JP4391656B2

JP4391656B2 - An electrophotographic apparatus having an image carrier and a non-magnetic one-component developing device

Info

Publication number: JP4391656B2
Application number: JP2000046662A
Authority: JP
Inventors: 信隆野田; 健一田中; 浩人三角
Original assignee: Katsuragawa Electric Co Ltd
Current assignee: Katsuragawa Electric Co Ltd
Priority date: 2000-02-24
Filing date: 2000-02-24
Publication date: 2009-12-24
Anticipated expiration: 2020-02-24
Also published as: JP2001235943A

Description

【０００１】
本発明は電子写真装置に使用され、像担持体上に形成された静電潜像を非磁性一成分現像剤によって現像して可視化する非磁性一成分現像装置に関し、特には、常時一定のニップ幅で現像ローラを像担持体に押圧することが可能な像担持体と非磁性一成分現像装置を備えた電子写真装置に関する。
【０００２】
【従来の技術】
非磁性一成分現像剤を用いた現像装置の一例として、像担持体に現像剤を供給するための現像剤担持体として導電性のまたは適度な電気抵抗を有する弾性現像ローラを用い、該ローラの表面に現像剤の薄層を形成した後、該ローラを像担持体面に適宜な圧力で接触させて現像を行う接触型現像装置が提案されている。かかる非磁性一成分現像装置は、白黒２値で画像が構成されるようなデジタルプリンタなど、エッジ強調効果を必要とせず且つ線画像および面画像の現像特性が同一であることが要求されるような現像に好ましく使用できることが知られている。
【０００３】
非磁性一成分現像装置の一例として、像担持体に対する現像ローラの圧接力が比較的大きく且つ像担持体の周速度に対して現像ローラの周速度に差があるとその摺擦力により現像ローラ表面のトナーが粉砕され、トナー劣化が早まり、また、現像ローラ上に形成する現像剤層の厚さを規制する現像剤層規制部材の表面に、例えば数千ｍの現像で、トナーの固着（または融着）が生じ、この固着が現像剤薄層の均一な形成を妨げて画像に白筋を発生させる。また、周速を異にする現像ローラによる像担持体への圧接力の作用により、像担持体が回転ムラを生じ易いという欠点を有し、更には、大サイズの現像を行うための大型の電子写真装置においては、前記摺擦を生じさせるために現像ローラの駆動トルクがかなり大きくなり不経済となる。
【０００４】
このため本出願人は、上記問題点を解決するために、非磁性一成分トナーからなるトナー薄層を弾性現像ローラ上に形成し、該ローラをドラム状像担持体表面に当接させることにより像担持体表面に形成された静電潜像に弾性現像ローラ上の現像剤を供給して現像を行う現像装置において、像担持体の周速度と弾性現像ローラの周速度とがほぼ同速度となるように像担持体および弾性現像ローラを順方向に回転させ且つ弾性現像ローラの像担持体表面への食い込み量が現像ローラの半径の1/40以上となるように設定し、像担持体への弾性現像ローラの接触開始地点から接触離脱地点までの現像ニップ区間において弾性現像ローラの像担持体表面に接触する局部分の移動速度がローラ自体の弾性により接触開始地点から徐々に遅くなり、その後徐々に元の速度に回復しながら像担持体との接触から離脱するようにした非磁性一成分現像装置を提案した。
【０００５】
このような構成により、現像ローラの径のばらつきや偏心、環境変化により径の変化、像担持体の偏心等があっても充分な食い込みに設定される。像担持体周速と現像ローラの周速がほぼ同じ値で現像が行われるために像担持体の回転ムラが発生しない。像担持体に当接する現像ローラの食い込み量が大きく配置されるためにその変化が無視され、さらに現像ローラは半径の約1/40以上、好ましく1/20以上の食い込み量で設定する事により現像ローラ上のトナー層は像担持体表面周速に対し接触開始からそのほぼ接触中心点まで徐々に遅くなり、その後接触中心点から接触離点まで像担持体周速に戻る作用を行わせるために、現像作用とクリーニング作用とが同時に行われ非常にジッターのない鮮明な画像を形成することができる。特に、大サイズ現像においても白筋の発生や、カブリや濃度不足のない鮮明な画像を得ることができる。現像ローラの駆動トルクが少なくなり、現像ローラを像担持体に押圧する寸法精度が向上するという効果を有するものである。
【０００６】
【発明が解決しようとする課題】
上記した現像装置は像担持体と現像ローラとをほぼ同速度で回転させるようにしている。このため、像担持体と現像ローラとの駆動を別々に行った場合、双方の駆動の負荷変動により像担持体と現像ローラとの間で周速度のずれが生じジッターが発生するという問題を有する。また、同期信号により同時に駆動を行ってもそれぞれの駆動源の立ち上がり速度の差によりトルクが発生して異音や振動が発生するという問題を有する。
【０００７】
更に、上述した現像方式の現像ローラは、長時間にわたって画像形成を行わない場合に同一の場所で押圧され続けており、押圧されている弾性現像ローラの一部分が変形したり、現像ローラが押圧した部分の像担持体表面において帯電や転写など電気的にも影響を及ぼし、出力画像に悪影響を与えてしまうという問題を有する。
【０００８】
このため、カム機構などによって長時間使用しない場合においてタイマー制御や手動などにより現像装置を移動させて像担持体から現像ローラの押圧を開放している。このとき像担持体のギアと現像ローラのギアとが完全に離間してしまった場合、再度、現像ローラを像担持体に押圧させたときにそれぞれのギアの噛み合いがうまく噛み合わずにギアの先端同士がぶつかってしまいギアに負担が加わり、最悪の場合ギアが破損してしまうという問題を有する。
【０００９】
本発明は上記点に鑑みてなされたもので、上記した非磁性一成分現像装置の構成に加え、簡単な構成で安定した周速度を維持することができ、像担持体に押圧している現像ローラをギアが破損することなく接離することができる像担持体と非磁性一成分現像装置を備えた電子写真装置を提供するとこを課題とする。
【００１０】
【課題を解決するための手段】
上記問題を解決するために、本発明は、非磁性一成分トナーからなるトナー薄層を現像ローラ上に形成し、該ローラを像担持体表面に所定のニップ幅となるように当接させることにより像担持体表面に形成された静電潜像に現像ローラ上の現像剤を供給して現像を行う現像装置であって、且つ像担持体の周速度と現像ローラの周速度とがほぼ同速度となるように像担持体および現像ローラを順方向に回転させるように設定した非磁性一成分現像装置において、像担持体のフランジ部に設けたギアを現像ローラの端部に設けたギアに噛み合わせて像担持体からの駆動を現像装置に伝達させ、更に、現像ローラの両端側に設けた当接コロを像担持体の両端側に当接させてニップ幅を規制し、像担持体と現像ローラとが離間した状態のときに、再度の現像ローラの押圧により像担持体のフランジ部に設けたギアの先端と現像ローラの端部に設けたギアの先端とがぶつかることなく噛み合わせが可能なように、像担持体のギアと現像ローラのギアとがわずかに噛み合っていることを特徴とする。
【００１１】
また、前記弾性現像ローラが像担持体表面に接触するニップ幅が４mm以上であることを特徴とする。
【００１３】
【発明の実施の形態】
以下、本発明の好適な実施形態について図面を参照として説明する。
図１は、本発明が適用された現像装置の概略側面図であり、図２に概略上面図を示す。
図中、符号１は矢印Ａで示す方向、即ち時計方向に回転するドラム状の像担持体であり、例えば、アルミニウム等のドラム状基体の表面に電子写真感光体を備えた構成よりなる。感光体としては、ＯＰＣ感光体やアモルファスシリコン感光体等の周知の感光体が使用し得る。
【００１４】
図示していないが、像担持体１の周囲には、回転方向Ａに沿って像担持体の残留電荷を消去するためのイレーサランプ、像担持体を特定極性に一様に帯電する帯電器、帯電された像担持体表面にデジタル光情報を入射して像担持体上に静電潜像を形成させるＬＥＤヘッド等の露光装置、像担持体にトナーを供給して前記静電潜像を反転現像をして、即ち露光部分にトナーを付着させてトナー像を形成する現像装置２（図１）、像担持体上のトナー像を紙等の転写材上に転写させる転写装置が配置されている。これら像担持体周りの構成は現像装置２を除き周知のものを採択できる。
【００１５】
かかる配置において現像装置２は、例えば絶縁性非磁性一成分トナーからなる現像剤が収容された現像容器３と、弾性体からなる現像ローラ４と、現像ローラ４と適宜な圧力で接触して配置され現像ローラ４上に形成するトナー層厚を規制する層厚規制部材５と、現像ローラ４と接触して設けられ現像ローラ４にトナーを供給する供給ローラ６と、供給ローラ６の後方に配置された撹拌部材７などを備え、現像ローラ４、供給ローラ６、層厚規制部材５は、後述するように、適当なバイアス電源に接続されてそれぞれに所定のバイアス電圧が印加されている。なお、トナーは例えば反転現像のために、像担持体の帯電極性と同じ極性のトナーが使用される。
【００１６】
これら構成について詳述する。現像容器３内には所定量の非磁性一成分現像剤（以下、トナーという）が収容されており、像担持体１と対向する位置には、像担持体１の長さとほぼ等しい長さを有し、像担持体１の軸線と平行する方向に延びている現像ローラ４が、現像容器３に形成された開口８からその周面の一部を像担持体側に露出するようにして配置されている。現像容器３内のトナーの収容量は、図示していないが、供給ローラ６の頭が露出する程度の量とされ、常時に現像容器の後壁に設けたセンサーにより監視され、所定量以下となった時にはトナーカートリッジ９からトナーを補給すべく指示信号が発せられる。
【００１７】
現像ローラ４はステンレス等の導電性の剛体からなる中心軸１１の周りに弾性中間層１２を形成し、更に中間層１２の外周に弾性表面層１３を形成した構成よりなり、表面層１３、中間層１２が弾性変形をして４mm以上、好ましくは５〜１０mmのニップ幅で像担持体１の表面に圧接するように配置され、像担持体１の回転と順方向に、即ち反時計方向Ｂに回転するようになっている。
【００１８】
先に述べたように、現像ローラ４の中心軸１１はスイッチ２１を介してバイアス電源１４ａに接続されている。バイアス電源１４ａは、静電潜像を現像し画像背景部（バックグランド）へのトナーのかぶりを防止するためのバイアス電圧を印加する。かかるバイアス電圧は、像担持体１の表面帯電位よりも絶対値で１００〜５００Ｖ、好ましくは３００〜４００Ｖ低い値に設定されている。かかる電位差が３００Ｖ以下の場合には現像濃度が濃くなり、４００Ｖ以上になると現像濃度が低下するという傾向がある。なお、図示例ではバイアス電源１４ａとは正負逆極性の第２のバイアス電源１４ｂを備えており、前記したスイッチ３１の切り換えにより、いずれかのバイアス電源への接続が行われる。この切り換えは、現像ローラ４が主として現像に寄与する画像形成時と、例えば画像形成前、または画像形成と画像形成との間のアイドリング中など主としてクリーニングに寄与する時とに依り所定のタイミングで切り換えられ、即ち、現像時には像担持体１の表面の帯電電位と同極性に、非帯電時には像担持体１の表面の帯電電位と逆極性になるように行われる。
【００１９】
再び現像ローラ４の構成に戻ると、中心軸１１の外側に形成されている中間層１２とその外周に形成されている表面層１３とは、例えば中間層１２が比較的高抵抗であり、表面層１３が相対的に低抵抗であるような体積抵抗値を持つ異なる性質を持つシリコンゴムからなる２層の弾性体により形成される。例えば、中間層１２を構成するシリコンゴムは１０^４〜１０^９Ω・cmの体積抵抗、表面層１３を構成するシリコンゴムは１０^５〜１０^６Ω・cmの体積抵抗値を有するものが好ましい。現像ローラ４としては、かかる二層構造に限定されることなく、単層の構造であっても良く、逆に三層以上の構造であっても良い。また材料としては、シリコンゴムの他、中間層１２としてＮＢＲゴム（アクリロニトリルブタジエン共重合ゴム）やウレタンゴム等の弾性を有する多孔質発泡体からなるものを使用し、表面層１３もウレタンゴム等の弾性体で形成したものを使用しても良い。
また、ＮＢＲゴム、ウレタンゴム、シリコンゴムなどの単層タイプであっても良い。
【００２０】
これら単層の現像ローラの弾性層または多層の現像ローラの中間層および表面層からなる弾性層の比抵抗は１０^５〜１０^８Ω・cmの範囲内が好ましく、またゴム硬度は２０〜３０度程度の範囲のものが好ましく、特には表面層１３はトナー搬送力を得るめに微小な凹凸を表面に有し且つトナーとの離型性が良く、トナーに対して摩擦帯電系列が離れた材料によって形成されることが望ましい。
【００２１】
現像ローラ４の表面はトナーの粒径により異なるが、トナー平均粒径が８〜１０μｍ程度の場合は、約１０μｍの凹凸を有することが好ましく、中間層に約１０〜２０度程度の低い硬度のものを用い、表面層に２０〜３０度程度の硬度の弾性体を用い、かかる現像ローラを、像担持体１に対して食い込み量が現像ローラ４の半径の1/40倍（2.5％）、好ましくは1/20倍（５％）以上となるように配置し、像担持体１の周速度とほぼ同じ周速度で回転して現像を行う。ここで重要なことは表面層１３の凹凸の粗さと現像ローラ４の表面みかけ硬度であり、現像ローラの表面みかけ硬度が低硬度である方が回転トルクが小さく好ましい。
【００２２】
現像ローラ４の後方に位置する供給ローラ６は、現像ローラ４の軸線と平行に延びて配置され、現像ローラ４とほぼ全長にわたって接触している。供給ローラ６は、例えばカーボン微粉末が混入されたウレタンゴムの発泡体からなり、現像ローラ４に対して所定の圧力で接触しながら現像ローラ４の回転方向とは対向する方向、即ち反時計方向に回転し、現像容器３内のトナーを現像ローラ４に供給すると共に、摩擦帯電により現像ローラ４上のトナーを荷電する。現像ローラ４や供給ローラ６との摩擦によるトナーの帯電は現像品質に大きく影響し、帯電が不足した場合には、カブリや濃度ムラが発生する。
【００２３】
供給ローラ６の中心軸１６はツェナーダイオード（図示なし）を介してバイアス電源１４ｃに接続されており所定のバイアス電圧が印加されている。かかる供給ローラ６へ印加されるバイアス電位は、現像ローラ４のバイアス電位よりも絶対値で１００〜５００Ｖ高い電位に設定されており、この電位差によりトナーを供給ローラ６から現像ローラ４へと移転させる。
【００２４】
供給ローラ６の後方に設けられた撹拌部材７は、現像ローラ４の軸線と同方向に延びる中心軸１８と、該軸に軸線方向の複数箇所において設けられた複数の撹拌翼１９を有し、その回転により現像容器３内のトナーを撹拌すると共にトナーを供給ローラ６へと搬送し供給する。この例では撹拌翼１９は時計方向に回転している。
【００２５】
供給ローラ６により現像ローラ４上に層状に供給されたトナーは層厚規制部材５によりその層厚が規制される。層厚規制部材５は、現像ローラ４の回転方向で見て、現像ローラ４と像担持体１との接触部、即ち現像ニップ区間の上流位置に配置された導電性または半導電性のローラ体からなり、現像ローラ４とほぼ同じ長さを有し、現像ローラ４の全長にわたって、その周面の一部が現像ローラ４の表面層に対し所定の圧力で接触しながら回転するように設けられている。図示例では層厚規制部材５は現像ローラ４の直上位置に配置されている。層厚規制部材５には前出の供給ローラ６と同極性のバイアスが印加されている。
【００２６】
層厚規制部材５は現像ローラ４の回転方向Ｂと対向する方向、即ち反時計方向に回転し、現像ローラ４上に付着したトナーの一部を現像ローラ４に薄層（トナーの１〜３層）分だけを残すように、その他のトナーをその周面に転写吸着して除去するように働く。こうして層厚規制部材５により剥ぎ取られ転写された余剰のトナーは、層厚規制部材５の周面と先端が当接するようにして配置された弾性除去ブレード２１により層厚規制部材５から除去される。
【００２７】
更に、図２に示すように上述した現像装置の構成に加え、像担持体１を回転中心に保持するフランジ１０と、一方のフランジ１０に設けられたギア１５ａと、現像ローラ４の回転軸の一端側に支持されたギア１５ｂと、現像ローラ４の中心軸１１に支持された当接コロ１７とを有する。
フランジ１０は筒状の像担持体１を軸中心に回転駆動するように設けられ、不図示の駆動源により連結されている。
当接コロ１７は樹脂製あるいは金属製の円盤形状をしており、現像ローラ４の中心軸１１の両端側に自由回転可能に設けられ、現像ローラ４が像担持体１に向かって押圧する量を規制し、像担持体１の端部あるいはフランジ１０に当接して回転する。こうして当接コロが像担持体に当接したときには現像ローラが所定のニップ幅となる。現像装置２の移動は、後述するカムが現像装置を像担持体に向かって当接コロが像担持体あるいはフランジに当接するまで付勢するように設けられている。
【００２８】
符号２０は現像装置２を像担持体１に対して接離する機能を備えたカムを示し、例えば、現像装置２の一部に当接して電源の投入時に回動して現像ローラ４を像担持体１に押圧させるカム２０を有し、電源を投入されているときに充電するようにコンデンサを設け、電源を切断したときにコンデンサが電源となるように切り替わってカム２０を回動させて現像装置２を像担持体１から離れる方向に移動させるように設けられている。
【００２９】
装置本体の電源を投入すると、カム２０の外周面が現像装置の一部に当接する位置が最少半径の位置から最大半径の位置の近傍となるまで回動し、除々に現像装置２を像担持体１方向に移動させ、所定のニップ幅となるまで現像ローラ４を像担持体１に押圧する。
次いで図３に示すように電源を切断したときにリレーなどによりコンデンサがカムを駆動させる駆動手段に接続するように切り替わり、コンデンサに充電された電気により駆動手段を駆動させ、最大半径の近傍の位置から最少半径の位置までカムを所定の角度回動させる。カム２０の回動により、カムの段差を通って瞬時に現像装置が像担持体から離れる方向に移動して現像ローラの押圧力が緩和あるいは離間される。
【００３０】
上記カム２０の動作により現像装置２を像担持体１に移動させ、現像ローラ４が所定のニップ幅となるように像担持体１に押圧したときに像担持体１に設けたギア１５ａと現像ローラ４に設けたギア１５ｂとが噛み合って駆動伝を行うことができる。また、現像装置２を像担持体１から離れる方向に移動して現像ローラ４の押圧力が緩和あるいは離間したとき、像担持体１のギア１５ａと現像ローラ４のギア１５ｂとは完全に離間せずに、ギアの先同士で駆動は伝達することができないがわずかに噛み合わさっている。これにより再度の現像ローラ４の押圧によりギア１５ａ、１５ｂの先端同士がぶつかることなく噛み合わせを行うことができる。
【００３１】
次に、動作について説明すると、まず像担持体１が矢印Ａ方向に回転している状態において、像担持体１に残留していた残留電位がイレーサランプより除去され、次いでコロナ帯電器または帯電ローラ等の帯電器により像担持体面が一様に帯電される。続いて露光装置によりデジタル露光が行われて、像担持体１上に静電潜像が形成される。該潜像は像担持体１の回転により現像装置２の現像ローラ４と接触する位置、即ち現像ニップ区間へと搬送される。
【００３２】
一方、現像装置２では、像担持体１の回転とほぼ同時に、現像ローラ４、供給ローラ６、撹拌部材７が図示しない駆動源によりそれぞれの矢印で示した方向に回転し、且つ現像ローラ４、供給ローラ６および層厚規制部材５にはそれぞれ所定のバイアス電圧が印加される。
【００３３】
撹拌部材７および供給ローラ６の回転により、現像容器３内のトナーが撹拌され且つ供給されて現像ローラ４上にトナー層が形成される。トナー層は層厚規制部材５により１〜３層のトナーの均一な薄層となるように規制された後、現像ローラの回転に伴い現像ニップ区間に運ばれる。
【００３４】
この薄層化されたトナーは現像ニップ区間において像担持体の静電潜像に供給され、吸引付着することで現像が行われ、可視トナー像が形成される。
【００３５】
トナー像は像担持体１の回転により図示しない転写領域まで搬送され、ここで転写コロナまたは転写ローラ等の転写装置の作用により転写材の背面側からトナーの極性とは反対の極性の電界が付与されてトナーの転写材上への転写が行われ、転写されたトナー像は図示しない定着部で転写材上に定着される。一方、転写材に転写されない像担持体上の残留トナーはイレーサにより全面露光を受けて像担持体の暗部電位（画像背景部の電位）とほぼ同電位となるようにされ、次いで上記したと同様に次の作像のための帯電、露光を受け、再び現像ローラ４に運ばれる。現像ローラ４は像担持体１上に残留しているトナーを現像装置２へと回収すると共に、新しいトナーを像担持体１の表面に提供して次の潜像を現像する。
【００３６】
Ａ０サイズ対応の直径１２０mm、長さ約９３０mmのＯＰＣ感光体からなる像担持体１と、直径４０mm、長さ約９３０mmの表面みかけ硬度２５〜３５度、体積固有抵抗約３×１０^６Ω・cmの表面粗さ約１０μｍの現像ローラ４を用い、現像ローラ４の像担持体１への食い込み量が約０．５〜３mm（現像ローラの半径の1/40〜3/20倍）、現像ニップ幅（現像ニップ区間）が３．５〜１０mmになるようにカムの押圧により現像ローラに設けた当接コロが像担持体に当接させて現像ローラ４を所定のニップ幅となるように配置し、像担持体の駆動力を現像ローラにギアにより伝達させて現像ローラ４を像担持体１と順方向に像担持体１の周速度とほぼ同じ周速度、約２００mm/secで回転させた。供給ローラ６としては体積固有抵抗５×１０^４Ω・cmのスポンジローラを用いた。現像ローラ４に２５０〜３５０Ｖ、体積固有抵抗５×１０^４Ω・cmの供給ローラ６に約３５０Ｖ〜５５０Ｖのバイアスを印加し、供給ローラ６で現像ローラ４に平均粒径８μｍのトナーを塗布した後、層厚規制部材５で現像ローラ４上の層厚がトナー平均粒径の１〜３倍となるようにトナー層を形成し、暗部電位約５５０Ｖ〜６５０Ｖ、明部電位約２０Ｖの静電潜像を形成した像担持体１にこれを接触させて現像を行い、次いで、転写材に転写し、定着して良好な最終画像を得た。
【００３７】
この現像過程において現像ローラ４の接触開始地点から接触離脱地点までの現像ニップ区間においては、現像ローラ４の像担持体１の表面に接触する局部分の移動速度は、接触開始地点では像担持体１の周速度とほぼ同じであるが、現像ローラ４自体の弾性により且つ像担持体１に対する現像ローラ４を上記食い込みにより現像ニップ区間における現像ローラの局部の半径が変化することにより、局部分の移動速度が徐々に像担持体周速より遅くなり、その後徐々に元の速度に回復しながら像担持体との接触から離脱するように動作すると考えられる。
【００３８】
なお、上記した現像ニップ区間での現像ローラの局部分の動作は、像担持体上の残留トナーのクリーニングに関しても良好な作用をなし、即ち、像担持体１の残留トナーに対し上記のように移動速度を変化させる局部分の動作と現像ローラ表面の凹凸とによりトナーを除去するためのブレード効果が生じて良好なクリーニングがなされるものと考えられる。
【００３９】
更に、上記例に示すように像担持体と現像ローラが接触式である場合、抵抗値が低過ぎるとリークする関係上、トナーは、限定されるものではないが、重合トナーであって１０^６Ω・cm以上の高抵抗または絶縁性のものが用いられ、特には、粒径が５〜８μｍの球形で且つ帯電量が５０μC/ｇ以上のものが好ましい。
【００４０】
【発明の効果】
以上、本発明によれば、現像ローラを当接コロで像担持体に所定のニップ幅となるように押圧する非磁性一成分現像装置において、像担持体の駆動を現像ローラにギアにより伝達することにより画像のぶれがなくなり、安定した画像を得ることができる。また、現像装置の不使用時に現像装置を像担持体に対して離れる方向に移動させ、像担持体のギアと現像ローラのギアとを完全に離れないようにわずかに噛み合わせた状態にすることにより再度の現像装置の押圧によりスムーズにギアが噛み合い破損することがない。
【図面の簡単な説明】
【図１】本発明による現像装置の好適な一例を示す概略側面図。
【図２】本発明による現像装置の概略上面図。
【図３】現像装置が像担持体から離れる方向に移動した状態を示す概略側面図。
【符号の説明】
１像担持体
２現像装置
３現像容器
４現像ローラ
５層厚規制部材
６供給ローラ
７撹拌部材
８開口
９トナーカートリッジ
１０フランジ
１１中心軸
１２中間層
１３表面層
１４ａ、ｂバイアス電源
１５ａ、ｂギア
１６中心軸
１７当接コロ
１８中心軸
１９撹拌翼
２０カム
２１スイッチ[0001]
The present invention relates to a non-magnetic one-component developing device that is used in an electrophotographic apparatus and develops and visualizes an electrostatic latent image formed on an image carrier with a non-magnetic one-component developer. The present invention relates to an electrophotographic apparatus including an image carrier capable of pressing a developing roller against the image carrier with a width and a non-magnetic one-component developing device .
[0002]
[Prior art]
As an example of a developing device using a non-magnetic one-component developer, an elastic developing roller having a conductive or moderate electric resistance is used as a developer carrying member for supplying the developer to the image carrying member. There has been proposed a contact-type developing device in which development is performed by forming a thin layer of developer on the surface and then bringing the roller into contact with the surface of the image carrier at an appropriate pressure. Such a non-magnetic one-component developing device does not require an edge enhancement effect such as a digital printer in which an image is composed of black and white binary values, and the development characteristics of the line image and the surface image are required to be the same. It is known that it can be preferably used for such development.
[0003]
As an example of a non-magnetic one-component developing device, if the pressing force of the developing roller against the image carrier is relatively large and there is a difference in the peripheral speed of the developing roller with respect to the peripheral speed of the image carrier, the developing roller is caused by the rubbing force The toner on the surface is pulverized, the toner deterioration is accelerated, and the toner adheres to the surface of the developer layer regulating member that regulates the thickness of the developer layer formed on the developing roller by developing, for example, several thousand meters ( (Or fusion) occurs, and this fixation prevents uniform formation of the developer thin layer and causes white streaks in the image. Further, due to the action of the pressure contact force on the image carrier by the developing rollers having different peripheral speeds, the image carrier is liable to cause rotation unevenness, and further, a large size for carrying out a large size development. In the electrophotographic apparatus, the driving torque of the developing roller is considerably increased to cause the rubbing, which is uneconomical.
[0004]
Therefore, in order to solve the above problems, the present applicant forms a toner thin layer made of non-magnetic one-component toner on the elastic developing roller, and makes the roller contact the surface of the drum-shaped image carrier. In a developing device that performs development by supplying a developer on an elastic developing roller to an electrostatic latent image formed on the surface of an image carrier, the peripheral speed of the image carrier and the peripheral speed of the elastic developer roller are substantially the same. Rotate the image carrier and the elastic developing roller in the forward direction so that the amount of biting of the elastic developing roller into the surface of the image carrier is 1/40 or more of the radius of the developing roller. In the development nip section from the contact start point of the elastic developing roller to the contact detachment point, the moving speed of the local portion that contacts the surface of the image carrier of the elastic developing roller gradually decreases from the contact start point due to the elasticity of the roller itself. Xu A non-magnetic one-component developing device has been proposed in which the original speed is restored while being removed from contact with the image carrier.
[0005]
With such a configuration, even if there is a variation or eccentricity of the diameter of the developing roller, a change in diameter due to environmental changes, an eccentricity of the image carrier, etc., sufficient biting is set. Since the development is performed with the peripheral speed of the image carrier and the peripheral speed of the developing roller being substantially the same value, uneven rotation of the image carrier does not occur. Since the amount of biting of the developing roller in contact with the image carrier is large, the change is ignored, and further, the developing roller is developed by setting the biting amount to about 1/40 or more, preferably 1/20 or more of the radius. The toner layer on the roller gradually slows down from the contact start to the contact center point with respect to the image carrier surface peripheral speed, and then returns to the image carrier peripheral speed from the contact center point to the contact separation point. The developing action and the cleaning action are performed at the same time, and a clear image with very little jitter can be formed. In particular, it is possible to obtain a clear image free from white streaks, fogging, and insufficient density even in large-size development. The driving torque of the developing roller is reduced, and the dimensional accuracy for pressing the developing roller against the image carrier is improved.
[0006]
[Problems to be solved by the invention]
The developing device described above rotates the image carrier and the developing roller at substantially the same speed. For this reason, when the image carrier and the developing roller are driven separately, there is a problem in that a deviation in peripheral speed occurs between the image carrier and the developing roller due to load fluctuations of both driving, and jitter occurs. . Further, even if driving is performed simultaneously by the synchronization signal, there is a problem that torque is generated due to a difference in rising speeds of the respective driving sources, and abnormal noise and vibration are generated.
[0007]
Further, the development type developing roller described above continues to be pressed at the same place when image formation is not performed for a long time, and a part of the pressed elastic developing roller is deformed or the developing roller is pressed. There is a problem that the surface of a part of the image carrier has an electrical influence such as charging and transfer, and adversely affects the output image.
[0008]
Therefore, when the cam mechanism is not used for a long time, the developing device is moved by timer control or manual operation to release the pressure of the developing roller from the image carrier. At this time, if the gear of the image carrier and the gear of the developing roller are completely separated from each other, when the developing roller is pressed against the image carrier again, the meshing of each gear does not mesh well, and the tip of the gear They collide with each other and put a burden on the gear, and in the worst case, the gear is damaged.
[0009]
The present invention has been made in view of the above points. In addition to the above-described configuration of the non-magnetic one-component developing device, the developing device can maintain a stable peripheral speed with a simple configuration and is pressed against the image carrier. It is an object of the present invention to provide an electrophotographic apparatus including an image carrier and a non-magnetic one-component developing device that can contact and separate the rollers without damaging the gears.
[0010]
[Means for Solving the Problems]
In order to solve the above problem, the present invention forms a toner thin layer made of nonmagnetic one-component toner on a developing roller , and makes the roller abut on the surface of the image carrier so as to have a predetermined nip width. The developing device supplies the developer on the developing roller to the electrostatic latent image formed on the surface of the image bearing member for development, and the peripheral speed of the image bearing member and the circumferential speed of the developing roller are substantially the same. In a non-magnetic one-component developing device set so that the image carrier and the developing roller are rotated in the forward direction so as to achieve speed, the gear provided at the flange portion of the image carrier is changed to the gear provided at the end of the developing roller. The drive from the image carrier is transmitted to the developing device by meshing, and the contact rollers provided on both ends of the developing roller are brought into contact with both ends of the image carrier to regulate the nip width. When the developer roller is separated from the developing roller, As the tip of the gear provided by the pressure of the developing roller to the flange portion of the image bearing member and the tip of the gear provided at an end portion of the developing roller capable engagement without hits, gear and the developing roller of the image carrier It is characterized by slightly meshing with the gear.
[0011]
Further, the nip width at which the elastic developing roller contacts the surface of the image carrier is 4 mm or more.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
FIG. 1 is a schematic side view of a developing device to which the present invention is applied, and FIG. 2 shows a schematic top view.
In the figure, reference numeral 1 denotes a drum-shaped image carrier that rotates in the direction indicated by the arrow A, that is, clockwise, and has a configuration in which an electrophotographic photosensitive member is provided on the surface of a drum-shaped substrate such as aluminum. As the photoreceptor, a known photoreceptor such as an OPC photoreceptor or an amorphous silicon photoreceptor can be used.
[0014]
Although not shown, around the image carrier 1, there are an eraser lamp for erasing residual charges of the image carrier along the rotation direction A, a charger for uniformly charging the image carrier to a specific polarity, An exposure device such as an LED head that makes digital light information incident on the surface of the charged image carrier to form an electrostatic latent image on the image carrier, and inverts the electrostatic latent image by supplying toner to the image carrier. A developing device 2 (FIG. 1) that develops, that is, attaches toner to the exposed portion to form a toner image, and a transfer device that transfers the toner image on the image carrier onto a transfer material such as paper are arranged. Yes. As the configuration around the image carrier, a well-known configuration can be adopted except for the developing device 2.
[0015]
In such an arrangement, the developing device 2 is arranged in contact with the developing container 3 containing a developer made of, for example, insulating non-magnetic one-component toner, the developing roller 4 made of an elastic body, and the developing roller 4 with an appropriate pressure. A layer thickness regulating member 5 that regulates the thickness of the toner layer formed on the developing roller 4, a supply roller 6 that is provided in contact with the developing roller 4 and supplies toner to the developing roller 4, and disposed behind the supply roller 6. The developing roller 4, the supply roller 6, and the layer thickness regulating member 5 are connected to an appropriate bias power source and a predetermined bias voltage is applied to each, as will be described later. For example, a toner having the same polarity as the charging polarity of the image carrier is used for reversal development.
[0016]
These configurations will be described in detail. A predetermined amount of non-magnetic one-component developer (hereinafter referred to as toner) is accommodated in the developing container 3, and a length substantially equal to the length of the image carrier 1 is provided at a position facing the image carrier 1. A developing roller 4 that extends in a direction parallel to the axis of the image carrier 1 is disposed so that a part of its peripheral surface is exposed to the image carrier side from an opening 8 formed in the developing container 3. ing. The amount of toner contained in the developing container 3 is not shown, but is such an amount that the head of the supply roller 6 is exposed, and is constantly monitored by a sensor provided on the rear wall of the developing container, and is below a predetermined amount. When this happens, an instruction signal is issued from the toner cartridge 9 to replenish the toner.
[0017]
The developing roller 4 has a configuration in which an elastic intermediate layer 12 is formed around a central axis 11 made of a conductive rigid body such as stainless steel, and an elastic surface layer 13 is formed on the outer periphery of the intermediate layer 12. The layer 12 is elastically deformed and is arranged so as to come into pressure contact with the surface of the image carrier 1 with a nip width of 4 mm or more, preferably 5 to 10 mm, and rotates in the forward direction, that is, counterclockwise B. It is designed to rotate.
[0018]
As described above, the central shaft 11 of the developing roller 4 is connected to the bias power source 14a via the switch 21. The bias power source 14a applies a bias voltage for developing the electrostatic latent image and preventing the toner from being fogged to the image background (background). Such a bias voltage is set to an absolute value lower than the surface charging position of the image carrier 1 by 100 to 500 V, preferably 300 to 400 V. When the potential difference is 300 V or less, the development density tends to be high, and when the potential difference is 400 V or more, the development density tends to decrease. In the illustrated example, the bias power source 14a includes a second bias power source 14b having a polarity opposite to that of the bias power source 14a, and connection to any bias power source is performed by switching the switch 31 described above. This switching is performed at a predetermined timing depending on whether the developing roller 4 mainly contributes to development and when it contributes mainly to cleaning, for example, before image formation or during idling between image formation and image formation. That is, it is carried out so that it has the same polarity as the charged potential of the surface of the image carrier 1 during development, and has the opposite polarity to the charged potential of the surface of the image carrier 1 when uncharged.
[0019]
When returning to the configuration of the developing roller 4 again, the intermediate layer 12 formed on the outer side of the central shaft 11 and the surface layer 13 formed on the outer periphery thereof are, for example, the intermediate layer 12 having a relatively high resistance. The layer 13 is formed by a two-layered elastic body made of silicon rubber having different properties having a volume resistance value that is relatively low resistance. For example, the silicon rubber constituting the intermediate layer 12 preferably has a volume resistance of 10 ⁴ to 10 ⁹ Ω · cm, and the silicon rubber constituting the surface layer 13 preferably has a volume resistance of 10 ⁵ to 10 ⁶ Ω · cm. The developing roller 4 is not limited to such a two-layer structure, and may be a single-layer structure, or conversely, may have a structure of three or more layers. In addition to silicon rubber, the intermediate layer 12 is made of an elastic porous foam such as NBR rubber (acrylonitrile butadiene copolymer rubber) or urethane rubber, and the surface layer 13 is also made of urethane rubber or the like. You may use what was formed with the elastic body.
Further, it may be a single layer type such as NBR rubber, urethane rubber, or silicon rubber.
[0020]
The specific resistance of the elastic layer of the single layer developing roller or the elastic layer composed of the intermediate layer and the surface layer of the multilayer developing roller is preferably in the range of 10 ⁵ to 10 ⁸ Ω · cm, and the rubber hardness is 20 to 30 degrees. In particular, the surface layer 13 is a material having fine irregularities on the surface for obtaining a toner conveyance force, good releasability from the toner, and a triboelectric charge series away from the toner. It is desirable to be formed by.
[0021]
The surface of the developing roller 4 varies depending on the particle size of the toner, but when the average particle size of the toner is about 8 to 10 μm, it is preferable to have irregularities of about 10 μm, and the intermediate layer has a low hardness of about 10 to 20 degrees. The surface layer is made of an elastic body having a hardness of about 20 to 30 degrees, and the developing roller bites into the image carrier 1 by 1/40 times (2.5%) the radius of the developing roller 4; It is preferably arranged so as to be 1/20 times (5%) or more, and development is carried out by rotating at substantially the same peripheral speed as that of the image carrier 1. What is important here is the roughness of the unevenness of the surface layer 13 and the surface apparent hardness of the developing roller 4, and the lower the surface apparent hardness of the developing roller, the smaller the rotational torque.
[0022]
The supply roller 6 located behind the developing roller 4 is disposed so as to extend in parallel with the axis of the developing roller 4 and is in contact with the developing roller 4 over almost the entire length. The supply roller 6 is made of, for example, urethane rubber foam mixed with fine carbon powder, and is in a direction opposite to the rotation direction of the developing roller 4 while contacting the developing roller 4 with a predetermined pressure, that is, counterclockwise. The toner in the developing container 3 is supplied to the developing roller 4, and the toner on the developing roller 4 is charged by frictional charging. The charging of the toner due to friction with the developing roller 4 and the supply roller 6 greatly affects the development quality. If the charging is insufficient, fogging and density unevenness occur.
[0023]
The central axis 16 of the supply roller 6 is connected to a bias power source 14c via a Zener diode (not shown), and a predetermined bias voltage is applied. The bias potential applied to the supply roller 6 is set to an absolute value 100 to 500 V higher than the bias potential of the developing roller 4, and toner is transferred from the supply roller 6 to the developing roller 4 by this potential difference. .
[0024]
The stirring member 7 provided behind the supply roller 6 has a central shaft 18 extending in the same direction as the axis of the developing roller 4, and a plurality of stirring blades 19 provided on the shaft at a plurality of locations in the axial direction. The rotation stirs the toner in the developing container 3 and conveys and supplies the toner to the supply roller 6. In this example, the stirring blade 19 rotates in the clockwise direction.
[0025]
The layer thickness of the toner supplied in layers on the developing roller 4 by the supply roller 6 is regulated by the layer thickness regulating member 5. The layer thickness regulating member 5 is a conductive or semi-conductive roller body disposed at a contact portion between the developing roller 4 and the image carrier 1, that is, at an upstream position in the developing nip section when viewed in the rotation direction of the developing roller 4. And has a length substantially the same as that of the developing roller 4, and is provided so that a part of the peripheral surface of the developing roller 4 rotates while contacting the surface layer of the developing roller 4 with a predetermined pressure over the entire length of the developing roller 4. ing. In the illustrated example, the layer thickness regulating member 5 is arranged at a position immediately above the developing roller 4. A bias having the same polarity as that of the supply roller 6 is applied to the layer thickness regulating member 5.
[0026]
The layer thickness regulating member 5 rotates in a direction opposite to the rotation direction B of the developing roller 4, that is, in a counterclockwise direction, and a part of the toner adhering to the developing roller 4 is thinly layered on the developing roller 4. The remaining toner is transferred and adsorbed to the peripheral surface so as to leave only the layer). Excess toner thus peeled off and transferred by the layer thickness regulating member 5 is removed from the layer thickness regulating member 5 by the elastic removing blade 21 arranged so that the peripheral surface and the tip of the layer thickness regulating member 5 are in contact with each other. The
[0027]
Further, in addition to the configuration of the developing device described above as shown in FIG. 2, the flange 10 that holds the image carrier 1 at the center of rotation, the gear 15 a provided on one flange 10, and the rotating shaft of the developing roller 4. A gear 15 b supported on one end side and a contact roller 17 supported on the central shaft 11 of the developing roller 4 are provided.
The flange 10 is provided so as to rotationally drive the cylindrical image carrier 1 about its axis, and is connected by a drive source (not shown).
The contact roller 17 has a disk shape made of resin or metal, is provided on both ends of the central shaft 11 of the developing roller 4 so as to be freely rotatable, and an amount by which the developing roller 4 is pressed toward the image carrier 1. And rotates in contact with the end of the image carrier 1 or the flange 10. Thus, when the contact roller contacts the image carrier, the developing roller has a predetermined nip width. The movement of the developing device 2 is provided such that a cam described later urges the developing device toward the image carrier until the contact roller contacts the image carrier or the flange.
[0028]
Reference numeral 20 denotes a cam having a function of bringing the developing device 2 into and out of contact with the image carrier 1. For example, the cam 20 abuts against a part of the developing device 2 and rotates when the power is turned on to move the developing roller 4 to the image. The cam 20 is pressed against the carrier 1, and a capacitor is provided so as to be charged when the power is turned on. When the power is turned off, the capacitor is switched to the power source and the cam 20 is rotated. The developing device 2 is provided to move in a direction away from the image carrier 1.
[0029]
When the power of the apparatus main body is turned on, the position where the outer peripheral surface of the cam 20 abuts on a part of the developing device is rotated from the position of the minimum radius to the vicinity of the position of the maximum radius, and the image forming apparatus 2 is gradually supported. The developing roller 4 is pressed against the image carrier 1 until it reaches a predetermined nip width.
Next, as shown in FIG. 3, when the power is cut off, the capacitor is switched to be connected to the driving means for driving the cam by a relay or the like, and the driving means is driven by the electricity charged in the capacitor, and the position near the maximum radius. The cam is rotated by a predetermined angle from the position to the position of the minimum radius. As the cam 20 rotates, the developing device instantaneously moves in the direction away from the image carrier through the step of the cam, and the pressing force of the developing roller is relaxed or separated.
[0030]
When the developing device 2 is moved to the image carrier 1 by the operation of the cam 20 and the developing roller 4 is pressed against the image carrier 1 so as to have a predetermined nip width, the gear 15a provided on the image carrier 1 and development are performed. The gear 15b provided on the roller 4 is engaged with the gear 4 so that driving force can be transmitted. Further, when the developing device 2 is moved away from the image carrier 1 and the pressing force of the developing roller 4 is reduced or separated, the gear 15a of the image carrier 1 and the gear 15b of the developing roller 4 are completely separated from each other. In addition, the drive cannot be transmitted between the gear tips, but they are slightly engaged. Thereby, it can mesh | engage without the front-end | tips of gear 15a, 15b colliding by the press of the developing roller 4 again.
[0031]
Next, the operation will be described. First, in a state where the image carrier 1 rotates in the direction of arrow A, the residual potential remaining on the image carrier 1 is removed from the eraser lamp, and then the corona charger or charging roller. The surface of the image carrier is uniformly charged by a charger such as the above. Subsequently, digital exposure is performed by the exposure device, and an electrostatic latent image is formed on the image carrier 1. The latent image is conveyed to a position in contact with the developing roller 4 of the developing device 2 by the rotation of the image carrier 1, that is, to the developing nip section.
[0032]
On the other hand, in the developing device 2, almost simultaneously with the rotation of the image carrier 1, the developing roller 4, the supply roller 6, and the stirring member 7 are rotated in the directions indicated by the arrows by drive sources (not shown), and the developing roller 4, A predetermined bias voltage is applied to the supply roller 6 and the layer thickness regulating member 5.
[0033]
By the rotation of the stirring member 7 and the supply roller 6, the toner in the developing container 3 is stirred and supplied to form a toner layer on the developing roller 4. The toner layer is regulated by the layer thickness regulating member 5 so as to be a uniform thin layer of 1 to 3 toners, and then conveyed to the development nip section as the developing roller rotates.
[0034]
The thinned toner is supplied to the electrostatic latent image on the image carrier in the development nip section, and is developed by being attracted to adhere to form a visible toner image.
[0035]
The toner image is conveyed to a transfer area (not shown) by the rotation of the image carrier 1, and an electric field having a polarity opposite to the polarity of the toner is applied from the back side of the transfer material by the action of a transfer device such as a transfer corona or a transfer roller. Then, the toner is transferred onto the transfer material, and the transferred toner image is fixed on the transfer material by a fixing unit (not shown). On the other hand, the residual toner on the image carrier that is not transferred to the transfer material is exposed to the entire surface by the eraser so as to become substantially the same potential as the dark portion potential (image background portion potential) of the image carrier, and then the same as described above. Then, it is charged and exposed for the next image formation, and is again carried to the developing roller 4. The developing roller 4 collects the toner remaining on the image carrier 1 to the developing device 2 and provides new toner to the surface of the image carrier 1 to develop the next latent image.
[0036]
An image carrier 1 composed of an OPC photosensitive member having a diameter of 120 mm and a length of about 930 mm corresponding to the A0 size, a surface apparent hardness of 25 to 35 degrees having a diameter of 40 mm and a length of about 930 mm, and a volume resistivity of about 3 × 10 ⁶ Ω · cm Development roller 4 having a surface roughness of about 10 μm, the amount of biting of the development roller 4 into the image carrier 1 is about 0.5 to 3 mm (1/40 to 3/20 times the radius of the development roller), and the development nip The contact roller provided on the developing roller by pressing of the cam is brought into contact with the image carrier so that the width (developing nip section) is 3.5 to 10 mm, and the developing roller 4 is arranged to have a predetermined nip width. Then, the driving force of the image carrier is transmitted to the developing roller by a gear, and the developing roller 4 is rotated in the forward direction with the image carrier 1 at a speed substantially equal to the peripheral speed of the image carrier 1 at about 200 mm / sec. . As the supply roller 6, a sponge roller having a volume resistivity of 5 × 10 ⁴ Ω · cm was used. A bias of about 350 V to 550 V was applied to the supply roller 6 having a volume resistivity of 5 × 10 ⁴ Ω · cm applied to the developing roller 4, and a toner having an average particle diameter of 8 μm was applied to the developing roller 4 by the supply roller 6. Thereafter, a toner layer is formed by the layer thickness regulating member 5 so that the layer thickness on the developing roller 4 is 1 to 3 times the average particle diameter of the toner, and the electrostatic potential having a dark portion potential of about 550 V to 650 V and a light portion potential of about 20 V is formed. Development was performed by bringing the image carrier 1 into contact with the image carrier 1 on which the latent image was formed, and then transferred to a transfer material and fixed to obtain a good final image.
[0037]
In this development process, in the development nip section from the contact start point of the development roller 4 to the contact release point, the moving speed of the local portion of the development roller 4 that contacts the surface of the image carrier 1 is the image carrier at the contact start point. 1 is substantially the same as the peripheral speed of the developing roller 4, but the radius of the local portion of the developing roller in the developing nip section changes due to the elasticity of the developing roller 4 itself and the above-described biting of the developing roller 4 with respect to the image carrier 1. It is considered that the moving speed gradually becomes lower than the peripheral speed of the image carrier, and thereafter, the moving speed gradually recovers to the original speed and then moves away from the contact with the image carrier.
[0038]
The operation of the local portion of the developing roller in the developing nip section described above has a good effect on cleaning of the residual toner on the image carrier, that is, as described above with respect to the residual toner on the image carrier 1. It is considered that the blade effect for removing the toner is generated by the operation of the local portion for changing the moving speed and the unevenness of the surface of the developing roller, so that good cleaning is performed.
[0039]
Further, if the image bearing member and the developing roller as shown in the above example is a contact type, the relationship that the resistance value is too low leakage, toner, but are not limited to, a polymerized toner 10 ⁶ A high resistance or insulating material of Ω · cm or more is used, and in particular, a spherical shape having a particle size of 5 to 8 μm and a charge amount of 50 μC / g or more are preferable.
[0040]
【The invention's effect】
As described above, according to the present invention, in the non-magnetic one-component developing device that presses the developing roller against the image carrier with the contact roller so as to have a predetermined nip width, the drive of the image carrier is transmitted to the developing roller by the gear. As a result, image blurring is eliminated and a stable image can be obtained. In addition, when the developing device is not used, the developing device is moved away from the image carrier so that the gear of the image carrier and the gear of the developing roller are slightly engaged so as not to completely separate. As a result, the gears are smoothly meshed and not damaged by the pressing of the developing device again.
[Brief description of the drawings]
FIG. 1 is a schematic side view showing a preferred example of a developing device according to the present invention.
FIG. 2 is a schematic top view of a developing device according to the present invention.
FIG. 3 is a schematic side view showing a state where the developing device is moved away from the image carrier.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image carrier 2 Developing device 3 Developing container 4 Developing roller 5 Layer thickness regulating member 6 Supply roller 7 Stirring member 8 Opening 9 Toner cartridge 10 Flange 11 Center shaft 12 Intermediate layer 13 Surface layer 14a, b Bias power supply 15a, b Gear 16 Center shaft 17 Contact roller 18 Center shaft 19 Stirring blade 20 Cam 21 Switch

Claims

A thin toner layer made of a non-magnetic one-component toner is formed on the developing roller, and the electrostatic latent image formed on the surface of the image carrier is brought into contact with the surface of the image carrier so as to have a predetermined nip width. A developing device for developing an image by supplying a developer on a developing roller to the image, and the image bearing member and the developing roller are arranged so that the circumferential speed of the image bearing member and the circumferential speed of the developing roller are substantially the same. In an electrophotographic apparatus comprising an image carrier set to rotate in the forward direction and a non-magnetic one-component developing device ,
A gear provided on the flange portion of the image carrier is meshed with a gear provided on an end portion of the developing roller to transmit the drive from the image carrier to the developing device, and further provided on both ends of the developing roller. The contact roller is brought into contact with both end sides of the image carrier to regulate the nip width,
When the image carrier and the developing roller are separated from each other, the tip of the gear provided at the flange portion of the image carrier and the end of the developing roller by the pressing of the developing roller again. An image carrier and a non-magnetic one-component developing device, characterized in that the gear of the image carrier and the gear of the developing roller are slightly meshed so that they can be meshed without colliding with the tip. Electrophotographic equipment .

2. An electrophotographic apparatus comprising an image carrier and a non-magnetic one-component developing device according to claim 1, wherein a nip width at which the elastic developing roller contacts the surface of the image carrier is 4 mm or more.