JP2004021135A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To greatly increase productivity by improving reliability by maintaining a state wherein fusion is suppressed even after endurance without causing cleaning defects nor inversion of a blade by reducing an image flow by preventing the frictional force between a photoreceptor surface and a cleaning member from increasing. <P>SOLUTION: An image forming apparatus is constituted having the photoreceptor drum 2, a primary electrostatic charger 1, and an optical scanner 3. A toner image is transferred to an intermediate transfer belt 40 by developing units 33a to 33c and then transferred to a transfer material S by a secondary transfer roll 48. A cleaning device 70 which removes a residual toner from the photoreceptor drum 2 is composed of a cleaning blade and a magnetic brush, which is made to restrain polishing particles ≥10 wt.%. As cleaning by the cleaning device 70 is repeated, the mean roughness of the surface of the photoreceptor drum 2 is decreased. <P>COPYRIGHT: (C)2004,JPO

Description

【００８５】
このような球形トナーを用いることにより、常時、一次転写効率を９５％以上に確保することが可能となる。また、この第１の実施形態において感光体の表面のＳｉＣ層のモース硬度が８程度であるため、外添剤として、モース硬度が９の微粒子、具体的には平均粒径が１．２μｍのアルミナ（Ａｌ_２Ｏ_３）を１重量％外添した。
【００８６】
次に、モノクロ用の一成分現像剤について説明する。すなわち、この第１の実施形態においては、次に挙げる原料を用いてモノクロ用の磁性トナーを製造した。
ポリエステル樹脂とビニル系共重合体を混合した樹脂：１００重量部
磁性酸化鉄：９０重量部（Ｓｉ含有率：１．５重量％、平均粒径：０．２μｍ、Ｈｃ：９．５ｋＡ／ｍ、σｓ：６５ｍ^２／ｋｇ、σｒ：７Ａｍ^２／ｋｇ）
有機ジルコニウム化合物：２重量部
パラフィンワックス：５重量部
チタン酸ストロンチウム微粉体：４．０重量部
【００８７】
そして、上述した材料をヘンシェルミキサーにより前混合した後、１３０℃の温度に設定された二軸混練押し出し機（たとえば、池貝鉄工所社製、ＰＣＭ−３０）によって、溶融混練した。
【００８８】
その後、得られた混練物を冷却し、カッターミルで粗粉砕した後、ジェット気流を用いた微粉砕機で粉砕し、得られた微粉砕粉末を、コアンダ効果を利用した多分割分級機を用いて分級し、重量平均粒径７．５μｍの磁性トナーを得た。
【００８９】
得られた磁性トナーは、体積平均粒径が７μｍのトナーに関して、体積平均粒径＝４μｍ以下の微粉トナーの割合が２０％以下であり、体積平均粒径＝１５μｍ以上の粗粉トナーの割合が５％以下であった。
【００９０】
研磨粒子としては、ダイヤモンド（モース硬度（以下同様）：１５）、炭化ホウ素（１４）、炭化珪素（１３）、チタンカーバイド（１３）、酸化アルミニウム（１２）、サファイヤ（１２）、ルビー（１２）　、コランダム（１２）などの、モース硬度が高い粒子が望ましい。
【００９１】
また、研磨粒子の寸法は、感光体ドラム２の表面を研磨する際に擦過痕が入らずに鏡面となるように決定される。具体的には、その砥粒サイズの上限は、擦過痕の大きさが画像認識サイズの数十μｍに比して十分小さくなるように、設定されている。そして、この設定によれば、砥粒サイズは、ＪＩＳ−Ｒ−６００１の規格による＃８００以上のものが好適である。
【００９２】
黒トナー用の現像手段を構成する部分としての一成分磁性現像装置５０は、図１に示すように、例えば感光体ドラム２と同極性のネガトナーを収容する。また、マグネットの磁力は、現像スリーブ５１の表面上において、磁極Ｎ_１：８６ｍＴ（８６０ガウス）、磁極Ｓ_１：９５ｍＴ（９５０ガウス）、磁極Ｎ_２：７５ｍＴ（７５０ガウス）、磁極Ｓ_２：６６ｍＴ（６６０ガウス）となるものが採用される。
【００９３】
また、一方の現像処理を担う磁極Ｓ_１は、現像スリーブ５１を介して感光体ドラム２に対面配置される。他方のトナー層規制を担う磁極Ｎ_１は、現像スリーブ５１を介して規制ブレードに対面配置されている。
【００９４】
この第１の実施形態においては、一方の現像スリーブ５１および感光体ドラム２の最近接間隔は、１５０〜３００μｍとすることが望ましい。他方、現像スリーブ５１および規制ブレードの間隙は、１５０〜３００μｍとすることが望ましい。
【００９５】
さらに、現像スリーブ５１の周速度は、感光体ドラム２の周速度の１２０〜１９０％程度に設定するのが望ましい。
【００９６】
また、電源（図示せず）から現像スリーブ５１に印加される現像バイアスとしては、ピーク間電圧Ｖｐｐ＝１．０〜２．０ｋＶ、周波数ｆ＝１．０〜２．０ｋｓ^−１、およびＤｕｔｙ＝２０〜５０％の交流電圧に１００〜４００Ｖの直流電圧が重畳されたバイアスが好ましい。
【００９７】
なお、Ｋトナーは、上述のように磁性トナーであることが好ましい。そして、この磁性トナーは、ガラス転移温度４０〜６０℃を有する結着樹脂を１００重量部とし、これに少なくとも、固体ワックスを０．２〜２０重量部および磁性体を１０〜２００重量部有して構成される。
【００９８】
ガラス転移温度が４０〜６０℃である結着樹脂としては、スチレン系のスチレンアクリル共重合体、スチレンブタジエン共重合体などの、フェノール樹脂およびポリエステルなどを挙げることができる。
【００９９】
また、ガラス転移温度（Ｔｇ）の測定方法は、示差走査熱量計（ＤＳＣ測定装置）（たとえば、パーキンエルマー社製、ＤＳＣ−７）を用いて、ＡＳＴＭ　Ｄ３４１８−８２に準じて測定されるものである。
【０１００】
具体的には、測定試料を５ｍｇ精秤してアルミパンに入れ、リファレンスとしての空のアルミパンを用い、温度範囲を３０〜２００℃としつつ昇温速度を１０℃／ｍｉｎとして測定を行う。この昇温過程において、４０〜１００℃の温度範囲におけるＤＳＣ曲線にメインピークの吸熱ピークが得られる。
【０１０１】
このときの吸熱ピークが現れる前後のベースラインの中間点の線とＤＳＣ曲線との交点をガラス転移温度（Ｔｇ）とする。また、この第１の実施形態においては、磁性トナーとして平均粒径が６〜１０μｍ、好適には、６〜８μｍであるのが望ましい。
【０１０２】
さらに、この第１の実施形態による磁性トナーは、体積平均粒径が７μｍのトナーに関して、体積平均粒径が４μｍ以下の微粉トナーの割合が２０％以下であり、また、体積平均粒径１５μｍ以上の粗粉トナーの割合が５％以下であるのが望ましい。
【０１０３】
上述した第１の像担持体としての感光体ドラム２の表面の下方には、第２の像担持体としての中間転写体としての中間転写ベルト４０と、ベルト駆動ロール４５、テンションロール４３、アイドラロール４６、二次転写用バックアップロール４４を含む複数のベルト支持ロールと、第一転写手段としての一次転写ロール４２と、図示省略したが、それらを支持するベルトフレームとが設けられている。そして、中間転写ベルト４０は、上述のベルト支持ロールにより回転移動可能に支持されている。
【０１０４】
そして、フルカラー画像を形成する場合、潜像書込位置Ａにおいて第１色目の静電潜像が形成され、現像領域Ｂにおいて１色目のトナー像が形成される。このトナー像は、一次転写領域Ｄを通過する際に、一次転写ロール４２によって中間転写ベルト４０上に静電的に一次転写される。
【０１０５】
その後、同様にして、第１色目のトナー像を担持した中間転写ベルト４０上に、第２色目、第３色目および第４色目のトナー像が順次重ね合わされて一次転写が行われる。そして、最終的に、フルカラーの多重トナー像が中間転写ベルト４０上に形成される。
【０１０６】
なお、単色の白黒画像を形成する場合においては、一成分磁性現像装置５０のみが使用され、単色トナー像が中間転写ベルト４０上に一次転写される。
【０１０７】
この一次転写の後、感光体ドラム２の表面における残留トナーは、クリーニング装置７０によりクリーニングされる。
【０１０８】
また、給紙トレイ６０に収容された記録シートＳは、所定のタイミングを計られてピックアップロール６１により取り出され、レジロール６２に搬送される。
【０１０９】
このレジロール６２により搬送された記録シートＳは、上述の一次転写された多重トナー像または単色トナー像が二次転写領域Ｅに移動するときのタイミングに合わせられて、二次転写領域に搬送される。
【０１１０】
その後、この二次転写領域Ｅにおいて、第二転写手段としての二次転写ロール４８は、中間転写ベルト４０上のトナー像を、一括して記録シートＳに静電的に二次転写する。二次転写後、ベルトクリーナ４７によって中間転写ベルト４０から、ここに残留した残留トナーが除去される。
【０１１１】
なお、上述した二次転写ロール４８およびベルトクリーナ４７は、中間転写ベルト４０と、離隔自在および接触自在（離接自在）に配設されている。また、カラー画像が形成される場合においては、最終色の未定着トナー像が中間転写ベルト４０に一次転写されるまで、中間転写ベルト４０から離隔している。
【０１１２】
トナー像が二次転写された記録シートＳは、シート搬送ベルト６３によって、加熱ロール６４ａおよび加圧ロール６４ｂにより構成される一対の定着ロールを有する定着器６４に搬送され、加熱定着される。トナー像が定着された記録シートＳは、記録シート排出トレイ６５から装置外に排出される。
【０１１３】
中間転写ベルト４０は、ポリイミド層およびシアノレジン層（高誘電率層）の２層構造を有する。そして、この中間転写ベルト４０は以下のようにして製造される。
【０１１４】
すなわち、基層のカーボンブラックを分散した熱硬化性シームレスベルトは、カーボンブラックを耐熱皮膜用ポリイミドワニスＵ（宇部興産（株）社製）に混ぜてミキサーなどにより混合されて構成される。その後、この原液を円筒の型に注入した後、加熱を行いつつ遠心成形する。
【０１１５】
続いて半硬化した状態で脱型し、脱型したベルトを鉄芯に被せて、４００℃〜４５０℃の温度で加熱し、イミド化反応による本硬化が行われる。これにより、表面抵抗率が１０^１２Ω／□、体積抵抗率が１０^１０Ωｃｍで、厚さが７５μｍのシームレスベルトが製造される。
【０１１６】
ここで、この第１の実施形態による画像形成装置に用いられる中間転写ベルト４０は、ヤング率が２．５×１０^３ＭＰａ以上、引張強度が１．０×１０^５Ｎ／ｍ（１０００Ｎ／ｃｍ）以上であることが好ましく、ヤング率や引張強度などが高い、たとえばポリイミドのような樹脂が好ましい。
【０１１７】
一方、中間転写ベルト４０の支持ロールであるとともに、二次転写ロール４８の対向電極をなす二次転写用バックアップロール４４の層構成は、単層構造または多層構造のいずれでもよい。
【０１１８】
具体的には、層構成がたとえば単層構造の場合、二次転写用バックアップロール４４は、シリコーンゴム、ウレタンゴム、エチレンプロピレンジエンモノマー（ＥＰＤＭ）などにカーボンブラックなどの導電性微粉末が適量配合されたロールから構成される。
【０１１９】
２層構造の場合における二次転写用バックアップロール４４は、コア層とスキン層とから構成される。
【０１２０】
これらのうちのコア層は、体積抵抗率を適宜調節したシリコーンゴム、ウレタンゴムまたは、エチレンプロピレンジエンモノマー（ＥＰＤＭ）などの発泡体で構成される。
【０１２１】
また、スキン層は、導電性のシリコーンゴム、ウレタンゴムまたは、エチレンプロピレンジエンモノマー（ＥＰＤＭ）などにカーボンブラックなどの導電剤を配合して構成され、コア層の外周面に設けられる。
【０１２２】
そして、この第１の実施形態による二次転写用バックアップロール４４の体積抵抗率としては、１０^７〜１０^９Ω・ｃｍの範囲にあることが好ましい。
【０１２３】
また、上述した二次転写ロール４８は、種々の膜構成を採用することができ、特に限定されるものではない。この第１の実施形態においては、例えば、２層構造の場合に、コア層と、このコア層の表面を被覆するコーティング層とから構成されるものが用いられる。
【０１２４】
これらのうちのコア層は、導電性粉末を分散したシリコーンゴム、ウレタンゴムまたは、エチレンプロピレンジエンモノマー（ＥＰＤＭ）などから構成されるか、またはこれらの発泡体から構成される。
【０１２５】
他方、コーティング層は、導電性粉末が分散されたフッ素樹脂系の材料から構成することが好ましい。このフッ素樹脂の例を挙げると、テトラフルオロエチレン（ＴＦＥ）、ヘキサフルオロプロピレン共重合体（ＦＥＰ）、またはパーフロロアルコキシ樹脂（ＰＦＡ）などである。また、二次転写ロール４８の体積抵抗率は、１０^６〜１０^９Ω・ｃｍの範囲にあることが好ましい。
【０１２６】
また、この第１の実施形態による電子写真複写機における最大画像幅は、Ａ４横とノビ対応との約３２０ｍｍとし、ドラム周速は３００ｍｍ／ｓとする。
【０１２７】
また、感光体ドラム２は、非晶質シリコン系感光体、具体的にはシリコン原子を母体とする非単結晶材料（アモルファスシリコン、ａ−Ｓｉ）によって形成される感光層を有する感光体から構成される。アモルファスシリコン（ａ−Ｓｉ）には、水素原子、ハロゲン原子、炭素原子、酸素原子、ホウ素などの、いわゆる周期表第３Ｂ族に分類される原子や、および窒素（Ｎ）などの、いわゆる周期表第５Ｂに分類される原子などの他の原子を含むものも可能である。
【０１２８】
また、感光層は、機能の異なる層を複数積層させた積層膜が好ましい。このような積層膜としては、下部阻止層、電荷輸送層、または電荷発生層などから構成される、光導電層、バッファ層および、表面層などを挙げることができる。
【０１２９】
また、非晶質シリコン系感光体は、感光体表面の硬度の向上および感光体表面の潤滑性の向上などの観点から、最表面に水素化アモルファスカーボンから構成される表面層を有するのが、より好ましい。
【０１３０】
この水素化アモルファスカーボンは、炭素原子を母体とする非単結晶材料に水素原子が含まれた構成（ａ−Ｃ：Ｈ）を有し、上述のアモルファスシリコン（ａ−Ｓｉ）と同様の他の原子を含むものも可能である。なお、この「ａ−Ｃ：Ｈ」とは、グラファイトとダイヤモンドとの中間的な性質を有する、主としてアモルファス状炭素を表すが、微結晶や多結晶を部分的に含むものも可能である。
【０１３１】
また、表面層が形成された非晶質シリコン系感光体は、従来公知の方法によって製造することが可能である。すなわち、この非晶質シリコン系感光体の製造方法としては、たとえばプラズマ化学気相成長法（プラズマＣＶＤ法）などを利用することが可能である。
【０１３２】
このプラズマＣＶＤ法においては、まず、導電性基体を系内に設置し、この系内に、上述した原子を含む原子供給ガス（原料ガス）を導入する。その後、系内において、プラズマを発生させることにより原料ガスを分解する。そして、この分解された原料ガスの原子を反応させつつ導電性基体に気相成長させる方法である。
【０１３３】
また、このプラズマＣＶＤ法により形成される、表面層を含む感光層の膜厚や強度は、原料ガスの濃度や放電などに用いられる高周波電力により調整可能である。ここで、原料ガスとしては、水素や不活性ガス（希ガスや窒素ガス）を混合したガスを用いることが可能である。
【０１３４】
また、感光体ドラム２は、正帯電のアモルファスシリコン感光体を有して構成される。また、この感光体を有する感光体ドラム２の寸法の一例を挙げると、直径が８０ｍｍ、厚さが約３ｍｍのアルミニウムシリンダ表面に、たとえばグロー放電などによって、たとえば３０μｍの膜厚のアモルファスシリコン感光層を形成することによって構成される。なお、感光体ドラム２の表層としては、膜厚がたとえば８００ｎｍの水素化シリコンカーバイト（ＳｉＣ：Ｈ）膜を用いた。
【０１３５】
次に、クリーニング手段としてのクリーニング装置７０について説明する。すなわち、クリーニング装置７０のクリーニング容器７１には、上述した感光体ドラム２の表面に当接されたクリーニングブレード７２が保持されている。
【０１３６】
このクリーニングブレード７２は、ＪＩＳ規格において、ウレタンを主体とした弾性ブレードでモース硬度が７０度（Ｈｓ）、反発弾性率が１５％（４０℃での反発弾性率２５％）、３００％モジュラスが２００ｋｇ／ｃｍ^２の材料から構成される。また、このクリーニングブレード７２は、その板厚がたとえば２ｍｍであり、背板としてたとえば２０ｃＳＵＳ（板厚１．０ｍｍ）の部材が配設されている。
【０１３７】
また、クリーニングブレード７２は、当接角度を２４゜、当接圧を１９．６Ｎ／ｍ（２０ｇ／ｃｍ）として、感光体ドラム２に配設されている。また、クリーニングブレード７２の自由長は、たとえば３ｍｍである。
【０１３８】
また、クリーニング容器７１内の上述したクリーニングブレード７２の上流側、すなわち感光体ドラム２の回転方向に対する上流側には、磁性体保持手段としてのマグネットローラ７３が設けられている。このマグネットローラ７３は、図１中、紙面垂直方向に感光体ドラム２との間で所定間隔を隔てて設けられている。
【０１３９】
このマグネットローラ７３の表面には、磁性トナーが磁界（８極１００ｍＴ（１０００ガウス））により捕集されることにより、磁気ブラシが形成されている。また、マグネットローラ７３は、感光体ドラム２の回転方向に対する順方向に沿って、相対速度１０％の周速で回転することにより、感光体表面を摺擦可能に構成されている。
【０１４０】
また、露光走査装置１３においては、６６０ｎｍのピーク波長を主体とした、たとえばＡｌＧａＡｓ化合物素子から構成される発光ダイオードが用いられる。この発光ダイオードは、そのピーク波長の１／２になる半値幅が、たとえば約２５ｎｍであり、露光量は、たとえば２０μＪ／ｃｍ^２である。
【０１４１】
また、露光走査装置１３による前露光から一次帯電器１までの感光体表面の移動時間は、たとえば約５０ｍｍ／ｓである。
【０１４２】
さて、上述したように、感光体ドラム２は、直径が８０ｍｍ、厚さが約３ｍｍのアルミニウムシリンダ上に、グロー放電などによって厚さが３０μｍのアモルファスシリコン感光層が設けられている。さらに、この感光体ドラム２の表層として、膜厚がたとえば８００ｎｍのＳｉＣ：Ｈを積層したものが用いられる。また、そのビッカース硬度は、たとえば１１００ｋｇ／ｍｍ^２である。
【０１４３】
本発明者は、上述した非晶質シリコン系感光体を有する感光体ドラム２を用いて、高温高湿（温度が３２．５℃、湿度が８５％）の環境下において、耐久検査を行った。その結果、３００万枚の耐久後であっても画像流れの発生は生じなかった。さらに、クリーニングブレードエッジ部においても、チッピングなどの発生は見られなかった。
【０１４４】
そして、感光体ドラム２自体においても、３００万枚耐久後も融着や部分的なフィルミング層の発生や摺擦傷などの、従来発生するような問題は全く生じなかった。
【０１４５】
また、感光体ドラム２の初期の表面粗さＲｚが、０．３６μｍ（上述したＡＦＭ：捜査範囲２０μｍ×２０μｍ）であったのに対し、３００万枚の耐久後の感光体の表面粗さＲｚは、０．０８μｍであった。
【０１４６】
また、クリーニング装置のマグネットローラ上の磁気ブラシに拘束されている、たとえばアルミナ／チタン酸ストロンチウムからなる研磨粒子は、１６重量％であった。磨耗量に関しては、１０００回転当たり０．１２ｎｍ程度であった。
【０１４７】
さらに、５％ペルオキソ二硫酸ナトリウム（Ｎａ_２Ｓ_２Ｏ_８）水溶液中で、７０℃〜８０℃の温度で３０分間加熱した後、アセトン中で超音波洗浄（約１分）エタノール／純水で、リンス前後で反射分光式干渉計（大塚電子（株）製ＭＣＤＰ２０００）により、膜厚測定を行ったところ、フィルミング層は確認されなかった。
【０１４８】
（第２の実施形態）
次に、この発明の第２の実施形態による画像形成装置について説明する。この第２の実施形態における画像形成装置においては、第１の実施形態におけると異なり、黒トナーに平均粒径１．５μｍのＳｉ−Ｃを３．０重量％外添したものを用いる。そのほかの基本構成は、第１の実施形態におけると同様であるので、説明を省略する。なお、クリーニング装置におけるマグネットローラ上の磁気ブラシに拘束されている研磨粒子（アルミナ／Ｓｉ−Ｃ）は、１２重量％であった。
【０１４９】
そして、この第２の実施形態においては、高温高湿（温度が３２．５℃、湿度が８５％）の環境下で、３００万枚の耐久検査を行った後においても、画像流れの発生は生じなかった。また、クリーニングブレードエッジ部にチッピングなどの問題は発生しなかった。
【０１５０】
また、感光体ドラム２においても、３００万枚耐久後であっても、融着や、部分的なフィルミング層の発生や、摺擦傷などの画像に発生するような問題は全く生じなかった。また、３００万枚耐久後の表面粗さＲｚは、耐久検査前に対して減少し、０．１５μｍであった。
【０１５１】
この第２の実施形態による画像形成装置によれば、第１の実施形態におけると同様の効果を得ることができる。
【０１５２】
（第３の実施形態）
次に、この発明の第３の実施形態による画像形成装置について説明する。この第３の実施形態による画像形成装置においては、第１の実施形態における床となり、感光体として表面層にａ−Ｃ：Ｈ（水素化アモルファスカーボン）を１００ｎｍ積層したものを用いる。また、そのほかの基本構成は、第１の実施形態におけると同様であるので、説明を省略する。また、本発明者の実験およびそれに伴う検討によれば、水素化アモルファスカーボン（ａ−Ｃ：Ｈ）は、第２の実施形態において用いた、ＳｉＣ：Ｈからなる表面層に比して摩擦係数が小さいことが確認されている。
【０１５３】
そして、本発明者による実験によれば、高温高湿（温度が３２．５℃、湿度が８５％）環境下における、３００万枚の耐久検査の後であっても、画像流れの発生が生じないことが確認された。
【０１５４】
また、感光体ドラム２自体に関しては、３００万枚の耐久検査後においても、融着、部分的なフィルミング層の発生、クリーニング不良、摺擦傷などの、画像に発生するような問題は、全く生じなかった。なお、その際の摩耗量は、１０００回転当たり０．０２ｎｍであった。
【０１５５】
また、耐久後の摩擦係数は、低い値で維持されていることも確認された。本発明者の鋭意検討によれば、この摩擦係数が低い値で維持される理由は、水素化アモルファスカーボン（ａ−Ｃ：Ｈ）の表面自由エネルギーが、水素化シリコンカーバイト（ＳｉＣ：Ｈ）に比して小さいことにより、オゾン生成物やトナー紙粉などの有機物が、感光体の表面に付着凝着しにくくなったため、フィルミング層の形成が抑制されたことである。
【０１５６】
また、初期の表面粗さＲｚが０．２７μｍであったのに対し、３００万枚の耐久後の表面粗さＲｚは、０．１２μｍであった。また、摩耗量は１０００回転当たり５×１０^−３ｎｍであり、これも凝着摩耗が発生しにくいことに起因すると推定される。
【０１５７】
また、この第３の実施形態においては、３００万枚の耐久後であっても、高温高湿（温度が３２．５℃、湿度が８５％）の環境下であっても、画像流れの発生は生じなかった。また、クリーニングブレードエッジ部にチッピングなどの問題は、発生しなかった。
【０１５８】
そして、感光体ドラム２自体も、３００万枚耐久後であっても、融着や、部分的なフィルミング層の発生や、摺擦傷などの、画像に発生するような問題は全く生じなかった。
【０１５９】
したがって、この第３の実施形態による画像形成装置においては、第１の実施形態におけると同様の効果を得ることができる。
【０１６０】
次に、上述した第１〜第３の実施形態における画像形成装置と比較するための、従来技術に基づいた比較例について説明する。
【０１６１】
（第１の比較例）
この第１の比較例による画像形成装置においては、第１の実施形態と異なり、感光体として、表層に２０μｍの膜厚のポリカーボネイトが設けられた従来のＯＰＣ感光体を用いる。そのほかの基本構成は、第１の実施形態におけると同様である。
【０１６２】
また、クリーニングの線圧としては、初期の段階で５５ｇ／ｃｍ（５３．９Ｎ／ｍ）必要であり、初期の表面粗さＲｚは、１．０であった。また、約１００００枚の耐久後に表面粗さＲｚが３．０μｍに達し、この段階からクリーニング不良が発生してしまった。
【０１６３】
（第２の比較例）
この第２の比較例による画像形成装置においては、第１の実施形態と異なり、現像スリーブの回転方向を感光体回転方向に対して、４００ｍｍ／ｓ（０．４ｍ／ｓ）の速さで順方向とする。そのほかの基本構成は、第１の実施形態におけると同様である。
【０１６４】
この第２の比較例において、本発明者が耐久検査行ったところ、３００００枚程度実行した後に画像流れが発生することが確認された。また、５００００枚程度実行した後に、クリーニング不良が発生したため、クリーニングブレードエッジを観察したところ、約３０〜５０μｍ程度の欠けが、数箇所に認められた。
【０１６５】
（第３の比較例）
この第３の比較例による画像形成装置においては、第１の実施形態と異なり、従来公知の粉砕法により製造されたトナーを用いる。なお、このトナーにおいて、その平均粒径や外添処方などは、第１の実施形態によるトナーと同様である。そのほかの基本構成は、第１の実施形態におけると同様である。
【０１６６】
この第３の比較例において、本発明者は、まず初期の段階で、クリーニングブレードのすり抜けとビビリ許容範囲とを検討した。その結果、許容範囲が、第１の実施形態によるアモルファスシリコン感光体に比して球形に近い重合トナーの許容範囲と比較して、明らかに少なくなったことが確認された。
【０１６７】
また、耐久検査を５００００枚程度行った後、クリーニングブレードのビビリが発生したことが確認された。そして、さらに耐久検査を続けたところ、所定時間が経過した後、クリーニングブレードめくれが発生してしまった。
【０１６８】
（第４の比較例）
この第４の比較例による画像形成装置においては、第１の実施形態と異なり、中間転写体を、ヤング率が１．０×１０^３ＭＰａで、引張強度が８０Ｎ／ｃｍのふっ化ビニリデン、２ふっ化ビニリデン（Ｐｏｌｙｖｉｎｙｌｉｄｅｎｅ　ｆｌｕｏｒｉｄｅ、ＰＶＤＦ）樹脂を用いる。そのほかの基本構成は、第１の実施形態におけると同様である。
【０１６９】
この第４の比較例において、本発明者が耐久検査を行ったところ、１０^５枚程度において、中間転写ベルト表面に周傷が発生し、さらにこの周傷部からのクリーニング不良や、フィルミング融着が発生したことが確認された。この不良発生の結果、感光体表面においても、フィルミング融着が転移していることが確認された。
【０１７０】
以上説明したように、この発明による第１から第３の実施形態による画像形成装置においては、画像流れの発生を防止するとともに、融着の発生を抑制可能な状態に、感光体表面を維持することができ、この表面状態をクリーニング部材等により、電子写真装置の信頼性を大きく向上させることができる。また、電子写真装置などの画像形成装置において、プロダクテビィティが大幅に飛躍した場合であっても対応することができる１ドラム回転現像器のフルカラー画像形成装置を得ることができる。
【０１７１】
以上、この発明の実施形態について具体的に説明したが、この発明は、上述の実施形態に限定されるものではなく、この発明の技術的思想に基づく各種の変形が可能である。
【０１７２】
例えば、上述の実施形態において挙げた数値、材料、混合比はあくまでも例に過ぎず、必要に応じてこれと異なる数値、材料、混合比を用いてもよい。
【０１７３】
なお、上述の実施形態においては、画像形成装置の構成例としてフルカラー複写機が挙げられているが、これに限定する趣旨ではなく、プリンタ、ファクシミリ、モノクロ複写機などの感光体ドラムを有する、あらゆる装置に適用することが可能である。
【０１７４】
【発明の効果】
以上説明したように、この発明によれば、像担持体と、感光体の外表面を帯電させる帯電手段と、感光体に光を照射する露光手段とを有し、帯電手段および露光手段により感光体の表面に形成された静電潜像に応じて、感光体表面にトナー像を形成する、少なくとも２種類以上の現像器を有する現像手段と、トナー像を中間転写体に接触転写する第一転写手段と、中間転写体上のトナー像を転写材に転写する第二転写手段と、感光体の表面に残留した残留トナーを除去するクリーニング手段とを有し、クリーニング手段が、少なくともクリーニングブレードおよび磁気ブラシから構成され、磁気ブラシに、１０重量パーセント以上の研磨粒子が拘束されているとともに、像担持体の表面が、クリーニング手段によるクリーニングが繰り返し実行されることにより感光体の表面の平均粗さが減少するように構成していることにより、画像流れの発生を抑制することができるとともに、融着の発生が抑制された感光体表面状態を維持することができ、電子写真装置に代表される画像形成装置の信頼性を大きく向上させることができ、将来にわたって画像形成装置のプロダクテビィティが飛躍的に向上した場合であっても、そのプロダクテビィティに対応することが可能になる。
【図面の簡単な説明】
【図１】この発明の第１の実施形態による画像形成装置を示す略線図である。
【符号の説明】
１　一次帯電器
２　感光体ドラム
３　現像装置
１０　原稿台ガラス
１１　露光光学系
１３　露光走査装置
３１　回転軸
３３ａ，３３ｂ，３３ｃ　現像器
３５ａ，３５ｂ，３５ｃ　現像ロール
３６ａ，３６ｂ，３６ｃ　規制ブレード
３７　現像スリーブ
４０　中間転写ベルト
４１　ベルト位置センサ
４２　一次転写ロール
４３　テンションロール
４４　二次転写用バックアップロール
４５　ベルト駆動ロール
４６　アイドラロール
４７　ベルトクリーナ
４８　二次転写ロール
５０　一成分磁性現像装置
５１　現像スリーブ
６０　給紙トレイ
６１　ピックアップロール
６２　レジロール
６３　シート搬送ベルト
６４　定着器
６４ａ　加熱ロール
６４ｂ　加圧ロール
６５　記録シート排出トレイ
７０　クリーニング装置
７１　クリーニング容器
７２　クリーニングブレード
７３　マグネットローラ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus, and in particular, is suitably applied to a full-color image forming apparatus of a one-drum rotary developing device type employing an electrophotographic method.
[0002]
[Prior art]
2. Description of the Related Art In recent years, multifunction peripherals that include output terminals such as a copier, a printer, and a facsimile and are compatible with a network have been widely accepted in the market.
[0003]
As an output terminal compatible with such a network, an electrophotographic system is widely accepted, but one of major problems is a duty cycle of the main body. The duty cycle is a limit number of sheets in which the main body can normally operate without maintenance by an operator.
[0004]
One of the biggest factors that limit the duty cycle is the life of the photosensitive drum. If the life of the photosensitive drum can be extended, waste can be reduced, that is, consumables can be reduced, consumables can have a long life, and reliability can be improved. And, from the viewpoint of environmental protection, development of such a technology is required.
[0005]
In addition, the shift from a conventional analog image forming apparatus to a digital image forming apparatus has progressed, and there is a keen desire to develop a technology for making the cost of the main body equivalent to or less than that of the analog type.
[0006]
Furthermore, in recent years, a conventional black-and-white machine, that is, a so-called monochrome machine, has been the mainstream in copiers and printers, but in offices, the use of originals or output files in full color has been rapidly increasing.
[0007]
For this reason, there is a demand for technical development that can realize not only a digital machine equivalent to the above-described analog type but also a full-color printer equivalent to a monochrome monochrome machine in terms of main body cost and running cost.
[0008]
In order to realize such a full-color printer equivalent to a black-and-white monochrome machine, there is a demand for the development of a technology capable of greatly reducing the necessary cost on the user side, so-called TCO.
[0009]
Under such circumstances, amorphous silicon (a-Si) photoconductors have been increasingly used as image carriers. This amorphous silicon photoreceptor has a Vickers hardness of 1000 or more (1000 kg / m ² As described above, it is very hard according to JIS standards and has excellent durability, heat resistance, and environmental stability. Therefore, it has become indispensable especially for high-speed machines that require high reliability.
[0010]
Further, this amorphous silicon photoconductor has an advantage that the number of replacement lifespan is one or more digits higher than that of a commonly used OPC photoconductor. That is, there is an advantage that waste can be reduced because the life of the main body is equivalent. Further, there is no need to require labor such as recovery and reproduction as in a process cartridge using an OPC photosensitive member.
[0011]
Therefore, if the present inventor can mount an image carrier using an amorphous silicon photosensitive member mounted on such a high-speed machine in a full-color printer, the duty cycle of the high-speed machine in black-and-white printing is considered. And improved running costs can be realized in the case of a color printer.
[0012]
In order to realize a high duty cycle (Duty Cycle) and a low running cost of a high-speed machine especially for a user having a high use ratio of black and white copy, the present inventor has proposed a one-drum type full-color printer using a rotary developing device. Then, it was recalled that it was necessary to mount an amorphous silicon photoconductor.
[0013]
However, according to the knowledge of the inventor, in these apparatuses, it is not limited to the toner that affects the image quality by adhering to the surface of the image carrier.
[0014]
That is, the factors that affect the image quality by adhering to the surface of the image carrier include fine paper powder generated from paper pieces often used as a transfer material, organic components precipitated therefrom, and high-pressure members in the apparatus. And corona products generated due to the presence of.
[0015]
Then, these fine paper powder, organic components, or corona products adhere to the surface of the image carrier and become foreign matters, and the resistance is reduced particularly in a high-humidity environment to form a clear electrostatic latent image. This is considered to be a factor causing image quality deterioration.
[0016]
It is known that the above-described image degradation phenomenon is likely to occur in the case of an amorphous silicon (amorphous silicon) photoconductor formed by film formation by glow discharge decomposition of silanes.
[0017]
Therefore, in order to avoid such a deterioration phenomenon in the amorphous silicon photoreceptor, especially when a one-component magnetic toner is used, along the running direction of the image carrier in the cleaning device, the upstream side of the cleaning blade. A method of disposing a magnet roller has been proposed.
[0018]
That is, a magnetic brush is formed by using a part of the toner collected by the cleaning device, and the magnetic brush is brought into contact with the surface of the image carrier to supply the magnetic toner again, so that the polishing action on the toner particles at the blade portion is achieved. There has been proposed a method of rubbing and removing the above-mentioned various foreign substances by utilizing the above.
[0019]
This technique not only reduces the local bias on the surface of the image carrier due to the polishing action, but also reduces the localization, as compared with a method of rubbing the surface of the image carrier using a separately prepared abrasive such as a web or a rubber roller. This has the advantage that deterioration of the surface of the image carrier can be suppressed.
[0020]
In addition, by using a heater in the image carrier and using ancillary means such as reducing the ambient humidity during standby and preventing the surface of the image carrier from having a low resistance during the standby time, There is a certain effect in preventing image deterioration due to the above-mentioned causes.
[0021]
Further, in an image forming apparatus in which the process of transferring a transferable toner image formed on the surface of an image carrier to a transfer material mainly using paper is repeated, the image carrier is not transferred to the transfer material during transfer. It is necessary to sufficiently remove the residual toner remaining on the body as needed.
[0022]
Therefore, various types of cleaning means have been conventionally proposed. A typical one of these means is to scrape off the residual toner using a cleaning blade made of an elastic material such as urethane rubber.
[0023]
The structure of the cleaning means using the cleaning blade is widely and practically used because it is not only simple and compact, but also low in cost, and has an excellent toner removing function.
[0024]
As a rubber material for the cleaning blade, generally, urethane rubber having high hardness, high elasticity, and excellent wear resistance, mechanical strength, oil resistance, and ozone resistance is used.
[0025]
[Problems to be solved by the invention]
However, these image forming apparatuses have six problems.
[0026]
That is, first, the amorphous silicon photosensitive member has a problem that the surface resistance is easily reduced. As described above, since the surface resistance of the amorphous silicon photoconductor is easily reduced, the magnetic brush is formed as described above, the magnetic brush is brought into contact with the surface of the image carrier, and the magnetic toner is resupplied. The device for rubbing and removing various foreign matters by using the polishing action of the toner particles is an effective means for magnetic toners, but is less effective for non-magnetic toners.
[0027]
Further, the following can be cited as factors that cause image deletion. In other words, fine paper powder generated from toner, paper used as a transfer material in most cases, organic components precipitated from this, various metal oxides and oxygen compounds during high-energy corona discharge generated from high-pressure members in the device Is a component that oxidizes nitrogen in the air to form nitrate ions with the occurrence of odor.
[0028]
When these foreign substances adhere to the surface of the image carrier, a thin film (hereinafter referred to as a filming layer) is formed on the surface of the photoreceptor by durable. Prevents the formation of an electrostatic latent image. These are factors that cause deterioration of image quality.
[0029]
In order to remove the filming layer due to such durability, it is necessary to improve the rubbing ability of the photoconductor surface. Specifically, when the elastic roll is brought into contact with the surface of the photoconductor at a different peripheral speed and rubbed, the toner locally adheres to the surface of the photoconductor. As a result, toner fusion occurs locally on the surface of the elastic roll, and this portion scrapes the surface of the photoreceptor, and further causes uneven shaving, which causes image defects.
[0030]
In order to avoid such image defects, it is necessary to further improve the slidability of the surface of the photoreceptor by the elastic roll. However, according to the knowledge of the present inventor, even if the image carrier is made of amorphous silicon, if the rubbing property is improved, the amount of abrasion sharply increases, and the reliability thereof decreases. .
[0031]
Further, in the above-described setting, there is a problem that the wear amount of the elastic roll itself is increased and the reliability is reduced.
[0032]
In addition, the inventor conducted an experiment on the filming layer formed by the above-mentioned durability by an optical method, and it was confirmed that the film thickness was about 3 to 8 nm.
[0033]
That is, when the present inventor measured the image carrier using a reflection spectroscopy interferometer (for example, MCDP2000 manufactured by Otsuka Electronics Co., Ltd.), the filming layer was formed on the above-described surface oxide layer even in the early stage of durability. confirmed. This filming layer reached about 3 to 8 nm, and it was confirmed that the film thickness hardly changed after this film thickness was formed.
[0034]
However, the present inventor has conducted experiments, and it has been found that as the endurance progresses, the image degradation that has been eliminated by dry wiping, water wiping, alcohol wiping, or the like in the initial stage is not eliminated.
[0035]
Then, the adhesive wear by the inventor was repeatedly performed, and the cerium oxide (CeO) having a particle size of about 0.3 to 2 μm was applied to the surface of the drum which had been durable in this state. ₂ It was found that the image deterioration would not be eliminated unless the abrasive grains composed of (1) and (2) were polished using an abrasive dispersed in alcohol or the like.
[0036]
Such a problem occurs remarkably especially when the drum heater is not mounted. Therefore, the inventor has further studied diligently to convert the surface of the initial photoconductor of various surface shapes and the surface of the photoconductor after durability into NANOScopeIIIA Dimension 3000, manufactured by Atomic Force Microscopy (AFM: Digital Instruments). (Scanning mode: tapping mode, scanning range: 20 μm × 20 μm, probe: Si cantilever).
[0037]
In the measurement by the present inventor, the surface of the photoreceptor after the endurance is almost smoother in appearance due to abrasion compared to the initial stage. Therefore, the surface of the photoreceptor after the endurance is treated with 5% sodium peroxodisulfate (Na ₂ S ₂ O ₈ ) In an aqueous solution, heated at a temperature of 70 to 80 ° C. for 30 minutes, ultrasonically cleaned in acetone for about 1 minute, rinsed with ethanol and pure water, and observed. It was confirmed that the filming amount was large.
[0038]
Second, the present inventor has conducted further experiments and found that the frictional force between the transfer residual toner and the drum by the cleaning blade has increased due to the durability as described above.
[0039]
In this regard, the present inventors have further studied and have come to recall that this increase in frictional force is caused by the filming layer formed by durability.
[0040]
That is, the adhesion and affinity between the cleaning blade and the drum surface and between the transfer residual toner and the drum surface are increased by the filming layer formed by durability, and as a result, the frictional force is increased. I came to remember that.
[0041]
It is considered that the increase in the frictional force increases the shear stress of the cleaning blade, the shear stress between the toners, and the shear stress near the drum surface. As a result of the increase in these shearing stresses, local edge chipping of the cleaning blade, so-called chipping, toner and fusion occur due to an increase in heat generation due to an increase in permanent strain shearing stress, and an increase in fatigue wear due to an increase in internal stress of the drum. It is thought to have led to the outbreak.
[0042]
Thirdly, in recent years, as described above, in the image forming apparatuses, those having a function as a printer as well as a copying machine have been widely used.
[0043]
Furthermore, applications such as a feeder function and a sorter function have been enhanced, and continuous operation of 4000 or more jobs at one time has become possible. For example, even when the A4 paper is output at 50 sheets / minute, the continuous operation is performed for 80 minutes or more by a simple trial calculation.
[0044]
Under such a situation, the ambient temperature near the photoconductor reaches around 50 ° C. It is considered that the temperature at the contact (nip) between the cleaning blade and the photoconductor has reached 50 ° C. or higher. As a result, the frequency at which toner fusion occurs on the surface of the photoconductor increases.
[0045]
Fourth, a full-color toner is generally a non-magnetic material. For this reason, the magnetic brush cleaning method often used in black-and-white machines conventionally requires a magnetic carrier to be held in a cleaner unit in advance. In this case, problems occur in reliability and durability, respectively.
[0046]
Fifth, use of spherical toner can be mentioned. More specifically, in recent years, polymerized toners have been increasingly used because the transfer efficiency is improved and a releasing material for fixing is not required.
[0047]
However, toner produced by a polymerization method generally has a high sphericity. In the case where the sphericity of the toner is high as described above, in the conventional counter blade system generally used, the amount of toner slipping through increases. Further, the transfer efficiency can be maintained at 97% or more, and the probability of the presence of a toner exhibiting a lubricating function between the cleaning blade and the photosensitive drum is extremely small.
[0048]
For these reasons, when the above-described filming layer is formed, a local shearing force is applied to the cleaning blade, so that edge chipping occurs.
[0049]
Accordingly, the present inventors have conducted intensive studies on this problem. As a result, the a-Si photoreceptor having a high surface hardness and a smooth surface has a high sphericity, and the toner manufactured by a polymerization method has a high surface hardness. It has been found that the cleaning property is extremely good as compared with the OPC photosensitive member having relatively low hardness and easily rubbing the surface.
[0050]
However, on the other hand, it was confirmed that when the filming layer was formed as described above, a local shearing force was exerted on the cleaning blade and edge chipping occurred.
[0051]
Sixth, when the intermediate transfer belt is used, if the surface of the intermediate transfer belt deteriorates early, peripheral scratches and fusion of the surface of the intermediate transfer belt may occur via the contact portion of the primary transfer portion. It is transferred to the surface of the photoreceptor, which is one of the causes of lowering the reliability of the surface of the photoreceptor.
[0052]
Therefore, an object of the present invention is to provide a cleaning member that can prevent the occurrence of image deletion even when using a non-magnetic toner and can maintain the surface state of a photoconductor without fusing, thereby using an electronic member. To provide an image forming apparatus such as an electrophotographic apparatus capable of dramatically improving the reliability of the image forming apparatus such as a photographic apparatus and coping with a breakthrough in productivity of the electrophotographic apparatus. It is in.
[0053]
[Means for Solving the Problems]
In order to solve the problems described above, the present invention
A first image carrier, charging means for charging an outer surface of the first image carrier, and exposing means for irradiating the first image carrier with light; Developing means for forming a toner image on the surface of the first image carrier according to the electrostatic latent image formed on the surface of the first image carrier by means;
Transfer means for transferring the toner image to a second image carrier;
Cleaning means for removing residual toner remaining on the surface of the first image carrier;
The cleaning means comprises at least a cleaning blade and a magnetic brush,
10% by weight or more of abrasive particles are constrained by the magnetic brush, and the surface of the first image carrier is repeatedly cleaned by the cleaning means so that the first image carrier is cleaned. Configured to reduce average surface roughness
It is characterized by the following.
[0054]
In the present invention, the average roughness is typically a ten-point average roughness, but the same effect can be obtained with other average roughnesses.
[0055]
In the present invention, typically, the image forming apparatus further includes a static eliminator for removing a residual electrostatic latent image.
[0056]
In the present invention, typically, the second image bearing member is an intermediate transfer member, and the intermediate transfer member is formed of a resin belt, and the resin belt has a Young's modulus of 2.5 × 10 ³ MPa or higher and a tensile strength of 10 ⁵ N / m (1000 N / cm) or more.
[0057]
In the present invention, typically, the first image carrier is formed of an amorphous silicon (a-Si) based photoconductor. In the present invention, preferably, at least the surface of the first image carrier is made of hydrogenated amorphous carbon. In the present invention, typically, the first image bearing member is a photoreceptor, preferably an electrophotographic photoreceptor.
[0058]
In the present invention, typically, the toner is substantially spherical, and the developing sleeve of the developing device is rotatable in the counter direction with respect to the first image carrier, and rubs the surface of the first image carrier. This is a two-component magnetic brush developing system that is configured as possible. In the present invention, preferably, the toner is a non-magnetic toner, and the average particle diameter of the toner is 6 μm or more and 10 μm or less. The toner preferably has at least a toner produced by a polymerization method having a shape factor SF-1 of 100 or more and 140 or less and a shape factor SF-2 of 100 or more and 120 or less.
[0059]
In the present invention, typically, at least abrasive particles having a Mohs' hardness of at least 6 are externally added in a range of 0.01% by weight or more and 5.0% by weight or less based on the toner base, and The average particle size is 0.5 μm or more and 3.0 μm or less.
[0060]
The present invention includes all combinations of the technical ideas of the invention described above, and the technical ideas described above can be appropriately combined.
[0061]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals.
[0062]
First, an image forming apparatus according to a first embodiment of the present invention will be described. FIG. 1 shows an image forming apparatus according to the first embodiment.
[0063]
(1st Embodiment)
As shown in FIG. 1, in the image forming apparatus according to the first embodiment, a document (not shown) placed on a document table glass 10 is irradiated with light, and the reflected light is applied to an exposure optical system. Through 11, the light reaches a solid-state imaging device (CCD) 12.
[0064]
The CCD 12 converts the reflected light into R (red), G (green), and B (blue) electric signals, respectively. The image processing system (IPS) converts the above-described RGB electrical signals input from the CCD 12 into K (black), Y (yellow), M (magenta), and C (cyan) image data and temporarily stores the converted data. Remember. The above-mentioned image data is output to a laser driving circuit (not shown) as latent image forming image data at a predetermined timing.
[0065]
The laser drive circuit supplied with the image data outputs a laser drive signal (not shown) to the latent image writing device (ROS) according to the supplied image data.
[0066]
On the other hand, the photosensitive drum 2 as the first image carrier rotates in the direction of arrow Da in FIG. Further, after the surface of the photosensitive drum 2 is uniformly charged by the primary charger 1 as charging means, at the latent image writing position A, the above-described latent image writing device (ROS) as exposure means is used. Exposure scanning is performed with a laser beam L (main wavelength: 655 nm). As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 2.
[0067]
On the other hand, when forming a full-color image, electrostatic latent images corresponding to four color images of K (black), Y (yellow), M (magenta), and C (cyan) are sequentially formed. In the case of a monochrome image, only an electrostatic latent image corresponding to a K (black) image is formed.
[0068]
In the above-described latent image writing on the surface of the image carrier with the laser beam L, the belt position sensor 41 detects a home position provided on a non-image portion of the intermediate transfer belt 40 as an intermediate transfer body made of a resin belt. Then, after a predetermined period of time, the process is started.
[0069]
Specifically, in the case of a full-color image, since the respective colors are superimposed and formed, the time from when the belt position sensor 41 detects the home position to when the latent image writing by the laser beam L is started is as follows. Same for each color.
[0070]
Next, the surface of the photosensitive drum 2 on which the electrostatic latent image has been formed is rotated and sequentially passes through the developing area B and the primary transfer area C. Further, in the rotary developing device 3, developing devices 33 a and 33 b of three colors of Y (yellow), M (magenta), and C (cyan) that sequentially rotate and move the developing area B with the rotation of the rotating shaft 31. , 33c are further provided.
[0071]
These developing units 33a, 33b, and 33c are provided with developing rolls 35a, 35b, and 35c, respectively, for transporting the developer to the above-described developing area B, and are provided on the surface of the photosensitive drum 2 that passes through the developing area B. The electrostatic latent image is a toner image. Here, a developing process of using the electrostatic latent image as a toner image will be described.
[0072]
That is, the regulating blades 36a, 36b and 36c arranged to form a thin layer of the developer on the surface of the developing sleeve are developing containers. The developing rolls 35a, 35b, 35c are arranged so that the area closest to the photosensitive drum 2 is about 400 μm at least at the time of development. Further, the developer is set to be developable in a state where the developer contacts the photosensitive drum 2.
[0073]
The two-component developer used in the first embodiment has an average particle diameter of a negatively charged toner having a mean particle diameter of 6 to 10 μm, for example, 7 μm, which is produced by a polymerization method. What added 20% of titanium oxide by weight ratio 1% is used. The carrier has a saturation magnetization of 2.05 × 10 ⁵ A / m (205 emu / cm ³ ), A magnetic carrier having an average particle size of 35 μm was used. In addition, a mixture of the toner and the carrier at a weight ratio of 6:94 was used as a developer.
[0074]
Here, a developing process for visualizing an electrostatic latent image by a two-component magnetic brush method using the developing device 3 and a circulation system of the developer will be described.
[0075]
First, the developer pumped up by the N2 pole with the rotation of the developing rolls 35a, 35b, 35c is arranged perpendicular to the developing rolls 35a, 35b, 35c in the process of being transported from the S2 pole to the N1 pole. It is regulated by regulating blades 36a, 36b, 36c. Thereby, a thin layer is formed on the developing rolls 35a, 35b, and 35c.
[0076]
Here, when the developer formed as a thin layer is conveyed to the developing main pole S1, a spike shape is formed by the magnetic force. The electrostatic latent image is developed by the spike-shaped developer, and then the developer on the developing rolls 35a, 35b, and 35c is returned into the developing container by the repulsive magnetic fields of the N3 pole and the N2 pole. It is.
[0077]
A DC voltage and an AC voltage are applied to the developing rolls 35a, 35b, and 35c from a power supply (not shown). In the first embodiment, the surface potential V _d + 450V, V _l With respect to + 50V, DC voltage is + 300V, AC voltage is Vpp = 1500V, Vf = 2000s ^-1 Is applied.
[0078]
In general, in the two-component developing method, when an AC voltage is applied, the developing efficiency is increased, and the quality of an image is high. On the contrary, a problem that “fog” easily occurs is also caused. Therefore, normally, by providing a potential difference between the DC voltage applied to the developing device 3 and the surface potential of the photosensitive drum 2, it is possible to prevent the occurrence of "fog".
[0079]
The developing sleeve 37 is disposed at a peripheral speed of 450 mm / s in the counter direction with respect to a peripheral speed of the photosensitive member of 300 mm / s. The rotational load torque of the developing rolls 35a, 35b, 35c on the photoreceptor surface is 3.7 × 10 ^-2 N · m (0.38 kgf · cm). The rotational load torque as a function of rubbing against the photoreceptor on the developing sleeve by a magnetic brush is 1.96 × 10 ^-2 ~ 5.88 × 10 ^-2 N · m (0.2 to 0.6 kgf · cm) is preferred.
[0080]
Next, the non-magnetic toner will be described. First, a mixture of a polymerized toner produced by a suspension polymerization method and a resin magnetic carrier produced by a polymerization method was used as a two-component developer. The T / D ratio of the obtained developer was 8%.
[0081]
As a magnetic carrier, the specific resistance is 10 ¹³ Ω · cm was used. The non-magnetic polymerized toner is a substantially spherical toner having a smooth surface with a shape factor SF-1 of 115 and SF-2 of 110, a weight average particle diameter of 8 μm, and a specific gravity of 1. 05g / cm ³ The toner having an average charge per unit mass of 25 μC / g was used.
[0082]
As the polymerized toner used in the present invention, an approximately spherical toner having a shape factor SF-1 in the range of 100 to 140 and SF-2 in the range of 100 to 120 is preferable in order to maintain high transfer efficiency.
[0083]
In the first embodiment, the shape factors SF-1 and SF-2 are determined using a scanning electron microscope (for example, FE-SEM (S-800) manufactured by Hitachi, Ltd.), and 100 toner particles are randomly determined. , And the image information is introduced into an image analysis device (for example, Luzex3, manufactured by Nireco Co., Ltd.) via an interface to perform analysis.
[0084]
The values calculated by the following equations were defined as shape factors SF-1 and SF-2.
(Equation 1)

[0085]
By using such a spherical toner, it is possible to always ensure the primary transfer efficiency of 95% or more. Further, in the first embodiment, since the Mohs hardness of the SiC layer on the surface of the photoreceptor is about 8, fine particles having a Mohs hardness of 9 as an external additive, specifically, an average particle diameter of 1.2 μm are used. Alumina (Al ₂ O ₃ ) Was added by 1% by weight.
[0086]
Next, the one-component developer for monochrome will be described. That is, in the first embodiment, a magnetic toner for monochrome was manufactured using the following raw materials.
Resin obtained by mixing polyester resin and vinyl copolymer: 100 parts by weight
Magnetic iron oxide: 90 parts by weight (Si content: 1.5% by weight, average particle size: 0.2 μm, Hc: 9.5 kA / m, σs: 65 m) ² / Kg, σr: 7 Am ² / Kg)
Organic zirconium compound: 2 parts by weight
Paraffin wax: 5 parts by weight
Strontium titanate fine powder: 4.0 parts by weight
[0087]
Then, after the above-mentioned materials were pre-mixed by a Henschel mixer, they were melt-kneaded by a twin-screw kneading extruder (for example, PCM-30, manufactured by Ikegai Iron Works) set at a temperature of 130 ° C.
[0088]
Thereafter, the obtained kneaded material was cooled, coarsely pulverized by a cutter mill, and then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was subjected to a multi-divided classifier utilizing the Coanda effect. To obtain a magnetic toner having a weight average particle size of 7.5 μm.
[0089]
In the obtained magnetic toner, the ratio of the fine powder toner having a volume average particle size of 4 μm or less is 20% or less and the ratio of the coarse powder toner having a volume average particle size of 15 μm or more is related to the toner having a volume average particle size of 7 μm. It was less than 5%.
[0090]
As the abrasive particles, diamond (Mohs hardness (the same applies hereinafter): 15), boron carbide (14), silicon carbide (13), titanium carbide (13), aluminum oxide (12), sapphire (12), ruby (12) And particles having a high Mohs hardness, such as Corundum (12).
[0091]
Further, the size of the abrasive particles is determined so that abrasion marks do not enter when polishing the surface of the photoreceptor drum 2 and the surface becomes a mirror surface. Specifically, the upper limit of the size of the abrasive grains is set such that the size of the scratch mark is sufficiently smaller than the image recognition size of several tens of μm. According to this setting, the abrasive grain size is preferably # 800 or more according to the standard of JIS-R-6001.
[0092]
As shown in FIG. 1, the one-component magnetic developing device 50 as a part of the developing means for the black toner contains, for example, negative toner having the same polarity as the photosensitive drum 2. The magnetic force of the magnet is equal to the magnetic pole N on the surface of the developing sleeve 51. ₁ : 86mT (860 gauss), magnetic pole S ₁ : 95mT (950 gauss), magnetic pole N ₂ : 75mT (750 gauss), magnetic pole S ₂ : 66 mT (660 gauss) is adopted.
[0093]
In addition, the magnetic pole S responsible for one of the developing processes ₁ Are arranged to face the photosensitive drum 2 via the developing sleeve 51. Magnetic pole N responsible for regulation of the other toner layer ₁ Are arranged to face the regulating blade via the developing sleeve 51.
[0094]
In the first embodiment, it is desirable that the closest distance between one developing sleeve 51 and the photosensitive drum 2 is 150 to 300 μm. On the other hand, the gap between the developing sleeve 51 and the regulating blade is desirably 150 to 300 μm.
[0095]
Further, the peripheral speed of the developing sleeve 51 is desirably set to about 120 to 190% of the peripheral speed of the photosensitive drum 2.
[0096]
The developing bias applied to the developing sleeve 51 from a power supply (not shown) includes a peak-to-peak voltage Vpp = 1.0 to 2.0 kV and a frequency f = 1.0 to 2.0 ks. ^-1 And a bias in which a DC voltage of 100 to 400 V is superimposed on an AC voltage of Duty = 20 to 50%.
[0097]
Note that the K toner is preferably a magnetic toner as described above. The magnetic toner has 100 parts by weight of a binder resin having a glass transition temperature of 40 to 60 ° C., and at least 0.2 to 20 parts by weight of a solid wax and 10 to 200 parts by weight of a magnetic substance. It is composed.
[0098]
Examples of the binder resin having a glass transition temperature of 40 to 60 ° C. include phenol resins and polyesters such as styrene-based styrene-acryl copolymers and styrene-butadiene copolymers.
[0099]
The glass transition temperature (Tg) is measured using a differential scanning calorimeter (DSC measuring apparatus) (for example, DSC-7 manufactured by PerkinElmer) in accordance with ASTM D3418-82. is there.
[0100]
Specifically, 5 mg of the measurement sample is precisely weighed and placed in an aluminum pan, and measurement is performed using an empty aluminum pan as a reference at a temperature rising rate of 10 ° C./min while setting the temperature range to 30 to 200 ° C. In this heating process, an endothermic peak of a main peak is obtained in a DSC curve in a temperature range of 40 to 100 ° C.
[0101]
The intersection of the DSC curve with the line at the midpoint of the baseline before and after the endothermic peak appears at this time is defined as the glass transition temperature (Tg). In the first embodiment, the magnetic toner preferably has an average particle diameter of 6 to 10 μm, and more preferably 6 to 8 μm.
[0102]
Further, in the magnetic toner according to the first embodiment, with respect to the toner having a volume average particle diameter of 7 μm, the ratio of the fine powder toner having a volume average particle diameter of 4 μm or less is 20% or less, and the volume average particle diameter is 15 μm or more. Is preferably 5% or less.
[0103]
Below the surface of the photosensitive drum 2 as the above-described first image carrier, an intermediate transfer belt 40 as an intermediate transfer body as a second image carrier, a belt driving roll 45, a tension roll 43, an idler A plurality of belt support rolls including a roll 46 and a secondary transfer backup roll 44, a primary transfer roll 42 as a first transfer unit, and a belt frame (not shown) that supports them are provided. The intermediate transfer belt 40 is rotatably supported by the above-described belt support roll.
[0104]
Then, when forming a full-color image, a first-color electrostatic latent image is formed at the latent-image writing position A, and a first-color toner image is formed at the developing region B. When the toner image passes through the primary transfer area D, the primary transfer is electrostatically primary-transferred onto the intermediate transfer belt 40 by the primary transfer roll 42.
[0105]
Thereafter, similarly, the second color, third color, and fourth color toner images are sequentially superimposed on the intermediate transfer belt 40 carrying the first color toner image, and primary transfer is performed. Finally, a full-color multiple toner image is formed on the intermediate transfer belt 40.
[0106]
In the case of forming a monochrome monochrome image, only the one-component magnetic developing device 50 is used, and the monochrome toner image is primarily transferred onto the intermediate transfer belt 40.
[0107]
After the primary transfer, the residual toner on the surface of the photosensitive drum 2 is cleaned by the cleaning device 70.
[0108]
The recording sheet S stored in the paper feed tray 60 is taken out by the pickup roll 61 at a predetermined timing, and is conveyed to the registration roll 62.
[0109]
The recording sheet S conveyed by the registration roll 62 is conveyed to the secondary transfer area at the timing when the primary-transferred multi-toner image or single-color toner image moves to the secondary transfer area E. .
[0110]
Thereafter, in the secondary transfer area E, the secondary transfer roll 48 as the second transfer unit electrostatically and secondarily collectively electrostatically transfers the toner image on the intermediate transfer belt 40 to the recording sheet S. After the secondary transfer, the residual toner remaining here is removed from the intermediate transfer belt 40 by the belt cleaner 47.
[0111]
The above-described secondary transfer roll 48 and the belt cleaner 47 are disposed so as to be freely separated from and contactable with the intermediate transfer belt 40. When a color image is formed, the unfixed toner image of the final color is separated from the intermediate transfer belt 40 until it is primarily transferred to the intermediate transfer belt 40.
[0112]
The recording sheet S on which the toner image is secondarily transferred is conveyed by a sheet conveying belt 63 to a fixing device 64 having a pair of fixing rolls composed of a heating roll 64a and a pressure roll 64b, and is heated and fixed. The recording sheet S on which the toner image is fixed is discharged from the recording sheet discharge tray 65 to the outside of the apparatus.
[0113]
The intermediate transfer belt 40 has a two-layer structure of a polyimide layer and a cyanoresin layer (high dielectric constant layer). The intermediate transfer belt 40 is manufactured as follows.
[0114]
That is, the thermosetting seamless belt in which the carbon black of the base layer is dispersed is formed by mixing carbon black with a polyimide varnish U for heat-resistant film (manufactured by Ube Industries, Ltd.) and mixing with a mixer or the like. Then, after injecting this stock solution into a cylindrical mold, centrifugal molding is performed while heating.
[0115]
Subsequently, the mold is released in a semi-cured state, the removed belt is covered with an iron core, and heated at a temperature of 400 ° C. to 450 ° C., whereby the main curing is performed by an imidization reaction. Thereby, the surface resistivity becomes 10 ¹² Ω / □, volume resistivity is 10 ¹⁰ A seamless belt having a thickness of 75 μm and a thickness of Ωcm is manufactured.
[0116]
Here, the intermediate transfer belt 40 used in the image forming apparatus according to the first embodiment has a Young's modulus of 2.5 × 10 ³ MPa or higher, tensile strength 1.0 × 10 ⁵ It is preferably N / m (1000 N / cm) or more, and a resin such as polyimide having high Young's modulus and high tensile strength is preferable.
[0117]
On the other hand, the layer configuration of the backup roll 44 for secondary transfer, which is a support roll for the intermediate transfer belt 40 and also serves as a counter electrode of the secondary transfer roll 48, may have a single-layer structure or a multilayer structure.
[0118]
Specifically, when the layer configuration is, for example, a single layer structure, the secondary transfer backup roll 44 is formed by mixing an appropriate amount of conductive fine powder such as carbon black with silicone rubber, urethane rubber, ethylene propylene diene monomer (EPDM), or the like. Consists of rolls that have been created.
[0119]
The secondary transfer backup roll 44 in the case of the two-layer structure is composed of a core layer and a skin layer.
[0120]
Of these, the core layer is made of a foam such as silicone rubber, urethane rubber or ethylene propylene diene monomer (EPDM) whose volume resistivity is appropriately adjusted.
[0121]
The skin layer is formed by blending a conductive agent such as carbon black with conductive silicone rubber, urethane rubber, or ethylene propylene diene monomer (EPDM), and is provided on the outer peripheral surface of the core layer.
[0122]
The volume resistivity of the secondary transfer backup roll 44 according to the first embodiment is 10 ⁷ -10 ⁹ It is preferably in the range of Ω · cm.
[0123]
Further, the above-described secondary transfer roll 48 can employ various film configurations, and is not particularly limited. In the first embodiment, for example, in the case of a two-layer structure, a structure including a core layer and a coating layer covering the surface of the core layer is used.
[0124]
Among these, the core layer is made of silicone rubber, urethane rubber or ethylene propylene diene monomer (EPDM) in which conductive powder is dispersed, or is made of a foam thereof.
[0125]
On the other hand, the coating layer is preferably made of a fluororesin-based material in which conductive powder is dispersed. Examples of the fluororesin include tetrafluoroethylene (TFE), hexafluoropropylene copolymer (FEP), and perfluoroalkoxy resin (PFA). The volume resistivity of the secondary transfer roll 48 is 10 ⁶ -10 ⁹ It is preferably in the range of Ω · cm.
[0126]
Further, the maximum image width of the electrophotographic copying machine according to the first embodiment is about 320 mm for A4 width and noble, and the drum peripheral speed is 300 mm / s.
[0127]
The photosensitive drum 2 is composed of an amorphous silicon-based photosensitive member, specifically, a photosensitive member having a photosensitive layer formed of a non-single-crystal material (amorphous silicon, a-Si) having silicon atoms as a base. Is done. Amorphous silicon (a-Si) includes atoms classified into Group 3B of the periodic table, such as hydrogen atom, halogen atom, carbon atom, oxygen atom, and boron, and so-called periodic table such as nitrogen (N). Those containing other atoms, such as those classified in 5B, are also possible.
[0128]
The photosensitive layer is preferably a laminated film in which a plurality of layers having different functions are laminated. Examples of such a laminated film include a photoconductive layer, a buffer layer, a surface layer, and the like, which include a lower blocking layer, a charge transport layer, or a charge generation layer.
[0129]
Further, from the viewpoint of improving the hardness of the photoconductor surface and improving the lubricity of the photoconductor surface, the amorphous silicon-based photoconductor has a surface layer made of hydrogenated amorphous carbon on the outermost surface. More preferred.
[0130]
This hydrogenated amorphous carbon has a configuration (a-C: H) in which a hydrogen atom is contained in a non-single-crystal material having a carbon atom as a base material, and has another structure similar to the above-mentioned amorphous silicon (a-Si). Those containing atoms are also possible. Note that “aC: H” mainly represents amorphous carbon having an intermediate property between graphite and diamond, but may partially include microcrystals or polycrystals.
[0131]
Further, the amorphous silicon-based photoconductor having the surface layer formed thereon can be manufactured by a conventionally known method. That is, as a method of manufacturing the amorphous silicon-based photoconductor, for example, a plasma chemical vapor deposition method (plasma CVD method) or the like can be used.
[0132]
In this plasma CVD method, first, a conductive substrate is placed in a system, and an atom supply gas (source gas) containing the above-described atoms is introduced into the system. Thereafter, in the system, the source gas is decomposed by generating plasma. Then, this is a method in which atoms of the decomposed raw material gas are reacted and vapor-phase grown on the conductive substrate.
[0133]
The thickness and strength of the photosensitive layer including the surface layer formed by the plasma CVD method can be adjusted by the concentration of the raw material gas and the high-frequency power used for discharging. Here, as the raw material gas, a mixed gas of hydrogen and an inert gas (a rare gas or a nitrogen gas) can be used.
[0134]
The photoconductor drum 2 is configured to include a positively charged amorphous silicon photoconductor. As an example of the dimensions of the photosensitive drum 2 having this photosensitive member, an amorphous silicon photosensitive layer having a thickness of, for example, 30 μm is formed on an aluminum cylinder surface having a diameter of 80 mm and a thickness of about 3 mm by, for example, glow discharge. Is formed. As the surface layer of the photosensitive drum 2, a hydrogenated silicon carbide (SiC: H) film having a thickness of, for example, 800 nm was used.
[0135]
Next, the cleaning device 70 as a cleaning unit will be described. That is, the cleaning container 71 of the cleaning device 70 holds the cleaning blade 72 abutting on the surface of the photosensitive drum 2 described above.
[0136]
The cleaning blade 72 is an elastic blade mainly composed of urethane according to JIS, and has a Mohs hardness of 70 degrees (Hs), a rebound resilience of 15% (25% resilience at 40 ° C.), and a 300% modulus of 200 kg. / Cm ² It is composed of the following materials. The cleaning blade 72 has a plate thickness of, for example, 2 mm, and a member of, for example, 20 cSUS (plate thickness: 1.0 mm) is provided as a back plate.
[0137]
The cleaning blade 72 is disposed on the photosensitive drum 2 at a contact angle of 24 ° and a contact pressure of 19.6 N / m (20 g / cm). The free length of the cleaning blade 72 is, for example, 3 mm.
[0138]
Further, a magnet roller 73 is provided on the upstream side of the above-described cleaning blade 72 in the cleaning container 71, that is, on the upstream side in the rotation direction of the photosensitive drum 2, as a magnetic material holding means. The magnet roller 73 is provided at a predetermined distance from the photosensitive drum 2 in the direction perpendicular to the paper of FIG.
[0139]
A magnetic brush is formed on the surface of the magnet roller 73 by collecting magnetic toner by a magnetic field (8 poles, 100 mT (1000 gauss)). The magnet roller 73 is configured to be capable of rubbing the surface of the photoconductor by rotating at a peripheral speed of 10% relative speed in a forward direction with respect to the rotation direction of the photoconductor drum 2.
[0140]
In the exposure scanning device 13, a light emitting diode mainly composed of, for example, an AlGaAs compound element having a peak wavelength of 660 nm is used. This light emitting diode has a half width at which it becomes １ ／ of its peak wavelength, for example, about 25 nm, and an exposure amount is, for example, 20 μJ / cm. ² It is.
[0141]
The travel time of the photoconductor surface from the pre-exposure by the exposure scanning device 13 to the primary charger 1 is, for example, about 50 mm / s.
[0142]
As described above, the photosensitive drum 2 is provided with an amorphous silicon photosensitive layer having a thickness of 30 μm by glow discharge or the like on an aluminum cylinder having a diameter of 80 mm and a thickness of about 3 mm. Further, as the surface layer of the photosensitive drum 2, a layer obtained by laminating, for example, 800 nm thick SiC: H is used. The Vickers hardness is, for example, 1100 kg / mm ² It is.
[0143]
The inventor conducted a durability test using the photosensitive drum 2 having the above-described amorphous silicon-based photosensitive member in a high-temperature and high-humidity environment (temperature of 32.5 ° C., humidity of 85%). . As a result, no image deletion occurred even after the endurance of 3 million sheets. Furthermore, no chipping or the like was observed at the edge of the cleaning blade.
[0144]
The photosensitive drum 2 itself did not have any problems such as fusion, partial filming layer generation, and rubbing scratches even after the endurance of 3 million sheets.
[0145]
Further, the initial surface roughness Rz of the photosensitive drum 2 was 0.36 μm (AFM described above: the search range of 20 μm × 20 μm), whereas the surface roughness Rz of 3 million sheets of the photosensitive member after the durability test was performed. Was 0.08 μm.
[0146]
Abrasive particles made of, for example, alumina / strontium titanate, which were bound by the magnetic brush on the magnet roller of the cleaning device, accounted for 16% by weight. The amount of wear was about 0.12 nm per 1000 rotations.
[0147]
In addition, 5% sodium peroxodisulfate (Na ₂ S ₂ O ₈ ) After heating in an aqueous solution at a temperature of 70 ° C to 80 ° C for 30 minutes, ultrasonic cleaning (about 1 minute) in acetone, reflection spectroscopy interferometer before and after rinsing with ethanol / pure water (Otsuka Electronics Co., Ltd.) When the film thickness was measured using MCDP2000, no filming layer was confirmed.
[0148]
(Second embodiment)
Next, an image forming apparatus according to a second embodiment of the present invention will be described. In the image forming apparatus according to the second embodiment, unlike the first embodiment, a black toner obtained by externally adding 3.0% by weight of Si—C having an average particle diameter of 1.5 μm is used. The other basic configuration is the same as that in the first embodiment, and thus the description is omitted. The abrasive particles (alumina / Si-C) bound by the magnetic brush on the magnet roller in the cleaning device were 12% by weight.
[0149]
In the second embodiment, even in a high-temperature, high-humidity (temperature of 32.5 ° C., humidity of 85%) environment, even after performing a durability test of 3 million sheets, the occurrence of image deletion does not occur. Did not occur. Also, no problem such as chipping occurred at the edge of the cleaning blade.
[0150]
Also, in the case of the photosensitive drum 2, even after the endurance of 3 million sheets, no problems such as fusion, partial generation of a filming layer, and scratches on the image occurred at all. Further, the surface roughness Rz after the endurance of 3 million sheets was smaller than that before the endurance test, and was 0.15 μm.
[0151]
According to the image forming apparatus according to the second embodiment, the same effects as in the first embodiment can be obtained.
[0152]
(Third embodiment)
Next, an image forming apparatus according to a third embodiment of the present invention will be described. In the image forming apparatus according to the third embodiment, the floor is the same as that of the first embodiment, and a photoconductor in which aC: H (hydrogenated amorphous carbon) is laminated to a thickness of 100 nm on a surface layer is used. The other basic configuration is the same as in the first embodiment, and a description thereof will not be repeated. Further, according to the experiments of the present inventor and the accompanying study, hydrogenated amorphous carbon (aC: H) has a coefficient of friction lower than that of the surface layer composed of SiC: H used in the second embodiment. Has been confirmed to be small.
[0153]
According to an experiment by the present inventors, image deletion occurs even after a durability test of 3 million sheets in a high-temperature and high-humidity (temperature of 32.5 ° C., humidity of 85%) environment. Not confirmed.
[0154]
Further, with respect to the photosensitive drum 2 itself, even after the durability test of 3 million sheets, problems such as fusion, partial filming layer generation, cleaning failure, scratches and the like, which occur in the image, are completely eliminated. Did not occur. The amount of wear at that time was 0.02 nm per 1,000 rotations.
[0155]
It was also confirmed that the coefficient of friction after durability was maintained at a low value. According to the inventor's diligent studies, the reason that the friction coefficient is maintained at a low value is that the surface free energy of hydrogenated amorphous carbon (aC: H) is reduced by hydrogenation of silicon carbide (SiC: H). When compared with the above, the organic matter such as an ozone product and toner paper powder hardly adheres to and adheres to the surface of the photoreceptor, so that the formation of a filming layer is suppressed.
[0156]
Further, the initial surface roughness Rz was 0.27 μm, whereas the surface roughness Rz after the durability of 3 million sheets was 0.12 μm. The wear amount is 5 × 10 per 1000 rotations. ^-3 nm, which is also presumed to be due to the fact that adhesive wear is unlikely to occur.
[0157]
Further, in the third embodiment, even after the endurance of 3 million sheets, even in an environment of high temperature and high humidity (temperature of 32.5 ° C., humidity of 85%), image deletion occurs. Did not occur. No problem such as chipping occurred at the edge of the cleaning blade.
[0158]
Also, even after the endurance of 3 million sheets, the photosensitive drum 2 itself did not have any problems such as fusion, partial filming layer generation, rubbing, etc., which occur in the image. .
[0159]
Therefore, in the image forming apparatus according to the third embodiment, the same effects as in the first embodiment can be obtained.
[0160]
Next, a description will be given of a comparative example based on the related art for comparison with the image forming apparatuses according to the above-described first to third embodiments.
[0161]
(First Comparative Example)
In the image forming apparatus according to the first comparative example, unlike the first embodiment, a conventional OPC photoconductor having a surface layer of polycarbonate having a thickness of 20 μm is used as the photoconductor. Other basic configurations are the same as in the first embodiment.
[0162]
In addition, the linear pressure for cleaning required 55 g / cm (53.9 N / m) in the initial stage, and the initial surface roughness Rz was 1.0. Further, the surface roughness Rz reached 3.0 μm after about 10,000 sheets of durability, and cleaning failure occurred from this stage.
[0163]
(Second comparative example)
In the image forming apparatus according to the second comparative example, unlike the first embodiment, the rotation direction of the developing sleeve is sequentially changed at a speed of 400 mm / s (0.4 m / s) with respect to the photoconductor rotation direction. Direction. Other basic configurations are the same as in the first embodiment.
[0164]
In the second comparative example, when the inventor performed a durability test, it was confirmed that an image deletion occurred after about 30,000 sheets had been printed. In addition, since cleaning failure occurred after the execution of about 50,000 sheets, when the edge of the cleaning blade was observed, chipping of about 30 to 50 μm was observed in several places.
[0165]
(Third comparative example)
In the image forming apparatus according to the third comparative example, unlike the first embodiment, a toner manufactured by a conventionally known pulverizing method is used. In this toner, the average particle size and the external additive prescription are the same as those of the toner according to the first embodiment. Other basic configurations are the same as in the first embodiment.
[0166]
In the third comparative example, the present inventor first examined the slip-through of the cleaning blade and the allowable range of chatter at an early stage. As a result, it was confirmed that the allowable range was clearly reduced as compared with the allowable range of the polymerized toner having a spherical shape compared to the amorphous silicon photoreceptor according to the first embodiment.
[0167]
After about 50,000 durability tests were performed, it was confirmed that chatter of the cleaning blade occurred. Then, when the durability test was further continued, the cleaning blade was turned up after a predetermined time had elapsed.
[0168]
(Fourth comparative example)
In the image forming apparatus according to the fourth comparative example, unlike the first embodiment, the intermediate transfer member is formed by using a Young's modulus of 1.0 × 10 ³ A vinylidene fluoride and a polyvinylidene fluoride (PVDF) resin having a tensile strength of 80 N / cm at MPa are used. Other basic configurations are the same as in the first embodiment.
[0169]
In the fourth comparative example, when the inventor performed a durability test, the result was 10%. ⁵ It was confirmed that a peripheral flaw occurred on the surface of the intermediate transfer belt on about the number of sheets, and further, cleaning failure and filming fusion occurred from the peripheral flaw. As a result of the occurrence of the defect, it was confirmed that filming fusion was transferred also on the surface of the photoconductor.
[0170]
As described above, in the image forming apparatuses according to the first to third embodiments of the present invention, the surface of the photoreceptor is maintained in a state where the occurrence of image deletion is prevented and the occurrence of fusion is suppressed. The reliability of the electrophotographic apparatus can be greatly improved by cleaning the surface state by a cleaning member or the like. Further, in an image forming apparatus such as an electrophotographic apparatus, it is possible to obtain a full-color image forming apparatus of a one-drum rotary developing device capable of coping with a case where productivity significantly increases.
[0171]
Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments, and various modifications based on the technical idea of the present invention are possible.
[0172]
For example, the numerical values, materials, and mixing ratios described in the above embodiments are merely examples, and different numerical values, materials, and mixing ratios may be used as needed.
[0173]
In the above-described embodiment, a full-color copying machine is cited as a configuration example of the image forming apparatus. However, the present invention is not limited to this, and any printer having a photosensitive drum such as a facsimile and a monochrome copying machine may be used. It is possible to apply to the device.
[0174]
【The invention's effect】
As described above, according to the present invention, an image carrier, a charging unit for charging an outer surface of a photoconductor, and an exposure unit for irradiating light to the photoconductor are provided. Developing means having at least two types of developing devices for forming a toner image on the photoreceptor surface in accordance with the electrostatic latent image formed on the surface of the body, and a first means for contact-transferring the toner image to an intermediate transfer member Transfer means, a second transfer means for transferring the toner image on the intermediate transfer body to a transfer material, and a cleaning means for removing residual toner remaining on the surface of the photoreceptor, wherein the cleaning means comprises at least a cleaning blade and The magnetic brush has 10% by weight or more of abrasive particles constrained on the magnetic brush, and the surface of the image carrier is repeatedly cleaned by a cleaning unit. The surface roughness of the photoreceptor can be suppressed while the occurrence of image fusion can be suppressed, and the surface of the photoreceptor can be maintained in a state where the occurrence of image fusion can be suppressed. Therefore, the reliability of the image forming apparatus represented by the electrophotographic apparatus can be greatly improved, and even if the productivity of the image forming apparatus is dramatically improved in the future, the productivity of the image forming apparatus can be improved. Can be supported.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an image forming apparatus according to a first embodiment of the present invention.
[Explanation of symbols]
1 Primary charger
2 Photoconductor drum
3 Developing device
10 Platen glass
11 Exposure optical system
13 Exposure scanning device
31 Rotary axis
33a, 33b, 33c Developing device
35a, 35b, 35c Development roll
36a, 36b, 36c regulating blade
37 Developing sleeve
40 Intermediate transfer belt
41 Belt position sensor
42 Primary transfer roll
43 Tension roll
44 Backup Roll for Secondary Transfer
45 belt drive roll
46 Idler Roll
47 belt cleaner
48 Secondary transfer roll
50 one-component magnetic developing device
51 Developing sleeve
60 paper tray
61 Pickup Roll
62 cash register roll
63 sheet transport belt
64 fuser
64a heating roll
64b pressure roll
65 Recording sheet discharge tray
70 Cleaning device
71 Cleaning container
72 Cleaning blade
73 magnet roller

Claims (9)

A first image carrier, charging means for charging an outer surface of the first image carrier, and exposing means for irradiating the first image carrier with light; Developing means for forming a toner image on the surface of the first image carrier according to the electrostatic latent image formed on the surface of the first image carrier by means;
Transfer means for transferring the toner image to a second image carrier;
Cleaning means for removing residual toner remaining on the surface of the first image carrier;
The cleaning means comprises at least a cleaning blade and a magnetic brush,
10% by weight or more of abrasive particles are constrained by the magnetic brush, and the surface of the first image carrier is repeatedly cleaned by the cleaning means so that the first image carrier is cleaned. An image forming apparatus, wherein an average roughness of a surface is reduced. The second image carrier is an intermediate transfer member, and the intermediate transfer member is formed of a resin belt;
2. The resin belt according to claim 1, wherein the resin belt has a Young's modulus of 2.5 × 10 ³ MPa or more and a tensile strength of 1.0 × 10 ⁵ N / m (1000 N / cm) or more. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein said first image carrier is made of an amorphous silicon-based photoconductor. The image forming apparatus according to claim 3, wherein at least a surface of the first image carrier is made of hydrogenated amorphous carbon. The toner has a substantially spherical shape, and a developing sleeve of the developing device is configured to be rotatable in a counter direction with respect to the first image carrier and to be able to rub the surface of the first image carrier. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a two-component magnetic brush developing system. 6. The image forming apparatus according to claim 5, wherein the toner is a magnetic toner, and the toner has an average particle diameter of 6 μm or more and 10 μm or less. 6. The image according to claim 5, wherein the toner has at least a toner produced by a polymerization method having a shape factor SF-1 of 100 or more and 140 or less and a shape factor SF-2 of 100 or more and 120 or less. Forming equipment. At least abrasive particles having a Mohs' hardness of at least 6 are externally added to the toner matrix in a range of 0.01% by weight to 5.0% by weight, and the average particle diameter of the abrasive particles is 0.1% by weight. 2. The image forming apparatus according to claim 1, wherein the thickness is 5 μm or more and 3.0 μm or less. 2. The image forming apparatus according to claim 1, wherein the first image carrier is an electrophotographic photosensitive member.

Images