JP2004078113A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out stable cleaning even when a photoreceptor which has high durability and high strength and also has abrasion resistance improved and a small-sized toner of high sphericity are used in combination, to prolong the life of a cleaning assisting member, and to realize high picture quality and low running cost. <P>SOLUTION: A cleaning device which is provided to an image forming device having a photoreceptor (2), an electrostatic charging means, an exposing means, a developing means, and a collection container (8c) and cleans the photoreceptor is constituted so as to have a cleaning member (8a), a cleaning assisting member (8d), and a storage part (8j) in which part of a waste toner is collected. Part of the waste toner removed by the cleaning member or cleaning assisting member abutting against the photoreceptor is supplied to the storage part. The rest of the waste toner is supplied to the collection container. The toner in the storage part is applied to the photoreceptor through the cleaning assisting member. <P>COPYRIGHT: (C)2004,JPO

Description

（１）式において、ＡＲＥＡは、トナー投影面積であり、ＭＸＬＮＧは、トナーの絶対最大長（トナー粒子の直径）であり、ＰＥＲＩはトナー粒子の周長である。
【０１１８】
これらのトナーの形状係数のうち、ＳＦ−１は球形度合を示す。すなわち、形状係数ＳＦ−１が１００の場合、トナーは真球である。また、形状係数ＳＦ−１が１００〜１４０の範囲内の場合、トナーはほぼ球形である。また、形状係数ＳＦ−１が１４０よりも大きい場合には、数値の増加に伴い、トナーは、ほぼ球形から徐々に不定形になる。
【０１１９】
他方、形状係数ＳＦ−２は、トナー粒子表面の凹凸度合を示す。すなわち、形状係数ＳＦ−２が１００〜１２０の場合、トナーの表面は円滑である。また、形状係数ＳＦ−２が１２０よりも大きい場合、トナーの表面は凹凸が顕著になる。
【０１２０】
この第１の実施形態による画像形成装置に用いられる重合トナーとしては、高転写効率を維持するために、平均粒径が６μｍ以上１０μｍ以下、形状係数ＳＦ−１が１００〜１４０、形状係数ＳＦ−２が１００〜１２０のほぼ球形トナーが望ましい。
【０１２１】
また、この第１の実施形態において用いるトナーは、重合法によって製造される。そして、このトナーには、環境変動に対する被帯電性能安定化や流動性の向上のために、シリカや酸化チタンなどが外添されている。
【０１２２】
また、この第１の実施形態による画像形成装置において用いられる重合トナーは、従来の不定形な粉砕トナーに比して、球形度合が高く、大きさにばらつきがないことから、自己潤滑性が高い。そのため、トナーがクリーニングブレード８ａの当接部からすり抜けやすい状態となり、クリーニング不良が発生しやすくなっている。
【０１２３】
また、重合トナーは自己潤滑性が高いため、トナー間のせん断強さが小さくなり、粉砕トナーに比べて、感光ドラム２の表面の形状が、クリーニングブレード８ａのクリーニング性に大きな影響を与える。
【０１２４】
［クリーニング装置］
そこで、本発明者は、この第１の実施形態によるクリーニング装置を案出するに至った。次に、このクリーニング装置について説明する。図２に、この第１の実施形態によるクリーニング装置を示す。
【０１２５】
図２に示すように、この第１の実施形態によるクリーニング装置８は、クリーニング部材としてのクリーニングブレード８ａ、トナー捕集シート８ｂ、廃トナー回収容器８ｃ、クリーニング補助部材としてのクリーニング補助ブラシ８ｄ、スクレーパ部材としてのブラシスクレーパ８ｅ、板金８ｆ、隔壁８ｋおよびトナー貯留部８ｊを有して構成されている。また、クリーニングブレード８ａは、板金８ｆに支持されている。また、隔壁８ｋは、ブラシスクレーパ８ｅのほぼ直下に設置されている。
【０１２６】
次に、像担持体上の残存したトナーの挙動について説明する。
【０１２７】
まず、一次転写が終了した像担持体２の表面に残留するトナーは、クリーニング装置８を構成するクリーニングブレード８ａおよびクリーニング補助ブラシ８ｄにより像担持体２から除去される。
【０１２８】
次に、クリーニングブレード８ａから除去されたトナーはそのまま落下して、クリーニング補助ブラシ８ｄに降りかかる。このクリーニング補助ブラシ８ｄに降りかかったトナーは、このクリーニング補助ブラシ８ｄの回転に伴って移動し、ブラシスクレーパ８ｅによってクリーニング補助ブラシ８ｄから剥ぎ取られる。
【０１２９】
この剥ぎ取られたトナーは、落下して、隔壁８ｋにより、図２中実線矢印に示すように、一部がトナー貯留部８ｊに格納され、破線矢印に示すように、残部が廃トナー回収容器８ｃに格納される。
【０１３０】
また、クリーニング補助ブラシ８ｄによって像担持体２から掻き取られたトナーも自身の回転に伴って、ブラシスクレーパ８ｅにより掻き取られる。この掻き取られたトナーの一部は、トナー貯留部８ｊに格納され、残部は、廃トナー回収容器８ｃに格納される。
【０１３１】
また、クリーニング補助ブラシ８ｄの表面に付着したトナーは、クリーニング補助ブラシ８ｄのブラシスクレーパ８ｅにより、一度掻き落とされ、再び、トナー貯留部８ｊに溜まっているトナーをすくい上げて、その表面に担持される。
【０１３２】
その後、ブラシスクレーパ８ｅは、再び、像担持体２の表面を摺擦して、像担持体２上の転写残トナーをそのブラシで拡散して掻き取る。これと同時に、トナー貯留部８ｊからすくい上げたトナーを像担持体２に再塗布して、クリーニングブレード８ａにトナーを供給する。
【０１３３】
このように、像担持体表面で掻き取ったトナーを、一度、ブラシスクレーパ８ｅによりクリーニング補助ブラシ８ｄから剥ぎ取り、再びブラシのすくい上げによって、ブラシ繊維にトナーを保持して、像担持体２に供給していることにより、ブラシの連れ回りによる像担持体と連続的な摺擦がなくなり、像担持体、トナーおよびブラシに対するダメージを防止することができる。
【０１３４】
また、画像比率が大きく転写残トナーが多い場合や、紙詰まりなどによって、転写されることなく現像されたトナーがクリーナに到達した場合、ブラシによる掻き取り作用が働く。
【０１３５】
すなわち、像担持体としての像担持体２表面のトナーを多く掻き取り、クリーニング補助ブラシ８ｄの表面に付着した余分なトナーは、ブラシスクレーパ８ｅによって掻き落とされる。そして、トナーの一部がトナー貯留部８ｊに格納され、残部の多くのトナーが回収容器８ｃに回収される。
【０１３６】
このように、像担持体２上にトナーの多くが残存し、この状態が継続すると、トナー貯留部８ｊに供給されるトナーが多くなる。そこで、隔壁８ｋの高さを０．５〜５．０ｍｍ、好適には、１．０〜３．０ｍｍ、より好適には、１．５〜２．０ｍｍとする。そして、トナー貯留部８ｊに貯留されるトナーの上面が隔壁８ｋの上端を超えると、自動的に溢れ、廃トナー回収容器８ｃに回収される。
【０１３７】
なお、この隔壁８ｋの高さは、トナー捕集シート８ｂを固定しているクリーニング装置８の下あごの高さやトナーのブラシによる消費量などによって、適宜最適化されるべき数値である。
【０１３８】
また、画像比率が少ない場合においては、クリーニング補助ブラシ８ｄによりトナー貯留部８ｊの中の廃トナーがすくい上げられ、ブラシ繊維によって保持されて像担持体に接触されて、像担持体に廃トナーが供給される。
【０１３９】
これにより、クリーニングブレード８ａと像担持体２との接触部分に廃トナーが供給されることによって、像担持体とクリーニングブレード８ａとの滑り性が維持され、ブレード鳴きや捲れなどが防止される。
【０１４０】
また、クリーニング補助ブラシ８ｄによる像担持体２への廃トナー塗布量は、ベタ白画像から、未転写ベタ黒画像までのドラム上におけるトナー量が変化される。そして、本発明者が検討を行ったところ、廃トナー塗布量は、０．０５〜０．３ｋｇ／ｍ^２（０．０５〜０．３ｍｇ／ｍｍ^２）が適当であり、好適には、０．１〜０．２ｋｇ／ｍ^２（０．１〜０．２ｍｇ／ｍｍ^２）が良好であることを知見するに至った。
【０１４１】
また、像担持体２に対する塗布量を、初期の段階から安定化させるためには、あらかじめクリーニング補助ブラシ８ｄにトナーを塗布した状態にしたり、トナー貯留部８ｊにあらかじめトナーを補充したりすることが望ましい。
【０１４２】
この際、塗布されたり補充されたりするトナーとしては、現像に補給される補給剤でも廃トナーでもよく、さらには、初期塗布や補充の仕方としては、組み立て時に行ってもよいし、本体設置時に、いわゆる黒帯び形成などの方法によって、未転写トナーを供給することも可能である。
【０１４３】
ここで、クリーニング補助ブラシ８ｄは、基布に導電性の繊維を植え付けられ、それをφ６の芯金８ｈ上に巻き付けられてφ１６のブラシ状に構成されたものである。なお、芯金８ｈは、接地されている。ここで、この第１の実施形態においては、導電性繊維として、太さ７．０×１０^−５ｋｇ／ｍ（０．７Ｔｅｘ）のナイロンの導電糸を用い、繊維密度が９３ｍｍ^−２（１ｍｍ^２当たり９３本）となるようにＷ織りで基布に植え込んだものを、シート状に形成し、芯金８ｈとの導通を確保するように螺旋状に巻き付けられている。
【０１４４】
また、ブラシの条件としては、素材としてはナイロン、レーヨン、ポリエステル、またはアクリルなどの種々の素材を適用することが可能である。また、このブラシの織度としては、典型的には、０．３×１０^−６ｋｇ／ｍ以上２．２×１０^−６ｋｇ／ｍ以下であり、さらに、この範囲内においても、０．４×１０^−６ｋｇ／ｍ以上１．１×１０^−６ｋｇ／ｍ以下が好ましい。
【０１４５】
また、ブラシの繊維密度としては、典型的には、１５．５ｍｍ^−２以上３１０ｍｍ^−２以下（１ｍｍ^２当たり１５．５本以上３１０本以下）、好ましくは、４６．５ｍｍ^−２以上１５５ｍｍ^−２以下（１ｍｍ^２当たり４６．５本以上１５５本以下）とする。
【０１４６】
また、図２に示すように、このクリーニング補助ブラシ８ｄは、像担持体２の回転方向に沿った、クリーニングブレード８ａの上流側に配設され、像担持体２に対する侵入量αが１ｍｍになるように当接され、回転可能に配設されている。
【０１４７】
また、図３に示すように、像担持体２と逆方向回転である矢印Ｂ方向に６０ｒｐｍの速度で回転駆動されている。すなわち、像担持体２とクリーニング補助ブラシ８ｄとは、接触部位において相互に同方向に回動している。
【０１４８】
この接触部位においては、一次転写後の像担持体２上の転写残トナーが掻き取られる。または、転写残トナーの像担持体２との付着力が弱められることにより、後述のクリーニングブレード８ａにおけるクリーニングを容易にする。
【０１４９】
さらに、この接触部位においては、画像比率が少なく、転写残トナーがほとんど存在しない場合であっても、上述したように、クリーニング補助ブラシ８ｄの作用により、廃トナーがクリーニングブレード８ａに適切な量だけ給送される。そのため、ブレード鳴きや捲れなどを抑止することが可能となる。
【０１５０】
また、クリーニング補助ブラシ８ｄは、クリーニング動作を繰り返し行うとブラシ繊維が目詰まりを起こしてトナーロール化し、クリーニング性能が低下してしまう。これを防止するために、ブラシ繊維に溜まったトナーを掻き落とす部材であるブラシスクレーパ８ｅが設けられている。
【０１５１】
また、図３に示すように、この第１の実施形態においては、ブラシスクレーパ８ｅとして可撓性を有する、たとえば０．１ｍｍの厚さのポリエチレンテレフタレート（ＰＥＴ）からなるシートを板金に貼り付け、その自由長を２ｍｍとし、クリーニング補助ブラシ８ｄに対する侵入量βを１．０ｍｍとしている。
【０１５２】
ここで、本発明者が侵入量αと侵入量βとの関係に着目して、鋭意検討を行ったところ、α≧βを満足する関係が必要であることを知見するに至った。
【０１５３】
すなわち、像担持体２に対するブラシの侵入量αよりも、ブラシスクレーパ８ｅに対するブラシの侵入量βが大きくなると、スクレーパでのブラシに対する掻き落としの作用が強くなりすぎる。これにより、像担持体２に対するトナーの塗布量を十分に確保することが困難になる。
【０１５４】
また、スクレーパシートの材質、厚み、自由長にもよるが、侵入量βを大きく設定しすぎると、耐久により捲れが発生することとなる。さらに、スクレープ作用が強すぎると、像担持体への塗布量が十分に確保できなくなる可能性もある。
【０１５５】
そこで、本発明者がこの第１の実施形態に基づいて検討を行ったところ、構成において侵入量βを２．５ｍｍ以上に設定すると、捲れが生じることを知見するに至った。
【０１５６】
さらに、ブラシスクレーパ８ｅのスクレーパシートを、高硬度の材質から構成すると、たとえば１〜２ｍｍの厚さの板金を用いた場合に、逆にブラシの方の毛倒れが起こり、ブラシの外径が小さくなりやすく、本来のブラシの機能が果たせなくなるという問題が発生する。
【０１５７】
したがって、以上のことを勘案して、ブラシスクレーパ８ｅの選定や設定を行う必要がある。
【０１５８】
また、ブラシスクレーパ８ｅのスクレーパシートとしては、ある程度撓む性質を有するものであればよく、耐久性を重視して、高摺動性を有する高密度ポリエチレンシートなどを用いることが可能である。
【０１５９】
また、スクレーパシートとしては、材質それ自体に離型性のあるものをシート状に形成したものや、表面に離型製の高いシリコーンコートが施されたシートなどを用いることも可能である。これにより、特に、クリーニング補助ブラシ８ｄを高速回転で使用した際に発生することがある、シートへのトナー固着を防止することが可能である。
【０１６０】
一方、クリーニングブレード８ａは、板金８ｆの先端部に一体的に保持されたポリウレタンゴムからなる。そして、図４に示すように、クリーニングブレード８ａは、像担持体２に対して所定の侵入量δ、設定角θの条件で当接されている。
【０１６１】
この第１の実施形態において、本発明者が鋭意検討を行った結果、クリーニングブレード８ａのゴム硬度として、典型的に５０〜８５度（ＪＩＳＡ）、好適には、６０〜８０度（ＪＩＳＡ）の範囲内が好ましいことが確認された。そこで、この第１の実施形態においては、ゴム硬度が７０度（ＪＩＳＡ）のクリーニングブレード８ａを用い、θ＝２２°およびδ＝１．０に設定して、像担持体２に対する当接圧を約３９Ｎ／ｍ（４０ｇ／ｃｍ）としている。
【０１６２】
ここで、この第１の実施形態による効果を確認するために、低温低湿（温度２３℃で湿度５％）、常温常湿（温度２３℃で湿度６０％）および高温高湿（温度３０℃で湿度８０％）のそれぞれの環境下において、連続プリントによる２００００枚の耐久試験を行い、クリーニング性およびその他の不具合などを調べる実験を行った。なお、この耐久試験は、１日当たり２５００枚の印刷を８日間連続して実施した。
【０１６３】
この耐久試験の結果、この第１の実施形態の構成においては、耐久を通してクリーニング不良やブレードの鳴きや捲れなどの不具合は一度も発生せず、像担持体２の寿命を通して良質な画像形成を実行可能であることが確認された。
【０１６４】
また、耐久試験後に、クリーニング補助ブラシ８ｄによる像担持体２への塗布量を測定したところ、初期に設定した値をほぼ維持していた。さらに、転写残トナーのクリーニング時のクリーニング補助ブラシ通過前後におけるクリーニング性能を確認したところ、初期の状態をほぼ維持していた。これらにより、転写残トナーの確実な除去を行うことができることが確認された。
【０１６５】
（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おけるクリーニング装置について説明する。
【０１６６】
この第２の実施形態によるクリーニング装置においては、第１の実施形態において用いられたブラシの代わりに、スポンジローラを用いる。この第２の実施形態によるクリーニング装置におけるその他の構成は、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、図面についても図２を援用する。
【０１６７】
この第２の実施形態によるスポンジローラは、発泡ポリウレタン、発泡シリコーン、発泡ＥＰＤＭなどを材質としたスポンジからなる。具体的には、たとえば発泡ポリウレタンは、ポリイソシアネートプレポリマーおよびポリエーテル系ポリオールを主体とした主原料と、アルキルベンゼン溶媒にシリコーンを溶かした整泡剤の低粘性混合液とを配合して調整溶液を作り、これを反応成形してウレタンゴムスポンジ体のローラ本体を成形し、このローラにシャフトを装着することにより製造される。
【０１６８】
また、スポンジローラの外径は、たとえば１５．４ｍｍである。また、スポンジローラの硬度は、３０度（アスカーＣ）である。なお、硬度としては、典型的には、１０〜５０°（アスカーＣ）であり、好適には、２０°〜４０°である。これは、スポンジローラの硬度が１０度未満であると、摺擦力が不足してしまうからであり、他方、硬度が５０度を超えると、像担持体を傷つけてしまう可能性が高くなるからである。
【０１６９】
また、スポンジローラの表面のセルの大きさは、像担持体２の表面の転写残トナーの掻き取りや、廃トナー塗布に影響する。そのため、セルの直径は、０．１〜１００μｍが好適であり、さらに１〜１０μｍがより好適である。これは、セルの直径が０．１μｍ未満となると、掻き取りや塗布能力が不足してしまい、他方、セルの直径が１００μｍを超えると、トナーの目詰まりが発生しやすくなるためである。
【０１７０】
また、スポンジローラは、像担持体に対して、０．７ｍｍの侵入量α、かつ５８．８Ｎ／ｍ（６０ｇｆ／ｃｍ）の線圧で当接している。
【０１７１】
また、このスポンジローラは、像担持体２の回転方向に沿ってクリーニングブレード８ａの上流側に、回転可能に配設されており、像担持体２と逆方向回転である矢印Ｂ方向に６０ｒｐｍの速度で回転駆動されている。すなわち、像担持体２とクリーニング補助ブラシ８ｄとは、接触部位において相互に同方向に回動している。
【０１７２】
また、ブラシスクレーパ８ｅとしては、スポンジローラに対して侵入量βは０．３ｍｍに設定されている。
【０１７３】
以上のような構成で、この第２の実施形態によるクリーニング装置の効果を確認するために、低温低湿（温度２３℃で湿度５％）、常温常湿（温度２３℃で湿度６０％）、および高温高湿（温度３０℃で湿度８０％）のそれぞれの環境下において、耐久試験を行った。すなわち、連続プリントによる１００００枚の耐久試験を行い、クリーニング性およびその他の不具合などを調べる実験を行った。この耐久試験は、１日当たり２５００枚のプリントを行い、４日間連続で実施した。
【０１７４】
この耐久試験の結果、この第２の実施形態によるクリーニング装置の構成においては、耐久試験を通じて、クリーニング不良やブレードの鳴きや捲れなどの不具合が一度も発生することなく、像担持体２の寿命を通じて良質な画像形成を行うことが可能であることが確認された。
【０１７５】
（第３の実施形態）
次に、この発明の第３の実施形態によるクリーニング装置について説明する。図５に、この第３の実施形態によるクリーニング装置を示す。
【０１７６】
図５に示すように、この第３の実施形態による画像形成装置のクリーニング装置８においては、クリーニング補助ブラシ８ｄに潤滑剤８ｍを当接し、クリーニング補助ブラシ８ｄを介して像担持体２の表面に塗布するように構成されている。
【０１７７】
このように、像担持体２の表面を滑らかにすることにより、特にクリーニングブレード８ａにおけるビビリなどの動きを抑制することができる。
【０１７８】
また、この第３の実施形態において用いられる球形のトナーや高硬度の感光体ドラムであっても、クリーニング効果がよりいっそう向上させることができる。
【０１７９】
また、像担持体２の表面に潤滑剤８ｍの薄膜を均一に張ることにより、トナーや外添剤の静電的な付着力を低減させることができる。ここで、この潤滑剤８ｍとしては、ステアリン酸亜鉛などの金属石鹸を用い、硬度はＪＩＳ鉛筆硬度により規定されたものが用いられる。
【０１８０】
この金属石鹸としては、固形化前の粉体のものからなり、みかけ比重が０．５０〜０．７５ｇ／ｍｍｌである。そして、この金属石鹸に対して融解処理を施したり、冷却処理を施したりすることによって固体化し、ＪＩＳ鉛筆硬度のＢになるように調節されている。なお、金属石鹸としては、ステアリン酸亜鉛以外にも、ステアリン酸鉄、ステアリン酸錫、パルチミン酸マグネシウム、パルチミン酸カルシウム、オレイン酸マンガン、オレイン酸鉛などの比較的高次の脂肪酸を用いることが可能である。
【０１８１】
潤滑剤８ｍは、経時的な画像形成プロセスに伴い、クリーニング補助ブラシ８ｄによる像担持体２への塗布、供給動作により切削、磨耗されて形状が変化し、初期と比較して塗布量が次第に減少する。
【０１８２】
このとき、従来技術においては、潤滑剤８ｍの固定部材（図示せず）をバネなどの加圧手段によって背面より常にクリーニング補助ブラシ８ｄに押しつけ、潤滑剤８ｍを経時的に均一に塗布している。
【０１８３】
このステアリン酸亜鉛からなる潤滑剤の塗布による滑り性向上の効果を確認するため、１００００枚の通紙試験を行ったところ、水に対する接触角および滑り性を比較すると以下の結果が得られた。
【０１８４】
潤滑剤なしの場合に接触角が５０°で滑り性が１．１であり、潤滑剤ありの場合に接触角が６０°で滑り性が１．０であった。なお、ここでの滑り性は、ヘイドン社製の滑り性試験機により測定されるものであり、ポリエチレンテレフタレート（ＰＥＴ）の滑り性を１とした場合の被測定物の滑り性を対ＰＢＴ比で示したものである。そして、この滑り性の値は、小さいほど滑り性に優れていることを示している。
【０１８５】
さらに、この第３の実施形態による効果を確認するため、低温低湿（温度２３℃で湿度５％）、常温常湿（温度２３℃で湿度６０％）、高温高湿（温度３０℃で湿度８０％）のそれぞれの各環境下において、連続プリントによる１０００００枚の耐久試験を行い、クリーニング性およびその他の不具合などを調べる実験を行った。なお、この耐久試験は、１日あたり５０００枚印刷し、２０日間連続実施した。
【０１８６】
この耐久試験の結果、この第３の実施形態の構成においては、耐久試験を通じてクリーニング不良やブレードの鳴きや捲れなどの不具合が一度も発生することなく、像担持体２の寿命を通して良質な画像形成を行うことができた。
【０１８７】
また、耐久試験後にクリーニング補助ブラシ８ｄによる像担持体２への塗布量を測定したところ、初期に設定した値がほぼ維持されていた。さらに転写残トナーのクリーニング時のクリーニング補助ブラシ通過前後におけるクリーニング性能を確認したところ、初期の状態がほぼ維持されていた。これらのことから、転写残トナーの確実な除去を行うことができることが確認された。
【０１８８】
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。
【０１８９】
たとえば、上述の実施形態において挙げた分子量や粒径、数値はあくまでも例に過ぎず、必要に応じてこれと異なる分子量や粒径、数値を用いてもよい。
【０１９０】
なお、本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現像剤のクリーニング装置を備えたものに適用することが可能である。
【０１９１】
また、たとえば上述の第１の実施形態においては、転写性の良好であるという観点から、重合法による球形トナーを用いたが、必ずしも重合法により製造されたトナーに限定するものではなく、たとえば従来の機械的な粉砕分級法にて作成したものに熱的または機械的な後処理を施して丸くしたトナーを用いることも可能である。
【０１９２】
また、たとえば上述の第３の実施形態においては、クリーニング補助部材と像担持体との回転方向を互いに逆方向とし、接触部において同じ方向としたが、回転方向は逆にすることも可能である。
【０１９３】
また、たとえば上述の第３の実施形態においては、クリーニング補助部材およびクリーニング部材からスクレープされたトナーが、自然落下によりトナー溜まりに回収される構成としたが、一旦像担持体から剥ぎ取ったトナーを廃トナー回収容器に全て集めた後に、その中の一部を、再びクリーニング補助部材を介して像担持体２に塗布するような構成とすることも可能であり、この場合も同様の効果を得ることができる。
【０１９４】
【発明の効果】
以上説明したように、この発明によれば、クリーニングが困難な、高硬度の感光体と小粒径の現像剤（特に球形形状の現像剤）を使用する場合において、クリーニング手段を、少なくともクリーニング部材と、クリーニング部材に対して像担持体の回転方向上流側にあるクリーニング補助部材と、廃現像剤貯留部とを設けて構成し、これらのうちのクリーニング部材およびクリーニング補助部材の少なくとも一方の部材によって、像担持体の表面から掻き取られた廃現像剤の一部を、現像剤貯留部に給送し、残部の掻き取られた転写残現像剤をトナー回収容器に給送し、現像剤貯留部に送られた現像剤を、クリーニング補助部材を介して、クリーニング補助部材とクリーニング部材との間の像担持体に塗布するようにしていることにより、長期にわたるクリーニング不良やブレードの鳴き、捲れなどの発生を防止することができ、安定したクリーニングを実行することが可能となる。
【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の概略構成を示す断面図である。
【図２】この発明の第１の実施形態によるクリーニング装置の概略構成を示す断面図である。
【図３】この発明の第１の実施形態によるクリーニング補助ブラシを示す部分拡大図である。
【図４】この発明の第１の実施形態によるクリーニングブレードの、像担持体に対する侵入量δおよび設定角θを説明するための部分拡大図である。
【図５】この発明の第３の実施形態によるクリーニング装置の概略構成を示す断面図である。
【符号の説明】
１　画像形成装置
２　像担持体
３　帯電ローラ
４　レーザ発振器
５　レーザービーム
６　回転現像装置
６ｙ　第１の現像装置
６ｍ　第２の現像装置
６ｃ　第３の現像装置
６ｋ　第４の現像装置
７　中間転写体
７ａ，７ｂ　転写部位
７ｃ　高圧電源
８　クリーニング装置
８ａ　クリーニングブレード
８ｂ　トナー捕集シート
８ｃ　廃トナー回収容器
８ｄ　クリーニング補助ブラシ
８ｅ　ブラシスクレーパ
８ｆ　板金
８ｈ　芯金
８ｊ　トナー貯留部
８ｋ　隔壁
８ｍ　潤滑剤
９　カセット
１０　ピックアップローラ
１１　レジストローラ対
１２　転写ベルト
１２ａ　バイアスローラ
１２ｂ　テンションローラ
１２ｃ　高圧電源
１３　中間転写体クリーニング装置
１４　定着機
１５　排出ローラ対
Ｓ　記録媒体[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus, and in particular, is suitably applied to an image forming apparatus using an electrophotographic system and having a function of cleaning residual toner remaining on the surface of a photosensitive drum.
[0002]
[Prior art]
2. Description of the Related Art Generally, in an image forming apparatus that records an image on a recording medium such as paper, such as a copier, a printer, and a facsimile, an electrophotographic system is used as a system that records an image on a recording medium.
[0003]
In an electrophotographic system, a photosensitive drum having a surface coated with a photosensitive material is used as an image carrier. First, after the surface of the photosensitive drum is uniformly charged, the surface of the photosensitive drum is irradiated with laser light, and a potential difference is applied between the irradiated part and the non-irradiated part.
[0004]
Next, the charged toner contained in the developer adheres to the surface of the photosensitive drum, so that a toner image is formed on the surface of the photosensitive drum. Thereafter, the toner image is transferred to a recording medium, and an image is formed on the recording medium.
[0005]
Recently, there has been an increasing demand for higher image quality and lower running costs of output devices, and as a photosensitive drum as an image carrier used in the above-described electrophotographic system, the need for a higher resolution requires a higher photosensitive layer thickness. Thinner ones are used, and on top of that, the need to extend the life of the photosensitive drum itself in order to reduce running costs has led to improvements in the electrical, mechanical strength and abrasion resistance of the surface of the photosensitive member. I have.
[0006]
Further, in such an electrophotographic system, since the surface of the photosensitive drum is repeatedly used for forming a toner image, the photosensitive drum is not transferred to the recording medium after the toner image is transferred to the recording medium. It is necessary to sufficiently remove the residual toner remaining on the surface of the drum.
[0007]
Various methods have been conventionally proposed for removing the residual toner. Among these proposals, a method in which a counter blade (cleaning blade) made of an elastic material is brought into contact with the surface of a photosensitive drum to scrape off residual toner has been widely put to practical use. This method is inexpensive, can make the whole electrophotographic system simple and compact, and has excellent toner removal efficiency.
[0008]
As a material for the cleaning blade, urethane rubber which is high in hardness and rich in elasticity and excellent in abrasion resistance, mechanical strength, oil resistance, ozone resistance and the like is generally used.
[0009]
The physical properties of the cleaning blade and the method of contacting the image carrier with the cleaning blade greatly depend on the ease of cleaning due to the degree of adhesion of the transfer residual toner to the image carrier, the surface properties of the image carrier, and the like.
[0010]
Further, since the cleaning property is greatly affected by the physical properties such as the toner shape, particle diameter, and material, it is necessary to select an appropriate blade and set an appropriate angle and an appropriate contact load with respect to the image carrier. . Therefore, in the actual selection and setting of the cleaning blade, trial and error have been repeated to find the optimum conditions.
[0011]
On the other hand, the cleaning performance and the degree of wear of the surface layer of the image carrier differ depending on the actual operating environment, particularly, fluctuations in temperature and humidity. For this reason, it is difficult to clean only the cleaning blade throughout the durability life of the image carrier. Therefore, an apparatus provided with a cleaning auxiliary member has been proposed.
[0012]
For example, a configuration in which the magnetic developer is collected by a magnet roller and the magnetic developer is rubbed on the image carrier (Japanese Patent Laid-Open No. 2-91675), or a porous elastic roller is rubbed on the image carrier. A configuration (JP-A-60-107076) and the like have been proposed.
[0013]
In order to improve the image quality, it is essential to reduce the diameter of the toner. For this reason, the tendency of the diameter of the toner to be smaller has become remarkable. Then, as the particle diameter of the toner decreases, the specific surface area between the toner and the surface of the photosensitive drum increases. As a result, the adhesion of the toner to the surface of the photosensitive drum per unit weight increases, and the cleaning performance of the surface of the photosensitive drum deteriorates.
[0014]
Further, as the particle size of the toner becomes smaller, the fluidity of the toner becomes worse. Therefore, a larger amount of additives is required. Then, such a large amount of additives causes a problem that the cleaning blade is worn or chipped, and a local streak is generated on the surface of the photosensitive drum.
[0015]
In recent years, a polymerized toner produced by a polymerization method has been adopted instead of a pulverized toner produced by a conventional pulverization method. This polymerized toner has the advantage that the transfer efficiency is higher than that of the pulverized toner, and that a release agent is not required at the time of fixing the transferred image.
[0016]
Further, the polymerized toner has a feature that the sphericity is higher than the pulverized toner. When the surface state of the photosensitive drum and the contact pressure of the cleaning blade are the same as in the case of the pulverized toner, the use of the polymerized toner increases the slippage from the cleaning blade due to the improvement in the sphericity of the toner. Would.
[0017]
Generally, in an image forming apparatus using a polymerized toner, the toner is prevented from passing through by increasing the contact pressure of a cleaning blade. In this case, in order to reduce the load on the cleaning blade, a cleaning auxiliary member is additionally provided as described above, and the cleaning auxiliary member is configured to scrape toner in advance.
[0018]
[Problems to be solved by the invention]
However, the above-described conventional image forming apparatus has the following problems in recent years due to demands for higher image quality and lower running costs.
[0019]
That is, in recent years, a toner having a high sphericity has been used, as typified by a toner having a small particle diameter and a polymerized toner. Therefore, the adhesion to the photosensitive drum increases, and it is necessary to increase the contact pressure of the cleaning blade.
[0020]
On the other hand, so-called highly durable photosensitive drums having high strength and high abrasion resistance have been used. As a result, when a photosensitive drum having a very high abrasion resistance with a surface wear amount defined by a Taber abrasion tester of 2 mg or less, particularly in the photosensitive layer, is used, the surface of the photosensitive drum is scraped, and the refresh is performed. It will be difficult.
[0021]
As described above, when refreshing becomes difficult, electrical damage caused by charging and the like, surface degradation due to adhesion of discharge products, and mechanical damage due to rubbing with a cleaning blade or the like accumulate for a long period of time.
[0022]
Then, the slipperiness of the surface of the photosensitive drum, particularly, the slipperiness with respect to the cleaning blade is reduced. As a result, chattering, squealing and turning of the cleaning blade easily occur. For this reason, it has been difficult to increase the contact pressure of the cleaning blade, which has led to a contradictory situation.
[0023]
In addition, as shown in the above-described related art, the use of the cleaning auxiliary member is an effective means from the viewpoint of reducing the load on the cleaning blade. However, the adoption of the cleaning auxiliary member, on the other hand, has the following problems.
[0024]
That is, in the configuration in which the magnetic developer is collected by the magnet roller and the magnetic toner is rubbed on the image carrier, the rubbing is performed by the magnetic toner held by the magnetic force. It is.
[0025]
The color toner is a non-magnetic toner. Therefore, in the above-described configuration, the non-magnetic toner remaining as a transfer remaining on the surface of the photosensitive drum cannot be sufficiently removed, thereby making it difficult to collect the non-magnetic toner.
[0026]
Further, the configuration in which the porous elastic roller is rubbed against the image carrier has an advantage that the rubbing force is sufficiently exerted.
[0027]
However, it has been necessary to remove toner adhered to the roller itself by scraping off the surface of the photosensitive drum by other means. If the toner adhering to the roller itself is not scraped off, rubbing is repeated between the photosensitive drum and the roller in a state where the toner always adheres to the roller, and fusion occurs.
[0028]
Conversely, when the toner adhered to the surface of the roller can be sufficiently scraped off and the amount of untransferred toner can be reduced, the roller surface directly contacts the surface of the photosensitive drum and is rubbed, and The surface may be damaged.
[0029]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and overcome the drawbacks of the conventional cleaning assisting member, thereby providing an image carrier having high durability, high strength and improved wear resistance. By using a toner having a small diameter and a high sphericity, it is possible to stably perform cleaning even in a situation where the cleaning property is extremely severe. It is an object of the present invention to provide an image forming apparatus capable of achieving high image quality and low running cost.
[0030]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides
A part of the waste developer removed from the surface of the image carrier by the cleaning member in contact with the image carrier is supplied to the waste developer storage unit, and a part of the waste developer is cleaned by the cleaning member. And applying the remaining developer to the image carrier, and collecting the remaining waste developer in a developer collection container.
[0031]
That is, specifically, the present invention
An image carrier;
Charging means for charging the image carrier,
Exposure means for forming a latent image by performing image exposure on the image carrier charged by the charging means,
Developing means for developing the latent image as an image;
Cleaning means for cleaning the image carrier after the developed image is transferred,
Having a developer collection container for storing the transfer residual developer,
The surface polishing amount of the image carrier is 2 mg or less;
The cleaning unit has at least a cleaning member, a cleaning auxiliary member, and a waste developer storage unit that stores a part of the waste developer removed from the surface of the image carrier by the cleaning member or the cleaning auxiliary member. Composed,
A part of the waste developer removed from the surface of the image carrier by at least one of the cleaning member and the cleaning auxiliary member that is in contact with the image carrier is supplied to a waste developer reservoir, and a transfer residue of the remaining developer is transferred. Supplying the developer to the developer collection container,
The developer supplied to the waste developer reservoir is applied to the image carrier via the cleaning auxiliary member.
It is characterized by the following.
[0032]
In the present invention, typically, the cleaning auxiliary member is provided upstream of the cleaning member in the rotation direction of the image carrier.
[0033]
In the present invention, typically, the surface layer of the photosensitive layer in the image carrier contains at least a compound cured by polymerization or crosslinking of a hole transporting compound having a chain polymerizable functional group. Preferably, the surface layer of the photosensitive layer in the image bearing member is formed by applying a hole transporting compound having at least a chain polymerizable functional group to the surface layer of the photosensitive layer in the image bearing member by radiation (electron beam) irradiation. It is composed of an electrophotographic photoreceptor containing a compound cured by polymerization or crosslinking. More preferably, the surface polishing amount of the electrophotographic photoreceptor defined by the Taber abrasion test is 2 mg or less.
[0034]
In addition, in the present invention, typically, at least one of the cleaning auxiliary member and the toner reservoir is preliminarily attached or replenished with toner.
[0035]
In the present invention, typically, at least one of the cleaning member and the cleaning auxiliary member has a scraper member for scraping off and removing the attached toner.
[0036]
In the present invention, typically, a lubricant is applied to the auxiliary cleaning member by contact, and the lubricant is applied to the image carrier via the auxiliary cleaning member.
[0037]
In the present invention, preferably, a relationship of α ≧ β is established between the penetration amount α of the cleaning auxiliary member into the image carrier and the penetration amount β of the scraper member into the cleaning auxiliary member.
[0038]
In the present invention, typically, the cleaning member is formed of a rubber blade having elasticity and contacting the image carrier.
[0039]
In the present invention, typically, the weave of the cleaning auxiliary member is 0.2 × 10 ^-6 3.3 × 10 over kg / m ^-6 It is composed of a fur brush having brush fibers of kg / m or less.
[0040]
In the present invention, typically, the cleaning auxiliary member is a sponge roller having a surface cell structure of 0.1 μm to 100 μm.
[0041]
In the present invention, typically, the toner has a shape factor SF-1 of 100 or more and 150 or less, and a shape factor SF-2 of 100 or more and 140 or less.
[0042]
In the present invention, the amount of wear is an amount measured based on a Taber abrasion test. In the present invention, typically, a photosensitive layer is provided on the surface of the image carrier, and the surface wear of the photosensitive layer in the image carrier is 6 mg or less.
[0043]
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.
[0044]
(1st Embodiment)
First, an image forming apparatus and a cleaning device according to a first embodiment of the present invention will be described. FIG. 1 shows an image forming apparatus according to the first embodiment, and FIG. 2 shows a cleaning apparatus according to the first embodiment.
[0045]
[overall structure]
As shown in FIG. 1, an image forming apparatus 1 according to the first embodiment is an electrophotographic color copying machine. The image forming apparatus 1 is configured to form an image on a recording medium S such as recording paper based on an image signal supplied from a computer (not shown).
[0046]
In the image forming apparatus 1 according to the first embodiment, an image carrier 2 is formed by applying a photosensitive material such as OPC to an outer peripheral surface of a cylindrical base such as aluminum.
[0047]
In the image carrier 2, first, while being rotated at a peripheral speed of 200 mm / s, the dark portion potential V _D , A potential of about -600 V is uniformly charged.
[0048]
Next, a laser beam 5 whose ON / OFF is controlled in accordance with image information is scanned and exposed by the laser oscillator 4 on the image carrier 2. As a result, the bright portion potential V _L , An electrostatic latent image of about -200 V is formed.
[0049]
The electrostatic latent image thus formed is developed by the rotary developing device 6 with toner as a developer, and is visualized.
[0050]
Here, the rotary developing device 6 includes a first developing device 6y containing yellow toner as the first color toner and a second developing device 6m containing magenta toner as the second color toner. And a third developing device 6c containing a cyan toner as a third color toner and a fourth developing device 6k containing a black toner as a fourth color toner. ing.
[0051]
Then, of the electrostatic latent images formed by these developing devices, the first electrostatic latent image is developed by the first developing device 6y to be visualized. In addition, as a developing method, a jumping developing method, a two-component developing method, an FEED developing method, or the like is used. As a developing method, image exposure and reversal development are often used in combination. Here, in the first embodiment, a two-component developing method using a non-magnetic toner is used.
[0052]
The visualized first color toner image is electrostatically charged on the surface of the intermediate transfer member 7 at a first transfer portion 7a facing the intermediate transfer member 7 as a second image carrier that is driven to rotate. It is transferred and primary transferred.
[0053]
The intermediate transfer member 7 is formed of a conductive elastic layer and a surface layer having releasability. The intermediate transfer member 7 has a circumference slightly longer than the length of the maximum transportable recording medium.
[0054]
Further, the intermediate transfer member 7 is pressed against the image carrier 2 with a predetermined pressing force, and moves in the opposite direction to the rotation direction of the image carrier 2, that is, in the same direction at the contact portion. It is rotationally driven at a peripheral speed substantially equal to the peripheral speed.
[0055]
Further, a voltage having a polarity opposite to the charge polarity of the toner, that is, a so-called primary transfer bias is applied to the cylinder portion of the intermediate transfer body 7 by the high voltage power supply 7c, so that the toner image is primarily transferred onto the surface of the intermediate transfer body 7. Is done.
[0056]
Thereafter, the toner remaining on the surface of the image carrier 2 after the primary transfer is removed by the cleaning device 8.
[0057]
Subsequently, the process is sequentially repeated for each color, and the four color toner images are transferred onto the intermediate transfer member 7 and superimposed.
[0058]
Further, a recording medium S such as recording paper is loaded on the cassette 9. Then, the recording medium S is separated and fed one by one from the cassette 9 by the pickup roller 10.
[0059]
The separated and fed recording medium S is corrected for skew by the registration roller pair 11, and then reaches the transfer portion 7b. Here, the transfer belt 12 separated from the surface of the intermediate transfer member 7 is pressed against the surface of the intermediate transfer member 7 with a predetermined pressing force and is rotationally driven. The transfer belt 12 is stretched by a bias roller 12a and a tension roller 12b. Further, a voltage (secondary transfer bias) having a polarity opposite to the polarity of the charged toner is applied to the bias roller 12a by the high voltage power supply 12c.
[0060]
Thus, the toner image on the intermediate transfer body 7 is collectively transferred to the surface of the recording medium S conveyed at a predetermined timing toward the second transfer portion 7b, and the secondary transfer is performed.
[0061]
Thereafter, the recording medium S is fed to a fixing device 14 as a fixing unit, and the image is fixed by heating and pressing. Subsequently, the recording medium S is discharged outside the apparatus by the discharge roller pair 15.
[0062]
On the other hand, the toner remaining on the surface of the intermediate transfer member 7 after the completion of the secondary transfer is removed by the intermediate transfer member cleaning device 13 which comes into contact with the surface of the intermediate transfer member 7 at a predetermined timing.
[0063]
[Image carrier]
Next, a photosensitive drum as an image carrier according to the first embodiment of the present invention will be described below.
[0064]
The photosensitive drum used in the first embodiment is made of an electrophotographic photosensitive member containing a compound in which at least the surface layer is polymerized or crosslinked and cured. As the curing means, heat, light such as visible light or ultraviolet light, and further radiation can be used.
[0065]
Therefore, in the first embodiment, as a method of forming the surface layer of the photoreceptor, using a coating solution that melts or contains a compound curable by polymerization or crosslinking, which is used for the surface layer, After applying by dip coating, spray coating, curtain coating, spin coating, or the like, a method of curing the applied compound by a curing means is employed.
[0066]
Among these, the most preferable method for mass-producing the photosensitive member is the dip coating method. In the first embodiment, the dip coating method can be employed.
[0067]
The photosensitive drum according to the first embodiment has a single-layer structure in which both a charge generating substance and a charge transporting substance are contained in the same layer on a conductive substrate having an outer diameter of, for example, about 62 mm. Or a stacked type in which a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance are laminated sequentially or in reverse order. Further, it is possible to form a surface protective layer on the photosensitive layer.
[0068]
In the first embodiment of the present invention, if at least the surface layer of the photoreceptor contains a compound that can be polymerized or cross-linked and cured by heat, visible light, light such as ultraviolet light, and further radiation. Good. Preferably, from the viewpoint of the characteristics as a photoconductor, in particular, electrical characteristics such as residual potential and durability, a function-separated type photoconductor in which a charge generation layer and a charge transport layer are sequentially laminated, It is preferable that a surface protective layer is further formed on the photosensitive layer laminated with the photosensitive member configuration of the mold.
[0069]
In the first embodiment, the method for curing the compound in the polymerization or crosslinking in the surface layer is such that the photoconductor characteristics are less deteriorated, the residual potential does not increase, and sufficient hardness is exhibited. Preferably, radiation is used because it is possible.
[0070]
The radiation used to generate the polymerization or crosslinking is preferably an electron beam or a gamma ray. When an electron beam is used, any type of accelerator, such as a scanning type, an electron curtain type, a broad beam type, a pulse type, and a lamina type, can be used.
[0071]
In the case of irradiating an electron beam, in order to develop the electrical characteristics and durability of the photoreceptor according to the first embodiment, the irradiation condition is preferably set to an acceleration voltage of 250 kV or less, and 150 kV or less. Is more preferred. Further, the irradiation dose is preferably in the range from 10 kJ / kg to 1000 kJ / kg, and more preferably in the range from 30 kJ / kg to 500 kJ / kg.
[0072]
If the accelerating voltage is higher than the upper limit of the above-mentioned range, damage to the photoconductor characteristics due to electron beam irradiation, that is, so-called damage, tends to increase. If the irradiation dose is less than the lower limit of the above range, curing tends to be insufficient. In addition, if the dose is large, the photoreceptor characteristics are likely to deteriorate, and from this viewpoint, it is desirable to select the dose from the above range.
[0073]
In addition, as a compound for the surface layer which can be cured by polymerization or crosslinking, it is unsaturated in the molecule from the viewpoint of high reactivity, high reaction rate, and high hardness achieved after curing. Those containing a polymerizable functional group are preferred.
[0074]
Further, among the molecules having an unsaturated polymerizable functional group in the molecule, a compound having an acryl group, a methacryl group and a styrene group is particularly preferable.
[0075]
The compound having an unsaturated polymerizable functional group according to the first embodiment is roughly classified into a monomer and an oligomer depending on the state of repetition of the structural unit. The monomer refers to a monomer having no repeating structural units having an unsaturated polymerizable functional group and having a relatively small molecular weight. On the other hand, the oligomer is a polymer in which the number of repeating structural units having an unsaturated polymerizable functional group is about 2 to 20. Further, a so-called macronomer in which an unsaturated polymerizable functional group is bonded only to the terminal of the polymer or oligomer can be used as the curable compound for the surface layer according to the first embodiment.
[0076]
Further, in the compound having an unsaturated polymerizable functional group according to the first embodiment, it is more preferable that the compound employs a charge transport compound in order to satisfy a charge transport function required as a surface layer. Among these charge transport compounds, an unsaturated polymerizable compound having a hole transport function is more preferable.
[0077]
[Electrophotographic photoreceptor]
Next, the photosensitive layer of the electrophotographic photosensitive member according to the first embodiment of the present invention will be described.
[0078]
That is, as the support of the electrophotographic photoreceptor, any conductive material may be used. Specifically, for example, a metal such as aluminum, copper, chromium, nickel, zinc, and stainless steel, or an alloy thereof is drum-coated. Or formed in sheet form, laminated metal foil such as aluminum and copper on plastic film, evaporated aluminum, indium oxide and tin oxide on plastic film, coated with conductive material alone or with binder resin Thus, a metal provided with a conductive layer, a plastic film, paper, or the like can be given.
[0079]
Further, in the first embodiment of the present invention, an undercoat layer having a barrier function and an adhesive function can be provided on the surface of the conductive support.
[0080]
The undercoat layer is used to improve the adhesiveness of the photosensitive layer, improve the coating properties, protect the support, cover defects on the support, improve the charge injection property from the support, or protect the photosensitive layer against electrical breakdown. It is a layer formed for.
[0081]
Materials for the undercoat layer include polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide, N-methoxymethylated 6 nylon, copolymer nylon, glue and Gelatin or the like can be used. These materials are dissolved in a suitable solvent and applied to the surface of the support. The undercoat layer preferably has a thickness of 0.1 to 2 μm.
[0082]
When the photoreceptor of the present invention is a function-separated type photoreceptor, a charge generation layer and a charge transport layer are laminated. Examples of the charge generating substance used in the charge generating layer include selenium-tellurium (Se-Te), pyripium, thiapyrylium-based dyes, or various types of central metals and crystals, specifically, for example, α, β, γ, ε, And phthalocyanine compounds having a crystal form such as X type, anthantrone pigments, dibenzopyrene quinone pigments, pyranthrone pigments, trisazo pigments, disazo pigments, monoazo pigments, indigo pigments, kunacridone pigments, asymmetric quinocyanine pigments, quinocyanines and amorphous silicon Can be mentioned.
[0083]
In the case of a function-separated type photoreceptor, the charge generation layer contains a charge generation material together with a binder resin and a solvent in an amount of 0.3 to 4 times as much as a homogenizer, an ultrasonic dispersion, a ball mill, a vibration ball mill, a sand mill, an attritor and It is dispersed well by means such as a roll mill, applied with a dispersion, and dried, or formed as a film of a single composition such as a deposited film of a charge generating substance. Here, the curtain pressure of this electrification generating layer is typically 5 μm or less, and preferably 0.1 to 2 μm.
[0084]
Examples of the case of using a binder resin include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylates, methacrylates, vinylidene fluoride, and trifluoroethylene, and polyvinyl alcohol. , Polyvinyl acetal, polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melanin resin, silicon resin, epoxy resin and the like.
[0085]
The hole transporting compound having an unsaturated polymerizable functional group according to the first embodiment can be used as a charge transporting layer on the above-described charge generating layer. Alternatively, a charge transport layer composed of a charge transport layer and a binder resin may be formed on the charge generation layer, and then used as a surface protective layer.
[0086]
When a hole-transporting compound is used as the surface protective layer, the underlying charge-transporting layer is formed of a suitable charge-transporting substance, for example, a heterocyclic ring such as poly-N-vinylcarbazole or polystylanthracene or a condensed polycyclic aromatic ring. Or a heterocyclic compound such as pyrazoline, imidazole, oxadol, triazole, or carbazole; a triarylamine derivative such as triphenylamine; a phenylezine amine derivative; an N-phenylcarbazole derivative; a stilbene derivative; a hydrazone derivative; The low molecular compound of the above can be formed by applying a solution dispersed or dissolved in a solvent together with a suitable binder resin that can be selected from the above-described resin for the charge generation layer and drying by applying the above-mentioned known method. .
[0087]
In this case, the ratio of the charge transporting material to the binder resin is preferably such that the weight of the charge transporting material is in the range of 30 to 100 when the total weight of both is 100, and more preferably 50 to 100. It is preferable to select appropriately within the range.
[0088]
If the weight of the charge transporting material in the charge transporting layer is smaller than these ranges, the charge transporting ability decreases, and problems such as a decrease in sensitivity and an increase in residual potential occur. Also in this case, the thickness of the photosensitive layer is in the range of 5 to 30 μm. The thickness of the photosensitive layer at this time is the sum of the respective thicknesses of the charge generation layer, the charge transport layer, and the surface protective layer.
[0089]
In any case, the method of forming the surface layer is generally to apply a solution containing the hole transporting compound, and then polymerize or cure the solution. Note that it is also possible to form a surface layer by using a solution which is dispersed or dissolved in a solvent again after obtaining a cured product by reacting a solution containing a hole transporting compound in advance.
[0090]
Further, as a method for applying the above-mentioned solution, dip coating, spray coating, curtain coating, spin coating, and the like are known. From the viewpoint of efficiency / productivity, a dip coating method is preferable as a method of applying the solution. Note that other known film forming methods such as vapor deposition and plasma processing can be appropriately selected.
[0091]
In the surface protective layer according to the first embodiment of the present invention, conductive particles can be mixed. Examples of the conductive particles include metals, metal oxides, and carbon black.
[0092]
The metal as these conductive particles, specifically, aluminum, zinc, copper, chromium, nickel, stainless steel and silver can be mentioned, further, as the conductive particles, these metals are plastic particles Examples thereof include those deposited on the surface.
[0093]
Further, specifically, metal oxides as conductive particles include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony-doped tin oxide and antimony. Doped zirconium oxide.
[0094]
In addition, these metal oxides can be used alone or in combination of two or more. When two or more kinds are combined, they can be simply mixed, and a solid solution or fusion can be applied.
[0095]
In addition, the average particle size of the conductive particles used in the first embodiment of the present invention is preferably 0.3 μm or less, more preferably 0.1 μm or less, from the viewpoint of the transparency of the protective layer. Is desirable. Further, in the first embodiment, it is particularly preferable to use a metal oxide from the viewpoint of transparency and the like in the above-described material of the conductive particles.
[0096]
Further, the ratio of the conductive metal oxide particles in the surface protective layer is one of the factors directly determining the resistance of the surface protective layer. Therefore, the specific resistance of the protective layer is 10 ⁸ -10 ¹³ Ωm (10 ¹⁰ -10 ^Fifteen Ωcm).
[0097]
Further, in the first embodiment, the surface layer may contain fluorine atom-containing resin particles. Examples of the fluorine atom-containing resin particles include a tetrafluoroethylene resin, a trifluorinated ethylene resin, a hexafluoroethylene propylene resin, a vinyl fluoride resin, a vinylidene fluoride resin, a difluorinated ethylene chloride resin, and the like. It is preferable that at least one or more types are appropriately selected from copolymers.
[0098]
As the above-mentioned fluorine atom-containing resin particles, particularly, a tetrafluoroethylene resin and a vinylidene fluoride resin are preferable. The molecular weight and particle size of the resin particles can be appropriately selected, and are not necessarily limited to the above-described molecular weight and particle size.
[0099]
The proportion of the fluorine atom-containing resin in the surface layer is typically from 5 to 70% by weight, and preferably from 10 to 60% by weight, based on the total mass of the surface layer. If the proportion of the fluorine atom-containing resin particles is more than 70% by weight, the mechanical strength of the surface layer tends to decrease, and if it is less than 5% by weight, the releasability of the surface layer surface and the wear resistance of the surface layer This is because abrasion and scratch resistance may be insufficient.
[0100]
In the first embodiment of the present invention, additives such as a radical scavenger and an antioxidant may be added to the surface layer in order to further improve dispersibility, binding properties and weatherability. It is possible. In the first embodiment, the thickness of the surface protective layer is preferably in the range of 0.2 to 10 μm, and more preferably in the range of 0.5 to 6 μm.
[0101]
The wear amount of the surface of the photoreceptor as the image carrier used in the first embodiment is 2 mg or less in a Taber abrasion tester, but according to the knowledge of the present inventors, the wear amount is 6 mg or less. If there is, it is possible to obtain a sufficient effect.
[0102]
The test method of the above Taber abrasion test is as follows. A sample is mounted on a sample table of a Taber abrasion tester (YSS Taber, manufactured by Yasuda Seisakusho), and wrapping tape (manufactured by Fuji Film, product name : C2000) is applied to each of the rubber wear wheels (CS-0), and a load of 4.9 N (500 gf) is applied, and the weight loss of the sample after rotating 1000 times is measured by a precision balance. .
[0103]
[Charging]
Next, a charging roller as a charging unit according to the first embodiment will be described. That is, the charging roller 3 as a flexible contact charging member, which is a charging unit in the first embodiment, is formed by providing a medium resistance layer of rubber or foam on a cored bar.
[0104]
The medium resistance layer is formulated with a resin such as urethane, for example, conductive particles such as carbon black, a sulphidating agent or a foaming agent, and is formed in a roller shape on a cored bar, and the surface is polished. .
[0105]
Here, it is important that the charging roller 3 as a contact charging member functions as an electrode. That is, it is necessary to have a sufficiently low resistance to ensure sufficient contact with the member to be charged by providing elasticity and to charge the moving member to be charged.
[0106]
On the other hand, it is necessary to prevent voltage leakage when a low withstand voltage defect site such as a pinhole is present in the charged body. When a photoreceptor for electrophotography is used as a member to be charged, it is necessary to use 10 ⁴ -10 ⁷ A resistance of about Ω is desirable. In the first embodiment, 10 ⁶ Use a Ω resistor.
[0107]
If the hardness of the charging roller 3 is too low, the shape is not stable, so that the contact property with the member to be charged is deteriorated. If the hardness is too high, it is difficult to secure the charging nip portion a with the member to be charged. In addition, the microscopic contact with the surface of the member to be charged is deteriorated. Therefore, the hardness of the charging roller 3 is preferably in a range of 25 degrees or more and 60 degrees or less in Asker C hardness, and is set to, for example, 50 degrees in the first embodiment.
[0108]
The material of the charging roller 3 is not limited to an elastic foam, but may be carbon black or metal oxide for adjusting the resistance to EPDM, urethane, NBR, silicone rubber, or IR. And a foamed material of these materials. Note that the resistance can be adjusted using an ion-conductive material without dispersing the conductive substance.
[0109]
The charging roller 3 is disposed in such a manner that a pressing force against elasticity is pressed against the image carrier 2 as a member to be charged at 19.6 N (2 kgf). In the first embodiment, a charging portion having a width of several mm is formed.
[0110]
The resistance value of the charging roller 3 is measured as follows.
[0111]
That is, the image carrier 2 of the printer is replaced with an aluminum drum. Thereafter, a voltage of 100 V is applied between the aluminum drum and the metal core 8h of the charging roller 3. Then, the resistance value of the charging roller 3 is obtained by measuring the value of the current flowing at this time.
[0112]
The resistance value of the charging roller 3 according to the first embodiment thus determined is 5 × 10 ⁶ Ω. The measurement of the resistance was performed at an environment of a temperature of 25 ° C. and a humidity of 60%.
[0113]
Further, the above-described charging roller 3 rotates following the rotation of the image carrier 2. The charging roller 3 is controlled at a constant current of 1.15 kHz and a total current of 1750 μA from a charging high-voltage power supply, and the photoconductor potential is determined by the superposed DC bias.
[0114]
[Developer]
The developer used in the image forming apparatus according to the first embodiment is a two-component developer that is a mixture of a non-magnetic polymer toner generated by a polymerization method and a resin magnetic carrier.
[0115]
The T / D ratio of this developer is 8%. As the resin magnetic carrier, (4π) ^-1 × 10 ⁶ The magnetization intensity in A / m (1 kOe) magnetism is 4π × 10 ^-2 Wb / m ² (100 emu / cm ³ ), The number average particle size is 40 μm, and the specific resistance is 10 ¹¹ Ωm (10 ¹³ Ωcm).
[0116]
In general, the polymerization toner has a higher degree of sphericity than the pulverized toner. The spherical degree of the shape of the toner particles is expressed by using shape factors SF-1 and SF-2 calculated from the following equation (1). That is, the toner shape factors SF-1 and SF-2 are randomly sampled from 100 toner images using Hitachi FE-SEM (S-800), and the image information is obtained by an image analyzer (manufactured by Nireco). Luzex3) and is calculated from the following equation (1).
[0117]
(Equation 1)

In the formula (1), AREA is the toner projection area, MXLNG is the absolute maximum length (diameter of toner particles) of the toner, and PERI is the peripheral length of the toner particles.
[0118]
Among these toner shape factors, SF-1 indicates a spherical degree. That is, when the shape factor SF-1 is 100, the toner is a true sphere. When the shape factor SF-1 is in the range of 100 to 140, the toner is substantially spherical. When the shape factor SF-1 is larger than 140, the toner gradually changes from a substantially spherical shape to an irregular shape as the numerical value increases.
[0119]
On the other hand, the shape factor SF-2 indicates the degree of unevenness of the toner particle surface. That is, when the shape factor SF-2 is 100 to 120, the surface of the toner is smooth. When the shape factor SF-2 is larger than 120, the surface of the toner becomes significantly uneven.
[0120]
In order to maintain high transfer efficiency, the polymerized toner used in the image forming apparatus according to the first embodiment has an average particle diameter of 6 μm to 10 μm, a shape factor SF-1 of 100 to 140, and a shape factor SF- A substantially spherical toner having a number 2 of 100 to 120 is desirable.
[0121]
The toner used in the first embodiment is manufactured by a polymerization method. Then, silica, titanium oxide, or the like is externally added to the toner in order to stabilize the performance to be charged against environmental fluctuations and improve the fluidity.
[0122]
Further, the polymerized toner used in the image forming apparatus according to the first embodiment has a higher degree of sphericity and has no variation in size as compared with the conventional amorphous pulverized toner, and therefore has a higher self-lubricating property. . As a result, the toner is likely to slip through the contact portion of the cleaning blade 8a, and cleaning failure is likely to occur.
[0123]
Further, since the polymerized toner has a high self-lubricating property, the shear strength between the toners becomes small, and the shape of the surface of the photosensitive drum 2 has a greater influence on the cleaning performance of the cleaning blade 8a than the pulverized toner.
[0124]
[Cleaning device]
Therefore, the inventor has devised the cleaning device according to the first embodiment. Next, the cleaning device will be described. FIG. 2 shows a cleaning device according to the first embodiment.
[0125]
As shown in FIG. 2, the cleaning device 8 according to the first embodiment includes a cleaning blade 8a as a cleaning member, a toner collecting sheet 8b, a waste toner collecting container 8c, a cleaning auxiliary brush 8d as a cleaning auxiliary member, and a scraper. It has a brush scraper 8e as a member, a sheet metal 8f, a partition wall 8k, and a toner storage section 8j. The cleaning blade 8a is supported by a sheet metal 8f. Further, the partition wall 8k is installed almost directly below the brush scraper 8e.
[0126]
Next, the behavior of the toner remaining on the image carrier will be described.
[0127]
First, the toner remaining on the surface of the image carrier 2 after the primary transfer is removed from the image carrier 2 by the cleaning blade 8a and the cleaning auxiliary brush 8d constituting the cleaning device 8.
[0128]
Next, the toner removed from the cleaning blade 8a falls as it is and falls on the cleaning auxiliary brush 8d. The toner that has fallen on the cleaning auxiliary brush 8d moves with the rotation of the cleaning auxiliary brush 8d, and is peeled off from the cleaning auxiliary brush 8d by the brush scraper 8e.
[0129]
The stripped toner falls and is partially stored in the toner storage unit 8j as shown by the solid line arrow in FIG. 2 by the partition wall 8k, and the remaining part is the waste toner collection container as shown by the broken line arrow. 8c.
[0130]
Further, the toner scraped from the image carrier 2 by the cleaning auxiliary brush 8d is also scraped by the brush scraper 8e with its own rotation. A part of the scraped toner is stored in the toner storing section 8j, and the remaining part is stored in the waste toner collecting container 8c.
[0131]
Further, the toner adhering to the surface of the cleaning auxiliary brush 8d is once scraped off by the brush scraper 8e of the cleaning auxiliary brush 8d, and the toner stored in the toner storing portion 8j is again scooped up and carried on the surface. .
[0132]
Thereafter, the brush scraper 8e again rubs the surface of the image carrier 2 to diffuse and scrape the transfer residual toner on the image carrier 2 with the brush. At the same time, the toner picked up from the toner storage section 8j is re-applied to the image carrier 2, and the toner is supplied to the cleaning blade 8a.
[0133]
In this way, the toner scraped off on the surface of the image carrier is once peeled off from the cleaning auxiliary brush 8d by the brush scraper 8e, and the toner is held on the brush fibers by scooping up the brush again and supplied to the image carrier 2. By doing so, continuous rubbing with the image carrier due to the rotation of the brush is eliminated, and damage to the image carrier, the toner, and the brush can be prevented.
[0134]
Further, when the image ratio is large and the transfer residual toner is large, or when the developed toner without being transferred reaches the cleaner due to a paper jam or the like, a scraping action by the brush works.
[0135]
That is, a large amount of toner on the surface of the image carrier 2 serving as the image carrier is scraped off, and excess toner attached to the surface of the cleaning auxiliary brush 8d is scraped off by the brush scraper 8e. Then, a part of the toner is stored in the toner storage unit 8j, and a large amount of the remaining toner is collected in the collection container 8c.
[0136]
As described above, most of the toner remains on the image carrier 2, and if this state continues, the amount of toner supplied to the toner storage unit 8j increases. Therefore, the height of the partition wall 8k is set to 0.5 to 5.0 mm, preferably 1.0 to 3.0 mm, and more preferably 1.5 to 2.0 mm. Then, when the upper surface of the toner stored in the toner storage section 8j exceeds the upper end of the partition wall 8k, the toner automatically overflows and is collected in the waste toner collecting container 8c.
[0137]
The height of the partition wall 8k is a numerical value to be appropriately optimized depending on the height of the lower jaw of the cleaning device 8 to which the toner collecting sheet 8b is fixed, the amount of toner consumed by the brush, and the like.
[0138]
When the image ratio is small, the cleaning auxiliary brush 8d scoops up the waste toner in the toner storage section 8j, is held by the brush fibers, comes into contact with the image carrier, and supplies the waste toner to the image carrier. Is done.
[0139]
As a result, the waste toner is supplied to the contact portion between the cleaning blade 8a and the image carrier 2, so that the sliding property between the image carrier and the cleaning blade 8a is maintained, and the blade squeal and the curl are prevented.
[0140]
Further, the amount of waste toner applied to the image carrier 2 by the cleaning auxiliary brush 8d changes the amount of toner on the drum from a solid white image to an untransferred solid black image. The present inventor has studied and found that the amount of waste toner applied was 0.05 to 0.3 kg / m. ² (0.05-0.3mg / mm ² ) Is suitable, and preferably 0.1 to 0.2 kg / m ² (0.1-0.2mg / mm ² ) Was found to be good.
[0141]
Further, in order to stabilize the amount of application to the image carrier 2 from an initial stage, it is necessary to previously apply the toner to the cleaning auxiliary brush 8d or to replenish the toner to the toner storage unit 8j in advance. desirable.
[0142]
At this time, the toner to be applied or replenished may be a replenishing agent or waste toner to be replenished for development. It is also possible to supply untransferred toner by a method such as so-called blackish formation.
[0143]
Here, the cleaning auxiliary brush 8d is configured such that conductive fibers are planted on a base cloth and wound around a φ6 cored bar 8h to form a φ16 brush. The core metal 8h is grounded. Here, in the first embodiment, the conductive fibers have a thickness of 7.0 × 10 ^-5 kg / m (0.7Tex) nylon conductive yarn, fiber density 93mm ^-2 (1mm ² (93 per contact) is formed into a sheet, and is spirally wound so as to ensure conduction with the cored bar 8h.
[0144]
As for the condition of the brush, various materials such as nylon, rayon, polyester, and acrylic can be used as the material. The weave of this brush is typically 0.3 × 10 ^-6 2.2 x 10 for kg / m or more ^-6 kg / m or less, and even within this range, 0.4 × 10 ^-6 kg / m or more 1.1 × 10 ^-6 kg / m or less is preferable.
[0145]
The fiber density of the brush is typically 15.5 mm. ^-2 More than 310mm ^-2 Below (1mm ² 15.5 or more and 310 or less), preferably 46.5 mm ^-2 More than 155mm ^-2 Below (1mm ² 46.5 or more per line and 155 or less per line).
[0146]
As shown in FIG. 2, the cleaning auxiliary brush 8d is disposed on the upstream side of the cleaning blade 8a along the rotation direction of the image carrier 2, and the penetration amount α into the image carrier 2 becomes 1 mm. And are rotatably disposed.
[0147]
Further, as shown in FIG. 3, the image carrier 2 is rotationally driven at a speed of 60 rpm in a direction indicated by an arrow B which is rotated in the opposite direction. That is, the image carrier 2 and the cleaning auxiliary brush 8d are mutually rotated in the same direction at the contact portion.
[0148]
At this contact portion, the transfer residual toner on the image carrier 2 after the primary transfer is scraped off. Alternatively, the adhesion of the transfer residual toner to the image carrier 2 is weakened, thereby facilitating the cleaning by the cleaning blade 8a described later.
[0149]
Further, at the contact portion, even if the image ratio is small and the transfer residual toner is scarcely present, as described above, the cleaning auxiliary brush 8d allows the waste toner to be supplied to the cleaning blade 8a by an appropriate amount. Will be fed. For this reason, it is possible to suppress blade squeal and turnover.
[0150]
Further, when the cleaning operation is repeatedly performed, the cleaning auxiliary brush 8d causes clogging of the brush fibers to form a toner roll, resulting in a reduction in cleaning performance. In order to prevent this, a brush scraper 8e, which is a member for scraping off the toner accumulated in the brush fibers, is provided.
[0151]
As shown in FIG. 3, in the first embodiment, a flexible sheet made of polyethylene terephthalate (PET) having a thickness of, for example, 0.1 mm is attached to a sheet metal as the brush scraper 8e. The free length is 2 mm, and the penetration amount β into the cleaning auxiliary brush 8d is 1.0 mm.
[0152]
Here, the inventor of the present invention focused on the relationship between the amount of intrusion α and the amount of intrusion β and conducted intensive studies. As a result, the inventor found that a relationship satisfying α ≧ β was necessary.
[0153]
That is, if the brush penetration amount β into the brush scraper 8 e is larger than the brush penetration amount α into the image carrier 2, the scraping action on the brush by the scraper becomes too strong. This makes it difficult to ensure a sufficient amount of toner applied to the image carrier 2.
[0154]
Also, depending on the material, thickness, and free length of the scraper sheet, if the penetration amount β is set too large, the scraper sheet will be turned up due to durability. Further, if the scraping action is too strong, there is a possibility that a sufficient amount of coating on the image carrier cannot be secured.
[0155]
Then, the present inventor has conducted a study based on the first embodiment, and has found that when the intrusion amount β is set to 2.5 mm or more in the configuration, the curling occurs.
[0156]
Further, when the scraper sheet of the brush scraper 8e is made of a material having high hardness, for example, when a sheet metal having a thickness of 1 to 2 mm is used, the brush falls down on the brush side, and the outer diameter of the brush becomes small. This causes a problem that the original brush function cannot be performed.
[0157]
Therefore, it is necessary to select and set the brush scraper 8e in consideration of the above.
[0158]
As the scraper sheet of the brush scraper 8e, any material may be used as long as it has a property of bending to some extent. For example, a high-density polyethylene sheet having high slidability can be used with emphasis on durability.
[0159]
Further, as the scraper sheet, it is also possible to use a sheet in which the material itself has releasability and is formed into a sheet shape, or a sheet having a high release coated silicone coat on the surface. This makes it possible to prevent toner sticking to the sheet, which may occur particularly when the cleaning auxiliary brush 8d is used at high speed.
[0160]
On the other hand, the cleaning blade 8a is made of polyurethane rubber integrally held at the tip of the sheet metal 8f. Then, as shown in FIG. 4, the cleaning blade 8a is in contact with the image carrier 2 under the conditions of a predetermined penetration amount δ and a set angle θ.
[0161]
In the first embodiment, as a result of intensive studies by the present inventors, the rubber hardness of the cleaning blade 8a is typically 50 to 85 degrees (JISA), preferably 60 to 80 degrees (JISA). It was confirmed that the range was preferable. Therefore, in the first embodiment, the cleaning pressure is set to θ = 22 ° and δ = 1.0 using a cleaning blade 8a having a rubber hardness of 70 degrees (JISA), and the contact pressure against the image carrier 2 is reduced. It is about 39 N / m (40 g / cm).
[0162]
Here, in order to confirm the effect of the first embodiment, low-temperature low-humidity (temperature of 23 ° C. and 5% humidity), normal temperature and normal humidity (temperature of 23 ° C. and 60% humidity) and high-temperature high humidity (temperature of 30 ° C.) In each environment of 80% humidity, an endurance test was performed on 20,000 sheets by continuous printing, and an experiment was conducted to examine cleaning properties and other problems. In this durability test, 2,500 sheets were printed per day for eight consecutive days.
[0163]
As a result of the durability test, in the configuration of the first embodiment, no failure such as cleaning failure or blade squealing or curling occurred during the durability, and high quality image formation was performed throughout the life of the image carrier 2. It was confirmed that it was possible.
[0164]
After the durability test, the amount of application to the image carrier 2 by the cleaning auxiliary brush 8d was measured. As a result, the value initially set was almost maintained. Further, when the cleaning performance before and after the passage of the cleaning auxiliary brush at the time of cleaning the transfer residual toner was confirmed, the initial state was almost maintained. Thus, it was confirmed that the transfer residual toner can be reliably removed.
[0165]
(Second embodiment)
Next, a description will be given of a cleaning device in an image forming apparatus according to a second embodiment of the present invention.
[0166]
In the cleaning device according to the second embodiment, a sponge roller is used instead of the brush used in the first embodiment. Other configurations of the cleaning device according to the second embodiment are the same as those in the first embodiment, and thus description thereof is omitted. FIG. 2 is referred to for the drawings.
[0167]
The sponge roller according to the second embodiment is made of a sponge made of foamed polyurethane, foamed silicone, foamed EPDM, or the like. Specifically, for example, foamed polyurethane is prepared by mixing a main raw material mainly composed of a polyisocyanate prepolymer and a polyether-based polyol, and a low-viscosity mixed solution of a foam stabilizer obtained by dissolving silicone in an alkylbenzene solvent to prepare an adjustment solution. The urethane rubber sponge roller body is formed by reaction molding, and the roller body is manufactured by attaching a shaft to the roller body.
[0168]
The outer diameter of the sponge roller is, for example, 15.4 mm. The hardness of the sponge roller is 30 degrees (Asker C). Note that the hardness is typically 10 to 50 ° (Asker C), and preferably 20 to 40 °. This is because if the hardness of the sponge roller is less than 10 degrees, the rubbing force is insufficient, and if the hardness exceeds 50 degrees, the possibility of damaging the image carrier increases. It is.
[0169]
Further, the size of the cells on the surface of the sponge roller affects the scraping of the transfer residual toner on the surface of the image carrier 2 and the application of the waste toner. Therefore, the diameter of the cell is preferably from 0.1 to 100 μm, and more preferably from 1 to 10 μm. This is because if the diameter of the cell is less than 0.1 μm, the ability to scrape and apply is insufficient, while if the diameter of the cell exceeds 100 μm, toner clogging is likely to occur.
[0170]
The sponge roller is in contact with the image carrier at a penetration amount α of 0.7 mm and a linear pressure of 58.8 N / m (60 gf / cm).
[0171]
The sponge roller is rotatably disposed on the upstream side of the cleaning blade 8 a along the rotation direction of the image carrier 2, and rotates at a speed of 60 rpm in a direction indicated by an arrow B that is rotated in the opposite direction to the image carrier 2. Driven at speed. That is, the image carrier 2 and the cleaning auxiliary brush 8d are mutually rotated in the same direction at the contact portion.
[0172]
Further, the penetration amount β of the brush scraper 8e with respect to the sponge roller is set to 0.3 mm.
[0173]
With the above configuration, in order to confirm the effect of the cleaning device according to the second embodiment, low-temperature and low-humidity (temperature of 23 ° C. and 5% of humidity), normal temperature and normal humidity (temperature of 23 ° C. and 60% of humidity), and An endurance test was performed in each environment of high temperature and high humidity (temperature of 30 ° C and humidity of 80%). That is, an endurance test was performed on 10,000 sheets by continuous printing, and an experiment was conducted to check the cleaning property and other defects. In this durability test, 2500 prints were made per day, and the test was performed for four consecutive days.
[0174]
As a result of the endurance test, in the configuration of the cleaning device according to the second embodiment, through the endurance test, no failure such as poor cleaning or blade squealing or curling occurs, and the life of the image carrier 2 is maintained. It was confirmed that high quality image formation was possible.
[0175]
(Third embodiment)
Next, a cleaning device according to a third embodiment of the present invention will be described. FIG. 5 shows a cleaning device according to the third embodiment.
[0176]
As shown in FIG. 5, in the cleaning device 8 of the image forming apparatus according to the third embodiment, the lubricant 8m is brought into contact with the cleaning auxiliary brush 8d, and the surface of the image carrier 2 is contacted via the cleaning auxiliary brush 8d. It is configured to be applied.
[0177]
In this way, by smoothing the surface of the image carrier 2, movement such as chatter in the cleaning blade 8a can be particularly suppressed.
[0178]
Further, the cleaning effect can be further improved even with the spherical toner and the high-hardness photosensitive drum used in the third embodiment.
[0179]
Further, by uniformly applying a thin film of the lubricant 8 m on the surface of the image carrier 2, the electrostatic adhesion of the toner and the external additive can be reduced. Here, as the lubricant 8m, a metal soap such as zinc stearate is used, and a hardness specified by JIS pencil hardness is used.
[0180]
The metal soap is made of powder before solidification, and has an apparent specific gravity of 0.50 to 0.75 g / mml. The metal soap is solidified by being subjected to a melting treatment or a cooling treatment, and is adjusted to have a JIS pencil hardness of B. In addition, as the metal soap, in addition to zinc stearate, relatively higher fatty acids such as iron stearate, tin stearate, magnesium palmitate, calcium palmitate, manganese oleate, and lead oleate can be used. It is.
[0181]
The lubricant 8m is cut and worn by the application and supply operations to the image carrier 2 by the cleaning auxiliary brush 8d in accordance with the image forming process over time, and the shape changes, and the amount of the lubricant gradually decreases compared to the initial stage. I do.
[0182]
At this time, in the related art, a fixing member (not shown) of the lubricant 8m is constantly pressed against the cleaning auxiliary brush 8d from the back by a pressing means such as a spring, and the lubricant 8m is uniformly applied with time. .
[0183]
In order to confirm the effect of improving the slipperiness by applying the lubricant composed of zinc stearate, a paper passing test was performed on 10,000 sheets, and the following results were obtained by comparing the contact angle with water and the slipperiness.
[0184]
In the absence of the lubricant, the contact angle was 50 ° and the slip property was 1.1, and in the case of the lubricant, the contact angle was 60 ° and the slip property was 1.0. Here, the slipperiness is measured by a slipperiness tester manufactured by Haydon Co., Ltd., and the slipperiness of an object to be measured when the slipperiness of polyethylene terephthalate (PET) is set to 1 in terms of a PBT ratio. It is shown. The smaller the value of the slip property, the better the slip property.
[0185]
Furthermore, in order to confirm the effect of the third embodiment, low-temperature low-humidity (temperature of 23 ° C. and 5% humidity), normal temperature and normal humidity (temperature of 23 ° C. and 60% humidity), and high-temperature high humidity (temperature of 30 ° C. and 80% humidity) %), An endurance test of 100,000 sheets was performed by continuous printing, and an experiment was conducted to check the cleaning property and other problems. The durability test was carried out for 5,000 sheets per day and continuously for 20 days.
[0186]
As a result of the endurance test, in the configuration of the third embodiment, high-quality image formation is performed throughout the life of the image carrier 2 without causing any trouble such as cleaning failure or blade squeal or curling during the endurance test. Was able to do.
[0187]
When the amount of application to the image carrier 2 by the cleaning auxiliary brush 8d was measured after the durability test, the value initially set was almost maintained. Further, when the cleaning performance before and after the passage of the cleaning auxiliary brush at the time of cleaning the transfer residual toner was confirmed, the initial state was almost maintained. From these facts, it was confirmed that the transfer residual toner can be reliably removed.
[0188]
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.
[0189]
For example, the molecular weights, particle diameters, and numerical values described in the above embodiments are merely examples, and different molecular weights, particle diameters, and numerical values may be used as needed.
[0190]
In the present embodiment, a full-color copying machine is cited as an example of the configuration of the image forming apparatus. However, the present invention is not limited to this, and includes a developer cleaning device such as a printer, a facsimile, and a monochrome copying machine. It is possible to apply to things.
[0191]
Further, for example, in the above-described first embodiment, a spherical toner formed by a polymerization method is used from the viewpoint of good transferability, but is not necessarily limited to a toner manufactured by a polymerization method. It is also possible to use a toner prepared by the mechanical pulverization and classification method and subjected to a thermal or mechanical post-treatment and rounded.
[0192]
Further, for example, in the above-described third embodiment, the rotation directions of the cleaning auxiliary member and the image carrier are set to be opposite to each other, and the same direction is set at the contact portion. However, the rotation direction may be set to be opposite. .
[0193]
Further, for example, in the above-described third embodiment, the toner scraped from the cleaning auxiliary member and the cleaning member is configured to be collected in the toner pool by natural fall, but the toner once peeled off from the image carrier is removed. It is also possible to adopt a configuration in which after collecting all in the waste toner collecting container, a part of it is again applied to the image carrier 2 via the cleaning auxiliary member. In this case, the same effect is obtained. be able to.
[0194]
【The invention's effect】
As described above, according to the present invention, when a high-hardness photoconductor and a developer having a small particle diameter (particularly, a spherical developer), which are difficult to clean, are used, the cleaning unit is provided with at least a cleaning member. And a cleaning auxiliary member provided on the upstream side in the rotation direction of the image carrier with respect to the cleaning member, and a waste developer storage section, wherein at least one of the cleaning member and the cleaning auxiliary member A part of the waste developer scraped from the surface of the image carrier is fed to the developer storing section, and the remaining scraped transfer residual developer is fed to the toner collecting container to store the developer. The developer sent to the image forming section is applied to the image carrier between the cleaning assisting member and the cleaning member via the cleaning assisting member. Squeal faulty cleaning and blade over, turn-up can be prevented occurrence of, it is possible to perform stable cleaning.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing a schematic configuration of a cleaning device according to the first embodiment of the present invention.
FIG. 3 is a partially enlarged view showing a cleaning auxiliary brush according to the first embodiment of the present invention.
FIG. 4 is a partially enlarged view for explaining a penetration amount δ and a set angle θ of the cleaning blade according to the first embodiment of the present invention with respect to an image carrier.
FIG. 5 is a sectional view showing a schematic configuration of a cleaning device according to a third embodiment of the present invention.
[Explanation of symbols]
1 Image forming apparatus
2 Image carrier
3 charging roller
4 Laser oscillator
5 Laser beam
6. Rotary developing device
6y first developing device
6m second developing device
6c Third developing device
6k Fourth developing device
7 Intermediate transfer member
7a, 7b transcription site
7c High voltage power supply
8 Cleaning device
8a Cleaning blade
8b Toner collection sheet
8c Waste toner collection container
8d Cleaning auxiliary brush
8e brush scraper
8f sheet metal
8h core metal
8j Toner storage unit
8k bulkhead
8m lubricant
9 cassettes
10 Pickup roller
11 Registration roller pair
12 Transfer belt
12a bias roller
12b tension roller
12c High voltage power supply
13 Intermediate transfer member cleaning device
14 Fixing machine
15 Discharge roller pair
S recording medium

Claims (13)

An image carrier;
Charging means for charging the image carrier,
Exposure means for forming a latent image by performing image exposure on the image carrier charged by the charging means,
Developing means for developing the latent image as an image,
Cleaning means for cleaning the image carrier after the developed image is transferred,
Having a developer collection container for storing the transfer residual developer,
The surface polishing amount of the image carrier is 2 mg or less;
The cleaning unit includes at least a cleaning member, a cleaning auxiliary member, and a waste developer storage unit that stores a part of the waste developer removed from the surface of the image carrier by the cleaning member or the cleaning auxiliary member. Having
A part of the waste developer removed from the surface of the image carrier by at least one of the cleaning member or the cleaning auxiliary member in contact with the image carrier is supplied to the waste developer storage section, and the waste development is performed. The remaining transfer developer remaining in the developer is supplied to the developer collection container,
An image forming apparatus, wherein the developer supplied to the waste developer reservoir is applied to the image carrier via the cleaning auxiliary member. 2. The image forming apparatus according to claim 1, wherein the cleaning auxiliary member is provided upstream of the cleaning member in a rotation direction of the image carrier. The surface layer of the photosensitive layer in the image carrier is formed of an electrophotographic photosensitive member containing a compound cured by polymerization or crosslinking of a hole transporting compound having at least a chain polymerizable functional group. The image forming apparatus according to claim 1. A compound obtained by curing the image carrier by polymerizing or crosslinking a hole transporting compound having at least a chain polymerizable functional group by radiation (electron beam) irradiation on the surface layer of the photosensitive layer in the image carrier. 4. The image forming apparatus according to claim 3, wherein said image forming apparatus comprises an electrophotographic photosensitive member. 5. The image forming apparatus according to claim 1, wherein a developer is attached to or replenished to at least one of the cleaning auxiliary member and the developer storage unit in advance. 5. apparatus. 5. The image forming apparatus according to claim 4, wherein at least one of the cleaning member and the cleaning auxiliary member is provided with a scraper member for scraping off and removing the attached developer. 7. The image forming apparatus according to claim 5, wherein a lubricant is contact-applied to the auxiliary cleaning member, and the lubricant is applied to the image carrier via the auxiliary cleaning member. 7. The relationship of .alpha..gtoreq..beta. Is established between the amount .alpha. Of penetration of the cleaning auxiliary member into the image carrier and the amount .beta. Of penetration of the scraper member into the cleaning auxiliary member. Image forming device. 2. The image forming apparatus according to claim 1, wherein said cleaning member comprises a rubber blade having elasticity and contacting the image carrier. 10. The cleaning assisting member according to claim 1, wherein the cleaning assisting member comprises a fur brush having brush fibers having a weave of 0.2 × 10 ⁻⁶ kg / m or more and 3.3 kg / m or less. The image forming apparatus according to claim 1. 10. The image forming apparatus according to claim 1, wherein the surface cell structure of the cleaning assisting member comprises a sponge roller having a size of 0.1 μm or more and 100 μm or less. 4. The toner according to claim 1, wherein the developer is a toner, and the shape factor SF-1 of the toner is 100 or more and 150 or less, and the shape factor SF-2 of the toner is 100 or more and 140 or less. The image forming apparatus according to claim 11. 2. The image forming apparatus according to claim 1, wherein a photosensitive layer is provided on a surface of the image carrier, and a surface wear amount of the photosensitive layer in the image carrier is 6 mg or less.

Images