寿命化でき、しかも、溶媒蒸気を経済的に分解処理できるようにした画像形成装置を提供することを目的とする。
【００１０】
【課題を解決するための手段】
上記課題を解決するため、請求項１に記載の発明は、静電潜像を担持する像担持体と、この像担持体に担持された静電潜像に現像剤粒子と溶媒とからなる液体現像剤を供給して現像する現像手段と、この現像手段により現像された現像剤像を転写するとともに溶媒を蒸発させる中間転写体と、この中間転写体に転写された現像剤像を被転写材に転写させる転写手段と、前記蒸発された溶媒を吸引する吸引手段と、この吸引手段により吸引された溶媒蒸気を冷却する冷却手段と、この冷却手段から放出される溶媒蒸気を吸着するフィルタ部と、このフィルタ部に吸着された溶媒蒸気に紫外線を照射して分解し、放出させる紫外線照射手段とを具備する。
【００１１】
請求項２記載の発明は、静電潜像を担持する像担持体と、この像担持体に担持された静電潜像に現像剤粒子と溶媒とからなる液体現像剤を供給して現像する現像手段と、この現像手段により現像された現像剤像を転写するとともに溶媒を蒸発させる中間転写体と、この中間転写体に転写された現像剤像を被転写材に転写させる転写手段と、前記蒸発された溶媒を吸引する吸引手段と、この吸引手段により吸引された溶媒蒸気を冷却する冷却手段と、この冷却手段から放出される溶媒蒸気を吸着するもので、無機及び有機の繊維に酸化チタン粉末を担持させてなるフィルタ部と、このフィルタ部に吸着された溶媒蒸気に紫外線を照射して分解し、放出させる紫外線照射手段とを具備する。
【００１２】
請求項３記載の発明は、静電潜像を担持する像担持体と、この像担持体に担持された静電潜像に現像剤粒子と溶媒とからなる液体現像剤を供給して現像する現像手段と、この現像手段により現像された現像剤像を転写するとともに溶媒を蒸発させる中間転写体と、この中間転写体に転写された現像剤像を被転写材に転写させる転写手段と、前記蒸発された溶媒を吸引する吸引手段と、この吸引手段により吸引される溶媒蒸気を冷却する冷却手段と、この冷却手段により冷却された溶媒蒸気を流す第１及び第２の流路と、これら第１及び第２の流路を開閉する第１及び第２の開閉弁と、前記第１及び第２の流路の排気側にそれぞれ設けられ、溶媒蒸気を吸着する第１及び第２のフィルタと、これら第１及び第２のフィルタに吸着された溶媒蒸気に紫外線を照射して分解し、放出させる第１及び第２の紫外線照射手段と、前記第１及び第２の開閉弁の開閉さらに前記第１及び第２の紫外線照射手段による紫外線照射を前記溶媒蒸気の発生量に応じて制御する制御手段とを具備する。
【００１３】
請求項４記載の発明は、静電潜像を担持する像担持体と、この像担持体に担持された静電潜像に現像剤粒子と溶媒とからなる液体現像剤を供給して現像する現像手段と、この現像手段により現像された現像剤像を転写するとともに溶媒を蒸発させる中間転写体と、この中間転写体に転写された現像剤像を被転写材に転写させる転写手段と、前記蒸発された溶媒を吸引する吸引手段と、この吸引手段により吸引される溶媒蒸気を冷却する冷却手段と、この冷却手段により冷却された溶媒蒸気を流す第１及び第２の流路と、これら第１及び第２の流路を開閉する第１及び第２の開閉弁と、前記第１及び第２の流路の排気側にそれぞれ設けられ、溶媒蒸気を吸着する第１及び第２のフィルタ部と、これら第１及び第２のフィルタ部に吸着された溶媒蒸気に紫外線を照射して分解し、放出させる第１及び第２の紫外線照射手段と、前記第１及び第２のフィルタを通過した溶媒蒸気の濃度を検出する検出センサと、前記第１及び第２の開閉弁の開閉さらに前記第１及び第２の紫外線照射手段による紫外線照射を前記検出センサの検出濃度に応じて制御する制御手段とを具備する。
【００１４】
請求項５記載の発明は、静電潜像を担持する像担持体と、この像担持体に担持された静電潜像に現像剤粒子と溶媒とからなる液体現像剤を供給して現像する現像手段と、この現像手段により現像された現像剤像を転写するとともに溶媒を蒸発させる中間転写体と、この中間転写体に転写された現像剤像を被転写材に転写させる転写手段と、前記蒸発された溶媒を吸引する吸引手段と、この吸引手段により吸引される溶媒蒸気を冷却する冷却手段と、この冷却手段により冷却された溶媒蒸気を流す第１及び第２の流路と、これら第１及び第２の流路を開閉する第１及び第２の開閉弁と、前記第１及び第２の流路の排気側にそれぞれ設けられ、溶媒蒸気を吸着する第１及び第２のフィルタ部と、これら第１及び第２のフィルタ部に吸着された溶媒蒸気に紫外線を照射して分解し、放出させる第１及び第２の紫外線照射手段と、前記第１及び第２の開閉弁を選択的に開閉することにより、前記第１及び第２のフィルタ部における溶媒蒸気の吸着と分解時間を制御する制御手段とを具備する。
【００１５】
請求項６記載の発明は、静電潜像を担持する像担持体と、この像担持体に担持された静電潜像に現像剤粒子と溶媒とからなる液体現像剤を供給して現像する現像手段と、この現像手段により現像された現像剤像を転写するとともに溶媒を蒸発させる中間転写体と、この中間転写体に転写された現像剤像を被転写材に転写させる転写手段と、前記蒸発された溶媒を吸引する吸引手段と、この吸引手段により吸引される溶媒蒸気を冷却する冷却手段と、この冷却手段により冷却された溶媒蒸気を流す第１及び第２の流路と、これら第１及び第２の流路を開閉する第１及び第２の開閉弁と、前記第１及び第２の流路の排気側にそれぞれ設けられ、溶媒蒸気を吸着する第１及び第２のフィルタ部と、これら第１及び第２のフィルタ部に吸着された溶媒蒸気に紫外線を照射して分解し、放出させる第１及び第２の紫外線照射手段と、前記第１及び第２のフィルタを通過した溶媒蒸気の濃度を検出する検出センサと、この検出センサの検出濃度に応じて、前記第１及び第２の開閉弁を選択的に開閉することにより、前記第１及び第２のフィルタ部における溶媒蒸気の吸着と分解時間を制御する制御手段とを具備する。
【００１６】
請求項７記載の発明は、静電潜像を担持する像担持体と、この像担持体に担持された静電潜像に現像剤粒子と溶媒とからなる液体現像剤を供給して現像する現像手段と、この現像手段により現像された現像剤像を転写するとともに溶媒を蒸発させる中間転写体と、この中間転写体に転写された現像剤像を被転写材に転写させる転写手段と、前記蒸発された溶媒を吸引する吸引手段と、この吸引手段により吸引される溶媒蒸気を冷却する冷却手段と、この冷却手段により冷却された溶媒蒸気を流す第１及び第２の流路と、これら第１及び第２の流路を開閉する第１及び第２の開閉弁と、前記第１及び第２の流路の排気側にそれぞれ設けられ、溶媒蒸気を吸着する第１及び第２のフィルタ部と、これら第１及び第２のフィルタ部に吸着された溶媒蒸気に紫外線を照射して分解し、放出させる第１及び第２の紫外線照射手段と、前記第１及び第２のフィルタの排気側を開閉する第１及び第２のシャッタと、前記第１及び第２の開閉弁さらに前記第１及び第２のシャッタを選択的に開閉することにより、前記第１及び第２のフィルタ部における溶媒蒸気の吸着と分解時間を制御する制御手段とを具備する。
【００１７】
【発明の実施の形態】
以下、本発明を図面に示す一実施の形態を参照して説明する。
【００１８】
図１は湿式電子写真記録装置の画像形成部を概略的に示すものである。
【００１９】
図１中１は導電性基体の上に有機系もしくはアモルファスシリコン系の感光層を形成した回転自在な潜像保持体としての感光体ドラムである。この感光体ドラム１の周囲部にはその回転方向に沿って順次、周知のコロナ帯電器もしくはスコロトロンの第１〜第４の帯電器２ａ〜２ｄ、画像変調されたレーザビームを照射する第１〜第４のレーザ露光部３ａ〜３ｄ、及び異なる色の現像剤粒子であるトナーと溶媒とからなる液体現像剤を供給する第１〜第４の現像装置４ａ〜４ｄが配設されている。
【００２０】
また、感光体ドラム１の上面部には中間転写媒体６が転接され、さらに、中間転写媒体６の上面部にはバックアップローラ８が圧接されている。この中間転写体６とバックアップローラ８とにより転写装置５が構成され、用紙は中間転写媒体６とバックアップローラ８との間に搬送されるようになっている。
【００２１】
画像形成時には、感光体ドラム１の周面が第１の帯電器２ａによって均一に帯電された後、第１のレーザ露光部３ａによって画像変調されたレーザビームが照射されて露光され、表面に静電潜像が形成される。しかる後、第１の現像装置４ａから液体現像剤が供給され静電潜像の可視像化と余剰現像剤のスクイーズが行なわれる。静電潜像に付着した液体現像剤（もしくはトナー）は、そのまま転写工程に至り、転写装置５によって用紙に転写されても良いが、ここでは引き続き第２の帯電器２ｂと第２のレーザ露光部３ｂで第２の静電潜像を形成し、第１の現像装置４ａに収納されている液体現像剤とは異なる色の第２の現像剤を第２の現像装置４ｂから供給してこれを現像する。従って、第２現像の後には、感光体ドラム１上には２色のトナー像が形成されている。同様にして、第３、第４の現像が行なわれ、感光体ドラム１にはフルカラーのトナー像が形成される。このトナー像は、転写装置５によって用紙に転写されるが、図１に例示するように中間転写媒体６を介して被転写媒体（用紙）１０に転写される。このことで、直接用紙に転写する場合より、画像の品質が被転写媒体の影響を受けなくなる。感光体ドラム１から中間転写媒体６への転写、および中間転写媒体６から用紙１０への転写においては、いずれも電界による転写かもしくは圧力（及び熱）による転写のいずれかを用いることが出来る。
【００２２】
この実施の形態では、中間転写媒体６と用紙１０を密着させるために、バックアップローラ８で用紙を中間転写媒体６に押し付けている。また、液体現像剤は一般に室温で用紙に定着できるものも多いが、バックアップローラ８をヒータ９により加熱して、転写性、定着性を向上させるとともに、後述するように、溶媒を蒸発させている。このような画像形成プロセスは、例えば米国特許５，５７０，１７３などに開示されており、従来から公知のプロセスである。
【００２３】
図２に湿式電子写真記録装置の溶媒蒸気回収部を示す。
【００２４】
感光体ドラム１上で上記したように現像動作が行なわれると、現像液中のトナー（粒径０．１〜０．５μｍの帯電した色材粒子）により可視像が形成されるとともに、現像液中に溶媒（商品名アイソパー、ノルパー等の導電度の低い無極性の炭化水素）の層も形成される。この溶媒層を用紙１０に転写するまでに除去しないと、用紙１０に付着し機外へ放出してしまう。
【００２５】
そこで、中間転写媒体６は転写を促進するためにヒータ９で加熱、昇温されているので、この熱を利用して溶媒を中間転写媒体６上で蒸発させる。このため、溶媒を蒸発させるためだけに別の加熱源を設ける必要がなく、消費電力が増加することがない。溶媒蒸気は、中間転写媒体６近傍で発生するので、その位置にケーシング１１が設けられており、ケーシング１１内で発生した蒸気は空気とともに樹脂チューブ等の経路を通って冷却部１３に導かれる。溶媒蒸気を冷却部１３に吸引する動力は、冷却部１３より下流に設けられた吸引手段としての例えばブロワや真空ポンプ１４による。冷却部１３に導かれた溶媒蒸気は冷却されると飽和蒸気圧が下がり、余剰の溶媒が液化し、溶媒回収容器１５に流れ落ちる。この時、冷却部１３内の空気中の水蒸気も冷却され、水となって溶媒回収容器１５に貯まる。ここでは、中間転写媒体６を５０〜１００℃に加熱し溶媒を蒸発させ、冷却部で０〜１５℃に冷却して液化させている。しかし、溶媒蒸気を０℃まで冷却しても溶媒の飽和蒸気圧は０ではないので、ポンプ１４の排気口からある程度の溶媒蒸気が放出される。これは、更に下流に設けられた複数（第１及び第２の）のフィルタ部１６ａ，１６ｂにより吸着、分解され、溶媒蒸気を含まない空気が機外へ放出されることになる。
【００２６】
次に、フィルタ部１６ａ，１６ｂについて説明する。
【００２７】
フィルタ部１６ａ，１６ｂは無機繊維、および有機繊維に酸化チタン粉体を担持させたものである。溶媒蒸気を含んだ空気がこの繊維を通過するときに、溶媒蒸気が繊維表面、つまり酸化チタンに接触すると付着し、この状態で紫外線を照射すると酸化チタンの酸化力で表面に接触した物質、この場合は炭化水素が酸化分解し、二酸化炭素と水になる。このため、一般的な吸着フィルタのように寿命がなく、ほぼ永久的に使用することができる。酸化チタン光接触による分解機能は、紫外線を受光し、物質と接触して初めて生じるので、フィルタ部１６ａ，１６ｂが高い分解性能を持つにはフィルタ部１６ａ，１６ｂの表面積を増やし、その表面に紫外線を効率的に照射し、物質を頻繁にフィルタ部１６ａ，１６ｂに接触させることが必要である。
【００２８】
図３及び図４はフィルタ部１６ａ，１６ｂによる溶媒蒸気の分解を示すものである。
【００２９】
溶媒蒸気２０がフィルタ部１６ａ，１６ｂの繊維２１表面に接触して付着する。これと同時に紫外線２２が照射され、溶媒は最終分解物質２３である水と二酸化炭素になり、空気中に放出される。
【００３０】
ここで、フィルタ部１６ａ，１６ｂは繊維２１が何十にも織り重なったものだと表面積は増えるが、紫外線２２が内部まで届かないので、分解作用が生じない。このため、繊維２１は紫外線２２が内部まで到達できる厚さ（重なり数）でなければならない。
【００３１】
また、溶媒蒸気２０が集中的に接触するような領域があると、溶媒を分解するより速く付着が生じてしまい、このような状態では、フィルタ繊維表面の余剰の溶媒が再び繊維から離脱して機外へ漏れてしまう。このようなことが生じないように、フィルタ部１６ａ，１６ｂの全面に均一に溶媒蒸気が透過するようにすることも必要である。
【００３２】
図５はポンプ１４からフィルタ部１６ａ，１６ｂまでの構成を詳細に示すものである。
【００３３】
転写ローラ近傍で発生した溶媒蒸気はケーシング１１から冷却部１３を通り、ポンプ１４により更に下流のフィルタ部１６ａ，１６ｂに流れ込み、そのフィルタ３０ａ，３０ｂを透過した空気が機外へ放出される。この工程において、冷却部１３で液化しなかった溶媒蒸気はフィルタ３０ａ，３０ｂに付着する。フィルタ３０ａ，３０ｂのケーシング２９ａ，２９ｂ内部には紫外線ランプ３１ａ，３１ｂが設けてあり、フィルタ３１ａ，３１ｂの表面を照射するようになっている。また、ポンプ１４からフィルタ部１６ａ，１６ｂまでの経路の途中には、制御部３２に接続されている電磁バルブ３３ａ，３３ｂがそれぞれ設けてあり、フィルタ部１６ａ，１６ｂを流れる溶媒蒸気の通過、遮断を制御する。この実施の形態では、経路は２つになっているが、３つ以上でもよい。
【００３４】
次に、印刷動作とフィルタ部１６ａ，１６ｂの溶媒蒸気の吸着、分解動作について図６を参照して説明する。
【００３５】
まず、第１の電磁バルブ３３ａを開放して第１の紫外線ランプ３１ａをオンさせ、また、第２の電磁バルブ３３ｂを閉鎖して第２の紫外線ランプ３１ｂをオフさせる（ステップＳ１）。印刷動作が始まると、中間転写ローラ６で加熱された現像液中のキャリア液である有機溶媒が蒸発し蒸気となる。この蒸気はポンプ１４の吸引力により冷却部１３を通り、第１の電磁バルブ３３ａが開放している第１のフィルタ３０ａを通過し吸着する。この吸着された溶媒蒸気は第１のフィルタ部１６ａに第１の紫外線ランプ３１ａから紫外線が照射されることにより、水と二酸化炭素に分解される。印刷動作が終了しても第１のフィルタ部１６ａの紫外線照射は継続する。これは、フィルタ３０ａの吸着能力（単位時間にフィルタ３０ａに付着する溶媒量）が分解能力（単位時間に分解される溶媒量）より高いためである。ついで、連続印刷か否かが判別され（ステップＳ２）、連続印刷の場合には、第１の電磁バルブ３３ａとともに、第２の電磁バルブ３３ｂも開放され（ステップＳ３）、第２のフィルタ部１６ｂへも溶媒蒸気を流す。また、これと同時に第１の紫外線ランプ３１とともに第２のフィルタ部１６ｂの第２の紫外線ランプ３１ｂをも照射し、第１及び第２のフィルタ部１６ａ，ｂの両方で溶媒蒸気の吸着、分解を行なう。
【００３６】
通常の複写機やプリンタでは連続使用する頻度は少なく、印刷を行なっていない時間がかなりある。このような状態で溶媒蒸気の発生量が少なく、複数のフィルタ部１６ａ，１６ｂの全てを使用しなくても、溶媒蒸気の吸着、分解処理が可能である。従って、余分な紫外線ランプを点灯する必要がなく、省電力化を図ることができるとともに、紫外線によるフィルタやケースの劣化を防止することができる（例えば電磁バルブがなく、２つのフィルタ部１６ａ，１６ｂに溶媒蒸気が流れ込むとすると常に全ての紫外線ランプ３１ａ，３１ｂを点灯しなければならない）。
【００３７】
図７は上記した印刷動作とフィルタ部１６ａ，１６ｂの溶媒蒸気の吸着、分解の他の動作例を示すものである。
【００３８】
溶媒蒸気の発生と回収の経路は図５で示した構成と同じである。
【００３９】
まず、第１の電磁バルブ３３ａを開放して第１の紫外線ランプ３１ａをオンさせ、第２の電磁バルブ３３ｂを閉鎖して第２の紫外線ランプ３１ｂをオフさせる（ステップＳ１１）。印刷動作が始まると、中間転写ローラ６で加熱された現像液中の有機溶媒が蒸発し蒸気となる。この蒸気はポンプ１４により冷却部１３を通り、第１の電磁バルブ３３ａが開放している第１のフィルタ部３０ａを通過し、吸着する。この吸着された溶媒蒸気は第１の紫外線ランプ３１ａから発せられた紫外線が照射されることにより、水と二酸化炭素に分解される。印刷動作が終了しても第１のフィルタ部１６ａの紫外線照射は継続する。溶媒蒸気の発生量は印刷枚数で決まるので、発生した溶媒を分解する時間紫外線を照射したら、照射を終える。ついで、第２のフィルタ部３０ｂに溶媒があるか否かが判別され（ステップ１２）、溶媒蒸気があれば第２の紫外線ランプ３１ｂから紫外線が発せられ（ステップ１３）、溶媒蒸気がなければ、一定枚数或いは連続印刷であるか否かが判別される（ステップ１４）。一定枚数或いは連続印刷でなければステップＳ１１に戻り、一定枚数或いは連続印刷であれば（例えば、装置内の印刷枚数を計測するカウンタが一定時間内に所定値に達成すると）、第１の電磁バルブ３３ａを閉塞して第１の紫外線ランプ３１ａをオンさせ、第２の電磁バルブ３３ｂを開放して第２の紫外線ランプ３１ｂをオンさせる（ステップＳ１５）。これにより、第１のフィルタ部１６ａでは溶媒の分解だけが行なわれ、第２のフィルタ部１６ｂでは吸着と分解が行なわれる。ここでは、連続的で印刷した場合、つまり、単位時間当たりの溶媒蒸気発生量が最も多い場合に第１のフィルタ部１６ａで分解が終了するまで、第２のフィルタ部１６ｂの吸着が飽和状態にならないようにフィルタ３０ａ，３０ｂの面積、紫外線の光量、蒸気の流量を設定してある。
【００４０】
フィルタ３０ａ，３０ｂの吸着能力が分解能力より高いと、分解するより吸着が大幅に上回り、フィルタ３０ａ，３０ｂに吸着している溶媒の最外周部から再び溶媒蒸気が生じたり、溶媒がフィルタ３０ａ，３０ｂに吸着せずそのまま通過してしまうことが生じてしまう。本方式のように、溶媒を吸着させる時間よりも分解する時間を長く取ることで、吸着が飽和状態になると次のフィルタを使用するので、溶媒が漏れることがない。
【００４１】
上記したように第１のフィルタ部１６ａで溶媒の分解が行われたのち、第１のフィルタ１６ａに溶媒蒸気が有るか否かが判別され（ステップＳ１６）、溶媒蒸気がある場合には紫外線が照射され（ステップＳ１７）、溶媒蒸気がない場合には、一定枚数或いは連続印刷であるか否かが判別される（ステップ１８）。一定枚数或いは連続印刷でなければステップＳ１５に戻り、一定枚数或いは連続印刷であればステップＳ１１に戻る。
【００４２】
図８は本発明の第２の実施の形態を示すものである。
【００４３】
なお、上記実施の形態で示した部分と同一部分については、同一番号を付して説明する。
【００４４】
この実施の形態では、第１及び第２のフィルタ部１６ａ，１６ｂの第１及び第２のフィルタ３０ａ，３０ｂ下流に溶媒蒸気の濃度センサ４０ａ，４０ｂが取り付けてある。この濃度センサ４０ａ，４０ｂは、酸化スズ（＝ＳｎＯ2 ）を主成分とする焼結型のｎ型半導体ガスセンサを用いている。これは還元性ガスがセンサ４０ａ，４０ｂに吸着すると、電気抵抗値が小さくなる現象を利用している。ここでは、それぞれの濃度センサ４０ａ，４０ｂの出力により、溶媒蒸気の経路を切り替える。例えば、印刷動作が始まる前に、第１の電磁バルブ３３ａを開放し、第２の電磁バルブ３３ｂを閉鎖し、第１のフィルタ部１６ａの第１の紫外線ランプ３１ａを照射する。溶媒蒸気は第１のフィルタ部１６ａに流れ、吸着、分解される。
【００４５】
印刷動作頻度が低く溶媒蒸気の発生量が少ない場合は、第１のフィルタ部１６ａだけで十分処理できるが、発生量が増加すると溶媒蒸気が第１のフィルタ部１６ａを通過してしまう。このような状況になると、第１のフィルタ部１６ａの下流に設けてある第１の濃度センサ４０ａは第１のフィルタ部１６ａを通過する溶媒蒸気の量が増加したことを検知し、これを受けて第２の電磁バルブ３３ｂも開放し、紫外線を照射することで、第２のフィルタ部１６ｂでも吸着、分解が行なわれる。この場合も、前に述べたように、発生量が少ない時には複数のフィルタ部のうち幾つかを使用することで吸着、分解処理を行なうので、余分な紫外線ランプを照射しないので省電力、長寿命化が図れる。
【００４６】
また、濃度センサ４０の出力によって蒸気発生量が多いことを検知することで、図７で説明したようにフィルタを切り替えて使用することによっても、上記した実施の形態と同様の効果が得られる。
【００４７】
図９は本発明の第３の実施の形態を示すものである。
【００４８】
なお、上記実施の形態で示した部分と同一部分については、同一番号を付して説明する。
【００４９】
溶媒蒸気の発生と回収の経路は図５と同様の構成で、印刷動作とフィルタの溶媒蒸気の吸着、分解動作は図７で示したものと同じである。
【００５０】
まず、印刷動作が始まる前に、第１の電磁バルブ３３ａを開放し、第２の電磁バルブ３３ｂを閉鎖する。発生した蒸気は第１のフィルタ３０ａを通過して吸着し、同時に第１のフィルタ部１６ａの第１の紫外線ランプ３１ａから紫外線を照射することで水と二酸化炭素に分解される。
【００５１】
次に、連続的、または、一定時間内に所定枚数印刷した場合、例えば、装置内の印刷枚数を計測するカウンタが一定時間内に所定値に達成したり、図示していないフィルタ下流のセンサが排出される溶媒蒸気の濃度が所定値に達したことを検知すると、第１の電磁バルブ３３ａを閉鎖して第２の電磁バルブ３３ｂを開放し、これと同時に第２のフィルタ部１６ｂ内部の第２の紫外線ランプ３１ｂを点灯する。
【００５２】
また、この時、第１のフィルタ部１６ａの出口の第１のシャッタ５０ａが図示しない駆動装置により空気の排気口を閉鎖し、第１のフィルタ部１６ａは密閉された状態になる。このため、第１のフィルタ部１６ａで溶媒蒸気の分解動作のみを行なっている時には、空気の流れが無くなり、フィルタ１６ａに吸着している溶媒がフィルタ１６ａから離脱し漏れることはない。
【００５３】
【発明の効果】
本発明は、以上説明したように、冷却手段から放出される溶媒蒸気をフィルタ部で吸着し、この吸着した溶媒蒸気に紫外線を照射して分解するため、従来のように、フィルタ部が水蒸気を吸着することがなく、長期間連続して使用することができ、フィルタ部の交換作業を削減することができる。
【００５４】
また、溶媒蒸気の発生量に応じて第１及び第２の開閉弁の開閉さらに、第１及び第２の紫外線照射手段による紫外線照射を制御するため、溶媒蒸気の発生量が少ない場合には、第１及び第２のフィルタ部のいずれか一方に溶媒蒸気を送って吸着、分解させることができ、省電力が可能になるとともに、フィルタの劣化も防止できる。
【００５５】
さらに、第１及び第２の開閉弁を選択的に開閉することにより、前記第１及び第２のフィルタ部における溶媒蒸気の吸着と分解時間を制御するため、フィルタ部において溶媒蒸気を吸着させる時間よりも分解させる時間を長くすることができ、フィルタ部から溶媒蒸気を放出させてしまうことがない。
【００５６】
また、第１及び第２のフィルタ部の排気側を開閉する第１及び第２のシャッタを備えるため、フィルタ部からの溶媒蒸気の放出をより一層確実に防止することができる。
【図面の簡単な説明】
【図１】本発明の一実施の形態である湿式電子写真装置の画像形成部を示す全体構成図。
【図２】溶媒蒸気の回収部を示す構成図。
【図３】フィルタの溶媒蒸気の吸着動作を示す図。
【図４】フィルタの溶媒蒸気の分解動作を示す図。
【図５】フィルタ部及び溶媒蒸気の経路を示す図。
【図６】印刷動作と溶媒蒸気の回収動作を示すフローチャート。
【図７】印刷動作と溶媒蒸気の他の回収動作を示すフローチャート。
【図８】本発明の第２の実施の形態であるフィルタ部及び蒸気経路を示す図。
【図９】本発明の第３の実施の形態であるフィルタ部及び蒸気経路を示す図。
【符号の説明】
１…感光体ドラム（潜像保持体）
５…転写装置
６…中間転写体（転写手段）
８…バックアップローラ（転写手段）
１０…用紙（被転写媒体）
１３…冷却部
１４…ポンプ（吸引手段）
１６ａ…第１のフィルタ部
１６ｂ…第２のフィルタ部
３０ａ…第１のフィルタ
３０ｂ…第２のフィルタ
３１ａ…第１の紫外線照射手段（第１の紫外線ランプ）
３１ｂ…第２の紫外線照射手段（第２の紫外線ランプ）
３２…制御手段
３３ａ…第１の電磁バルブ（第１の開閉弁）
３３ｂ…第２の電磁バルブ（第２の開閉弁）
４０ａ…第１の濃度センサ（検出センサ）
４０ｂ…第２の濃度センサ（検出センサ）
５０ａ…第１のシャッタ
５０ｂ…第２のシャッタ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus applied as a wet electrophotographic apparatus using a liquid developer.
[0002]
[Prior art]
A wet electrophotographic apparatus using a liquid developer has advantages that cannot be realized by a dry electrophotographic apparatus, and its value is being reviewed in recent years. Submicron-size extremely fine toner can be used, so high image quality can be achieved, and a small amount of toner can provide sufficient image density, so that it is economical and can achieve a texture similar to printing (for example, offset printing). The main advantage of the wet type electrophotographic apparatus with respect to the dry type is that the toner can be fixed on the paper at a relatively low temperature and energy saving can be realized.
[0003]
On the other hand, the conventional wet electrophotographic technology using liquid toner includes some essential problems, and for this reason, it has long allowed a dry technology to be used alone. One of these problems is an environmental problem due to solvent adhesion to the paper. In electric field transfer of a liquid developer, toner as charged particles moves in a solvent by a well-known electrophoretic phenomenon and is transferred onto a sheet. Therefore, in electric field transfer, a predetermined amount of solvent must be interposed between the latent image holding member and the sheet, and as a result, a large amount of solvent adheres to the sheet after transfer. A part of this solvent is volatilized in the fixing process by heat and released to the outside of the apparatus, which causes problems such as odor and adverse effects on human bodies due to inhalation of vapor. Further, the paper discharged out of the machine after fixing still contains a large amount of solvent, and when an allergic user touches it, dermatitis such as eczema may occur.
[0004]
In order to solve such problems, a method has been proposed in which the latent image holding member is once transferred to an intermediate transfer medium and then transferred to a sheet. U.S. Pat. Nos. 5,148,222, 5,166,734, 5,208,637, etc., transfer from a latent image carrier to an intermediate transfer medium by an electric field and then pressure (and heat) to the paper. Discloses a method for transferring. Since the solvent adhering to the intermediate transfer medium can be vaporized or sucked by heating or air suction prior to the pressure transfer to the sheet, the adhesion of the solvent to the sheet can be significantly reduced. In the case of transferring to a sheet by pressure, such an improvement is possible because the intervention of a solvent is unnecessary.
[0005]
However, if the solvent vapor evaporated from the intermediate transfer medium is not collected inside the apparatus, it is discharged as vapor to the outside of the apparatus, and problems such as odor and adverse effects on the human body due to the inhalation of the vapor will occur again.
[0006]
On the other hand, in Japanese Patent Laid-Open No. 48-83838, after a visible image is transferred to a sheet, solvent vapor generated in the fixing unit is confined in a collection chamber, and air containing this vapor is guided from a suction port to a cooling mechanism. The solvent vapor is liquefied by cooling to prevent the solvent vapor from being released to the outside.
[0007]
[Problems to be solved by the invention]
However, in order to cool the solvent vapor until it is completely liquefied, a great amount of power is consumed, and energy saving, which is an advantage of the wet electrophotographic apparatus, cannot be realized.
[0008]
For this reason, it is normal to provide a filter at the outlet of the apparatus downstream of the cooler. However, a general adsorption filter, for example activated carbon, adsorbs and adsorbs solvent vapor that passes through the filter, but also adsorbs water vapor that passes simultaneously. The adsorption performance lasts only for a certain time. For this reason, it is difficult to use the filter continuously for a long period of time, and there is a problem that a user or a service person must frequently replace the filter.
[0009]
The present invention has been made in view of the above circumstances, and an object thereof is to provide an image forming apparatus capable of extending the life of a filter unit and economically decomposing solvent vapor.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, it is described in claim 1. invention Includes an image carrier that carries an electrostatic latent image, a developing unit that supplies a liquid developer composed of developer particles and a solvent to the electrostatic latent image carried on the image carrier, and develops the developer. An intermediate transfer body that transfers the developer image developed by the means and evaporates the solvent, a transfer means that transfers the developer image transferred to the intermediate transfer body to the transfer material, and sucks the evaporated solvent Suction means, a cooling means for cooling the solvent vapor sucked by the suction means, a filter part for adsorbing the solvent vapor released from the cooling means, and the solvent vapor adsorbed on the filter part are irradiated with ultraviolet rays And then disassemble To release And ultraviolet irradiation means.
[0011]
Claim 2 invention An image carrier that carries an electrostatic latent image When, A developing means for supplying and developing a liquid developer comprising developer particles and a solvent to the electrostatic latent image carried on the image carrier, and transferring the developer image developed by the developing means and removing the solvent. Intermediate transfer body to be evaporated, transfer means for transferring the developer image transferred to the intermediate transfer body onto a transfer material, suction means for sucking the evaporated solvent, and solvent vapor sucked by the suction means A cooling means for cooling the solvent, a solvent vapor released from the cooling means, a filter part in which titanium oxide powder is supported on inorganic and organic fibers, and a solvent vapor adsorbed on the filter part. Decompose by irradiating with ultraviolet rays And release And ultraviolet irradiation means.
[0012]
Claim 3 invention An image carrier that carries an electrostatic latent image When, A developing means for supplying and developing a liquid developer comprising developer particles and a solvent to the electrostatic latent image carried on the image carrier, and transferring the developer image developed by the developing means and removing the solvent. Intermediate transfer body to be evaporated, transfer means for transferring the developer image transferred to the intermediate transfer body onto a transfer material, suction means for sucking the evaporated solvent, and solvent vapor sucked by the suction means Cooling means for cooling the first, second flow paths for flowing the solvent vapor cooled by the cooling means, first and second on-off valves for opening and closing the first and second flow paths, The first and second filters provided on the exhaust side of the first and second flow paths, respectively, and the solvent vapor adsorbed by the first and second filters are irradiated with ultraviolet rays. Disassemble And release First and second ultraviolet irradiation means, and control means for controlling the opening and closing of the first and second on-off valves and the ultraviolet irradiation by the first and second ultraviolet irradiation means according to the amount of the solvent vapor generated It comprises.
[0013]
Claim 4 invention An image carrier that carries an electrostatic latent image When, A developing means for supplying and developing a liquid developer comprising developer particles and a solvent to the electrostatic latent image carried on the image carrier, and transferring the developer image developed by the developing means and removing the solvent. Intermediate transfer body to be evaporated, transfer means for transferring the developer image transferred to the intermediate transfer body onto a transfer material, suction means for sucking the evaporated solvent, and solvent vapor sucked by the suction means Cooling means for cooling the first, second flow paths for flowing the solvent vapor cooled by the cooling means, first and second on-off valves for opening and closing the first and second flow paths, UV light is applied to the first and second filter parts, which are provided on the exhaust side of the first and second flow paths, respectively, and adsorb the solvent vapor, and the solvent vapor adsorbed to the first and second filter parts. Irradiate and decompose And release First and second ultraviolet irradiation means, a detection sensor for detecting the concentration of solvent vapor that has passed through the first and second filters, opening and closing of the first and second on-off valves, and the first and second Control means for controlling the ultraviolet irradiation by the two ultraviolet irradiation means according to the detection density of the detection sensor.
[0014]
Claim 5 invention An image carrier that carries an electrostatic latent image When, A developing means for supplying and developing a liquid developer comprising developer particles and a solvent to the electrostatic latent image carried on the image carrier, and transferring the developer image developed by the developing means and removing the solvent. Intermediate transfer body to be evaporated, transfer means for transferring the developer image transferred to the intermediate transfer body onto a transfer material, suction means for sucking the evaporated solvent, and solvent vapor sucked by the suction means Cooling means for cooling the first, second flow paths for flowing the solvent vapor cooled by the cooling means, first and second on-off valves for opening and closing the first and second flow paths, UV light is applied to the first and second filter parts, which are provided on the exhaust side of the first and second flow paths, respectively, and adsorb the solvent vapor, and the solvent vapor adsorbed to the first and second filter parts. Irradiate and decompose And release Control for controlling adsorption and decomposition time of solvent vapor in the first and second filter sections by selectively opening and closing the first and second ultraviolet irradiation means and the first and second on-off valves. Means.
[0015]
Claim 6 invention An image carrier that carries an electrostatic latent image When, A developing means for supplying and developing a liquid developer comprising developer particles and a solvent to the electrostatic latent image carried on the image carrier, and transferring the developer image developed by the developing means and removing the solvent. Intermediate transfer body to be evaporated, transfer means for transferring the developer image transferred to the intermediate transfer body onto a transfer material, suction means for sucking the evaporated solvent, and solvent vapor sucked by the suction means Cooling means for cooling the first, second flow paths for flowing the solvent vapor cooled by the cooling means, first and second on-off valves for opening and closing the first and second flow paths, UV light is applied to the first and second filter parts, which are provided on the exhaust side of the first and second flow paths, respectively, and adsorb the solvent vapor, and the solvent vapor adsorbed to the first and second filter parts. Irradiate and decompose And release First and second ultraviolet irradiation means, a detection sensor for detecting the concentration of the solvent vapor that has passed through the first and second filters, and the first and second in accordance with the detection concentration of the detection sensor Control means for controlling adsorption and decomposition time of the solvent vapor in the first and second filter parts by selectively opening and closing the on-off valve.
[0016]
Claim 7 invention An image carrier that carries an electrostatic latent image When, A developing means for supplying and developing a liquid developer comprising developer particles and a solvent to the electrostatic latent image carried on the image carrier, and transferring the developer image developed by the developing means and removing the solvent. Intermediate transfer body to be evaporated, transfer means for transferring the developer image transferred to the intermediate transfer body onto a transfer material, suction means for sucking the evaporated solvent, and solvent vapor sucked by the suction means Cooling means for cooling the first, second flow paths for flowing the solvent vapor cooled by the cooling means, first and second on-off valves for opening and closing the first and second flow paths, UV light is applied to the first and second filter parts, which are provided on the exhaust side of the first and second flow paths, respectively, and adsorb the solvent vapor, and the solvent vapor adsorbed to the first and second filter parts. Irradiate and decompose And release First and second ultraviolet irradiation means, first and second shutters for opening and closing the exhaust side of the first and second filters, the first and second on-off valves, and the first and second valves Control means for controlling the adsorption and decomposition time of the solvent vapor in the first and second filter sections by selectively opening and closing the shutter.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to an embodiment shown in the drawings.
[0018]
FIG. 1 schematically shows an image forming unit of a wet electrophotographic recording apparatus.
[0019]
In FIG. 1, reference numeral 1 denotes a photosensitive drum as a rotatable latent image holding member in which an organic or amorphous silicon photosensitive layer is formed on a conductive substrate. A peripheral portion of the photosensitive drum 1 is sequentially provided in the direction of rotation with a well-known corona charger or first to fourth chargers 2a to 2d of a scorotron, and first to first laser beams irradiated with image modulation. Fourth laser exposure units 3a to 3d and first to fourth developing devices 4a to 4d for supplying a liquid developer composed of toner and solvent which are developer particles of different colors are arranged.
[0020]
The intermediate transfer medium 6 is in rolling contact with the upper surface portion of the photosensitive drum 1, and the backup roller 8 is in pressure contact with the upper surface portion of the intermediate transfer medium 6. The intermediate transfer body 6 and the backup roller 8 constitute a transfer device 5, and the sheet is conveyed between the intermediate transfer medium 6 and the backup roller 8.
[0021]
At the time of image formation, the peripheral surface of the photosensitive drum 1 is uniformly charged by the first charger 2a, and then exposed by being irradiated with the laser beam image-modulated by the first laser exposure unit 3a. An electrostatic latent image is formed. Thereafter, the liquid developer is supplied from the first developing device 4a, and the electrostatic latent image is visualized and the surplus developer is squeezed. The liquid developer (or toner) adhering to the electrostatic latent image reaches the transfer step as it is, and may be transferred onto the paper by the transfer device 5, but here, the second charger 2b and the second laser exposure are continued here. A second electrostatic latent image is formed by the unit 3b, and a second developer having a different color from the liquid developer stored in the first developing device 4a is supplied from the second developing device 4b. Develop. Therefore, after the second development, a two-color toner image is formed on the photosensitive drum 1. Similarly, third and fourth developments are performed, and a full-color toner image is formed on the photosensitive drum 1. The toner image is transferred to a sheet by the transfer device 5, but is transferred to a transfer medium (sheet) 10 via an intermediate transfer medium 6 as illustrated in FIG. 1. As a result, the quality of the image is less affected by the transfer medium than when the image is directly transferred onto the paper. In the transfer from the photosensitive drum 1 to the intermediate transfer medium 6 and the transfer from the intermediate transfer medium 6 to the paper 10, either transfer by electric field or transfer by pressure (and heat) can be used.
[0022]
In this embodiment, the sheet is pressed against the intermediate transfer medium 6 by the backup roller 8 in order to bring the intermediate transfer medium 6 and the sheet 10 into close contact with each other. In general, many liquid developers can be fixed on paper at room temperature, but the backup roller 8 is heated by a heater 9 to improve transferability and fixability, and the solvent is evaporated as described later. . Such an image forming process is disclosed in, for example, US Pat. No. 5,570,173, and is a conventionally known process.
[0023]
FIG. 2 shows a solvent vapor recovery unit of the wet electrophotographic recording apparatus.
[0024]
When the developing operation is performed on the photosensitive drum 1 as described above, a visible image is formed by the toner (charged color material particles having a particle size of 0.1 to 0.5 μm) in the developer, and the development is performed. A layer of a solvent (a non-polar hydrocarbon having a low conductivity such as trade name Isopar or Norper) is also formed in the liquid. If this solvent layer is not removed before being transferred to the paper 10, it will adhere to the paper 10 and be released outside the machine.
[0025]
Therefore, since the intermediate transfer medium 6 is heated and heated by the heater 9 in order to promote the transfer, the heat is used to evaporate the solvent on the intermediate transfer medium 6. For this reason, it is not necessary to provide another heating source only for evaporating the solvent, and power consumption does not increase. Since the solvent vapor is generated in the vicinity of the intermediate transfer medium 6, the casing 11 is provided at the position, and the vapor generated in the casing 11 is guided to the cooling unit 13 through a path such as a resin tube together with air. The power for sucking the solvent vapor to the cooling unit 13 is, for example, by a blower or a vacuum pump 14 as suction means provided downstream from the cooling unit 13. When the solvent vapor led to the cooling unit 13 is cooled, the saturated vapor pressure decreases, and the excess solvent liquefies and flows down to the solvent recovery container 15. At this time, water vapor in the air inside the cooling unit 13 is also cooled and stored in the solvent recovery container 15 as water. Here, the intermediate transfer medium 6 is heated to 50 to 100 ° C. to evaporate the solvent, and cooled to 0 to 15 ° C. in the cooling unit to be liquefied. However, even if the solvent vapor is cooled to 0 ° C., the saturated vapor pressure of the solvent is not zero, so that a certain amount of solvent vapor is released from the exhaust port of the pump 14. This is adsorbed and decomposed by a plurality of (first and second) filter portions 16a and 16b provided further downstream, and air containing no solvent vapor is discharged outside the apparatus.
[0026]
Next, the filter units 16a and 16b will be described.
[0027]
The filter parts 16a and 16b are obtained by supporting titanium oxide powder on inorganic fibers and organic fibers. When air containing solvent vapor passes through the fiber, the solvent vapor adheres to the surface of the fiber, that is, titanium oxide, and when irradiated with ultraviolet rays in this state, the substance that contacts the surface with the oxidizing power of titanium oxide, this In some cases, hydrocarbons are oxidatively decomposed to carbon dioxide and water. For this reason, it does not have a lifetime like a general adsorption filter and can be used almost permanently. The decomposition function due to titanium oxide optical contact occurs only when UV light is received and contacted with a substance. Therefore, in order for the filter parts 16a and 16b to have high decomposition performance, the surface area of the filter parts 16a and 16b is increased and the surface is exposed to UV light. It is necessary to irradiate the filter part 16a, 16b frequently with the substance.
[0028]
3 and 4 show the decomposition of the solvent vapor by the filter parts 16a and 16b.
[0029]
The solvent vapor 20 contacts and adheres to the fiber 21 surfaces of the filter portions 16a and 16b. At the same time, ultraviolet rays 22 are irradiated, and the solvent becomes water and carbon dioxide, which are the final decomposition substances 23, and is released into the air.
[0030]
Here, the surface area of the filter portions 16a and 16b is increased when the fibers 21 are woven in dozens, but since the ultraviolet rays 22 do not reach the inside, the decomposition action does not occur. For this reason, the fiber 21 must have a thickness (overlap number) that allows the ultraviolet rays 22 to reach the inside.
[0031]
In addition, if there is a region where the solvent vapor 20 is in intensive contact, adhesion occurs faster than the solvent is decomposed. In such a state, excess solvent on the surface of the filter fiber is detached from the fiber again. Leaks out of the machine. In order to prevent this from occurring, it is also necessary to allow the solvent vapor to permeate uniformly over the entire surface of the filter portions 16a and 16b.
[0032]
FIG. 5 shows the configuration from the pump 14 to the filter parts 16a and 16b in detail.
[0033]
The solvent vapor generated in the vicinity of the transfer roller passes through the cooling section 13 from the casing 11 and flows into the downstream filter sections 16a and 16b by the pump 14, and the air that has passed through the filters 30a and 30b is discharged outside the apparatus. In this step, the solvent vapor that has not been liquefied by the cooling unit 13 adheres to the filters 30a and 30b. Ultraviolet lamps 31a and 31b are provided inside the casings 29a and 29b of the filters 30a and 30b so as to irradiate the surfaces of the filters 31a and 31b. In addition, electromagnetic valves 33a and 33b connected to the control unit 32 are provided in the middle of the path from the pump 14 to the filter units 16a and 16b, respectively, so that the solvent vapor flowing through the filter units 16a and 16b passes and is blocked. To control. In this embodiment, there are two paths, but three or more paths may be used.
[0034]
Next, the printing operation and the adsorption / decomposition operation of the solvent vapor in the filter units 16a and 16b will be described with reference to FIG.
[0035]
First, the first electromagnetic valve 33a is opened to turn on the first ultraviolet lamp 31a, and the second electromagnetic valve 33b is closed to turn off the second ultraviolet lamp 31b (step S1). When the printing operation starts, the organic solvent which is the carrier liquid in the developer heated by the intermediate transfer roller 6 is evaporated and becomes vapor. The steam passes through the cooling unit 13 by the suction force of the pump 14, passes through the first filter 30a where the first electromagnetic valve 33a is open, and is adsorbed. The adsorbed solvent vapor is decomposed into water and carbon dioxide when the first filter portion 16a is irradiated with ultraviolet rays from the first ultraviolet lamp 31a. Even when the printing operation is finished, the ultraviolet irradiation of the first filter portion 16a is continued. This is because the adsorption capacity (the amount of solvent adhering to the filter 30a per unit time) of the filter 30a is higher than the decomposition capacity (the amount of solvent decomposed per unit time). Next, it is determined whether or not continuous printing is performed (step S2). In the case of continuous printing, the second electromagnetic valve 33b is opened together with the first electromagnetic valve 33a (step S3), and the second filter unit 16b. Also flow solvent vapor. At the same time, the first ultraviolet lamp 31 and the second ultraviolet lamp 31b of the second filter section 16b are also irradiated, and both the first and second filter sections 16a and 16b adsorb and decompose the solvent vapor. To do.
[0036]
In ordinary copying machines and printers, the frequency of continuous use is low, and there is a considerable time during which printing is not performed. In such a state, the generation amount of the solvent vapor is small, and the adsorption and decomposition treatment of the solvent vapor can be performed without using all of the plurality of filter parts 16a and 16b. Accordingly, it is not necessary to turn on an extra ultraviolet lamp, power can be saved, and deterioration of the filter and the case due to ultraviolet rays can be prevented (for example, there is no electromagnetic valve and the two filter portions 16a and 16b are not provided). If the solvent vapor flows into the lamp, all the ultraviolet lamps 31a and 31b must always be turned on).
[0037]
FIG. 7 shows another example of the printing operation described above and the adsorption and decomposition of the solvent vapor in the filter sections 16a and 16b.
[0038]
The route for generating and collecting the solvent vapor is the same as that shown in FIG.
[0039]
First, the first electromagnetic valve 33a is opened to turn on the first ultraviolet lamp 31a, and the second electromagnetic valve 33b is closed to turn off the second ultraviolet lamp 31b (step S11). When the printing operation starts, the organic solvent in the developer heated by the intermediate transfer roller 6 evaporates and becomes vapor. The steam passes through the cooling unit 13 by the pump 14, passes through the first filter unit 30a where the first electromagnetic valve 33a is open, and is adsorbed. The adsorbed solvent vapor is decomposed into water and carbon dioxide when irradiated with the ultraviolet rays emitted from the first ultraviolet lamp 31a. Even when the printing operation is finished, the ultraviolet irradiation of the first filter portion 16a is continued. Since the amount of solvent vapor generated is determined by the number of printed sheets, irradiation is terminated when ultraviolet rays are irradiated for a time period to decompose the generated solvent. Next, it is determined whether or not there is a solvent in the second filter unit 30b (step 12). If there is solvent vapor, ultraviolet light is emitted from the second ultraviolet lamp 31b (step 13), and if there is no solvent vapor, It is determined whether or not a certain number of sheets or continuous printing is performed (step 14). If it is not a fixed number of sheets or continuous printing, the process returns to step S11, and if it is a fixed number of sheets or continuous printing (for example, when a counter for measuring the number of printed sheets in the apparatus reaches a predetermined value within a predetermined time), 33a is closed to turn on the first ultraviolet lamp 31a, and the second electromagnetic valve 33b is opened to turn on the second ultraviolet lamp 31b (step S15). Thereby, only the decomposition of the solvent is performed in the first filter unit 16a, and the adsorption and decomposition are performed in the second filter unit 16b. Here, when continuous printing is performed, that is, when the amount of solvent vapor generated per unit time is the largest, the adsorption of the second filter unit 16b is saturated until the decomposition is completed in the first filter unit 16a. The areas of the filters 30a and 30b, the amount of ultraviolet light, and the flow rate of steam are set so that they do not occur.
[0040]
If the adsorption capacity of the filters 30a and 30b is higher than the decomposition capacity, the adsorption is significantly higher than that of the decomposition, and solvent vapor is generated again from the outermost periphery of the solvent adsorbed on the filters 30a and 30b, or the solvent is filtered. It may occur that it passes without being adsorbed by 30b. By taking a longer time for decomposition than the time for adsorbing the solvent as in this method, the next filter is used when the adsorption becomes saturated, so that the solvent does not leak.
[0041]
As described above, after the solvent is decomposed in the first filter portion 16a, it is determined whether or not the first filter 16a has solvent vapor (step S16). Irradiation is performed (step S17), and if there is no solvent vapor, it is determined whether or not a certain number of sheets or continuous printing is performed (step 18). If it is not a fixed number or continuous printing, the process returns to step S15, and if it is a fixed number or continuous printing, the process returns to step S11.
[0042]
FIG. 8 shows a second embodiment of the present invention.
[0043]
In addition, the same part as the part shown in the said embodiment is attached | subjected and demonstrated.
[0044]
In this embodiment, solvent vapor concentration sensors 40a and 40b are attached downstream of the first and second filters 30a and 30b of the first and second filter sections 16a and 16b. The concentration sensors 40a and 40b use sintered n-type semiconductor gas sensors mainly composed of tin oxide (= SnO2). This utilizes the phenomenon that the electrical resistance value decreases when the reducing gas is adsorbed to the sensors 40a and 40b. Here, the route of the solvent vapor is switched by the outputs of the respective concentration sensors 40a and 40b. For example, before the printing operation starts, the first electromagnetic valve 33a is opened, the second electromagnetic valve 33b is closed, and the first ultraviolet lamp 31a of the first filter portion 16a is irradiated. The solvent vapor flows to the first filter portion 16a, and is adsorbed and decomposed.
[0045]
When the frequency of printing operation is low and the amount of solvent vapor generated is small, the first filter unit 16a alone can sufficiently process, but when the amount generated increases, the solvent vapor passes through the first filter unit 16a. In such a situation, the first concentration sensor 40a provided downstream of the first filter portion 16a detects that the amount of solvent vapor passing through the first filter portion 16a has increased, and receives this. The second electromagnetic valve 33b is also opened and irradiated with ultraviolet rays, so that the second filter portion 16b is also adsorbed and decomposed. Also in this case, as described above, when the generation amount is small, the adsorption and decomposition processes are performed by using some of the plurality of filter units, so that no extra ultraviolet lamp is irradiated, thus saving power and long life. Can be achieved.
[0046]
Further, by detecting that the amount of generated steam is large based on the output of the concentration sensor 40, the same effect as that of the above-described embodiment can be obtained by switching the filter as described with reference to FIG.
[0047]
FIG. 9 shows a third embodiment of the present invention.
[0048]
In addition, the same part as the part shown in the said embodiment is attached | subjected and demonstrated.
[0049]
The route for generating and collecting the solvent vapor is the same as that shown in FIG. 5, and the printing operation and the adsorption / decomposition operation of the solvent vapor by the filter are the same as those shown in FIG.
[0050]
First, before the printing operation starts, the first electromagnetic valve 33a is opened and the second electromagnetic valve 33b is closed. The generated vapor passes through the first filter 30a and is adsorbed, and at the same time, it is decomposed into water and carbon dioxide by irradiating ultraviolet rays from the first ultraviolet lamp 31a of the first filter portion 16a.
[0051]
Next, when a predetermined number of sheets are printed continuously or within a predetermined time, for example, a counter for measuring the number of printed sheets in the apparatus reaches a predetermined value within a predetermined time, or a sensor downstream of a filter (not shown) When it is detected that the concentration of the solvent vapor to be discharged has reached a predetermined value, the first electromagnetic valve 33a is closed and the second electromagnetic valve 33b is opened, and at the same time, the second electromagnetic valve 33b inside the second filter portion 16b is opened. The second ultraviolet lamp 31b is turned on.
[0052]
At this time, the first shutter 50a at the outlet of the first filter portion 16a closes the air exhaust port by a driving device (not shown), and the first filter portion 16a is sealed. For this reason, when only the decomposition operation of the solvent vapor is performed in the first filter portion 16a, there is no flow of air, and the solvent adsorbed on the filter 16a does not escape from the filter 16a and leak.
[0053]
【The invention's effect】
As described above, in the present invention, the solvent vapor released from the cooling means is adsorbed by the filter unit, and the adsorbed solvent vapor is decomposed by irradiating with ultraviolet rays. It can be used continuously for a long time without being adsorbed, and the replacement work of the filter portion can be reduced.
[0054]
In addition, in order to control the ultraviolet irradiation by the first and second ultraviolet irradiation means according to the amount of solvent vapor generated and to control the opening and closing of the first and second on-off valves, when the amount of solvent vapor generated is small, Solvent vapor can be sent to one of the first and second filter sections to be adsorbed and decomposed, and power can be saved, and deterioration of the filter can be prevented.
[0055]
Further, the time for adsorbing the solvent vapor in the filter unit to control the adsorption and decomposition time of the solvent vapor in the first and second filter units by selectively opening and closing the first and second on-off valves. The time for decomposition can be made longer, and solvent vapor is not released from the filter section.
[0056]
In addition, since the first and second shutters that open and close the exhaust side of the first and second filter parts are provided, the release of solvent vapor from the filter part can be more reliably prevented.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram illustrating an image forming unit of a wet electrophotographic apparatus according to an embodiment of the present invention.
FIG. 2 is a configuration diagram showing a solvent vapor recovery unit.
FIG. 3 is a view showing an adsorption operation of a solvent vapor by a filter.
FIG. 4 is a view showing the decomposition operation of the solvent vapor of the filter.
FIG. 5 is a diagram showing a filter section and a route of solvent vapor.
FIG. 6 is a flowchart showing a printing operation and a solvent vapor recovery operation.
FIG. 7 is a flowchart showing a printing operation and another recovery operation of solvent vapor.
FIG. 8 is a diagram showing a filter unit and a steam path according to a second embodiment of the present invention.
FIG. 9 is a diagram showing a filter unit and a steam path according to a third embodiment of the present invention.
[Explanation of symbols]
1 ... photosensitive drum (latent image carrier)
5 ... Transfer device
6 ... Intermediate transfer member (transfer means)
8 ... Backup roller (transfer means)
10 ... paper (transfer medium)
13 ... Cooling section
14 ... Pump (suction means)
16a ... 1st filter part
16b ... 2nd filter part
30a ... first filter
30b ... second filter
31a ... 1st ultraviolet irradiation means (1st ultraviolet lamp)
31b ... second ultraviolet irradiation means (second ultraviolet lamp)
32. Control means
33a ... 1st electromagnetic valve (1st on-off valve)
33b ... second electromagnetic valve (second on-off valve)
40a ... first concentration sensor (detection sensor)
40b ... Second concentration sensor (detection sensor)
50a ... first shutter
50b ... second shutter

Claims

An image carrier for carrying an electrostatic latent image;
Developing means for developing the electrostatic latent image carried on the image carrier by supplying a liquid developer comprising developer particles and a solvent;
An intermediate transfer member for transferring the developer image developed by the developing means and evaporating the solvent;
Transfer means for transferring the developer image transferred to the intermediate transfer member to a transfer material;
A suction means for sucking the evaporated solvent;
A cooling means for cooling the solvent vapor sucked by the suction means;
A filter that adsorbs the solvent vapor released from the cooling means;
UV irradiation means for radiating and decomposing the solvent vapor adsorbed on the filter unit by UV irradiation , and releasing it ;
An image forming apparatus comprising:

An image carrier for carrying an electrostatic latent image ;
Developing means for developing the electrostatic latent image carried on the image carrier by supplying a liquid developer comprising developer particles and a solvent;
An intermediate transfer member for transferring the developer image developed by the developing means and evaporating the solvent;
Transfer means for transferring the developer image transferred to the intermediate transfer member to a transfer material;
A suction means for sucking the evaporated solvent;
A cooling means for cooling the solvent vapor sucked by the suction means;
It adsorbs the solvent vapor released from this cooling means, and a filter part in which titanium oxide powder is supported on inorganic and organic fibers,
UV irradiation means for radiating and decomposing the solvent vapor adsorbed on the filter unit by UV irradiation , and releasing it ;
An image forming apparatus comprising:

An image carrier for carrying an electrostatic latent image ;
Developing means for developing the electrostatic latent image carried on the image carrier by supplying a liquid developer comprising developer particles and a solvent;
An intermediate transfer member for transferring the developer image developed by the developing means and evaporating the solvent;
Transfer means for transferring the developer image transferred to the intermediate transfer member to a transfer material;
Suction means for sucking the evaporated solvent;
Cooling means for cooling the solvent vapor sucked by the suction means;
First and second flow paths for flowing the solvent vapor cooled by the cooling means;
First and second on-off valves for opening and closing these first and second flow paths;
First and second filters provided on the exhaust side of the first and second flow paths, respectively, for adsorbing solvent vapor;
First and second ultraviolet irradiation means for irradiating the solvent vapor adsorbed on the first and second filters with ultraviolet rays to decompose and release them ;
Control means for controlling the opening and closing of the first and second on-off valves and the ultraviolet irradiation by the first and second ultraviolet irradiation means according to the amount of the solvent vapor generated;
An image forming apparatus comprising:

An image carrier for carrying an electrostatic latent image ;
Developing means for developing the electrostatic latent image carried on the image carrier by supplying a liquid developer comprising developer particles and a solvent;
An intermediate transfer member for transferring the developer image developed by the developing means and evaporating the solvent;
Transfer means for transferring the developer image transferred to the intermediate transfer member to a transfer material;
Suction means for sucking the evaporated solvent;
Cooling means for cooling the solvent vapor sucked by the suction means;
First and second flow paths for flowing the solvent vapor cooled by the cooling means;
First and second on-off valves for opening and closing these first and second flow paths;
First and second filter portions that are respectively provided on the exhaust side of the first and second flow paths and adsorb solvent vapor;
First and second ultraviolet irradiation means for irradiating and decomposing the solvent vapor adsorbed on the first and second filter portions by ultraviolet rays , and releasing them ;
A detection sensor for detecting the concentration of solvent vapor that has passed through the first and second filters;
Control means for controlling the opening and closing of the first and second on-off valves and the ultraviolet irradiation by the first and second ultraviolet irradiation means in accordance with the detected concentration of the detection sensor;
An image forming apparatus comprising:

An image carrier for carrying an electrostatic latent image ;
Developing means for developing the electrostatic latent image carried on the image carrier by supplying a liquid developer comprising developer particles and a solvent;
An intermediate transfer member for transferring the developer image developed by the developing means and evaporating the solvent;
Transfer means for transferring the developer image transferred to the intermediate transfer member to a transfer material;
Suction means for sucking the evaporated solvent;
Cooling means for cooling the solvent vapor sucked by the suction means;
First and second flow paths for flowing the solvent vapor cooled by the cooling means;
First and second on-off valves for opening and closing these first and second flow paths;
First and second filter portions that are respectively provided on the exhaust side of the first and second flow paths and adsorb solvent vapor;
First and second ultraviolet irradiation means for irradiating and decomposing the solvent vapor adsorbed on the first and second filter portions by ultraviolet rays , and releasing them ;
Control means for controlling adsorption and decomposition time of the solvent vapor in the first and second filter parts by selectively opening and closing the first and second on-off valves;
An image forming apparatus comprising:

An image carrier for carrying an electrostatic latent image ;
Developing means for developing the electrostatic latent image carried on the image carrier by supplying a liquid developer comprising developer particles and a solvent;
An intermediate transfer member for transferring the developer image developed by the developing means and evaporating the solvent;
Transfer means for transferring the developer image transferred to the intermediate transfer member to a transfer material;
A suction means for sucking the evaporated solvent;
Cooling means for cooling the solvent vapor sucked by the suction means;
First and second flow paths for flowing the solvent vapor cooled by the cooling means;
First and second on-off valves for opening and closing these first and second flow paths;
First and second filter portions that are respectively provided on the exhaust side of the first and second flow paths and adsorb solvent vapor;
First and second ultraviolet irradiation means for irradiating and decomposing the solvent vapor adsorbed on the first and second filter portions by ultraviolet rays , and releasing them ;
A detection sensor for detecting the concentration of solvent vapor that has passed through the first and second filters;
Control means for controlling the adsorption and decomposition time of the solvent vapor in the first and second filter parts by selectively opening and closing the first and second on-off valves according to the detected concentration of the detection sensor. When,
An image forming apparatus comprising:

An image carrier for carrying an electrostatic latent image ;
Developing means for developing the electrostatic latent image carried on the image carrier by supplying a liquid developer comprising developer particles and a solvent;
An intermediate transfer member for transferring the developer image developed by the developing means and evaporating the solvent;
Transfer means for transferring the developer image transferred to the intermediate transfer member to a transfer material;
A suction means for sucking the evaporated solvent;
Cooling means for cooling the solvent vapor sucked by the suction means;
First and second flow paths for flowing the solvent vapor cooled by the cooling means;
First and second on-off valves for opening and closing these first and second flow paths;
First and second filter portions that are respectively provided on the exhaust side of the first and second flow paths and adsorb solvent vapor;
First and second ultraviolet irradiation means for irradiating and decomposing the solvent vapor adsorbed on the first and second filter portions by ultraviolet rays , and releasing them ;
First and second shutters for opening and closing exhaust sides of the first and second filters;
Control means for controlling adsorption and decomposition time of the solvent vapor in the first and second filter sections by selectively opening and closing the first and second on-off valves and the first and second shutters; ,
An image forming apparatus comprising: