JP4040796B2

JP4040796B2 - Image forming apparatus

Info

Publication number: JP4040796B2
Application number: JP17835999A
Authority: JP
Inventors: 正士廣木
Original assignee: Toshiba Corp; Toshiba TEC Corp
Current assignee: Toshiba Corp; Toshiba TEC Corp
Priority date: 1999-06-24
Filing date: 1999-06-24
Publication date: 2008-01-30
Anticipated expiration: 2019-06-24
Also published as: JP2001005355A

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。即ち、サブミクロ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上に印刷（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、溶媒による環境問題があった。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、用紙へ転写される。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５，１６６，７４３、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（および熱）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。これに対し、特開平４８−８３８３８号では、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こめておき、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。
【０００６】
【発明が解決しようとする課題】
しかし、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、湿式電子写真方式の長所である省エネルギが実現できなくなってしまう。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捕獲するが、同時に通過する水蒸気も吸着してしまい吸着性能が短時間しか持続せず、長期間連続使用しうることが困難で、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課題がある。
【０００７】
本発明は上記実情に鑑みなされたもので、フィルタの長期間連続使用を可能とするとともに、吸着した溶媒蒸気の分解性能に優れる画像形成装置を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明は上記課題を解決するため、請求項１記載のものは、潜像保持体上に静電潜像を形成する潜像形成手段と、
この潜像形成手段により形成された静電潜像に溶媒を含む現像剤を供給して可視像化する現像手段と、
この現像手段により可視像化された可視像を一旦中間転写体に転写した後、被転写体上に転写する転写手段と、
前記中間転写体上の可視像を加熱する加熱手段と、
この加熱手段の加熱により蒸発した可視像中の溶媒蒸気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し、液化させて回収する回収手段と、
この回収手段で液化されずに前記吸引手段から排気される溶媒蒸気を吸着するフィルタと、
このフィルタを移動させる駆動手段と、
この駆動手段により移動されてくるフイルタに吸着されている溶媒蒸気に紫外線を照射して分解する紫外線照射手段と、
を具備する。
【０００９】
請求項２記載のものは、潜像保持体上に静電潜像を形成する潜像形成手段と、この潜像形成手段により形成された静電潜像に溶媒を含む現像剤を供給して可視像化する現像手段と、
この現像手段により可視像化された可視像を一旦中間転写体に転写した後、被転写体上に転写する転写手段と、
前記中間転写体上の可視像を加熱する加熱手段と、
この加熱手段の加熱により蒸発した可視像中の溶媒蒸気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し、液化させて回収する回収手段と、
この回収手段で液化されずに前記吸引手段から排気される溶媒蒸気を吸着するフィルタと、
このフィルタを前記溶媒蒸気を吸着する第１の位置とこの第１の位置と異なる第２の位置との間で移動させる駆動手段と、
この駆動手段により第２の位置に移動されてくるフイルタに吸着されている溶媒蒸気に紫外線を照射して分解する紫外線照射手段と、
を具備する。
【００１０】
請求項３記載のものは、潜像保持体上に静電潜像を形成する潜像形成手段と、
この潜像形成手段により形成された静電潜像に溶媒を含む現像剤を供給して可視像化する現像手段と、
この現像手段により可視像化された可視像を一旦中間転写体に転写した後、被転写体上に転写する転写手段と、
前記中間転写体上の可視像を加熱する加熱手段と、
この加熱手段の加熱により蒸発した可視像中の溶媒蒸気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し、液化させて回収する回収手段と、
この回収手段で液化されずに前記吸引手段から排気される溶媒蒸気を吸着するフィルタと、
このフィルタの両端部を巻取軸に巻回し、前記巻取軸を回転させることにより前記溶媒蒸気を吸着する第１の位置とこの第１の位置と異なる第２の位置との間で移動させる駆動手段と、
この駆動手段により第２の位置に移動されてくるフイルタに吸着されている溶媒蒸気に紫外線を照射して分解する紫外線照射手段と、
を具備する。
【００１１】
請求項４記載のものは、潜像保持体上に静電潜像を形成する潜像形成手段と、
この潜像形成手段により形成された静電潜像に溶媒を含む現像剤を供給して可視像化する現像手段と、
この現像手段により可視像化された可視像を一旦中間転写体に転写した後、被転写体上に転写する転写手段と、
前記中間転写体上の可視像を加熱する加熱手段と、
この加熱手段の加熱により蒸発した可視像中の溶媒蒸気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し、液化させて回収する回収手段と、
この回収手段で液化されずに前記吸引手段から排気される溶媒蒸気を第１の部位とこの第１の部位と異なる第２の部位に通過させてそれぞれ吸着するフィルタと、
このフィルタを移動させる駆動手段と、
この駆動手段により移動されてくるフイルタに吸着されている溶媒蒸気に紫外線を照射して分解する紫外線照射手段と、
を具備する。
【００１２】
請求項５記載のものは、潜像保持体上に静電潜像を形成する潜像形成手段と、この潜像形成手段により形成された静電潜像に溶媒を含む現像剤を供給して可視像化する現像手段と、
この現像手段により可視像化された可視像を一旦中間転写体に転写した後、被転写体上に転写する転写手段と、
前記中間転写体上の可視像を加熱する加熱手段と、
この加熱手段の加熱により蒸発した可視像中の溶媒蒸気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し、液化させて回収する回収手段と、
この回収手段で液化されずに前記吸引手段から排気される溶媒蒸気を第１の部位とこの第１の部位と離間対向する第２の部位に通過させてそれぞれ吸着するフィルタと、
このフィルタを無端走行させる駆動手段と、
この駆動手段により走行されてくるフイルタに吸着されている溶媒蒸気に紫外線を照射して分解する紫外線照射手段と、
を具備する。
【００１３】
【発明の実施の形態】
以下、本発明を図面に示す実施の形態を詳細して説明する。
【００１４】
図１は本発明の一実施の形態である湿式電子写真記録装置の画像形成部を示すものである。
【００１５】
図中１は矢印方向に回転自在に設けられた潜像保持体で、この潜像保持体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設けた感光体ドラムである。この潜像保持体１の周囲部にはその回転方向に亘って、第１乃至第４の周知のコロナ帯電器（もしくはスコロトロン帯電器）２ａ〜２ｄ、第１乃至第４の露光部（潜像形成手段）３ａ〜３ｄ及び第１乃至第４の現像装置４ａ〜４ｄ、さらに、転写装置５が配設されている。
【００１６】
帯電器２ａ〜２ｄは潜像保持体１の表面を均一に帯電するものである。
【００１７】
露光部３ａ〜３ｄは画像変調されたレーザビームにより潜像保持体１の表面を露光し、表面に静電潜像を形成するものである。
【００１８】
現像装置４ａ〜４ｄは液体現像剤を収納し、静電潜像の可視像化と余剰現像剤のスクイーズを行うものである。
【００１９】
転写装置５は可視像を被転写体としての用紙１０に転写するもので、中間転写媒体６とバックアップローラ８を有し、中間転写媒体６にはヒータ９が内蔵されている。
【００２０】
画像形成時には、潜像保持体１の表面が帯電器２ａによって均一に帯電された後、露光部３ａにより画像変調されたレーザビームによる露光を受け、表面に静電潜像が形成される。しかる後に、液体現像剤を収納する現像装置４ａによって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１０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の現像剤を収納する第２の現像装置４ｂによってこれを現像する。従って、第２現像の後には、潜像保持体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、潜像保持体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１０に転写されるが、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１０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。潜像保持体１から中間転写媒体６への転写、および中間転写媒体６から被転写媒体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。本図では、中間転写媒体６と用紙１０を密着させるため、バックアップローラ８で用紙１０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、中間転写媒体６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。
【００２１】
図２は中間転写媒体６で発生する溶媒蒸気を回収する溶媒蒸気回収部２０Ａを示すものである。
【００２２】
潜像保持体１上で現像動作が行なわれると、現像液中のトナー（粒径０．１〜５μｍ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（例えば商品名アイソパー、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。
【００２３】
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、消費電力の増加が少ない。
【００２４】
溶媒蒸気は、中間転写媒体６の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、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、吸引手段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フィルタ部１６により捕獲、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。
【００２５】
次に、フィルタ部１６について説明する。
【００２６】
フィルタは無機繊維、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し付着する。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。
【００２７】
酸化チタン光触媒による分解機能は、紫外線を受光し、物質と接触して初めて生じるので、フィルタが高い分解性能を持つにはフィルタの表面積を増やし、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はフィルタによる溶媒蒸気の分解を説明するものである。
【００２９】
溶媒蒸気２０がフィルタの繊維２１の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、フィルタに溶媒蒸気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溶媒の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は溶媒蒸気回収部２０Ａの最終段に設けられているフィルタ部１６を詳細に示すものである。
【００３３】
フィルタ部１６は溶媒蒸気を吸着する表面に酸化チタンが塗布されたフィルタ３０と、ポンプ１４から溶媒蒸気を含んだ空気をフィルタ３０を通過させた後、機外へ導く管路部３１と、フィルタ３０に紫外線を照射する紫外線ランプ３２が並列に並んだ紫外線照射部３３と、紫外線が照射される紫外線照射部３３の間を移動させる機構から構成されている。フィルタ３０は端部を有する帯状で、その両端部をシャフト３４、３５に固定されて、懸架されており、シャフト４，３５が図示しない駆動系により回転することで、両方向に移動される。
【００３４】
次に、フィルタ部１６Ａの動作を説明する。
【００３５】
印刷動作が開始すると、フィルタ３０は管路部３１から紫外線照射部３３へ向かう方向へ移動される。溶媒蒸気はポンプ１４から排気され管路部３１を通り、その中を通過中のフィルタ３０が溶媒蒸気を吸着する。フィルタ３０は吸着した溶媒を保持したまま、紫外線照射部３３の内部に搬送され、紫外線ランプ３２により両面から紫外線が照射される。ここで、酸化作用が生じ、溶媒である炭化水素が二酸化炭素と水に分解される。フィルタ３０がシャフト３４に巻き終わると、吸着、分解動作が行なわれている場合の搬送速度より高速でシャフト３５に巻き戻され、溶媒蒸気の吸着、分解を繰り返す。このようなフィルタ部１６Ａの動作は、印刷動作中はもちろん、印刷動作終了もフィルタ３０に吸着した溶媒が分解し終えるまで行なわれる。このように、フィルタ３０を移動させながら吸着を行なうので、溶媒蒸気がフィルタ３０全面に均一に薄層の状態で付くので、紫外線を照射することで分解を効率的に行なうことができる。
【００３６】
また、この実施の形態では、フィルタ３０は印刷動作中、所定の速度で搬送され、溶媒の吸着、分解動作を繰り返す。本発明に用いる薄い布状のフィルタは溶媒を吸着する面全てに紫外線が照射できるので分解効率が高いが、それでも溶媒の分解速度は吸着速度より遅い。紫外線照射部３３を通過後、次の吸着を行なう位置に搬送されるまでにフィルタ３０上に溶媒が残留していると、繰り返し動作を行なうことで残留溶媒の量が増加し、管路部３１から機外へ蒸気として排出されてしまう。このようなことを防止するために、フィルタ３０に紫外線が照射させる時間が、溶媒を吸着する時間より長くなるように、フィルタ３０が搬送される方向の管路部３１の長さより、紫外線照射部３３の長さが長く設定されている。
【００３７】
図６は本発明の第２の実施の形態であるフィルタ部１６Ｂを示すものである。
【００３８】
この第２の実施の形態では、フィルタ４０を無端の帯状で２本のシャフト３４、３５で懸架し、一方のシャフト３４が図示しない駆動系により回転することでフィルタ４０は矢印方向に無端走行される。
【００３９】
次に、フィルタ部１６Ｂの動作について説明する。
【００４０】
印刷動作が開始すると、フィルタ４０はシャフト３４、３５の回転により矢印方向に一定速度で搬送される。管路部３１で溶媒蒸気の吸着、紫外線照射部３３で分解が行なわれる。
【００４１】
この実施の形態では、溶媒蒸気はフィルタ４０を２回通過する構成になっている。溶媒が紫外線照射部３３で除去されたフィルタ４０は、再び管路部３１に搬送され、溶媒蒸気の吸着、分解を繰り返す。
【００４２】
このように、溶媒蒸気がフィルタ４０を複数回通過することで、フィルタ４０に吸着する機会が多くなり、機外へ放出する蒸気の量を更に減少することができる。
【００４３】
図７は本発明の第３の実施の形態であるフィルタ部１６Ｃを示すものである。
【００４４】
この第３の実施の形態では、上述したと同様に管路部３１で溶媒蒸気を吸着し、紫外線照射部３３で溶媒蒸気を分解する。溶媒である炭化水素は酸化チタンの酸化作用で二酸化炭素と水に分解されるが、水蒸気になれなかった水がフィルタ４０に付着されたまま、再び管路部３１に到達してしまうと、溶媒蒸気がフィルタ４０に吸着しても、フィルタ表面と溶媒蒸気の間に水が介在してしまい、両者が接触しづらくなる。
【００４５】
両者が接触して初めて溶媒が分解されるので、両者が接触しづらい状態では分解効率が低下してしまう。そこで、紫外線照射部３３を通過したフィルタ４０の表面を紫外線照射部３３の出口に除去手段としてのゴムブレード５０を設置し、この設置したゴムブレード５０で擦ることにより、水を除去する。これにより、フィルタ表面が常に露出するので溶媒と接触する機会が多く、分解の効率が高い。
【００４６】
なお、ゴムブレード５０はシャフト３４と対向する位置に配置しても同様な効果が得られる。
【００４７】
【発明の効果】
本発明は以上説明したように、溶媒蒸気をフイルタに吸着させ、このフイルタに吸着された溶媒蒸気に紫外線を照射して分解するから、フィルタの吸着性能を長期間持続できる。従って、フイルタの交換回数を削減でき、交換作業に手間取ることがない。
【００４８】
また、フィルタを移動させながら溶媒蒸気を吸着するため、フィルタの全面に均一的に溶媒蒸気が吸着でき、紫外線照射時における溶媒の分解効率を向上させることができる。
【００４９】
さらに、フィルタに対し、溶媒蒸気を複数回通過させるから、溶媒蒸気の吸着回数を増大させることができ、溶媒蒸気の外部への放出量を減少させることができる。
【００５０】
また、フィルタの溶媒蒸気の吸着時間よりも紫外線照射時を長くするため、確実に溶媒蒸気を分解でき、外部への放出を防止することができる。
【００５１】
また、フィルタの表面に付着した水を除去する除去手段を設けたから、フイルタ表面が水で覆われることなく常に露出する。従って、フィルタが溶媒蒸気と接触する機会が多くなり、分解効率を向上できる。
【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】湿式電子写真装置の溶媒蒸気回収部を概略的に示す図。
【図３】フィルタの溶媒蒸気の吸着と分解動作を説明す図。
【図４】フィルタが吸着した溶媒蒸気の分解動作を説明す図。
【図５】溶媒蒸気回収部のフィルタ部を示す図。
【図６】本発明の第２の実施の形態であるフィルタ部を示す図。
【図７】本発明の第３の実施の形態であるフィルタ部を示す図。
【符号の説明】
１…潜像保持体
４ａ〜４ｄ…現像装置（現像手段）
５…転写装置（転写手段）
６…中間転写媒体
８…バックアップローラ
９…ヒータ（加熱手段）
１０…用紙（被転写媒体）
１３…冷却部（回収手段）
１４…吸引手段（ポンプ）
１５…回収容器（回収手段）
１６Ａ，１６Ｂ，１６Ｃ…フィルタ部
３０、４０…フィルタ
３１…紫外線ランプ（紫外線照射手段）
５０…ゴムブレード（除去手段）[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. That is, it is possible to use a very fine toner of sub-micro size, so that high image quality can be realized, and a sufficient image density can be obtained with a small amount of toner, and it is economical and has the same texture as printing (for example, offset printing). The main advantages of wet electrophotography with respect to the dry method are that the toner can be fixed on the paper at a relatively low temperature and energy can be saved.
[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 the solvent. In the electric field transfer of the liquid developer, the toner as charged particles moves in the solvent by a well-known electrophoretic phenomenon and is transferred onto the paper. 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, 5,166,743, 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 paper, the adhesion of the solvent to the paper 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. On the other hand, in Japanese Patent Laid-Open No. 48-83838, after transferring a visible image onto 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.
[0006]
[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 method, cannot be realized. For this reason, it is usual 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 captures the solvent vapor that passes through the filter, but also adsorbs water vapor that passes at the same time. In other words, the adsorption performance lasts only for a short time, and it is difficult to use continuously for a long period of time, and there is a problem that a user or a serviceman must frequently replace it.
[0007]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming apparatus that enables continuous use of a filter for a long period of time and is excellent in decomposition performance of adsorbed solvent vapor.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a latent image forming means for forming an electrostatic latent image on a latent image holding member,
Developing means for supplying a developer containing a solvent to the electrostatic latent image formed by the latent image forming means to make a visible image;
A transfer means for transferring the visible image visualized by the developing means to the intermediate transfer body once, and then transferring it onto the transfer body;
Heating means for heating the visible image on the intermediate transfer member;
A suction means for sucking the solvent vapor in the visible image evaporated by heating of the heating means;
A recovery means for cooling and liquefying and recovering the solvent vapor sucked by the suction means;
A filter that adsorbs solvent vapor exhausted from the suction means without being liquefied by the recovery means;
Driving means for moving the filter;
Ultraviolet irradiation means for irradiating the solvent vapor adsorbed by the filter moved by the driving means with ultraviolet rays for decomposition;
It comprises.
[0009]
According to a second aspect of the present invention, a latent image forming unit that forms an electrostatic latent image on a latent image holding member, and a developer containing a solvent is supplied to the electrostatic latent image formed by the latent image forming unit. Developing means for visualizing; and
A transfer means for transferring the visible image visualized by the developing means to the intermediate transfer body once, and then transferring it onto the transfer body;
Heating means for heating the visible image on the intermediate transfer member;
A suction means for sucking the solvent vapor in the visible image evaporated by heating of the heating means;
A recovery means for cooling and liquefying and recovering the solvent vapor sucked by the suction means;
A filter that adsorbs solvent vapor exhausted from the suction means without being liquefied by the recovery means;
Drive means for moving the filter between a first position for adsorbing the solvent vapor and a second position different from the first position;
Ultraviolet irradiation means for irradiating the solvent vapor adsorbed on the filter moved to the second position by the driving means with ultraviolet rays for decomposition;
It comprises.
[0010]
Claim 3 is a latent image forming means for forming an electrostatic latent image on a latent image holding member;
Developing means for supplying a developer containing a solvent to the electrostatic latent image formed by the latent image forming means to make a visible image;
A transfer means for transferring the visible image visualized by the developing means to the intermediate transfer body once, and then transferring it onto the transfer body;
Heating means for heating the visible image on the intermediate transfer member;
A suction means for sucking the solvent vapor in the visible image evaporated by heating of the heating means;
A recovery means for cooling and liquefying and recovering the solvent vapor sucked by the suction means;
A filter that adsorbs solvent vapor exhausted from the suction means without being liquefied by the recovery means;
Both ends of the filter are wound around a winding shaft, and the winding shaft is rotated to move between a first position where the solvent vapor is adsorbed and a second position different from the first position. Driving means;
Ultraviolet irradiation means for irradiating the solvent vapor adsorbed on the filter moved to the second position by the driving means with ultraviolet rays for decomposition;
It comprises.
[0011]
Claim 4 is a latent image forming means for forming an electrostatic latent image on a latent image holding member;
Developing means for supplying a developer containing a solvent to the electrostatic latent image formed by the latent image forming means to make a visible image;
A transfer means for transferring the visible image visualized by the developing means to the intermediate transfer body once, and then transferring it onto the transfer body;
Heating means for heating the visible image on the intermediate transfer member;
A suction means for sucking the solvent vapor in the visible image evaporated by heating of the heating means;
A recovery means for cooling and liquefying and recovering the solvent vapor sucked by the suction means;
A filter that adsorbs the solvent vapor exhausted from the suction means without being liquefied by the recovery means through a first part and a second part different from the first part; and
Driving means for moving the filter;
Ultraviolet irradiation means for irradiating the solvent vapor adsorbed by the filter moved by the driving means with ultraviolet rays for decomposition;
It comprises.
[0012]
According to a fifth aspect of the present invention, a latent image forming unit that forms an electrostatic latent image on the latent image holding member, and a developer containing a solvent is supplied to the electrostatic latent image formed by the latent image forming unit. Developing means for visualizing; and
A transfer means for transferring the visible image visualized by the developing means to the intermediate transfer body once, and then transferring it onto the transfer body;
Heating means for heating the visible image on the intermediate transfer member;
A suction means for sucking the solvent vapor in the visible image evaporated by heating of the heating means;
A recovery means for cooling and liquefying and recovering the solvent vapor sucked by the suction means;
A filter that adsorbs the solvent vapor exhausted from the suction means without being liquefied by the recovery means through the first part and the second part spaced apart from the first part;
Drive means for running the filter endlessly;
Ultraviolet irradiation means for irradiating the solvent vapor adsorbed on the filter traveling by the driving means with ultraviolet rays for decomposition;
It comprises.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention shown in the drawings will be described in detail.
[0014]
FIG. 1 shows an image forming unit of a wet electrophotographic recording apparatus according to an embodiment of the present invention.
[0015]
In the figure, reference numeral 1 denotes a latent image holding member provided rotatably in the direction of an arrow. The latent image holding member 1 is a photosensitive drum provided with an organic or amorphous silicon photosensitive layer on a conductive substrate. . First to fourth known corona chargers (or scorotron chargers) 2a to 2d and first to fourth exposure units (latent images) are arranged on the periphery of the latent image holder 1 in the rotation direction. Forming means) 3a to 3d, first to fourth developing devices 4a to 4d, and a transfer device 5 are disposed.
[0016]
The chargers 2a to 2d are for charging the surface of the latent image holding member 1 uniformly.
[0017]
The exposure units 3a to 3d expose the surface of the latent image holding body 1 with an image-modulated laser beam to form an electrostatic latent image on the surface.
[0018]
The developing devices 4a to 4d contain a liquid developer, and visualize the electrostatic latent image and squeeze the excess developer.
[0019]
The transfer device 5 transfers a visible image onto a sheet 10 as a transfer target, and includes an intermediate transfer medium 6 and a backup roller 8, and the intermediate transfer medium 6 includes a heater 9.
[0020]
At the time of image formation, the surface of the latent image holding body 1 is uniformly charged by the charger 2a, and then exposed by a laser beam image-modulated by the exposure unit 3a to form an electrostatic latent image on the surface. After that, the electrostatic latent image is visualized and the excess developer is squeezed by the developing device 4a containing the liquid developer. The liquid developer or toner adhering to the electrostatic latent image may be transferred to the transfer process 5 as it is, and transferred to the paper 10 by the transfer device 5. Here, however, the second charger 2b and the second laser exposure unit continue here. A second electrostatic latent image is formed in 3b and developed by the second developing device 4b containing a second developer having a different color from the liquid developer contained in the first developing device 4a. To do. Therefore, after the second development, a two-color toner image is formed on the latent image holding member 1. Similarly, third and fourth developments are performed, and a full-color toner image is formed on the latent image holding member 1. This toner image is transferred to the paper 10 by the transfer device 5, but is transferred to the transfer medium (paper) 10 via the intermediate transfer medium 6. As a result, the image quality is not affected by the transfer medium as compared with the case where the image is directly transferred to the paper 10. In the transfer from the latent image carrier 1 to the intermediate transfer medium 6 and the transfer from the intermediate transfer medium 6 to the transfer medium 10, either transfer by electric field or transfer by pressure (and heat) is used. I can do it. In this figure, the sheet 10 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. In general, many liquid developers can be fixed on paper at room temperature, but the intermediate transfer medium 6 is heated by a heater 9 to improve transferability and fixability, and the solvent is evaporated as described later. Yes. Such an image forming process is disclosed in, for example, US Pat. No. 5,570,173, and is a conventionally known process.
[0021]
FIG. 2 shows a solvent vapor recovery section 20A that recovers the solvent vapor generated in the intermediate transfer medium 6.
[0022]
When a developing operation is performed on the latent image holding member 1, a visible image is formed by toner (charged color material particles having a particle diameter of 0.1 to 5 μm) in the developer, and a solvent ( For example, a non-polar hydrocarbon layer having a low conductivity such as trade names ISOPAR and NORPER) is also formed. 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.
[0023]
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 the increase in power consumption is small.
[0024]
Since the solvent vapor is generated in the vicinity of the intermediate transfer medium 6, the casing 11 is provided at that 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 by suction means provided downstream from the cooling unit 13, for example, a blower or a vacuum pump 14. 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 suction means 14. This is captured and decomposed by the filter unit 16 provided further downstream, and air that does not contain solvent vapor is released outside the apparatus.
[0025]
Next, the filter unit 16 will be described.
[0026]
The filter is made by supporting titanium oxide powder on inorganic fibers and organic fibers. When air containing solvent vapor passes through the fiber, the solvent vapor contacts and adheres to the fiber surface, that is, titanium oxide. When ultraviolet rays are irradiated in this state, a substance that comes into contact with the surface by the oxidizing power of titanium oxide, in this case, hydrocarbons are oxidatively decomposed into carbon dioxide and water. For this reason, it does not have a lifetime like a general adsorption filter and can be used almost permanently.
[0027]
Since the decomposition function of titanium oxide photocatalyst occurs only when UV light is received and contacted with the substance, the surface area of the filter is increased in order for the filter to have high decomposition performance, and the surface is irradiated with UV light efficiently. It is necessary to contact the filter frequently.
[0028]
3 and 4 illustrate the decomposition of the solvent vapor by the filter.
[0029]
The solvent vapor 20 contacts and adheres to the surface of the fiber 21 of the filter. 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 is increased if the fibers 21 are woven in dozens, but the ultraviolet rays 22 do not reach the inside, so that 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 an area where solvent vapor is in intensive contact with the filter, the solvent will adhere faster than the solvent is decomposed, and in such a state, excess solvent on the surface of the filter fiber will again come from the fiber. Leaving and leaking outside the aircraft. In order to prevent this from happening, it is also necessary to allow the solvent vapor to permeate the entire surface of the filter uniformly.
[0032]
FIG. 5 shows the filter unit 16 provided in the final stage of the solvent vapor recovery unit 20A in detail.
[0033]
The filter unit 16 includes a filter 30 having titanium oxide coated on the surface that adsorbs the solvent vapor, a pipe line unit 31 that guides the air containing the solvent vapor from the pump 14 to the outside after passing through the filter 30, and a filter. 30 includes an ultraviolet irradiation unit 33 in which ultraviolet lamps 32 for irradiating ultraviolet rays are arranged in parallel and a mechanism for moving between the ultraviolet irradiation unit 33 to which ultraviolet rays are irradiated. The filter 30 has a belt-like shape having ends, and both ends thereof are fixed to the shafts 34 and 35 and suspended, and the shafts 4 and 35 are moved in both directions by being rotated by a drive system (not shown).
[0034]
Next, the operation of the filter unit 16A will be described.
[0035]
When the printing operation is started, the filter 30 is moved in a direction from the pipe line part 31 toward the ultraviolet irradiation part 33. The solvent vapor is exhausted from the pump 14, passes through the pipe line portion 31, and the filter 30 passing through it adsorbs the solvent vapor. The filter 30 is transported into the ultraviolet irradiation unit 33 while holding the adsorbed solvent, and is irradiated with ultraviolet rays from both sides by the ultraviolet lamp 32. Here, an oxidizing action occurs, and the hydrocarbon as a solvent is decomposed into carbon dioxide and water. When the filter 30 finishes being wound around the shaft 34, the filter 30 is rewound onto the shaft 35 at a higher speed than the conveying speed when the adsorption and decomposition operations are performed, and the adsorption and decomposition of the solvent vapor are repeated. Such an operation of the filter unit 16A is performed not only during the printing operation but also at the end of the printing operation until the solvent adsorbed on the filter 30 is completely decomposed. Since the adsorption is performed while moving the filter 30 in this way, the solvent vapor is uniformly attached to the entire surface of the filter 30 in a thin layer state, so that the decomposition can be efficiently performed by irradiating with ultraviolet rays.
[0036]
In this embodiment, the filter 30 is transported at a predetermined speed during the printing operation, and repeats the solvent adsorption and decomposition operations. The thin cloth filter used in the present invention has high decomposition efficiency because it can irradiate all surfaces adsorbing the solvent with ultraviolet rays, but the solvent decomposition rate is still slower than the adsorption rate. If the solvent remains on the filter 30 after passing through the ultraviolet irradiation unit 33 and before being transported to a position where the next adsorption is performed, the amount of the residual solvent is increased by repeating the operation, and the conduit unit 31. Will be discharged out of the machine as steam. In order to prevent such a situation, the ultraviolet irradiation part is longer than the length of the pipe line part 31 in the direction in which the filter 30 is conveyed so that the time during which the filter 30 is irradiated with ultraviolet light is longer than the time for adsorbing the solvent. The length 33 is set longer.
[0037]
FIG. 6 shows a filter portion 16B according to the second embodiment of the present invention.
[0038]
In the second embodiment, the filter 40 is suspended in the form of an endless belt with two shafts 34 and 35, and one of the shafts 34 is rotated by a drive system (not shown), so that the filter 40 travels in the direction of the arrow. The
[0039]
Next, the operation of the filter unit 16B will be described.
[0040]
When the printing operation starts, the filter 40 is conveyed at a constant speed in the direction of the arrow by the rotation of the shafts 34 and 35. Adsorption of the solvent vapor is performed in the pipe section 31 and decomposition is performed in the ultraviolet irradiation section 33.
[0041]
In this embodiment, the solvent vapor is configured to pass through the filter 40 twice. The filter 40 from which the solvent has been removed by the ultraviolet irradiation unit 33 is conveyed again to the pipe line unit 31 and repeats adsorption and decomposition of the solvent vapor.
[0042]
As described above, the solvent vapor passes through the filter 40 a plurality of times, so that the chance of adsorbing to the filter 40 increases, and the amount of vapor released to the outside of the apparatus can be further reduced.
[0043]
FIG. 7 shows a filter unit 16C according to the third embodiment of the present invention.
[0044]
In the third embodiment, the solvent vapor is adsorbed by the pipe line portion 31 and the solvent vapor is decomposed by the ultraviolet irradiation unit 33 in the same manner as described above. Hydrocarbon, which is a solvent, is decomposed into carbon dioxide and water by the oxidation action of titanium oxide, but when water that has not been converted to water vapor reaches the pipe section 31 again while adhering to the filter 40, the solvent Even if the vapor is adsorbed on the filter 40, water intervenes between the filter surface and the solvent vapor, making it difficult for both to contact.
[0045]
Since the solvent is decomposed only after the two come into contact with each other, the decomposition efficiency is lowered if the two are difficult to contact. Therefore, a rubber blade 50 as a removing means is installed at the outlet of the ultraviolet irradiation unit 33 on the surface of the filter 40 that has passed through the ultraviolet irradiation unit 33, and water is removed by rubbing with the installed rubber blade 50. Thereby, since the filter surface is always exposed, there are many opportunities to come into contact with the solvent, and the decomposition efficiency is high.
[0046]
The same effect can be obtained even if the rubber blade 50 is disposed at a position facing the shaft 34.
[0047]
【The invention's effect】
As described above, the present invention allows the solvent vapor to be adsorbed on the filter and decomposed by irradiating the solvent vapor adsorbed on the filter with ultraviolet rays, so that the adsorption performance of the filter can be maintained for a long time. Therefore, the number of filter replacements can be reduced, and the replacement work is not time-consuming.
[0048]
Further, since the solvent vapor is adsorbed while moving the filter, the solvent vapor can be adsorbed uniformly on the entire surface of the filter, and the decomposition efficiency of the solvent at the time of ultraviolet irradiation can be improved.
[0049]
Furthermore, since the solvent vapor is passed through the filter a plurality of times, the number of times the solvent vapor is adsorbed can be increased, and the amount of the solvent vapor released to the outside can be reduced.
[0050]
Moreover, since the ultraviolet irradiation time is longer than the adsorption time of the solvent vapor of the filter, the solvent vapor can be reliably decomposed and can be prevented from being released to the outside.
[0051]
Moreover, since the removing means for removing the water adhering to the surface of the filter is provided, the filter surface is always exposed without being covered with water. Therefore, the opportunity for the filter to come into contact with the solvent vapor increases, and the decomposition efficiency can be improved.
[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 diagram schematically showing a solvent vapor recovery unit of a wet electrophotographic apparatus.
FIG. 3 is a diagram for explaining adsorption and decomposition operations of a solvent vapor by a filter.
FIG. 4 is a diagram for explaining the decomposition operation of the solvent vapor adsorbed by the filter.
FIG. 5 is a view showing a filter part of a solvent vapor recovery part.
FIG. 6 is a diagram showing a filter unit according to a second embodiment of the present invention.
FIG. 7 is a diagram showing a filter unit according to a third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Latent image holding body 4a-4d ... Developing apparatus (developing means)
5. Transfer device (transfer means)
6 ... Intermediate transfer medium 8 ... Backup roller 9 ... Heater (heating means)
10 ... paper (transfer medium)
13 ... Cooling section (recovery means)
14 ... Suction means (pump)
15 ... Collection container (collection means)
16A, 16B, 16C ... filter unit 30, 40 ... filter 31 ... UV lamp (ultraviolet irradiation means)
50. Rubber blade (removal means)

Claims

Latent image forming means for forming an electrostatic latent image on the latent image holding member;
Developing means for supplying a developer containing a solvent to the electrostatic latent image formed by the latent image forming means to make a visible image;
A transfer means for transferring the visible image visualized by the developing means to the intermediate transfer body once, and then transferring it onto the transfer body;
Heating means for heating the visible image on the intermediate transfer member;
A suction means for sucking the solvent vapor in the visible image evaporated by heating of the heating means;
A recovery means for cooling and liquefying and recovering the solvent vapor sucked by the suction means;
A filter that adsorbs solvent vapor exhausted from the suction means without being liquefied by the recovery means;
Driving means for moving the filter;
Ultraviolet irradiation means for irradiating the solvent vapor adsorbed by the filter moved by the driving means with ultraviolet rays for decomposition;
An image forming apparatus comprising:

Latent image forming means for forming an electrostatic latent image on the latent image holding member;
Developing means for supplying a developer containing a solvent to the electrostatic latent image formed by the latent image forming means to make a visible image;
A transfer means for transferring the visible image visualized by the developing means to the intermediate transfer body once, and then transferring it onto the transfer body;
Heating means for heating the visible image on the intermediate transfer member;
A suction means for sucking the solvent vapor in the visible image evaporated by heating of the heating means;
A recovery means for cooling and liquefying and recovering the solvent vapor sucked by the suction means;
A filter that adsorbs solvent vapor exhausted from the suction means without being liquefied by the recovery means;
Drive means for moving the filter between a first position for adsorbing the solvent vapor and a second position different from the first position;
Ultraviolet irradiation means for irradiating the solvent vapor adsorbed on the filter moved to the second position by the driving means with ultraviolet rays for decomposition;
An image forming apparatus comprising:

Latent image forming means for forming an electrostatic latent image on the latent image holding member;
Developing means for supplying a developer containing a solvent to the electrostatic latent image formed by the latent image forming means to make a visible image;
A transfer means for transferring the visible image visualized by the developing means to the intermediate transfer body once, and then transferring it onto the transfer body;
Heating means for heating the visible image on the intermediate transfer member;
A suction means for sucking the solvent vapor in the visible image evaporated by heating of the heating means;
A recovery means for cooling and liquefying and recovering the solvent vapor sucked by the suction means;
A filter that adsorbs solvent vapor exhausted from the suction means without being liquefied by the recovery means;
Both ends of the filter are wound around a winding shaft, and the winding shaft is rotated to move between a first position where the solvent vapor is adsorbed and a second position different from the first position. Driving means;
Ultraviolet irradiation means for irradiating the solvent vapor adsorbed on the filter moved to the second position by the driving means with ultraviolet rays for decomposition;
An image forming apparatus comprising:

Latent image forming means for forming an electrostatic latent image on the latent image holding member;
Developing means for supplying a developer containing a solvent to the electrostatic latent image formed by the latent image forming means to make a visible image;
A transfer means for transferring the visible image visualized by the developing means to the intermediate transfer body once, and then transferring it onto the transfer body;
Heating means for heating the visible image on the intermediate transfer member;
A suction means for sucking the solvent vapor in the visible image evaporated by heating of the heating means;
A recovery means for cooling and liquefying and recovering the solvent vapor sucked by the suction means;
A filter that adsorbs the solvent vapor exhausted from the suction means without being liquefied by the recovery means through a first part and a second part different from the first part; and
Driving means for moving the filter;
Ultraviolet irradiation means for irradiating the solvent vapor adsorbed by the filter moved by the driving means with ultraviolet rays for decomposition;
An image forming apparatus comprising:

Latent image forming means for forming an electrostatic latent image on the latent image holding member;
Developing means for supplying a developer containing a solvent to the electrostatic latent image formed by the latent image forming means to make a visible image;
A transfer means for transferring the visible image visualized by the developing means to the intermediate transfer body once, and then transferring it onto the transfer body;
Heating means for heating the visible image on the intermediate transfer member;
A suction means for sucking the solvent vapor in the visible image evaporated by heating of the heating means;
A recovery means for cooling and liquefying and recovering the solvent vapor sucked by the suction means;
A filter that adsorbs the solvent vapor exhausted from the suction means without being liquefied by the recovery means through the first part and the second part spaced apart from the first part;
Drive means for running the filter endlessly;
Ultraviolet irradiation means for irradiating the solvent vapor adsorbed on the filter traveling by the driving means with ultraviolet rays for decomposition;
An image forming apparatus comprising:

5. The image forming apparatus according to claim 1, wherein an irradiation time of the ultraviolet rays by the ultraviolet irradiation unit is made longer than an adsorption time of the solvent vapor by the filter.

The image forming apparatus according to claim 1, further comprising a removing unit that removes a decomposition product generated in the filter by the ultraviolet irradiation of the ultraviolet irradiation unit.