JP3850464B2 - Image forming apparatus - Google Patents

Description

【００５７】
ここで、ｄ_t ：帯電微粒子等の層厚（ｍ）
ｄ_o ：画像情報形成体の膜厚（ｍ）
ε_t ：帯電微粒子等の比誘電率
ε_o ：画像情報形成体の比誘電率
ｇ ：空隙の大きさ（ｍ）
である。また、Ｖ_g による空隙電界強度Ｅ_g は、数１を用いて、数２のように表される。
【００５８】
【数２】

【００５９】
数１及び数２で表される空隙に印加される電圧及び空隙電界強度は、実際の構成においては電源手段によって印加されるクリーニング電圧と画像情報形成体上のトナー等の帯電微粒子を含めたクリーニング領域での表面電位の電位差によって求められる。即ち、この電位差が大きければ、トナー等の帯電微粒子に作用するクーロン力は大きくなる。トナー等の帯電微粒子に作用するクーロン力Ｆ_e は、トナー等の帯電微粒子の持つ電荷をｑ、空隙電界強度をＥ_g とすると数３で表され、またトナー等の帯電微粒子と画像情報形成体上のトナー等の帯電微粒子を含めたクリーニング領域での表面電位との反発力、鏡像力、ｖａｎ ｄｅｒ Ｗａａｌｓ力が作用する。
【００６０】
【数３】

【００６１】
なお、数３は、クリーニング領域に直流バイアス電圧を印加した場合であり、交流バイアス電圧又は直流バイアス電圧に交流バイアス電圧を重畳した振動電圧を印加した場合には、クーロン力のみならず力学的な力（トナー等の帯電微粒子同志の衝突による衝撃力など）も作用する。また、クーロン力も前述した直流バイアス電圧のみによる場合と異なり、前記振動電圧のピーク間電圧から求められる振動電界によるクーロン力が作用する。
【００６２】
本出願人は、クリーニングにおけるこの振動電界中でのトナー等の帯電微粒子の飛翔を最もよく表している衝突雪崩モデル（Ｃｏｌｌｉｓｉｏｎ Ｃａｓｃａｄｅ Ｍｏｄｅｌ）を、本発明のクリーニング手段に適用した。この衝突雪崩モデルは、富士ゼロックス社の柳田氏らによって現像手段に適用された。このモデルは、最初にトナー担持体から画像情報形成体に向かってトナー等の帯電微粒子が飛翔し、交流バイアス電圧によってトナー担持体に戻る逆飛翔の帯電微粒子が、トナー担持体上の帯電微粒子に衝突し、力学的な力で前記帯電微粒子をトナー担持体から剥離させることで、画像情報形成体に前記帯電微粒子が飛翔するというものである。
【００６３】
このモデルをクリーニングに適用した場合では、クリーニングされる球形のトナー等の帯電微粒子１個が空気中を電界によって運動する場合の運動方程式を空気の粘性抵抗も考慮して、数４のように表される。この場合、画像情報形成体と回転体の回転中心を結ぶ方向の時間ｔでの位置をｘ（ｔ）としている。
【００６４】
【数４】

【００６５】
ここで、ｑ ：帯電微粒子１個の電荷量（Ｃ）
ｍ ：帯電微粒子１個の質量（ｋｇ）
ｒ ：帯電微粒子１個の半径（ｍ）
η ：空気の粘性係数（Ｐａ・ｓ）
ｆ ：交流バイアス電圧の周波数（Ｈｚ）
Ｅ ：クリーニング領域でのクリーニング電界（Ｖ／ｍ）
Ｅ_{A C} ：交流バイアス電圧によるクリーニング電界（Ｖ／ｍ）
Ｅ_{D C} ：直流バイアス電圧によるクリーニング電界（Ｖ／ｍ）
である。
【００６６】
この衝突雪崩モデルでは、トナー等の帯電微粒子の飛翔は、特定のバイアス印加条件で効率よく起こることになり、これが飛翔の共鳴現象と呼ぶことができる。数４をｘ（ｔ）について解くと、数５のようになる。
【００６７】
【数５】

【００６８】
ここで、τ ：減衰係数 ｍ／（６πηｒ）
Ｃ ：クリーニング領域での空隙の静電容量（Ｆ）
Ｖ_{A C} ：クリーニング電圧の交流バイアス電圧のピーク間電圧（Ｖ ）
Ｖ_P ：画像情報形成体のクリーニング領域での表面電位（Ｖ）
Ｖ_{D C} ：クリーニング電圧の直流バイアス電圧（Ｖ）
ε₀ ：真空中の誘電率（Ｆ／ｍ）
である。
【００６９】
この数５は、画像情報形成体と回収体との距離、即ち空隙が、交流バイアス電圧の周波数やクリーニング電圧の大きさ等の種々のパラメータに依存していることを表している。ここで示すトナー等の帯電微粒子の飛翔する共鳴（以下、飛翔共鳴と呼ぶ）条件は、数４及び数５に示したパラメータが各々影響を及ぼし合い複雑である。
【００７０】
そこで、トナー等の帯電微粒子がクリーニング電圧の交流バイアス電圧の半周期の時間ｔ₀ で、回収体から画像情報形成体上へ移動する時に飛翔共鳴が起こるとすると、このときの交流バイアス電圧の周波数、即ち飛翔共鳴周波数ｆ₀ を用いて、時間ｔ₀ は、数６のように表される。
【００７１】
【数６】

【００７２】
飛翔共鳴が起こる時のｘ（ｔ₀ ）は、画像情報形成体と回収体との空隙ｇに等しい。従って数５は、数７のようになる。
【００７３】
【数７】

【００７４】
この数７から、トナー等の帯電微粒子の飛翔が、飛翔共鳴周波数ｆ₀ で印加したクリーニング電圧の交流バイアス電圧の周波数に依存する。そして、前記周波数、トナー等の帯電微粒子の電荷量あるいは比電荷が一定ならば、クリーニング電圧のバイアス電圧の大きさ、画像情報形成体上の帯電微粒子を含めたクリーニング領域での表面電位といった飛翔共鳴のバイアス印加条件に依存する。
【００７５】
例えば、一例として本発明においては、図２に示すように、交流バイアス電圧の周波数が２．５ｋＨｚ〜１２ｋＨｚの交流バイアス電圧を持つクリーニング電圧を印加すると、トナー等の帯電微粒子の飛翔が効率よく行われ、良好なクリーニング性が得られる。
【００７６】
また、数７によると、トナー等の帯電微粒子の飛翔効率やクリーニング特性は画像情報形成体のクリーニング領域での表面電位と回収体あるいは第１の回収体に印加するクリーニング電圧の直流バイアス電圧との電位差ΔＶ、クリーニング電圧の交流バイアス電圧のピーク間電圧にも依存することを示している。即ち、同じ周波数のクリーニング電圧の交流バイアス電圧を印加していても、画像情報形成体のクリーニング領域での表面電位と回収体あるいは第１の回収体に印加するクリーニング電圧の直流バイアス電圧との電位差ΔＶが飛翔共鳴の条件に一致しなければ、良好なクリーニング性が得られない場合がある。逆に、同じ周波数、同じ電位差であっても、クリーニング電圧の交流バイアス電圧のピーク間電圧が、特定の大きさをもって印加されなければ、飛翔共鳴の条件に一致せず、良好なクリーニング性が得られないことになる。
【００７７】
このことは、クリーニング電圧を印加して、回収体あるいは第１の回収体でトナー等の帯電微粒子をクリーニングする場合に、飛翔共鳴のバイアス印加条件に飛翔閾値電圧が存在するということである。このバイアス印加条件の飛翔閾値電圧は、前述した画像情報形成体のクリーニング領域での表面電位と回収体あるいは第１の回収体に印加するクリーニング電圧の直流バイアス電圧との電位差、クリーニング電圧の交流バイアス電圧のピーク間電圧に関連する。
【００７８】
まず、前者は画像情報形成体のクリーニング領域における直流電位を規定するもので、トナー等の帯電微粒子の帯電極性によって異なる。本発明のクリーニング手段は、画像情報形成体表面もしくは画像情報形成体上のトナー等の帯電微粒子の少なくとも一方、あるいは円筒状又はシート状部材表面もしくは前記円筒状又はシート状部材表面に付着したトナー等の帯電微粒子の少なくとも一方、のいずれかに対して空隙を設けて対向配置した回収体又は第１の回収体、あるいは除去部材で構成されており、この直流電位の規定を図３を用いて説明する。
【００７９】
画像情報形成体あるいは円筒状又はシート状部材の表面電位は画像情報形成体上のトナー等の帯電微粒子も含めた電位である。即ち、表面にトナー等の帯電微粒子が付着していないときは、画像情報形成体あるいは円筒状又はシート状部材の表面電荷による表面電位であり、表面にトナー等の帯電微粒子が付着しているときは、前記画像情報形成体あるいは円筒状又はシート状部材の表面電荷による表面電位とトナー等の帯電微粒子の持つ電荷による表面電位の和である。この表面電位は、通常画像情報形成体あるいは円筒状又はシート状部材が、負の光キャリアを多く移動させることができるため、表面は負の表面電荷を帯び、その電位は大きく負に偏っている。また、トナー等の帯電微粒子は、正あるいは負に帯電している状態で、前記画像情報形成体あるいは円筒状又はシート状部材の表面に付着して、全体としての電位は、負に偏っている。
【００８０】
一方、前記回収体又は第１の回収体、あるいは除去部材の直流電位は、飛翔共鳴が起こり、回収体又は第１の回収体、あるいは除去部材に飛翔するように画像形成装置の電源手段によって前記画像情報形成体あるいは円筒状又はシート状部材の表面電位を基準として、クリーニング電圧の直流バイアス電圧を印加して電位を規定する。トナー等の帯電微粒子の帯電極性が正ならば、前記画像情報形成体あるいは円筒状又はシート状部材の表面電位よりも小さい直流バイアス電圧を印加し、トナー等の帯電微粒子の帯電極性が負ならば、前記画像情報形成体あるいは円筒状又はシート状部材の表面電位よりも大きい直流バイアス電圧を印加する。これを数式で表すと数８のようになる。
【００８１】
【数８】

【００８２】
そして、画像形成装置の電源装置が印加するクリーニング電圧の直流バイアス電圧によって、この画像情報形成体のクリーニング領域での表面電位と回収体あるいは第１の回収体に印加するクリーニング電圧の直流バイアス電圧の電位差ΔＶ（数９）が、５０Ｖ以上かつ３５０Ｖ以下の範囲の時に、クリーニング性が向上する。
【００８３】
【数９】

【００８４】
次に後者のクリーニング電圧の交流バイアス電圧のピーク間電圧の関連は、交流バイアス電圧印加による振幅値と画像情報形成体あるいは円筒状又はシート状部材の表面電位との間の電位を規定するものである。この電位規定を図４を用いて説明する。
【００８５】
画像情報形成体あるいは円筒状又はシート状部材の表面電位は、前述してきたように通常表面は負の表面電荷を帯び、その電位は大きく負に偏っている。そして、本発明では回収体又は第１の回収体、あるいは除去部材には、直流バイアス電圧に交流バイアス電圧を重畳したクリーニング電圧を印加してクリーニングを行う。
【００８６】
図４において、画像形成装置の電源手段によって印加されるクリーニング電圧の交流バイアス電圧の波形は、正弦波、矩形波などであり、クリーニング電圧の印加波形そのもののピーク間電圧から得られる片振幅値Ｖ_{H A} は、
【００８７】
【数１０】

【００８８】
で、数１０から得られる片振幅値の小さい方の値が特に意味をもつ。しかし、この片振幅値は、クリーニング電圧の直流バイアス電圧Ｖ_{D C} が基準であり、この値だけでは、クリーニング性を考慮することはできず、画像情報形成体あるいは円筒状又はシート状部材の表面電位が関係する。
【００８９】
実際にクリーニングに寄与するのは、直流バイアス電圧に交流バイアス電圧を重畳した振動電圧等のクリーニング電圧による電位と画像情報形成体あるいは円筒状又はシート状部材の表面電位との電位関係（クリーニング電位の関係）から求められ、画像情報形成体あるいは円筒状又はシート状部材の表面電位が基準になる。即ち、画像情報形成体あるいは円筒状又はシート状部材のクリーニング領域での表面電位を基準とした回収体又は第１の回収体、あるいは除去部材に印加するクリーニング電圧による電位であり、その片振幅値Ｖは、
【００９０】
【数１１】

【００９１】
で、数１１から得られる片振幅値の小さい方の値が衝突雪崩モデルにおける逆飛翔電位であり、大きい方の値が衝突雪崩モデルにおける飛翔電位で、クリーニング性に関係し、この両方の片振幅値が飛翔閾値電圧以上であることが必要である。またこれは、衝突雪崩モデルのトナー等の帯電微粒子の飛翔機構で、回収体又は第１の回収体、あるいは除去部材への飛翔だけでなく、トナー等の帯電微粒子の逆飛翔が生じてトナー等の帯電微粒子の叩き出し効果が重要な意味を持つ。当然ながら、クリーニング電圧印加中に画像情報形成体のクリーニング領域で放電が生じないように、空隙に印加したクリーニング電圧と画像情報形成体あるいは円筒状又はシート状部材の表面電位との電位差、即ちクリーニング電位の片振幅値が、この空隙の空隙放電開始電圧以下である必要がある。
【００９２】
本発明の第４、第６、第７及び第８の発明には、画像形成装置のクリーニング手段が、画像情報形成体の表面からトナーを除去する第１のクリーニング手段と、第１のクリーニング手段の画像形成プロセスの下流側に画像情報形成体の表面から主としてトナー以外の付着物を除去する第２のクリーニング手段を有している。第１のクリーニング手段においては、前述してきたクリーニング電圧を第１の回収体に印加して、トナー等の帯電微粒子を除去する。その後、第２のクリーニング手段が画像情報形成体に接触して、画像情報形成体上に残留した残留物を除去する。
【００９３】
本発明の第６の発明では、第４及び第５の発明において、第１のクリーニング手段によって分離除去されたトナーを画像形成装置機外に廃棄しないで、全部もしくは一部を現像手段に搬送する回収搬送手段を設けている。この回収搬送手段は、第１のクリーニング手段の第１の回収体によって画像情報形成体から除去したトナーを、搬送パイプ中の搬送オーガやコイルスプリングが回転することによって回収されたトナーを順次搬送し、該トナーを現像手段のホッパなどに戻して、トナーをリサイクルする。本発明によれば、通常現像特性が悪化しなければ、現像手段に直接戻してもよし、場合によっては、搬送途中や現像手段に戻したときに、現像特性を改善する処理を施してもよい。
【００９４】
本発明の第７の発明では、画像形成装置の現像手段が、磁性もしくは非磁性の１成分非接触現像手段であり、クリーニング手段のみならず現像手段についても、非接触機構を用いることで、従来のブラシ現像法のような接触現像による画像情報形成体表面に損傷やフィルミングの発生が更に軽減される。
【００９５】
本発明の第８の発明では、画像形成装置の転写手段が、スコロトロン転写手段であり、スコロトロン転写手段による転写工程によって、転写用紙などの転写材上へのトナーの転写を確保したうえで、画像情報形成体や画像情報形成体上に残留したトナー等の帯電微粒子へのチャージの影響を低減する。これにより、クリーニング手段でのクリーニング性へのチャージの影響を少なくすることが可能で、常に一定のクリーニング性を保つことができる。
【００９６】
【実施例】
以下、本発明に係る画像形成装置の実施例について説明する。
【００９７】
（実施例１）
図１は、本発明に係る画像形成装置の第１の実施例の概略構成図である。本実施例の画像情報形成体である感光ドラム１０は、円筒形状のアルミニウム製のドラム基体と、該ドラム基体の外周表面に形成された有機光導電体層（ＯＰＣ層）を有する直径５０ｍｍ、長さ３１３ｍｍのもので、所定の周速度（プロセス・スピード）、例えば１７５ｍｍ／ｓで、時計方向（Ａ方向）に回転している。ここで、画像情報形成体１０としては、ドラム基体に限定されるものではなく、中空もしくは中実の円筒状あるいはシート状としてもよく、回転方向もＡ方向に限定されるものでもない。また、材質はアルミニウムに限定されるものでもなく、更にＯＰＣ層の上層に保護層や該ＯＰＣ層とドラム基体の間に下層を設けてもよい。
【００９８】
このＡ方向に回転する感光ドラム１０の表面は、図示しない帯電手段である帯電器によって現像工程での帯電微粒子であるトナーとは逆極性に帯電され、図示しない露光手段によって画像情報に応じた露光を受けて、感光ドラム１０の外周表面に静電潜像を形成し、図示しない現像手段である現像器によってトナーを現像して可視化後、図示しない転写手段である転写器によって転写材である転写用紙の表面に転写させる。この転写器を通過した後の感光ドラム１０の表面には、前記感光ドラム上に残留した残留物であるトナー等の帯電微粒子である未転写のトナー（残留トナー）７、紙粉、タルクなどが付着している。
【００９９】
クリーニング手段であるクリーニング装置１は、感光ドラム１０表面もしくは感光ドラム１０上の残留トナー７の少なくとも一方に対して空隙を設けて対向配置した回収体であるクリーニングローラ２、前記クリーニングローラに感光ドラム１０との間の前記空隙にクリーニングの用に供するバイアス電圧としてクリーニング電圧を印加する電源手段である電源装置３、及び該クリーニングローラによって回収したトナーをクリーニングローラ２の表面から掻き落とすウレタンゴム等のブレード４を有している。クリーニングローラ２は、その回転軸が感光ドラム１０の回転軸に平行になるようにして微小な空隙ｄを設けて反時計方向（Ｂ方向）に回転する。
【０１００】
クリーニングローラ２は、アルミニウム、銅、鉄などの金属材料及びそれらの合金材料、導電性を有するカーボン等の粒子やフィラー等（以下、導電性粒子と呼ぶ）やカーボンファイバ等の繊維（以下、導電性繊維と呼ぶ）等の導電性を有する材料をウレタンやシリコーン等の高分子材料に分散含有した導電性もしくは半導電性材料、即ち非絶縁性材料で構成される。これらは、導電性を有していればよいので、前記のカーボンを分散含有したウレタンゴムやシリコーンゴムなどの導電性ゴムやプラスチック材料、エンジニアリングプラスチックにカーボンファイバを適度に分散させたような高分子材料などであり、その他に導電性発泡ウレタン、導電性セラミック、導電性を有する多孔質材料、傾斜機能性材料なども用いることができる。
【０１０１】
クリーニングローラ２を導電性の有する材料、即ち非絶縁性材料で構成することにより、強度及び耐摩耗性に優れた金属材料やそれらの合金材料を用いることができ、非絶縁性を有するために任意のバイアス電圧を印加することができる。また、クリーニングローラ２を導電性を有するカーボン等の粒子やフィラー等の導電性粒子やカーボンファイバ等の導電性繊維などの導電性を有する材料を含有した導電性もしくは半導電性高分子材料で構成することにより、強度を維持しつつ金属材料などよりも軽量なクリーニングローラとすることができる。また更には、クリーニングローラ２の表面に導電性もしくは半導電性高分子材料を被覆した多層構造とすることもできる。
【０１０２】
本実施例のクリーニングローラ２を直径１２ｍｍ、長さ２５２ｍｍのアルミニウム製の中空の円筒状金属ローラとし、表面は平滑で、感光ドラム１０との空隙ｄを２００μｍとして対向配置する。この空隙ｄの値は加工精度や材料強度などの機械的制約及び空隙に印加する電圧や放電の防止などの電気的制約などにより任意に設定することができる。
【０１０３】
クリーニングローラ２には、電源装置３から例えばクリーニング電圧として直流バイアス電圧に交流バイアス電圧を重畳した振動電圧が印加される。このクリーニング電圧の直流バイアス電圧により感光ドラム１０の表面に残留している残留トナー７をクリーニングローラ２の表面にクーロン力で静電吸引する。クリーニングローラ２に静電吸引されて付着したトナーは、クリーニングローラ２の表面に接触するブレード４により掻き落とされ、図示しない回収ボトル等に回収される。
【０１０４】
感光ドラム１０の表面電位は前記感光ドラム上のトナー等の帯電微粒子も含めた電位で、表面にトナー等の帯電微粒子が付着していないときは、感光ドラム表面電荷による表面電位であり、表面にトナー等の帯電微粒子が付着しているときは、前記感光ドラムの表面電荷による表面電位とトナー等の帯電微粒子の持つ電荷による表面電位の和である。本実施例の感光ドラムは、負帯電特性を有しており、負の表面電荷を帯びて、表面電位は現像工程後ならば−５００Ｖ程度、コロトロン転写器を用いた転写工程後ならば−９００〜−１０００Ｖ程度まで、大きく負に偏っている。また、トナー等の帯電微粒子は、画像形成プロセスの各工程を経ることによる差はあるが正あるいは負に２０Ｖ〜２００Ｖ程度帯電している状態で、感光ドラム１０の表面に付着して、殆どの場合全体としての電位は、負に偏っている。
【０１０５】
このような状態の感光ドラム１０に対してクリーニング電圧を印加して、感光ドラム１０から残留トナー７を除去する場合、電源装置３によって印加するクリーニング電圧の直流バイアス電圧Ｖ_{D C} と前述した感光ドラム１０の表面電位Ｖ₀ との関係からクリーニング性に大きな差が見られる。この直流バイアス電圧と表面電位との大小関係によるクリーニング性を調べた結果の一例を図５に示す。図５では、残留トナー７の帯電極性が正（＋）のとき、（１）のＶ₀ ＞Ｖ_{D C} の場合にクリーニング性は良く、（３）のＶ₀ ＜Ｖ_{D C} の場合にクリーニング性は悪化する。また、残留トナー７の帯電極性が負（−）のとき、（１）のＶ₀ ＞Ｖ_{D C} の場合にクリーニング性は悪化し、（３）のＶ₀ ＜Ｖ_{D C} の場合にクリーニング性は良くなる。更に、（２）のＶ₀ ＝Ｖ_{D C} の場合には感光ドラム１０とクリーニングローラ２の間のクリーニング領域の微小な電位分布状態によって、極く少量がクリーニングされるときがある。
【０１０６】
次に本出願人は、感光ドラム１０に対してクリーニング電圧を印加して、感光ドラム１０から残留トナー７を除去する場合、電源装置３によって印加するクリーニング電圧の直流バイアス電圧Ｖ_{D C} と前述した感光ドラム１０の表面電位Ｖ₀ との電位差が、特定の範囲にあるときに残留トナー７の感光ドラム１０からクリーニングローラ２への飛翔が促進され、クリーニング性が良好となることを見いだした。このクリーニング電圧の直流バイアス電圧と感光ドラム１０の表面電位との電位差ΔＶとクリーニング性との関係の一例を図６に示す。この図６では、電位差ΔＶがおおむね５０Ｖから３５０Ｖであれば良好なクリーニング効率を示す。種々の条件で実験を行った結果、クリーニング電圧を印加する電源手段である電源装置３によって、クリーニング電圧の直流バイアス電圧Ｖ_{D C} と感光ドラム１０の表面電位Ｖ₀ との電位差ΔＶを、５０Ｖ以上かつ３５０Ｖ以下となるクリーニング電圧を印加すれば、良好なクリーニング性を示し、優れた画像形成装置が構成できる。
【０１０７】
なお、感光ドラム１０やクリーニングローラ２、ブレード４などの寸法、構造、材質、周速度等は上述のものに限らず、種々のものが考えられ、例えば感光ドラムは直径８０ｍｍ、長さ３５８ｍｍ、クリーニングローラは直径２０ｍｍ、長さ３１０ｍｍの場合においても、同様である。
【０１０８】
（実施例２）
図７は、本発明に係る画像形成装置の第２の実施例の概略構成図である。第１の実施例と同様の画像形成装置であり、感光ドラム１０やクリーニング手段であるクリーニング装置のクリーニングローラ２の構造、材質等主要構成も同様である。図７では、クリーニング電圧をクリーニングローラ２に印加する電源手段である電源装置３が、直流バイアス電圧を印加する直流電源回路１３と交流バイアス電圧を印加する交流電源回路１４を有しており、具体的に直流バイアス電圧に交流バイアス電圧を重畳した振動電圧を印加することを示している。例えば、振動電圧として、直流バイアス電圧を＋２００Ｖあるいは−２００Ｖとし、交流バイアス電圧を周波数３ｋＨｚ、ピーク間電圧２ｋＶｐ−ｐを印加する。交流バイアス電圧の周波数、ピーク間電圧、直流バイアス電圧の大きさは、前述のものに限らず、種々の値に設定して、印加することができる。
【０１０９】
本実施例の画像情報形成体である感光ドラム１０も、円筒形状のアルミニウム製のドラム基体と、該ドラム基体の外周表面に形成された有機光導電体層（ＯＰＣ層）を有する直径５０ｍｍ、長さ３１３ｍｍのもので、所定の周速度（プロセス・スピード）、例えば１７５ｍｍ／ｓで、時計方向（Ａ方向）に回転し、またクリーニングローラ２も直径１２ｍｍ、長さ２５２ｍｍのアルミニウム製の中空の円筒状金属ローラとし、表面は平滑で、感光ドラム１０との空隙ｄを２００μｍとして対向配置する。
【０１１０】
直流バイアス電圧に交流バイアス電圧を重畳した振動電圧をクリーニングローラ２に印加してクリーニングを行う場合、クリーニングに寄与するのは、画像情報形成体である感光ドラム１０のクリーニング領域での表面電位を基準とした回収体であるクリーニングローラ２に印加されるクリーニング電圧による電位（クリーニング電位）の片振幅値Ｖから求められる電位関係である。
【０１１１】
本出願人は、クリーニング電位の片振幅値が衝突雪崩モデルで表される飛翔機構におけるトナー７の飛翔電位及び逆飛翔電位それぞれが飛翔閾値電圧以上であり、かつクリーニング電圧印加中に感光ドラムのクリーニング領域では放電が生じないように空隙放電開始電圧以下であれば、良好なクリーニング性が得られることを見い出した。図８に前述したクリーニング電位の片振幅値とクリーニング性について調べた結果の一例を示す。図８に示すように、クリーニング性はクリーニング電位の片振幅値に対して、閾値を持っている。
【０１１２】
そして、種々の条件で実験を行った結果、クリーニング電圧を印加する電源手段である電源装置３によって、クリーニングローラ２にクリーニング電圧を印加し、感光ドラム１０のクリーニング領域での表面電位を基準としたクリーニング電圧によるクリーニング電位の片振幅値をおおむね５００Ｖ以上かつ空隙放電開始電圧以下となるようにすることで、良好なクリーニング性を示し、優れた画像形成装置が構成できる。
【０１１３】
なお、感光ドラム１０やクリーニングローラ２、ブレード４などの寸法、構造、材質、周速度等は上述のものに限らず、種々のものが考えられる。
【０１１４】
（実施例３）
図９は、本発明に係る画像形成装置の第３の実施例の概略構成図である。本実施例の画像情報形成体である感光ドラム１０は、円筒形状のアルミニウム製のドラム基体と、該ドラム基体の外周表面に形成された有機光導電体層（ＯＰＣ層）を有する外形５０ｍｍ、長さ３１３ｍｍのもので、所定の周速度（プロセス・スピード）、例えば１７５ｍｍ／ｓで、時計方向（Ａ方向）に回転している。ここで、感光ドラム１０の構造、材質等は、実施例１に述べたようにドラム基体に限定されるものではなく、中空もしくは中実の円筒状あるいはシート状としてもよく、回転方向もＡ方向に限定されるものでもない。
【０１１５】
本実施例に示す画像形成装置の画像形成プロセスは、ほぼ実施例１に述べたものと同様であるが、画像形成装置のクリーニング手段は、感光ドラムの表面から主としてトナーを除去する第１のクリーニング手段の第１の回収体である第１のクリーニングローラ２と、第１のクリーニングローラ２の画像形成プロセスの下流側に感光ドラム１０の表面から主としてトナー以外の付着物を除去する第２のクリーニング手段の第２の回収体である第２のクリーニングローラ５を有している。第１のクリーニングローラ２は、実施例１で述べたものと同様で、感光ドラム表面もしくは感光ドラム上のトナー等の帯電微粒子の少なくとも一方に、空隙ｄを設けて対向配置している。そして、実施例１と同様に前記第１のクリーニングローラに感光ドラム１０との間の前記空隙にクリーニングの用に供するバイアス電圧としてクリーニング電圧を印加する電源手段である電源装置３、及び該第１のクリーニングローラに回収したトナーを第１のクリーニングローラ２の表面から掻き落とす第１のブレード４を有している。
【０１１６】
本実施例のクリーニングローラ２を直径１２ｍｍ、長さ２５２ｍｍのアルミニウム製の中空の円筒状金属ローラとし、表面は平滑で、感光ドラム１０との空隙ｄを２００μｍとして対向配置する。この空隙ｄの値は加工精度や材料強度などの機械的制約及び空隙に印加する電圧や放電の防止などの電気的制約などにより任意に設定することができる。その他、トナーの除去機構等は、実施例１と同様である。
【０１１７】
本実施例でも電源装置３によるクリーニング電圧の印加は、実施例１と同様で、直流バイアス電圧と表面電位との大小関係によってクリーニング性は異なる。
【０１１８】
例えば、残留トナー７の帯電極性が正（＋）のとき、図５と同様に（１）のＶ₀ ＞Ｖ_{D C} の場合にクリーニング性は良く、（３）のＶ₀ ＜Ｖ_{D C} の場合にクリーニング性は悪化する。また、残留トナー７の帯電極性が負（−）のとき、（１）のＶ₀ ＞Ｖ_{D C} の場合にクリーニング性は悪化し、（３）のＶ₀ ＜Ｖ_{D C} の場合にクリーニング性は良くなる。また、電源装置３によって印加するクリーニング電圧の直流バイアス電圧Ｖ_{D C} と前述した感光ドラム１０の表面電位Ｖ₀ との電位差が、特定の範囲にあるときに残留トナー７の感光ドラム１０からクリーニングローラ２への飛翔が促進され、優れたクリーニング性を示す。このクリーニング電圧の直流バイアス電圧と感光ドラム１０の表面電位との電位差ΔＶは、例えば５０Ｖ以上かつ３５０Ｖ以下となるクリーニング電圧を印加すれば、良好なクリーニング性を示し、優れた画像形成装置が構成できる。また更に、クリーニング電圧を印加する電源手段である電源装置３によって、クリーニングローラ２にクリーニング電圧を印加し、感光ドラム１０のクリーニング領域での表面電位を基準としたクリーニング電圧によるクリーニング電位の片振幅値をおおむね５００Ｖ以上かつ空隙放電開始電圧以下となるようにすることで、良好なクリーニング性を示し、優れた画像形成装置が構成できる。
【０１１９】
また、第２のクリーニング手段は、第２の回収体である第２のクリーニングローラ５及び第２のクリーニングローラ５の表面から主としてトナー以外の付着物を掻き落とす第２のブレード６を有している。第２のクリーニングローラ５は、その回転軸が感光ドラム１０の回転軸に平行になるようにしてソフトに接触して、感光ドラム１０の表面を圧接摺動し時計方向（Ｃ方向）に回転する。第２のクリーニングローラ５は、絶縁性弾性材料で構成されており、例えば絶縁性を有するソリッドゴム、多孔質発泡スポンジゴムなどの高分子有機材料からなる円筒状ローラである。該第２のクリーニングローラ５は、絶縁性を有する繊維等の高分子有機材料からなるブラシ状ローラとすることもできる。また、前記第２のクリーニングローラ５は、絶縁性弾性材料以外に非絶縁性材料である導電性あるいは半導電性弾性材料とすることもできる。
【０１２０】
第２のクリーニングローラ５を絶縁性材料により構成することで、成型性及び生産性に優れたウレタン、シリコンなどで形成されるソリッドゴムや多孔質発泡スポンジゴム等の高分子有機材料を用いることができる。また、第２のクリーニングローラ５を非絶縁性材料により構成することで、第２のクリーニングローラ５にバイアス電圧を印加して、バイアスを印加しない場合の付着物の除去作用に加えて、更に静電力による除去作用を大きく付与することもできる。
【０１２１】
本実施例の図９に示す画像形成装置では、第２のクリーニングローラ５は、直径１２ｍｍ、長さ２５２ｍｍ、アスカーＣ硬度５０゜の独立発泡ウレタン製の中実の円筒状絶縁性弾性ローラであり、感光ドラム１０の表面に押圧２００ｇｆ／ｃｍで圧接配置する。この押圧は、感光ドラム１０の構造、表面材質、表面の平滑性およびプロセス速度などに基づいて、感光ドラムの表面にダメージを与えない程度にソフトに圧接するよう任意に設定することができる。
【０１２２】
前述してきた第１のクリーニング手段及び第２のクリーニング手段によって、感光ドラム１０の表面に残留する残留物を除去する。先ず、第１のクリーニング手段によって転写工程後の感光ドラム１０に対して、第１のクリーニングローラ２にクリーニング電圧である直流バイアス電圧に交流バイアス電圧を重畳した振動電圧を印加して、該感光ドラムの表面に残留している残留トナー７を除去し、続いて下流側にある第２のクリーニングローラ５を該感光ドラムに圧接摺動することにより、紙粉及びタルクなどのトナー以外の付着物８を除去する。
【０１２３】
第１のクリーニングローラ２は、実施例１と同様の機構で主として残留トナー７を除去する。第１のクリーニングローラ２により除去された残留トナー７は、該第１のクリーニングローラの表面に接触する第１のブレード４により該第１のクリーニングローラの表面から掻き落とされる。
【０１２４】
第２のクリーニングローラ５は、感光ドラム１０の表面に柔軟性をもって圧接摺動し、主としてトナー以外の付着物８を機械的剪断力により該感光ドラムの表面から除去する。第２のクリーニングローラ５により除去された付着物８は、該第２のクリーニングローラ５の表面に接触する第２のブレード６により第２のクリーニングローラ５の表面から掻き落とされ、図示しない回収ボトルに回収され、残留トナー７とは分離回収される。
【０１２５】
図９に示した本実施例の構成を少し変更して、第２のクリーニングローラ５を非絶縁性材料である導電性あるいは半導電性弾性材料とした画像形成装置の一実施例を図１０に示す。同図では、第２のクリーニングローラ５は、直径１２ｍｍ、長さ２５２ｍｍのカーボンなどの導電性を有する材料を含有したソリッドゴムや多孔質発泡スポンジゴムなどの高分子有機材料であり、例えば、体積抵抗値が１×１０⁷ 〜１×１０⁹ Ω・ｃｍの発泡ウレタンスポンジゴムや発泡シリコンスポンジゴムである。また、同図では、第２のクリーニングローラ５をスポンジとしたが、ソリッドゴムとしてもよい。第２のクリーニングローラ５の体積抵抗値が、前記の範囲より外れると望ましいクリーニング性が得られない。例えば、体積抵抗値が１×１０⁷ Ω・ｃｍ未満の場合、渦電流によって付着物８が表面に被膜形成が生じ、逆に１×１０⁹ Ω・ｃｍより大きい場合、材料自身の抵抗値のばらつきが大きくなり、クリーニング性の低下を招くことになる。第２のクリーニングローラ５には外部に直流バイアス電圧を印加する第２の電源装置が接続されている。
【０１２６】
第１のクリーニングローラ２の感光ドラム１０に対する周速比は、種々検討を行った結果、５０％〜５００％の範囲で感光ドラム１０の回転方向と逆方向（Ｂ方向）に回転させることにより、回収した残留トナー７が第１のクリーニングローラ２から飛散することなく回収、除去できる。前記周速比の範囲は、好ましくは１００％〜３００％において、感光ドラム１０の表面からの残留トナー７のクリーニング性がより高まり、極めて良好なクリーニング性を得ることができる。
【０１２７】
また、第２のクリーニングローラ５の感光ドラム１０に対する周速比は、種々検討を行った結果、５０％〜５００％の範囲で感光ドラム１０の回転方向と逆方向（Ｃ方向）に回転させることにより、トナー以外の付着物８を除去することができる。詳細には、周速比が１００％以上でクリーニング性が高まり、２００％を越えると第２のクリーニングローラ５と感光ドラム１０の表面との機械的剪断力が大きくなるので、前記周速比の範囲は、好ましくは１００％〜２００％の範囲で第２のクリーニングローラ５を回転させることにより、良好なクリーニング性を得ることができる。
【０１２８】
本実施例における電源手段である電源装置３は、クリーニング電圧を印加するために、直流バイアス電圧を印加する直流電源回路１３及び交流バイアス電圧を印加する交流電源回路１４を有している。クリーニング電圧は、例えば、空隙ｄを２００μｍとし、感光ドラム１０の表面電位Ｖ₀ を−５００Ｖとした場合、直流バイアス電圧Ｖ_{D C} を−３００Ｖ、交流バイアス電圧のピーク間電圧Ｖ_{A C} を２ｋＶｐ−ｐ，その周波数を３ｋＨｚとする。このようにすることで、残留トナー７の帯電極性が正極性ならば、Ｖ₀ ＞Ｖ_{D C} となるようにバイアス電圧を印加でき、残留トナー７の除去が容易に行え、感光ドラム１０のクリーニング領域での表面電位と前記第１のクリーニングローラに印加するクリーニング電圧の直流バイアス電圧との電位差ΔＶが、５０Ｖ以上かつ３５０Ｖ以下である。また、交流電源装置の交流バイアス電圧として、２ｋＶｐ−ｐを与えて残留トナー７に静電的な振動力を加えて、そのトナーの運動によって残留トナー７に機械的な力を与えて、感光ドラム１０の表面から除去する。交流バイアス電圧は、残留トナー７に静電的な振動力を与えればよく、その周波数や振幅値も任意であり、印加波形としては、正弦波に限らず矩形波、三角波、矩形波、矩形波の微分波あるいは矩形波の積分波などが考えられ、直流バイアス電圧を境に振動するに印加波形であれば本実施例の様な場合のクリーニング電圧として適用でき、例えば、周波数が１２ｋＨｚの矩形波を印加してもよい。クリーニング電圧印加条件としては、上記の場合に限らず、周波数５００〜１５ｋＨｚ、ピーク間電圧５００Ｖ〜５ｋＶｐ−ｐ、好ましくは、周波数１ｋＨｚ〜１５ｋＨｚで、かつピーク間電圧は１〜−４ｋＶｐ−ｐであり、直流バイアス電圧の絶対値は、５０Ｖ〜４００Ｖ、好ましくは、５０Ｖ〜３５０Ｖである。
【０１２９】
また、第２のクリーニングローラ５は非絶縁性材料で構成されているので、図１０に示すように第２の電源装置によって数１０Ｖ〜数１００Ｖ程度の直流バイアス電圧を印加したり、接地したりしてもよい。
【０１３０】
なお、感光ドラム１０や第１のクリーニングローラ２及び第２のクリーニングローラ５、第１のブレード４及び第２のブレード６などの寸法、構造、材質、周速度等は上述のものに限らず、種々のものが考えられ、例えば感光ドラムは直径８０ｍｍ、長さ３５８ｍｍ、クリーニングローラは直径２０ｍｍ、長さ３１０ｍｍの場合においても、同様である。
【０１３１】
（実施例４）
図１１は、本発明に係る画像形成装置の第４の実施例の概略構成図である。基本的な構成は第３の実施例と同様の画像形成装置である。本実施例の画像情報形成体である感光ドラム１０は、円筒形状のアルミニウム製のドラム基体と、該ドラム基体の外周表面に形成された有機光導電体層（ＯＰＣ層）を有する外形５０ｍｍ、長さ３１０ｍｍのもので、所定の周速度（プロセス・スピード）、例えば１７５ｍｍ／ｓで、時計方向（Ａ方向）に回転している。ここで、感光ドラム１０の構造、材質等は、実施例１に述べたようにドラム基体に限定されるものではなく、中空もしくは中実の円筒状あるいはシート状としてもよく、回転方向もＡ方向に限定されるものでもない。
【０１３２】
本実施例に示す画像形成装置の画像形成プロセスは、実施例３に述べたものと同様であるが、画像形成装置のクリーニング手段は、感光ドラムの表面から主としてトナーを除去する第１のクリーニング手段の第１の回収体である第１のクリーニングローラ２と、第１のクリーニングローラ２の画像形成プロセスの下流側に感光ドラム１０の表面から主としてトナー以外の付着物を除去する第２のクリーニング手段の第２の回収体である第２のクリーニングローラ５を有している。第１のクリーニングローラ２は、実施例１で述べたものと同様で、感光ドラム表面もしくは感光ドラム上のトナー等の帯電微粒子の少なくとも一方に、空隙ｄを設けて対向配置している。そして、実施例１と同様に前記第１のクリーニングローラ２に感光ドラム１０との間の前記空隙にクリーニングの用に供するバイアス電圧としてクリーニング電圧を印加する電源手段である電源装置３、及び該第１のクリーニングローラ２に回収したトナーを第１のクリーニングローラ２の表面から掻き落とす第１のブレード４を有している。
【０１３３】
第２のクリーニング手段は、第２の回収体である第２のクリーニングローラ５及び第２のクリーニングローラ５の表面から主としてトナー以外の付着物を掻き落とす第２のブレード６を有している。第２のクリーニングローラ５は、その回転軸が感光ドラム１０の回転軸に平行になるようにしてソフトに接触して、感光ドラム１０の表面を圧接摺動し時計方向（Ｃ方向）に回転する。
【０１３４】
本実施例に示す画像形成装置は、上記構成に加えて、画像形成装置のクリーニング手段、即ち第１のクリーニングローラ２及び第２のクリーニングローラ５によって分離除去されたトナー及びトナー以外の残留物である紙粉タルク等を回収搬送する回収搬送手段を設けている。回収搬送手段は、第１及び第２のクリーニング手段によって分離回収されたトナーを回収して搬送するための手段であるコイルスプリング２３、搬送パイプ２２を有しており、これによって分離回収を行う。
【０１３５】
本実施例の画像形成装置の回収搬送手段は、感光ドラム１０上に残留したトナー７を、始めに第１のクリーニングローラ２によって非接触で除去し振動電圧を印加して静電的に回収し、次いで第２のクリーニングローラ５によって、紙粉・タルク等の付着物８を感光ドラムに接触して回収する。先ず、第１のクリーニングローラ２によって回収された残留トナー７は、第１のブレード４によって、第１のクリーニングローラ２の表面から掻き落とされる。
【０１３６】
回収搬送手段は、搬送パイプ２２の中にコイルスプリング２３を入れたもので、コイルスプリング２３がねじれることで推力が働き、トナー等の物質を搬送する。この回収搬送手段であるコイルスプリング２３や搬送パイプ２２は、第１のクリーニングローラ２で回収された残留トナー７を第１のブレード４で掻き落とし、掻き落とされた残留トナーが搬送パイプ２２の中に入り込み、コイルスプリング２３によって搬送パイプ２２内を搬送され、現像手段のホッパに戻され、現像プロセスを実行するために再利用される。従来まで紙粉やタルクといったトナー以外の残留物と交じった状態で回収ボトルに回収されて、機外に排出されていたが、このように分離回収を行い、回収搬送手段を設けてリサイクル機構を構成することで、第１のクリーニングローラ２によって残留トナー７の殆どを回収し、第２のクリーニングローラ５で紙粉やタルクを残留トナー７とは別に回収して、機外に排出される。
【０１３７】
また、第１のクリーニングローラ２によって分離回収された残留トナー７は、そのまま現像手段のホッパ内に供給されるが、リサイクル機構を構成する搬送パイプ２２やコイルスプリング２３以外に、途中の搬送経路に回収したトナー（以下、リサイクルトナーと呼ぶ）の特性（特に、現像特性）を途中の搬送経路において適切に処理するトナー再生処理手段２５を設けることがある。このトナー再生処理手段２５で、リサイクルトナーの帯電特性等を処理して、現像手段での現像工程が所望の特性を発揮するようにする（図１２）。これにより、転写後に残留した残留トナー７を効率的に除去でき、再利用することで、トナーの無駄な消費を押さえて、効率的な画像形成プロセスを実行することができる。
【０１３８】
本実施例におけるクリーニング電圧の印加についても、直流バイアス電圧や交流バイアス電圧の大きさ、感光ドラムの表面電位との電位差、片振幅値等は前述してきた実施例と同様のことがいえる。
【０１３９】
なお、感光ドラム１０や第１のクリーニングローラ２及び第２のクリーニングローラ５、第１のブレード４及び第２のブレード６などの寸法、構造、材質、周速度等は上述のものに限らず、種々のものが考えられ、例えば感光ドラムは直径８０ｍｍ、長さ３５８ｍｍ、クリーニングローラは直径２０ｍｍ、長さ３１０ｍｍの場合においても、同様である。
【０１４０】
（実施例５）
図１３に示す画像形成装置は、実施例３に示す画像形成装置の現像手段を、磁性もしくは非磁性の１成分非接触現像手段にしたものである。
【０１４１】
実施例３に示した画像形成装置の現像工程以外の画像形成プロセスは、実施例３と同様であるが、従来の２成分接触現像手段は現像工程の磁性もしくは非磁性の１成分非接触現像手段と比べても現像性は劣らず、逆に非接触であるので、感光ドラム１０へのダメージを低減することができる。
【０１４２】
図１３では非磁性の非接触現像手段を用いたものを示す。同図では、現像工程時のトナー担持体である現像ローラ２４には、現像バイアスとして−２００Ｖを印加する。このとき、現像ローラ２４は、感光ドラムに対して約１５０μｍの現像ギャップを設けて配設してある。
【０１４３】
また、転写工程後に感光ドラム１０の上に残留する残留トナー７や紙粉やタルクといったトナー以外の付着物８を除去するクリーニング手段は、第１のクリーニング手段である第１のクリーニングローラ２は、感光ドラム１０に対して非接触であり、おおむね２００μｍの空隙を設けて、更に第１のクリーニングローラ２が非接触であり、従来のようにクリーニングブレードによるキズがは少なくなる傾向にある。また、第２のクリーニングローラ５は、従来のクリーニングブレードを用いた場合よりもソフトタッチで接触しており、感光ドラム１０へのダメージを低減できる。また、回収搬送手段を設けて、残留トナー７のリサイクル機構を付加してもよい。
【０１４４】
（実施例６）
図１４に示す画像形成装置は、実施例３に示す画像形成装置の転写手段を、スコロトロン転写手段にしたものである。
【０１４５】
実施例３に示した画像形成装置の転写工程以外の画像形成プロセスは、実施例３と同様である。従来の画像形成装置の転写手段には、転写材である転写用紙に９７にトナー像を転写するために、コロトロン転写手段を用いて転写用紙９７の裏面から十分な電荷を付与して転写を行っていたが、特に高湿時に十分な転写性を確保するために、マージンを多く取ってコロナ放電電流を流している。そして、このトナー像を転写用紙９７に転写する際、感光ドラム１０の上に残留する残留トナー７に余分な電荷が付与され、クリーニング性に影響を与える。そこで、本実施例に本発明を用いることで、画像形成装置の転写手段にスコロトロン転写手段３０を用い、残留トナー７への余分な電荷付与が生じないように、かつトナー像の転写用紙９７への転写性を損なわないように画像形成プロセスを実行することができる画像形成装置を構成することが可能である。
【０１４６】
同図において、現像手段は、１成分あるいは２成分の接触／非接触いづれの現像方法でもよい。転写手段であるスコロトロン転写手段３０は、放電ワイヤ３１に数ｋＶの直流電圧や直流電圧に交流電圧を重畳した振動電圧を印加して、放電ワイヤ３１近傍で放電させて、電荷を発生させる。このとき、スコロトロン転写手段では、放電ワイヤ３１と感光ドラム１０との間、あるいは放電ワイヤ３１と転写用紙９７との間にグリッド３２を設けて、感光ドラム１０への電荷の照射量を制御し、転写性を確保しつつ、残留トナー７への影響を少なくすることができる。通常、グリッド３２には、バイアス電圧を印加し、感光ドラム１０の表面電位や転写用紙９７の裏面の電位を制御することができる。即ち、グリッド３２と感光ドラム１０の表面や転写用紙９７の裏面との電位差が大きいと多く電荷が照射され、逆に電位差が小さいと少ない電荷の照射になる。従って、グリッド３２によって放電ワイヤ３１からグリッド３２を通過して、感光ドラム１０や転写用紙９７に照射する電荷量をコントロールすることが可能で、最終的にはグリッド３２へのバイアス電圧と感光ドラム１０の表面電位や転写用紙の裏面の電位とが等しくなるとグリッド３２を通過する電荷はなくなる。
【０１４７】
本実施例におけるクリーニング電圧の印加についても、直流バイアス電圧や交流バイアス電圧の大きさ、感光ドラムの表面電位との電位差、片振幅値等は前述してきた実施例と同様のことがいえる。
【０１４８】
なお、感光ドラム１０や第１のクリーニングローラ２及び第２のクリーニングローラ５、第１のブレード４及び第２のブレード６などの寸法、構造、材質、周速度等は上述のものに限らず、種々のものが考えられ、例えば感光ドラムは直径８０ｍｍ、長さ３５８ｍｍ、クリーニングローラは直径２０ｍｍ、長さ３１０ｍｍの場合においても、同様である。更に、回収搬送手段を設けて、残留トナー７のリサイクル機構を付加してもよい。
【０１４９】
（実施例７）
図１５には、電子写真方式により画像情報形成体表面に電子潜像を形成し、トナー等の帯電微粒子により顕像化し、転写材上に帯電微粒子を転写し、画像情報形成体上に残留した残留物をクリーニングし、転写材上の帯電微粒子を定着する一連の画像形成プロセスを実行する画像形成装置の一実施例を示す。
【０１５０】
本実施例では、トナー等の帯電微粒子により顕像化する現像手段が、磁性もしくは非磁性の１成分非接触現像手段であり、転写材上に帯電微粒子を転写する転写手段が、ローラ転写手段３４である。ローラ転写手段３４には、外部から転写用のバイアス電圧を印加する。
【０１５１】
そして、前記画像情報形成体の表面から電気的にトナーを除去する第１のクリーニング手段と、第１のクリーニング手段の画像形成プロセスの下流側に、前記画像情報形成体表面に残留するトナー等の帯電微粒子、紙粉やタルクなどのトナー以外の付着物などの残留物を前記画像情報形成体から除去する第２のクリーニング手段を有するクリーニング手段であり、前記第１のクリーニング手段によって前記画像情報形成体から除去されたトナー等の帯電微粒子を回収して、現像手段に搬送する回収搬送手段を設ける。
【０１５２】
また、そして画像情報形成体の表面をクリーニングする前記第１のクリーニング手段や前記ローラ転写方式のローラ転写手段３４によって前記画像情報形成体表面に残留するトナー等の帯電微粒子、紙粉やタルクなどのトナー以外の付着物などの残留物のうちトナー等の帯電微粒子を前記第１のクリーニング手段でクリーニングする際に、前記第１のクリーニング手段は、画像情報形成体表面もしくは画像情報形成体上のトナー等の帯電微粒子の少なくとも一方に、空隙を設けて対向配置した第１の回収体、前記第１の回収体に画像情報形成体との間の前記空隙にクリーニング電圧を印加する電源手段を有している。
【０１５３】
そして、前記電源手段は、前記画像情報形成体のクリーニング領域での表面電位をＶ₀、前記第１の回収体に印加するクリーニング電圧の直流バイアス電圧をＶ_DC、前記空隙の空隙放電開始電圧をＶ_Bとすると、前記帯電微粒子の帯電極性が正極性ならば、Ｖ₀＞Ｖ_DCとなるようにクリーニング電圧を印加し、前記帯電微粒子の帯電極性が負極性ならば、Ｖ₀＜Ｖ_DCとなるようにクリーニング電圧を印加するものであり、かつ前記画像情報形成体のクリーニング領域での表面電位と前記回収体に印加するクリーニング電圧の直流バイアス電圧との電位差ΔＶが、５０Ｖ以上かつ３５０Ｖ以下となるようにクリーニング電圧を印加するものであり、更に、前記画像情報形成体のクリーニング領域での表面電位Ｖ₀を基準とした前記第１の回収体に印加するクリーニング電圧による電位の片振幅電圧値Ｖが、５００Ｖ以上かつＶ_B以下となるようにクリーニング電圧を前記空隙に印加するものである。
【０１５４】
【発明の効果】
本発明によれば、画像情報形成体表面の帯電微粒子であるトナーを、非接触で効率よく除去でき、画像品質の低下がなく、安定したクリーニング性能を維持できるクリーニング手段を備えた画像形成装置を構成でき、クリーニング不良や放電を防止でき、バイアス印加条件を適正化することで、画像情報形成体上の帯電状態や残留物の付着状態の影響を受けにくくすることができる。
【０１５５】
また、画像情報形成体表面の帯電微粒子であるトナーや紙粉及びタルク等の残留物を、その種類ごとに応じて除去できるようにし、画像情報形成体表面に損傷やトナーやタルクなどの付着物のフィルミングを防止し、残留した紙粉やタルクなどのトナー以外の付着物も確実に除去でき、画像情報形成体の長寿命化及び高速化を実現できるクリーニング手段を備えた画像形成装置を構成できる。
【０１５６】
更にまた、トナーや紙粉等の帯電微粒子を分離回収して、トナーリサイクル機構を構成する上で問題となる、回収トナーの再生が容易で、現像手段での撹拌による摩擦帯電、トナー層形成及び現像特性に悪影響を及ぼさないクリーニング手段及び回収搬送手段が構成できる。
【０１５７】
そして、付加的な効果として、電子写真方式による画像形成プロセスで用いられるトナー等の帯電微粒子が、従来の粉砕法等で作製された表面形状の粗いものや、重合法等で作製された表面形状の平滑なものといったクリーニングブレード等の接触もしくは当接させるクリーニング法でクリーニングしにくいトナー等の帯電微粒子も除去できるので、トナー等の帯電微粒子の形状、材質、特性等に影響されにくく、優れたクリーニング性をもつクリーニング手段を備えた画像形成装置を構成することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施例に係る画像形成装置の概略構成図である。
【図２】クリーニング電圧の交流バイアス電圧の周波数に対するクリーニング効率を示す図である。
【図３】画像情報形成体の表面電位と回収体に印加するクリーニング電圧との関係を説明する図である。
【図４】画像情報形成体の表面電位と回収体に印加するクリーニング電圧の交流電位と関係を説明する図である。
【図５】本発明のクリーニング性の判定結果を示す図である。
【図６】クリーニング電圧の直流バイアス電圧と感光ドラムの表面電位との電位差とクリーニング効率との関係を示す図である。
【図７】本発明の第２の実施例に係る画像形成装置の概略構成図である。
【図８】クリーニング電圧として印加する交流バイアス電圧の片振幅とクリーニング効率との関係を示す図である。
【図９】本発明の第３の実施例に係る画像形成装置の概略構成図である。
【図１０】本発明の第３の実施例に係る異なる構成をとった場合の画像形成装置の概略構成図である。
【図１１】本発明の第４の実施例に係る画像形成装置の概略構成図である。
【図１２】本発明の第４の実施例にトナー再生処理手段を設けた画像形成装置の概略構成図である。
【図１３】本発明の第５の実施例に係る画像形成装置の概略構成図である。
【図１４】本発明の第６の実施例に係る画像形成装置の概略構成図である。
【図１５】本発明の第７の実施例に係る画像形成装置の概略構成図である。
【図１６】従来の画像形成装置の概略構成図である。
【符号の説明】
ｄ 空隙
１ クリーニング装置
２ クリーニングローラあるいは第１のクリーニングローラ
３ 電源装置
４ ブレードあるいは第１のブレード
５ 第２のクリーニングローラ
６ 第２のブレード
７ 残留トナー
８ 紙粉、タルクなどのトナー以外の付着物
１０ 感光ドラム
１１ 第２の電源装置
１３ 直流電源回路
１４ 交流電源回路
２１ 現像手段
２２ 搬送パイプ
２３ コイルスプリング
２４ 現像ローラ
２５ トナー再生処理手段
３０ スコロトロン転写手段
３１ 放電ワイヤ
３２ グリッド
３３ シールドケース
３４ ローラ転写手段
８１ トナー
８２ 残留トナー
８３ 付着物
９０ 感光ドラム
９１ 帯電手段
９２ 露光手段
９３ 現像手段
９４ 転写手段
９５ 除電手段
９６ クリーニングブレード
９７ 転写用紙[0001]
[Industrial application fields]
The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a laser printer, and a facsimile. More specifically, the present invention relates to an image forming apparatus including a cleaning unit that removes residues remaining on a member such as an image information forming body after a series of image forming processes.
[0002]
[Prior art]
As shown in FIG. 16, an image forming apparatus using an electrophotographic method generally has an aluminum base coated with an organic photoconductor layer (hereinafter referred to as an OPC layer), Se, a-Si (amorphous silicon) or the like on the surface. A charging unit 91, a developing unit 93, a transfer unit 94, and a charge eliminating unit 95 are provided to face a photosensitive drum 90 that is an image information forming body configured by the above.
[0003]
When the photosensitive drum 90 rotates in the clockwise direction (indicated by an arrow A in the figure), the surface of the photosensitive drum 90 is given a uniform charged charge by corona discharge or the like of the charging means 91, and exposure of an image scanner, LED, etc. (not shown) is performed. Upon receiving exposure according to the image information by means 92, an electronic latent image such as an electrostatic latent image, a charge latent image, or a conductive latent image is formed.
[0004]
Charged fine particles having an average particle size of 10 to 20 μm, which are colored with carbon black or the like, using polystyrene or styrene-acrylic copolymer as a binder resin from the one-component or two-component developing means 93 for this electron latent image. The toner 81 is supplied, and the electronic latent image is visualized by the toner 81 to form a visible image (hereinafter referred to as a toner image) using the toner.
[0005]
A transfer paper 97 as a transfer material is conveyed between the photosensitive drum 90 and the transfer means 94 by a paper supply means (not shown), and the toner 81 that has formed a visible image on the surface of the photosensitive drum 90 is corona of the transfer means 94. The toner is transferred from the photosensitive drum 90 to the transfer paper 97 by electric discharge.
[0006]
The transfer paper 97 onto which the toner 81 has been transferred is discharged by a paper discharge means (not shown), is heated or pressurized by a fixing means (not shown), the toner 81 is melted, and is transferred onto the transfer paper 97 formed by the toner 81. The image is fixed on the surface of the transfer paper 97.
[0007]
After the toner 81 is transferred to the transfer paper 97, the residual charge is eliminated by using light or corona discharge.
[0008]
In the transfer step in which the toner 81 is transferred to the transfer paper 97 by the transfer means 94 in the image forming process described above, the toner image formed on the surface of the photosensitive drum 90 is entirely transferred to the transfer paper 97 by the transfer means. is not. That is, in the transfer process, the image is transferred to the transfer sheet 97 with an efficiency of about 80%, and the remaining about 20% remains as residual toner 82 on the surface of the photosensitive drum 90. Further, on the surface of the photosensitive drum 90, in addition to the residual toner 82, products generated by corona discharge such as the charging unit 91 and the transfer unit 94 and deposits 83 such as paper powder and talc contained in the transfer sheet 97 are adhered. The residual toner 82 and the deposit 83, which are these residues, have an adverse effect during the execution of the next image forming process, and there is a possibility that image quality will be deteriorated due to charging failure and image flow.
[0009]
Therefore, a cleaning member such as a cleaning blade 96 made of an elastic member such as urethane rubber or a fur brush or the like in which a brush made of a polymer such as nylon or acrylic is planted is disposed between the transfer means 94 and the charge eliminating means 95. Then, the tip of the cleaning blade 96 or the like is brought into pressure contact with the surface of the photosensitive drum 90 to scrape off the residual toner 82 and the deposit 83 attached to the surface of the photosensitive drum 90 after the transfer process is finished. I am doing so.
[0010]
As the cleaning means, there are a fur brush and a cleaning roller in addition to the cleaning blade 96, which also presses a cleaning member such as a fur brush and a cleaning roller against the surface of the photosensitive drum 90 as in the case of the cleaning blade 96. It is.
[0011]
In addition, as disclosed in Japanese Patent Publication No. 5-17552 and Japanese Patent Publication No. 5-23436, an air suction port or an air blowing port is provided in the vicinity of the surface of the photosensitive drum so that the residual toner does not contact the surface of the photosensitive drum. There is a method of air suction or spraying that collects or collects and deposits.
[0012]
Further, as disclosed in JP-A-62-67577, the rotating shaft is disposed in parallel to the photoreceptor, and the metal roller is disposed with a gap between the surface of the photosensitive drum, In some cases, a recovery bias obtained by superimposing an AC bias voltage on a DC bias voltage is applied to a metal roller so that toner is electrostatically adsorbed on the surface of the metal roller for cleaning.
[0013]
Furthermore, as disclosed in Japanese Examined Patent Publication No. 47-42340, a cleaning blade is disposed as a cleaning means, and further, a collection member made of a biased roll having conductivity is disposed on the upstream side of the cleaning blade, Japanese Patent Application Laid-Open No. Sho 62 for improving the method of applying a DC bias voltage to this biasing roll and electrostatically attracting and collecting the residual toner removed by the cleaning blade, and Japanese Patent Publication No. 47-42340 There is No.12480.
[0014]
The cleaning means using these cleaning members not only cleans the photosensitive drum which is an image information forming body, but also cylindrical or belt-like members (belt-like image information forming body) such as a charging roller, a transfer roller, and a fixing roller. It is effective for cleaning the surface of
[0015]
[Problems to be solved by the invention]
However, in the case of using a cleaning member that strongly presses against the surface of the photosensitive drum, such as a cleaning blade or a fur brush, the cleaning blade or brush is a photosensitive drum or a cylindrical or belt-shaped member that is an image information forming body. The desired cleaning performance cannot be obtained unless the pressure is mechanically strongly pressed.
[0016]
Further, although the toner is removed, the OPC layer of the photosensitive drum is gradually scraped by rubbing with a cleaning member such as a cleaning blade in order to make strong pressure contact, or the cleaning member such as the cleaning blade and the photosensitive drum Adherents bite between the OPC layer and damage the OPC layer, causing severe damage, leading to a reduction in image quality and a major obstacle in extending the service life.
[0017]
Further, residual toner, talc, and discharge products such as discharge products come into contact with cleaning members such as a magnetic brush, transfer paper, and a cleaning blade of the developing unit and are crushed and adhere to the surface of the photosensitive drum as a film. It is known to cause filming, which is also a factor of deterioration in image quality.
[0018]
In addition, toner (hereinafter referred to as waste toner), which is charged fine particles collected by a cleaning member such as a cleaning blade, also includes deposits other than toner, such as paper dust and talc, which have adhered to the photosensitive drum. ing. In the toner recycling mechanism that collects and recycles the waste toner as it is, if an adhering material other than these toners is contained at the same time as the toner, it acts as an impurity, friction charging by stirring in the developing means, toner layer formation and development characteristics It is known that the collected toner becomes difficult to regenerate, and is one of the important factors in constructing a toner recycling mechanism.
[0019]
Further, in the method of sucking air or blowing air close to the surface of the photosensitive drum, which is disclosed in Japanese Patent Publication No. 5-17552 and Japanese Patent Publication No. 5-23436, a relatively large suction device or blowing device is provided in the image forming apparatus. It is necessary to provide it. In the former air suction method, when used continuously for a long period of time, in the filter that separates deposits such as residual toner, paper dust and talc from the air suction port and the sucked air, the sucked residual toner and deposits are clogged. As a result, there has been a problem that the suction force is lowered and the maintenance of the filter is required regularly. On the other hand, in the latter air blowing method, a cleaning blade is provided in pressure contact with the surface of the photosensitive drum in order to effectively introduce air to the surface of the photosensitive drum, and this cleaning blade causes filming of residual toner, talc, and the like. In addition, there is a problem of causing damage due to paper dust and the like, and it is also necessary to maintain a filter for separating residual toner and adhered matter from the discharged air.
[0020]
Further, a metal roller disclosed in Japanese Patent Laid-Open No. 62-67577 is provided with a gap between the surface of the photosensitive drum and a recovery bias in which an AC bias voltage is superimposed on a DC bias voltage is applied. Therefore, in the method of electrostatically adsorbing toner on the surface, there is a problem that it is difficult to remove deposits other than toner such as paper dust and talc.
[0021]
Furthermore, in the method disclosed in Japanese Patent Publication No. 47-42340, there is provided a collecting member that is a biased roll having conductivity, and the residual toner removed by the cleaning blade is collected by electrostatic suction. The upper limit and the lower limit of the voltage applied to the bias roller are defined, and the bias voltage applied to the biasing roller is assumed to be a DC voltage, and is used in combination with a cleaning blade. On the other hand, in Japanese Patent Laid-Open No. 62-12180, the upper and lower limits of the potential of the conductive roller, which is the biasing roller of Japanese Patent Publication No. 47-42340, are defined by the gap between the conductive roller and the photosensitive drum. Is applied in combination with a cleaning blade. The technique disclosed above is basically used in combination with a cleaning blade, and does not eliminate the influence on the photosensitive drum by using the cleaning blade, and the bias voltage applied to the biasing roller or the conductive roller. There is an effective range other than the potential range.
[0022]
The present invention has been made paying attention to the problems as described above. The first object of the present invention is to efficiently remove toner that is charged fine particles on the surface of the image information forming body in a non-contact manner. Another object of the present invention is to provide an image forming apparatus provided with a cleaning unit that can maintain stable cleaning performance without deterioration in image quality.
[0023]
In addition, the second purpose is to enable removal of toner, paper dust, talc and other adhering particles that are charged fine particles on the surface of the image information forming body depending on the type of the image information forming body. An object of the present invention is to provide an image forming apparatus provided with a cleaning unit that can prevent filming of adhering substances such as toner and talc, and realize a long life and high speed of an image information forming body.
[0024]
Furthermore, another object of the present invention is to easily regenerate the collected toner, which is a problem in constructing a toner recycling mechanism, and has an adverse effect on frictional charging due to agitation in the developing means, toner layer formation and development characteristics. An object of the present invention is to provide an image forming apparatus provided with no cleaning means and recovery / conveyance means.
[0025]
[Means for Solving the Problems]
The present invention forms an electronic latent image such as an electrostatic latent image, a charge latent image, or a conductive latent image on the surface of an image information forming body by electrophotography, and uses polystyrene or a styrene-acrylic copolymer as a binder resin. The image is visualized by charged fine particles such as toner, and the charged fine particles are transferred onto a transfer material such as transfer paper, the residue remaining on the transferred image information forming body is cleaned, and the charged fine particles on the transfer material are heated. The image forming apparatus executes a series of image forming processes for fixing by adding, for example.
[0026]
According to a first aspect of the present invention, the cleaning unit of the image forming apparatus is disposed so as to face the image information forming body surface or at least one of charged fine particles such as toner on the image information forming body with a gap therebetween, and A collecting body that collects charged fine particles on the information forming body, and a bias voltage (hereinafter referred to as cleaning) that is used for cleaning having an arbitrary size and frequency in the gap between the collecting body and the image information forming body. Power supply means for applying a voltage). The power supply means sets the surface potential in the cleaning area of the image information forming body to V in the cleaning area where the recovery body faces the image information forming body.₀ , The DC bias voltage of the cleaning voltage applied to the recovery body is V_D C Then, if the charged polarity of the charged fine particles is positive, V₀ > V_D C If a cleaning voltage is applied so that the charging polarity of the charged fine particles is negative, V₀ <V_D C A cleaning voltage is applied so that
[0027]
According to a second aspect of the present invention, in the cleaning area where the cleaning means of the image forming apparatus similar to the first aspect of the invention faces the image information forming body, the power source means is in the cleaning area of the image information forming body. A cleaning voltage is applied such that a potential difference ΔV between the surface potential and the DC bias voltage of the cleaning voltage applied to the recovery body is 50 V or more and 350 V or less.
[0028]
According to a third aspect of the present invention, in the cleaning area where the cleaning means of the image forming apparatus similar to the first aspect of the invention faces the image information forming body, the power supply means is in the cleaning area of the image information forming body. The surface potential is V₀ Void discharge start voltage of the gap_B Then, the surface potential V in the cleaning area of the image information forming body₀ And the half amplitude voltage value V of the potential by the cleaning voltage applied to the recovery body with reference to the reference is 500 V or more and V_B A cleaning voltage is applied so as to be as follows.
[0029]
As a combination of the first to third inventions, first, as a first combination, an image is formed in a cleaning region facing an image information forming body of a cleaning unit of an image forming apparatus similar to the first invention. The surface potential in the cleaning region of the information forming body is V₀ , The DC bias voltage of the cleaning voltage applied to the recovery body is V_D C Then, if the charging polarity of the charged fine particles is positive, the power supply means₀ > V_D C If a bias voltage is applied so that the charging polarity of the charged fine particles is negative, V₀ <V_D C The bias voltage is applied so that the potential difference ΔV between the surface potential in the cleaning region of the image information forming body and the DC bias voltage of the cleaning voltage applied to the recovery body is 50 V or more and 350 V or less. A voltage is applied.
[0030]
As a second combination, the surface potential in the cleaning area of the image information forming body in the area facing the image information forming body of the cleaning unit of the image forming apparatus similar to the first invention is expressed as V.₀ , The DC bias voltage of the cleaning voltage applied to the recovery body is V_D C Void discharge start voltage of the gap_B Then, if the charging polarity of the charged fine particles is positive, the power supply means₀ > V_D C If a cleaning voltage is applied so that the charging polarity of the charged fine particles is negative, V₀ <V_D C The cleaning voltage is applied so that the potential difference ΔV between the surface potential in the cleaning region of the image information forming body and the DC bias voltage of the cleaning voltage applied to the recovery body is 50 V or more and 350 V or less. A voltage is applied, and the surface potential V in the cleaning area of the image information forming body₀ And the half amplitude voltage value V of the potential by the cleaning voltage applied to the recovery body based on the_B A cleaning voltage is applied so as to be as follows. Further, the present invention is not limited to the first and second combinations described above, and each can be effectively combined.
[0031]
Further, according to a fourth aspect of the present invention, the cleaning unit of the image forming apparatus includes a first cleaning unit that removes toner from the surface of the image information forming body, and image information formation on the downstream side of the image forming process of the first cleaning unit. This is a cleaning unit for an image forming apparatus having a second cleaning unit for removing deposits other than toner from the surface of the body. The first cleaning means of the image forming apparatus is arranged to face the surface of the image information forming body or at least one of the charged fine particles such as toner on the image information forming body with a gap therebetween, and the image information forming body. A first recovery body for recovering the upper charged fine particles, and a bias voltage used for cleaning having an arbitrary size and frequency in the gap between the first recovery body and the image information forming body. Power supply means for applying a cleaning voltage). Then, the surface potential in the cleaning area of the image information forming body is set to V in the cleaning area facing the cleaning means.₀ , The DC bias voltage of the cleaning voltage applied to the first recovery body is V_D C Then, if the charging polarity of the charged fine particles is positive, the power supply means₀ > V_D C If a cleaning voltage is applied so that the charging polarity of the charged fine particles is negative, V₀ <V_D C The cleaning voltage is applied so that the potential difference ΔV between the surface potential in the cleaning region of the image information forming body and the DC bias voltage of the cleaning voltage applied to the recovery body is 50 V or more and 350 V or less. A voltage is applied.
[0032]
Furthermore, it is possible to take a new configuration by combining the main part of the invention related to the recovery body of the first to third inventions with the part related to the first recovery body of the fourth invention.
[0033]
That is, in the cleaning area facing the image information forming body of the cleaning means of the image forming apparatus similar to the fourth invention, the surface potential in the cleaning area of the image information forming body is V₀ , The DC bias voltage of the cleaning voltage applied to the first recovery body is V_D C Void discharge start voltage of the gap_B Then, if the charging polarity of the charged fine particles is positive, the power supply means₀ > V_D C If a cleaning voltage is applied so that the charging polarity of the charged fine particles is negative, V₀ <V_D C The cleaning voltage is applied so that the potential difference ΔV between the surface potential in the cleaning region of the image information forming body and the DC bias voltage of the cleaning voltage applied to the recovery body is 50 V or more and 350 V or less. A voltage is applied, and the surface potential V in the cleaning area of the image information forming body₀ And the half amplitude voltage value V of the potential by the cleaning voltage applied to the first recovery body with reference to the first recovery body is 500 V or more and V_B A cleaning voltage is applied so as to be as follows.
[0034]
Furthermore, the fifth invention is an image forming apparatus for executing a series of image forming processes for forming an electronic latent image by an electrophotographic method, visualizing the image, transferring the image onto a transfer material, and cleaning the remaining residue. The cleaning means for the entire image forming apparatus includes at least an image information forming body such as a photosensitive drum or a transfer drum on which charged fine particles such as toner adhere to the surface, a cylindrical shape such as a charging roller or a transfer roller, or a photosensitive belt or a transfer belt. The removal member for removing charged fine particles such as toner from the sheet-like member is a gap in at least one of the cylindrical or sheet-like member surface or charged fine particles such as toner adhering to the cylindrical or sheet-like member surface. An arbitrary size and frequency in the gap between the removing member disposed opposite to each other and the cylindrical member or the sheet-like member on the removing member And a power supply means for applying a bias voltage (cleaning voltage) to be used for an cleaning with like.
[0035]
If the charging polarity of the charged fine particles such as toner to be removed is positive, the power source means sets the DC bias voltage of the cleaning voltage applied to the removing member to the toner or the like in the cleaning region of the cylindrical or sheet-like member. When the cleaning voltage is applied so as to be smaller than the surface potential including the charged fine particles and the charged polarity of the charged fine particles such as the toner to be removed is negative, the DC bias voltage of the cleaning voltage applied to the removing member is A cleaning voltage is applied so as to be higher than the surface potential including charged fine particles such as toner in the cleaning region of the cylindrical or sheet-like member. Furthermore, the potential difference ΔV between the surface potential including charged fine particles such as toner in the cleaning region of the cylindrical or sheet-like member and the DC bias voltage of the cleaning voltage applied to the removing member is 50 V or more and 350 V or less. When the cleaning voltage is applied, the one-amplitude voltage value of the potential by the cleaning voltage applied to the removal member with reference to the surface potential including charged fine particles such as toner in the cleaning region of the cylindrical or sheet-like member is The cleaning voltage is applied so as to be 500 V or more and not more than the gap discharge start voltage of the gap.
[0036]
Furthermore, a sixth invention is the invention according to the fourth and fifth inventions, wherein a toner using polystyrene or a styrene-acrylic copolymer as a binder resin removed by the first cleaning means is used. A collection conveyance unit is provided that collects the image information from the image information forming body and conveys it to the developing unit.
[0039]
Furthermore, a new configuration can be taken by combining the fourth invention with the sixth to seventh inventions. That is, in the image forming apparatus according to the fourth aspect of the present invention, the developing means that visualizes with charged fine particles such as toner is a magnetic or non-magnetic one-component non-contact developing means, and the image forming means is formed on the surface of the image information forming body by the transferring means. When the charged fine particles such as toner among the remaining residues are cleaned by the first cleaning unit, the first cleaning unit removes charged fine particles such as toner on the surface of the image information forming body or the image information forming body. At least one is provided with a first recovery body arranged to face with a gap, and power supply means for applying a bias voltage to the gap between the first recovery body and the image information forming body. The power supply means determines the surface potential in the cleaning area of the image information forming body as V.₀ The DC bias voltage of the cleaning voltage applied to the first recovery body of the first cleaning means is V_D C Void discharge start voltage of the gap_B Then, if the charging polarity of the charged fine particles is positive, the power supply means₀ > V_D C If a bias voltage is applied so that the charging polarity of the charged fine particles is negative, V₀ <V_D C The cleaning voltage is applied so that the potential difference ΔV is 50 V or more and 350 V or less. Further, the surface potential V in the cleaning area of the image information forming body₀ And the half amplitude voltage value V of the potential by the cleaning voltage applied to the first recovery body with reference to the first recovery body is 500 V or more and V_B A cleaning voltage is applied so as to be as follows, and a collection conveyance unit is provided that collects charged fine particles such as the toner removed from the image information forming body by the first cleaning unit and conveys them to the development unit. It is characterized by that.
[0040]
The collection body of the cleaning means or the first collection body of the first cleaning means of the present invention is a cylindrical or sheet-like member, and the collection body or the first collection body is between the image information forming body and the first collection body. In order to apply a bias voltage to the air gap, metal materials such as aluminum, copper, and iron and their alloy materials, conductive carbon particles and fillers (hereinafter referred to as conductive particles), carbon fibers, etc. A conductive or semiconductive material obtained by dispersing and containing a conductive material such as fiber (hereinafter referred to as conductive fiber) in a polymer material such as urethane or silicone, that is, a non-insulating material. Since these materials only need to have conductivity, polymers such as the above-mentioned carbon rubber dispersed in carbon fiber in conductive rubber such as urethane rubber and silicone rubber, plastic materials, and engineering plastics. In addition, it is also possible to use conductive foamed urethane, conductive ceramic, conductive porous material, functionally graded material, and the like.
[0041]
These collection bodies or the first collection bodies are slightly against at least one of the surface of the image information forming body such as a photosensitive drum, a photosensitive belt, and a transfer belt, or charged fine particles such as toner on the image information forming body. Are arranged opposite each other. The collection body or the first collection body is applicable as a removing member that removes charged fine particles such as the toner on the image information forming body. Further, the removal target to which the residue is attached is not limited to an image information forming body in which an OPC layer is applied to the surface of a drum base or a belt base, but may be a cylindrical or sheet-like member. In addition, the fixing roller and the like can take various forms regardless of their forms. The cylindrical member here includes a drum base and a roller, and the sheet-like member includes a belt base and a film.
[0042]
In the configuration of the present invention, the void on the surface of the image information forming body such as the photosensitive drum of the collecting body or the first collecting body or the charged fine particles such as the toner on the image information forming body is formed on the collecting body or the first collecting body. It is sufficient that the body is disposed so as not to contact at least one of the image information forming body or the charged fine particles such as toner on the image information forming body and in a non-contact manner while maintaining a desired gap, The size of the gap depends on the cleaning efficiency of the cleaning means of the image forming apparatus, the specifications of the power supply, the processing method, the processing accuracy, the difficulty of assembly, the cost, etc. It is thought that.
[0043]
The image information forming body according to the present invention comprises a Se alloy such as Se and Se—Te / Se, zinc oxide, CdS, a-Si, and an organic photoconductor (OPC) on the surface of a drum base, a belt base and a sheet base. It is formed by vapor deposition or coating. The configuration of the image information forming body is roughly classified into a single layer type constituted by one type of photosensitive layer, and a function separation type provided with a carrier generation layer (CGL) and a carrier transport layer (CTL).
[0044]
In the former, a carrier generating material (CGM) is uniformly dispersed in a carrier transport material (CTM), an optical carrier is generated by the CGM, and the optical carrier moves in the CTM. In the latter, CGL is stacked on CTL (a protective layer may be provided in the uppermost layer in some cases), and optical carriers generated in CGL move in CTL.
[0045]
For these image information forming bodies, Se, a-Si, an organic photoconductor (OPC), etc. described above are used. In recent years, phthalocyanine-based materials that respond to demands for cost, printing durability, durability, and high sensitivity are used. OPC has been increasing production, and it is obvious that these image information forming bodies can be used in the present invention.
[0046]
The power supply means for applying a cleaning voltage to be used for cleaning having an arbitrary size and frequency in the gap between the recovery body or the first recovery body and the image information forming body is a high-voltage power supply device. High-voltage positive and negative DC bias voltage can be output in any magnitude, and at the same time, any low-voltage DC bias voltage, AC bias voltage or DC bias voltage input from the external input terminal to AC bias voltage Can be amplified and output as a high-voltage AC voltage, and a DC bias voltage can be arbitrarily applied.
[0047]
Moreover, since the waveform of the low-voltage AC bias voltage input from the external input terminal or the AC bias voltage of the oscillating voltage obtained by superimposing the AC bias voltage on the DC bias voltage may be a waveform suitable for use in cleaning, Not only a sine wave but also various waveforms such as a rectangular wave and a pulse wave can be used. The output voltage, frequency, and phase are determined by the frequency characteristics of the power supply means, the type of load (resistive load, capacitive load, inductive load, etc.), the size of the air gap, and the physical properties of charged fine particles such as toner to be removed. In general, it also changes due to load fluctuations and temporal fluctuations.
[0048]
The developing means of the image forming apparatus according to the present invention can be applied to any of one-component or two-component developing means, contact or non-contact developing means, magnetic or non-magnetic developing means. In the configuration according to the fourth aspect of the present invention, the magnetic or non-magnetic one-component non-contact developing system is used.
[0049]
The developing unit of the one-component non-contact development method includes a toner carrier that carries charged fine particles such as toner on the surface, a toner supply member that supplies the charged fine particles from the hopper to the toner carrier, and a carrier that is carried on the toner carrier. A layer regulating member for forming a thin layer of charged fine particles such as the toner, a layer regulating member press-contacting mechanism that presses the layer regulating member against the toner carrier, and the toner carrier and the image information forming body. Development bias power supply means for applying a bias voltage therebetween is provided.
[0050]
The toner carrier is disposed opposite to the surface of the image information forming body or at least one of charged fine particles such as toner on the image information forming body with a gap. Further, the toner supply member is disposed to face or not contact the toner carrier, and supplies a necessary amount of charged fine particles such as toner from the hopper to the toner carrier. Furthermore, the layer restricting member has a restricting member such as urethane fixed to at least one surface of the support member with an adhesive member, and the layer restricting member press-contact mechanism is configured such that the layer restricting member is directly on the toner carrier or from the side. It is elastically pressed by a member such as a spring. The developing bias power supply means applies a voltage so as to be a reverse bias with respect to the surface potential of the surface of the image information forming body, and a potential difference between the surface potential of the surface of the image information forming body and the bias voltage by the developing bias power supply means, That is, the developing potential is set appropriately (for example, so as not to cause fogging).
[0051]
The transfer unit of the image forming apparatus according to the present invention is a transfer unit using an electrostatic transfer system. This transfer means sandwiches a transfer material such as transfer paper between the image information forming body and the transfer means, and charges the back surface by a corona discharge having a polarity opposite to that of charged fine particles such as toner to be electrostatically adsorbed on the transfer material. It is given from (transfer means side). At this time, charged fine particles such as toner are attracted to the charge of the opposite polarity applied to the transfer material and adhere to the transfer material. This corona discharge imparting member is generally called a corona discharger, and is made of a conductive material, an insulating material, or a shield case made of a material in which an insulating material is coated on the surface of a conductive material, such as tungsten. A thin wire is stretched, and the opening of the shield case is arranged to face the image information forming body. A direct bias voltage of 5 to 7 kV is generally applied to the wire by a transfer bias power source, and charged fine particles such as toner are electrostatically attracted and transferred to a transfer material.
[0052]
The collecting and conveying means of the image forming apparatus according to the present invention collects the toner removed from the image information forming body by the collecting body or the first collecting body, and discharges the toner from the cleaning means. It is conveyed to developing means such as developing means. The toner adhering to the surface of the collection body or the first collection body is peeled off from the surface of the collection body or the first collection body by a peeling member such as a blade. Then, the collected and peeled toner is conveyed to the developing means by a conveying auger, a coil spring or the like disposed in a conveying pipe connecting the cleaning means and the developing means. Further, a toner regeneration unit that regenerates the collected toner may be provided in the transport path, or a toner regeneration unit may be provided in the developing unit.
[0053]
[Action]
As described above, an electronic latent image is formed on the surface of the image information forming body by the electrophotographic method, visualized by charged fine particles such as toner, transferred to the transfer material, and remains on the image information forming body. In the image forming apparatus that executes a series of image forming processes for cleaning the residue and fixing the charged fine particles on the transfer material, the cleaning means or the first cleaning means according to the present invention is a collection body of the cleaning means ( Hereinafter, the first recovery body (hereinafter simply referred to as the first recovery body) of the first cleaning means is charged on the surface of the image information forming body or the toner on the image information forming body. At least one of the fine particles is disposed to face each other with a gap. And it has a power supply means which applies a bias voltage to the said space | gap between the said collection body or a 1st collection body and an image information formation body.
[0054]
The recovery body according to the present invention or the first recovery body is disposed opposite to the photosensitive drum, which is an image information forming body such as Se, a-Si, or OPC having photoconductivity. The area is called a cleaning area. The cleaning voltage applied to the cleaning area by the power source means the size of this gap, the film thickness and relative dielectric constant of the photoconductive layer (dielectric layer) of the photosensitive drum, the layer thickness and ratio of charged fine particles such as toner. The pressure is divided by the value of the dielectric constant and applied to the gap.
[0055]
The void electric field strength due to the voltage applied to the void is obtained from the voltage applied to the void and the surface potential in the cleaning region including charged fine particles such as toner on the image information forming body. Voltage V applied to this gap_g (V) represents the bias voltage applied by the power supply means as V_a (V) The surface potential in the cleaning area including charged fine particles such as toner on the image information forming body is expressed as V.₀ Assuming (V), it is expressed as shown in Equation 1.
[0056]
[Expression 1]

[0057]
Where d_t : Layer thickness of charged fine particles (m)
d_o : Film thickness of image information forming body (m)
ε_t : Dielectric constant of charged fine particles
ε_o : Dielectric constant of image information forming body
g: Size of gap (m)
It is. Also, V_g Void electric field strength E due to_g Is expressed as Equation 2 using Equation 1.
[0058]
[Expression 2]

[0059]
In the actual configuration, the voltage applied to the air gap represented by Equations 1 and 2 and the air gap electric field strength are the cleaning voltage applied by the power supply means and the cleaning including charged fine particles such as toner on the image information forming body. It is obtained from the potential difference of the surface potential in the region. That is, if this potential difference is large, the Coulomb force acting on charged fine particles such as toner becomes large. Coulomb force F acting on charged fine particles such as toner_e Is the charge of charged fine particles such as toner, q, and the void electric field strength is E._g Then, the repulsive force between the charged fine particles such as toner and the surface potential in the cleaning region including the charged fine particles such as toner on the image information forming body, the image force, and the van der Waals force act. .
[0060]
[Equation 3]

[0061]
Equation 3 shows a case where a DC bias voltage is applied to the cleaning region. When an AC bias voltage or an oscillating voltage obtained by superimposing the AC bias voltage on the DC bias voltage is applied, not only the Coulomb force but also dynamics. Force (impact force caused by collision between charged fine particles such as toner) also acts. Also, unlike the case of only the DC bias voltage described above, the Coulomb force acts on the Coulomb force caused by the oscillating electric field obtained from the peak-to-peak voltage of the oscillating voltage.
[0062]
The present applicant applied a collision avalanche model that best represents the flying of charged fine particles such as toner in this oscillating electric field during cleaning to the cleaning means of the present invention. This collision avalanche model was applied to developing means by Mr. Yanagida and others of Fuji Xerox Co., Ltd. In this model, charged fine particles such as toner first fly from the toner carrier toward the image information forming body, and the reverse flying charged fine particles that return to the toner carrier by the AC bias voltage become charged fine particles on the toner carrier. The charged fine particles fly to the image information forming body by colliding and separating the charged fine particles from the toner carrier by a mechanical force.
[0063]
When this model is applied to cleaning, the equation of motion in the case where one charged fine particle such as a spherical toner to be cleaned moves in the air by an electric field is expressed as shown in Equation 4 in consideration of the viscous resistance of air. Is done. In this case, the position at time t in the direction connecting the rotation center of the image information forming body and the rotating body is x (t).
[0064]
[Expression 4]

[0065]
Where q: charge amount of one charged fine particle (C)
m: Mass of one charged fine particle (kg)
r: radius of one charged fine particle (m)
η: Air viscosity coefficient (Pa · s)
f: Frequency of AC bias voltage (Hz)
E: Cleaning electric field (V / m) in the cleaning region
E_A C : Cleaning electric field (V / m) by AC bias voltage
E_D C : Cleaning electric field by DC bias voltage (V / m)
It is.
[0066]
In the collision avalanche model, the flying of charged fine particles such as toner efficiently occurs under a specific bias application condition, which can be called a flying resonance phenomenon. When Equation 4 is solved for x (t), Equation 5 is obtained.
[0067]
[Equation 5]

[0068]
Where τ: damping coefficient m / (6πηr)
C: Capacitance (F) of the air gap in the cleaning area
V_A C : Peak-to-peak voltage of cleaning bias AC bias voltage (V)
V_P   : Surface potential (V) in the cleaning area of the image information forming body
V_D C : DC bias voltage (V) for cleaning voltage
ε₀   : Dielectric constant in vacuum (F / m)
It is.
[0069]
This number 5 indicates that the distance between the image information forming body and the recovery body, that is, the gap, depends on various parameters such as the frequency of the AC bias voltage and the magnitude of the cleaning voltage. The resonance conditions (hereinafter referred to as “flight resonance”) in which charged fine particles such as toner fly here are complicated because the parameters shown in Equations 4 and 5 affect each other.
[0070]
Therefore, the charged fine particles such as toner have a half cycle time t of the AC bias voltage of the cleaning voltage₀ If the flight resonance occurs when moving from the collection body onto the image information forming body, the frequency of the AC bias voltage at this time, that is, the flight resonance frequency f₀ Using time t₀ Is expressed as in Equation 6.
[0071]
[Formula 6]

[0072]
X (t when flight resonance occurs₀ ) Is equal to the gap g between the image information forming body and the collection body. Therefore, Equation 5 becomes Equation 7.
[0073]
[Expression 7]

[0074]
From Equation 7, the flying of charged fine particles such as toner is the flying resonance frequency f.₀ It depends on the frequency of the AC bias voltage of the cleaning voltage applied in. If the frequency, charge amount or specific charge of charged fine particles such as toner are constant, flight resonance such as the magnitude of the bias voltage of the cleaning voltage and the surface potential in the cleaning region including the charged fine particles on the image information forming body. Depends on the bias application conditions.
[0075]
For example, in the present invention as an example, as shown in FIG. 2, when a cleaning voltage having an AC bias voltage with an AC bias voltage frequency of 2.5 kHz to 12 kHz is applied, flying of charged fine particles such as toner efficiently occurs. And good cleaning properties can be obtained.
[0076]
According to Equation 7, the flying efficiency and cleaning characteristics of charged fine particles such as toner are determined by the surface potential in the cleaning region of the image information forming body and the DC bias voltage of the cleaning voltage applied to the collection body or the first collection body. It is shown that the voltage difference ΔV also depends on the peak-to-peak voltage of the AC bias voltage of the cleaning voltage. That is, even when an AC bias voltage having the same frequency cleaning voltage is applied, the potential difference between the surface potential in the cleaning region of the image information forming body and the DC bias voltage of the cleaning voltage applied to the recovery body or the first recovery body. If ΔV does not match the condition of flight resonance, good cleaning properties may not be obtained. Conversely, the AC bias voltage of the cleaning voltage even at the same frequency and the same potential differenceofIf the peak-to-peak voltage is not applied with a specific magnitude, it does not match the condition of flight resonance, and good cleaning properties cannot be obtained.
[0077]
This means that when a cleaning voltage is applied to clean charged particles such as toner with the recovery body or the first recovery body, a flight threshold voltage exists in the bias application condition of flight resonance. The flying threshold voltage under the bias application condition is the difference between the surface potential in the cleaning area of the image information forming body and the DC bias voltage of the cleaning voltage applied to the recovery body or the first recovery body, and the AC bias of the cleaning voltage. Related to voltage peak-to-peak.
[0078]
First, the former regulates the direct current potential in the cleaning area of the image information forming body, and varies depending on the charging polarity of charged fine particles such as toner. The cleaning means of the present invention comprises at least one of charged fine particles such as toner on the surface of the image information forming body or on the image information forming body, or the toner attached to the surface of the cylindrical or sheet-like member or the surface of the cylindrical or sheet-like member. 3 is constituted by a recovery body or a first recovery body, or a removal member that is disposed opposite to at least one of the charged fine particles, and the regulation of the direct current potential will be described with reference to FIG. To do.
[0079]
The surface potential of the image information forming body or the cylindrical or sheet-like member is a potential including charged fine particles such as toner on the image information forming body. That is, when charged fine particles such as toner are not attached to the surface, it is a surface potential due to the surface charge of the image information forming body or cylindrical or sheet-like member, and charged fine particles such as toner are attached to the surface. Is the sum of the surface potential due to the surface charge of the image information forming body or cylindrical or sheet-like member and the surface potential due to the charge of charged fine particles such as toner. This surface potential is usually negatively charged because the image information forming body or cylindrical or sheet-like member can move a lot of negative photocarriers, and the surface has a large negative potential. . Further, charged fine particles such as toner adhere to the surface of the image information forming body or the cylindrical or sheet-like member in a positively or negatively charged state, and the potential as a whole is negatively biased. .
[0080]
On the other hand, the DC potential of the recovery body or the first recovery body or the removal member is determined by the power supply means of the image forming apparatus so that flight resonance occurs and the recovery body or the first recovery body or the removal member fly to the recovery body. The potential is defined by applying a DC bias voltage of the cleaning voltage with reference to the surface potential of the image information forming body or the cylindrical or sheet-like member. If the charged polarity of charged fine particles such as toner is positive, a DC bias voltage smaller than the surface potential of the image information forming body or cylindrical or sheet-like member is applied, and if the charged polarity of charged fine particles such as toner is negative A DC bias voltage larger than the surface potential of the image information forming body or the cylindrical or sheet-like member is applied. When this is expressed by a mathematical formula, it becomes as shown in Expression 8.
[0081]
[Equation 8]

[0082]
The surface potential in the cleaning region of the image information forming body and the DC bias voltage of the cleaning voltage applied to the recovery body or the first recovery body are determined by the DC bias voltage of the cleaning voltage applied by the power supply device of the image forming apparatus. When the potential difference ΔV (Equation 9) is in the range of 50V to 350V, the cleaning property is improved.
[0083]
[Equation 9]

[0084]
Next, the relationship between the peak-to-peak voltage of the AC bias voltage of the latter cleaning voltage defines the potential between the amplitude value due to the application of the AC bias voltage and the surface potential of the image information forming body or the cylindrical or sheet-like member. is there. This potential regulation will be described with reference to FIG.
[0085]
As described above, the surface potential of the image information forming body or the cylindrical or sheet-like member is usually negatively charged on the surface, and the potential is largely negatively biased. In the present invention, the cleaning body, the first recovery body, or the removing member is cleaned by applying a cleaning voltage in which an AC bias voltage is superimposed on a DC bias voltage.
[0086]
In FIG. 4, the waveform of the AC bias voltage of the cleaning voltage applied by the power supply unit of the image forming apparatus is a sine wave, a rectangular wave, or the like, and the half amplitude value V obtained from the peak-to-peak voltage of the cleaning voltage application waveform itself._H A Is
[0087]
[Expression 10]

[0088]
Thus, the smaller one of the half amplitude values obtained from Equation 10 is particularly meaningful. However, this half amplitude value is the DC bias voltage V of the cleaning voltage._D C Therefore, the cleaning property cannot be considered only by this value, and the surface potential of the image information forming body or the cylindrical or sheet-like member is related.
[0089]
What actually contributes to cleaning is the potential relationship between the potential due to the cleaning voltage such as an oscillating voltage obtained by superimposing the AC bias voltage on the DC bias voltage and the surface potential of the image information forming body or the cylindrical or sheet-like member (the cleaning potential The surface potential of the image information forming body or the cylindrical or sheet-like member is used as a reference. That is, it is a potential by the cleaning voltage applied to the recovery body or the first recovery body or the removal member based on the surface potential in the cleaning area of the image information forming body or the cylindrical or sheet-like member, and its one-amplitude value V is
[0090]
## EQU11 ##

[0091]
The smaller one of the amplitude values obtained from Equation 11 is the reverse flight potential in the collision avalanche model, and the larger value is the flight potential in the collision avalanche model, which is related to the cleaning property. The value needs to be greater than or equal to the flight threshold voltage. This is a flying mechanism of charged fine particles such as toner in a collision avalanche model. In addition to the flying to the collection body, the first collection body, or the removing member, the reverse flight of charged fine particles such as toner occurs and the toner etc. The charging effect of the charged fine particles is important. Naturally, the potential difference between the cleaning voltage applied to the gap and the surface potential of the image information forming body or the cylindrical or sheet-like member, that is, the cleaning so that no discharge is generated in the cleaning area of the image information forming body during the application of the cleaning voltage. The single amplitude value of the potential needs to be equal to or lower than the gap discharge start voltage of the gap.
[0092]
In the fourth, sixth, seventh and eighth inventions of the present invention, the cleaning means of the image forming apparatus includes a first cleaning means for removing toner from the surface of the image information forming body, and a first cleaning means. The second cleaning means for removing mainly deposits other than toner from the surface of the image information forming body is provided downstream of the image forming process. In the first cleaning means, the cleaning voltage described above is applied to the first recovery body to remove charged fine particles such as toner. Thereafter, the second cleaning unit comes into contact with the image information forming body to remove the residue remaining on the image information forming body.
[0093]
According to a sixth aspect of the present invention, in the fourth and fifth aspects, the toner separated or removed by the first cleaning unit is not discarded outside the image forming apparatus, but is entirely or partially conveyed to the developing unit. A collection transport means is provided. The collecting and conveying means sequentially conveys the toner removed from the image information forming body by the first collecting body of the first cleaning means and the toner collected by the rotation of the conveying auger and coil spring in the conveying pipe. Then, the toner is returned to the hopper of the developing means and the toner is recycled. According to the present invention, if the normal development characteristics do not deteriorate, it may be returned directly to the developing means, or depending on the case, a process for improving the development characteristics may be performed during conveyance or when the developing means is returned to the developing means. .
[0094]
In the seventh aspect of the present invention, the developing unit of the image forming apparatus is a magnetic or non-magnetic one-component non-contact developing unit, and not only the cleaning unit but also the developing unit uses a non-contact mechanism. The occurrence of damage and filming on the surface of the image information forming body due to contact development such as the brush development method is further reduced.
[0095]
In the eighth invention of the present invention, the transfer unit of the image forming apparatus is a scorotron transfer unit, and after the transfer process by the scorotron transfer unit ensures transfer of toner onto a transfer material such as transfer paper, The influence of charging on charged fine particles such as toner remaining on the information forming body and the image information forming body is reduced. Thereby, it is possible to reduce the influence of the charge on the cleaning performance by the cleaning means, and it is possible to always maintain a certain cleaning performance.
[0096]
【Example】
Embodiments of the image forming apparatus according to the present invention will be described below.
[0097]
(Example 1)
FIG. 1 is a schematic configuration diagram of a first embodiment of an image forming apparatus according to the present invention. A photosensitive drum 10 which is an image information forming body of the present embodiment has a cylindrical aluminum drum base and an organic photoconductor layer (OPC layer) formed on the outer peripheral surface of the drum base with a diameter of 50 mm and a long length. It has a thickness of 313 mm, and rotates clockwise (A direction) at a predetermined peripheral speed (process speed), for example, 175 mm / s. Here, the image information forming body 10 is not limited to the drum base, but may be a hollow or solid cylindrical shape or a sheet shape, and the rotation direction is not limited to the A direction. The material is not limited to aluminum, and a protective layer or a lower layer may be provided between the OPC layer and the drum base.
[0098]
The surface of the photosensitive drum 10 that rotates in the A direction is charged with a polarity opposite to that of toner that is charged fine particles in the developing process by a charger that is a charging unit (not shown), and exposure according to image information is performed by an exposure unit (not shown). In response, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 10, and the toner is developed and visualized by a developing unit (not shown), and then transferred to a transfer material by a transfer unit (not shown). Transfer to the surface of the paper. On the surface of the photosensitive drum 10 after passing through the transfer unit, untransferred toner (residual toner) 7, which is charged fine particles such as toner remaining on the photosensitive drum, paper dust, talc, and the like. It is attached.
[0099]
The cleaning device 1 serving as a cleaning unit includes a cleaning roller 2 that is a collection body that is disposed so as to be opposed to at least one of the surface of the photosensitive drum 10 or the residual toner 7 on the photosensitive drum 10, and the photosensitive drum 10 on the cleaning roller. And a blade of urethane rubber or the like for scraping off the toner collected by the cleaning roller from the surface of the cleaning roller 2 as a power supply means for applying a cleaning voltage as a bias voltage to be used for cleaning the gap between 4. The cleaning roller 2 rotates in the counterclockwise direction (B direction) with a minute gap d so that its rotation axis is parallel to the rotation axis of the photosensitive drum 10.
[0100]
The cleaning roller 2 is made of metal materials such as aluminum, copper, and iron, and alloy materials thereof, carbon particles and fillers having conductivity (hereinafter referred to as conductive particles), and fibers such as carbon fibers (hereinafter referred to as conductive materials). A conductive or semiconductive material in which a conductive material such as urethane is dispersed in a polymer material such as urethane or silicone, that is, a non-insulating material. Since these materials only need to have conductivity, polymers such as the above-mentioned carbon rubber dispersed in carbon fiber in conductive rubber such as urethane rubber and silicone rubber, plastic materials, and engineering plastics. In addition, it is also possible to use conductive foamed urethane, conductive ceramic, conductive porous material, functionally graded material, and the like.
[0101]
By configuring the cleaning roller 2 with a conductive material, that is, a non-insulating material, it is possible to use metal materials having excellent strength and wear resistance or alloy materials thereof. Can be applied. Further, the cleaning roller 2 is made of a conductive or semiconductive polymer material containing conductive materials such as conductive carbon particles, conductive particles such as filler, and conductive fibers such as carbon fibers. By doing so, it is possible to obtain a cleaning roller that is lighter than a metal material or the like while maintaining strength. Furthermore, the cleaning roller 2 may have a multilayer structure in which the surface of the cleaning roller 2 is coated with a conductive or semiconductive polymer material.
[0102]
The cleaning roller 2 of this embodiment is a hollow cylindrical metal roller made of aluminum having a diameter of 12 mm and a length of 252 mm, the surface is smooth, and the gap d with respect to the photosensitive drum 10 is 200 μm. The value of the gap d can be arbitrarily set according to mechanical restrictions such as processing accuracy and material strength, and electrical restrictions such as voltage applied to the gap and prevention of discharge.
[0103]
For example, a vibration voltage obtained by superimposing an AC bias voltage on a DC bias voltage is applied to the cleaning roller 2 from the power supply device 3 as a cleaning voltage. The residual toner 7 remaining on the surface of the photosensitive drum 10 is electrostatically attracted to the surface of the cleaning roller 2 by a Coulomb force by the DC bias voltage of the cleaning voltage. The toner that is electrostatically attracted to and adhered to the cleaning roller 2 is scraped off by the blade 4 that contacts the surface of the cleaning roller 2 and is collected in a collection bottle (not shown) or the like.
[0104]
The surface potential of the photosensitive drum 10 is a potential including charged fine particles such as toner on the photosensitive drum, and when charged fine particles such as toner are not attached to the surface, the surface potential is a surface potential due to the surface charge of the photosensitive drum. When charged fine particles such as toner adhere, the sum of the surface potential due to the surface charge of the photosensitive drum and the surface potential due to the charge of charged fine particles such as toner. The photosensitive drum of this embodiment has a negative charging characteristic, has a negative surface charge, and the surface potential is about −500 V after the development process, and −900 after the transfer process using the corotron transfer device. It is negatively biased up to about -1000V. Further, charged fine particles such as toner adhere to the surface of the photosensitive drum 10 in a state of being charged about 20V to 200V positively or negatively, though there are differences depending on each step of the image forming process. The potential as a whole is negatively biased.
[0105]
When the cleaning voltage is applied to the photosensitive drum 10 in such a state to remove the residual toner 7 from the photosensitive drum 10, the DC bias voltage V of the cleaning voltage applied by the power supply device 3._D C And the surface potential V of the photosensitive drum 10 described above.₀ There is a big difference in the cleaning properties from the relationship. FIG. 5 shows an example of the result of examining the cleaning property based on the magnitude relationship between the DC bias voltage and the surface potential. In FIG. 5, when the charge polarity of the residual toner 7 is positive (+), V in (1)₀ > V_D C In the case of (3) V₀ <V_D C In this case, the cleaning property deteriorates. When the charging polarity of the residual toner 7 is negative (−),₀ > V_D C In the case of (3) V₀ <V_D C In this case, the cleaning property is improved. Furthermore, V in (2)₀ = V_D C In this case, a very small amount may be cleaned depending on the minute potential distribution state in the cleaning region between the photosensitive drum 10 and the cleaning roller 2.
[0106]
Next, the present applicant applies a cleaning voltage to the photosensitive drum 10 to remove the residual toner 7 from the photosensitive drum 10, and the DC bias voltage V of the cleaning voltage applied by the power supply device 3._D C And the surface potential V of the photosensitive drum 10 described above.₀ It was found that when the potential difference between the first and second toners is in a specific range, the flying of the residual toner 7 from the photosensitive drum 10 to the cleaning roller 2 is promoted, and the cleaning property is improved. An example of the relationship between the cleaning voltage and the potential difference ΔV between the DC bias voltage of the cleaning voltage and the surface potential of the photosensitive drum 10 is shown in FIG. In FIG. 6, if the potential difference ΔV is about 50V to 350V, good cleaning efficiency is shown. As a result of an experiment under various conditions, the DC bias voltage V of the cleaning voltage is obtained by the power supply device 3 which is a power supply means for applying the cleaning voltage._D C And the surface potential V of the photosensitive drum 10₀ When a cleaning voltage is applied such that the potential difference ΔV is 50 V or more and 350 V or less, good cleaning properties are exhibited and an excellent image forming apparatus can be configured.
[0107]
The dimensions, structure, material, peripheral speed and the like of the photosensitive drum 10, the cleaning roller 2, and the blade 4 are not limited to those described above, and various types are conceivable. For example, the photosensitive drum has a diameter of 80 mm, a length of 358 mm, and a cleaning. The same applies to a roller having a diameter of 20 mm and a length of 310 mm.
[0108]
(Example 2)
FIG. 7 is a schematic configuration diagram of a second embodiment of the image forming apparatus according to the present invention. The image forming apparatus is the same as that of the first embodiment, and the main structure such as the structure and material of the cleaning roller 2 of the cleaning device which is the photosensitive drum 10 and the cleaning unit are also the same. In FIG. 7, a power supply device 3 which is a power supply means for applying a cleaning voltage to the cleaning roller 2 has a DC power supply circuit 13 for applying a DC bias voltage and an AC power supply circuit 14 for applying an AC bias voltage. In particular, it shows that an oscillating voltage in which an AC bias voltage is superimposed on a DC bias voltage is applied. For example, as the oscillating voltage, the DC bias voltage is set to +200 V or −200 V, the AC bias voltage is applied with a frequency of 3 kHz, and a peak-to-peak voltage of 2 kVp-p. The frequency of the AC bias voltage, the peak-to-peak voltage, and the magnitude of the DC bias voltage are not limited to those described above, and various values can be applied.
[0109]
The photosensitive drum 10 which is an image information forming body of the present embodiment also has a cylindrical aluminum drum base and an organic photoconductor layer (OPC layer) formed on the outer peripheral surface of the drum base with a diameter of 50 mm and a long length. 313 mm long, rotating at a predetermined peripheral speed (process speed), for example, 175 mm / s, clockwise (A direction), and the cleaning roller 2 is a hollow cylinder made of aluminum with a diameter of 12 mm and a length of 252 mm The surface of the metal roller is smooth and the gap d with respect to the photosensitive drum 10 is 200 μm.
[0110]
When cleaning is performed by applying an oscillating voltage in which an AC bias voltage is superimposed on a DC bias voltage to the cleaning roller 2, the contribution to the cleaning is based on the surface potential in the cleaning region of the photosensitive drum 10 that is an image information forming body. This is the potential relationship obtained from the single amplitude value V of the potential (cleaning potential) due to the cleaning voltage applied to the cleaning roller 2 which is the collected body.
[0111]
The applicant of the present invention has disclosed that the flying potential and the reverse flying potential of the toner 7 in the flying mechanism in which the single amplitude value of the cleaning potential is represented by the collision avalanche model is equal to or higher than the flying threshold voltage, and the photosensitive drum is cleaned while the cleaning voltage is being applied. It has been found that good cleaning properties can be obtained if it is below the gap discharge start voltage so that no discharge occurs in the region. FIG. 8 shows an example of the result of examining the single amplitude value of the cleaning potential and the cleaning property. As shown in FIG. 8, the cleaning property has a threshold value with respect to the single amplitude value of the cleaning potential.
[0112]
As a result of experiments conducted under various conditions, a cleaning voltage was applied to the cleaning roller 2 by the power supply device 3 which is a power supply means for applying a cleaning voltage, and the surface potential in the cleaning region of the photosensitive drum 10 was used as a reference. By setting the single amplitude value of the cleaning potential by the cleaning voltage to be approximately 500 V or more and not more than the gap discharge start voltage, it is possible to configure an excellent image forming apparatus that exhibits good cleaning properties.
[0113]
Note that the dimensions, structures, materials, peripheral speeds, and the like of the photosensitive drum 10, the cleaning roller 2, and the blade 4 are not limited to those described above, and various types can be considered.
[0114]
(Example 3)
FIG. 9 is a schematic configuration diagram of a third embodiment of the image forming apparatus according to the present invention. A photosensitive drum 10 which is an image information forming body of this embodiment has a cylindrical aluminum drum base and an outer diameter of 50 mm and an organic photoconductor layer (OPC layer) formed on the outer peripheral surface of the drum base. It has a thickness of 313 mm, and rotates clockwise (A direction) at a predetermined peripheral speed (process speed), for example, 175 mm / s. Here, the structure, material, and the like of the photosensitive drum 10 are not limited to the drum base as described in the first embodiment, and may be a hollow or solid cylindrical shape or a sheet shape, and the rotation direction is also the A direction. It is not limited to.
[0115]
The image forming process of the image forming apparatus shown in the present embodiment is almost the same as that described in the first embodiment, but the cleaning unit of the image forming apparatus is a first cleaning that mainly removes toner from the surface of the photosensitive drum. A first cleaning roller 2 that is a first recovery body of the means, and a second cleaning that mainly removes deposits other than toner from the surface of the photosensitive drum 10 on the downstream side of the image forming process of the first cleaning roller 2. It has the 2nd cleaning roller 5 which is the 2nd collection body of a means. The first cleaning roller 2 is the same as that described in the first embodiment, and is disposed opposite to the photosensitive drum surface or at least one of charged fine particles such as toner on the photosensitive drum with a gap d. As in the first embodiment, the power supply device 3 is a power supply unit that applies a cleaning voltage as a bias voltage to be used for cleaning the gap between the first cleaning roller and the photosensitive drum 10, and the first cleaning roller. The first cleaning blade 4 scrapes off the toner collected on the cleaning roller from the surface of the first cleaning roller 2.
[0116]
The cleaning roller 2 of this embodiment is a hollow cylindrical metal roller made of aluminum having a diameter of 12 mm and a length of 252 mm, the surface is smooth, and the gap d with respect to the photosensitive drum 10 is 200 μm. The value of the gap d can be arbitrarily set according to mechanical restrictions such as processing accuracy and material strength, and electrical restrictions such as voltage applied to the gap and prevention of discharge. In addition, the toner removal mechanism and the like are the same as those in the first embodiment.
[0117]
In the present embodiment, the cleaning voltage is applied by the power supply device 3 in the same manner as in the first embodiment, and the cleaning performance varies depending on the magnitude relationship between the DC bias voltage and the surface potential.
[0118]
For example, when the charge polarity of the residual toner 7 is positive (+), V in (1) is the same as in FIG.₀ > V_D C In the case of (3) V₀ <V_D C In this case, the cleaning property deteriorates. When the charging polarity of the residual toner 7 is negative (−),₀ > V_D C In the case of (3) V₀ <V_D C In this case, the cleaning property is improved. Further, the DC bias voltage V of the cleaning voltage applied by the power supply device 3 is used._D C And the surface potential V of the photosensitive drum 10 described above.₀ When the potential difference is within a specific range, the flying of the residual toner 7 from the photosensitive drum 10 to the cleaning roller 2 is promoted, and excellent cleaning properties are exhibited. A potential difference ΔV between the DC bias voltage of the cleaning voltage and the surface potential of the photosensitive drum 10 exhibits good cleaning properties when a cleaning voltage of, for example, 50 V or more and 350 V or less is applied, and an excellent image forming apparatus can be configured. . Furthermore, a cleaning voltage is applied to the cleaning roller 2 by the power supply device 3 which is a power supply means for applying a cleaning voltage, and the single amplitude value of the cleaning potential by the cleaning voltage based on the surface potential in the cleaning region of the photosensitive drum 10 is used. Is generally set to 500 V or more and the gap discharge start voltage or less, it is possible to form a good image forming apparatus with good cleaning properties.
[0119]
The second cleaning means includes a second cleaning roller 5 that is a second recovery body and a second blade 6 that scrapes mainly deposits other than toner from the surface of the second cleaning roller 5. Yes. The second cleaning roller 5 is in soft contact with the rotation axis of the second cleaning roller 5 parallel to the rotation axis of the photosensitive drum 10, and presses and slides on the surface of the photosensitive drum 10 to rotate in the clockwise direction (C direction). . The second cleaning roller 5 is made of an insulating elastic material, and is, for example, a cylindrical roller made of a polymer organic material such as an insulating solid rubber or porous foamed sponge rubber. The second cleaning roller 5 may be a brush roller made of a polymer organic material such as an insulating fiber. The second cleaning roller 5 may be made of a conductive or semiconductive elastic material that is a non-insulating material in addition to the insulating elastic material.
[0120]
By configuring the second cleaning roller 5 with an insulating material, it is possible to use a polymer organic material such as solid rubber or porous foam sponge rubber formed of urethane, silicon or the like having excellent moldability and productivity. it can. In addition, since the second cleaning roller 5 is made of a non-insulating material, a bias voltage is applied to the second cleaning roller 5 and, in addition to the action of removing deposits when no bias is applied, the static cleaning is further reduced. The removal effect by electric power can also be largely provided.
[0121]
In the image forming apparatus shown in FIG. 9 of the present embodiment, the second cleaning roller 5 is a solid cylindrical insulating elastic roller made of independent foam urethane having a diameter of 12 mm, a length of 252 mm, and an Asker C hardness of 50 °. Then, it is pressed against the surface of the photosensitive drum 10 at a pressure of 200 gf / cm. This pressing can be arbitrarily set based on the structure of the photosensitive drum 10, the surface material, the smoothness of the surface, the process speed, etc. so as to be softly pressed so as not to damage the surface of the photosensitive drum.
[0122]
Residues remaining on the surface of the photosensitive drum 10 are removed by the first cleaning unit and the second cleaning unit described above. First, an oscillation voltage in which an AC bias voltage is superimposed on a DC bias voltage, which is a cleaning voltage, is applied to the first cleaning roller 2 with respect to the photosensitive drum 10 after the transfer process by the first cleaning means, and the photosensitive drum 10 The residual toner 7 remaining on the surface of the toner is removed, and then the second cleaning roller 5 on the downstream side is slidably pressed against the photosensitive drum, whereby the deposit 8 other than the toner, such as paper dust and talc. Remove.
[0123]
The first cleaning roller 2 mainly removes the residual toner 7 by the same mechanism as in the first embodiment. The residual toner 7 removed by the first cleaning roller 2 is scraped off from the surface of the first cleaning roller by the first blade 4 that contacts the surface of the first cleaning roller.
[0124]
The second cleaning roller 5 is slidably pressed against the surface of the photosensitive drum 10, and mainly removes the deposits 8 other than the toner from the surface of the photosensitive drum by a mechanical shearing force. The deposit 8 removed by the second cleaning roller 5 is scraped off from the surface of the second cleaning roller 5 by the second blade 6 that comes into contact with the surface of the second cleaning roller 5. The residual toner 7 is separated and recovered.
[0125]
FIG. 10 shows an example of an image forming apparatus in which the configuration of the present embodiment shown in FIG. 9 is slightly changed so that the second cleaning roller 5 is a conductive or semiconductive elastic material that is a non-insulating material. Show. In the figure, the second cleaning roller 5 is a polymer organic material such as solid rubber or porous foam sponge rubber containing a conductive material such as carbon having a diameter of 12 mm and a length of 252 mm. Resistance value is 1 × 10⁷ ~ 1x10⁹ Ω · cm foamed urethane sponge rubber and foamed silicone sponge rubber. Moreover, in the same figure, although the 2nd cleaning roller 5 was made into sponge, it is good also as solid rubber. If the volume resistance value of the second cleaning roller 5 is out of the above range, a desirable cleaning property cannot be obtained. For example, the volume resistance value is 1 × 10⁷ In the case of less than Ω · cm, the eddy current causes the deposit 8 to form a film on the surface.⁹ When it is larger than Ω · cm, the variation of the resistance value of the material itself becomes large, and the cleaning property is deteriorated. The second cleaning roller 5 is connected to a second power supply device that applies a DC bias voltage to the outside.
[0126]
As a result of various investigations, the peripheral speed ratio of the first cleaning roller 2 to the photosensitive drum 10 is determined by rotating the photosensitive drum 10 in the direction opposite to the rotation direction (B direction) within a range of 50% to 500%. The collected residual toner 7 can be collected and removed without scattering from the first cleaning roller 2. When the range of the peripheral speed ratio is preferably 100% to 300%, the cleaning property of the residual toner 7 from the surface of the photosensitive drum 10 is further improved, and an extremely good cleaning property can be obtained.
[0127]
Further, as a result of various studies, the peripheral speed ratio of the second cleaning roller 5 to the photosensitive drum 10 is rotated in the direction opposite to the rotation direction of the photosensitive drum 10 (C direction) within a range of 50% to 500%. Thus, the deposit 8 other than the toner can be removed. Specifically, the cleaning performance is improved when the peripheral speed ratio is 100% or more, and when the peripheral speed ratio exceeds 200%, the mechanical shearing force between the second cleaning roller 5 and the surface of the photosensitive drum 10 is increased. By rotating the second cleaning roller 5 in a range of preferably 100% to 200%, good cleaning properties can be obtained.
[0128]
The power supply device 3 which is a power supply means in this embodiment includes a DC power supply circuit 13 for applying a DC bias voltage and an AC power supply circuit 14 for applying an AC bias voltage in order to apply a cleaning voltage. The cleaning voltage is, for example, a gap d of 200 μm and the surface potential V of the photosensitive drum 10.₀ Is -500V, DC bias voltage V_D C -300V, AC bias voltage peak-to-peak voltage V_A C Is 2 kVp-p, and its frequency is 3 kHz. In this way, if the charge polarity of the residual toner 7 is positive, V₀ > V_D C The residual toner 7 can be easily removed, and the potential difference ΔV between the surface potential in the cleaning area of the photosensitive drum 10 and the DC bias voltage of the cleaning voltage applied to the first cleaning roller can be applied. However, it is 50V or more and 350V or less. Further, 2 kVp-p is applied as an AC bias voltage of the AC power supply device, an electrostatic vibration force is applied to the residual toner 7, and a mechanical force is applied to the residual toner 7 by the movement of the toner, so that the photosensitive drum Remove from 10 surfaces. The AC bias voltage only needs to apply an electrostatic vibration force to the residual toner 7, and its frequency and amplitude value are also arbitrary. The applied waveform is not limited to a sine wave, but is a rectangular wave, triangular wave, rectangular wave, rectangular wave. For example, a rectangular wave having a frequency of 12 kHz can be used as a cleaning voltage in the case of this embodiment as long as it is an applied waveform for oscillating with a DC bias voltage as a boundary. May be applied. The cleaning voltage application condition is not limited to the above case, and the frequency is 500 to 15 kHz, the peak-to-peak voltage is 500 V to 5 kVp-p, preferably the frequency is 1 to 15 kHz, and the peak-to-peak voltage is 1 to -4 kVp-p. The absolute value of the DC bias voltage is 50V to 400V, preferably 50V to 350V.
[0129]
Further, since the second cleaning roller 5 is made of a non-insulating material, a DC bias voltage of about several tens to several hundreds of volts is applied or grounded by the second power supply device as shown in FIG. May be.
[0130]
The dimensions, structure, material, peripheral speed, etc. of the photosensitive drum 10, the first cleaning roller 2 and the second cleaning roller 5, the first blade 4 and the second blade 6 are not limited to those described above. Various cases are conceivable. For example, the same applies to the case where the photosensitive drum has a diameter of 80 mm and a length of 358 mm, and the cleaning roller has a diameter of 20 mm and a length of 310 mm.
[0131]
(Example 4)
FIG. 11 is a schematic configuration diagram of a fourth embodiment of the image forming apparatus according to the present invention. The basic configuration is the same image forming apparatus as in the third embodiment. A photosensitive drum 10 which is an image information forming body of this embodiment has a cylindrical aluminum drum base and an outer diameter of 50 mm and an organic photoconductor layer (OPC layer) formed on the outer peripheral surface of the drum base. It has a thickness of 310 mm, and rotates clockwise (A direction) at a predetermined peripheral speed (process speed), for example, 175 mm / s. Here, the structure, material, and the like of the photosensitive drum 10 are not limited to the drum base as described in the first embodiment, and may be a hollow or solid cylindrical shape or a sheet shape, and the rotation direction is also the A direction. It is not limited to.
[0132]
The image forming process of the image forming apparatus shown in the present embodiment is the same as that described in the third embodiment, but the cleaning unit of the image forming apparatus is a first cleaning unit that mainly removes toner from the surface of the photosensitive drum. A first cleaning roller 2 as a first recovery body, and a second cleaning means for removing mainly deposits other than toner from the surface of the photosensitive drum 10 on the downstream side of the image forming process of the first cleaning roller 2. The second cleaning roller 5 is a second recovery body. The first cleaning roller 2 is the same as that described in the first embodiment, and is disposed opposite to the photosensitive drum surface or at least one of charged fine particles such as toner on the photosensitive drum with a gap d. As in the first embodiment, the power supply device 3 is a power supply unit that applies a cleaning voltage to the first cleaning roller 2 as a bias voltage used for cleaning the gap between the photosensitive drum 10 and the first cleaning roller 2, and the first The first cleaning roller 2 has a first blade 4 that scrapes off the toner collected from the surface of the first cleaning roller 2.
[0133]
The second cleaning means has a second cleaning roller 5 that is a second recovery body and a second blade 6 that scrapes mainly deposits other than toner from the surface of the second cleaning roller 5. The second cleaning roller 5 is in soft contact with the rotation axis of the second cleaning roller 5 parallel to the rotation axis of the photosensitive drum 10, and presses and slides on the surface of the photosensitive drum 10 to rotate in the clockwise direction (C direction). .
[0134]
In addition to the above-described configuration, the image forming apparatus shown in the present embodiment includes toner and residue other than toner separated and removed by the cleaning means of the image forming apparatus, that is, the first cleaning roller 2 and the second cleaning roller 5. A collecting and conveying means for collecting and conveying certain paper dust talc and the like is provided. The collecting and conveying means includes a coil spring 23 and a conveying pipe 22 that are means for collecting and conveying the toner separated and collected by the first and second cleaning means, and performs separation and collection by this.
[0135]
The collecting / conveying means of the image forming apparatus of this embodiment removes the toner 7 remaining on the photosensitive drum 10 in a non-contact manner by the first cleaning roller 2 first, and electrostatically collects it by applying a vibration voltage. Subsequently, the second cleaning roller 5 collects the deposits 8 such as paper dust and talc in contact with the photosensitive drum. First, the residual toner 7 collected by the first cleaning roller 2 is scraped off from the surface of the first cleaning roller 2 by the first blade 4.
[0136]
The collecting and conveying means includes a coil spring 23 in a conveying pipe 22, and a thrust is applied when the coil spring 23 is twisted to convey a substance such as toner. The coil spring 23 and the transport pipe 22 which are the recovery and transport means scrape the residual toner 7 recovered by the first cleaning roller 2 with the first blade 4, and the residual toner scraped off is contained in the transport pipe 22. It enters the conveying pipe 22 by the coil spring 23, is returned to the hopper of the developing means, and is reused to execute the developing process. In the past, it was collected in a collection bottle in a state where it was mixed with residues other than toner such as paper dust and talc, and was discharged outside the machine. By configuring, most of the residual toner 7 is collected by the first cleaning roller 2, and paper dust and talc are collected separately from the residual toner 7 by the second cleaning roller 5 and discharged outside the apparatus.
[0137]
Further, the residual toner 7 separated and collected by the first cleaning roller 2 is supplied as it is into the hopper of the developing means. However, in addition to the transport pipe 22 and the coil spring 23 that constitute the recycling mechanism, the residual toner 7 is transferred to a transport path on the way. A toner regeneration processing unit 25 may be provided for appropriately processing the characteristics (particularly development characteristics) of the collected toner (hereinafter referred to as “recycled toner”) in an intermediate conveyance path. The toner regeneration processing means 25 processes the charging characteristics and the like of the recycled toner so that the developing process in the developing means exhibits desired characteristics (FIG. 12). As a result, the residual toner 7 remaining after the transfer can be efficiently removed and reused, thereby suppressing wasteful consumption of toner and executing an efficient image forming process.
[0138]
Regarding the application of the cleaning voltage in this embodiment, the magnitude of the DC bias voltage or the AC bias voltage, the potential difference from the surface potential of the photosensitive drum, the half amplitude value, and the like can be said to be the same as those in the embodiments described above.
[0139]
The dimensions, structure, material, peripheral speed, etc. of the photosensitive drum 10, the first cleaning roller 2 and the second cleaning roller 5, the first blade 4 and the second blade 6 are not limited to those described above. Various cases are conceivable. For example, the same applies to the case where the photosensitive drum has a diameter of 80 mm and a length of 358 mm, and the cleaning roller has a diameter of 20 mm and a length of 310 mm.
[0140]
(Example 5)
In the image forming apparatus shown in FIG. 13, the developing means of the image forming apparatus shown in Embodiment 3 is a magnetic or non-magnetic one-component non-contact developing means.
[0141]
The image forming process other than the developing step of the image forming apparatus shown in the third embodiment is the same as that of the third embodiment, but the conventional two-component contact developing means is a magnetic or non-magnetic one-component non-contact developing means in the developing step. As compared with the above, the developability is not inferior and, conversely, the non-contact, the damage to the photosensitive drum 10 can be reduced.
[0142]
FIG. 13 shows one using a non-magnetic non-contact developing means. In the figure, −200 V is applied as a developing bias to the developing roller 24 which is a toner carrier in the developing step. At this time, the developing roller 24 is disposed with a developing gap of about 150 μm with respect to the photosensitive drum.
[0143]
The first cleaning roller 2 as the first cleaning means is a cleaning means for removing the residual toner 7 remaining on the photosensitive drum 10 after the transfer process and the deposits 8 other than toner such as paper dust and talc. There is no contact with the photosensitive drum 10, a gap of about 200 μm is provided, and the first cleaning roller 2 is not in contact, and there is a tendency that scratches due to the cleaning blade are reduced as in the conventional case. Further, the second cleaning roller 5 is in contact with the soft touch more than when a conventional cleaning blade is used, and damage to the photosensitive drum 10 can be reduced. Further, a collecting and conveying means may be provided to add a recycling mechanism for the residual toner 7.
[0144]
(Example 6)
In the image forming apparatus shown in FIG. 14, the transfer means of the image forming apparatus shown in Embodiment 3 is a scorotron transfer means.
[0145]
The image forming process other than the transfer process of the image forming apparatus shown in the third embodiment is the same as that of the third embodiment. In order to transfer the toner image onto the transfer sheet 97 as a transfer material, the transfer unit of the conventional image forming apparatus performs transfer by applying a sufficient charge from the back surface of the transfer sheet 97 using the corotron transfer unit. However, in order to ensure sufficient transferability especially at high humidity, a large margin is provided to allow the corona discharge current to flow. When the toner image is transferred onto the transfer paper 97, extra charge is applied to the residual toner 7 remaining on the photosensitive drum 10, which affects the cleaning performance. Therefore, by using the present invention in the present embodiment, the scorotron transfer unit 30 is used as the transfer unit of the image forming apparatus, so that no excessive charge is applied to the residual toner 7 and the toner image is transferred to the transfer sheet 97. It is possible to configure an image forming apparatus capable of executing an image forming process so as not to impair the transferability.
[0146]
In the figure, the developing means may be a one-component or two-component contact / non-contact development method. The scorotron transfer means 30 as a transfer means applies a DC voltage of several kV to the discharge wire 31 or an oscillating voltage in which an AC voltage is superimposed on the DC voltage, and discharges in the vicinity of the discharge wire 31 to generate charges. At this time, in the scorotron transfer means, a grid 32 is provided between the discharge wire 31 and the photosensitive drum 10 or between the discharge wire 31 and the transfer sheet 97 to control the amount of charge applied to the photosensitive drum 10. The influence on the residual toner 7 can be reduced while ensuring the transferability. Usually, a bias voltage is applied to the grid 32 to control the surface potential of the photosensitive drum 10 and the potential of the back surface of the transfer paper 97. That is, if the potential difference between the grid 32 and the front surface of the photosensitive drum 10 or the back surface of the transfer sheet 97 is large, a large amount of charge is irradiated. Therefore, it is possible to control the amount of charge applied to the photosensitive drum 10 and the transfer paper 97 through the grid 32 from the discharge wire 31 by the grid 32. Finally, the bias voltage to the grid 32 and the photosensitive drum 10 can be controlled. When the front surface potential and the back surface potential of the transfer paper become equal, no charge passes through the grid 32.
[0147]
Regarding the application of the cleaning voltage in this embodiment, the magnitude of the DC bias voltage or the AC bias voltage, the potential difference from the surface potential of the photosensitive drum, the half amplitude value, and the like can be said to be the same as those in the embodiments described above.
[0148]
The dimensions, structure, material, peripheral speed, etc. of the photosensitive drum 10, the first cleaning roller 2 and the second cleaning roller 5, the first blade 4 and the second blade 6 are not limited to those described above. Various cases are conceivable. For example, the same applies to the case where the photosensitive drum has a diameter of 80 mm and a length of 358 mm, and the cleaning roller has a diameter of 20 mm and a length of 310 mm. Further, a collecting / conveying means may be provided to add a recycling mechanism for the residual toner 7.
[0149]
(Example 7)
In FIG. 15, an electronic latent image is formed on the surface of the image information forming body by the electrophotographic method, visualized by charged fine particles such as toner, transferred to the transfer material, and remained on the image information forming body. 1 shows an embodiment of an image forming apparatus that performs a series of image forming processes for cleaning residues and fixing charged fine particles on a transfer material.
[0150]
In this embodiment, the developing means that visualizes with charged fine particles such as toner is a magnetic or non-magnetic one-component non-contact developing means, and the transfer means that transfers charged fine particles onto the transfer material is the roller transfer means 34. It is. A bias voltage for transfer is applied to the roller transfer unit 34 from the outside.
[0151]
A first cleaning unit that electrically removes toner from the surface of the image information forming body; and toner remaining on the surface of the image information forming body on the downstream side of the image forming process of the first cleaning unit A cleaning unit having a second cleaning unit for removing residues such as charged fine particles, adhering material other than toner, such as paper powder and talc, from the image information forming body, and forming the image information by the first cleaning unit; There is provided a collecting and conveying means for collecting charged fine particles such as toner removed from the body and conveying them to the developing means.
[0152]
In addition, the first cleaning means for cleaning the surface of the image information forming body and the roller transfer means 34 of the roller transfer system, such as charged fine particles such as toner remaining on the surface of the image information forming body, paper powder, talc, etc. When the charged fine particles such as toner out of the residue such as deposits other than the toner are cleaned by the first cleaning unit, the first cleaning unit uses the toner on the surface of the image information forming body or on the image information forming body. A first collection body that is disposed opposite to at least one of the charged fine particles, such as a power supply, and a power supply unit that applies a cleaning voltage to the gap between the first collection body and the image information forming body. ing.
[0153]
Then, the power supply means sets the surface potential in the cleaning area of the image information forming body to V₀, The DC bias voltage of the cleaning voltage applied to the first recovery body is V_DCVoid discharge start voltage of the gap_BThen, if the charged polarity of the charged fine particles is positive, V₀> V_DCIf a cleaning voltage is applied so that the charging polarity of the charged fine particles is negative, V₀<V_DCAnd a potential difference ΔV between the surface potential in the cleaning region of the image information forming body and the DC bias voltage of the cleaning voltage applied to the recovery body is 50 V or more and 350 V or less. In addition, a cleaning voltage is applied so that the surface potential V in the cleaning region of the image information forming body is₀The single amplitude voltage value V of the potential by the cleaning voltage applied to the first recovery body with respect to the first recovery body is 500 V or more and_BA cleaning voltage is applied to the gap so as to be as follows.
[0154]
【The invention's effect】
According to the present invention, there is provided an image forming apparatus including a cleaning unit that can efficiently remove toner, which is a charged fine particle on the surface of an image information forming body, without contact, without deteriorating image quality, and maintaining stable cleaning performance. It can be configured, cleaning failure and discharge can be prevented, and by optimizing the bias application conditions, it can be made less susceptible to the influence of the charged state and the residue attached state on the image information forming body.
[0155]
In addition, it is possible to remove toner, paper powder, talc, and other residues that are charged fine particles on the surface of the image information forming body according to the type of the image information forming body, and damage to the surface of the image information forming body, such as toner and talc, Construct an image forming apparatus equipped with a cleaning means that can prevent filming and remove deposits other than toner, such as residual paper dust and talc, and increase the life and speed of the image information forming body. it can.
[0156]
Furthermore, the charged fine particles such as toner and paper powder are separated and collected, and the recovery of the collected toner, which is a problem in constructing the toner recycling mechanism, is easy, the friction charging by the stirring in the developing means, the toner layer formation and A cleaning unit and a recovery conveyance unit that do not adversely affect the development characteristics can be configured.
[0157]
As an additional effect, charged fine particles such as toner used in the image forming process by the electrophotographic method have a rough surface shape produced by a conventional pulverization method or the like, or a surface shape produced by a polymerization method or the like. It is also possible to remove charged fine particles such as toner that are difficult to clean with a cleaning method such as contact with or coming into contact with a cleaning blade such as a smooth one, so that it is less affected by the shape, material, characteristics, etc. of charged fine particles such as toner and is excellent in cleaning An image forming apparatus provided with a cleaning means having a property can be configured.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram showing the cleaning efficiency with respect to the frequency of the AC bias voltage of the cleaning voltage.
FIG. 3 is a diagram illustrating a relationship between a surface potential of an image information forming body and a cleaning voltage applied to a collection body.
FIG. 4 is a diagram for explaining a relationship between a surface potential of an image information forming body and an AC potential of a cleaning voltage applied to a recovery body.
FIG. 5 is a diagram showing a determination result of the cleaning property of the present invention.
FIG. 6 is a diagram showing the relationship between the cleaning voltage and the potential difference between the DC bias voltage of the cleaning voltage and the surface potential of the photosensitive drum.
FIG. 7 is a schematic configuration diagram of an image forming apparatus according to a second embodiment of the present invention.
FIG. 8 is a diagram showing a relationship between a half amplitude of an AC bias voltage applied as a cleaning voltage and cleaning efficiency.
FIG. 9 is a schematic configuration diagram of an image forming apparatus according to a third embodiment of the present invention.
FIG. 10 is a schematic configuration diagram of an image forming apparatus when a different configuration according to a third embodiment of the present invention is adopted.
FIG. 11 is a schematic configuration diagram of an image forming apparatus according to a fourth embodiment of the present invention.
FIG. 12 is a schematic configuration diagram of an image forming apparatus provided with toner regeneration processing means in a fourth embodiment of the present invention.
FIG. 13 is a schematic configuration diagram of an image forming apparatus according to a fifth embodiment of the present invention.
FIG. 14 is a schematic configuration diagram of an image forming apparatus according to a sixth embodiment of the present invention.
FIG. 15 is a schematic configuration diagram of an image forming apparatus according to a seventh embodiment of the present invention.
FIG. 16 is a schematic configuration diagram of a conventional image forming apparatus.
[Explanation of symbols]
d Air gap
1 Cleaning device
2 Cleaning roller or first cleaning roller
3 Power supply
4 Blade or first blade
5 Second cleaning roller
6 Second blade
7 Residual toner
8 Paper dust, talc and other non-toner deposits
10 Photosensitive drum
11 Second power supply
13 DC power supply circuit
14 AC power supply circuit
21 Developing means
22 Transport pipe
23 Coil spring
24 Development roller
25 Toner regeneration processing means
30 Scorotron transfer means
31 Discharge wire
32 grid
33 Shield Case
34 Roller transfer means
81 toner
82 Residual toner
83 Deposits
90 Photosensitive drum
91 Charging means
92 Exposure means
93 Developing means
94 Transfer means
95 Static neutralization means
96 Cleaning blade
97 Transfer paper

Claims (1)

An electrophotographic method forms an electronic latent image on the surface of the image information forming body, visualizes it with charged fine particles such as toner, transfers the charged fine particles onto a transfer material, and cleans the residue remaining on the image information forming body. In addition, in an image forming apparatus that executes a series of image forming processes for fixing charged fine particles on a transfer material,
A recovery body provided apart from the image information forming body, and power supply means for applying a voltage between the recovery body and the image information forming body, the surface of the image information forming body in a cleaning region the potential V _0, when the DC bias voltage of the cleaning voltage to be applied to the recovery means and V _DC, the charging polarity of said charging particles if positive, V _0> V _{D C} become so by applying a bias voltage If the charging polarity of the charged fine particles is negative, a bias voltage is applied so that V ₀ <V _{D C} and the surface potential V _{0 is set.} And the DC bias voltage V _DC And the surface potential V _{0 when} the discharge start voltage of the air gap between the image information forming body and the collection body is V _B. The half amplitude voltage value V of the potential by the cleaning voltage with respect to the reference voltage is 500 V or more, V _B Power supply means for applying a cleaning voltage is applied so that the electrostatic voltage is applied to the charged fine particles remaining on the image information forming body by applying the cleaning voltage, and the movement of the charged fine particles A first cleaning unit that applies mechanical force to the other charged fine particles remaining in the image information forming body to move the charged fine particles remaining in the image information forming body to the recovery body;
The first cleaning means has a cleaning roller provided in contact with the surface of the image information forming body on the downstream side of the image forming process, and the cleaning roller removes deposits from the surface of the image information forming body. an image forming apparatus characterized by comprising a second cleaning means.

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