JP3715538B2

JP3715538B2 - Developing device and image forming apparatus having the same

Info

Publication number: JP3715538B2
Application number: JP2001066081A
Authority: JP
Inventors: 将実佐久間; 太介上村; 潔戸泉; 克己足立
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2001-03-09
Filing date: 2001-03-09
Publication date: 2005-11-09
Anticipated expiration: 2021-03-09
Also published as: JP2002268374A

Description

【０００１】
【発明の属する技術分野】
本発明は、現像剤を用いて像担持体上に形成される静電潜像を現像する現像装置であって、特に、進行波電界を用いて現像剤を搬送する機構を利用する現像装置及びこれを備えた画像形成装置に関するものである。
【０００２】
【従来の技術】
複写機、プリンタ等の電子写真プロセスを用いた画像形成装置に適用される現像装置としては、現在、像担持体に現像剤担持体を接触させずに現像を行う非接触方式の現像装置が注目されており、パウダークラウド法・ジャンピング法や電界カーテン（進行波電界）を利用した方法が提案されている。
【０００３】
電界カーテンを用いた方法においては、現像終了後、電界カーテンのパネル（現像剤搬送手段）にトナー（現像剤）が移動を中止して堆積すると、次に現像するまでの時間が長ければ、堆積したトナーの電荷が中和され帯電量不足のトナーが多量に発生して、次の現像時にカブリの多い画像となったり、トナーの飛散が発生し装置内部が汚れるという問題があった。
【０００４】
この問題を解決する方法として、特開昭６３−１３０７８号公報においては、以下の手段が開示されている。
【０００５】
ｉ）現像が終了すると、規制板を駆動し電界カーテンパネルにトナーが進入するのを防ぐと共に、引き続き電極に３相交流を印加して電界パネル上から完全に現像剤を搬送搬出させた後、スイッチを切るシーケンス制御を行う。
【０００６】
ii)電界カーテンを上部と下部から構成し、現像中は共にトナーを同方向に搬送し、現像終了後には下部の電界カーテンに印加する電圧の位相をずらしてトナーを逆方向に搬送して現像部（現像領域）にトナーが搬送されるのを遮断し、電界カーテンパネルのトナーが全て搬送排出された後、電源を遮断する。
【０００７】
【発明が解決しようとしている課題】
しかしながら、上記公報（特開昭６３−１３０７８号）の技術には下記に示す問題がある。
ａ）電界カーテンパネルヘのトナーの供給を防ぐのに、機械的に作動する規制板を用いているが、この方法ではトナーを確実に遮断するのは困難であり、現像パネル上からトナーを完全に排出するのに時間を要する。
ｂ）電界カーテンパネルを上部と下部に２分して構成すると、分割した領域で電極の間隔が他と異なりこの領域で電界が不均一となる。よって、トナーが均―に搬送されなくなり、画像に濃度ムラが現れるおそれがある。また、電極を２分すると電界カーテンパネルの構成が複雑になる。
【０００８】
本発明は、規制板等の機械的手段を設けることなく、画像形成終了時に現像剤の供給を停止することを目的とし、より確実に現像剤搬送手段に現像剤が残留するのを防ぎ、常に高画質の画像を安定に得ることのできる現像装置及びそれを備えた画像形成装置を提供するものである。
【０００９】
【課題を解決するための手段】
上記課題を解決するために、本発明においては、画像形成終了時に現像剤供給手段の駆動を停止させることにより、現像剤供給手段から現像剤搬送手段へ不要な現像剤の供給を防止することができる。
【００１０】
また、画像形成終了時に現像剤供給手段に現像剤の帯電極性と逆極性の電圧を印加することにより、現像剤供給手段から現像剤搬送手段へ不要な現像剤の供給を防止することができる。さらに、画像形成終了時に、現像剤供給手段の駆動停止と電圧印加手段による現像剤帯電極性と逆極性の電圧印加とを組み合わせて行えば、現像剤搬送手段への現像剤の不要な供給がより確実に防止することができる。
【００１１】
さらに、現像剤搬送手段において、現像剤供給手段が接触もしくは当接する位置近傍（現像剤供給領域）の進行波発生電極を他の領域の進行波発生電極とは別に制御する構成を採用すれば、現像剤供給手段から現像剤搬送手段への現像剤の供給を抑制する上で様々な方法を適用することができる。
【００１２】
具体的には、画像形成終了時に、現像剤供給領域の進行波発生電極にのみ多相の交流電圧を印加しないようにすれば、この領域には進行波電界が形成されず不要な現像剤の供給が防止されるので、現像剤搬送手段上の現像剤を効率よく回収することができる。
【００１３】
また、画像形成終了時に、現像剤供給領域の進行波発生電極に画像形成時とは逆方向の進行波電界を形成するようにすれば、現像剤は逆方向に搬送されるので不要な現像剤の供給が防止され、現像剤搬送手段上の現像剤を効率よく回収することができる。
【００１４】
上記の現像装置を画像形成装置に適用すれば、画像形成終了時に、現像剤搬送手段上の現像剤が速やかに回収され、次の現像時にカブリ等が発生することがなく、品質の良い画像を出力することのでき、また、画像形成装置内での現像剤の飛散も抑制され、メンテナンス性の良い画像形成装置を提供できることになる。
【００１５】
【発明の実施形態】
［第１の実施形態］
（電子写真プロセスの構成）
図１は、本発明の現像装置が適用される電子写真プロセスを用いた画像形成装置の一例を示す縦断面図である。この電子写真プロセスでは、像担持体としての感光体１に原稿像あるいはホストコンピュータからのデータに対応した静電潜像が形成され、その静電潜像が現像装置２からの現像剤によって可視化され、紙等の記録媒体３上に転写されて画像形成が行われる。
【００１６】
感光体１の周囲には、帯電装置４、露光装置５、現像装置２、転写装置６、クリーニング装置７、除電装置８等が、感光体１の回転方向の上流側から順に配置されている。そして、記録媒体３の搬送方向下流側には定着装置９が配置されている。
【００１７】
感光体１は、例えばアルミニウム等の金属ドラムを基材１０として、その外周面上にアモルファスシリコン（ａ−Ｓｌ）、セレン（Ｓｅ）や有機光半導体（ＯＰＣ）等の光導電層１１が薄膜状に形成されて構成されている。
【００１８】
帯電装置４は、例えばタングステンワイヤ等の帯電線、金属製のシールド板、及びグリット板よりなるコロナ帯電器や、帯電ローラあるいは帯電ブランなどで実現される。露光装置５は例えば半導体レーザで実現される。転写装置６は、例えばコロナ帯電器、帯電ローラ、あるいは帯電ブラシなどで実現される。定着装置９は、例えば加熱ローラと加圧ローラとからなる上下ローラで実現される。
【００１９】
感光体１は、図１に示す矢印Ｃ方向に回転し、まず帯電装置４によって一様に帯電され、次に画像情報に応じて露光装置５によって光照射がなされる。このようにして、感光体１上に形成された静電潜像は、感光体１と現像装置２との間に形成される現像電界により現像装置内の現像剤（トナー）が移動し、トナー像として可視化される。このトナー像は、転写装置６によって記録媒体３上に転写され、定着装置９において加熱定着される。トナー像が転写された後、感光体１上に残留したトナーは、クリーニングブレードなどのクリーニング装置７によって除去され、また感光体上に残留した電荷は、除電ランプなどの除電装置８によって除電される。
【００２０】
（現像装置の構成）
図２は現像装置の構成を示す概略図である。本実施形態の現像装置２は、図２に示すように、現像ケーシング１２と、トナー搬送部材１３（現像剤搬送手段）と、トナー混合手段１４と備えている。ケーシング１２はトナー１５を内部に収容するものである。トナー混合手段１４は、ケーシング１２内に収容されているトナー１５を混合するためのもので、本実施の形態では、ミキシングパドル（ＭＸパドル）が用いられている。
【００２１】
トナー搬送部材１３は、感光体１の現像領域Ａに対向してケーシング１２の開口部に配置され、半円孤状に形成されている。トナー搬送部材１３の形状はこれに限定されるものではなく、例えば、平面状のものでも構わない。このトナー搬送部材１３には、多相交流電源１９と現像バイアス電源２０とが直列に接続されている。
【００２２】
また、トナー１５を搬送する表面とは反対側に、トナー搬送部材１３を保持する支持部材１６が設けられている。この支持部材１６は、トナー搬送部材１３を感光体１の現像領域Ａに対向した状態を保持するためのもので、その構成は特に限定されるものではない。たとえば、ＡＢＳ（Acrylonitrile−Butadiene−Styrene：アクリロニトリル・ブタジエン・スチレン）樹脂などを挙げることができる。
【００２３】
トナー搬送部材１３の下方端部には、トナー搬送部材１３の表面上を搬送されるトナーを供給する供給部材１７（現像剤供給手段）が設けられている。一方、トナー搬送部材１３の上方端部には、トナー搬送部材１３の表面のトナーを回収する回収部材１８（現像剤回収手段）が設けられている。供給部材１７及び回収部材１８の何れも、ローラ状に形成され、半円弧状のトナー搬送部材１３の表面に回転可能に接触している。
【００２４】
供給部材１７は、ケーシング１２内に収容されているトナー１５をトナー搬送部材１３に供給するためのもので、その材質としては特に限定されるものではないが、たとえばシリコーン、ウレタン、ＥＰＤＭ（エチレン−プロピレン−ジエン−メチレン共重合体）などのソリッドゴム、発泡ゴムなどが挙げられる。また、カーボンブラックやイオン導電剤を添加することによって導電性を付与して電圧印加も可能に構成してもよい。
【００２５】
また、供給部材１７とトナー搬送部材１３との接触圧力や供給部材１７に印加する電圧値を適切な値に設定し、供給部材１７にトナーを帯電させる機能を付加するようにしても良い。あるいは、供給部材１７の前段に、例えば薄板状のブレード（材質としては、供給部材１７と同じものが使用可能）を設け、トナーを帯電させるようにしても構わない。
【００２６】
一方、回収部材１８は、感光体１上の静電潜像の現像に寄与しないトナーを回収して現像装置２内に戻すためのものであり、その材質としては、特に限定されないが、たとえば供給部材１７と同様のものを使用することができる。
【００２７】
ここで、トナー搬送部材１３を構成する進行波発生電極について説明する。進行波発生電極２２は、例えば図３に示すように微小電極２２が１００ｄｐｉ（約２５４μｍ）〜３００ｄｐｉ（約８５μｍ）ピッチの間隔を保って互いに平行になるように配置され、３本または４本の微小電極２２を１組として形成されている。
【００２８】
この進行波発生電極２２は、トナー搬送部材１３の長さ方向でほぼ全域に配列されており、図２及び図５に示すように、その両端部の供給部材１７及び回収部材１８と接触する位置近傍のトナー供給領域及びトナー回収領域まで配置されている。
【００２９】
これら各組の電極２２には３または４相の交番電圧が印加され、進行波発生電極上に進行波電界が形成されトナーが搬送される。この進行波発生電極に印加する交番電圧は、進行波発生電極間で絶縁破壊が発生しないように、例えば１０Ｖ〜１ｋＶ程度の値に設定され、周波数としてはトナーの応答性を基に１００Ｈｚ〜１０ｋＨｚの範囲内の値が使用される。
【００３０】
なお、交番電圧や周波数の値は、進行波発生電極の素子の形状、トナーの搬送速度、トナーの使用材料等によって適性値を設定すれば良い。また、トナー搬送部材１３には、図３に示すように、感光体１とトナー搬送部材１３との間に現像電界が形成されるように現像バイアス直流電源２０より直流電圧が印加されるようになっている。
【００３１】
トナー搬送部材１３は、電界カーテン作用によりトナーを搬送するものであり、図３に示すように、絶縁層２３内に、電界カーテン作用を発生させる進行波発生電極２２が、複数本を一組として複数組が順次連続して埋設されている。これらの電極２２にトナー搬送のための多相交流電源１９から、多相の交流電圧が印加されることにより、トナー搬送部材１３の表面に平行となる方向に電界カーテンが発生し、これによって現像領域まで電界カーテン作用によりトナーを搬送するようになっている。
【００３２】
トナー搬送部材１３の具体例を挙げると、たとえば、厚さ２５μｍのポリイミドからなる基材２４と、厚さ１８μｍの銅製の進行波発生電極２２が埋設された絶縁層２３と、厚さ２５μｍのポリイミドからなる表面保護層２５が下層から上層に向けて積層配列された構成を挙げることができる。
【００３３】
また、進行波発生電極２２は、幅４０〜１３０μｍの微小電極となっており、これが１００ｄｐｉ（dot per inch）〜３００ｄｐｉ、すなわち約２５４μｍ〜８５μｍのピッチの間隔を保って互いに平行に配置されている。
【００３４】
本実施の形態では、図４に示すような４本の微小電極▲１▼〜▲４▼を１組とし、これら各組の電極に対して、図４に示すような電圧波形の４相の交番電圧を印加して、進行波発生電極上に進行波電界を形成しているが、特にこれに限定されるものではなく、３本の微小電極を１組として３相の交番電圧を印加しても構わない。
【００３５】
また、図３に示すように、感光体１とトナー搬送部材１３との間に現像電界が形成されるようにバイアス電圧（現像バイアス）が印加されていることが好ましい。
【００３６】
上記電圧波形は正弦波や台形波などでも良く、電圧値の範囲としては、１０Ｖ〜１ｋＶ程度が好ましく、周波数の範囲としては、１００Ｈｚ〜１００ｋＨｚが好ましく用いられる。ただし、これらの電圧値や周波数については、進行波発生電極素子の形状、トナーの搬送速度、トナーの使用材料などによって適性値を設定すればよく、特に限定されるものではない。
【００３７】
（現像装置の動作）
次に、上記構成の現像装置２の動作について説明する。トナーケーシング１２内に保有されたトナー１５は、図２の矢印Ｂ方向に回転するＭＸパドル１４により撹拌され、トナー１５は供給部材１７付近に供給される。供給部材１７付近に存在するトナーは、供給部材１７により帯電されてトナー搬送部材１３に供給される。
【００３８】
前記の工程を経て帯電されたトナーは、トナー搬送部材１３により形成される進行波電界によって図２に示す矢印ａ方向に搬送され、現像領域（感光体と面するポイント）で感光体上の静電潜像を行う。現像に寄与しなかったトナーはさらにａ方向に搬送され、回収部材１８を介して、トナーケーシング１２内に再び戻る。
【００３９】
（画像形成終了後のプロセス）
進行波電界を用いた現像装置２では、現像終了後、同時に進行波電界の形成を終了すると、トナー搬送部材１３上にトナーが残留し、次回の現像時までの時間が長い場合に、トナー搬送部材１３上残留しているトナーの電荷が中和され、帯電量が不足するおそれがある。
【００４０】
そこで、本実施形態では、画像形成終了後に、供給部材１７からのトナーの供給を停止し、かつ進行波電界を一定時間かけることにより、トナー搬送部材上に残留トナーの発生するのを防ぐようにしている。
【００４１】
なお、進行波電界をかける一定時間は、例えば、トナー搬送部材１３上のトナーが回収部材１８に回収されるまでの時間よりも少なくとも長く設定された時間をいい、この時間はトナー搬送部材１３の長さとトナー搬送速度から知ることができる。
【００４２】
図５はトナー搬送部材１３に供給部材１７が配置されている箇所の構成を示す図である。上述のごとく、トナー搬送部材１３の進行波発生電極２２は供給部材１７と接触する位置近傍のトナー供給領域まで配置されている。このトナー供給領域に対向する供給部材１７には、これを回転駆動させるモータなどの駆動手段３０と、この駆動手段３０を制御する制御手段３１とが設けられている。
【００４３】
制御手段３１は、例えば、ＣＰＵ（Central Processing Unit）を備え、画像形成開始信号を受け取ると駆動手段３０を駆動し、画像形成終了信号を受け取ると駆動手段３０の駆動を停止制御するものである。
【００４４】
すなわち、画像形成が終了したことが判断されると、供給部材１７の駆動が停止され、供給部材１７からトナー搬送部材１３へのトナーの供給が停止される。これにより、画像形成時にトナー搬送部材１３上に供給されたトナーのみをトナー搬送部材１３で搬送し、回収部材１８で回収すれば良いことになる。
【００４５】
このように、本実施形態においては、従来のごとく規制板等の機械的手段を作動させるのではなく、供給部材１７の駆動を制御することによってトナーの供給を制御し、画像形成終了後にトナー搬送部材１３上にトナーが残留するのを防ぐようにしている。
【００４６】
［第２の実施形態］
図６は第２の実施形態を示すトナー搬送部材１３に供給部材１７が配置されているトナー供給領域の構成図である。本実施形態では、図５に示した構成に付加して、供給部材１７に電圧を印加する電圧印加手段３２が設けられ、制御手段３１は、駆動手段３０及び電圧印加手段３２を制御するようにしている。
【００４７】
電圧印加手段３２は、少なくとも画像形成終了時にトナーの帯電極性とは逆極性の電圧を印加して供給部材１７からトナー搬送部材１３にトナーが供給されるのを抑制するようにしている。
【００４８】
勿論、画像形成時には、トナー搬送部材１３と供給部材１７との間に電圧を印加することにより、トナーの帯電を制御すると共に供給部材１７からトナー搬送部材１３へのトナーの供給量を制御するようにしても構わない。
【００４９】
本実施形態では、制御手段３１が画像形成終了信号を受け取ると、供給部材１７からトナー搬送部材１３へのトナー移動を防ぐために、電圧印加手段３２に画像形成時とは逆のバイアスを印加する。例えば、進行波電界を０〜−４００Ｖとすると、供給部材１７には、画像形成時に−５００Ｖが、画像形成終了時には＋１００Ｖが印加される様に設定すると良い。なお、ここでは、トナーの帯電極性はマイナスとしている。
【００５０】
図７は前記の条件でトナー搬送部材１３と供給部材１７に印加する電圧波形の例を示した図である。これにより、画像形成中にトナー搬送部材１３上に供給されたトナーのみを搬送し回収すれば良く、トナー搬送部材１３上にトナーが残留するのを防ぐことができる。
【００５１】
なお、上記では、画像形成時に電圧印加手段３２により供給部材１７に電圧を印加する場合の例を示しているが、画像形成時は電圧を印加せずに、画像形成終了時にトナーの帯電極性とは逆の電圧を印加するように制御しても良い。
【００５２】
この動作は、上記第１の実施形態に記載した、画像形成終了時に供給部材１７の駆動を停止する方法と組み合わせることも可能であり（図６の破線部参照）、これにより、より確実に画像形成終了時のトナーの供給を停止することができる。
【００５３】
［第３実施形態］
図８は第３の実施形態を示すトナー搬送部材１３のトナー供給領域の構成図である。本実施形態では、画像形成終了後、トナー搬送部材１３上にトナーが残留するのを防ぐために、トナー供給領域１３ａの進行波発生電極２２は他の領域の進行波発生電極とは別に制御されるように構成されている。
【００５４】
すなわち、トナー供給領域１３ａにある４つの進行波発生電極２２よりなる１つのユニットにスイッチ３４が設けられ、このスイッチ３４が制御手段３１によりオン・オフ制御され、多相交流電源１９からの電源をＯＮ・ＯＦＦできるようになっている。なお、スイッチ３４を設けるユニットは、１つではなく数ユニットでもよい。上記の場合、トナー搬送部材１３を分割する必要はなく、進行波発生電極２２のユニットを分割することで目的を達成することができる。
【００５５】
このスイッチ３４の制御は、画像形成時にはスイッチ３４をＯＮにして進行波発生電極により電界カーテンを形成するようにし、画像形成終了後に、トナー供給領域１３ａの進行波発生電極２２に対して、スイッチをオフ（０Ｖ）にして電圧印加を停止する。
【００５６】
これにより、画像形成終了後には、供給部材１７から供給されるトナーがトナー搬送部材１３まで搬送されなくなり、画像形成時にトナー搬送部材上に供給された現像剤のみを搬送し回収すれば良く、トナー搬送部材上にトナーが残留するのを防ぐことができる。
【００５７】
この動作は、上記第１の実施形態および第２の実施形態に記載した、画像形成終了時に供給部材１７の駆動を停止する手法、および供給部材１７に逆バイアスを印加する方法と適宜組み合わせ、これにより、より確実にトナー搬送部材１３上にトナーが残留するのを防止することができる。
【００５８】
［第４の実施形態］
図９は第４の実施形態を示すトナー搬送部材１３のトナー供給領域の構成図である。本実施形態では、図８に示した構成に付加して、トナー供給領域１３ａの進行波発生電極２２に別の多相交流電源３５により多相交流電圧を印加するようにしたもので、トナー供給領域１３ａの進行波発生電極２２は、第１の多相交流電源１９及び第２の多相交流電源３５に接続され、両多相交流電源１９、３５からの電力供給を切換える切換えスイッチ３４が設けられている。
【００５９】
第２の多相交流電源３５は、図１０に示すように、トナー供給領域の電極２２に対して、画像形成終了後に、第１の多相交流電源１９による画像形成時と逆位相となる多相の交流電圧を印加するようになっている。
【００６０】
上記構成においては、画像形成終了時に、第１の多相交流電源１９による画像形成時と逆位相となる多相の交流電圧を印加するため、トナー供給領域１３ａのトナーは逆方向に搬送されて供給部材１７からトナー搬送部材１３にトナーが供給されるのが抑制される。
【００６１】
このとき、他の領域の進行波発生電極２２には、第１の多相交流電源１９より多相の交流電圧が印加されているので、トナー搬送部材１３上のトナーは、画像形成時と同方向に搬送されて回収部材１８により回収される。従って、トナー搬送部材１３上にトナーが残留するのを防ぐことができる。
【００６２】
この動作は、上記第１の実施形態に記載した、画像形成終了時に供給部材１７の駆動を停止する手法と組み合わせることも可能であり、これにより、より確実にトナー搬送部材１３上のトナーが残留するのを防止することができる。
【００６３】
［第５実施形態］
図１１は第５の実施形態である被覆部材を備えた現像装置の構成図である。本実施形態では、トナー搬送部材１３に対して、その周面を覆うとともにトナー搬送部材１３に対して移動する被覆部材４０を備えた構成である。このような構成においても、上記第１〜第４の実施形態で示した供給部材１７に対する制御やトナー供給領域における進行波発生電極に対する制御を適用してトナー搬送部材１３上（被覆部材４０上）のトナーの残留を防止することができる。
【００６４】
この被覆部材４０は、無端ベルト状をなし、支持部材１６上に配置されたトナー搬送部材１３と駆動ローラ４１及び従動ローラ４２とにより、少なくとも３点で支持され、トナー搬送部材１３の表面側に密着配置されている。
【００６５】
この被覆部材４０は、駆動ローラ４１により、トナー搬送部材１３の周面を覆ってトナーの搬送速度に対して、ほぼ静止しているとみなされる速度で図１１の矢印ｄで示す方向に駆動され、トナー搬送部材１３の帯電を防止し、かつトナーの固着を防止するために用いられている。
【００６６】
被覆部材４０の除電は、ローラ状の回収部材１８自体に導電性を付与し、除電機能を持たすことによりなされる。被覆部材４０の材料としては、ポリイミド、ＰＥＴ（ポリエチレンテレフタレート）、ポリ４フッ化エチレン、ポリフッ化エチレンプロピレン、ＰＴＦＥ（ポリテトラフルオロエチレン）等の有機絶縁材料や、シリコン、イソプレン、ブタジエン等のゴム材料にカーボンブラックやイオン性の導電材を分散もしくは相溶させて形成されたものが使用される。
【００６７】
被覆部材４０に接触配置される掻き取り部材４３は、ＳＵＳ（ステンレス）、ニッケルコートした鉄、あるいはウレタンやシリコンゴムなどを材料とし、被覆部材４０上に残留するトナーを掻き取り、ケーシング１２内に戻すものである。
【００６８】
この掻き取り部材４３として、カーボンブラックやイオン等の導電剤をウレタンゴム・シリコン等に混ぜたものや、上記したＳＵＳ（ステンレス）、ニッケルコートした鉄等の金属を用いることで、トナーを掻き取ると共に被覆部材４３自体の除電を兼ねるようにすることもできる。
【００６９】
上記構成においては、トナー搬送部材１３上に密着して被覆部材４０を設けること、被覆部材４０に掻き取り部材４３を配置すること、回収部材１８に除電機能を付与することを除けば、図２に示した現像装置２と同じ構成である。従って、第１〜第４の実施形態に示した方法を適用して、画像形成終了後、被覆部材４０上に残留するトナーを回収することができる。
【００７０】
なお、本発明は上記実施形態に限定されるものではなく、本発明の範囲内で多くの修正・変更を加えることができるのは勿論である。例えば、供給部材１７及び回収部材１８は、上記実施形態ではローラ状のものを例示したが、これに限らずブレード状のものなど、形状を問わず適用可能である。また、供給部材１７や回収部材１８は、トナー搬送部材１３に対して接触する態様のものに限らず、近接配置された態様のものであってもよい。
【００７１】
【発明の効果】
以上の説明から明らかな通り、本発明によると、画像形成終了時において、現像剤供給手段の駆動を停止するか、あるいは現像剤供給手段に現像剤の帯電極性と逆極性の電圧を印加するという簡単な制御を行うことで、現像剤供給手段から現像剤搬送手段へ不要な現像剤の供給を防ぐことができる。従って、画像形成終了時に現像剤搬送手段上に存在する現像剤のみを進行波電界により搬送し現像剤回収手段により速やかに回収することができ、現像剤搬送手段上に現像剤が残留するのを抑制することができる。
【００７２】
また、現像剤搬送手段の現像剤供給領域の進行波発生電極を他の領域の進行波発生電極とは別に制御するように構成することで、画像形成終了時に、現像剤供給手段が当接する近傍の進行波発生電極にのみ多相の交流電圧を印加しない、あるいは、画像形成時とは逆方向の進行波発生電界を形成する等、現像剤供給手段から現像剤搬送手段への現像剤の供給を抑制する上で様々な方法を適用することができる。
【００７３】
さらに、本発明の現像装置を搭載した画像形成装置においては、画像形成終了時に現像剤搬送手段上の現像剤が速やかに回収されるので、次の現像時にカブリ等が発生することがない品質の良い画像を出力することができ、また、現像剤の飛散も抑制されるのでメンテナンス性の良い画像形成装置を提供することができる。
【図面の簡単な説明】
【図１】本発明に係る現像装置が適用される画像形成装置の概略構成図
【図２】同じく現像装置の概略構成図
【図３】図２の現像装置に用いられるトナー搬送部材の構成図
【図４】図３に示すトナー搬送部材に印加される電圧波形の例を示す図
【図５】本発明の第１の実施形態であるトナー搬送部材と供給部材の構成例を示す図
【図６】本発明の第２の実施形態であるトナー搬送部材と供給部材の構成例を示す図
【図７】図６に示すトナー供給領域の画像形成時と画像形成終了時において各部材に印加される電圧波形を示す図
【図８】本発明の第３の実施形態であるトナー搬送部材と供給部材の構成例を示す図
【図９】本発明の第４の実施形態であるトナー搬送部材と供給部材の構成例を示す図
【図１０】図９に示すトナー搬送部材に画像形成終了時に印加される電圧波形を示す図
【図１１】本発明の第５の実施形態であるトナー搬送部材の周面に被覆部材を設けた現像装置の構成図
【符号の説明】
１感光体
２現像装置
３記録媒体
１２ケーシング
１３トナー搬送部材（現像剤搬送手段）
１３ａトナー供給領域
１４ＭＸパドル（混合手段）
１５トナー
１６支持部材
１７供給部材（現像剤供給手段）
１８回収部材（現像剤回収手段）
１９多相交流電源
２０現像バイアス直流電源
２２進行波発生電極
２３絶縁層
２４基材
２５表面保護層
３０駆動手段
３１制御手段
３２電圧印加手段
３４スイッチ
３５第２の多相交流電源
４０被覆部材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developing device that develops an electrostatic latent image formed on an image carrier using a developer, and in particular, a developing device that uses a mechanism that transports the developer using a traveling wave electric field, and The present invention relates to an image forming apparatus including the same.
[0002]
[Prior art]
As a developing device applied to an image forming apparatus using an electrophotographic process such as a copying machine or a printer, a non-contact developing device that performs development without bringing a developer carrier into contact with an image carrier is currently attracting attention. The methods using the powder cloud method, jumping method, and electric field curtain (traveling wave electric field) have been proposed.
[0003]
In the method using an electric field curtain, after development is completed, if toner (developer) stops moving and accumulates on the electric field curtain panel (developer conveying means), it accumulates if the time until the next development is long. There has been a problem that the charge of the toner is neutralized and a large amount of toner with insufficient charge is generated, resulting in an image with much fog during the next development, or toner scattering occurs and the inside of the apparatus becomes dirty.
[0004]
As a method for solving this problem, Japanese Patent Application Laid-Open No. 63-13078 discloses the following means.
[0005]
i) After the development is completed, the regulation plate is driven to prevent the toner from entering the electric field curtain panel, and the three-phase alternating current is continuously applied to the electrodes to completely convey and carry out the developer from the electric field panel. Performs sequence control to switch off.
[0006]
ii) The electric field curtain is composed of an upper part and a lower part. Both toners are conveyed in the same direction during development, and after development, the phase of the voltage applied to the lower electric field curtain is shifted to convey the toner in the opposite direction. The toner is blocked from being conveyed to the portion (development area), and after all the toner on the electric field curtain panel is conveyed and discharged, the power supply is cut off.
[0007]
[Problems to be solved by the invention]
However, the technique described in the above publication (Japanese Patent Laid-Open No. 63-13078) has the following problems.
a) A mechanically operated regulating plate is used to prevent the toner from being supplied to the electric field curtain panel. However, it is difficult to reliably block the toner with this method, and the toner is completely removed from the developing panel. It takes time to discharge.
b) If the electric field curtain panel is divided into an upper part and a lower part, the distance between the electrodes is different in the divided area, and the electric field is nonuniform in this area. Therefore, the toner is not uniformly conveyed, and there is a possibility that density unevenness appears in the image. Further, when the electrode is divided into two, the configuration of the electric field curtain panel becomes complicated.
[0008]
The present invention aims to stop the supply of the developer at the end of image formation without providing a mechanical means such as a regulating plate, and more reliably prevent the developer from remaining in the developer conveying means, and always A developing device capable of stably obtaining a high-quality image and an image forming apparatus provided with the developing device are provided.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problem, in the present invention, it is possible to prevent unnecessary supply of developer from the developer supply unit to the developer transport unit by stopping the driving of the developer supply unit at the end of image formation. it can.
[0010]
Further, by applying a voltage having a polarity opposite to the charging polarity of the developer to the developer supply means at the end of image formation, it is possible to prevent unnecessary supply of developer from the developer supply means to the developer transport means. Further, at the end of image formation, if the driving of the developer supplying unit is stopped and the voltage application of the developer charging polarity by the voltage applying unit is combined with the opposite polarity, unnecessary supply of the developer to the developer conveying unit can be further improved. It can be surely prevented.
[0011]
Further, in the developer conveying means, if a configuration is adopted in which the traveling wave generating electrode in the vicinity of the position where the developer supplying means contacts or abuts (developer supplying area) is controlled separately from the traveling wave generating electrode in other areas, Various methods can be applied to suppress the supply of the developer from the developer supply unit to the developer transport unit.
[0012]
Specifically, at the end of image formation, if a multiphase AC voltage is not applied only to the traveling wave generating electrode in the developer supply area, a traveling wave electric field is not formed in this area, and unnecessary developer Since the supply is prevented, the developer on the developer conveying means can be efficiently recovered.
[0013]
Further, at the end of image formation, if a traveling wave electric field in the direction opposite to that at the time of image formation is formed on the traveling wave generating electrode in the developer supply region, the developer is conveyed in the opposite direction, so that an unnecessary developer Is prevented, and the developer on the developer conveying means can be efficiently recovered.
[0014]
If the above developing device is applied to an image forming apparatus, the developer on the developer conveying means is promptly collected at the end of image formation, and no fog or the like occurs at the next development, so that a high quality image can be obtained. In addition, it is possible to provide an image forming apparatus that is capable of outputting the image and that scattering of the developer in the image forming apparatus is suppressed, and that has good maintainability.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
(Configuration of electrophotographic process)
FIG. 1 is a longitudinal sectional view showing an example of an image forming apparatus using an electrophotographic process to which the developing device of the present invention is applied. In this electrophotographic process, an electrostatic latent image corresponding to the original image or data from the host computer is formed on the photosensitive member 1 as an image carrier, and the electrostatic latent image is visualized by the developer from the developing device 2. Then, the image is formed by being transferred onto the recording medium 3 such as paper.
[0016]
Around the photoreceptor 1, a charging device 4, an exposure device 5, a developing device 2, a transfer device 6, a cleaning device 7, a charge removal device 8, and the like are sequentially arranged from the upstream side in the rotation direction of the photoreceptor 1. A fixing device 9 is disposed downstream of the recording medium 3 in the conveyance direction.
[0017]
The photoconductor 1 has, for example, a metal drum such as aluminum as a base material 10, and a photoconductive layer 11 such as amorphous silicon (a-Sl), selenium (Se), or an organic optical semiconductor (OPC) is formed into a thin film on the outer peripheral surface thereof. It is formed and configured.
[0018]
The charging device 4 is realized by a corona charger including a charging wire such as a tungsten wire, a metal shield plate, and a grit plate, a charging roller, a charging bran, or the like. The exposure apparatus 5 is realized by a semiconductor laser, for example. The transfer device 6 is realized by, for example, a corona charger, a charging roller, or a charging brush. The fixing device 9 is realized by an upper and lower roller including a heating roller and a pressure roller, for example.
[0019]
The photosensitive member 1 rotates in the direction of arrow C shown in FIG. 1, is first uniformly charged by the charging device 4, and then is irradiated with light by the exposure device 5 in accordance with image information. In this way, the electrostatic latent image formed on the photoreceptor 1 is moved by the developer (toner) in the developing device due to the developing electric field formed between the photoreceptor 1 and the developing device 2. Visualized as an image. This toner image is transferred onto the recording medium 3 by the transfer device 6 and heated and fixed by the fixing device 9. After the toner image is transferred, the toner remaining on the photoreceptor 1 is removed by a cleaning device 7 such as a cleaning blade, and the charge remaining on the photoreceptor is neutralized by a neutralizing device 8 such as a static elimination lamp. .
[0020]
(Configuration of developing device)
FIG. 2 is a schematic diagram showing the configuration of the developing device. As shown in FIG. 2, the developing device 2 of the present embodiment includes a developing casing 12, a toner conveying member 13 (developer conveying means), and a toner mixing means 14. The casing 12 accommodates the toner 15 therein. The toner mixing unit 14 is for mixing the toner 15 accommodated in the casing 12, and in this embodiment, a mixing paddle (MX paddle) is used.
[0021]
The toner conveying member 13 is disposed in the opening of the casing 12 so as to face the developing area A of the photoreceptor 1 and is formed in a semicircular arc shape. The shape of the toner conveying member 13 is not limited to this, and for example, a planar shape may be used. A multiphase AC power source 19 and a developing bias power source 20 are connected to the toner conveying member 13 in series.
[0022]
A support member 16 that holds the toner transport member 13 is provided on the side opposite to the surface that transports the toner 15. The support member 16 is for holding the toner conveying member 13 in a state of facing the developing area A of the photosensitive member 1, and the configuration thereof is not particularly limited. For example, ABS (Acrylonitrile-Butadiene-Styrene: acrylonitrile-butadiene-styrene) resin can be used.
[0023]
A supply member 17 (developer supply means) for supplying toner conveyed on the surface of the toner conveyance member 13 is provided at the lower end of the toner conveyance member 13. On the other hand, a collecting member 18 (developer collecting means) for collecting toner on the surface of the toner conveying member 13 is provided at the upper end of the toner conveying member 13. Both the supply member 17 and the recovery member 18 are formed in a roller shape, and are in contact with the surface of the semicircular toner transport member 13 in a rotatable manner.
[0024]
The supply member 17 is for supplying the toner 15 accommodated in the casing 12 to the toner conveying member 13, and the material thereof is not particularly limited. For example, silicone, urethane, EPDM (ethylene-ethylene) is used. Solid rubber such as propylene-diene-methylene copolymer), foam rubber and the like. Further, it may be configured such that a voltage can be applied by adding conductivity by adding carbon black or an ionic conductive agent.
[0025]
Further, the contact pressure between the supply member 17 and the toner conveying member 13 and the voltage value applied to the supply member 17 may be set to appropriate values, and a function for charging the toner to the supply member 17 may be added. Alternatively, a thin blade (for example, the same material as that of the supply member 17 can be used) may be provided before the supply member 17 to charge the toner.
[0026]
On the other hand, the recovery member 18 is for recovering the toner that does not contribute to the development of the electrostatic latent image on the photosensitive member 1 and returning it to the developing device 2, and the material thereof is not particularly limited. The thing similar to the member 17 can be used.
[0027]
Here, the traveling wave generating electrode constituting the toner conveying member 13 will be described. For example, as shown in FIG. 3, the traveling wave generating electrodes 22 are arranged so that the microelectrodes 22 are parallel to each other with a spacing of 100 dpi (about 254 μm) to 300 dpi (about 85 μm). The microelectrodes 22 are formed as one set.
[0028]
The traveling wave generating electrodes 22 are arranged in almost the entire region in the length direction of the toner conveying member 13, and as shown in FIGS. 2 and 5, positions where they contact the supply member 17 and the recovery member 18 at both ends thereof. A toner supply area and a toner collection area in the vicinity are arranged.
[0029]
A three- or four-phase alternating voltage is applied to each set of electrodes 22, a traveling wave electric field is formed on the traveling wave generating electrode, and the toner is conveyed. The alternating voltage applied to the traveling wave generating electrodes is set to a value of, for example, about 10 V to 1 kV so that dielectric breakdown does not occur between the traveling wave generating electrodes, and the frequency is 100 Hz to 10 kHz based on the responsiveness of the toner. A value in the range is used.
[0030]
The values of the alternating voltage and the frequency may be set appropriately depending on the shape of the traveling wave generating electrode element, the toner transport speed, the toner material used, and the like. Further, as shown in FIG. 3, a DC voltage is applied to the toner conveying member 13 from a developing bias DC power source 20 so that a developing electric field is formed between the photosensitive member 1 and the toner conveying member 13. It has become.
[0031]
The toner conveying member 13 conveys toner by an electric field curtain action, and as shown in FIG. 3, a traveling wave generating electrode 22 for generating an electric field curtain action is formed as a set in the insulating layer 23. A plurality of sets are embedded successively. When a multiphase AC voltage is applied to these electrodes 22 from a multiphase AC power supply 19 for toner conveyance, an electric field curtain is generated in a direction parallel to the surface of the toner conveyance member 13, thereby developing the electrode. The toner is conveyed to the area by the electric field curtain action.
[0032]
Specific examples of the toner conveying member 13 include, for example, a base material 24 made of polyimide having a thickness of 25 μm, an insulating layer 23 in which a traveling wave generating electrode 22 made of copper having a thickness of 18 μm is embedded, and a polyimide having a thickness of 25 μm. A configuration in which the surface protective layer 25 made of is laminated from the lower layer to the upper layer can be given.
[0033]
Further, the traveling wave generating electrode 22 is a micro electrode having a width of 40 to 130 μm, and is arranged in parallel with each other at an interval of 100 dpi (dot per inch) to 300 dpi, that is, a pitch of about 254 μm to 85 μm. .
[0034]
In the present embodiment, four microelectrodes {circle around (1)} to {circle around (4)} as shown in FIG. 4 are set as one set, and four phases of voltage waveforms as shown in FIG. A traveling wave electric field is formed on the traveling wave generating electrode by applying an alternating voltage. However, the present invention is not limited to this, and a three-phase alternating voltage is applied to a set of three microelectrodes. It doesn't matter.
[0035]
Further, as shown in FIG. 3, it is preferable that a bias voltage (developing bias) is applied so that a developing electric field is formed between the photoreceptor 1 and the toner conveying member 13.
[0036]
The voltage waveform may be a sine wave or a trapezoidal wave, the voltage value range is preferably about 10 V to 1 kV, and the frequency range is preferably 100 Hz to 100 kHz. However, these voltage values and frequencies are not particularly limited as long as appropriate values are set according to the shape of the traveling wave generating electrode element, the toner conveyance speed, the toner used material, and the like.
[0037]
(Developer operation)
Next, the operation of the developing device 2 configured as described above will be described. The toner 15 held in the toner casing 12 is agitated by the MX paddle 14 rotating in the arrow B direction in FIG. 2, and the toner 15 is supplied in the vicinity of the supply member 17. The toner present in the vicinity of the supply member 17 is charged by the supply member 17 and supplied to the toner conveying member 13.
[0038]
The toner charged through the above process is transported in the direction of arrow a shown in FIG. 2 by a traveling wave electric field formed by the toner transport member 13, and is static on the photoreceptor in the development region (point facing the photoreceptor). Perform an electrostatic latent image. The toner that has not contributed to the development is further conveyed in the direction a, and returns again into the toner casing 12 via the recovery member 18.
[0039]
(Process after image formation)
In the developing device 2 using the traveling wave electric field, when the formation of the traveling wave electric field is completed at the same time after the development is completed, the toner remains on the toner conveying member 13 and the toner is conveyed when the time until the next development is long. The charge of the toner remaining on the member 13 is neutralized, and the charge amount may be insufficient.
[0040]
Therefore, in this embodiment, after the image formation is completed, the supply of toner from the supply member 17 is stopped, and the traveling wave electric field is applied for a certain period of time to prevent the generation of residual toner on the toner transport member. ing.
[0041]
Note that the predetermined time period during which the traveling wave electric field is applied is, for example, a time set at least longer than the time until the toner on the toner conveying member 13 is collected by the collecting member 18, and this time of the toner conveying member 13 It can be known from the length and toner conveyance speed.
[0042]
FIG. 5 is a diagram illustrating a configuration of a portion where the supply member 17 is disposed on the toner conveying member 13. As described above, the traveling wave generating electrode 22 of the toner conveying member 13 is disposed up to the toner supply region in the vicinity of the position in contact with the supply member 17. The supply member 17 facing the toner supply region is provided with a drive unit 30 such as a motor for rotating the supply member 17 and a control unit 31 for controlling the drive unit 30.
[0043]
The control unit 31 includes, for example, a CPU (Central Processing Unit), drives the drive unit 30 when receiving an image formation start signal, and stops driving of the drive unit 30 when receiving an image formation end signal.
[0044]
That is, when it is determined that the image formation has been completed, the driving of the supply member 17 is stopped, and the supply of toner from the supply member 17 to the toner transport member 13 is stopped. Accordingly, only the toner supplied onto the toner conveying member 13 at the time of image formation may be conveyed by the toner conveying member 13 and collected by the collecting member 18.
[0045]
As described above, in this embodiment, the toner supply is controlled by controlling the drive of the supply member 17 instead of operating the mechanical means such as the restriction plate as in the conventional case, and the toner is conveyed after the image formation is completed. The toner is prevented from remaining on the member 13.
[0046]
[Second Embodiment]
FIG. 6 is a configuration diagram of a toner supply region in which the supply member 17 is arranged on the toner conveying member 13 according to the second embodiment. In the present embodiment, in addition to the configuration shown in FIG. 5, voltage application means 32 for applying a voltage to the supply member 17 is provided, and the control means 31 controls the drive means 30 and the voltage application means 32. ing.
[0047]
The voltage application unit 32 applies a voltage having a polarity opposite to the charging polarity of the toner at least at the end of image formation to suppress the supply of toner from the supply member 17 to the toner transport member 13.
[0048]
Of course, during image formation, a voltage is applied between the toner conveying member 13 and the supply member 17 to control the charging of the toner and to control the amount of toner supplied from the supply member 17 to the toner conveying member 13. It doesn't matter.
[0049]
In this embodiment, when the control unit 31 receives an image formation end signal, a bias reverse to that at the time of image formation is applied to the voltage application unit 32 in order to prevent toner movement from the supply member 17 to the toner conveying member 13. For example, when the traveling wave electric field is set to 0 to −400 V, the supply member 17 may be set to be applied with −500 V at the time of image formation and +100 V at the end of image formation. Here, the charging polarity of the toner is negative.
[0050]
FIG. 7 shows an example of voltage waveforms applied to the toner conveying member 13 and the supply member 17 under the above conditions. Thus, only the toner supplied on the toner conveying member 13 may be conveyed and collected during image formation, and the toner can be prevented from remaining on the toner conveying member 13.
[0051]
In the above description, an example in which a voltage is applied to the supply member 17 by the voltage applying unit 32 at the time of image formation is shown, but the voltage is not applied at the time of image formation. May be controlled to apply a reverse voltage.
[0052]
This operation can be combined with the method of stopping the driving of the supply member 17 at the end of the image formation described in the first embodiment (see the broken line portion in FIG. 6), thereby more reliably image. The toner supply at the end of formation can be stopped.
[0053]
[Third Embodiment]
FIG. 8 is a configuration diagram of a toner supply region of the toner conveying member 13 according to the third embodiment. In this embodiment, after the image formation is completed, the traveling wave generating electrode 22 in the toner supply region 13a is controlled separately from the traveling wave generating electrodes in other regions in order to prevent the toner from remaining on the toner conveying member 13. It is configured as follows.
[0054]
That is, a switch 34 is provided in one unit composed of four traveling wave generating electrodes 22 in the toner supply region 13a, and this switch 34 is ON / OFF controlled by the control means 31, and the power from the multiphase AC power source 19 is supplied. It can be turned on and off. Note that the number of units provided with the switch 34 is not limited to one, but may be several units. In the above case, it is not necessary to divide the toner conveying member 13, and the object can be achieved by dividing the unit of the traveling wave generating electrode 22.
[0055]
The control of the switch 34 is to turn on the switch 34 at the time of image formation so that an electric field curtain is formed by the traveling wave generating electrode. After the image formation is completed, the switch is turned on the traveling wave generating electrode 22 in the toner supply region 13a. Turn off (0V) to stop voltage application.
[0056]
Thus, after the image formation is completed, the toner supplied from the supply member 17 is not conveyed to the toner conveyance member 13, and only the developer supplied onto the toner conveyance member at the time of image formation may be conveyed and collected. It is possible to prevent toner from remaining on the conveying member.
[0057]
This operation is appropriately combined with the method of stopping driving of the supply member 17 at the end of image formation and the method of applying a reverse bias to the supply member 17 described in the first and second embodiments. Accordingly, it is possible to prevent the toner from remaining on the toner conveying member 13 more reliably.
[0058]
[Fourth Embodiment]
FIG. 9 is a configuration diagram of a toner supply region of the toner conveying member 13 according to the fourth embodiment. In this embodiment, in addition to the configuration shown in FIG. 8, a multiphase AC voltage is applied to the traveling wave generating electrode 22 in the toner supply region 13a by another multiphase AC power source 35. The traveling wave generating electrode 22 in the region 13a is connected to the first multiphase AC power source 19 and the second multiphase AC power source 35, and a changeover switch 34 for switching the power supply from both the multiphase AC power sources 19 and 35 is provided. It has been.
[0059]
As shown in FIG. 10, the second multi-phase AC power source 35 has a multi-phase AC power supply that is in reverse phase to the image formation by the first multi-phase AC power source 19 after the end of image formation with respect to the electrode 22 in the toner supply region. A phase alternating voltage is applied.
[0060]
In the above configuration, at the end of image formation, a multi-phase AC voltage having a phase opposite to that at the time of image formation by the first multi-phase AC power source 19 is applied. The supply of toner from the supply member 17 to the toner transport member 13 is suppressed.
[0061]
At this time, since the multiphase AC voltage is applied from the first multiphase AC power supply 19 to the traveling wave generating electrode 22 in the other region, the toner on the toner conveying member 13 is the same as that at the time of image formation. It is conveyed in the direction and collected by the collecting member 18. Accordingly, it is possible to prevent toner from remaining on the toner conveying member 13.
[0062]
This operation can be combined with the method of stopping the driving of the supply member 17 at the end of the image formation described in the first embodiment, and as a result, the toner on the toner conveying member 13 remains more reliably. Can be prevented.
[0063]
[Fifth Embodiment]
FIG. 11 is a configuration diagram of a developing device including a covering member according to the fifth embodiment. In this embodiment, the toner conveying member 13 includes a covering member 40 that covers the peripheral surface and moves with respect to the toner conveying member 13. Even in such a configuration, the control on the supply member 17 and the control on the traveling wave generating electrode in the toner supply region shown in the first to fourth embodiments are applied to the toner conveying member 13 (on the covering member 40). The toner can be prevented from remaining.
[0064]
The covering member 40 has an endless belt shape, and is supported at least at three points by the toner conveying member 13 disposed on the support member 16, the driving roller 41, and the driven roller 42, and on the surface side of the toner conveying member 13. Closely arranged.
[0065]
The covering member 40 is driven by a driving roller 41 in the direction indicated by the arrow d in FIG. 11 at a speed that covers the peripheral surface of the toner conveying member 13 and is considered to be substantially stationary with respect to the toner conveying speed. It is used to prevent the toner conveying member 13 from being charged and to prevent the toner from sticking.
[0066]
The charge removal of the covering member 40 is performed by imparting electrical conductivity to the roller-shaped collection member 18 itself and having a charge removal function. Examples of the material of the covering member 40 include organic insulating materials such as polyimide, PET (polyethylene terephthalate), polytetrafluoroethylene, polyfluorinated ethylene propylene, and PTFE (polytetrafluoroethylene), and rubber materials such as silicon, isoprene, and butadiene. In addition, carbon black or an ionic conductive material is used that is dispersed or compatible with each other.
[0067]
The scraping member 43 disposed in contact with the covering member 40 is made of SUS (stainless steel), nickel-coated iron, urethane, silicon rubber, or the like, scraping off the toner remaining on the covering member 40, and is placed in the casing 12. It is something to return.
[0068]
The scraping member 43 is made of a material obtained by mixing a conductive agent such as carbon black or ions with urethane rubber or silicon, or a metal such as SUS (stainless steel) or nickel-coated iron. At the same time, the covering member 43 itself can be removed.
[0069]
In the configuration described above, except that the covering member 40 is provided in close contact with the toner conveying member 13, the scraping member 43 is disposed on the covering member 40, and the charge removing function is imparted to the collecting member 18, FIG. The same configuration as the developing device 2 shown in FIG. Therefore, by applying the methods shown in the first to fourth embodiments, the toner remaining on the covering member 40 can be collected after the image formation is completed.
[0070]
In addition, this invention is not limited to the said embodiment, Of course, many corrections and changes can be added within the scope of the present invention. For example, although the supply member 17 and the recovery member 18 are illustrated as roller-shaped in the above-described embodiment, the present invention is not limited to this, and the supply member 17 and the recovery member 18 are applicable regardless of the shape. Further, the supply member 17 and the recovery member 18 are not limited to those in contact with the toner conveying member 13, and may be those close to each other.
[0071]
【The invention's effect】
As is apparent from the above description, according to the present invention, at the end of image formation, the drive of the developer supply means is stopped, or a voltage having a polarity opposite to the charged polarity of the developer is applied to the developer supply means. By performing simple control, it is possible to prevent unnecessary supply of developer from the developer supply unit to the developer transport unit. Therefore, only the developer present on the developer conveying means at the end of image formation can be conveyed by the traveling wave electric field and quickly collected by the developer collecting means, and the developer remains on the developer conveying means. Can be suppressed.
[0072]
In addition, the configuration is such that the traveling wave generating electrode in the developer supply area of the developer conveying means is controlled separately from the traveling wave generating electrodes in the other areas, so that the vicinity where the developer supplying means abuts at the end of image formation. Supply of developer from developer supply means to developer transport means, such as by applying a multiphase AC voltage only to the traveling wave generation electrode or forming a traveling wave generation electric field in the opposite direction to that during image formation. Various methods can be applied to suppress this.
[0073]
Furthermore, in the image forming apparatus equipped with the developing device of the present invention, the developer on the developer conveying means is promptly collected at the end of image formation, so that the quality is such that fog or the like does not occur at the next development. A good image can be output and the scattering of the developer can be suppressed, so that an image forming apparatus with good maintainability can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus to which a developing device according to the present invention is applied.
FIG. 2 is a schematic configuration diagram of the developing device.
3 is a configuration diagram of a toner conveying member used in the developing device of FIG. 2;
4 is a diagram showing an example of a voltage waveform applied to the toner conveying member shown in FIG. 3;
FIG. 5 is a diagram illustrating a configuration example of a toner conveying member and a supply member according to the first embodiment of the present invention.
FIG. 6 is a diagram illustrating a configuration example of a toner conveying member and a supply member according to a second embodiment of the present invention.
7 is a diagram showing voltage waveforms applied to each member at the time of image formation and at the end of image formation in the toner supply region shown in FIG. 6;
FIG. 8 is a diagram illustrating a configuration example of a toner conveying member and a supply member according to a third embodiment of the present invention.
FIG. 9 is a diagram illustrating a configuration example of a toner conveying member and a supply member according to a fourth embodiment of the present invention.
10 is a diagram showing a voltage waveform applied to the toner conveying member shown in FIG. 9 at the end of image formation.
FIG. 11 is a configuration diagram of a developing device in which a covering member is provided on a peripheral surface of a toner conveying member according to a fifth embodiment of the present invention.
[Explanation of symbols]
1 Photoconductor
2 Development device
3 recording media
12 casing
13 Toner conveying member (developer conveying means)
13a Toner supply area
14 MX paddle (mixing means)
15 Toner
16 Support member
17 Supply member (developer supply means)
18 Recovery member (developer recovery means)
19 Multiphase AC power supply
20 Development bias DC power supply
22 Traveling wave generating electrode
23 Insulating layer
24 Substrate
25 Surface protective layer
30 Drive means
31 Control means
32 Voltage application means
34 switch
35 Second multiphase AC power supply
40 Covering member

Claims

A developing device for developing an electrostatic latent image formed on an image carrier, wherein a traveling wave electric field is formed by applying a multiphase AC voltage to a plurality of electrodes arranged at predetermined intervals, A developer conveying unit that conveys the developer toward the image carrier by the traveling wave electric field, and a developer that is disposed in contact with or close to the developer conveying unit and supplies the developer onto the developer conveying unit. A developer supplying means and a developer collecting means for collecting the developer that has not contributed to the development from the image carrier side into the developing casing, and the developer conveying means is formed in a semicircular arc shape or a planar shape, Disposed in the opening of the developing casing, the developer supplying means is disposed at one end of the developer conveying means, the developer collecting means is disposed at the other end of the developer conveying means, and the developer supplying means Control means for controlling the drive is provided It stops driving of the developing agent supply means at the time of image formation termination, and characterized in that collected by the developer collecting means and conveyed by the developer conveying means developer supplied onto the developer carrying means at the time of image formation Developing device.

A developing device for developing an electrostatic latent image formed on an image carrier, wherein a traveling wave electric field is formed by applying a multiphase AC voltage to a plurality of electrodes arranged at predetermined intervals, A developer conveying unit that conveys the developer toward the image carrier by the traveling wave electric field, and a developer that is disposed in contact with or close to the developer conveying unit and supplies the developer onto the developer conveying unit. A developer supplying means and a developer collecting means for collecting the developer that has not contributed to the development from the image carrier side into the developing casing, and the developer conveying means is formed in a semicircular arc shape or a planar shape, Disposed in the opening of the developing casing, the developer supplying means is disposed at one end of the developer conveying means, the developer collecting means is disposed at the other end of the developer conveying means, and the developer supplying means Applies voltage to developer supply means A pressure applying means and a control means for controlling the operation of the voltage applying means are provided, and at the end of image formation, the voltage applying means is controlled to apply a voltage having a polarity opposite to the charging polarity of the developer to the developer supplying means. The developing device is characterized in that the developer supplied onto the developer conveying means at the time of image formation is conveyed by the developer conveying means and collected by the developer collecting means .

A voltage is applied to the developer conveying means separately from the plurality of other electrodes of the developer conveying means with respect to the plurality of electrodes formed on the developer conveying means in a region facing the developer supplying means. There is provided a control means for controlling
At the end of image formation, the application of the multiphase AC voltage to the plurality of electrodes formed in the developer conveying means is stopped in the region of the developer conveying means facing the developer supplying means, and the developer conveying means 3. The developer according to claim 1, wherein the developer supplied onto the developer conveying unit at the time of image formation is conveyed by the developer conveying unit and collected by the developer collecting unit . Development device.

A voltage is applied to the developer conveying means separately from the plurality of other electrodes of the developer conveying means with respect to the plurality of electrodes formed on the developer conveying means in a region facing the developer supplying means. There is provided a control means for controlling
At the end of image formation, in a region where the developing agent supply means facing out of the developer conveying unit, a plurality of electrodes formed on the developer conveying unit, a traveling wave electric field in the opposite direction is formed at the time of image formation In this manner, a multi-phase AC voltage is applied, and the developer supplied on the developer conveying means at the time of image formation is conveyed by the developer conveying means in the other areas of the developer conveying means, and the developer collecting means The developing device according to claim 1, wherein the developing device is collected .

An image forming apparatus comprising the developing device according to claim 1 .