JP4743370B2

JP4743370B2 - Photosensitive drum, method of assembling the same, and image forming apparatus using the same

Info

Publication number: JP4743370B2
Application number: JP2001169275A
Authority: JP
Inventors: 慎一飯嶋
Original assignee: Mitsubishi Chemical Corp
Current assignee: Mitsubishi Chemical Corp
Priority date: 2001-06-05
Filing date: 2001-06-05
Publication date: 2011-08-10
Anticipated expiration: 2021-06-05
Also published as: JP2002365974A

Description

【０００１】
【発明の属する技術分野】
本発明は複写機やプリンタなどの電子写真装置に用いられる感光体ドラムとその組み立て方法及びそれを用いた画像形成装置に関する。
【０００２】
【従来の技術】
近年の電子写真装置の高解像度化、カラー化、小型化の推進により、感光体ドラムに対する高精度化要求がより高まってきている。
すなわち、感光体ドラムに曲がり（感光体ドラム自体が湾曲している状態）や軸ずれ（感光体ドラムの外周面中心と回転中心がずれている状態）があると、これら曲がりや軸ずれに起因する振れ回りにより、静電潜像形成時および転写時に、本来形成されるべき位置からの画像ずれが生じる。
より詳細に説明すると、レーザービームプリンタなどのようにポリゴンミラーを用いてレーザー走査を行なうものでは、静電潜像形成時、感光体ドラムの端部に近いほど斜めにレーザービームが入射するので、感光体ドラムに曲がりや軸ずれがあると、レーザービームの到達位置がドラム軸方向にずれる主走査方向ずれが生じる。また、感光体ドラムに曲がりや軸ずれがあると、感光体ドラムの回転中心から感光体ドラムの表面までの距離、すなわち、回転半径の違いにより、回転半径の小さい部位では感光体ドラム表面の露光系に対する移動速度が遅くなって静電潜像が詰まり、回転半径の大きい部位では感光体ドラム表面の露光系に対する移動速度が速くなって静電潜像が伸びる副走査方向ずれが生じる。
【０００３】
その結果、印刷された画像に歪みが生じる。特に、タンデム型と呼ばれる、複数の感光体ドラムを平行に並べて使用するカラー複写機の場合には、位置ずれ、色ずれとして顕著化する。
他にも、発光ダイオードを露光装置として使用するものでは、焦点距離が近いことから振れ回りによる画像ぼけが生じ易く、問題が大きい。
これらの理由から感光体ドラムの高精度化、特に、回転精度に対する高精度化が必要となる。
【０００４】
【発明が解決しようとする課題】
一方、図１に示すように、感光体ドラム１２は、筒体１４０２の表面に感光層１４０４が形成されたドラム本体１４と、ドラム本体１４の両端の嵌合穴１４０６に配設されるフランジ部材１６、１８とで構成されている。
前記フランジ部材１６、１８は嵌合穴１４０６に嵌め込まれ固定される環板部１６０２、１８０２と、フレーム側で支持される軸受部１６０４、１８０４と、環板部１６０２、１８０２の基端に位置して環板部１６０２、１８０２が嵌合穴１４０６に嵌め込まれる際にドラム本体１４（筒体１４０２）の端面１４０８に突き当たる環状の突き当て面１６０６、１８０６とを備え、また、一方のフランジ部材１６にはドラム本体１２を回転させるためのギヤ部１６０８が設けられている。
そして、フランジ部材１６、１８のドラム本体１４への取り付けは、フランジ部材１６、１８の環板部１６０２、１８０２がドラム本体１４の両端の嵌合穴１４０６に嵌め込まれ固定されることでなされる。
より詳細には、フランジ部材１６、１８の突き当て面１６０６、１８０６がドラム本体１４の端面１４０８に突き当たるまで、フランジ部材１６、１８の環板部１６０２、１８０２をドラム本体１４の両端の嵌合穴１４０６に圧入することで固定されている。
あるいは、ドラム本体１４の両端の嵌合穴１４０６の内周面に接着剤を塗布しておき、フランジ部材１６、１８の突き当て面１６０６、１８０６がドラム本体１４の端面１４０８に突き当たるまで、環板部１６０２、１８０２を嵌合穴１４０６に嵌め込むことで固定されている。
また、感光体ドラム１２のフレーム側への配設は、フランジ部材１６、１８の軸受部１６０４、１８０４がフレーム側で回転可能に支持されることでなされている。なお、フランジ部材１６、１８の軸受部１６０４、１８０４が穴状である場合にはフレーム側の軸を介して回転可能に支持され、軸受部１６０４、１８０４が軸状である場合にはフレームの軸受穴を介して回転可能に支持されることになる。
【０００５】
このように感光体ドラム１２は、１本のドラム本体１４と、２つのフランジ部材１６、１８から構成されているが、これらドラム本体１４とフランジ部材１６、１８をそれぞれ設計寸法どうりに加工することは加工精度上困難で、実際には、許容範囲内において加工誤差（製造誤差）を有している。
すなわち、ドラム本体１４について言えば、ドラム本体１４を構成する筒体１４０２は、多くの場合アルミ合金製であり、素材の偏肉や曲がりを合わせて数十ミクロンの振れ回りが既に存在しており、また、筒体１４０２各部位で微妙な内部応力差が存在するなどしていることから、生産性を高めた通常の加工精度では限界がある。
また、このような筒体１４０２の表面に設けられる感光層１４０４の厚さも、筒体１４０２の周方向において均一とは言い難く、厳密にはばらつきを有している。
また、筒体１４０２の両端の嵌合穴１４０６も、それらの中心とドラム本体１４の外周面とが高精度で一致しているとは限らず、この嵌合穴１４０６にフランジ部材１６、１８が固定され、フランジ部材１６、１８を介してドラム本体１４が回転することから、嵌合穴１４０６の中心とドラム本体１４の外周面中心とがずれている場合に振れ回りの原因となる。
【０００６】
また、フランジ部材１６、１８について言えば、多くの場合、フランジ部材１６、１８は合成樹脂製で型成形されており、許容範囲内において加工誤差（製造誤差）を有している。
すなわち、環板部１６０２、１８０２の中心と軸受部１６０４、１８０４との中心とはずれており、環板部１６０２、１８０２を嵌合穴１４０６に圧入固定する構造を採るものでは振れ回りの原因となる。
また、軸受部１６０４、１８０４の中心軸線は、突き当て面１６０６、１８０６を通る仮想平面に対して直交しておらず、傾斜しており、嵌合穴１４０６の内周面に接着剤を塗布しておき、突き当て面１６０６、１８０６がドラム本体１４の端面１４０８に突き当たるまで、環板部１６０２、１８０２を嵌合穴１４０６に嵌め込む構造を採るものでは、突き当て面１６０６、１８０６が基準面となることからやはり振れ回りの原因となる。
【０００７】
このようなドラム本体１４やフランジ部材１６、１８のさらなる高精度化も可能とは推察されるが、生産性を著しく阻害することから実現性は乏しい。
すなわち、感光体ドラム１２を構成する部材の精度をより一層高めて高精度化要求を満たす感光体ドラム１２を得ることは、感光体ドラム１２の単価や製造コスト等の点で現実問題として困難となる。
これらの不具合は、ドラム本体の長手方向の一方の端部のみにフランジ部材を設けた片持ち式の感光体ドラムの場合も同様である。
本発明は前記事情に鑑み案出されたものであって、本発明の目的は、ドラム本体やフランジ部材について実現性の乏しい高精度化を要求することなく、高精度化要求を満たせる感光体ドラムを提供することにある。
また、本発明の目的は、上記の感光体ドラムを簡単にかつ迅速に得ることができる感光体ドラムの組み立て方法を提供することにある。
さらに、本発明の目的は、上記の感光体ドラムを用いた画像形成装置を提供することにある。このような実状に鑑み、本発明者は特願２０００−１５５９７１にて感光体ドラムを高精度に組み立てる手法について発明したが、特にタンデムマシンの設計においては単品の高精度化とは別に各ドラムの偏心方向を管理することが一般的になされている。前記発明ではドラムとフランジ部材の偏心量を打ち消し合う方向に嵌め込むため、少しの位置ズレが生じても組立後の偏心方向が大きくずれ、偏心方向にバラツキを生じやすくなるという欠点があり、偏心方向を管理するうえで問題となるケースがあった。
【０００８】
【課題を解決するための手段】
前記目的を達成するため本発明の感光体ドラムは、ドラム本体の偏心方向と、フランジ部材の偏心方向とを互いの偏心量を増幅する方向にしてフランジ部材の環板部がドラム本体の嵌合穴に嵌め込まれ固定されていることを特徴とする。
また、本発明の感光体ドラムは、ドラム本体の偏心の方向と、フランジ部材の中心軸線の傾斜方向とをほぼ逆向きにしてフランジ部材の環板部がドラム本体の嵌合穴に嵌め込まれ、突き当て面がドラム本体の端面に突き当てられて固定されていることを特徴とする。
また、本発明の感光体ドラムの組み立て方法は、予めフランジ部材の偏心方向を求めておき、ドラム本体を、その軸心回りに回転させることができる回転装置上において前記ドラム本体の偏心方向を求め、ドラム本体の偏心方向を求めた後、ドラム本体を回転装置上において回転させ、ドラム本体の偏心方向を所定の方向に一致させ、前記所定の方向に対して各フランジ部材の偏心方向をほぼ同じ向きにして各フランジ部材の環板部をドラム本体の嵌合穴にそれぞれ嵌め込み固定するようにしたことを特徴とする。
また、本発明の感光体ドラムの組み立て方法は、予めフランジ部材の軸受部の中心軸線の傾斜方向を求めておき、ドラム本体を、その軸心回りに回転させることができる回転装置上において前記ドラム本体の偏心方向を求め、ドラム本体の偏心方向を求めた後、ドラム本体を前記回転装置上において回転させ、ドラム本体の偏心方向を所定の方向に一致させ、前記所定の方向に対して各フランジ部材の軸受部の中心軸線の傾斜方向をほぼ逆向きにして各フランジ部材の環板部をドラム本体の嵌合穴にそれぞれ嵌め込み、突き当て面をドラム本体の端面に突き当てて固定するようにしたことを特徴とする。
また、本発明の画像形成装置は、前記感光体ドラムを用いたことを特徴とする。
【０００９】
本発明の感光体ドラムによれば、ドラム本体の偏心量とフランジ部材の偏心量とが増幅されることにより感光体ドラムの組立後の偏心方向が安定し、バラツキガ少なくなるためドラムの偏心方向を管理しやすくなる。製造精度上の誤差を有するドラム本体とフランジ部材から高精度要求を満たす感光体ドラムが得られる。
また、本発明の感光体ドラムの組み立て方法によれば、ドラム本体の偏心方向の計測から、両端のフランジ部材の嵌め込み固定まで、一連の動作により連続的に行なうので、製造精度上の誤差を有するドラム本体とフランジ部材から、高精度要求を満たすの感光体ドラムを簡単にしかも短時間で得ることができる。
また、本発明の画像形成装置によれば、位置ずれや色ずれなどのような歪みやぼけのない明瞭な画像が得られる。
【００１０】
【発明の実施の形態】
以下、本発明の実施の形態に係る感光体ドラムをその組み立て方法と共に説明する。
図１を参照して説明すると、感光体ドラム１２を構成する個々の部材は従来技術で述べたものと同様である。
すなわち、感光体ドラム１２は、ドラム本体１４と２つのフランジ部材１６、１８とで構成されている。前記ドラム本体１４は、その長手方向の両端に嵌合穴１４０６が形成された筒体１４０２と、筒体１４０２の外周面に形成された感光層１４０４とで構成されている。前記各フランジ部材１６、１８は、それらの環板部１６０２、１８０２がドラム本体１４の両端の嵌合穴１４０６に嵌め込まれ固定されている。
【００１１】
前記筒体１４０２は多くの場合アルミ合金製であり、素材の偏肉や曲がりを合わせて数十ミクロンの振れ回りが既に存在しており、また、筒体１４０２各部位で微妙な内部応力差が存在している。
また、感光層１４０４の厚さも、筒体１４０２の周方向において厳密にはばらつきを有している。
すなわち、前記ドラム本体１４は許容範囲内において加工誤差（製造誤差）を有し、図２（Ａ）に示すように、両端の嵌合穴１４０６の中心Ｃ１に対してドラム本体１４の外周面の中心Ｃ２は偏心している。この場合、嵌合穴１４０６の中心Ｃ１から外周面の中心Ｃ２への方向をドラム本体１４の偏心方向Ｆ１と呼ぶ。
【００１２】
前記フランジ部材１６、１８は、嵌合穴１４０６に嵌め込まれ固定される環板部１６０２、１８０２と、フレーム側で支持される軸受部１６０４、１８０４と、環板部１６０２、１８０２が嵌合穴１４０６に嵌め込まれる際にドラム本体１４の端面１４０８に突き当たる環状の突き当て面１６０６、１８０６とを備え、フランジ部材１６、１８は合成樹脂製で型成形により形成されている。
すなわち、フランジ部材１６、１８は許容範囲内において加工誤差（製造誤差）を有し、図２（Ｂ）に示すように、軸受部１６０４、１８０４の中心Ｃ３に対して環板部１６０２、１８０２の中心Ｃ４は偏心している。この場合、軸受部１６０４、１８０４の中心Ｃ３から環板部１６０２、１８０２の中心Ｃ４への方向をフランジ部材１６、１８の偏心方向Ｆ２と呼ぶ。
【００１３】
そして、前記ドラム本体１４の偏心方向Ｆ１と、フランジ部材１６、１８の偏心方向Ｆ２とを、両端の嵌合穴１４０６の中心Ｃ１に対するドラム本体１４の外周面の中心Ｃ２の偏心量と、軸受部１６０４、１８０４の中心Ｃ３に対する環板部１６０２、１８０２の中心Ｃ４の偏心量とを増幅する方向にして、突き当て面１６０６、１８０６がドラム本体１４の端面１４０８に突き当たるまで、環板部１６０２、１８０２がドラム本体１４の嵌合穴１４０６に圧入され、固定されている。
言い換えると、本実施の形態では、前記ドラム本体１４の偏心方向Ｆ１と、フランジ部材１６、１８の偏心方向Ｆ２とをほぼ同じ向きにして、突き当て面１６０６、１８０６がドラム本体１４の端面１４０８に突き当たるまで、環板部１６０２、１８０２がドラム本体１４の嵌合穴１４０６に圧入され、固定されている。
より詳細に説明すると、例えば、偏心方向Ｆ１を鉛直方向で上向きとした状態のドラム本体１４に対して、偏心方向Ｆ２を±６０度の範囲で上向きとした、好ましくは、偏心方向Ｆ２を±１５度の範囲で上向きとした、より好ましくは、偏心方向Ｆ２を鉛直方向で上向きとしたフランジ部材１６、１８がそれらの環板部１６０２、１８０２をドラム本体１４の嵌合穴１４０６に圧入され、固定されている。
【００１４】
本実施の形態にかかる感光体ドラム１２によれば、ドラム本体１４の偏心量とフランジ部材１６、１８の偏心量とが増幅され、組み立てられた感光体ドラム１２の偏心方向（フランジ部材１６、１８の軸受部１６０４、１８０４の中心を結ぶ中心線に対する感光体ドラム１２の外周面の偏心方向）のばらつきを小さく抑えることができる。
したがって、ドラム本体１４やフランジ部材１６、１８の加工精度（製造精度）について実現不能な高精度を要求することなく、加工精度（製造精度）上の誤差を有するドラム本体１４とフランジ部材１６、１８から偏心方向のばらつきの少ない感光体ドラム１２が得られる。
この場合、ドラム本体１４の外周面の中心Ｃ２と軸受部１６０４、１８０４の中心Ｃ３との距離が０〜５０μであることが好ましく、０〜３０μであればより好ましい。
【００１５】
なお、上記の実施の形態では、環板部１６０２、１８０２がドラム本体１４の嵌合穴１４０６に圧入されることで、ドラム本体１４の両端にフランジ部材１６、１８が固定される場合について説明したが、嵌合穴１４０６の内周面に接着剤を塗布しておき、突き当て面１６０６、１８０６がドラム本体１４の端面１４０８に突き当たるまで、環板部１６０２、１８０２を嵌合穴１４０６に嵌め込み、これによりドラム本体１４の両端にフランジ部材１６、１８が固定される感光体ドラム１２や、接着剤を用いずに圧入する感光体ドラム１２でも、突き当て面１６０６、１８０６が、フランジ部材１６、１８を構成する各箇所の基準面となる場合があり、この場合には次のように構成されている。
図３を参照して説明すると、フランジ部材１６、１８は合成樹脂製で型成形により形成され、許容範囲内において加工誤差（製造誤差）を有しており、フランジ部材１６、１８の軸受部１６０４、１８０４の中心軸線Ｃは、突き当て面１６０６、１８０６を通る仮想平面Ｐに対して直交しておらず、フランジ部材１６、１８の軸受部１６０４、１８０４の中心を通り前記仮想平面Ｐに対して直交する垂線Ｈに対して傾斜しており、図３において符号Ｆ３は、感光体ドラム１２の長手方向端部における前記垂線Ｈに対する中心軸線Ｃの傾斜方向を示す。より詳細には、仮想平面Ｐに直交する垂線Ｈと、軸受部１６０４、１８０４の中心軸線Ｃが軸受部１６０４、１８０４の内部で交差した場合に、軸受部１６０４、１８０４から見て感光体ドラム１２の外部側で、当該軸線Ｃが垂線Ｈに対してずれる方向がフランジ部材１６、１８の中心軸線の傾斜方向である。
【００１６】
この場合には、嵌合穴１４０６の内周面に接着剤を塗布しておき、前記ドラム本体１４の偏心方向Ｆ１と、フランジ部材１６、１８の中心軸線Ｃの傾斜方向Ｆ３とをほぼ逆向きにして、突き当て面１６０６、１８０６がドラム本体１４の端面１４０８に突き当たるまで、環板部１６０２、１８０２がドラム本体１４の嵌合穴１４０６に嵌め込まれ、固定されている。
より詳細に説明すると、例えば、偏心方向Ｆ１を鉛直方向で上向きとした状態のドラム本体１４に対して、傾斜方向Ｆ３を±６０度の範囲で下向きとした、好ましくは、傾斜方向Ｆ３を±１５度の範囲で下向きとした、より好ましくは、傾斜方向Ｆ３を鉛直方向で下向きとしたフランジ部材１６、１８が、それらの環板部１６０２、１８０２がドラム本体１４の嵌合穴１４０６に嵌め込まれ、突き当て面１６０６、１８０６がドラム本体１４の端面１４０８に当接した状態で固定されている。
【００１７】
このような感光体ドラム１２によっても、前記と同様に、ドラム本体１４の偏心量とフランジ部材１６、１８の偏心量とが増幅され、組み立てられた感光体ドラム１２の偏心方向のばらつきを小さく抑えることができ、したがって、加工精度（製造精度）上の誤差を有するドラム本体１４とフランジ部材１６、１８から偏心方向のばらつきの少ない感光体ドラム１２が得られる。
【００１８】
つぎに、図４を参照して上記の感光体ドラム１２を組み立てる方法について説明する。
図４（Ａ）は感光体ドラムを組み立てる組み立て装置の正面図、（Ｂ）はＶブロックでドラム本体を支持した状態の側面図を示す。
組み立て装置２０は、ドラム本体１４の両端を回転可能に支持できるようにした一対の支持部２２と、夫々の支持部２２の近傍に１つずつ配設された一対の載置部２４と、一対の支持部２２によって支持されたドラム本体１４の外周面までの距離を検出するように配設された距離センサ２６と、距離センサ２６が出力するセンサ信号を処理すると共に、この組み立て装置２０の様々な部分の制御を行う制御部２８とを備えている。
制御部２８は、距離センサ２６から供給されるセンサ信号をコンピュータが読込可能なディジタル信号に変換する信号変換回路と、変換されたディジタル信号を読込んで処理すると共に、予めインストールされた制御プログラムに従って必要な制御を実行するコンピュータとを含んでいる。
【００１９】
前記支持部２２は、例えば、互いに対向するように基台から立設された一対の支持壁２２０２と、これら支持壁２２０２が向かい合う面に配設されそれぞれ支持壁２２０２で回転可能に支持された一対の軸状部材２２０４とで構成されている。
前記軸状部材２２０４は、ドラム本体の嵌合穴１４０６に挿入され係合されるように、先端に至るにつれてその直径が次第に小さくなるような円錐状に形成され、軸状部材２２０４は、例えば、合成樹脂や金属により形成されている。
前記一対の支持壁２２０２は、互いに離間接近する方向に移動可能に配設され、これら一対の支持壁２２０２の直線運動は、例えば、エアシリンダーなどの駆動手段により行われ、この駆動手段の制御は前記制御部２８で行われる。
また、一対の支持壁２２０２のうちの一方の支持壁２２０２にはモータ３０が配設され、モータ３０により一方の軸状部材２２０４が回転されるように構成され、前記モータ３０の回転制御は制御部２８で行われる。
【００２０】
前記載置部２４は、一対の軸状部材２２０４で支持されたドラム本体１４の長手方向両端寄りの下方にそれぞれ位置するように配設されたＶブロック２４０２と、各Ｖブロック２４０２を昇降させる昇降手段２４０４とで構成されている。
前記Ｖブロック２４０２は、上方が開放されてドラム本体１４の外周面が挿入され係合されるＶ溝２４０６を有し、Ｖブロック２４０２は、例えば、弾性を有するゴムなどにより形成され、昇降手段２４０４は、たとえば、エアーシリンダにより構成され、前記昇降手段２４０４の制御は制御部２８で行われる。
前記距離センサ２６は、一対の軸状部材２２０４で支持されたドラム本体１４の長手方向中央の上方に臨むように配設され、距離センサ２６としては、例えば、レーザ干渉計を利用した高精度の距離センサを用いることができる。
距離センサ２６からは測定値を表すセンサ信号が出力され、このセンサ信号は制御部２８へ供給される。
制御部２８は、距離センサ２６のセンサ信号から得られた測定値に対して所定の演算処理を施すことで、ドラム本体１４の仮想中心軸（ドラム本体１４の両端の嵌合穴１４０６の中心を結んだ軸線）に対する外周面の偏心量とその偏心方向とを算出する。
【００２１】
つぎに、上記の組み立て装置２０を用いて感光体ドラム１２を組み立てる手順について説明する。
まず、一対の支持部２２を、それらの軸状部材２２０４の先端間の距離がドラム本体１４の長手方向の寸法よりも大きくなるように離しておく。
つぎに、Ｖ溝２４０６で支持されたドラム本体１４の中心と、軸状部材２２０４の中心とがほぼ同じ高さになるように、一対のＶブロック２４０２を上昇させ、各Ｖブロック２４０２のＶ溝２４０６にドラム本体１４の長手方向両端寄り部分を載せる。
つぎに、一対の支持部２２を互いに近づける方向に移動させ、一対の軸状部材２２０４を、ドラム本体１４の両端の嵌合穴１４０６に挿入して係合させ、ドラム本体１４を一対の軸状部材２２０４で支持する。
つぎに、Ｖブロック２４０２を下降させ、ドラム本体１４からＶブロック２４０２を離す。
【００２２】
つぎに、距離センサ２６によって、この距離センサ２６からドラム本体１４の外周面上の測定点までの距離を測定する。図示例では、ドラム本体１４の外周面の長手方向中央で、そのとき真上を向いている部分が測定点となる。そして、モータ３０を制御してドラム本体１４を回転させ、ドラム本体１４の角度位置を所定の角度間隔で変更しながら、次々と測定を行うことで、ドラム本体１４の周囲の一周分の測定データを収集する。
こうしてデータの収集が完了したならば、制御部２８では、そのデータが、そのドラム本体１４の仮想中心軸（ドラム本体１４の両端の嵌合穴１４０６の中心を結んだ軸線）に対して未知の偏心量だけ偏心した円を表している、ただし測定誤差を含んだデータであると見なして、曲線当てはめ法を適用することで、その円の中心位置を求める。そして、ドラム本体１４の仮想中心軸に対するその円の中心位置のずれから、ドラム１４の外周面の偏心量と偏心方向Ｆ１を決定する。
こうしてドラム１４の外周面の偏心方向Ｆ１が得られたならば、続いて、制御部２８は、モータ３０を制御してドラム１４を回転させ、その偏心方向Ｆ１を所定方向（図示例では、真上の方向）へ向ける。
【００２３】
つぎに、Ｖブロック２４０２を上昇させ、ドラム本体１４の外周面を押圧することなくドラム本体１４の外周面にＶ溝２４０６を接触させ、一対の支持部２２を互いに離れる方向に移動させる。
これにより、一対の軸状部材２２０４は、ドラム本体１４の両端の嵌合穴１４０６から抜き出され、ドラム本体１４は、偏心方向Ｆ１が鉛直方向で上向きとなった状態で一対のＶブロック２４０２のＶ溝２４０６上に載置され、支持されることになる。
【００２４】
つぎに、一対のＶブロック２４０２を、水平方向で一対の支持部２２が離間接近する方向に対して直交する方向に移動させ、該箇所でドラム本体１４両側の嵌合穴１４０６にエアーシリンダなどを用いて、フランジ部材１６、１８の突き当て面１６０６、１８０６がドラム本体１４の端面１４０８に突き当たるまで、フランジ部材１６、１８を圧入する。
この場合、フランジ部材１６、１８は合成樹脂製で型成形されており、軸受部１６０４、１８０４の中心に対する環板部１６０２、１８０２の中心のずれの方向、すなわち偏心方向Ｆ２は予め判明しているので、例えば、偏心方向Ｆ２に印を付けるなどして、その偏心方向Ｆ２を鉛直方向で上向きにしてドラム本体１４の両側の嵌合穴１４０６にフランジ部材１６、１８を圧入し、これにより感光体ドラム１２が得られる。
【００２５】
なお、嵌合穴１４０６の内周面に接着剤を塗布しておき、突き当て面１６０６、１８０６がドラム本体１４の端面１４０８に突き当たるまで、環板部１６０２、１８０２を嵌合穴１４０６に嵌め込み、突き当て面１６０６、１８０６が、フランジ部材１６、１８を構成する各箇所の基準面となる感光体ドラム１２のような場合には、ドラム１４の外周面の偏心量と偏心方向Ｆ１を求めた後、偏心方向Ｆ１を鉛直方向で上向きとした状態のドラム本体１４に対して、フランジ部材１６、１８の中心軸線Ｃの傾斜方向Ｆ３を鉛直方向で下向きにして環板部１６０２、１８０２を嵌合穴１４０６に嵌め込み、突き当て面１６０６、１８０６をドラム本体１４の端面１４０８に当接させればよく、これにより感光体ドラム１２が得られる。
【００２６】
本実施の形態に係る組み立て方法によれば、ドラム本体１４の偏心量とフランジ部材１６、１８の偏心量とが増幅され、ドラム本体１４やフランジ部材１６、１８の加工精度（製造精度）について実現不能な高精度を要求することなく、偏心方向のばらつきの少ない感光体ドラム１２が得られる。
そして、本実施の形態に係る組み立て方法によれば、ドラム本体１４の偏心方向Ｆ１の計測から、両端のフランジ部材１６、１８の嵌め込み固定まで、一連の動作により連続的に行なうので、製造精度上の誤差を有するドラム本体１４とフランジ部材１６、１８から、高精度要求を満たすの感光体ドラム１２を簡単にしかも短時間で得ることが可能となる。
【００２７】
なお、ドラム本体をその軸心回りに回転させる回転方法や、ドラム本体の偏心方向を求める測定方法は、種々考えられ、実施の形態の方法に限定されない。
また、本発明は、ドラム本体の長手方向の一方の端部のみにフランジ部材を設けた片持ち式の感光体ドラムの場合にも当然適用される。
【００２８】
本発明において用いる感光体ドラム１２は、導電性支持体（筒体１４０２）上に感光層１４０４を具備してなるものである。感光層１４０４は、電荷発生層と電荷輸送層が別に構成されたいわゆる積層型のものと、一つの層からなる単層型のものがあるが、感度等の観点からは積層型の電子写真感光体が好ましい。特に高感度が要求されるフルカラー用の電子写真感光体においては、積層型の電子写真感光体が好適に用いられる。以下、積層型を例に挙げて感光体ドラム１２を説明する。
電荷発生層に含有される電荷発生剤としては、セレン及びその合金、ヒ素−セレン、硫化カドミウム、酸化亜鉛、その他の無機光導電体、フタロシアニン類、アゾ系、キナクリドン系、多環キノン系、ペリレン系、インジゴ系、スクアリリウム色素系、アズレニウム色素系、チアピリリウム系、ベンズイミダゾール系などの有機顔料を使用することができる。特に銅、塩化インジウム、塩化カリウム、スズ、オキシチタニウム、亜鉛、バナジウムなどの金属、またはその酸化物や塩化物の配位したフタロシアニン類、無金属フタロシアニン類、または、モノアゾ、ビスアゾ、トリスアゾ、ポリアゾ類などのアゾ顔料が好ましい。これらのうち特にアゾ顔料又はフタロシアニン類がより好ましく、いわゆるＹ型オキシチタニウムフタロシアニンが高感度を得ることができるため特に好ましい。なお、電荷発生剤は、単独で用いても２種以上を含んで用いても良い。例えば、いわゆるＹ型オキシチタニウムフタロシアニンと、いわゆるβ型オキシチタニウムフタロシアニンやα型オキシチタニウムフタロシアニンの混合物を電荷発生剤として用いてもよい。
【００２９】
いわゆるＹ型オキシチタニウムフタロシアニンとは、ＣｕＫα線によるＸ線回折においてブラッグ角（２θ±０．２）２７．３゜に最大回折ピークを示すものである。この結晶型オキシチタニウムフタロシアニンは、一般にはＹ型あるいはＤ型と呼ばれているものであり、例えば特開昭６２−６７０９４号公報の第２図（同公報ではＩＩ型と称されている）、特開平２−８２５６号公報の第１図、特開昭６４−８２０４５号公報の第１図、電子写真学会誌第９２巻（１９９０年発行）第３号第２５０〜２５８頁（同刊行物ではＹ型と称されている）に示されたものである。この結晶型オキシチタニウムフタロシアニンは、２７．３°に最大回折ピークを示すことが特徴であるが、これ以外に通常７．４゜、９．７゜、２４．２゜にピークを示す。
なお、回折ピークの強度は、結晶性、試料の配向性及び測定法により変化する場合もあるが、粉末結晶のＸ線回折を行う場合に通常用いられるブラッグ−ブレンダーノの集中法による測定では、上記のＹ型オキシチタニウムフタロシアニンは２７．３°に最大回折ピークを有する。また、薄膜光学系（一般に薄膜法あるいは平行法とも呼ばれる）により測定された場合には、試料の状態によっては２７．３°が最大回折ピークとならない場合があるが、これは結晶粉末が特定の方向に配向しているためと考えられる。
【００３０】
電荷発生剤の分散媒としては種々の溶媒を用いてよい。例えば、ジエチルエーテル、ジメトキシエタン、テトラヒドロフラン、１，２−ジメトキシエタン等のエーテル類；アセトン、メチルエチルケトン等のケトン類；酢酸メチル、酢酸エチル等のエステル類；メタノール、エタノール、プロパノール等のアルコール類を単独あるいは２種以上混合して使用することができる。
用いる分散媒の量は分散が充分行え、且つ分散液中に有効量の電荷発生剤が含まれる限りいかなる量でもよく、通常は分散時の分散液中の電荷発生剤の濃度にして３〜２０ｗｔ％、より好ましくは４〜２０ｗｔ％程度が好ましい。
電荷発生層に用いられる結着樹脂としてはポリビニルブチラール、ポリビニルアセタール、ポリエステル、ポリカーボネート、ポリスチレン、ポリエステルカーボネート、ポリスルホン、ポリイミド、ポリメチルメタクリレート、フノール樹脂、ブチラール樹脂、ポリ塩化ビニル等のビニル重合体、及びその共重合体、フェノキシ、エポキシ、シリコーン樹脂等またこれらの部分的架橋硬化物等を単独あるいは２種以上用いることができる。
【００３１】
結着樹脂と電荷発生剤粒子との混合方法としては例えば、電荷発生剤粒子を分散処理中に結着樹脂を粉末のまま或いはそのポリマー溶液を加え同時に分散する方法、分散液を結着樹脂のポリマー溶液中に混合する方法、或いは逆に分散液中にポリマー溶液を混合する方法等のいずれかの方法を用いてもかまわない。
次にここで得られた分散液は、塗布をするのに適した液物性にするために、種々の溶剤を用いて希釈してもかまわない。このような溶剤としては、例えば前記分散媒として例示した溶媒を使用することができる。電荷発生剤と結着樹脂との割合は特に制限はないが一般には樹脂１００重量部に対して電荷発生剤が５〜５００重量部の範囲より使用される。
【００３２】
電荷移動層に含有される電荷移動剤としては例えば、２，４，７−トリニトロフルオレノン、テトラシアノキシジメタンなどの電子求引性物質、セルバゾール、インドール、イミダゾール、オキサゾール、ピラゾール、オキサジアゾール、ピラゾリン、チアジアゾールなどの複素環化合物、アニリン誘導体、ヒドラゾン化合物、芳香族アミン誘導体、スチルベン誘導体、或いはこれらの化合物からなる基を主鎖もしくは側鎖に有する重合体などの電子供与性物質が挙げられる。電荷移動層についても電荷発生層と同様の結着樹脂等を用いることができる。特に、電荷移動層との相溶性の高い結着樹脂を用いることが好ましい。電荷移動剤と結着樹脂との割合は結着樹脂１００重量に対して電荷移動物質が５〜５００重量部の範囲により電荷移動層用の分散液が調製される。
【００３３】
このようにして調製された分散液を用いて、導電性支持体上に電荷発生層を形成させ、その上に電荷移動層を積層させて感光層１４０４を形成する。電荷発生層の膜厚は電荷移動層と積層させて感光層１４０４を形成する場合０．１μｍ〜１０μｍの範囲が好適であり、電荷移動層の膜厚は１０〜４０μｍが好適である。
本発明において用いられる電子写真感光体の導電性支持体としては、特に限定されるものではないがアルミニウムまたはアルミニウム合金が好適に使用される。
アルミニウム導電性支持体の材質としては、例えば、ＪＩＳ１０５０、ＪＩＳ１０７０、ＪＩＳ１０８０等の純アルミニウムまたは、ＡＬ−Ｍｇ系合金、ＡＬ−Ｃｕ系合金、ＡＬ−Ｓｉ系合金、ＡＬ−Ｍｇ−Ｓｉ系合金、ＡＬ−Ｃｕ−Ｓｉ系合金等の種々のアルミニウム合金が挙げられ、より好ましくはＡＬ−Ｍｎ系合金であるＪＩＳ３００３、ＡＬ−Ｓｉ系合金であるＪＩＳ６０６３等が挙げられる。なお、本発明において「アルミニウム」という時はアルミニウム合金と分けて表現しない限り、通常、アルミニウム合金も含めた総称を表す。
【００３４】
これらのアルミニウム製導電性支持体の製造法は特に限定されないが、アルミニウムビレットをポートホール法、マンドレル法等により押し出し管に加工し、続いて所定の肉厚、外径寸法の円筒とするため、引き抜き加工、インパクト加工、しごき加工、あるいは切削による鏡面加工を行うことで作ることができる。導電性支持体表面には引き抜き油、切削油、防錆油、空気中の各種塵埃等が付着しているため、通常、光導電層を形成する前に洗浄処理が行われる。
公知の方法で製造した導電性支持体は、完全な円筒形状であることは望めず、素材の偏肉や、曲がりを合わせ数μｍ〜数十μｍ程度の振れが存在する。この振れをより小さくすることにより電子写真感光体の精度を高めることも考えられる。しかしながら、コストが非常にかかり必ずしも現実的ではない。
導電性支持体と電荷発生層の間には通常使用されるような公知のバリアー層が設けられてもよい。また、感光層１４０４の外面には、表面保護層が設けられていても良い。
【００３５】
バリアー層としては、例えば陽極酸化被膜、酸化アルミニウム、水酸化アルミニウム等の無機層、ポリビニルアルコール、カゼイン、ポリビニルピロリドン、ポリアクリル酸、セルロース類、ゼラチン、デンプン、ポリウレタン、ポリイミド、ポリアミド等の有機層が使用される。バリアー層の膜厚は０．１μｍ〜２０μｍ、好ましくは０．１μｍ〜１０μｍの範囲で使用されるのが最も効果的である。
導電性支持体の上に設けられる電荷発生層、電荷移動層、保護層（以下この欄において「感光層１４０４」という）の厚さの合計としては、１０μｍ〜５０μｍ程度が好適に設定される。特に、感光層１４０４が厚い場合には、感光層１４０４自体のムラが生じやすく本発明がより好適に適用される。このような感光層１４０４の厚さとしては、２０〜５０μｍが好ましく、２５〜５０μｍであればより好ましく、３０〜５０μｍであれば特に好ましい。
【００３６】
本発明の感光体ドラム１２を用いた画像形成装置としては、プリンター、複写機、ファクシミリ等があげられる。
本発明の電子写真感光体は、振れが少なく構成されているので、特にフルカラー用のプリンター、複写機、ファクシミリ等に好適に用いることができる。
画像形成装置には、記憶装置▲１▼、記憶装置▲２▼、記憶装置▲３▼、記憶装置▲４▼、ホッパー、スタッカー、記録媒体（用紙）を搬送する搬送路、定着ユニットが設けてある。記憶装置▲１▼〜▲４▼には、それぞれ現像ユニット（帯電器、現像器、定着器、除電器、クリーナ）、電子写真感光体、光学ユニット（露光器）が設けてある。
記録装置▲１▼は、イエロー（以下「Ｙ」という。）の現像ユニットと、電子写真感光体と、光学ユニットを具備する。記録装置▲２▼は、マゼンダ（以下「Ｍ」という。）の現像ユニットと電子写真感光体と、光学ユニットを具備する。記録装置▲３▼は、シアン（以下「Ｃ」という。）の現像ユニットと電子写真感光体と、光学ユニットを具備する。記録装置▲４▼は、ブラック（以下「Ｋ」という）の現像ユニットと、電子写真感光体と、光学ユニットを具備する。
【００３７】
ホッパーは、用紙を搬送路に提供するものである。スタッカーは、印刷済みの用紙を積み重ねて保存するものである。搬送路は、用紙を搬送するものである。定着ユニットは、電子写真感光体から用紙に転写された画像を定着するものである。
現像ユニットは、電子写真感光体に形成された潜像に現像材（Ｙ、Ｍ、Ｃ、Ｋの各記録装置に対応したトナー）を与えて現像を行うものである。電子写真感光体は、得ようとする画像に応じた静電潜像を作成後、現像ユニットで現像された画像を用紙に転写するものである。光学ユニットは、各画像データ（情報）により変調されたレーザ光で電子写真感光体上を走査して静電潜像を形成するものである。
【００３８】
画像形成装置の動作を以下説明する。
コロトロン、ストロコロン等の帯電器を用いて電子写真感光体表面略均一に帯電する。上位コンピュータは、画像、文字等の情報に基づき印刷指令を送る。上位コンピュータからの印刷指令時に、印刷準備が整っていなければ、装置ビズィーを応答し、印刷準備が整っていれば、データ要求を行う。上位コンピュータから、Ｙデータ、Ｍデータ、Ｃデータ、Ｋデータが送られてくると、画像形成装置の記録装置▲１▼〜▲４▼は、光学ユニットで各色データに対応して変調されたレーザ光で各電子写真感光体上を走査する。これにより、レーザ光が照射された電子写真感光体上の部分は、電荷が除去され、電子写真感光体上に静電潜像が形成される。
【００３９】
その後、各現像ユニットで該電子写真感光体に形成された静電潜像にトナー等の現像材を与えて、電子写真感光体上に可視像を形成する。次に、用紙をこの可視像に重ね、用紙の裏から帯電器で現像材とは逆の電荷を用紙に与え、静電力により可視像を用紙に転写する。転写された可視像は、熱又は圧力を加え、用紙に融着させて永久像とする。かかる作業を一つの用紙に対してＹ、Ｍ、Ｃ、Ｋの各色毎に行い、用紙上にカラー画像を得る。一方、転写後の電子写真感光体上の潜像電荷は、光により除電される。また、転写されずに残った残留トナー等の現像材は、クリーナにより除去する。上記、プロセスを繰り返すことにより、連続的に画像形成を行う。
【００４０】
また、用紙がホッパーで一枚ずつ搬送路におくられ、ベルト状の搬送手段で用紙が搬送される間に電子写真感光体に掲載された各色の現像済みの像を順次用紙に転写していき、定着ユニットで用紙に転写された像を定着し、最後に、スタッカーで印刷済みの用紙を積み重ねて手保管する。
なお、画像形成装置としては、各電子写真感光体上に付着した現像材（各色トナー）を、一端一つの中間転写ベルトに転写し、中間転写ベルト上で各色のトナーを合わせ、カラー可視像とした後、転写手段を用いて用紙に画像を形成するものであっても良い。
【００４１】
【発明の効果】
以上の説明で明らかなように、本発明の感光体ドラムによれば、製造精度上の誤差を有するドラム本体とフランジ部材から偏心方向のばらつきの少ない感光体ドラムが得られる。
また、本発明の感光体ドラムの組み立て方法によれば、製造精度上の誤差を有するドラム本体とフランジ部材から、高精度要求を満たすの感光体ドラムを簡単にしかも短時間で得られる。
また、本発明の画像形成装置によれば、位置ずれや色ずれなどのような歪みやぼけのない明瞭な画像が得られる。
【図面の簡単な説明】
【図１】感光体ドラムの説明図である。
【図２】（Ａ）はドラム本体の加工誤差の説明図、（Ｂ）はフランジ部材の加工誤差の説明図である。
【図３】フランジ部材の突き当て面が基準面となる場合の説明図である。
【図４】（Ａ）は感光体ドラムを組み立てる組み立て装置の正面図、（Ｂ）はＶブロックでドラム本体を支持した状態の側面図である。
【符号の説明】
１２感光体ドラム
１４ドラム本体
１４０２筒体
１４０６嵌合穴
１６、１８フランジ部材
１６０２、１８０２環板部
１６０４、１８０４軸受部
１６０６、１８０６突き当て面[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photosensitive drum used in an electrophotographic apparatus such as a copying machine or a printer, an assembling method thereof, and an image forming apparatus using the photosensitive drum.
[0002]
[Prior art]
In recent years, the demand for higher accuracy of the photosensitive drum has been increased due to the promotion of high resolution, color, and miniaturization of the electrophotographic apparatus.
That is, if the photosensitive drum is bent (the photosensitive drum itself is curved) or has an axial deviation (the center of the outer peripheral surface of the photosensitive drum is shifted from the rotation center), the bending or axial deviation is caused. Due to this swinging, an image shift from a position where it should originally be formed occurs during electrostatic latent image formation and transfer.
More specifically, in the case of performing laser scanning using a polygon mirror such as a laser beam printer, when forming an electrostatic latent image, the laser beam is incident obliquely toward the end of the photosensitive drum. If the photosensitive drum is bent or misaligned, a main scanning direction misalignment occurs in which the laser beam arrival position deviates in the drum axis direction. If the photosensitive drum is bent or misaligned, the distance from the rotation center of the photosensitive drum to the surface of the photosensitive drum, that is, the difference in the rotation radius, the exposure of the surface of the photosensitive drum at a portion with a small rotation radius. The moving speed with respect to the system becomes slow and the electrostatic latent image is clogged, and at a portion having a large rotation radius, the moving speed with respect to the exposure system on the surface of the photosensitive drum becomes faster and the sub-scanning direction shift in which the electrostatic latent image extends is generated.
[0003]
As a result, the printed image is distorted. In particular, in the case of a color copying machine called a tandem type that uses a plurality of photosensitive drums arranged in parallel, the positional deviation and the color deviation become prominent.
In addition, when a light emitting diode is used as an exposure apparatus, the focal length is short, so that the image blur due to shaking is likely to occur, and there is a serious problem.
For these reasons, it is necessary to improve the accuracy of the photosensitive drum, particularly to improve the rotational accuracy.
[0004]
[Problems to be solved by the invention]
On the other hand, as shown in FIG. 1, the photosensitive drum 12 includes a drum body 14 in which a photosensitive layer 1404 is formed on the surface of a cylindrical body 1402, and flange members disposed in fitting holes 1406 at both ends of the drum body 14. 16 and 18.
The flange members 16 and 18 are located at the base ends of the ring plate portions 1602 and 1802 that are fitted and fixed in the fitting holes 1406, the bearing portions 1604 and 1804 supported on the frame side, and the ring plate portions 1602 and 1802. The annular plate portions 1602 and 1802 are provided with annular abutting surfaces 1606 and 1806 that abut against the end surface 1408 of the drum main body 14 (tubular body 1402) when the annular plate portions 1602 and 1802 are fitted into the fitting holes 1406. Is provided with a gear portion 1608 for rotating the drum body 12.
The flange members 16 and 18 are attached to the drum body 14 by fitting the ring plate portions 1602 and 1802 of the flange members 16 and 18 into the fitting holes 1406 at both ends of the drum body 14 and fixing them.
More specifically, until the abutting surfaces 1606 and 1806 of the flange members 16 and 18 abut against the end surface 1408 of the drum body 14, the ring plate portions 1602 and 1802 of the flange members 16 and 18 are fitted into the fitting holes at both ends of the drum body 14. It is fixed by press-fitting into 1406.
Alternatively, an adhesive is applied to the inner peripheral surfaces of the fitting holes 1406 at both ends of the drum main body 14, and the ring plate until the abutting surfaces 1606 and 1806 of the flange members 16 and 18 abut against the end surfaces 1408 of the drum main body 14. The parts 1602 and 1802 are fixed by being fitted into the fitting holes 1406.
Further, the arrangement of the photosensitive drum 12 on the frame side is performed by rotatably supporting the bearing portions 1604 and 1804 of the flange members 16 and 18 on the frame side. In addition, when the bearing parts 1604 and 1804 of the flange members 16 and 18 are hole-shaped, it is supported rotatably through the shaft on the frame side, and when the bearing parts 1604 and 1804 are shaft-shaped, the bearings of the frame are supported. It will be rotatably supported through the hole.
[0005]
As described above, the photosensitive drum 12 includes the single drum main body 14 and the two flange members 16 and 18, and the drum main body 14 and the flange members 16 and 18 are respectively processed according to the design dimensions. This is difficult in terms of processing accuracy, and actually has a processing error (manufacturing error) within an allowable range.
That is, with respect to the drum main body 14, the cylindrical body 1402 constituting the drum main body 14 is often made of an aluminum alloy, and a swing of several tens of microns already exists due to uneven thickness and bending of the material. In addition, since there is a subtle internal stress difference in each part of the cylindrical body 1402, there is a limit to the normal processing accuracy with improved productivity.
In addition, the thickness of the photosensitive layer 1404 provided on the surface of the cylindrical body 1402 is not uniform in the circumferential direction of the cylindrical body 1402, and strictly varies.
In addition, the fitting holes 1406 at both ends of the cylindrical body 1402 are not necessarily coincident with the center of the fitting hole 1406 and the outer peripheral surface of the drum main body 14 with high accuracy, and the flange members 16 and 18 are formed in the fitting hole 1406. Since the drum body 14 is fixed and the drum body 14 rotates via the flange members 16 and 18, the center of the fitting hole 1406 and the center of the outer peripheral surface of the drum body 14 are displaced, which causes a swing.
[0006]
As for the flange members 16 and 18, in many cases, the flange members 16 and 18 are made of synthetic resin and have a processing error (manufacturing error) within an allowable range.
In other words, the center of the ring plate portions 1602 and 1802 and the center of the bearing portions 1604 and 1804 are off, and if the structure in which the ring plate portions 1602 and 1802 are press-fitted and fixed in the fitting holes 1406 is used, it causes a swing. .
The central axes of the bearing portions 1604 and 1804 are not orthogonal to the virtual plane passing through the abutting surfaces 1606 and 1806, and are inclined, and an adhesive is applied to the inner peripheral surface of the fitting hole 1406. In addition, in the structure in which the ring plate portions 1602 and 1802 are fitted into the fitting holes 1406 until the abutting surfaces 1606 and 1806 abut against the end surface 1408 of the drum body 14, the abutting surfaces 1606 and 1806 are the reference surfaces. As a result, it also causes a swing.
[0007]
Although it is speculated that the drum main body 14 and the flange members 16 and 18 can be further improved in accuracy, the productivity is remarkably hindered, so the feasibility is poor.
That is, it is difficult to obtain the photosensitive drum 12 that satisfies the demand for higher accuracy by further increasing the accuracy of the members constituting the photosensitive drum 12 in terms of the unit price and manufacturing cost of the photosensitive drum 12. Become.
These problems are the same in the case of a cantilever type photosensitive drum provided with a flange member only at one end in the longitudinal direction of the drum body.
The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a photosensitive drum that can satisfy high accuracy requirements without requiring high accuracy with poor feasibility for a drum body or a flange member. Is to provide.
It is another object of the present invention to provide a method for assembling a photosensitive drum, which can obtain the above photosensitive drum easily and quickly.
Another object of the present invention is to provide an image forming apparatus using the above-described photosensitive drum. In view of such a situation, the present inventor invented a technique for assembling a photosensitive drum with high accuracy in Japanese Patent Application No. 2000-155971. In particular, in designing a tandem machine, each drum has a different accuracy from that of a single product. It is common practice to manage the eccentric direction. In the above invention, since the eccentric amount of the drum and the flange member is fitted in the direction to cancel each other, even if a slight misalignment occurs, the eccentric direction after assembly is greatly displaced, and there is a disadvantage that the eccentric direction is likely to vary. There was a case that became a problem in managing the direction.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the photosensitive drum of the present invention is configured such that the eccentric direction of the drum body and the eccentric direction of the flange member are set to a direction that amplifies the mutual eccentric amount, and the annular plate portion of the flange member is fitted to the drum body. It is characterized by being fitted into a hole and fixed.
In the photosensitive drum of the present invention, the annular plate portion of the flange member is fitted into the fitting hole of the drum body with the direction of eccentricity of the drum body and the direction of inclination of the central axis of the flange member substantially reversed. The abutting surface is abutted against and fixed to the end surface of the drum body.
In the method for assembling the photosensitive drum of the present invention, the eccentric direction of the flange member is obtained in advance, and the eccentric direction of the drum body is obtained on a rotating device capable of rotating the drum body about its axis. After obtaining the eccentric direction of the drum body, the drum body is rotated on the rotating device, the eccentric direction of the drum body is made to coincide with the predetermined direction, and the eccentric direction of each flange member is substantially the same with respect to the predetermined direction. The ring plate portion of each flange member is fitted and fixed in the fitting hole of the drum body in the direction.
In the method for assembling the photosensitive drum of the present invention, the inclination direction of the central axis of the bearing portion of the flange member is obtained in advance, and the drum body is rotated on the rotating device capable of rotating the drum body about its axis. After determining the eccentric direction of the main body and determining the eccentric direction of the drum main body, the drum main body is rotated on the rotating device, the eccentric direction of the drum main body is made to coincide with a predetermined direction, and each flange is set to the predetermined direction. The direction of the inclination of the central axis of the bearing portion of the member is almost reversed, the ring plate portion of each flange member is fitted into the fitting hole of the drum body, and the abutting surface is abutted against the end surface of the drum body and fixed. It is characterized by that.
The image forming apparatus of the present invention is characterized by using the photosensitive drum.
[0009]
According to the photosensitive drum of the present invention, the eccentric amount of the drum body and the eccentric amount of the flange member are amplified, so that the eccentric direction after the assembly of the photosensitive drum is stabilized and the variation is reduced. Easy to manage. A photosensitive drum satisfying high accuracy requirements can be obtained from the drum body and the flange member having an error in manufacturing accuracy.
In addition, according to the method for assembling the photosensitive drum of the present invention, since it is continuously performed by a series of operations from measurement of the eccentric direction of the drum body to fitting and fixing of the flange members at both ends, there is an error in manufacturing accuracy. From the drum main body and the flange member, it is possible to easily and quickly obtain a photosensitive drum that satisfies high accuracy requirements.
Further, according to the image forming apparatus of the present invention, a clear image free from distortion and blur such as misregistration and color misregistration can be obtained.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the photosensitive drum according to the embodiment of the present invention will be described together with its assembling method.
Referring to FIG. 1, the individual members constituting the photosensitive drum 12 are the same as those described in the prior art.
That is, the photosensitive drum 12 includes a drum body 14 and two flange members 16 and 18. The drum body 14 includes a cylindrical body 1402 in which fitting holes 1406 are formed at both ends in the longitudinal direction, and a photosensitive layer 1404 formed on the outer peripheral surface of the cylindrical body 1402. The flange members 16 and 18 are fixed by fitting their ring plate portions 1602 and 1802 into the fitting holes 1406 at both ends of the drum main body 14.
[0011]
In many cases, the cylindrical body 1402 is made of an aluminum alloy, and there is already a swing of several tens of microns due to uneven thickness and bending of the material, and there is a subtle internal stress difference in each part of the cylindrical body 1402. Existing.
In addition, the thickness of the photosensitive layer 1404 also varies strictly in the circumferential direction of the cylindrical body 1402.
That is, the drum body 14 has a processing error (manufacturing error) within an allowable range. As shown in FIG. 2A, the drum body 14 has an outer peripheral surface of the drum body 14 with respect to the center C1 of the fitting holes 1406 at both ends. The center C2 is eccentric. In this case, the direction from the center C1 of the fitting hole 1406 to the center C2 of the outer peripheral surface is referred to as an eccentric direction F1 of the drum body 14.
[0012]
The flange members 16 and 18 have ring plate portions 1602 and 1802 fitted and fixed in the fitting holes 1406, bearing portions 1604 and 1804 supported on the frame side, and ring plate portions 1602 and 1802 in the fitting holes 1406. Ring-shaped abutting surfaces 1606 and 1806 that abut against the end surface 1408 of the drum main body 14 when fitted into the flange body 16, and the flange members 16 and 18 are made of synthetic resin and formed by molding.
That is, the flange members 16 and 18 have a processing error (manufacturing error) within an allowable range. As shown in FIG. 2B, the flange members 16 and 18 have the ring plate portions 1602 and 1802 with respect to the center C3 of the bearing portions 1604 and 1804. The center C4 is eccentric. In this case, the direction from the center C3 of the bearing portions 1604 and 1804 to the center C4 of the ring plate portions 1602 and 1802 is referred to as an eccentric direction F2 of the flange members 16 and 18.
[0013]
The eccentric direction F1 of the drum body 14 and the eccentric direction F2 of the flange members 16 and 18 are determined by the amount of eccentricity of the center C2 of the outer peripheral surface of the drum body 14 with respect to the center C1 of the fitting holes 1406 at both ends, and the bearing portion. The ring plate portions 1602 and 1802 are made to amplify the eccentric amount of the center C4 of the ring plate portions 1602 and 1802 with respect to the center C3 of 1604 and 1804 until the abutting surfaces 1606 and 1806 hit the end surface 1408 of the drum body 14. Is press-fitted into the fitting hole 1406 of the drum body 14 and fixed.
In other words, in the present embodiment, the abutting surfaces 1606 and 1806 are arranged on the end surface 1408 of the drum body 14 with the eccentric direction F1 of the drum body 14 and the eccentric direction F2 of the flange members 16 and 18 being substantially the same direction. The ring plate portions 1602 and 1802 are press-fitted into the fitting holes 1406 of the drum body 14 and fixed until they abut.
More specifically, for example, with respect to the drum main body 14 in a state where the eccentric direction F1 is upward in the vertical direction, the eccentric direction F2 is upward in a range of ± 60 degrees, and preferably the eccentric direction F2 is ± 15. The flange members 16 and 18 with the eccentric direction F2 facing upward in the vertical direction are pressed into the fitting holes 1406 of the drum body 14 and fixed. Has been.
[0014]
According to the photosensitive drum 12 of the present embodiment, the eccentric amount of the drum body 14 and the eccentric amount of the flange members 16 and 18 are amplified, and the eccentric direction of the assembled photosensitive drum 12 (flange members 16 and 18). Variation in the eccentric direction of the outer peripheral surface of the photosensitive drum 12 with respect to the center line connecting the centers of the bearing portions 1604 and 1804 can be reduced.
Therefore, the drum main body 14 and the flange members 16 and 18 having an error in processing accuracy (manufacturing accuracy) are not required without requiring high accuracy that cannot be realized with respect to the processing accuracy (manufacturing accuracy) of the drum main body 14 and the flange members 16 and 18. Thus, the photosensitive drum 12 with little variation in the eccentric direction can be obtained.
In this case, the distance between the center C2 of the outer peripheral surface of the drum body 14 and the center C3 of the bearing portions 1604 and 1804 is preferably 0 to 50 μ, and more preferably 0 to 30 μ.
[0015]
In the above embodiment, the case where the flange members 16 and 18 are fixed to both ends of the drum main body 14 by pressing the annular plate portions 1602 and 1802 into the fitting holes 1406 of the drum main body 14 has been described. However, an adhesive is applied to the inner peripheral surface of the fitting hole 1406, and the annular plate portions 1602 and 1802 are fitted into the fitting holes 1406 until the abutting surfaces 1606 and 1806 abut against the end surface 1408 of the drum body 14, As a result, the abutting surfaces 1606 and 1806 are also provided on the flange members 16 and 18 in the photoreceptor drum 12 in which the flange members 16 and 18 are fixed to both ends of the drum body 14 and the photoreceptor drum 12 that is press-fitted without using an adhesive. In this case, the reference plane is configured as follows.
Referring to FIG. 3, the flange members 16 and 18 are made of synthetic resin and formed by molding, and have a processing error (manufacturing error) within an allowable range, and the bearing portions 1604 of the flange members 16 and 18. , 1804 is not orthogonal to the virtual plane P passing through the abutment surfaces 1606, 1806, and passes through the centers of the bearing portions 1604, 1804 of the flange members 16, 18 with respect to the virtual plane P. In FIG. 3, reference numeral F <b> 3 indicates an inclination direction of the central axis C with respect to the perpendicular H at the longitudinal end portion of the photosensitive drum 12. More specifically, when the perpendicular H perpendicular to the imaginary plane P and the central axis C of the bearing portions 1604 and 1804 intersect inside the bearing portions 1604 and 1804, the photosensitive drum 12 is viewed from the bearing portions 1604 and 1804. The direction in which the axis C deviates from the perpendicular H on the outer side is the inclination direction of the central axis of the flange members 16 and 18.
[0016]
In this case, an adhesive is applied to the inner peripheral surface of the fitting hole 1406, and the eccentric direction F1 of the drum body 14 and the inclination direction F3 of the central axis C of the flange members 16 and 18 are almost opposite to each other. Thus, the ring plate portions 1602 and 1802 are fitted into the fitting holes 1406 of the drum main body 14 and fixed until the abutting surfaces 1606 and 1806 abut against the end surface 1408 of the drum main body 14.
More specifically, for example, with respect to the drum main body 14 in a state where the eccentric direction F1 is upward in the vertical direction, the inclination direction F3 is downward in a range of ± 60 degrees, and preferably the inclination direction F3 is ± 15. The flange members 16 and 18 having a downward direction in the range of degrees, and more preferably the inclination direction F3 downward in the vertical direction, are fitted in the fitting holes 1406 of the ring plate portions 1602 and 1802 of the drum body 14, The abutting surfaces 1606 and 1806 are fixed in a state where they abut against the end surface 1408 of the drum body 14.
[0017]
Similarly to the above, the photosensitive drum 12 amplifies the eccentric amount of the drum main body 14 and the eccentric amounts of the flange members 16 and 18, and suppresses variations in the eccentric direction of the assembled photosensitive drum 12. Therefore, the photosensitive drum 12 with less variation in the eccentric direction can be obtained from the drum body 14 and the flange members 16 and 18 having errors in processing accuracy (manufacturing accuracy).
[0018]
Next, a method for assembling the photosensitive drum 12 will be described with reference to FIG.
4A is a front view of an assembling apparatus for assembling the photosensitive drum, and FIG. 4B is a side view showing a state in which the drum body is supported by the V block.
The assembling apparatus 20 includes a pair of support portions 22 that can rotatably support both ends of the drum main body 14, a pair of placement portions 24 disposed one by one near each of the support portions 22, The distance sensor 26 disposed so as to detect the distance to the outer peripheral surface of the drum body 14 supported by the support portion 22, the sensor signal output from the distance sensor 26, and various types of the assembly apparatus 20 And a control unit 28 for controlling various parts.
The control unit 28 reads a signal conversion circuit that converts a sensor signal supplied from the distance sensor 26 into a digital signal that can be read by a computer, processes the converted digital signal, and requires a control program installed in advance. And a computer that executes various controls.
[0019]
The support portion 22 includes, for example, a pair of support walls 2202 erected from a base so as to face each other, and a pair of support walls 2202 that are disposed on surfaces facing each other and are rotatably supported by the support walls 2202. And the shaft-shaped member 2204.
The shaft-shaped member 2204 is formed in a conical shape such that its diameter gradually decreases toward the tip so that the shaft-shaped member 2204 is inserted into the fitting hole 1406 of the drum body, and the shaft-shaped member 2204 is, for example, It is made of synthetic resin or metal.
The pair of support walls 2202 are disposed so as to be movable toward and away from each other, and the linear motion of the pair of support walls 2202 is performed by a driving means such as an air cylinder, for example. This is performed by the control unit 28.
In addition, the motor 30 is disposed on one support wall 2202 of the pair of support walls 2202, and one shaft-like member 2204 is rotated by the motor 30, and the rotation control of the motor 30 is controlled. This is performed by the unit 28.
[0020]
The placement unit 24 includes a V block 2402 disposed so as to be positioned below both ends in the longitudinal direction of the drum main body 14 supported by the pair of shaft-like members 2204, and a lift for moving the V blocks 2402 up and down. And means 2404.
The V block 2402 has a V groove 2406 that is open at the top and into which the outer peripheral surface of the drum body 14 is inserted and engaged. The V block 2402 is formed of, for example, elastic rubber or the like. Is constituted by, for example, an air cylinder, and the control of the elevating means 2404 is performed by the control unit 28.
The distance sensor 26 is disposed so as to face the upper center in the longitudinal direction of the drum main body 14 supported by a pair of shaft-like members 2204. As the distance sensor 26, for example, a high-precision using a laser interferometer is used. A distance sensor can be used.
A sensor signal representing a measured value is output from the distance sensor 26, and this sensor signal is supplied to the control unit 28.
The control unit 28 performs predetermined arithmetic processing on the measurement value obtained from the sensor signal of the distance sensor 26, so that the virtual central axis of the drum body 14 (the centers of the fitting holes 1406 at both ends of the drum body 14 are centered). The amount of eccentricity of the outer peripheral surface with respect to the connected axis) and the direction of eccentricity are calculated.
[0021]
Next, a procedure for assembling the photosensitive drum 12 using the assembly apparatus 20 will be described.
First, the pair of support portions 22 are separated so that the distance between the tips of the shaft-like members 2204 is larger than the longitudinal dimension of the drum body 14.
Next, the pair of V blocks 2402 are raised so that the center of the drum main body 14 supported by the V grooves 2406 and the center of the shaft-like member 2204 are almost the same height, and the V grooves of each V block 2402 are raised. A portion closer to both ends in the longitudinal direction of the drum body 14 is placed on 2406.
Next, the pair of support portions 22 are moved in a direction to approach each other, the pair of shaft-like members 2204 are inserted into the fitting holes 1406 at both ends of the drum body 14 and engaged, and the drum body 14 is paired with the shaft-like shape. A member 2204 is supported.
Next, the V block 2402 is lowered and the V block 2402 is separated from the drum body 14.
[0022]
Next, the distance sensor 26 measures the distance from the distance sensor 26 to the measurement point on the outer peripheral surface of the drum main body 14. In the example shown in the figure, the center point in the longitudinal direction of the outer peripheral surface of the drum main body 14 and the portion facing right above is the measurement point. Then, the measurement data for one round around the drum body 14 is obtained by controlling the motor 30 to rotate the drum body 14 and measuring one after another while changing the angular position of the drum body 14 at a predetermined angular interval. To collect.
When the data collection is thus completed, the control unit 28 does not know the data with respect to the virtual central axis of the drum main body 14 (the axis connecting the centers of the fitting holes 1406 at both ends of the drum main body 14). A circle decentered by the amount of eccentricity is represented, but it is regarded as data including measurement errors, and the center position of the circle is obtained by applying a curve fitting method. Then, the eccentric amount and the eccentric direction F1 of the outer peripheral surface of the drum 14 are determined from the deviation of the center position of the circle with respect to the virtual central axis of the drum body 14.
When the eccentric direction F1 of the outer peripheral surface of the drum 14 is obtained in this way, the control unit 28 then controls the motor 30 to rotate the drum 14 and sets the eccentric direction F1 to a predetermined direction (true in the illustrated example). Turn upward).
[0023]
Next, the V block 2402 is raised, the V groove 2406 is brought into contact with the outer peripheral surface of the drum main body 14 without pressing the outer peripheral surface of the drum main body 14, and the pair of support portions 22 are moved away from each other.
As a result, the pair of shaft-like members 2204 are extracted from the fitting holes 1406 at both ends of the drum body 14, and the drum body 14 has the pair of V blocks 2402 in a state where the eccentric direction F1 is upward in the vertical direction. It is placed on the V-groove 2406 and supported.
[0024]
Next, the pair of V blocks 2402 is moved in a direction perpendicular to the direction in which the pair of support portions 22 are separated and approached in the horizontal direction, and an air cylinder or the like is inserted into the fitting holes 1406 on both sides of the drum main body 14 at that location. The flange members 16 and 18 are press-fitted until the abutting surfaces 1606 and 1806 of the flange members 16 and 18 abut against the end surface 1408 of the drum body 14.
In this case, the flange members 16 and 18 are made of synthetic resin and molded, and the direction of deviation of the centers of the ring plate portions 1602 and 1802 with respect to the centers of the bearing portions 1604 and 1804, that is, the eccentric direction F2 is known in advance. Therefore, for example, by marking the eccentric direction F2, the flange members 16 and 18 are press-fitted into the fitting holes 1406 on both sides of the drum body 14 with the eccentric direction F2 facing upward in the vertical direction. A drum 12 is obtained.
[0025]
Note that an adhesive is applied to the inner peripheral surface of the fitting hole 1406, and the annular plate portions 1602 and 1802 are fitted into the fitting holes 1406 until the abutting surfaces 1606 and 1806 abut against the end surface 1408 of the drum body 14, In the case where the abutting surfaces 1606 and 1806 are the photosensitive drums 12 serving as the reference surfaces of the respective portions constituting the flange members 16 and 18, after obtaining the eccentric amount and the eccentric direction F1 of the outer peripheral surface of the drum 14. With respect to the drum main body 14 in the state where the eccentric direction F1 is upward in the vertical direction, the annular plate portions 1602 and 1802 are fitted into the fitting holes with the inclination direction F3 of the central axis C of the flange members 16 and 18 downward in the vertical direction. The photosensitive drum 12 can be obtained by fitting it into 1406 and bringing the abutting surfaces 1606 and 1806 into contact with the end surface 1408 of the drum main body 14.
[0026]
According to the assembling method according to the present embodiment, the eccentric amount of the drum main body 14 and the eccentric amounts of the flange members 16 and 18 are amplified, and the processing accuracy (manufacturing accuracy) of the drum main body 14 and the flange members 16 and 18 is realized. The photosensitive drum 12 with little variation in the eccentric direction can be obtained without requiring high precision that is impossible.
Then, according to the assembling method according to the present embodiment, from the measurement of the eccentric direction F1 of the drum main body 14 to the fitting and fixing of the flange members 16 and 18 at both ends, it is continuously performed by a series of operations. From the drum main body 14 and the flange members 16 and 18 having the above error, it is possible to easily and quickly obtain the photosensitive drum 12 that satisfies the high accuracy requirement.
[0027]
Various methods for rotating the drum body about its axis and measuring methods for obtaining the eccentric direction of the drum body are conceivable and are not limited to the methods of the embodiments.
The present invention is naturally applicable to a cantilever type photosensitive drum in which a flange member is provided only at one end in the longitudinal direction of the drum body.
[0028]
The photosensitive drum 12 used in the present invention comprises a photosensitive layer 1404 on a conductive support (tubular body 1402). The photosensitive layer 1404 includes a so-called multilayer type in which a charge generation layer and a charge transport layer are separately formed, and a single layer type composed of a single layer. The body is preferred. In particular, in a full-color electrophotographic photosensitive member that requires high sensitivity, a laminated electrophotographic photosensitive member is preferably used. Hereinafter, the photosensitive drum 12 will be described by taking a laminated type as an example.
Examples of the charge generating agent contained in the charge generating layer include selenium and its alloys, arsenic-selenium, cadmium sulfide, zinc oxide, other inorganic photoconductors, phthalocyanines, azo series, quinacridone series, polycyclic quinone series, perylene. Organic pigments such as those based on Indigo, squarylium dyes, azurenium dyes, thiapyrylium dyes, and benzimidazoles can be used. In particular, metals such as copper, indium chloride, potassium chloride, tin, oxytitanium, zinc, vanadium, or phthalocyanines coordinated with oxides or chlorides, metal-free phthalocyanines, or monoazo, bisazo, trisazo, polyazos Azo pigments such as are preferred. Of these, azo pigments or phthalocyanines are more preferable, and so-called Y-type oxytitanium phthalocyanine is particularly preferable because high sensitivity can be obtained. The charge generating agent may be used alone or in combination of two or more. For example, a mixture of so-called Y-type oxytitanium phthalocyanine and so-called β-type oxytitanium phthalocyanine or α-type oxytitanium phthalocyanine may be used as the charge generator.
[0029]
The so-called Y-type oxytitanium phthalocyanine has a maximum diffraction peak at a Bragg angle (2θ ± 0.2) of 27.3 ° in X-ray diffraction by CuKα rays. This crystalline oxytitanium phthalocyanine is generally referred to as Y-type or D-type. For example, FIG. 2 of JP-A-62-67094 (referred to as type II in the same publication), Fig. 1 of JP-A-2-8256, Fig. 1 of JP-A-64-82045, Journal of Electrophotographic Society Vol. 92 (issued in 1990), No. 3, pages 250-258 (in the same publication) (Referred to as Y-type). This crystalline oxytitanium phthalocyanine is characterized by having a maximum diffraction peak at 27.3 °, but normally has peaks at 7.4 °, 9.7 °, and 24.2 °.
The intensity of the diffraction peak may vary depending on the crystallinity, the orientation of the sample, and the measurement method, but in the measurement by the Bragg-Brendano concentration method usually used when performing X-ray diffraction of the powder crystal, The Y-type oxytitanium phthalocyanine has a maximum diffraction peak at 27.3 °. In addition, when measured by a thin film optical system (generally called thin film method or parallel method), 27.3 ° may not be the maximum diffraction peak depending on the state of the sample. This is probably because it is oriented in the direction.
[0030]
Various solvents may be used as a dispersion medium for the charge generating agent. For example, ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran and 1,2-dimethoxyethane; ketones such as acetone and methyl ethyl ketone; esters such as methyl acetate and ethyl acetate; alcohols such as methanol, ethanol and propanol alone Alternatively, two or more kinds can be mixed and used.
The amount of the dispersion medium to be used may be any amount as long as the dispersion can be sufficiently performed and an effective amount of the charge generator is contained in the dispersion, and usually 3 to 20 wt as the concentration of the charge generator in the dispersion at the time of dispersion. %, More preferably about 4 to 20 wt%.
As the binder resin used for the charge generation layer, polyvinyl polymers such as polyvinyl butyral, polyvinyl acetal, polyester, polycarbonate, polystyrene, polyester carbonate, polysulfone, polyimide, polymethyl methacrylate, funol resin, butyral resin, polyvinyl chloride, and the like The copolymer, phenoxy, epoxy, silicone resin, etc., and these partially crosslinked cured products can be used alone or in combination of two or more.
[0031]
As a method for mixing the binder resin and the charge generating particles, for example, a method of dispersing the charge generating particles as a powder or a polymer solution at the same time while dispersing the charge generating particles, or dispersing the dispersion of the binder resin. Any method such as a method of mixing in a polymer solution, or a method of mixing a polymer solution in a dispersion, may be used.
Next, the dispersion obtained here may be diluted with various solvents in order to obtain liquid properties suitable for coating. As such a solvent, the solvent illustrated as the said dispersion medium can be used, for example. The ratio between the charge generating agent and the binder resin is not particularly limited, but generally the charge generating agent is used in the range of 5 to 500 parts by weight with respect to 100 parts by weight of the resin.
[0032]
Examples of the charge transfer agent contained in the charge transfer layer include 2,4,7-trinitrofluorenone, tetracyanoxydimethane and other electron withdrawing substances, selbazole, indole, imidazole, oxazole, pyrazole, oxadiazole. , Electron-donating substances such as heterocyclic compounds such as pyrazoline and thiadiazole, aniline derivatives, hydrazone compounds, aromatic amine derivatives, stilbene derivatives, and polymers having groups of these compounds in the main chain or side chain. . For the charge transfer layer, the same binder resin or the like as the charge generation layer can be used. In particular, it is preferable to use a binder resin having high compatibility with the charge transfer layer. The dispersion for the charge transfer layer is prepared so that the ratio of the charge transfer agent to the binder resin ranges from 5 to 500 parts by weight of the charge transfer substance with respect to 100 weight of the binder resin.
[0033]
Using the dispersion prepared as described above, a charge generation layer is formed on a conductive support, and a charge transfer layer is laminated thereon to form a photosensitive layer 1404. In the case where the charge generation layer is laminated with the charge transfer layer to form the photosensitive layer 1404, the range of 0.1 μm to 10 μm is preferable, and the thickness of the charge transfer layer is preferably 10 to 40 μm.
The conductive support of the electrophotographic photosensitive member used in the present invention is not particularly limited, but aluminum or an aluminum alloy is preferably used.
Examples of the material of the aluminum conductive support include pure aluminum such as JIS1050, JIS1070, and JIS1080, AL-Mg alloy, AL-Cu alloy, AL-Si alloy, AL-Mg-Si alloy, and AL. Examples include various aluminum alloys such as a Cu—Si based alloy, more preferably JIS 3003 which is an AL—Mn based alloy, JIS 6063 which is an AL—Si based alloy, and the like. In the present invention, the term “aluminum” generally represents a general term including an aluminum alloy unless it is expressed separately from an aluminum alloy.
[0034]
Although the manufacturing method of these aluminum conductive supports is not particularly limited, an aluminum billet is processed into an extruded tube by a porthole method, a mandrel method, etc., and then a cylinder having a predetermined thickness and outer diameter is obtained. It can be made by drawing, impacting, ironing, or mirroring by cutting. Since drawing oil, cutting oil, rust preventive oil, various dusts in the air, and the like adhere to the surface of the conductive support, the cleaning treatment is usually performed before the photoconductive layer is formed.
A conductive support manufactured by a known method cannot be expected to be a perfect cylindrical shape, and there is a deviation of several μm to several tens of μm, including uneven thickness of the material and bending. It is also conceivable to increase the accuracy of the electrophotographic photosensitive member by reducing this shake. However, it is very expensive and not always practical.
A known barrier layer as commonly used may be provided between the conductive support and the charge generation layer. A surface protective layer may be provided on the outer surface of the photosensitive layer 1404.
[0035]
Examples of barrier layers include inorganic layers such as anodized films, aluminum oxide, and aluminum hydroxide, and organic layers such as polyvinyl alcohol, casein, polyvinyl pyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, and polyamide. used. The barrier layer is most effectively used in the range of 0.1 μm to 20 μm, preferably 0.1 μm to 10 μm.
The total thickness of the charge generation layer, charge transfer layer, and protective layer (hereinafter referred to as “photosensitive layer 1404” in this column) provided on the conductive support is preferably set to about 10 μm to 50 μm. In particular, when the photosensitive layer 1404 is thick, unevenness of the photosensitive layer 1404 itself is likely to occur, and the present invention is more preferably applied. The thickness of the photosensitive layer 1404 is preferably 20 to 50 μm, more preferably 25 to 50 μm, and particularly preferably 30 to 50 μm.
[0036]
Examples of the image forming apparatus using the photosensitive drum 12 of the present invention include a printer, a copying machine, and a facsimile.
Since the electrophotographic photosensitive member of the present invention is configured with less shake, it can be suitably used particularly for full-color printers, copiers, facsimiles, and the like.
The image forming apparatus includes a storage device (1), a storage device (2), a storage device (3), a storage device (4), a hopper, a stacker, a conveyance path for conveying a recording medium (paper), and a fixing unit. is there. Each of the storage devices {circle around (1)} to {circle around (4)} is provided with a developing unit (charging device, developing device, fixing device, static eliminator, cleaner), electrophotographic photosensitive member, and optical unit (exposure device).
The recording apparatus (1) includes a yellow (hereinafter referred to as “Y”) developing unit, an electrophotographic photosensitive member, and an optical unit. The recording apparatus (2) includes a magenta (hereinafter referred to as “M”) developing unit, an electrophotographic photosensitive member, and an optical unit. The recording apparatus (3) includes a cyan (hereinafter referred to as “C”) developing unit, an electrophotographic photosensitive member, and an optical unit. The recording apparatus (4) includes a black (hereinafter referred to as “K”) developing unit, an electrophotographic photosensitive member, and an optical unit.
[0037]
The hopper provides paper to the conveyance path. The stacker is a stack for storing printed sheets. The conveyance path conveys paper. The fixing unit fixes an image transferred from the electrophotographic photosensitive member to a sheet.
The developing unit applies a developing material (toner corresponding to each recording device of Y, M, C, and K) to the latent image formed on the electrophotographic photosensitive member and performs development. The electrophotographic photosensitive member is to transfer an image developed by the developing unit onto a sheet after creating an electrostatic latent image corresponding to the image to be obtained. The optical unit scans the electrophotographic photosensitive member with a laser beam modulated by each image data (information) to form an electrostatic latent image.
[0038]
The operation of the image forming apparatus will be described below.
The surface of the electrophotographic photosensitive member is charged substantially uniformly using a charger such as corotron or strolocolon. The host computer sends a print command based on information such as images and characters. When printing is instructed from the host computer, if the printer is not ready, it responds with the device busy, and if the printer is ready, it makes a data request. When Y data, M data, C data, and K data are sent from the host computer, the recording devices {circle around (1)} to {circle around (4)} of the image forming apparatus are lasers modulated by the optical unit according to the respective color data. Each electrophotographic photosensitive member is scanned with light. Thereby, the electric charge is removed from the portion on the electrophotographic photosensitive member irradiated with the laser beam, and an electrostatic latent image is formed on the electrophotographic photosensitive member.
[0039]
Thereafter, a developing material such as toner is applied to the electrostatic latent image formed on the electrophotographic photosensitive member in each developing unit to form a visible image on the electrophotographic photosensitive member. Next, the sheet is superimposed on the visible image, a charge opposite to that of the developer is applied to the sheet with a charger from the back of the sheet, and the visible image is transferred to the sheet by electrostatic force. The transferred visible image is fused with heat or pressure to form a permanent image. This operation is performed for each color of Y, M, C, and K on one sheet to obtain a color image on the sheet. On the other hand, the latent image charge on the electrophotographic photosensitive member after transfer is neutralized by light. Further, the developer such as residual toner remaining without being transferred is removed by a cleaner. By repeating the above process, image formation is continuously performed.
[0040]
In addition, the sheets are placed one by one in the conveyance path by the hopper, and the developed images of the respective colors posted on the electrophotographic photosensitive member are sequentially transferred onto the sheets while the sheets are conveyed by the belt-shaped conveyance means. Then, the image transferred on the paper is fixed by the fixing unit, and finally the printed paper is stacked and stored by the stacker.
As an image forming apparatus, a developer (each color toner) attached on each electrophotographic photosensitive member is transferred to one intermediate transfer belt at one end, and each color toner is combined on the intermediate transfer belt. Then, an image may be formed on a sheet using a transfer unit.
[0041]
【The invention's effect】
As is apparent from the above description, according to the photosensitive drum of the present invention, a photosensitive drum with less variation in the eccentric direction can be obtained from the drum main body and the flange member having an error in manufacturing accuracy.
Further, according to the method for assembling the photosensitive drum of the present invention, a photosensitive drum satisfying high accuracy requirements can be obtained easily and in a short time from the drum body and the flange member having an error in manufacturing accuracy.
Further, according to the image forming apparatus of the present invention, a clear image free from distortion and blur such as misregistration and color misregistration can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a photosensitive drum.
FIG. 2A is an explanatory diagram of a processing error of a drum body, and FIG. 2B is an explanatory diagram of a processing error of a flange member.
FIG. 3 is an explanatory diagram when a contact surface of a flange member is a reference surface.
4A is a front view of an assembling apparatus for assembling a photosensitive drum, and FIG. 4B is a side view of a state in which the drum body is supported by a V block.
[Explanation of symbols]
12 Photosensitive drum 14 Drum body 1402 Tube 1406 Fitting hole 16, 18 Flange member 1602, 1802 Ring plate portion 1604, 1804 Bearing portion 1606, 1806 Abutting surface

Claims

Consists of a drum body and a flange member attached to the longitudinal end of the drum body,
The drum body includes a photosensitive layer formed on an outer peripheral surface thereof, and a fitting hole formed in an end portion in the longitudinal direction.
The flange member includes an annular plate portion that is fitted and fixed in the fitting hole, and a bearing portion that is located at the center of the annular plate portion,
The center of the outer peripheral surface of the drum main body is eccentric with respect to the center of the inner peripheral surface of the fitting hole at the end of the drum main body, and the center of the annular plate portion is eccentric with respect to the center of the bearing portion of the flange member. A photosensitive drum,
The eccentric direction of the drum body, which is the direction in which the center of the outer peripheral surface of the drum body is eccentric with respect to the center of the inner peripheral surface of the fitting hole at the end of the drum body, and the center of the bearing portion of the flange member center of the ring plate portion and the eccentric direction of the flange member is a direction in which eccentric rings plate portion of the flange member so that the same orientation is fixed is fitted into the fitting hole of the drum body Te,
A photosensitive drum characterized by the above.

Consists of a drum body and a flange member attached to the longitudinal end of the drum body,
The drum body includes a photosensitive layer formed on an outer peripheral surface thereof, and a fitting hole formed in an end portion in the longitudinal direction.
Each flange member includes an annular plate portion that is fitted and fixed in the fitting hole, a bearing portion that is located at the center of the annular plate portion, and a base portion of the annular plate portion that is fitted with the annular plate portion. An annular abutting surface that abuts against the end surface of the drum body when fitted into the fitting hole,
The center of the outer peripheral surface of the drum main body is eccentric with respect to the center of the inner peripheral surface of the fitting hole at the end of the drum main body, and with respect to a virtual plane including the abutting surface passing through the center of the bearing portion of the flange member A photosensitive drum in which the central axis of the bearing portion is inclined with respect to a perpendicular line perpendicular to each other,
When the perpendicular perpendicular to the imaginary plane and the central axis of the bearing portion intersect within the bearing portion, the direction in which the axis is displaced from the perpendicular on the outer side of the photosensitive drum as viewed from the bearing portion. When the inclination direction of the central axis of the flange member is set, the drum body has a direction in which the center of the outer peripheral surface of the drum body is eccentric with respect to the center of the inner peripheral surface of the fitting hole at the end of the drum body. The direction of eccentricity and the direction of inclination of the central axis of the flange member are reversed , and the ring plate of the flange member is fitted into the fitting hole of the drum body, and the abutting surface is abutted against the end surface of the drum body and fixed. Being
A photosensitive drum characterized by the above.

The fitting hole are respectively formed at both longitudinal ends of the drum body, said flange member are respectively attached to the fitting hole of the longitudinal ends of the drum main body, the eccentric direction of the drum body, the drum 3. The photosensitive drum according to claim 1, wherein the center of the outer peripheral surface of the drum main body is eccentric with respect to an axis connecting the centers of the inner peripheral surfaces of the fitting holes at both ends of the main body. .

Consisting of a drum body and two flange members attached to both ends in the longitudinal direction of the drum body,
The drum body includes a photosensitive layer formed on an outer peripheral surface thereof, and fitting holes formed on both ends in the longitudinal direction,
Each flange member includes an annular plate portion that is fitted and fixed in the fitting hole, and a bearing portion that is located at the center of the annular plate portion,
Wherein is eccentric center of the outer peripheral surface of the drum body with respect to the axis connecting the centers of the inner peripheral surface of the fitting hole of the both ends of the drum main body, said flange ring plate portion with respect to the center of the bearing portion of the member Is a method of assembling a photosensitive drum whose center is eccentric,
The eccentric direction of the flange member, which is the direction in which the center of the annular plate part is eccentric with respect to the center of the bearing part of the flange member in advance , is determined,
The center of the outer peripheral surface of the drum body is centered on the axis connecting the centers of the inner peripheral surfaces of the fitting holes at both ends of the drum body on a rotating device capable of rotating the drum body about its axis. Find the eccentric direction of the drum body, which is the eccentric direction,
After obtaining the eccentric direction of the drum body, the drum body is rotated on the rotating device, and the eccentric direction of the drum body is matched with a predetermined direction,
Each annular plate portion of the flange member to the eccentric direction of each flange member relative to the predetermined direction to the same direction into the fitting hole of the drum body and adapted to fitted and fixed,
And a method for assembling the photosensitive drum.

Consisting of a drum body and two flange members attached to both ends in the longitudinal direction of the drum body,
The drum body includes a photosensitive layer formed on an outer peripheral surface thereof, and fitting holes formed on both ends in the longitudinal direction,
Each flange member includes an annular plate portion that is fitted and fixed in the fitting hole, a bearing portion that is located at the center of the annular plate portion, and a base portion of the annular plate portion that is fitted with the annular plate portion. An annular abutting surface that abuts against the end surface of the drum body when fitted into the fitting hole,
Wherein is eccentric center of the outer peripheral surface of the drum body with respect to the axis connecting the centers of the inner peripheral surface of the fitting hole of the both ends of the drum body, the street abutment surface center of the bearing portion of said flange member A method of assembling a photosensitive drum in which a central axis of a bearing portion is inclined with respect to a perpendicular perpendicular to a virtual plane including
When the perpendicular perpendicular to the imaginary plane and the central axis of the bearing portion intersect within the bearing portion, the direction in which the axis is displaced from the perpendicular on the outer side of the photosensitive drum as viewed from the bearing portion. When the inclination direction of the central axis of the flange member is determined, the inclination direction of the central axis of the bearing portion of the flange member is obtained in advance,
The center of the outer peripheral surface of the drum body is centered on the axis connecting the centers of the inner peripheral surfaces of the fitting holes at both ends of the drum body on a rotating device capable of rotating the drum body about its axis. Find the eccentric direction of the drum body, which is the eccentric direction,
After obtaining the eccentric direction of the drum body, the drum body is rotated on the rotating device, and the eccentric direction of the drum body is matched with a predetermined direction,
Fitted respectively to the fitting hole of the predetermined drum body the ring plate portion of the central axis each flange member inclined direction in the opposite direction of the bearing portion of the flange member with respect to the direction, the end face of the drum body the abutment surface I tried to fix it against the
And a method for assembling the photosensitive drum.

6. The method of assembling a photosensitive drum according to claim 4, wherein the eccentric direction of the drum body is obtained at the center in the longitudinal direction of the drum body.

5. The method of assembling a photosensitive drum according to claim 4, wherein the flange member is made of synthetic resin and is formed by molding, and the eccentric direction of the flange member is known in advance.

6. The method for assembling a photosensitive drum according to claim 5, wherein the flange member is made of a synthetic resin, is formed by molding, and an inclination direction of a central axis of the bearing portion is known in advance.

An image forming apparatus using the photosensitive drum according to claim 1.