JP3715535B2

JP3715535B2 - Developing device and image forming apparatus having the same

Info

Publication number: JP3715535B2
Application number: JP2001009241A
Authority: JP
Inventors: 克己足立; 将実佐久間; 太介上村; 潔戸泉
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2001-01-17
Filing date: 2001-01-17
Publication date: 2005-11-09
Anticipated expiration: 2021-01-17
Also published as: JP2002214910A

Description

【０００１】
【発明の属する技術分野】
本発明は潜像担持体（像担持体）上に形成される静電潜像を現像剤などによって現像する現像装置、およびこれを備えた画像形成装置に関し、特に、進行波電界を用いて現像剤を搬送する機構（電界カーテン）を利用するものに係わる。
【０００２】
【従来の技術】
複写機、プリンタ、ファクシミリなど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、マグネットブラシを用いた二成分方式の現像装置や、一成分現像剤をブレードなどにより現像ローラなどの現像剤担持体に押圧して薄層を形成し、像担持体である感光体と接触させて現像を行うようにしたものが知られており、すでに実用化に至っている。
【０００３】
一方、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あり、このものは、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）を利用している。
【０００４】
そして、電界カーテンを用いた現像装置としては、例えば、特開平３−２１９６７号公報に開示されるように、現像剤担持搬送体により搬送される現像剤を予備荷電する予備荷電手段と、現像剤担持搬送体上に電界カーテンを作用させる電界カーテン発生手段とを設ける。また、予備荷電手段としては、発泡ウレタンなどからなる予備荷電ローラが用いられ、この予備荷電ローラが現像剤担持搬送体に接するように設けられ、かつ、予備荷電ローラに先端が接するようにブレードが設けられている。そして、予備荷電ローラは、現像剤担持搬送体との間で現像剤を摩擦することにより、現像剤の予備帯電を行うとともに現像剤の層厚も規制する。この場合、予備荷電ローラの周辺を覆うように現像装置の筐体が配置され、現像領域への現像剤の飛散等を防ぐようにしている。
【０００５】
ところで、上記従来のものでは、現像剤担持搬送体が現像装置内で回転するため、現像装置が非常に大型化することになり、かかる点から、本発明者らは、先に出願した特願２０００−２３４４７１において、進行波電界により現像剤（トナー）を搬送する現像剤搬送手段を像担持体に対して突状に配置し、現像剤に所定の電荷を付与すると共に現像剤搬送手段に現像剤を供給する現像剤帯電手段を設け、現像に寄与しなかった現像剤を現像装置本体内に回収する回収手段、現像剤搬送手段、現像剤帯電手段および装置本体の壁面により囲まれる空間に現像剤を収容するようにしたものを提案している。このものでは、現像装置を小型化した上で、現像剤帯電手段により現像剤の帯電量を制御して現像剤搬送手段に供給する供給量を安定させることで搬送量を安定させると共に、現像に寄与しなかった現像剤を回収手段によって確実に装置内に回収することができることになる。
【０００６】
【発明が解決しようとする課題】
しかしながら、上記提案のものにおいても、以下に示すような課題を包含していることが判明した。
【０００７】
つまり、現像剤帯電手段や回収手段の近傍で飛散トナーが多く発生することが判明し、この飛散トナーが像担持体（感光体）に付着して画質が劣化するおそれがある。
【０００８】
また、現像剤帯電手段の近くに設けられた封止部材（ブレード）に現像剤が付着し、この現像剤の付着によって、封止部材の局所的な帯電が生じることがある。このような現象によって、進行波電界が封止部材の局所的な帯電により乱され、搬送される現像剤の層厚不均一を引き起こす原因となり、現像剤を円滑かつ確実に搬送することができない。
【０００９】
本発明は、かかる点に鑑みてなされたものであり、その目的とするところは、進行波電界を用いて現像剤を搬送する機構（電界カーテン）を利用する場合において、現像剤の飛散による画質劣化および局所的な帯電を防止し、現像剤を円滑かつ確実に搬送することができる現像装置およびこれを備えた画像形成装置を提供することにある。
【００１０】
【課題を解決するための手段】
上記目的を達成するために、本発明では、現像装置として、静電潜像をその表面に担持する像担持体に対向する現像領域に配置され、基材中に所定間隔を存して複数配列された電極に対して多相電圧の印加により形成される進行波電界によって現像剤を搬送する現像剤搬送手段と、この現像剤搬送手段の表面に接触もしくは近接位置で対峙するように設けられ、現像剤搬送手段に現像剤を供給する供給手段および現像剤搬送手段上から現像剤を回収する回収手段のうちの少なくとも一方と、上記現像剤搬送手段と上記供給手段または上記回収手段との接触もしくは近接位置にて発生する現像剤の飛散を防止すべく上記供給手段および回収手段のうちの少なくとも一方の周辺を覆うように配置された被覆手段とを備える。そして、上記供給手段および回収手段のうちの少なくとも一方の周辺に対応する被覆手段に、導電性を有する領域を設けている。
【００１１】
この特定事項により、供給手段および回収手段のうちの少なくとも一方の周辺において飛散する現像剤は、現像剤の供給手段近傍での現像剤の供給や、現像剤の回収手段近傍での現像剤の回収が行われる際に、これらの供給手段近傍あるいは回収手段近傍において飛散し易い状況にあるが、被覆手段により閉じこめられることになる。このため、飛散した現像剤が像担時体の不必要な箇所に付着することがなくなり、画像劣化を防止して良好な画像形成を行うことが可能となる。しかも、現像剤の飛散によって画像形成装置の機内汚れを引き起こすことも防止され、使用者の操作性やメンテナンス性を向上させることも可能となる。更に、被覆手段に導電性を有する領域が設けられているので、トナーが付着しても被覆手段での局所的な帯電を抑制する効果が得られることになり、このことから、被覆手段が絶縁性である場合に被覆手段への飛散現像剤の付着により被覆手段が局所的に著しく帯電するなどして、供給手段や回収手段からの現像剤の飛散を助長したり、現像剤搬送状態に不具合をもたらすことがなくなり、安定した現像剤の供給、搬送、回収を行うことが可能となる。
【００１２】
特に、より安定した現像剤の供給、搬送、回収を行うものとして、以下の構成が掲げられる。
【００１３】
つまり、任意の電圧を印加する電圧印加手段を被覆手段に設けている。
【００１４】
この特定事項により、被覆手段に現像剤が付着して著しく帯電した際にも、被覆手段を除電することが可能となり、安定した現像剤の供給、搬送、回収を行うことが可能となる。
【００１５】
特に、画像の品質を向上させるものとして、以下の構成が掲げられる。
【００１６】
つまり、電圧印加手段により被覆手段に印加される電圧を、被覆手段と現像剤搬送手段との間において静電潜像の現像に寄与すべく所定の極性を有する現像剤を現像剤搬送手段側へ移動させる電界が生じるような値に設定している。
【００１７】
この特定事項により、現像剤の供給手段近傍で飛散する現像剤が、被覆手段と現像剤搬送手段との間の電界により、被覆手段に付着せずに現像剤搬送手段側に戻され、静電潜像の現像に使用されるべく現像剤搬送手段により搬送されることになる。このため、被覆手段への過剰な現像剤の付着が抑制され、安定した現像剤の供給、搬送工程が良好に行われ、画像の品質を一層向上させることが可能となる。
【００１８】
また、電圧印加手段により被覆手段に印加される電圧を、被覆手段と現像剤搬送手段との間において所定の極性を有する現像剤を現像剤搬送手段側へ移動させる電界が生じるような値に設定し、かつ、被覆手段と供給手段との間において静電潜像の現像に寄与すべく上記所定の極性を有する現像剤とは逆極性を有する現像剤を供給手段側へ移動させる電界が生じるような値に設定している場合には、供給手段近傍で飛散する現像剤が、被覆手段と現像剤搬送手段との間の電界により、被覆手段に付着せずに現像剤搬送手段側に戻され、静電潜像の現像に使用されるべく現像剤搬送手段により搬送される。一方、供給手段近傍で飛散している現像剤の中には、所望の極性（所定の極性）とは逆極性の現像剤（静電潜像の現像に寄与しない現像剤）が微量含まれているが、これら逆極性現像剤は供給手段側へ移動し、よって被覆手段への過剰な現像剤付着が抑制され、安定した現像剤の供給、搬送工程が良好に行われ、画像の品質をさらに向上させることが可能となる。
【００１９】
そして、電圧印加手段により被覆手段に印加される電圧に交流電圧を重畳している場合には、被覆手段の除電が効果的に行われ、飛散した現像剤が被覆手段に付着し難くいものとなり、これによって安定した現像剤の供給、搬送工程が良好に行われ、画像の品質をより一層向上させることが可能となる。
【００２０】
しかも、電圧印加手段により被覆手段に印加される交流電圧の周波数を、現像剤搬送手段に印加される電圧の周波数よりも低く設定している場合には、飛散している現像剤を移動させるために必要な電界形成時間を長くとることが可能となり、安定した現像剤の供給、搬送工程がより良好に行われ、画像の品質をより効果的に向上させることが可能となる。
【００２１】
特に、被覆手段に対し振動を付与する振動付与手段を被覆手段に備えている場合には、被覆手段に振動を付与することで、被覆手段への現像剤付着量の蓄積が軽減され、これにより安定した現像剤の供給、搬送、回収工程が良好に行われ、画像の品質をより一層効果的に向上させることが可能となる。
【００２２】
また、被覆手段の振動の振幅Ａ（ｍ）および周波数ｆ（Ｈｚ）を、
Ａ×ｆ²＞１０³
の関係を満たすように設定している場合には、振動付与による現像剤の除去が効果的に行われ、これにより安定した現像剤の供給、搬送、回収工程が良好に行われて、画像の品質をより一層向上させることが可能となる。
【００２３】
特に、飛散している現像剤を効果的に封じ込めるものとして、以下の構成が掲げられる。
【００２４】
つまり、現像剤搬送手段の表面に対し接触もしくは近接位置で対峙する供給手段の周面および回収手段の周面のうちの少なくとも一方の接線方向に延びる線分と平行な供給手段および回収手段の略中心を通る線よりも現像剤搬送手段と向き合う方向に延びて該現像剤搬送手段を覆うように被覆手段を構成し、その現像剤搬送手段と向き合う方向に延びる被覆手段と現像剤搬送手段との間隙を０．０５ｍｍ以上に設定している。
【００２５】
この特定事項により、現像剤搬送手段上の現像剤の流れを妨げることなく、飛散している現像剤を効果的に封じ込めることが可能となる。
【００２６】
さらに、上述した現像装置を画像形成装置に備えている場合には、画像劣化を防止して良好な画像形成を行え、使用者の操作性やメンテナンス性が高く、かつ安定した現像剤の供給、搬送、回収を行い得る画像形成装置を提供することが可能となる。
【００２７】
【発明の実施の形態】
以下、本発明の実施の形態を図面に基づいて説明する。
【００２８】
＜第１の実施の形態＞
図１は本発明の第１の実施形態に係わる現像装置を備えた画像形成装置を示し、この画像形成装置Ｘの内部には、像担持体としての円筒状の感光体ドラム１が設けられている。この感光体ドラム１を中心として、その周囲に、帯電部材２、露光部材３、現像装置４、転写部材５、クリーニング部材６、および除電部材７が順に配置されている。また、感光体ドラム１と転写部材５との間には、記録媒体としての用紙Ｐが搬送される用紙搬送路が設けられている。この用紙搬送路の搬送方向から見て感光体ドラムの下流側には、上下一対の定着ローラ８１，８１を備えた定着装置８が配置されている。
【００２９】
電子写真プロセスでは、感光体ドラム１に原稿像、あるいはホストコンピュータ（図示せず）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によって可視化され、用紙Ｐ上に転写されて画像形成が行われる。
【００３０】
感光体ドラム１は、基材１１上に光導電層１２が形成されており、帯電部材２から上記各部材３〜７の配置順に従って回転可能となっている。まず、感光体ドラム１の表面（光導電層１２）は、帯電部材２によって所定の電位となるまで帯電される。所定電位まで帯電された感光体ドラム１の表面は、感光体ドラム１の回転によって露光部材３の位置まで到達する。この露光部材３は書き込み手段であり、画像情報に基づいて、たとえばレーザーなどの光によって帯電している感光体ドラム１の表面上に画像を書き込む。これによって、感光体ドラム１上に静電潜像が形成される。静電潜像が形成された感光体ドラム１の表面は、この感光体ドラム１の回転によって現像装置４の位置まで到達する。
【００３１】
現像装置４では、トナー搬送部材４１（現像剤搬送手段）上を搬送されるトナーによって、感光体ドラム１の表面の静電潜像をトナー像として現像する。トナー像が担持された感光体ドラム１の表面は、この感光体ドラム１の回転によって転写部材５の位置まで到達する。
【００３２】
転写部材５は、感光体ドラム１の表面上のトナー像を、用紙Ｐ上に転写する。感光体ドラム１から用紙Ｐ上に転写されたトナー像は、定着装置８によって用紙Ｐ上に定着される。
【００３３】
トナー像が転写された後の感光体ドラム１の表面は、この感光体ドラム１の回転によってクリーニング部材６の位置まで到達する。クリーニング部材６は、感光体ドラム１の表面に残留しているトナーや紙粉などを除去する。クリーニング部材６によってクリーニングされた感光体ドラム１の表面は、この感光体ドラム１の回転によって除電部材７の位置まで到達する。除電部材７は、感光体ドラム１の表面に残留している電位を除去する。上述した一連の動作によって一回の画像形成が終了する。
【００３４】
上記感光体ドラム１としては、たとえば、アルミニウムなどの金属ドラムを基材１１として、その外周面にアモルファスシリコン（ａ−Ｓｉ）、セレン（Ｓｅ）や有機光半導体（ＯＰＣ）などの光導電層１２が薄膜状に形成されてなる構成が挙げられるが、特に限定されるものではない。
【００３５】
上記帯電部材２としては、たとえばタングステンワイヤなどの帯電線・金属製のシールド板、グリッド板などよりなるコロナ帯電器や帯電ローラ、帯電ブラシなどの構成が挙げられるが、特に限定されるものではない。
【００３６】
上記露光部材３としては、たとえば半導体レーザや発光ダイオードなどが挙げられるが、特に限定されるものではない。
【００３７】
上記転写部材５としては、たとえば、コロナ転写器、転写ローラ、転写ブラシなどが挙げられるが、特に限定されるものではない。
【００３８】
上記クリーニング部材６としては、クリーニングブレードなどが挙げられるが、特に限定されるものではない。
【００３９】
上記除電部材７としては、除電ランプなどが挙げられるが、特に限定されるものではない。
【００４０】
本実施形態では、トナー搬送部材４１と感光体ドラム１との間には一定の間隔が設けられ、感光体ドラム１の表面の静電潜像を非接触で現像する構成となっているが、本発明はこれに限定されるものではなく、トナー搬送部材と感光体ドラムの表面とを接触させて接触現像を行う構成であっても構わない。
【００４１】
上記現像装置４は、図２に示すように、ケーシング４０と、トナー搬送部材４１と、ミキシングパドル４２と備えている。ケーシング４０はトナーを内部に収容するものである。ミキシングパドル４２は、ケーシング４０内に収容されているトナーを混合するためのものである。
【００４２】
上記トナー搬送部材４１は、感光体ドラム１の現像領域Ａに対向して略平面を形成するようなベルト形状となっている。なお、本実施形態では、トナー搬送部材４１としてベルト形状のものを示しているが、トナー搬送部材４１の形状はこれに限定されるものではなく、例えば、半円弧状のものでも構わない。
【００４３】
また、トナー搬送部材４１は、現像装置４における上下方向に対して若干傾斜して、感光体ドラム１の表面における現像領域Ａの接線に対して略平行となるように配置されている。また、ベルト形状のトナー搬送部材４１が上記配置を保持できるように、トナーを搬送する表面とは反対側の面に、トナー搬送部材４１を保持する支持部材４３が設けられている。
【００４４】
トナー搬送部材４１の下方側端部には、このトナー搬送部材４１の表面上を搬送されるトナーを供給する供給部材４４（供給手段）が設けられている。一方、トナー搬送部材の上方側端部には、このトナー搬送部材４１の表面のトナーを回収する回収部材４５（回収手段）が設けられている。さらに、これら供給部材４４および回収部材４５の周囲を覆う被覆部材４６（被覆手段）が設けられ、この被覆部材４６によって、現像剤の感光体ドラム１側への飛散を防止するようにしている。被覆部材４６は、ケーシング４０と一体的に設けられた基体４６ａと、この基体４６ａの内側に取り付けられた導電性を有する層状の導電部４６ｂ（導電領域）とを備えている。この場合、被覆部材４６の基体４６ａとしては、絶縁性の樹脂やフィルム状のものが適用される一方、導電部４６ｂとしては、基体４６ａにアルミニウムや金等の金属膜を蒸着等の手段により形成したものでも良いし、基体４６ａそのものに導電性粒子を含ませた導電性樹脂や導電性フィルムであっても良いし、あるいは被覆部材４６が金属板であってもよく、導電性を示すものであれば特に限定されるものではない。
【００４５】
また、トナー搬送部材４１には、多相交流電源４７と現像バイアス電源４８とが直列に接続されている。上記供給部材４４および回収部材４５は、いずれも円筒形状を呈し、ベルト形状のトナー搬送部材４１の表面に対し回転可能に接触している。
【００４６】
上記供給部材４４は、ケーシング４０内に収容されているトナーをトナー搬送部材４１に供給するためのものであり、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もよい（電圧印加も可能）。上記供給部材４４とトナー搬送部材４１との接触圧力や供給部材４４に印加する電圧値を適切な値に設定し、供給部材４４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、上記供給部材４４の前段に、例えば薄板状のブレード（材料としては、上記供給部材４４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。
【００４７】
上記回収部材４５は、感光体ドラム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４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、たとえば上記供給部材４４と同様のものを使用することができる。
【００４８】
上記支持部材４３は、ベルト形状のトナー搬送部材４１を感光体ドラム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。
【００４９】
上記トナー搬送部材４１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、絶縁層よりなる基材４１ａ上に、電界カーテン作用を発生させる進行波発生電極４１ｂ，…が、４本を一組として複数組が順次連続して配設されている。このトナー搬送部材４１の表面側は表面保護層４１ｃによって覆われている。そして、これらの電極４１ｂ，…にトナー搬送のための多相交流電源４７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４１の表面においてそれと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Ａ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。
【００５０】
上記トナー搬送部材４１の具体例を挙げると、たとえば、基材４１ａ：ポリイミド（厚さ２５μｍ）、進行波発生電極４１ｂ：銅（厚さ１８μｍ）、表面保護層４１ｃ：ポリイミド（厚さ２５μｍ）といった構成を挙げることができる。また、上記進行波発生電極４１ｂは、幅４０μｍの微小電極となっているが、これが１００ｄｐｉ（ｄｏｔｐｅｒｉｎｃｈ）〜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。なお、本実施の形態では、４本の進行波発生電極４１ｂ，…を１組とし、これら各組の進行波発生電極４１ｂ，…に対して、たとえば図４に示すような電圧波形の４相の交番電圧を印加し、進行波発生電極４１ｂ，…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本の進行波発生電極を１組として３相の交番電圧を印加しても構わない。また、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〜１０ｋＨｚが好ましく用いられるが、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。
【００５１】
ここで、供給部材４４あるいは回収部材４５付近でのトナー飛散の原因について述べる。
【００５２】
供給部材４４あるいは回収部材４５は、数１０ｍｍ／ｓないし１００〜２００ｍｍ／ｓ程度の回転周速度で回転する。
【００５３】
一方、トナー搬送部材４１上を進行波電界により移動するトナー速度は非常に早く、トナーの特性（比電荷や粒径等）や、トナー搬送部材４１への印加電圧の条件（周波数やピーク間電圧等）や、トナー搬送部材４１の構成条件（電極間ピッチ、表面保護層４１ｃの厚み等）により変動を受けるが、数１０ｍｍ／ｓないし数１０００ｍｍ／ｓの速度で移動する。
【００５４】
よって、供給部材４４あるいは回収部材４５と、トナー搬送部材４１の最近接点近傍では、移動速度差の大きいトナー層が存在するため、トナー同士の衝突等により、飛散が発生しやすいと考えられる。供給部材４４や回収部材４５が存在しないトナー搬送部材領域（例えば現像領域Ａ近傍）では、トナー移動速度が大きく異なる状態が発生しないため、トナー飛散が起こりにくいものとなる。
【００５５】
したがって、本実施形態では、供給手段４４および回収手段４５の周辺において飛散するトナーは、供給手段４４近傍でのトナーの供給や、回収手段４５近傍でのトナーの回収が行われる際に、これらの供給手段４４近傍および回収手段４５近傍において飛散し易い状況にあるが、被覆部材４６によりケーシング４０内に閉じこめられることになる。このため、飛散したトナーが感光体ドラム１の不必要な箇所に付着することがなくなり、画像劣化を防止して良好な画像形成を行うことができる。
【００５６】
しかも、トナーの飛散によって画像形成装置Ｘの機内汚れを引き起こすことも防止され、使用者の操作性やメンテナンス性を向上させることもできる。
【００５７】
更に、被覆部材４６の基体４６ａの内側に導電部４６ｂが設けられているので、トナーが付着しても被覆部材４６での局所的な帯電を抑制する効果が得られる。このことから、被覆部材が絶縁性である場合に飛散したトナーが被覆部材に付着して被覆部材が局所的に著しく帯電するなどし、供給手段４４や回収手段４５からのトナーの飛散を助長したり、トナー搬送状態に不具合をもたらすことがなくなり、安定したトナーの供給、搬送、回収を行うことができる。
【００５８】
さらに、上述した現像装置４を画像形成装置Ｘに備えることで、画像劣化を防止して良好な画像形成を行え、使用者の操作性やメンテナンス性が高く、かつ安定した現像剤の供給、搬送、回収を行い得る画像形成装置を提供することができる。
【００５９】
＜第１の変形例＞
なお、本実施形態では、被覆部材４６の基体４６ａの内側に導電部４６ｂを設けるのみとしたが、図２に仮想線（二点鎖線）で示すように、供給部材４４および回収部材４５の周囲をそれぞれ覆う被覆部材４６の導電部４６ｂに対し任意の電圧を印加する電圧印加手段としての第１電源４６ｃおよび第２電源４６ｄが設けられていても良い。この場合、トナーの付着により被覆部材４６が帯電し、この帯電電荷が蓄積していった際に、帯電電荷を除電することが可能となり、これによって、被覆部材４６の帯電が効果的に抑制され、安定したトナーの供給、搬送、回収を行うことができる。
【００６０】
＜第２の変形例＞
また、第１電源４６ｃおよび第２電源４６ｄ（電圧印加手段）により被覆部材４６の導電部４６ｂに与える印加電圧として、被覆部材４６とトナー搬送部材４１との間において、所望の極性を有するトナーをトナー搬送部材４１側へ移動させる電界が生じるような値に設定しても良い。この場合、供給部材４４および回収部材４５近傍で飛散するトナーが、被覆部材４６とトナー搬送部材４１との間の電界により、被覆部材４６に付着せずにトナー搬送部材４１側に戻され、静電潜像の現像に使用されるべくトナー搬送部材４１により搬送されて行く。よって被覆部材４６への過剰なトナーの付着が抑制され、これによって安定したトナーの供給、搬送、回収工程が良好に行われ、画像の品質をより一層向上させることができる。
【００６１】
具体的には、負極性トナーを使用する場合には、図５に示すような電圧設定を行う。トナー搬送部材４１に０〜−４００Ｖの交流電圧を印加し、供給部材４４に−５００Ｖの電圧を印加する。このとき、供給部材４４側の被覆部材４６に−６００Ｖの電圧を印加する。このような設定にした場合、被覆部材４６とトナー搬送部材４１との間には負極性トナーをトナー搬送部材４１側に移動させるような電界が生じるため、飛散したトナーが再びトナー搬送部材４１側に戻され、被覆部材４６側へのトナー付着を抑制することができる。
【００６２】
一方、回収部材４５側の被覆部材４６についても同様な構成をとることができる。たとえば、図５に示すようにトナー搬送部材４１に０〜−４００Ｖの電圧を印加し、回収部材４５に＋１００Ｖの電圧を印加する。このとき、回収部材４５側の被覆部材４６に−６００Ｖの電圧を印加する。このような設定にした場合にも、被覆部材４６とトナー搬送部材４１との間には負極性トナーをトナー搬送部材４１側に移動させるような電界が生じるため、上述のような効果が得られる。
【００６３】
＜第３の変形例＞
そして、供給部材４４を覆う被覆部材４６に印加する電圧として、被覆部材４６とトナー搬送部材４１との間において感光体ドラム１上の静電潜像の現像に寄与すべく所定の極性を有するトナーをトナー搬送部材４１側へ移動させる電界が生じるような値に設定され、かつ被覆部材４６と供給部材４４との間において上記所定の極性を有するトナーとは逆極性を有するトナーを供給部材４４側へ移動させる電界が生じるような値に設定しても良い。
【００６４】
具体的には、図６に示すような電圧設定が挙げられる。つまり、トナー搬送部材４１に０〜−４００Ｖの交流電圧を印加し、供給部材４４に−５００Ｖの電圧を印加する。このとき、供給部材４４側の被覆部材４６に−４００Ｖの電圧を印加する。このような設定にした場合、被覆部材４６とトナー搬送部材４１との間には負極性トナーをトナー搬送部材４１側に移動させるような電界が生じ、また、被覆部材４６と供給部材４４との間には逆極性トナーを供給部材４４側に移動させるような電界が生じる。
【００６５】
この場合、供給部材４４近傍で飛散するトナーが、被覆部材４６とトナー搬送部材４１との間の電界により、被覆部材４６に付着せずにトナー搬送部材４１側に戻され、静電潜像の現像に使用されるべくトナー搬送部材４１により搬送されて行く。また、基本的には供給部材４４からトナー搬送部材４１へ移動するトナーは所望の極性のものだけが移動し、逆極性のトナーについてはトナー搬送部材４１へ移動せずに再び現像装置４のケーシング４０内に戻されるが、微量に逆極性のトナーも移動してしまうことがある。このとき、供給部材４４近傍で飛散しているトナーの中には、所望の極性と逆極性のものが微量含まれているが、これら逆極性のトナーは供給部材４４側へ移動する。よって被覆部材４６への過剰なトナーの付着を抑制することができる。また、この効果により、トナー搬送部材４１上を移動するトナー（現像工程に供されるトナー）中の逆極性トナーの量を低減する効果もある。即ち、供給部材４４にて逆極性トナーをトナー搬送部材４１側に移動させず、積極的に供給部材４４側に戻し、これをケーシング４０内に戻す効率を向上させることができる。よって、トナー搬送部材４１上を移動し、現像工程にて使用されるトナー中の逆極性トナーの比率が低減され、逆極性トナーのよる感光体ドラム１の地かぶり（本来、非画像部である領域へのトナー付着による感光体ドラム１のトナー汚れであり、逆極性トナーが主たる原因となることが多い。）も低減でき、より安定したトナーの供給、搬送、現像、回収工程が良好に行われ、画像の品質をより一層向上させることができる。
【００６６】
＜第４の変形例＞
更には、第１電源４６ｃおよび第２電源４６ｄ（電圧印加手段）により被覆部材に印加される電圧に、交流電圧を重畳しても良い。
【００６７】
具体的には、図７に示すような電圧設定が挙げられる。つまり、トナー搬送部材４１に０〜−４００Ｖの電圧を印加し、供給部材４４に−５００Ｖの電圧を印加する。このとき、供給部材４４側の被覆部材４６（導電部４６ｂ）に−３００Ｖの直流電圧にピーク間電圧６００Ｖの交流電圧を重畳する。即ち、被覆部材４６には０Ｖから−６００Ｖの電圧が印加される。例えば供給部材４４に−６００Ｖの電圧が印加されたときは、負極性トナーをトナー搬送部材４１側に戻すための電界が十分形成され、また０Ｖが印加されたときには、逆極性トナーを供給部材４４側に戻すための電界が十分形成され、上述の第３の変形例の作用をより効果的に実現できる。
【００６８】
この理由について更に詳細に説明する。
【００６９】
供給部材４４に印加する電圧をあまり大きくしすぎると、供給部材４４からトナー搬送部材４１への電界によるトナーの押し付け力が強くなり、トナー搬送部材４１上の進行波電界でトナーを移動させることが困難になる場合がある。逆に、供給部材４４への印加電圧が小さすぎると、供給部材４４からトナー搬送部材４１へ十分なトナー供給が行えず、必要なトナー搬送量を得ることができなくなる場合がある。よって、供給部材４４に印加する電圧は適正値が存在する。即ち、被覆部材４６に印加する電圧を直流電圧のみとした場合、被覆部材４６に印加できる電圧範囲は、トナー搬送部材４１に印加される電圧と供給部材４４に印加される電圧の間の値とする必要がある。このため、供給部材４４とトナー搬送部材４１との電位差が小さい場合、飛散トナーをトナー搬送部材４１や供給部材４４に戻すための電界強度を十分確保できないことがある。しかしながら、本変形例の構成によれば、所望の極性トナーをトナー搬送部材４１に戻す電界と、逆極性トナーを供給部材４４に戻す電界を大きくとることができ、飛散トナーの付着を有効に抑制できる。
【００７０】
また、被覆部材４６へのトナー付着による帯電が生じた際にも、交流電圧を重畳することで、被覆部材４６の除電効果が向上し、好適である。本効果は回収部材４５にも適用可能である。
【００７１】
さらに、被覆部材４６に印加する電圧の周波数は、トナー搬送部材４１に印加する電圧の周波数より低くする方が望ましい。例えば、トナー搬送部材４１への印加電圧周波数の１／２以下とすることが望ましい。このような条件とすることで、飛散トナーを移動させるための電界形成時間が長くとれる。またトナー搬送部材４１の電圧の位相との兼ね合いによっては、被覆部材４６とトナー搬送部材４１との間の電位差が最小となる状態が起こる可能性があり、飛散トナーを所望の場所へ移動させるための電界が弱まる危険性がある。しかし、本変形例の構成によれば、上記課題も回避でき、より好適である。
【００７２】
要するに、本変形例の構成によれば、交流電圧を重畳することで、被覆部材４６への付着トナー蓄積が押えられ、かつトナー付着による帯電を効果的に除電でき、より安定したトナーの供給、搬送、回収工程が良好に行われ、画像の品質をより一層向上させることができる。
【００７３】
＜第２の実施の形態＞
次に、本発明の第２の実施形態を図８に基づいて説明する。
【００７４】
この実施形態では、被覆部材に振動を付与する手段を設けている。なお、被覆部材を除くその他の構成は第１の実施形態の場合と同じであり、同一の部分については同一の符号を付してその説明を省略する。
【００７５】
すなわち、本実施形態では、図８に示すように、被覆部材９は約１００μｍのＰＥＴ（ポリエチレンテレフタレート）フィルムよりなり、この被覆部材９に振動を付与する振動付与手段９１を設けている。この振動付与手段９１としては、例えば積層型のピエゾ素子等を用いることができる。このピエゾ素子の一方の端をケーシング４０に固定し、他端を被覆部材９側に固定する。
【００７６】
これにより、飛散したトナーが被覆部材９に付着しても、被覆部材９の振動によってふるい落とされ、被覆部材９への付着トナーの蓄積を防ぐことができる。このような作用により、被覆部材９へのトナー蓄積による被覆部材９の帯電が抑制され、安定したトナーの供給、搬送、回収工程を行うことができ、良好な画像形成を得ることができる。
【００７７】
＜変形例＞
なお、本実施形態では、被覆部材９に単に振動を付与するに止めたが、振動を付与する条件として、被覆部材９の振動の振幅Ａ（ｍ）および周波数ｆ（Ｈｚ）を、
Ａ×ｆ²＞１０³
の関係を満たすように設定すると、なお好適である。
【００７８】
つまり、被覆部材９の最大振幅をＡ（ｍ）、周波数をｆ（Ｈｚ）とし、正弦波形の振動を行っているとすると、被覆部材９の時間ｔ（ｓ）に対する変位量ｘ（ｍ）は次式で表される。
【００７９】
ｘ＝Ａ×ｓｉｎ（２×π×ｆ×ｔ）
よって被覆部材９の加速度ａは、
ａ＝−４×π²×ｆ²×Ａ×ｓｉｎ（２×π×ｆ×ｔ）
となる。
【００８０】
被覆部材９に付着したトナーを除去するには、被覆部材９に付着したトナーの付着力に打ち勝つ力（ｍ×ａ。ここでｍはトナー質量、ａは被覆部材９の加速度である。）を作用させなければならない。即ち、上記の加速度ａを決める被覆部材９の振幅Ａおよび周波数ｆで決まるＡ×ｆ²値を大きくすることで、被覆部材９に付着したトナーに対する除去能力が向上する。
【００８１】
そこで、ピエゾ素子に与える電圧および周波数を変化させて上記のＡ×ｆ²値を変化させ、被覆部材９へのトナー付着による画像形成への影響を検討すると、表１に示すような結果が得られた。
【００８２】
【表１】

この表１において、Ａ×ｆ²値が１０００以上では、被覆部材９の振動による付着トナーの除去が効率的に行われ、トナー付着による被覆部材９の帯電や、付着トナーの蓄積によるトナー搬送、現像工程への影響を抑制できる。
【００８３】
これにより、安定した現像剤の供給、搬送、回収工程が良好に行われ、画像の品質をより一層向上させることができる。
【００８４】
＜他の変形例＞
また、上記第２の実施形態では、被覆部材９に導電性を与え、任意の電圧印加等を行っていない例を示したが、これに限定されるものではない。上記第１の実施形態において記載した手段を併用すれば、より良好な画像形成を行うことが可能である。
【００８５】
＜第３の実施の形態＞
次に、本発明の第３の実施形態を図９に基づいて説明する。
【００８６】
この実施形態では、被覆部材のトナー搬送部材に対する配置状態を規定している。なお、被覆部材を除くその他の構成は第１の実施形態の場合と同じであり、同一の部分については同一の符号を付してその説明を省略する。
【００８７】
すなわち、本実施形態では、図９に示すように、被覆部材１０は、トナー搬送部材４１の表面に対し接触する供給部材４４の周面および回収部材４５の周面の接線Ｓ（接線方向に延びる線分）と平行な供給部材４４および回収部材４５の略中心を通る平行線Ｈよりもトナー搬送部材４１と向き合う方向（図９では上方）に延びて該トナー搬送部材４１が覆われるように形成され、そのトナー搬送部材４１と向き合う方向に延びる被覆部材１０とトナー搬送部材４１との間隙Ｋは０．０５ｍｍ以上に設定されている。
【００８８】
この場合、被覆部材１０とトナー搬送部材４１との間隙Ｋを小さくする方が、飛散トナーの外部（被覆部材１０外部）への漏れを防ぐ点では有効である。しかし、本発明のようにトナーを進行波電界によりクラウド状にして搬送する方式では、一般的な１成分方式の現像方法（ゴムローラー、もしくは金属ローラ等のトナー担持体上に薄層トナーを形成）に比べ、トナー層の厚みが大きい。よって、あまり被覆部材１０とトナー搬送部材４１との間隙Ｋを小さくしすぎると、トナー搬送の障害となる。
【００８９】
そこで、トナー特性や進行電界形成条件を種々設定し、トナー搬送を妨げない間隙Ｋを検討した結果、５０μｍ以上の間隙Ｋとすることで良好なトナー搬送ができることが分かった。
【００９０】
また、被覆部材１０とトナー搬送部材４１との間隙Ｋを広げる方向については、被覆部材１０により覆われる供給部材４４および回収部材４５において、この供給部材４４および回収部材４５の周面がトナー搬送部材４１に向き合う位置まで被覆部材１０が供給部材４４および回収部材４５を覆う、具体的には、たとえば供給部材４４のトナー搬送部材４１に対する接線Ｓと平行な供給部材４４の略中心を通る平行線Ｈよりもトナー搬送部材４１側（図９では上側）を覆うようにすれば良い。
【００９１】
この理由としては、供給部材４４および回収部材４５がローラー状である場合を例に、図９をもとに説明する。
【００９２】
トナー搬送部材４１と最近接する位置からその直径の略半分の位置（供給部材４４の中心を通る平行線Ｈと交差する位置）までは、トナー搬送部材４１に対してトナーの供給部材４４および回収部材４５はトナー搬送部材４１と向き合う形となっている。よって、この領域では、供給部材４４および回収部材４５とトナー搬送部材４１との間には飛散現像剤を浮遊させず、いずれかの部材４４，４５の方に引き寄せるための電界が形成されている。つまり、被覆部材１０による飛散トナー隠蔽効果だけでなく、供給部材４４および回収部材４５自身が、飛散トナーを制御しようとする働きがある。しかし、供給部材４４および回収部材４５の直径の略半分の位置より下方に離れたところ、すなわちトナー搬送部材４１と向き合っていない領域では、トナー搬送部材４１との間の電界による作用で飛散したトナーを制御する機能が無くなり、被覆部材１０による隠蔽効果しか期待できなくなり、十分な飛散トナーの隠蔽効果が得られない場合がある。よって、飛散トナーを隠蔽するために被覆部材１０とトナー搬送部材４１との間隙Ｋの上限としては、供給部材４４および回収部材４５の周面がトナー搬送部材４１に向き合う位置となるように設定するのが望ましい。
【００９３】
上記構成によれば、トナー搬送部材４１上のトナーの流れを妨げることがなく、かつ飛散したトナーを効果的に封じ込めることができる。
【００９４】
【発明の効果】
以上のように、現像剤搬送手段と供給手段または回収手段との接触もしくは近接位置にて発生する現像剤の飛散を防止すべく供給手段および回収手段のうちの少なくとも一方の周辺を覆う被覆手段に、導電性を有する領域を設けることで、その周辺において飛散する現像剤を被覆手段により閉じ込めて像担時体の不必要な箇所に付着することを防止し、画像劣化を防止して良好な画像形成を行うことができるとともに、現像剤の飛散による画像形成装置の機内汚れを防止して使用者の操作性やメンテナンス性を向上させることもできる。更に、被覆手段に導電性を有する領域を設けることで、トナー付着による被覆手段での局所的な帯電の抑制効果が得られ、安定した現像剤の供給、搬送、回収を行うことができる。
【００９５】
特に、任意の電圧を印加する電圧印加手段を被覆手段に設けることで、被覆手段への現像剤の付着により著しく帯電した際に被覆手段を除電することができ、安定した現像剤の供給、搬送、回収を行うことができる。
【００９６】
特に、被覆手段への印加電圧を、被覆手段と現像剤搬送手段との間で静電潜像の現像に寄与すべく所定の極性を有する現像剤を現像剤搬送手段側へ移動させる電界が生じるような値に設定することで、供給手段近傍で飛散する現像剤を被覆手段に付着させずに現像剤搬送手段側に戻し、被覆手段への過剰な現像剤の付着を抑制し、安定した現像剤の供給、搬送工程を良好に行って、画像の品質を一層向上させることができる。
【００９７】
また、被覆手段への印加電圧を、被覆手段と現像剤搬送手段との間で静電潜像の現像に寄与すべく所定の極性を有する現像剤を現像剤搬送手段側へ移動させる電界が生じるような値に設定し、かつ被覆手段と供給手段との間で上記所定の現像剤とは逆極性を有する現像剤を供給手段側へ移動させる電界が生じるような値に設定することで、供給手段近傍で飛散する現像剤を、被覆手段に付着させずに現像剤搬送手段側に戻して搬送する一方、供給手段近傍で飛散する逆極性の現像剤を、供給手段側へ移動させて被覆手段への過剰な現像剤付着を抑制し、安定した現像剤の供給、搬送工程を良好に行って画像の品質をさらに向上させることができる。
【００９８】
そして、被覆手段への印加電圧に交流電圧を重畳することで、被覆手段の除電を効果的に行って被覆手段に飛散現像剤を付着し難くし、安定した現像剤の供給、搬送工程を良好に行って画像の品質をより一層向上させることができる。
【００９９】
しかも、被覆手段に印加する交流電圧の周波数を、現像剤搬送手段への印加電圧の周波数よりも低く設定することで、電界形成時間を長くとることができ、安定した現像剤の供給、搬送工程をより良好に行って画像の品質をより効果的に向上させることができる。
【０１００】
特に、振動付与手段を被覆手段に設けることで、被覆手段への現像剤付着量の蓄積を軽減し、安定した現像剤の供給、搬送、回収工程を良好に行って画像の品質をより一層効果的に向上させることができる。
【０１０１】
また、被覆手段の振動の振幅Ａ（ｍ）および周波数ｆ（Ｈｚ）を、
Ａ×ｆ²＞１０³
の関係を満たすように設定することで、振動付与による現像剤の除去を効果的に行え、安定した現像剤の供給、搬送、回収工程を良好に行って画像の品質をより一層向上させることができる。
【０１０２】
特に、現像剤搬送手段の表面に対し接触もしくは近接位置で対峙する供給手段の周面および回収手段の周面のうちの少なくとも一方の接線方向に延びる線分と平行な供給手段および回収手段の略中心を通る線よりも現像剤搬送手段と向き合う方向に延びて該現像剤搬送手段を覆う被覆手段と、現像剤搬送手段との間隙を０．０５ｍｍ以上に設定することで、現像剤搬送手段上の現像剤の流れを妨げることなく、飛散現像剤を効果的に封じ込めることができる。
【０１０３】
さらに、上述した現像装置を画像形成装置に備えることで、画像劣化を防止して良好な画像形成を行え、使用者の操作性やメンテナンス性が高く、かつ安定した現像剤の供給、搬送、回収を行い得る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】本発明の第１の実施形態に係わる現像装置が適用される電子写真方式を用いた画像形成装置の概略構成を示す模式図である。
【図２】同じく現像装置の構成を示す模式図である。
【図３】同じくトナー搬送部材の構成を示す模式図である。
【図４】同じくトナー搬送部材に印加される電圧波形を示す波形図である。
【図５】第１の実施形態の第２変形例に係わる現像装置への印加電圧条件の説明図である。
【図６】第１の実施形態の第３変形例に係わる現像装置への印加電圧条件の説明図である。
【図７】第１の実施形態の第４変形例に係わる現像装置への印加電圧条件の説明図である。
【図８】本発明の第２の実施形態に係わる現像装置の概略構成を示す模式図である。
【図９】本発明の第３の実施形態に係わる現像装置の概略構成を示す模式図である。
【符号の説明】
１感光体ドラム（像担持体）
４現像装置
４１トナー搬送部材（現像剤搬送手段）
４１ａ基材
４１ｂ進行波発生電極（電極）
４４供給部材（供給手段）
４５回収部材（回収手段）
４６，９，１０被覆部材（被覆手段）
４６ｂ導電部（導電性を有する領域）
４６ｃ第１電源（電圧印加手段）
４６ｄ第２電源（電圧印加手段）
９１振動付与手段
Ａ現像領域
Ｋ間隙
Ｔトナー（現像剤）
Ｘ画像形成装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developing device that develops an electrostatic latent image formed on a latent image carrier (image carrier) with a developer and the like, and an image forming apparatus including the same, and particularly, development using a traveling wave electric field. The present invention relates to an apparatus that uses a mechanism (electric field curtain) for conveying the agent.
[0002]
[Prior art]
As a developing device applied to an image forming apparatus using an electrophotographic process such as a copying machine, a printer, a facsimile, etc., a two-component developing device using a magnet brush, a developing roller using a one-component developer with a blade, etc. It is known that the developer carrying member is pressed to form a thin layer and brought into contact with a photosensitive member as an image bearing member for development, and has already been put into practical use.
[0003]
On the other hand, there is a non-contact type developing device that performs development without bringing a developer carrier into contact with an image carrier, which uses a powder cloud method, a jumping method, or an electric field curtain (traveling wave electric field). .
[0004]
As a developing device using an electric field curtain, for example, as disclosed in JP-A-3-21967, a preliminary charging unit that precharges a developer conveyed by a developer carrying carrier, and a developer Electric field curtain generating means for causing the electric field curtain to act on the carrying carrier is provided. Further, as the preliminary charging means, a preliminary charging roller made of urethane foam or the like is used. The preliminary charging roller is provided so as to be in contact with the developer carrying member, and a blade is provided so that the tip is in contact with the preliminary charging roller. Is provided. The preliminary charging roller rubs the developer with the developer carrying member, thereby precharging the developer and regulating the developer layer thickness. In this case, the housing of the developing device is disposed so as to cover the periphery of the preliminary charging roller, so that the developer is prevented from scattering to the developing region.
[0005]
By the way, in the above-mentioned conventional one, since the developer carrying member rotates in the developing device, the developing device becomes very large. From this point, the present inventors have applied for a patent application previously filed. In 2000-234471, a developer conveying means that conveys developer (toner) by a traveling wave electric field is disposed in a projecting manner with respect to the image carrier to give a predetermined charge to the developer and develop the developer on the developer conveying means. The developer charging means for supplying the developer is provided, and the developer that has not contributed to the development is collected in the developing device main body, the developer conveying means, the developer charging means and the space surrounded by the wall surface of the apparatus main body It is proposed to contain a drug. In this device, the developing device is downsized, the developer charging unit controls the developer charging amount, and the supply amount supplied to the developer conveying unit is stabilized, thereby stabilizing the conveyance amount and developing. The developer that has not contributed can be reliably recovered in the apparatus by the recovery means.
[0006]
[Problems to be solved by the invention]
However, it has been found that the above proposals also include the following problems.
[0007]
That is, it is found that a lot of scattered toner is generated in the vicinity of the developer charging unit and the collecting unit, and there is a possibility that the scattered toner adheres to the image carrier (photoconductor) and the image quality is deteriorated.
[0008]
Further, the developer adheres to a sealing member (blade) provided near the developer charging means, and the adhesion of the developer may cause local charging of the sealing member. Due to such a phenomenon, the traveling wave electric field is disturbed by the local charging of the sealing member, causing non-uniform thickness of the developer to be transported, and the developer cannot be transported smoothly and reliably.
[0009]
The present invention has been made in view of such points, and an object of the present invention is to provide image quality due to scattering of the developer when a mechanism (electric field curtain) for conveying the developer using a traveling wave electric field is used. An object of the present invention is to provide a developing device capable of preventing deterioration and local charging and transporting a developer smoothly and reliably, and an image forming apparatus provided with the developing device.
[0010]
[Means for Solving the Problems]
  In order to achieve the above object, according to the present invention, a developing device is arranged in a developing region facing an image carrier that carries an electrostatic latent image on its surface, and a plurality of arrays are arranged in a substrate with a predetermined interval. A developer conveying means for conveying the developer by a traveling wave electric field formed by applying a multiphase voltage to the formed electrode, and a surface of the developer conveying means so as to be in contact with or in close proximity to each other, At least one of a supply means for supplying the developer to the developer transport means and a recovery means for recovering the developer from the developer transport means; and contact between the developer transport means and the supply means or the recovery means; Covering means arranged to cover the periphery of at least one of the supply means and the recovery means in order to prevent the scattering of the developer generated in the proximity position. And the area | region which has electroconductivity is provided in the covering means corresponding to the circumference | surroundings of at least one of the said supply means and collection | recovery means.
[0011]
Due to this specific matter, the developer scattered in the vicinity of at least one of the supply means and the recovery means is supplied with the developer in the vicinity of the developer supply means, and the developer is recovered in the vicinity of the developer recovery means. Is carried out in the vicinity of the supply means or the recovery means, but it is confined by the covering means. For this reason, the scattered developer does not adhere to unnecessary portions of the image bearing member, and it is possible to prevent image deterioration and perform good image formation. In addition, the contamination of the image forming apparatus due to the scattering of the developer is prevented, and the operability and maintenance of the user can be improved. Further, since the covering means is provided with a conductive region, even if the toner adheres, the effect of suppressing local electrification on the covering means can be obtained. The coating means is locally remarkably charged due to the scattered developer adhering to the coating means, or the developer transportation from the supply means or the collection means is promoted, or the developer conveyance state is defective. Therefore, it is possible to stably supply, transport, and collect the developer.
[0012]
In particular, the following configuration can be cited as a more stable developer supply, transport, and recovery.
[0013]
That is, the voltage applying means for applying an arbitrary voltage is provided in the covering means.
[0014]
With this specific matter, even when the developer adheres to the coating unit and is remarkably charged, the coating unit can be neutralized, and the developer can be supplied, transported, and collected stably.
[0015]
In particular, the following configuration is listed as a means for improving image quality.
[0016]
  That is, a developer having a predetermined polarity is applied to the developer conveying means side so that the voltage applied to the covering means by the voltage applying means contributes to the development of the electrostatic latent image between the covering means and the developer conveying means. The value is set such that an electric field to be moved is generated.
[0017]
Due to this specific matter, the developer scattered in the vicinity of the developer supplying means is returned to the developer conveying means side without adhering to the coating means by the electric field between the coating means and the developer conveying means, and electrostatically The developer is transported by a developer transport means to be used for developing a latent image. For this reason, excessive developer adhesion to the coating means is suppressed, stable developer supply and conveyance steps are performed satisfactorily, and the image quality can be further improved.
[0018]
  The voltage applied to the coating means by the voltage application means is set to a value that generates an electric field for moving the developer having a predetermined polarity to the developer transport means side between the coating means and the developer transport means. In addition, an electric field is generated between the covering means and the supply means to move the developer having a polarity opposite to the developer having the predetermined polarity to the supply means side in order to contribute to the development of the electrostatic latent image. If the value is set to a small value, the developer scattered in the vicinity of the supply means is returned to the developer conveying means side without adhering to the covering means by the electric field between the coating means and the developer conveying means. The developer is transported by a developer transport means to be used for developing an electrostatic latent image. On the other hand, the developer scattered in the vicinity of the supply means contains a small amount of developer having a polarity opposite to the desired polarity (predetermined polarity) (developer that does not contribute to the development of the electrostatic latent image). However, these reverse polarity developers move to the supply means side, so that excessive developer adhesion to the coating means is suppressed, stable developer supply and conveyance processes are performed well, and image quality is further improved. It becomes possible to improve.
[0019]
When an AC voltage is superimposed on the voltage applied to the covering means by the voltage applying means, the covering means is effectively neutralized and the scattered developer is difficult to adhere to the covering means. As a result, a stable developer supply and conveyance process can be performed satisfactorily, and the image quality can be further improved.
[0020]
In addition, when the frequency of the alternating voltage applied to the coating means by the voltage applying means is set lower than the frequency of the voltage applied to the developer conveying means, the scattered developer is moved. It is possible to increase the time required for forming the electric field, and the stable supply and conveyance of the developer can be performed more favorably, and the image quality can be improved more effectively.
[0021]
In particular, when the covering means is provided with a vibration applying means for applying vibration to the covering means, by applying vibration to the covering means, accumulation of the developer adhesion amount on the covering means is reduced. Stable developer supply, conveyance, and recovery steps are performed satisfactorily, and the quality of the image can be further effectively improved.
[0022]
Further, the amplitude A (m) and the frequency f (Hz) of the vibration of the covering means are
A × f²> 10^Three
If the relationship is set so as to satisfy the above relationship, the removal of the developer by applying vibration is effectively performed, and the stable developer supply, conveyance, and recovery processes are performed satisfactorily. The quality can be further improved.
[0023]
In particular, the following configuration is listed as a means for effectively containing the scattered developer.
[0024]
  That is, an abbreviation of a supply unit and a recovery unit parallel to a line segment extending in a tangential direction of at least one of the peripheral surface of the supply unit and the peripheral surface of the recovery unit that are in contact with or close to the surface of the developer transport unit The covering means is configured to extend in a direction facing the developer conveying means from a line passing through the center so as to cover the developer conveying means, and the coating means and the developer conveying means extending in the direction facing the developer conveying means The gap is set to 0.05 mm or more.
[0025]
This specific matter makes it possible to effectively contain the scattered developer without hindering the flow of the developer on the developer conveying means.
[0026]
Further, when the image forming apparatus includes the above-described developing device, it is possible to prevent image deterioration and perform good image formation, high user operability and maintainability, and stable supply of developer. It is possible to provide an image forming apparatus capable of carrying and collecting.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0028]
<First Embodiment>
FIG. 1 shows an image forming apparatus provided with a developing device according to the first embodiment of the present invention. Inside the image forming apparatus X, a cylindrical photosensitive drum 1 as an image carrier is provided. Yes. A charging member 2, an exposure member 3, a developing device 4, a transfer member 5, a cleaning member 6, and a charge removal member 7 are sequentially arranged around the photosensitive drum 1. Further, between the photosensitive drum 1 and the transfer member 5, a paper conveyance path for conveying the paper P as a recording medium is provided. A fixing device 8 having a pair of upper and

lower fixing rollers

81, 81 is disposed on the downstream side of the photosensitive drum as viewed from the conveying direction of the sheet conveying path.
[0029]
In the electrophotographic process, an original image or an electrostatic latent image corresponding to data from a host computer (not shown) is formed on the photosensitive drum 1, and the electrostatic latent image is visualized by a developing device, and is printed on the paper P. To form an image.
[0030]
The photoconductive drum 1 has a photoconductive layer 12 formed on a substrate 11 and is rotatable from the charging member 2 according to the arrangement order of the members 3 to 7. First, the surface (photoconductive layer 12) of the photosensitive drum 1 is charged by the charging member 2 until it reaches a predetermined potential. The surface of the photosensitive drum 1 charged to a predetermined potential reaches the position of the exposure member 3 by the rotation of the photosensitive drum 1. The exposure member 3 is a writing means, and writes an image on the surface of the photosensitive drum 1 that is charged by light such as a laser based on image information. As a result, an electrostatic latent image is formed on the photosensitive drum 1. The surface of the photosensitive drum 1 on which the electrostatic latent image is formed reaches the position of the developing device 4 by the rotation of the photosensitive drum 1.
[0031]
In the developing device 4, the electrostatic latent image on the surface of the photosensitive drum 1 is developed as a toner image by the toner conveyed on the toner conveying member 41 (developer conveying means). The surface of the photosensitive drum 1 carrying the toner image reaches the position of the transfer member 5 by the rotation of the photosensitive drum 1.
[0032]
The transfer member 5 transfers the toner image on the surface of the photosensitive drum 1 onto the paper P. The toner image transferred from the photosensitive drum 1 onto the paper P is fixed on the paper P by the fixing device 8.
[0033]
The surface of the photosensitive drum 1 after the toner image is transferred reaches the position of the cleaning member 6 by the rotation of the photosensitive drum 1. The cleaning member 6 removes toner and paper dust remaining on the surface of the photosensitive drum 1. The surface of the photosensitive drum 1 cleaned by the cleaning member 6 reaches the position of the charge eliminating member 7 by the rotation of the photosensitive drum 1. The neutralizing member 7 removes the potential remaining on the surface of the photosensitive drum 1. One image formation is completed by the series of operations described above.
[0034]
As the photosensitive drum 1, for example, a metal drum such as aluminum is used as a base material 11, and a photoconductive layer 12 such as amorphous silicon (a-Si), selenium (Se), or an organic photo semiconductor (OPC) is formed on the outer peripheral surface thereof. Is formed in a thin film shape, but is not particularly limited.
[0035]
Examples of the charging member 2 include, but are not limited to, a configuration of a corona charger, a charging roller, a charging brush, or the like including a charging wire such as a tungsten wire, a metal shield plate, a grid plate, or the like. .
[0036]
Examples of the exposure member 3 include a semiconductor laser and a light emitting diode, but are not particularly limited.
[0037]
Examples of the transfer member 5 include a corona transfer device, a transfer roller, and a transfer brush, but are not particularly limited.
[0038]
Examples of the cleaning member 6 include a cleaning blade, but are not particularly limited.
[0039]
Examples of the charge removal member 7 include a charge removal lamp, but are not particularly limited.
[0040]
In the present embodiment, a constant interval is provided between the toner conveying member 41 and the photosensitive drum 1, and the electrostatic latent image on the surface of the photosensitive drum 1 is developed in a non-contact manner. The present invention is not limited to this, and may be configured to perform contact development by bringing the toner conveying member and the surface of the photosensitive drum into contact with each other.
[0041]
As shown in FIG. 2, the developing device 4 includes a casing 40, a toner conveying member 41, and a mixing paddle 42. The casing 40 accommodates toner inside. The mixing paddle 42 is for mixing the toner accommodated in the casing 40.
[0042]
The toner conveying member 41 has a belt shape that forms a substantially flat surface facing the developing area A of the photosensitive drum 1. In the present embodiment, the toner conveying member 41 has a belt shape, but the shape of the toner conveying member 41 is not limited to this, and may be, for example, a semicircular arc.
[0043]
Further, the toner conveying member 41 is disposed so as to be slightly inclined with respect to the vertical direction of the developing device 4 and to be substantially parallel to the tangent line of the developing area A on the surface of the photosensitive drum 1. In addition, a support member 43 that holds the toner conveying member 41 is provided on the surface opposite to the surface that conveys the toner so that the belt-shaped toner conveying member 41 can maintain the above-described arrangement.
[0044]
A supply member 44 (supply means) for supplying toner conveyed on the surface of the toner conveyance member 41 is provided at the lower end portion of the toner conveyance member 41. On the other hand, a collecting member 45 (collecting means) that collects toner on the surface of the toner conveying member 41 is provided at the upper end of the toner conveying member. Further, a covering member 46 (covering means) that covers the periphery of the supply member 44 and the recovery member 45 is provided, and the covering member 46 prevents the developer from scattering to the photosensitive drum 1 side. The covering member 46 includes a base body 46a provided integrally with the casing 40, and a conductive layered conductive portion 46b (conductive area) attached to the inside of the base body 46a. In this case, an insulating resin or a film is applied as the base 46a of the covering member 46, while a metal film such as aluminum or gold is formed on the base 46a by means such as vapor deposition as the conductive portion 46b. It may be a conductive resin or conductive film in which conductive particles are contained in the base 46a itself, or the covering member 46 may be a metal plate and exhibits conductivity. There is no particular limitation as long as it is present.
[0045]
In addition, a multiphase AC power supply 47 and a developing bias power supply 48 are connected to the toner conveying member 41 in series. Each of the supply member 44 and the recovery member 45 has a cylindrical shape, and is in contact with the surface of the belt-shaped toner conveying member 41 so as to be rotatable.
[0046]
The supply member 44 is for supplying the toner contained in the casing 40 to the toner conveying member 41, and the material thereof is not particularly limited. For example, silicone, urethane, EPDM (ethylene -Propylene-diene-methylene copolymer) and the like, and foamed rubber. Further, conductivity may be imparted by adding carbon black or an ionic conductive agent (voltage application is also possible). A contact pressure between the supply member 44 and the toner conveying member 41 and a voltage value applied to the supply member 44 may be set to appropriate values, and the supply member 44 may be added with a function of charging the toner. Alternatively, for example, a thin blade (the same material as the supply member 44 can be used) may be provided in front of the supply member 44 to charge the toner.
[0047]
The collecting member 45 is for collecting toner that does not contribute to the development of the electrostatic latent image on the photosensitive drum 1 and returning it to the developing device 4, and the material thereof is not particularly limited. The same supply member 44 can be used.
[0048]
The support member 43 is for holding the belt-shaped toner conveying member 41 facing the developing area A of the photosensitive drum 1, and the configuration thereof is not particularly limited. For example, ABS (acrylonitrile-butadiene-styrene: acrylonitrile butadiene styrene) resin can be used.
[0049]
The toner conveying member 41 conveys toner by an electric field curtain action. As shown in FIG. 3, traveling wave generating electrodes 41b,... For generating an electric field curtain action are formed on a base material 41a made of an insulating layer. A plurality of sets of four sets are sequentially arranged. The surface side of the toner conveying member 41 is covered with a surface protective layer 41c. Then, an electric field curtain is generated in a direction parallel to the surface of the toner conveying member 41 by applying a multi-phase AC voltage to the electrodes 41b,. As a result, the toner is conveyed to the developing area A by the electric field curtain action.
[0050]
Specific examples of the toner conveying member 41 include, for example, a base material 41a: polyimide (thickness 25 μm), traveling wave generating electrode 41b: copper (thickness 18 μm), surface protective layer 41c: polyimide (thickness 25 μm), and the like. A configuration can be mentioned. The traveling wave generating electrode 41b is a micro electrode having a width of 40 μm, and is arranged in parallel to each other while maintaining an interval of 100 dpi (dot per inch) to 300 dpi, that is, a pitch of about 254 μm to 85 μm. . In this embodiment, four traveling wave generating electrodes 41b,... Are set as one set, and for each of these sets of traveling wave generating electrodes 41b,. Are applied, and a traveling wave electric field is formed on the traveling wave generating electrodes 41b,..., But is not limited to this. An alternating voltage may be applied. Further, 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 10 kHz, but for these voltage values and frequencies, An appropriate value may be set according to the shape of the traveling wave generating electrode element, the toner conveyance speed, the toner used material, and the like, and is not particularly limited.
[0051]
Here, the cause of toner scattering near the supply member 44 or the recovery member 45 will be described.
[0052]
The supply member 44 or the recovery member 45 rotates at a rotational peripheral speed of about several tens mm / s to 100 to 200 mm / s.
[0053]
On the other hand, the speed of the toner moving on the toner conveying member 41 by the traveling wave electric field is very fast, and the characteristics of the toner (specific charge, particle size, etc.) and the conditions of the voltage applied to the toner conveying member 41 (frequency and peak-to-peak voltage). Etc.) and the structural conditions of the toner conveying member 41 (interelectrode pitch, surface protective layer 41c thickness, etc.), but move at a speed of several tens mm / s to several thousand mm / s.
[0054]
Therefore, since a toner layer having a large moving speed difference exists in the vicinity of the closest contact point between the supply member 44 or the recovery member 45 and the toner conveying member 41, it is considered that scattering is likely to occur due to collision between toners. In the toner conveying member region (for example, in the vicinity of the developing region A) where the supply member 44 and the collecting member 45 are not present, the toner moving speed does not vary greatly, so that toner scattering hardly occurs.
[0055]
Therefore, in the present embodiment, the toner scattered around the supply unit 44 and the recovery unit 45 is supplied to the toner in the vicinity of the supply unit 44 or when the toner is recovered in the vicinity of the recovery unit 45. Although it is likely to be scattered in the vicinity of the supply unit 44 and the recovery unit 45, it is confined in the casing 40 by the covering member 46. For this reason, the scattered toner does not adhere to unnecessary portions of the photosensitive drum 1, and image formation can be prevented and good image formation can be performed.
[0056]
In addition, it is possible to prevent in-machine contamination of the image forming apparatus X due to the scattering of toner, and it is possible to improve the operability and maintainability of the user.
[0057]
Further, since the conductive portion 46b is provided inside the base body 46a of the covering member 46, an effect of suppressing local charging at the covering member 46 can be obtained even if toner adheres. Therefore, when the covering member is insulative, the scattered toner adheres to the covering member, and the covering member is locally remarkably charged. This facilitates the scattering of toner from the supply means 44 and the collecting means 45. In addition, no trouble is caused in the toner conveyance state, and stable toner supply, conveyance, and recovery can be performed.
[0058]
Further, by providing the above-described developing device 4 in the image forming apparatus X, it is possible to prevent the image deterioration and perform good image formation, high user operability and maintainability, and stable supply and conveyance of the developer. Therefore, it is possible to provide an image forming apparatus capable of performing recovery.
[0059]
<First Modification>
In the present embodiment, the conductive portion 46b is only provided inside the base body 46a of the covering member 46. However, as shown by a virtual line (two-dot chain line) in FIG. A first power source 46c and a second power source 46d may be provided as voltage applying means for applying an arbitrary voltage to the conductive portion 46b of the covering member 46 that covers each of the covering members 46. In this case, when the covering member 46 is charged by the adhesion of the toner and the charged charge is accumulated, it is possible to remove the charged charge, thereby effectively suppressing the charging of the covering member 46. Thus, stable toner supply, conveyance and recovery can be performed.
[0060]
<Second Modification>
Further, as an applied voltage applied to the conductive portion 46b of the covering member 46 by the first power source 46c and the second power source 46d (voltage applying means), toner having a desired polarity is applied between the covering member 46 and the toner conveying member 41. You may set to the value which the electric field moved to the toner conveyance member 41 side produces. In this case, the toner scattered in the vicinity of the supply member 44 and the recovery member 45 is returned to the toner conveying member 41 side without being attached to the covering member 46 due to the electric field between the covering member 46 and the toner conveying member 41, The toner is conveyed by the toner conveying member 41 to be used for developing the electrostatic latent image. Therefore, excessive toner adhesion to the covering member 46 is suppressed, whereby stable toner supply, conveyance, and recovery steps are performed satisfactorily, and the image quality can be further improved.
[0061]
Specifically, when negative polarity toner is used, voltage setting as shown in FIG. 5 is performed. An AC voltage of 0 to −400 V is applied to the toner conveying member 41, and a voltage of −500 V is applied to the supply member 44. At this time, a voltage of −600 V is applied to the covering member 46 on the supply member 44 side. In such a setting, since an electric field is generated between the covering member 46 and the toner conveying member 41 so as to move the negative polarity toner toward the toner conveying member 41, the scattered toner is again on the toner conveying member 41 side. Thus, toner adhesion to the covering member 46 side can be suppressed.
[0062]
On the other hand, the covering member 46 on the collecting member 45 side can have the same configuration. For example, a voltage of 0 to −400 V is applied to the toner conveying member 41 and a voltage of +100 V is applied to the collecting member 45 as shown in FIG. At this time, a voltage of −600 V is applied to the covering member 46 on the collecting member 45 side. Even in such a setting, an electric field is generated between the covering member 46 and the toner conveying member 41 so as to move the negative polarity toner toward the toner conveying member 41, so that the above-described effects can be obtained. .
[0063]
<Third Modification>
Then, as a voltage to be applied to the covering member 46 that covers the supply member 44, a toner having a predetermined polarity to contribute to the development of the electrostatic latent image on the photosensitive drum 1 between the covering member 46 and the toner conveying member 41. Is set to a value that generates an electric field that moves the toner toward the toner conveying member 41 side, and toner having a polarity opposite to that of the predetermined polarity between the covering member 46 and the supplying member 44 is supplied to the supplying member 44 side. It may be set to a value that generates an electric field to be moved to.
[0064]
Specifically, voltage setting as shown in FIG. That is, an AC voltage of 0 to −400 V is applied to the toner conveying member 41, and a voltage of −500 V is applied to the supply member 44. At this time, a voltage of −400 V is applied to the covering member 46 on the supply member 44 side. In such a setting, an electric field is generated between the covering member 46 and the toner conveying member 41 so as to move the negative polarity toner toward the toner conveying member 41, and between the covering member 46 and the supply member 44. In the meantime, an electric field is generated to move the reverse polarity toner to the supply member 44 side.
[0065]
In this case, the toner scattered in the vicinity of the supply member 44 is returned to the toner conveying member 41 side without being attached to the covering member 46 due to the electric field between the covering member 46 and the toner conveying member 41, and The toner is conveyed by the toner conveying member 41 to be used for development. Basically, only the toner having the desired polarity moves from the supply member 44 to the toner conveying member 41, and the toner of the reverse polarity does not move to the toner conveying member 41, but again the casing of the developing device 4. Although the amount of toner is returned to 40, a small amount of toner having a reverse polarity may also move. At this time, the toner scattered in the vicinity of the supply member 44 contains a small amount of toner having a reverse polarity to the desired polarity, but the toner having the reverse polarity moves to the supply member 44 side. Therefore, excessive toner adhesion to the covering member 46 can be suppressed. This effect also has the effect of reducing the amount of reverse polarity toner in the toner moving on the toner conveying member 41 (toner used in the developing process). That is, it is possible to improve the efficiency of positively returning the reverse polarity toner to the supply member 44 side without moving the reverse polarity toner to the toner conveyance member 41 side by the supply member 44 and returning it to the casing 40. Therefore, the ratio of the reverse polarity toner in the toner used in the developing process is reduced by moving on the toner conveying member 41, and the ground cover of the photosensitive drum 1 by the reverse polarity toner (originally a non-image portion). The toner of the photosensitive drum 1 due to the toner adhering to the region is often the main cause of reverse polarity toner.) And more stable toner supply, conveyance, development, and recovery processes can be performed. Therefore, the image quality can be further improved.
[0066]
<Fourth Modification>
Furthermore, an AC voltage may be superimposed on the voltage applied to the covering member by the first power supply 46c and the second power supply 46d (voltage applying means).
[0067]
Specifically, voltage setting as shown in FIG. That is, a voltage of 0 to −400 V is applied to the toner conveying member 41, and a voltage of −500 V is applied to the supply member 44. At this time, an AC voltage having a peak-to-peak voltage of 600 V is superimposed on a DC voltage of −300 V on the covering member 46 (conductive portion 46 b) on the supply member 44 side. That is, a voltage of 0 V to −600 V is applied to the covering member 46. For example, when a voltage of −600 V is applied to the supply member 44, a sufficient electric field for returning the negative polarity toner to the toner conveying member 41 side is formed, and when 0 V is applied, reverse polarity toner is supplied to the supply member 44. The electric field for returning to the side is sufficiently formed, and the operation of the above-described third modification can be realized more effectively.
[0068]
The reason for this will be described in more detail.
[0069]
If the voltage applied to the supply member 44 is too large, the pressing force of the toner due to the electric field from the supply member 44 to the toner conveying member 41 becomes strong, and the toner can be moved by the traveling wave electric field on the toner conveying member 41. It can be difficult. Conversely, if the voltage applied to the supply member 44 is too small, sufficient supply of toner from the supply member 44 to the toner transport member 41 cannot be performed, and the necessary toner transport amount may not be obtained. Therefore, the voltage applied to the supply member 44 has an appropriate value. That is, when the voltage applied to the covering member 46 is only a DC voltage, the voltage range that can be applied to the covering member 46 is a value between the voltage applied to the toner conveying member 41 and the voltage applied to the supply member 44. There is a need to. For this reason, when the potential difference between the supply member 44 and the toner conveying member 41 is small, it may not be possible to secure a sufficient electric field strength for returning the scattered toner to the toner conveying member 41 and the supply member 44. However, according to the configuration of this modification, the electric field for returning the desired polarity toner to the toner conveying member 41 and the electric field for returning the opposite polarity toner to the supply member 44 can be increased, and the adhesion of scattered toner is effectively suppressed. it can.
[0070]
Also, when charging due to toner adhesion to the covering member 46 occurs, it is preferable to superimpose an AC voltage to improve the charge eliminating effect of the covering member 46. This effect can also be applied to the recovery member 45.
[0071]
Further, it is desirable that the frequency of the voltage applied to the covering member 46 is lower than the frequency of the voltage applied to the toner conveying member 41. For example, it is desirable to set it to 1/2 or less of the voltage frequency applied to the toner conveying member 41. By setting such conditions, it is possible to increase the electric field formation time for moving the scattered toner. Further, depending on the balance with the voltage phase of the toner conveying member 41, there is a possibility that the potential difference between the covering member 46 and the toner conveying member 41 is minimized, and the scattered toner is moved to a desired location. There is a risk that the electric field will be weakened. However, according to the configuration of the present modification, the above problem can be avoided, which is more preferable.
[0072]
In short, according to the configuration of the present modification, accumulation of toner adhering to the covering member 46 can be suppressed by superimposing an AC voltage, and charging due to toner adhesion can be effectively eliminated, and more stable toner supply, The conveyance and recovery steps are performed well, and the image quality can be further improved.
[0073]
<Second Embodiment>
Next, a second embodiment of the present invention will be described with reference to FIG.
[0074]
In this embodiment, means for applying vibration to the covering member is provided. In addition, the structure other than a covering member is the same as that of the case of 1st Embodiment, The same code | symbol is attached | subjected about the same part and the description is abbreviate | omitted.
[0075]
That is, in this embodiment, as shown in FIG. 8, the covering member 9 is made of a PET (polyethylene terephthalate) film of about 100 μm, and provided with vibration applying means 91 for applying vibration to the covering member 9. As the vibration applying means 91, for example, a stacked piezo element or the like can be used. One end of the piezo element is fixed to the casing 40, and the other end is fixed to the covering member 9 side.
[0076]
As a result, even if the scattered toner adheres to the covering member 9, it is eliminated by the vibration of the covering member 9, and accumulation of the adhering toner on the covering member 9 can be prevented. By such an action, charging of the covering member 9 due to toner accumulation on the covering member 9 is suppressed, and stable toner supply, conveyance, and recovery steps can be performed, and good image formation can be obtained.
[0077]
<Modification>
In the present embodiment, the vibration is simply applied to the covering member 9. However, the vibration amplitude A (m) and the frequency f (Hz) of the covering member 9 are set as conditions for applying the vibration.
A × f²> 10^Three
It is even more preferable to set so as to satisfy the relationship.
[0078]
That is, assuming that the maximum amplitude of the covering member 9 is A (m), the frequency is f (Hz), and the sinusoidal vibration is performed, the displacement amount x (m) of the covering member 9 with respect to the time t (s) is It is expressed by the following formula.
[0079]
x = A × sin (2 × π × f × t)
Therefore, the acceleration a of the covering member 9 is
a = −4 × π²× f²× A × sin (2 × π × f × t)
It becomes.
[0080]
In order to remove the toner adhering to the covering member 9, a force that overcomes the adhesion force of the toner adhering to the covering member 9 (m × a, where m is the toner mass and a is the acceleration of the covering member 9). Must work. That is, A × f determined by the amplitude A and the frequency f of the covering member 9 that determines the acceleration a.²By increasing the value, the ability to remove toner attached to the covering member 9 is improved.
[0081]
Therefore, by changing the voltage and frequency applied to the piezo element, the above A × f²When the value was changed and the influence on image formation by toner adhesion to the covering member 9 was examined, the results shown in Table 1 were obtained.
[0082]
[Table 1]

In Table 1, A × f²When the value is 1000 or more, the adhered toner is efficiently removed by the vibration of the covering member 9, and the charging of the covering member 9 due to the toner adhesion and the influence on the toner conveyance and developing process due to the accumulation of the adhered toner can be suppressed.
[0083]
Thereby, stable supply, conveyance, and recovery steps of the developer can be performed satisfactorily, and the image quality can be further improved.
[0084]
<Other variations>
In the second embodiment, an example in which the covering member 9 is made conductive and an arbitrary voltage is not applied has been described. However, the present invention is not limited to this. If the means described in the first embodiment are used in combination, better image formation can be performed.
[0085]
<Third Embodiment>
Next, a third embodiment of the present invention will be described with reference to FIG.
[0086]
In this embodiment, the arrangement state of the covering member with respect to the toner conveying member is defined. In addition, the structure other than a covering member is the same as that of the case of 1st Embodiment, The same code | symbol is attached | subjected about the same part and the description is abbreviate | omitted.
[0087]
That is, in this embodiment, as shown in FIG. 9, the covering member 10 extends in the tangential direction S (tangential direction) between the peripheral surface of the supply member 44 and the peripheral surface of the collection member 45 that are in contact with the surface of the toner conveying member 41. A line H is formed so as to extend in a direction (upward in FIG. 9) facing the toner conveying member 41 from a parallel line H passing through substantially the center of the supply member 44 and the collecting member 45, and to cover the toner conveying member 41. The gap K between the covering member 10 extending in the direction facing the toner conveying member 41 and the toner conveying member 41 is set to 0.05 mm or more.
[0088]
In this case, reducing the gap K between the covering member 10 and the toner conveying member 41 is effective in preventing leakage of scattered toner to the outside (outside the covering member 10). However, in the method of transporting toner in the form of a cloud by a traveling wave electric field as in the present invention, a general one-component developing method (a thin layer toner is formed on a toner carrier such as a rubber roller or a metal roller) ) Is thicker than the toner layer. Therefore, if the gap K between the covering member 10 and the toner conveying member 41 is too small, the toner conveying becomes an obstacle.
[0089]
Thus, as a result of studying the gap K that does not interfere with toner conveyance by setting various toner characteristics and traveling electric field forming conditions, it was found that good toner conveyance can be achieved by setting the gap K to 50 μm or more.
[0090]
Further, in the direction in which the gap K between the covering member 10 and the toner conveying member 41 is widened, in the supply member 44 and the collecting member 45 covered by the covering member 10, the peripheral surfaces of the supplying member 44 and the collecting member 45 are the toner conveying member. The covering member 10 covers the supply member 44 and the recovery member 45 to a position facing the surface 41. Specifically, for example, a parallel line H passing through the approximate center of the supply member 44 parallel to the tangent line S to the toner conveying member 41 of the supply member 44, for example. It is sufficient to cover the toner conveying member 41 side (upper side in FIG. 9).
[0091]
The reason for this will be described with reference to FIG. 9, taking as an example the case where the supply member 44 and the recovery member 45 are in the form of rollers.
[0092]
From the position closest to the toner conveying member 41 to a position approximately half the diameter thereof (a position intersecting a parallel line H passing through the center of the supplying member 44), the toner supplying member 44 and the collecting member with respect to the toner conveying member 41 Reference numeral 45 denotes a shape facing the toner conveying member 41. Therefore, in this region, an electric field for attracting one of the

members

44 and 45 is formed between the supply member 44 and the recovery member 45 and the toner transport member 41 without floating the scattered developer. . That is, not only the scattered toner hiding effect by the covering member 10 but also the supply member 44 and the recovery member 45 themselves have a function of controlling the scattered toner. However, the toner scattered by the action of the electric field between the toner conveying member 41 and the toner conveying member 41 in a region away from a position substantially half the diameter of the supply member 44 and the collecting member 45, that is, in a region not facing the toner conveying member 41. There is a case where only the hiding effect by the covering member 10 can be expected, and a sufficient hiding effect of the scattered toner cannot be obtained. Accordingly, in order to conceal the scattered toner, the upper limit of the gap K between the covering member 10 and the toner conveying member 41 is set so that the peripheral surfaces of the supply member 44 and the collecting member 45 are positioned to face the toner conveying member 41. Is desirable.
[0093]
According to the above configuration, the toner flow on the toner conveying member 41 is not hindered, and the scattered toner can be effectively contained.
[0094]
【The invention's effect】
  As described above, the coating means that covers the periphery of at least one of the supply means and the recovery means in order to prevent the scattering of the developer that occurs at the position where the developer conveyance means and the supply means or the recovery means come into contact or close to each other. By providing a conductive region, it is possible to prevent the developer scattered in the vicinity from being confined by the coating means and attached to unnecessary portions of the image bearing member, thereby preventing image deterioration and good image quality. In addition to being able to perform the formation, it is possible to improve the operability and maintenance of the user by preventing contamination of the image forming apparatus due to the scattering of the developer. Furthermore, by providing a region having conductivity in the coating unit, an effect of suppressing local charging in the coating unit due to toner adhesion can be obtained, and stable supply, conveyance, and recovery of the developer can be performed.
[0095]
In particular, by providing a voltage applying means for applying an arbitrary voltage to the coating means, the coating means can be neutralized when the developer is significantly charged due to adhesion of the developer to the coating means, and stable supply and transport of the developer. Can be recovered.
[0096]
  In particular, an electric field is generated that moves the developer having a predetermined polarity to the developer conveying means side so that the voltage applied to the covering means contributes to the development of the electrostatic latent image between the covering means and the developer conveying means. By setting to such a value, the developer scattered in the vicinity of the supply unit is returned to the developer conveying unit side without adhering to the coating unit, so that excessive developer adhesion to the coating unit is suppressed and stable development is performed. The quality of the image can be further improved by satisfactorily supplying the agent and carrying it.
[0097]
  Further, an electric field is generated for moving the developer having a predetermined polarity to the developer conveying means side so that the voltage applied to the covering means contributes to the development of the electrostatic latent image between the covering means and the developer conveying means. By setting the value such that an electric field for moving the developer having the opposite polarity to the predetermined developer to the supply means side is generated between the coating means and the supply means. The developer that scatters in the vicinity of the means is transported back to the developer conveying means side without adhering to the covering means, while the developer of the opposite polarity that is scattered in the vicinity of the supplying means is moved to the supplying means side to be covered. Excess developer adhesion to the surface can be suppressed, and a stable developer supply and conveyance process can be performed satisfactorily to further improve the image quality.
[0098]
Then, by superimposing an AC voltage on the voltage applied to the coating means, the coating means is effectively neutralized, making it difficult for the scattered developer to adhere to the coating means, and providing a stable developer supply and conveyance process. The quality of the image can be further improved.
[0099]
Moreover, by setting the frequency of the alternating voltage applied to the coating means to be lower than the frequency of the applied voltage to the developer conveying means, it is possible to increase the electric field formation time, and to supply and convey the developer stably. The image quality can be improved more effectively.
[0100]
In particular, by providing vibration applying means on the coating means, accumulation of the amount of developer attached to the coating means is reduced, and stable developer supply, conveyance, and recovery processes are performed well to further improve image quality. Can be improved.
[0101]
Further, the amplitude A (m) and the frequency f (Hz) of the vibration of the covering means are
A × f²> 10^Three
By setting so as to satisfy the above relationship, it is possible to effectively remove the developer by applying vibration, and to improve the image quality further by performing stable developer supply, conveyance and recovery processes. it can.
[0102]
  In particular, the abbreviations of the supply means and the recovery means parallel to a line segment extending in the tangential direction of at least one of the peripheral surface of the supply means and the peripheral surface of the recovery means that come into contact with or close to the surface of the developer transport means. By setting the gap between the covering means covering the developer conveying means extending in the direction facing the developer conveying means from the line passing through the center and the developer conveying means to be 0.05 mm or more, the developer conveying means Thus, the scattered developer can be effectively contained without hindering the flow of the developer.
[0103]
Furthermore, by providing the above-described developing device in the image forming apparatus, it is possible to prevent image deterioration and perform good image formation, high user operability and maintainability, and stable developer supply, conveyance, and recovery. It is possible to provide an image forming apparatus capable of performing the above.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a schematic configuration of an image forming apparatus using an electrophotographic system to which a developing device according to a first embodiment of the present invention is applied.
FIG. 2 is a schematic diagram showing the configuration of the developing device.
FIG. 3 is a schematic diagram illustrating the configuration of a toner conveying member.
FIG. 4 is a waveform diagram showing a voltage waveform similarly applied to the toner conveying member.
FIG. 5 is an explanatory diagram of voltage conditions applied to the developing device according to a second modification of the first embodiment.
FIG. 6 is an explanatory diagram of voltage conditions applied to the developing device according to a third modification of the first embodiment.
FIG. 7 is an explanatory diagram of voltage conditions applied to the developing device according to a fourth modification of the first embodiment.
FIG. 8 is a schematic diagram showing a schematic configuration of a developing device according to a second embodiment of the present invention.
FIG. 9 is a schematic diagram illustrating a schematic configuration of a developing device according to a third embodiment of the present invention.
[Explanation of symbols]
1 Photosensitive drum (image carrier)
4 Development device
41 Toner conveying member (developer conveying means)
41a base material
41b Traveling wave generating electrode (electrode)
44 Supply member (supply means)
45 Collection member (collection means)
46, 9, 10 Coating member (coating means)
46b Conductive part (region having conductivity)
46c 1st power supply (voltage application means)
46d Second power source (voltage applying means)
91 Vibration imparting means
A Development area
K gap
T Toner (Developer)
X image forming device

Claims

The electrostatic latent image is formed in the development area facing the image carrier carrying the electrostatic latent image on its surface, and is formed by applying a multiphase voltage to a plurality of electrodes arranged at predetermined intervals in the substrate. Developer transport means for transporting the developer by a traveling wave electric field,
At least one of a supply means for supplying the developer to the developer conveying means and a collecting means for recovering the developer from the developer conveying means provided so as to be in contact with or close to the surface of the developer conveying means. On the other hand,
In order to prevent the scattering of the developer generated at the contact or proximity position between the developer conveying means and the supply means or the recovery means, it is arranged so as to cover the periphery of at least one of the supply means and the recovery means. Covering means, and
2. A developing apparatus according to claim 1, wherein the covering means corresponding to the periphery of at least one of the supply means and the recovery means is provided with a conductive region.

In the developing device according to claim 1,
A developing device, wherein the coating means is provided with voltage applying means for applying an arbitrary voltage.

In the developing device according to claim 2,
The voltage applied to the covering means by the voltage applying means moves the developer having a predetermined polarity to the developer conveying means side so as to contribute to the development of the electrostatic latent image between the covering means and the developer conveying means. A developing device characterized in that the value is set such that an electric field is generated.

In the developing device according to claim 2 ,
The voltage applied to the coating unit by the voltage applying unit is an electric field that moves a developer having a predetermined polarity to the developer transport unit side to contribute to the development of the electrostatic latent image between the coating unit and the developer transport unit. It is set to occur such a value, and set to a value such electric field is generated to move to the supply means side a developer having a polarity opposite to a developer having the predetermined polarity between the covering means and the supply means A developing device.

In the developing device according to any one of claims 2 to 4,
A developing device characterized in that an alternating voltage is superimposed on a voltage applied to the covering means by the voltage applying means.

In the developing device according to claim 5,
The developing device, wherein the frequency of the alternating voltage applied to the coating means by the voltage applying means is set lower than the frequency of the voltage applied to the developer conveying means.

Progression formed by applying a multiphase voltage to a plurality of electrodes arranged in a developing region facing a surface of an image carrier that carries an electrostatic latent image on the surface and arranged at predetermined intervals in the substrate. Developer conveying means for conveying the developer by a wave electric field;
At least one of a supply means for supplying the developer to the developer conveying means and a collecting means for recovering the developer from the developer conveying means provided so as to be in contact with or close to the surface of the developer conveying means. On the other hand,
Covering means arranged to cover the periphery of at least one of the supply means and the recovery means,
The developing device, wherein the covering means includes a vibration applying means for applying vibration to the covering means.

In the developing device according to claim 7,
2. A developing device according to claim 1, wherein the covering means corresponding to the periphery of at least one of the supplying means and the collecting means is provided with a conductive region.

In the developing device according to claim 7,
The amplitude A (m) and the frequency f (Hz) of the vibration of the covering means are
A × f ² > 10 ³
A developing device characterized by being set so as to satisfy the above relationship.

In the developing device according to any one of claims 1 to 9,
The covering means includes a supply means and a recovery means parallel to a line segment extending in a tangential direction of at least one of the peripheral surface of the supply means and the peripheral surface of the recovery means facing or close to the surface of the developer conveying means. Is configured to extend in a direction facing the developer conveying means rather than a line passing through substantially the center of the developer covering means and to cover the developer conveying means,
A developing device characterized in that a gap between the coating means extending in a direction facing the developer conveying means and the developer conveying means is set to 0.05 mm or more.
The covering means is configured so that at least one of the peripheral surface of the supply means and the peripheral surface of the recovery means is covered to a position facing the developer conveying means,
A developing device characterized in that a gap between the covering means and the developer conveying means is set to 0.05 mm or more.

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