JP2004077650A - Electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic apparatus which improves electrostatic charging ability, reduces unevenness in electrostatic charging ability, ensures high durability and enhances image quality. <P>SOLUTION: The electrophotographic apparatus comprises charge eliminating, electrostatic charging, imagewise exposing, developing and transferring means, wherein the electrostatic charging means is a contact charging means, a plurality of contact charging means are arranged along the rotative direction of a photoreceptor, the photoreceptor includes a photoconductive layer comprising a non-monocrystalline material based on silicon and containing at least hydrogen and/or halogen atoms, an upper blocking layer comprising a non-monocrystalline material based on silicon and carbon and containing a group 13 atom of a periodic table, and a surface layer comprising a non-monocrystalline material having at least carbon as a component, and a dynamic hardness of the surface layer is 4,900-12,750 N/mm<SP>2</SP>(500-1,300 kgf/mm<SP>2</SP>). <P>COPYRIGHT: (C)2004,JPO

Description

作製した感光体を、電子写真装置を元にした空回転機（キヤノン製ｉＲ−５０００　を実験用に負帯電システムに改造し、現像器、クリーナー、転写材などを取り去った物）にセットして、電位特性の評価を行なった。
【０１７２】
帯電器としては、導電性ローラ帯電器（移動方向上流側）と磁気ブラシ帯電器（移動方向下流側）とを用いた。２つの帯電器が為す角度を　２５度とした。
【０１７３】
磁気ブラシ帯電器には−５５０Ｖの直流電圧を印加し、更に交番電圧（１．２ｋＶｐｐ、１．０ｋＨｚ）を印加した。
【０１７４】
帯電用磁性粒子はフェライト表面を酸化、還元処理して抵抗調整を行ない、平均粒径は　２５μｍ、飽和磁化は　２．５×１０^−１Ｗｂ／ｍ^２（２００ｅｍｕ／ｃｍ^３）、抵抗値は　１．９×１０^６Ωであった。なお、抵抗値は、底面積が　２２８ｍｍ^３の金属セルに帯電用磁性粒子を２ｇ入れた後　６５０ｋＰａ（６．６ｋｇｆ／ｃｍ^２）で加重し、１００Ｖの電圧を印加して測定した。また、導電性ローラーには−１０００Ｖの電圧を印加した。なお、導電性ローラ帯電器の材質は、芯金としてはステンレスを用い、弾性体層としては、ウレタンなどを主に用いた発泡ソリッド弾性体に、カーボン、ＴｉＯ_２、ＺｎＯなどの金属酸化物を加えたものであり、体積抵抗率は１Ｅ４〜１Ｅ１３Ω・ｃｍとしたものを用いた。
【０１７５】
この際、プロセススピードは　２００〜７００ｍｍ／ｓとした。このことにより、ｔ／Ｓは最大で　８．０２μｍ／ｓであった。また除電光に波長　６６０ｎｍのＬＥＤを用い、それぞれのプロセススピードにおける光量を４　ｌｘ・ｓとした。帯電能の測定は、電子写真装置の現像器位置にセットした表面電位計（ＴＲＥＫ社　Ｍｏｄｅｌ　３４４）の電位センサーにより感光体の表面電位を測定し、この値を帯電能とした。また、この帯電能を軸方向に　１８点測定し、軸方向、周方向をあわせて面内における帯電能のムラを評価した。
【０１７６】
以上、得られた結果を図６、図７に示す。
【０１７７】
《比較実験例１》
実験例１で作製した感光体を、実験例１と電子写真装置を元にした空回転機にセットして、電位特性の評価を行なった。
【０１７８】
帯電器としては、コロナ帯電器、磁気ブラシ帯電器、の２通りで行なった。
【０１７９】
コロナ帯電器は帯電器幅　３３ｍｍ、グリッド電圧−６００Ｖとし、帯電ワイヤーに流す一次電流は−１５００μＡ程度とした。また、磁気ブラシ帯電器には−５５０Ｖの直流電圧を印加し、更に交番電圧（１．２ｋＶｐｐ、１．０ｋＨｚ）を印加した。磁性粒子の抵抗値は　１．９×１０^６Ω、他の条件も実験例１と同じであった。
【０１８０】
この際、プロセススピードは　２００〜７００ｍｍ／ｓとし、除電光に波長　６６０ｎｍのＬＥＤを用い、それぞれのプロセススピードにおける光量を４　ｌｘ・ｓとした。
【０１８１】
以上のような構成で、実験例１と同様に帯電能、帯電能ムラを評価した。
【０１８２】
得られた結果を、実験例１の結果とあわせて図６、図７に示す。
【０１８３】
図６には、プロセススピードに対する帯電能の推移を示している。３種類の帯電器とも、プロセススピードが　２００ｍｍ／ｓの時の帯電能（全ての帯電器とも、４００Ｖ前後）を１とし、この値に対する増減を相対値で示してある。コロナ帯電器では、プロセススピードの増加と共に帯電能が減少していく。これは帯電器が定電流型であって、電荷量がプロセススピードで決まる帯電器の通過時間との積になるため、通過時間が減ることにより帯電能が単調に減少してしまう。これに対し、接触帯電方式である磁気ブラシ帯電器、導電性ローラー＋磁気ブラシ帯電器では、定電圧型のため、プロセススピードに対する依存性が極めて小さい。加えて、接触帯電方式では、プロセススピードが遅くなると帯電能が逆に落ちてしまう。これは感光体の暗減衰がａ−Ｓｉ系の感光体では比較的大きいためである。
【０１８４】
また、磁気ブラシ帯電器だけの場合に比べ、実験例１の導電性ローラー＋磁気ブラシの系では、プロセススピードが　２００ｍｍ／ｓのときよりも大きく帯電能が向上している。これは多段式の帯電器を用いたことによるものと思われる。つまり、導電性ローラーによって前露光キャリアが十分に吐き出され、磁気ブラシ帯電器による帯電が非常に効率よく行なわれたためと考えられる。
【０１８５】
また、図７は、プロセススピードに対する帯電能の周方向ムラ（単位：Ｖ）を表している。図７を見ると、やはり定電圧型である接触帯電方式は、周ムラ抑制に効果的であることが判る。更に、実験例１のように多段式の接触帯電にすることによって、周ムラが更に抑制されることが示されている。
【０１８６】
図６、図７より、帯電方式としては多段式の接触帯電方式を用いた場合、帯電能、そのムラ、共に最も好ましく、更にプロセススピードが　３００ｍｍ／ｓ以上の領域では帯電能の著しい向上が見られ、本発明の効果がより好適に得られることが判った。
【０１８７】
《実験例２》
実験例１と同様に図５に示す真空処理装置を用い、直径　８０ｍｍの鏡面加工を施したアルミニウムシリンダー（基体）上に、下部阻止層、光導電層、上部阻止層、表面層をこの順で作成し、電子写真感光体を完成させた。このとき、表１に示す条件で下部阻止層、光導電層を作成し、表２に示す条件で上部阻止層を、表３に示す条件で表面層を作成し、これらの組み合わせによる種々の電子写真感光体を作成した。なお、上部阻止層と表面層との間には、実験例１と同様にガス流量や電力などをなだらかに変化させる変化領域を設けてある。
【０１８８】
【表２】

【０１８９】
【表３】

上部阻止層は表２の範囲内で可変し、Ａ〜Ｆの６種類の感光体を作成した。添加するボロン量に関しては、炭素とシリコンの組成比によって価電子制御の制御性が異なるため、炭素を増やした場合にはボロン量を増やす必要がある。これは別途、膜の抵抗値を測定しながらボロン量を適宜調整する実験を行って決定している。得られた膜はそれぞれ表４に挙げたような組成であることがＳＩＭＳによる測定で明らかとなった。表面層の組成Ｃ／（Ｓｉ＋Ｃ）は　０．７５　であった。
【０１９０】
【表４】

作製した感光体を、電子写真装置を元にした空回転機（キヤノン製ｉＲ−５０００　を実験用に負帯電システムに改造し、現像器、クリーナー、転写材などを取り去った物）にセットして、実験例１と同様に電位特性の評価を行なった。
【０１９１】
帯電器としては、実験例１と同様の導電性ローラ帯電器と磁気ブラシ帯電器との多段帯電器で行なった。２つの帯電器が為す角度は　２５度とし、磁性体の種類や印加電圧などは実験例１と同等とした。また、プロセススピードは　３５０ｍｍ／ｓ固定とし、除電光なども実験例１と同等とした。
【０１９２】
以上、得られた結果を図８、図９に示す。
【０１９３】
《比較実験例２》
実験例２で作成したＡ〜Ｆの感光体を、実験例２と同様の電子写真装置を元にした空回転機にセットして、実験例２と同様に電位特性の評価を行なった。
【０１９４】
帯電器としては、コロナ帯電器、磁気ブラシ帯電器２通りで行なった。磁性体の種類や印加電圧などは実験例１と同等とした。また、プロセススピードは　３５０ｍｍ／ｓ固定とし、除電光なども実験例１と同等とした。
【０１９５】
以上、得られた結果を実験例２の結果とあわせて図８、図９に示す。
【０１９６】
図８、図９では、感光体Ａでの結果を基準（＝１）とし、それぞれ相対値で表している。つまり、例えば図８の点線で表したコロナ帯電では、感光体Ａとコロナ帯電とを組み合わせたプロセスでの帯電能の値を１とし、感光体Ｂ〜Ｆとコロナ帯電とを組み合わせた場合の相対値をプロットしている。同様に、破線で示した磁気ブラシ帯電器単体のプロットも、実線で表した多段方式のプロットも、それぞれ感光体Ａとの組み合わせた場合の値を基準としている。
【０１９７】
図８、図９からわかるように、接触帯電においては感光体Ｂ〜Ｆは全て感光体Ａに比べて帯電能が向上し、帯電能ムラが改善する方向である。しかし、コロナ帯電においては向上や改善の幅が小さい。また、接触帯電であっても、多段方式である導電性ローラー帯電器と磁気ブラシ帯電器との組み合わせが最も帯電能向上、ムラ改善の効果が高い。この理由はわかっていないが、本発明の感光体層構成と本発明の多段接触帯電プロセスのマッチングが非常に良好であるためではないかと考えている。
【０１９８】
以上の結果から、上部阻止層を設ける場合には、そのシリコン−炭素組成、周期律表第１３族原子のシリコンに対する濃度が適正である場合に、本発明の多段帯電方式とのマッチングが最も良好であり、本発明の効果がより一層得られることが判った。
【０１９９】
《実験例３》
実験例１と同様に図５に示す真空処理装置を用い、直径　８０ｍｍの鏡面加工を施したアルミニウムシリンダー（基体）上に、下部阻止層、光導電層、上部阻止層、表面層をこの順で作成し、電子写真感光体を完成させた。このとき、表１に示す条件で下部阻止層、光導電層を作成し、表５に示す条件で上部阻止層を、表６に示す条件で表面層を作成し、これらの組み合わせによる種々の電子写真感光体を作成した。なお、上部阻止層と表面層との間には、実験例１と同様にガス流量や電力などをなだらかに変化させる変化領域を設けてある。
【０２００】
【表５】

【０２０１】
【表６】

ａ−Ｃからなる表面層は表６の範囲内で可変し、Ｇ〜Ｋの５種類の感光体を作成した。硬度の範囲を広く取るために本実験例ではガスの流量と電力の値を振ることで実現している。表面層の硬度に関しては、電力以外の要因もあるが、電力に関しては高い方が高硬度にしやすく、低い方が比較的硬度が低くなる傾向がある。
【０２０２】
また、これとは別に、表５に示した上部阻止層のみについて同一の条件で膜を堆積させたサンプルを作成し、実験例１と同様に定量分析を行なった。上部阻止層の組成Ｃ／（Ｓｉ＋Ｃ）は０．３２、Ｂ量はシリコンに対して　３０００ｐｐｍであった。
【０２０３】
さらに、表５、表６に示した各層と同一条件の単独層のサンプルをＳｉウエハ上に堆積させ、ダイナミック硬度計（島津製作所製、ＤＵＨ−２０１）による測定にかけた。ここで、ダイナミック硬度測定に用いた圧子は、稜間角　１１５°の三角すい圧子（先端曲率半径　０．１μｍ以下）であり、ダイナミック硬度の値はこの圧子を使用して　０．９８ｍＮ（０．１ｇｆ）荷重になるまで圧子を押し込んだ時の値である。
【０２０４】
その結果、得られた膜はそれぞれ表７に挙げたようなダイナミック硬度であることが明らかとなった。
【０２０５】
ここで言うダイナミック硬度とは、その測定原理から、一般的によく用いられるビッカース硬度などのような塑性変形の定量化（圧子を押し込み、それによってついた跡の大きさを測って硬度を算出する方法）とは異なる。即ち、堆積した膜に圧子を微小量押し込むことによる変形を測定するため、膜の表面の粗さ形状の影響や弾性変形に相当する力も合わせて測定される。このように表面形状や弾性変形を含む硬度を指標としたことで、感光体が実際に曝される環境に対する耐久性、具体的には表面層としての削れ特性や、トナー、磁性粒子、ブレードとの摩擦特性などとの相関が取れると考えられる。
【０２０６】
【表７】

作製した感光体を、電子写真装置（キヤノン製ｉＲ−５０００　を実験用に負帯電システムに改造した物）にセットして、実際の複写操作を用いて耐久試験を行なった。
【０２０７】
帯電器としては、実験例１と同様の導電性ローラ帯電器と磁気ブラシ帯電器との多段帯電器を用いた。２つの帯電器が為す角度は　２５度とした。磁性体の種類や印加電圧などは実験例１と同等とした。また、プロセススピードは　４００ｍｍ／ｓ固定とし、除電光なども実験例１と同等とした。現像器、クリーナーに関してはｉＲ−５０００用のものを流用し、複写原稿としてはキヤノン製テストチャート（部品番号ＦＹ９−９０６０Ａ）を用い、環境試験室中で　２３℃、５０％の通常環境下にて再生紙（キヤノン製リサイクルペーパーＥＷ−５００）による通紙耐久試験を　１０万枚行なった。
【０２０８】
耐久試験後、クリーニング性の評価として、ベタ白画像（レーザー出力ゼロ）を出力し、得られた画像の汚れ具合を見た。定量的な判定のために、Ａ４画像中、汚れている面積を算出して比較した。
【０２０９】
次にムラ削れの評価として、まずレーザーパターンによるハーフトーン（ワンドットワンスペース）を出力し、画像上の濃度差を反射濃度計（マクベス社製）にて評価した。この濃度差は、最も削れている部分と削れていない部分との高低差を反映している。
【０２１０】
得られた結果を表９にしめす。
【０２１１】
《比較実験例３》
実験例３と同様に感光体Ｌを作成した。この際、表面層のみ表８に挙げた条件で作成した。
【０２１２】
得られた感光体の表面層の硬度測定による膜の硬度は　４１２０Ｎ／ｍｍ^２（４２０ｋｇｆ／ｍｍ^２）であった。
【０２１３】
【表８】

作製した感光体を、実験例３と同様の電子写真装置（キヤノン製ｉＲ−５０００　を実験用に負帯電システムに改造した物）にセットして、同様に　１０万枚の耐久試験を行なった。次に実験例３と同様の評価方法でクリーニング性、ムラ削れの度合いを評価した。
【０２１４】
得られた結果を表９に示す。なお、表９においては、比較実験例３で作成した感光体Ｌで得られた評価結果を基準とし、以下のような判断基準でランク付けを行なった。
【０２１５】
クリーニング性の評価においては汚れ部分の面積を、感光体Ｌでの値と比較し、以下のように４つに分類した。
【０２１６】
◎：感光体Ｌに比べて　汚れ部分の面積が２０％以上減少している
○：感光体Ｌに比べて　汚れ部分の面積が１０〜２０％減少している
△：感光体Ｌに比べて　汚れ部分の面積が１０％未満の差である（ほぼ同等である）
×：感光体Ｌに比べて　汚れ部分の面積が大きい
ムラ削れ量の評価においては表面層削れ量の最大値と最小値との差を、感光体Ｌでの値と比較し、以下のように４つに分類した。
【０２１７】
◎：感光体Ｌに比べて削れ量の差が２０％以上減少している
○：感光体Ｌに比べて削れ量の差が１０〜２０％減少している
△：感光体Ｌに比べて削れ量の差が１０％未満の差である（ほぼ同等である）
×：感光体Ｌに比べて削れ量の差が大きい
【０２１８】
【表９】

表９から判る通り、ダイナミック硬度が　４１２０Ｎ／ｍｍ^２（４２０ｋｇｆ／ｍｍ^２）である感光体Ｌと比較すると、硬度の大きい感光体Ｇ〜Ｋはいずれも削れムラが小さい、即ち最も削れた部分と最も削れなかった部分の段差が小さいことが判る。特に感光体Ｇ〜Ｉに関しては、削れムラだけでなく削れの絶対量も非常に少なかった。また、クリーニング性に関しては感光体Ｈ〜Ｋの全てにおいて感光体Ｌよりも改善している。一方、感光体Ｇに関しては感光体Ｌでの値と殆ど違わなかった。これは詳しくは不明であるが、以下のように考えている。非晶質炭化珪素であっても、非晶質炭素であっても共通して言えることは、膜を高硬度にするためには単位ガス量あたりの電力値を大きくする必要があるという点である。このように高いパワーがかかると、プラズマのセルフバイアスの効果（イオン衝撃）によって膜が硬くなると考えられている。その際、このイオン衝撃が大きくなりすぎると、表面にダメージが発生しやすくなると考えられ、このダメージによって表面性が変化し、クリーニング性の向上が阻害されたと考えている。このことから、本発明の効果を得るためには、表面層のダイナミック硬度が　４９００〜１２７５０Ｎ／ｍｍ^２（５００〜１３００ｋｇｆ／ｍｍ^２）であることが最も望ましいことが判った。
【０２１９】
《実験例４》
実験例１と同様に図５に示す真空処理装置を用い、直径　８０ｍｍアルミニウム円筒上に、コーニング社製　７０５９　ガラス基板（３８．１ｍｍ（１．５インチ）×２５．４ｍｍ（１インチ）×０．５ｍｍ）と直径２５．４ｍｍ（１インチ）のＳｉウエハを基板として設置した。ガラスやＳｉウエハが置かれる部分は水平に削られており、ガラスがアルミニウム円筒に密着するようにした。またガラスやＳｉウエハはステンレス製の爪で抑え、落下しないようにした。このような基板は、実験例１と同様に成膜前にヒータによって加熱され、表面が所定の温度になるように調整した。次に、表１０に示した条件で、ガス流量とその比、高周波電力の値を様々に変えて、表面層に当たる単層膜Ｍ〜Ｑを作成した。
【０２２０】
【表１０】

得られた膜は、実験例３と同様にダイナミック硬度計によって硬度を測定した。また、硬度測定された膜は二次イオン質量分析（ＳＩＭＳ）によって組成の定量が行なわれた。これらの測定結果を表１１に示す。
【０２２１】
表１１から、非晶質炭化珪素からなる表面層を作成する際、本発明において好適な硬度を得るためには、その組成Ｃ／（Ｓｉ＋Ｃ）の値が　０．７以上である場合が好ましいことが判った。
【０２２２】
《比較実験例４》
実験例４と同様に表面層に当たる単層膜Ｒを作成した。この際、表１０において、ＳｉＨ_４ガス、ＣＨ_４ガスをそれぞれ３３、６７ｍｌ／ｍｉｎ（ｎｏｒｍａｌ）とした。ＳＩＭＳによる測定で、表１１に示すように、組成Ｃ／（Ｓｉ＋Ｃ）が０．６５である膜であることが判った。この膜のダイナミック硬度を測定すると、ダイナミック硬度が　４１２０Ｎ／ｍｍ^２（４２０ｋｇｆ／ｍｍ^２）となり、十分な硬度は得られなかった。
【０２２３】
【表１１】

《実験例５》
実験例１と同様に図５に示す真空処理装置を用い、直径　１０８ｍｍの鏡面加工を施したアルミニウムシリンダー（基体）上に、下部阻止層、光導電層、上部阻止層、表面層をこの順で作成し、電子写真感光体を完成させた。このとき、表１に示す条件で下部阻止層、光導電層を作成し、表１２に示す条件で上部阻止層を、表１３に示す条件で表面層を作成し、これらの組み合わせによる種々の電子写真感光体を作成した。なお、上部阻止層と表面層との間には、実験例１と同様にガス流量や電力などをなだらかに変化させる変化領域を設けてある。
【０２２４】
【表１２】

【０２２５】
【表１３】

上部阻止層は表１２の範囲内で膜厚を可変し、０．０５、０．３、０．４　の３通りの厚さの上部阻止層を持つ感光体Ｓ、Ｔ、Ｕを作成した。上部阻止層の組成Ｃ／（Ｓｉ＋Ｃ）は　０．３６、Ｓｉに対するＢ量は　３０００ｐｐｍであった。表面層の組成Ｃ／（Ｓｉ＋Ｃ）は　０．７１　であった。
【０２２６】
作製した感光体を、電子写真装置を元にした空回転機（キヤノン製ＧＰ−６０５　を実験用に負帯電システムに改造し、現像器、クリーナー、転写材などを取り去った物）にセットして、実験例１と同様に電位特性の評価を行なった。
【０２２７】
帯電器は、実験例１と同様の導電性ローラ帯電器と磁気ブラシ帯電器との多段帯電器であり、磁性体の種類や印加電圧などは実験例１と同等とした。ここで、２つの帯電器を配置する角度を、１７度、３０度と変えることにより、帯電器間の時間Ｓ（秒）を変化させた。このとき、帯電器の配置角度が　１７度のものをプロセスＡ、３０度のものをプロセスＢとした。また、プロセススピードは　４５０ｍｍ／ｓ、５００ｍｍ／ｓの２通りとした。除電光などは実験例１と同等とした。
【０２２８】
以上、得られた結果を図１０　に示す。なお図１０　においては、最もｔ／Ｓ（μｍ／ｓ）の大きい条件で得られた評価結果を基準とし、以下のような判断基準でランク付けを行なった。即ち、感光体Ｕ（上部阻止層の厚さが　０．４μｍのもの）を用い、プロセスＡ（２つの帯電器がなす角が　１７度）と組み合わせ、プロセススピードが　５００ｍｍ／ｓの時、ｔ／Ｓは　１２．５となり最も大きい。この組み合わせでの結果を基準（＝１）とし、ｔ／Ｓと帯電能周ムラとの関係をプロットした。
【０２２９】
図１０　からわかるように、ｔ／Ｓが小さいほどムラ改善の効果が高く、特にｔ／Ｓが　１０以下の領域で改善効果が大きいのが判る。これは除電光キャリアの吐き出しがより完全に行なわれることを意味していると思われ、ｔ／Ｓを小さくするほど、本発明の感光体層構成と本発明の多段接触帯電プロセスのマッチングがより良好となることを示している。
【０２３０】
以上の結果から、上部阻止層を設ける場合には、上部阻止層の膜厚ｔ（μｍ）と２つの帯電器間を感光体が通過する時間Ｓ（ｓ）との間の関係ｔ／Ｓが小さいほどよく、特にこの値が　１０以下である場合に、本発明の効果が最も好適に得られることが判った。
【０２３１】
（実施例１）
図５に示す真空処理装置を用い、直径　８０ｍｍの鏡面加工を施したアルミニウムシリンダー（基体）上に、表１４　に示す条件で下部阻止層、光導電層、上部阻止層、表面層の順に膜の堆積を行って電子写真感光体を作成した。図５の反応容器５０２　の内径は　５００ｍｍ、アルミシリンダーの本数は６本、２つの高周波を　９０ＭＨｚ、５０ＭＨｚとした。それぞれの高周波電力は１：１で重畳した。
【０２３２】
なお、感光体作成前に、あらかじめ表１４　に示したそれぞれの層に対応する膜を作成し、定量分析を行っている。表１２　の条件では、上部阻止層のＣ／（Ｓｉ＋Ｃ）の値は約０．２５　であり、ボロン量はＳｉに対して約２０００ｐｐｍであり、表面層のＣ／（Ｓｉ＋Ｃ）の値は約０．８であることが、作成した膜の二次イオン質量分析法（ＳＩＭＳ）によって判明している。なお、上部阻止層の作成時には、密着性向上を狙って成膜中にヒーターの設定温度を　１０℃上昇させた。また、上部阻止層と表面層との間は、レーザーによる干渉を防止するために組成をなだらかに変化させた変化領域を設けてある。堆積レートと変化時間から換算して、およそ　２００ｎｍ程度と見積もられる。膜堆積中は基板ホルダーを回転させ、周方向でムラが生じないように満遍なく膜を堆積させた。
【０２３３】
【表１４】

作製した感光体を、電子写真装置を元にした改造機（キヤノン製ｉＲ−５０００を実験用に負帯電システムに改造した物）にセットして、電位特性の評価を行なった。
【０２３４】
帯電器としては、実験例１と同様の導電性ローラ帯電器と磁気ブラシ帯電器との多段帯電器とした。磁気ブラシ帯電器には−５５０Ｖの直流電圧を印加し、更に交番電圧（１．２ｋＶｐｐ、１．０ｋＨｚ）を印加した。磁性粒子の抵抗値は　１．９×１０^６Ω、他の条件も実験例１と同じであった。また、導電性ローラーには−１０００Ｖの電圧を印加した。
【０２３５】
この際、プロセススピードは　４００ｍｍ／ｓとし、２つの帯電器が為す角度は　２０度、除電光に波長　６６０ｎｍのＬＥＤを用い、光量を４　ｌｘ・ｓとした。また、現像器、クリーナーなどに関してはｉＲ−５０００　のものを流用した。
【０２３６】
現像器位置での帯電能は良好であり、周ムラも非常に少なく、磁気ブラシによる掃きムラも見られず、その他、感度、暗減衰、ゴースト、残留電位ともに良好であった。現像器を挿入してテストチャートによる画像評価を行なったが、画像品位も良好で、濃度ムラが殆ど見られず、かぶり、ボケなども全く見られなかった。
【０２３７】
次にこの電子写真装置を用い、１０℃、１５％の低温低湿環境、２３℃、５０％の通常環境、３３℃、９０％の高温高湿環境でそれぞれ５万枚ずつ通紙耐久試験を行なったが、ムラ削れ、クリーニング不良、画像流れによる画像欠陥などは全く見られず、良好な画像が継続して得られることが判った。
【０２３８】
（実施例２）
図５に示す真空処理装置を用い、直径　１０８ｍｍの鏡面加工を施したアルミニウムシリンダー（基体）上に、表１５　に示す条件で下部阻止層、光導電層、上部阻止層、表面層の順に膜の堆積を行って電子写真感光体を作成した。図５の反応容器５０２　の内径は　４００ｍｍ、アルミシリンダーの本数は３本、２つの高周波を　１００ＭＨｚ、７０ＭＨｚとした。それぞれの高周波電力は１：１で重畳した。
【０２３９】
なお、感光体作成前に、あらかじめ表１５　に示したそれぞれの層に対応する膜を作成し、定量分析を行っている。表１３　の条件では、上部阻止層のＣ／（Ｓｉ＋Ｃ）の値は約０．２７　であり、ボロン量はＳｉに対して約２４００ｐｐｍであり、表面層のＣ／（Ｓｉ＋Ｃ）の値は約０．７８　であることが、作成した膜の二次イオン質量分析法（ＳＩＭＳ）によって判明している。なお、上部阻止層の作成時には、密着性向上を狙って成膜中にヒーターの設定温度を　２０℃上昇させた。また、上部阻止層と表面層との間は、レーザーによる干渉を防止するために組成をなだらかに変化させた変化領域を設けてある。堆積レートと変化時間から換算して、およそ　２００ｎｍ程度と見積もられる。膜堆積中は基体ホルダーを回転させ、周方向でムラが生じないように満遍なく膜を堆積させた。
【０２４０】
【表１５】

作製した感光体を、電子写真装置を元にした改造機（キヤノン製ＧＰ−６０５を実験用に負帯電システムに改造した物）にセットして、電位特性の評価を行なった。
【０２４１】
帯電器としては、実験例１と同様の導電性ローラ帯電器と磁気ブラシ帯電器との多段帯電器とした。磁気ブラシ帯電器には−５５０Ｖの直流電圧を印加し、更に交番電圧（１．２ｋＶｐｐ、１．０ｋＨｚ）を印加した。磁性粒子の抵抗値は　１．９×１０^６Ω、他の条件も実験例１と同じであった。また、導電性ローラーには−１０００Ｖの電圧を印加した。
【０２４２】
この際、プロセススピードは　４５０ｍｍ／ｓとし、２つの帯電器の為す角度は　３０度、除電光に波長　６６０ｎｍのＬＥＤを用い、光量を４　ｌｘ・ｓとした。また、現像器、クリーナーなどに関してはＧＰ−６０５　のものを流用した。
【０２４３】
現像器位置での帯電能は良好であり、周ムラも非常に少なく、磁気ブラシによる掃きムラも見られず、その他、感度、暗減衰、ゴースト、残留電位ともに良好であった。現像器を挿入してテストチャートによる画像評価を行なったが、画像品位も良好で、濃度ムラが殆ど見られず、かぶり、ボケなども全く見られなかった。
【０２４４】
次にこの電子写真装置を用い、１０℃、１５％の低温低湿環境、２３℃、５０％の通常環境、３３℃、９０％の高温高湿環境でそれぞれ５万枚ずつ通紙耐久試験を行なったが、ムラ削れ、クリーニング不良、画像流れによる画像欠陥などは全く見られず、良好な画像が継続して得られることが判った。
【０２４５】
（実施例３）
図５に示す真空処理装置を用い、直径　６０ｍｍの鏡面加工を施したアルミニウムシリンダー（基体）上に、表１６　に示す条件で下部阻止層、光導電層、上部阻止層、表面層の順に膜の堆積を行って電子写真感光体を作成した。図５の反応容器５０２　の内径は　５００ｍｍ、アルミシリンダーの本数は７本、２つの高周波を　８０ＭＨｚ、６０ＭＨｚとした。それぞれの高周波電力は１：１で重畳した。
【０２４６】
なお、感光体作成前に、あらかじめ表１４　に示したそれぞれの層に対応する膜を作成し、定量分析を行っている。表１６　の条件では、上部阻止層のＣ／（Ｓｉ＋Ｃ）の値は約０．１９　であり、ボロン量はＳｉに対して約　１０００ｐｐｍであり、表面層のＣ／（Ｓｉ＋Ｃ）の値は約０．８５　であることが、作成した膜の二次イオン質量分析法（ＳＩＭＳ）によって判明している。なお、上部阻止層の作成時には、密着性向上を狙って成膜中にヒーターの設定温度を　１０℃上昇させた。また、上部阻止層と表面層との間は、レーザーによる干渉を防止するために組成をなだらかに変化させた変化領域を設けてある。堆積レートと変化時間から換算して、およそ　３００ｎｍ程度と見積もられる。膜堆積中は基体ホルダーを回転させ、周方向でムラが生じないように満遍なく膜を堆積させた。
【０２４７】
【表１６】

作製した感光体４本を、電子写真装置を元にした改造機（キヤノン製ＣＬＣ−５０００　をベースマシンとし、ａ−Ｓｉ用システムに改造した物）にセットして、電位特性の評価を行なった。
【０２４８】
帯電器としては、実験例１と同様の導電性ローラ帯電器と磁気ブラシ帯電器との多段帯電器とした。磁気ブラシ帯電器には−５５０Ｖの直流電圧を印加し、更に交番電圧（１．２ｋＶｐｐ、１．０ｋＨｚ）を印加した。磁性粒子の抵抗値は　１．９×１０^６Ω、他の条件も実験例１と同じであった。また、導電性ローラーには−１０００Ｖの電圧を印加した。
【０２４９】
この際、プロセススピードは　４００ｍｍ／ｓとし、２つの帯電器の為す角度は　２０度、除電光に波長　６６０ｎｍのＬＥＤを用い、光量を４　ｌｘ・ｓとした。また、現像器、トナー、クリーナーなどに関してはＣＬＣ−５０００　のものを流用した。
【０２５０】
各色の現像器位置での帯電能は良好であり、周ムラも非常に少なく、磁気ブラシによる掃きムラも見られず、その他、感度、暗減衰、ゴースト、残留電位ともに良好であった。また各色間の特性ムラも非常に少なかった。次に現像器を挿入してテストチャートによる画像評価を行なったが、画像品位も良好で、濃度ムラが殆ど見られず、かぶり、ボケなども全く見られず、高品位なフルカラー画像が得られた。
【０２５１】
次にこの電子写真装置を用い、１０℃、１５％の低温低湿環境、２３℃、５０％の通常環境、３３℃、９０％の高温高湿環境でそれぞれ５万枚ずつ通紙耐久試験を行なったが、ムラ削れ、クリーニング不良、画像流れによる画像欠陥などは全く見られず、良好な画像が継続して得られることが判った。
【０２５２】
【発明の効果】
以上説明したように本発明によれば、除電、帯電、潜像露光、現像、転写等により画像形成を行なう電子写真装置であって、
帯電手段が接触帯電手段であり、該感光体の移動方向に沿って複数段配置され、感光体が、
シリコンを母体とし少なくとも水素原子及び／又はハロゲン原子を含有した非単結晶材料からなる光導電層と、
シリコンと炭素を母体とし、周期律表第１３族原子を含有した非単結晶材料からなる上部阻止層と、
少なくとも炭素を構成要素として持つ非単結晶材料からなる表面層とを含み、該表面層のダイナミック硬度が　４９００〜１２７５０Ｎ／ｍｍ^２（５００〜１３００ｋｇｆ／ｍｍ^２）であること
によって、良好な帯電能と極めて小さい帯電能ムラが実現でき、且つドラムの削れが殆どなく、超寿命且つ高安定を実現でき、その他、感度、ゴースト、暗減衰などに代表される電気特性、画像特性も優れており、極めて良好な特性を高次元で同時に達成できる電子写真装置を提供できる。
【図面の簡単な説明】
【図１】本発明の電子写真装置を模式的に説明した図である。
【図２】本発明の帯電手段を模式的に説明する図である。
【図３】本発明の電子写真装置の他の例として、４つの感光体を用いたフルカラー電子写真装置を模式的に説明する図である。
【図４】本発明の電子写真装置に必須の感光体の層構成を説明するための、感光体の模式的断面図である。
【図５】本発明の電子写真装置に必須の感光体を作成に、好適に使用できる膜堆積装置の１つを模式的に表した図である。図５（ａ）・・・縦断面図、図５（ｂ）・・・横断面図。
【図６】実験例１、比較実験例１における、帯電能のプロセススピードに対する依存性を、３種類の帯電方式で比較した図である。
【図７】実験例１、比較実験例１における、帯電能ムラのプロセススピードに対する依存性を、３種類の帯電方式で比較した図である。
【図８】実験例２、比較実験例２における、上部阻止層の違いによる帯電能の相対値を、３種類の帯電方式で比較した図である。
【図９】実験例２、比較実験例２における、上部阻止層の違いによる帯電能ムラの相対値を、３種類の帯電方式で比較した図である。
【図１０】実験例５において、上部阻止層膜厚、帯電器配置、プロセススピードを変化させることによる、ｔ／Ｓに対する帯電能ムラの相対値を表した図である。
【符号の説明】
１０１　　　　　感光体
１０２　　　　　導電性ローラー帯電器
１０３　　　　　磁気ブラシ帯電器
１０４　　　　　現像器
１０５　　　　　転写紙供給系
１０６（ａ）　　転写帯電器
１０６（ｂ）　　分離帯電器
１０７　　　　　クリーニングユニット
１０８　　　　　搬送系
１０９　　　　　除電光源
１１０　　　　　ハロゲンランプ
１１１　　　　　原稿台
１１２　　　　　原稿
１１３　　　　　ミラー
１１４　　　　　ミラー
１１５　　　　　ミラー
１１６　　　　　レンズユニット
１１７　　　　　ＣＣＤユニット
１１８　　　　　レーザーユニット
１１９　　　　　ミラー
１２１　　　　　クリーニングブレード
１２２　　　　　レジストローラー
１２４　　　　　定着器
２０１　　　　　感光体
２０２　　　　　導電性ローラー帯電器
２０３　　　　　磁気ブラシ帯電器
２０４　　　　　固定マグネット
２０５　　　　　帯電スリーブ
２０６　　　　　帯電用磁性粒子
２０７　　　　　磁性粒子規制手段（ブレード）
２０８　　　　　導電性芯金
２０９　　　　　弾性体層
２１０　　　　　表面層
２１１，２１２　　　　　電流検知装置
２１３，２１４　　　　　バイアス装置
Ｐａ〜Ｐｄ　　　　　画像形成部
１ａ〜１ｄ　　　　　感光体
２ａ〜２ｄ　　　　　帯電ユニット
３ａ〜３ｄ　　　　　像露光装置
４ａ〜４ｄ　　　　　現像器
５ａ〜５ｄ　　　　　クリーナー
６ａ〜６ｄ　　　　　転写手段
７　　　　　　定着器
８　　　　　　中間転写体
９　　　　　　転写ベルト
１０　　　　　　転写帯電手段
１３　　　　　　レジストローラー
Ｍ　　　　　　記録材（紙など）
４０１　　　　　基体
４０２　　　　　下部阻止層
４０３　　　　　光導電層
４０４　　　　　上部阻止層
４０５　　　　　表面層
４０６　　　　　光導電層
４０７　　　　　光導電層
５０１　　　　　円筒状基体
５０２　　　　　反応容器
５０３　　　　　ガス導入管
５０４　　　　　カソード電極
５０５　　　　　排気配管
５０６　　　　　基体支持体
５０７　　　　　高周波電源
５０８　　　　　高周波電源
５０９　　　　　マッチングボックス
５１０　　　　　回転軸
５１１　　　　　モーター
５１２　　　　　ギア
５１３　　　　　高周波電力分岐部
５１５　　　　　シールド[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic apparatus that uses an electrophotographic photosensitive member that is sensitive to electromagnetic waves, develops an electrostatic latent image corresponding to a recorded image with a developer, and records the image on paper or the like. In particular, the present invention relates to an electrophotographic apparatus characterized by using an amorphous silicon (hereinafter a-Si) photoconductor as an electrophotographic photoconductor and using a plurality of contact charging members as a charging method.
[0002]
[Prior art]
In the field of image formation, a photoconductive material for forming a photoreceptive layer in a photoreceptor has high sensitivity, a high SN ratio [photocurrent (Ip) / dark current (Id)], and conforms to the spectral characteristics of an electromagnetic wave to be irradiated. It is required to have such characteristics as having a stable absorption spectrum, fast photo-responsiveness, having a desired dark resistance value, and being harmless to the human body during use. In particular, in the case of an electrophotographic photosensitive member incorporated in an electrophotographic apparatus used as an office machine in an office, the above-described non-pollutability at the time of use is important.
[0003]
A-Si is a photoconductive material exhibiting excellent properties in this respect, and is attracting attention as a light receiving member of an electrophotographic photosensitive member.
[0004]
Such a photoreceptor is generally prepared by heating a conductive substrate to 50 ° C. to 350 ° C., and applying a vacuum deposition method, a sputtering method, an ion plating method, a thermal CVD method, a photo CVD method, a plasma A photoconductive layer made of a-Si is formed by a film forming method such as a CVD method. Among them, a plasma CVD method, that is, a method in which a source gas is decomposed by high-frequency or microwave glow discharge to form an a-Si deposited film on a substrate has been put to practical use as a suitable method.
[0005]
For example, Japanese Unexamined Patent Publication No. 57-115556 discloses that a photoconductive member having a photoconductive layer composed of an a-Si deposited film has electrical, optical, and darkness values, photosensitivity, and photoresponsiveness. In order to improve the use environment characteristics such as photoconductive characteristics and moisture resistance, and the stability over time, a non-conductive layer containing silicon atoms and carbon atoms is formed on a photoconductive layer composed of an amorphous material containing silicon atoms as a base material. A technique for providing a surface barrier layer made of a photoconductive amorphous material is described. Further, Japanese Patent Application Laid-Open No. Sho 60-67951 describes a technique relating to a photoconductor in which a light-transmitting insulating overcoat layer containing a-Si, carbon, oxygen and fluorine is laminated. Japanese Patent No. 168161 describes a technique using an amorphous material containing silicon atoms, carbon atoms, and 41 to 70 atomic% of hydrogen atoms as constituent elements as a surface layer.
[0006]
Japanese Patent Application Laid-Open No. 62-028764 discloses a photosensitive member comprising a charge blocking layer, a photoconductive layer, an intermediate layer, and a surface-modified layer. A photoconductor having an intermediate layer made of amorphous hydrogenated and / or fluorinated silicon containing at least one of atoms, nitrogen atoms and oxygen atoms is disclosed. Japanese Patent No. 2,566,762 discloses a negative injection layer in which a carrier injection blocking layer made of group 15 atom-containing a-Si, a carrier transport layer made of a-Si, a carrier generation layer made of a-SiC, and a surface layer are sequentially stacked. A technique for obtaining an electrophotographic photosensitive member for charging has been disclosed.
[0007]
These techniques have improved the electrical, optical, photoconductive properties and use environment properties of the electrophotographic photoreceptor, and accordingly the image quality.
[0008]
The method of charging the a-Si photoreceptor includes a corona charging method using corona charging, a roller charging method in which charging is performed by direct discharge using a conductive roller, a sufficient contact area with magnetic particles, etc., and the charge is exposed to light. There is an injection charging method in which charging is performed by directly injecting into the body surface. Among them, the corona charging method and the roller charging method use discharge, so that discharge products easily adhere to the surface of the photoreceptor. In addition, since the a-Si photoreceptor has a surface layer that is much harder than organic photoreceptors, discharge products tend to remain on the surface, and discharge is generated by adsorption of moisture in a high humidity environment. An object and moisture combine to lower the resistance of the surface, and the charge on the surface is likely to move, which may cause an image deletion phenomenon. Therefore, various measures such as a method of rubbing the surface and a method of controlling the temperature of the photoreceptor may be required.
[0009]
On the other hand, since the injection charging method is a charging method in which electric charge is directly injected from a portion in contact with the surface of the photoreceptor without actively using discharge, a phenomenon such as image deletion occurs. Hateful.
[0010]
In addition, the injection charging method, which is contact charging, has a merit that unevenness of charging potential is relatively easily reduced because the corona charging method is a current control type, but is a voltage control type.
[0011]
[Problems to be solved by the invention]
Conventional a-Si electrophotographic photoreceptors have electrical, optical and photoconductive properties such as dark resistance, photosensitivity, and photoresponsiveness, and use environment properties, and furthermore, stability with time and durability. In this respect, although the characteristics are individually improved, there is still room for further improvement in the overall improvement of the characteristics.
[0012]
In particular, in recent years, the shift to digitalization and colorization has rapidly progressed, and the demand for higher image quality of electrophotographic apparatuses has been increasing more than before. In addition, demands for higher speed and higher durability are also rapidly increasing, and in electrophotographic photoreceptors, with further improvement of electrical and photoconductive properties, charging performance and sensitivity are maintained in all environments. Significant performance enhancement is required.
[0013]
For example, as the most common combination of charging and developing in a full-color copying machine, a negative toner having a wide range of material selection as a color toner, an image exposure which has high controllability of a latent image and is easy to provide high image quality (a method of exposing an image portion) In this case, it is necessary to charge the photosensitive member with a negative charge. When an electrophotographic photosensitive member composed of an a-Si-based material is used as an electrophotographic photosensitive member for negative charging, electrons having a higher mobility than holes can be used as main carriers, so that photosensitivity is increased. It is considered that there are great advantages in that high performance can be expected, and there is a possibility that a similar process can be easily applied to an electrophotographic process for an organic photoreceptor in which negative charging is common. On the other hand, compared to the case of using positive charging, it is expected that the injection of charges from the surface layer side is relatively easy to occur, and it is difficult to obtain a charging ability. Therefore, it is desirable to provide an upper blocking layer to block the injection of electrons from the surface as much as possible, and how to improve the upper blocking layer is the key to improving the characteristics.
[0014]
In particular, as the speed and size of electrophotographic devices have been increased in recent years, the size of charging devices has been reduced, and the speed at which a copy has passed through a copying process (hereinafter referred to as process speed) has been increasing. In addition, the passage time of the photoreceptor in exposure to a latent image is shortened, and the demand for a photoreceptor having high charging ability and high sensitivity is increasing, and the importance of an upper blocking layer is increasing more and more. Therefore, this upper blocking layer has a great effect on the photoreceptor characteristics and must be carefully prepared.
[0015]
In addition, as described above, the injection charging method having various merits, for example, in the injection charging method using a magnetic brush, the polishing of the surface of the photoreceptor by the charging member easily proceeds, and the method of forming the surface layer is carefully selected. If not, there is a possibility that adverse effects such as an increase in the shaving amount of the surface layer and an unevenness in sensitivity due to shaving unevenness may occur, and thus care must be taken.
[0016]
In addition, in a full-color copying machine, a copying process with extremely small uneven charging is required. However, the above-described device for forming the upper blocking layer suppresses uneven charging ability of the photoreceptor, and is the above-described voltage control type. At present, even with the use of the injection charging system, further suppression of charging unevenness is desired.
[0017]
In addition, demands for optical memories are increasing for higher image quality. In order to suppress the optical memory due to the image exposure, a method of eliminating the optical memory by setting a static elimination light source in front of the charger and generating a large amount of carriers using relatively strong exposure is usually adopted. However, since the carrier due to the static elimination light consumes the charged charge, for example, in the case of a current control type such as corona charging, when the amount of the static elimination light is increased to erase the optical memory, the charging ability decreases. I will. Therefore, in general, there is a close trade-off between the optical memory and the charging ability.
[0018]
Further, even in the case of the contact charging of the voltage control type, if the charging time is shortened, the amount of the applied charge may be limited, and the charging ability may be reduced in accordance with the amount of the discharging light. In recent years, there has been a strong demand for a higher speed, and it is currently difficult to further improve the charging ability by the higher speed. Therefore, a copying process capable of achieving a high charging ability while reducing the optical memory has been desired.
[0019]
[Means for Solving the Problems]
The present inventors have solved the above-mentioned problems, and are a high-quality, high-durability, high-speed copying process.There is no charging unevenness or ghost, unevenness in sensitivity due to shaving unevenness hardly occurs, and high charging ability and high contrast. As a result of intensive studies to realize the copying process, the above object was improved by arranging a plurality of contact charging means and optimizing the conditions for forming the photoreceptor, especially the conditions for forming the upper blocking layer and the surface layer. And found that the present invention was achieved.
[0020]
That is, the electrophotographic apparatus of the present invention is an electrophotographic apparatus including each unit of static elimination, charging, latent image exposure, development, and transfer,
The charging unit is a contact charging unit, and a plurality of the charging units are arranged along a moving direction of the photoconductor.
A photoconductive layer made of a non-single-crystal material containing silicon as a host and containing at least a hydrogen atom and / or a halogen atom;
An upper blocking layer made of a non-single-crystal material containing silicon and carbon as base materials and containing a group 13 atom of the periodic table;
A surface layer made of a non-single-crystal material having at least carbon as a component, and the surface layer has a dynamic hardness of 4900 to 12750 N / mm. ² (500-1300kgf / mm ² )
It is characterized by.
[0021]
In addition, it is preferable that the plurality of charging units include a conductive roller charger on the upstream side in the moving direction of the photoconductor and a magnetic brush charger on the downstream side.
[0022]
In addition, in the charging means having the above-described configuration, the time S (s) from when the surface of the photoreceptor passes directly below the charger on the upstream side to when the surface of the photoreceptor reaches directly below the charger on the downstream side, and The relationship t / S (μm / s) with the thickness t (μm) is more preferably 10 or less.
[0023]
In addition, the development is preferably reversal development.
[0024]
In addition, in the upper blocking layer, the range of the ratio C / (Si + C) of carbon atoms to the sum of silicon atoms (Si) and carbon atoms (C) is 0.05 ≦ C / (Si + C) ≦ 0.6. Preferably, there is.
[0025]
In addition, in the upper blocking layer, the content of Group 13 atoms in the periodic table with respect to the sum of silicon atoms and carbon atoms is preferably 100 atomic ppm or more and 30000 atomic ppm or less.
[0026]
In addition, the thickness of the upper blocking layer is preferably 0.01 μm or more and 1 μm or less.
[0027]
In addition, it is preferable that the upper blocking layer contains hydrogen atoms, and the concentration of hydrogen atoms in the film thickness direction gradually decreases toward the surface layer.
[0028]
Further, it is preferable that a composition transition region in which the composition of silicon atoms and carbon atoms continuously changes in the film thickness direction at a value between the two layers is provided between the surface layer and the upper blocking layer.
[0029]
In addition, the surface layer may include at least silicon and hydrogen. In this case, the ratio C / (Si + C) of carbon atoms to the sum of silicon atoms (Si) and carbon atoms (C) is preferably set to 0.7 or more.
[0030]
Further, the surface layer may be made of an amorphous carbon film containing at least hydrogen.
[0031]
(Action)
The present inventors have combined various electrophotographic processes and various photoconductor manufacturing conditions in order to realize higher image quality and higher durability in the combination of the injection charging method and the negative charging a-Si photoconductor. , Studied diligently.
[0032]
As a result, in the electrophotographic process, the charging member is placed in multi-stage contact charging before the charging, and the photosensitive member prevents charge injection from above and does not prevent passage of necessary charges. By combining the improvement of the upper blocking layer and the improvement of the surface layer with high hardness which can hardly be scraped by rubbing with a magnetic brush etc., it is possible to achieve both high charging performance and extremely small potential unevenness. It has been found that image defects, sensitivity unevenness, optical memory, and the like due to a decrease in surface resistance can be suppressed at the same time, and it is possible to achieve both high image quality and high durability in a high degree.
[0033]
As described above, when the a-Si photoreceptor for negative charging is used, the main carrier can be an electron, so that the carrier mobility can be increased. Photosensitivity shows a positive correlation with this carrier mobility, while optical memory shows a negative correlation. Generally, the lower the optical memory, the better in the electrophotographic process. Therefore, there is a possibility that high sensitivity and reduction of optical memory can be achieved, and high performance can be expected. However, as disadvantages, it is difficult to prevent charge injection from the surface side, it is difficult to make the charging voltage higher than positive charging, dark decay is bad, and the charging polarity is negative, so it is susceptible to ozone It has been pointed out that the image deletion characteristic is apt to deteriorate.
[0034]
Therefore, in order to improve these, improvement of the upper blocking layer and improvement of the charging method have been individually performed. In other words, by improving the upper blocking layer, charge injection from the upper portion has been suppressed, the running of photogenerated carriers has been smoothed, etc., and the charging ability, the dark decay has been reduced, and the optical memory has been suppressed. In addition, by using contact charging, particularly injection charging, potential unevenness has been suppressed and resistance reduction due to ozone products on the surface has been suppressed.
[0035]
However, as described above, the demand for higher image quality in full-color processes and the like has increased in recent years, and further improvements in electrophotographic characteristics, such as further improvement in chargeability, further reduction in chargeability unevenness, and reduction in optical memory, have been made. Is needed.
[0036]
Therefore, the present inventors have paid attention to the behavior of the carrier due to the charge removal light. In the a-Si photoreceptor, charge erasing light is often used to erase the optical memory, and unevenness of the carrier due to the charge elimination light and uneven discharge of the carrier (the carrier moves in the film due to the electric field generated in the film by the charged charges). Unevenness) may affect charging unevenness. In order to suppress this phenomenon, it is conceivable to provide a charger for sufficiently discharging the carrier generated by the neutralization light before the main charging, but it is not always possible to provide a level capable of responding to recent high level demands. There have been cases where this has not happened. In other words, there is a limit only to the contrivance by the charger, and comprehensive improvement including the photoreceptor has become indispensable.
[0037]
Therefore, the present inventors focused on the characteristics of the upper blocking layer, and formed the upper blocking layer from a non-single-crystal material containing silicon and carbon as base materials and containing an atom of Group 13 of the periodic table, so that a carrier film could be formed. It has been found that the running property of the carrier is improved, the carrier is efficiently discharged, and the charging unevenness is further reduced. As a result, an overall improvement of the charger and the photoconductor was realized. That is, by optimizing the composition of the upper blocking layer and combining the charger with a multi-stage configuration including a plurality of contact chargers, the discharger of the charge elimination photocarrier by the preceding charger can be extremely efficiently performed, and the charging performance can be improved. It has been found that unevenness is drastically reduced.
[0038]
However, if contact charging is provided in multiple stages in this way, the polishing power increases accordingly, and even if the a-Si photoreceptor is high in hardness, if abrasion occurs, durability is reduced, or if abrasion unevenness occurs, There is a possibility that sensitivity unevenness or cleaning failure may occur.
[0039]
Therefore, in the present invention, the surface layer is made of a non-single-crystal substance whose base material is carbon, and its dynamic hardness is 4900 to 12750 N / mm. ² (500-1300kgf / mm ² ) Achieves an exquisite balance between shaving, abrasion and cleaning. As a result, it was found that it was highly durable, did not cause shaving unevenness, etc., did not cause image deletion due to the adhesion of ozone products, and did not cause cleaning failure.
[0040]
As described above, the combination of the optimization of the material of the upper blocking layer, the optimization of the material and hardness of the surface layer, and the optimization of the charging method is the first copy process using the conventional a-Si photoconductor for negative charging. Have been found to be able to solve all of the problems described above, and it has been found that the potential of the above process can be maximized.
[0041]
In this case, a charging device having a conductive roller charger as a contact charger on the upstream side in the moving direction of the photoconductor and a magnetic brush charger on the downstream side has good charging characteristics and has an effect of suppressing uneven charging ability. And the balance between the polishing power and the image flow suppressing effect was extremely excellent, which proved to be more preferable. The reason is considered as follows.
[0042]
When using a magnetic brush charger, it is preferable to move the magnetic particle carrier in the counter direction with the photoreceptor from the viewpoint of chargeability, but when the rubbing of the photoreceptor by the magnetic particles is in the counter direction, The amount of wear on the photoreceptor surface is considerably large. If this is done in two stages, the amount of wear will be extremely large, which may be undesirable. However, when the rubbing force is reduced by reducing the coating amount of the magnetic particles, at the same time, the charging ability of the magnetic particle carrier itself decreases, and in some cases, the charging ability unevenness occurs, or the sweeping unevenness of the magnetic brush (on the image) (Sweeping brushes that appear). In particular, when charging ability unevenness occurs in the charging unit located most downstream in the moving direction of the photoconductor, it becomes difficult to uniformly charge the surface of the photoconductor, and this tends to affect an output image. Therefore, the coating amount of the magnetic brush charger on the downstream side cannot be reduced. Therefore, when the magnetic brush is also on the upstream side, the coating amount must be reduced, and the charging effect on the upstream side is reduced.
[0043]
It has been found that the above problem can be solved by using a conductive roller on the upstream side. That is, by using a conductive roller, it is easy to adjust so as to reduce the polishing force as compared with a magnetic brush charger, and by combining with a magnetic brush, it is easy to balance the polishing force and the charging characteristics. At this time, there is a concern that the ozone product adheres due to the discharge, but it can be removed by the polishing force of the magnetic brush charger on the downstream side, and the possibility of remaining on the surface is reduced. Further, there are many merits as compared with the case where the corona charger is used on the upstream side. In other words, the conductive roller itself has an abrasive power, and the amount of the generated ozone product is advantageously smaller than that of corona charging. Also, when discharging the charge removing optical carrier, the discharge unevenness can be reduced as compared with the constant current type corona charging.
[0044]
For this reason, when the plurality of charging units are a two-stage charging unit combining a conductive roller charger on the upstream side in the movement direction and a magnetic brush charger on the downstream side, the effects of the present invention can be more suitably obtained. .
[0045]
Further, when there is a certain relationship between the time interval of the two-stage charging means and the thickness of the upper blocking layer of the photoreceptor, the effects of the present invention can be more suitably obtained, which is preferable. It turns out. Specifically, the time S (s) from the time when the surface of the photoreceptor passes just below the charger on the upstream side to the time immediately below the charger on the downstream side, and the thickness t (μm) of the upper blocking layer Is more preferably 10 or less (t / S (μm / s)). The reason for this is not completely known, but is considered as follows.
[0046]
In a copying process using an a-Si photosensitive member, static elimination light is often used to cancel an optical memory. When the photoconductor reaches directly below the light source, a large amount of carriers are generated in the photoconductor, but the carriers do not drift (move by an electric field) because there is almost no charge on the surface. Next, the photoreceptor reaches just below the charger in the preceding stage. At this time, the surface is charged, and the charge removing optical carrier starts to drift. At this time, the carrier drift velocity seems to have a statistical distribution such as a Boltzmann distribution.
[0047]
In the case of a negatively charged photoreceptor, among carriers generated in the photoconductive layer, carriers that drift to the surface side are holes, and have a lower mobility than electrons, so that they are less likely to drift. It is important how to drift smoothly. Therefore, if the thickness of the upper blocking layer is extremely large, all the carriers, that is, most of the carriers having the statistical distribution, including the tail portion, do not cancel out the electric charge on the surface, and thus the downstream side is formed. In some cases, charging is started by the charging device of (1). In such a case, it is considered that carrier discharge unevenness generated by the charge removal light remains. Therefore, it is preferable that the film thickness is somewhat thin. Similarly, considering the flow of the carrier, if the time interval between the two chargers is short, the discharge unevenness of the carrier may remain. From the above, it can be seen that the larger the film thickness, the shorter the distance between the chargers, and the faster the process speed, the lower the probability that all the charge removal photocarriers have drifted, which is disadvantageous for unevenness.
[0048]
That is, in the form of t / S (μm / s), which is proportional to the thickness t (μm) of the upper blocking layer and inversely proportional to the time S (s) for passing through the two chargers, It is possible to calculate a limit (such as a minimum speed required in the tail portion of the drift speed distribution) such as a limit at which the charge removing optical carrier ends drifting. That is, if the drift speed of the actual carrier, including the tail portion of the distribution, is higher than the value of t / S determined by the copying process or the layer configuration of the photoreceptor, all of the charge removing photocarriers are on the surface. After the cancellation of the charge, the charging on the downstream side is started, and it is considered that the effect of suppressing the uneven charging is obtained to the maximum.
[0049]
As a result of the experiment, if the combination of the position of the charger, the process speed, and the film thickness of the upper blocking layer is set so that the above-mentioned t / S (μm / s) becomes 10 or less, the discharge unevenness of the charge removing light carrier is reduced. It was found that there was almost no unevenness in charging ability, which is considered to be caused, and extremely uniform charging was obtained. This value is a large (slow) value when considered from the original mobility (average value) of holes in the upper blocking layer, but is actually affected by the interface between the photoconductive layer and the upper blocking layer. It is considered that it was difficult to derive from the theoretical value because of the influence of the carrier generation distribution and the mobility distribution, and it was determined only experimentally. In addition, it was found that the carrier flow did not depend much on the intensity of the charge removing light and the charging conditions. Therefore, if the static elimination light intensity and the charging conditions are within the normal range, the suppression of the carrier discharge unevenness largely depends only on the value of t / S described above. Is more preferably obtained.
[0050]
Further, it has been found that the effects of the present invention can be more suitably obtained by using reversal development in the present invention. In the reversal development, an area exposed to light is developed, and therefore, an image exposure method (hereinafter, referred to as IAE) for exposing an image portion is used. Conversely, a method of exposing a non-image portion (background portion) is called a background exposure method (hereinafter, referred to as BAE), and in this case, normal development is used.
[0051]
BEST MODE FOR CARRYING OUT THE INVENTION
Regarding the reduction of unevenness as an object of the present invention, it is most important to reduce unevenness in a low-density portion where density unevenness is most conspicuous, particularly when considering high image quality such as a full-color image. Therefore, in the present invention, a configuration was found in which unevenness of charging ability (particularly unevenness in the circumferential direction) was suppressed to the utmost. At this time, when a combination of BAE and normal development is used, the low-density portion is a portion where the potential is lowered by exposure, and this value is greatly affected by the sensitivity. Of course, if the charging potential Vd is made uniform, it can be expected that the uniformity of the exposed portion potential will also be improved. However, the unevenness of the low-density portion is more likely to be caused by the sensitivity unevenness of the photoconductor than by the charging ability unevenness. It has a significant effect.
[0052]
On the other hand, in the case of the combination of IAE and reversal development, the low-density portion is a portion close to the charging potential Vd, and if the unevenness of the charging potential Vd can be minimized, the unevenness of the low-density portion can be reduced. That is, in the electrophotographic system including the charging system and the photoreceptor, which is a constitution of the present invention, it is most preferable to use a combination of IAE and reversal development. This is more preferable because the latitude can be widened and unevenness in the low-density portion where the unevenness in density is most conspicuous can be suppressed at a high level, and the effect of the present invention can be more expected.
[0053]
In the upper blocking layer of the present invention, the composition ratio of silicon atoms to carbon atoms as a base is appropriately determined, and then the content of Group 13 atoms in the periodic table that functions as a dopant is appropriately added. Thus, further improvement in electrophotographic characteristics such as further improvement of charging ability by suppression of stopping power, suppression of unevenness of charging ability, and reduction of optical memory can be expected, which is more preferable.
[0054]
Specifically, it is desirable that the range of the ratio C / (Si + C) of carbon atoms to the sum of silicon atoms and carbon atoms be 0.05 ≦ C / (Si + C) ≦ 0.6. By forming a film in this range, a film having a high stopping power and good other electrophotographic characteristics can be obtained. If the carbon content is higher than this, the residual potential will increase, and the controllability of the conduction type will decrease. Further, if the carbon content is further reduced, the dark resistance is reduced and the stopping power may be reduced. It is more preferably 0.1 or more and 0.5 or less, and most preferably 0.15 or more and 0.4 or less.
[0055]
The specific content of Group 13 atoms is appropriately determined as desired so that the object of the present invention can be effectively achieved. Preferably, the concentration in the film is 100 atoms per silicon atom. What is necessary is just to introduce so that it may become more than 30000 atomic ppm below ppm. If it is less than 100 atomic ppm, sufficient stopping power for electrons may not be obtained in some cases. From such a viewpoint, 500 atomic ppm or more is more preferable. On the other hand, if it exceeds 30,000 atomic ppm, the effect of improving the charging ability unevenness may be reduced. In order to maximize the improvement effect, it is more preferably 10,000 atomic ppm or less.
[0056]
Further, regarding the thickness of the upper blocking layer, there is an optimum condition other than the above-described temporal relationship between the chargers. Specifically, if the thickness is not more than 0.01 μm, the improvement of the stopping power cannot be expected, while if it is less than 1 μm, it may be difficult to suppress the residual potential. Therefore, the thickness is preferably from 0.01 μm to 1 μm, more preferably from 0.02 μm to 0.5 μm, and most preferably from 0.05 μm to 0.3 μm.
[0057]
Further, it is preferable that the upper blocking layer contains hydrogen atoms, and the content is distributed such that the content is reduced on the surface side. By doing so, the adhesion of the film can be improved, which is more preferable. This mechanism is considered as follows.
[0058]
The upper blocking layer is based on silicon and carbon and contains a large amount of Group 13 atoms, for example, boron atoms, for controlling its valence electrons. When a large amount of boron atoms is contained, peeling may easily occur. This is thought to be due to the fact that boron is a three-coordinate atom, which distorts the bond, but the details are unknown. When a large amount of boron is mixed in this way, the phenomenon that the upper blocking layer and the surface layer are peeled off from the photoreceptor and the peeled film looks like gold powder is very rare, but depending on the forming conditions, Occurred.
[0059]
Therefore, the present inventors have found that this stress can be relaxed by gradually decreasing the concentration of hydrogen atoms contained in the film toward the surface. Hydrogen is considered as a terminal atom of the bond, and the hydrogen relaxes the bond distortion caused by the incorporation of a large amount of three-coordinate boron, and the degree of the relaxation depends on the combination of the stress with the photoconductive layer and the surface layer. It is thought that they function effectively in combination, but exact stress measurement and analysis of the bonding method are difficult and the details are unknown.
[0060]
As described above, by forming the film so that the concentration of hydrogen atoms in the film gradually decreases toward the surface side, stress can be relaxed and peeling can be completely eliminated, which is more preferable.
[0061]
Specifically, in order to gradually reduce the concentration of hydrogen atoms to the surface side as in the present invention, the heating temperature of the substrate may be gradually increased when forming the upper blocking layer. However, it is not preferable to raise the temperature suddenly, since a strain is introduced on the contrary to cause a crack. Although depending on the composition ratio of silicon and carbon, if C / (Si + C) is about 0.15 to 0.4, the temperature difference between the start and end of the upper blocking layer is about 5 to 30 ° C., and the temperature change Is preferably about 3 ° C./min or less.
[0062]
Similarly, for the purpose of relaxing the stress, a composition transition region that continuously changes the composition of silicon and carbon may be provided. In this case, the concentration of Group 13 atoms in the periodic table may be constant, but it is more preferable to increase the concentration from the base toward the surface. That is, when silicon is large, valence electron control can be performed even if the amount of group 13 atoms is small, but when carbon is large, the concentration of group 13 atoms must be increased. What is necessary is just to determine in consideration of stress.
[0063]
The surface layer of the present invention is made of a non-single crystal material containing carbon as a base material, and thus has high hardness and good slipperiness, is inert, hardly undergoes chemical changes such as oxidation, and has multiple contact charging. This is very important in realizing the electrophotographic apparatus of the present invention using the image. The term “non-single-crystal substance” as used herein refers to a substance mainly composed of an amorphous material, but may partially include a microcrystal, a polycrystal, or the like.
[0064]
The surface layer may contain at least silicon and hydrogen, and in this case, the range of the ratio of carbon atoms to the sum of silicon atoms (Si) and carbon atoms (C), C / (Si + C), is appropriately adjusted. It is preferable to set. Specifically, it is preferable that the ratio C / (Si + C) between silicon atoms and carbon atoms be in a range of 0.7 or more. By setting the content in this range, the hardness, the slipperiness, and the chemical stability described above are improved, and by setting the content to 0.7 or more, the resistance value of the surface layer can be set in an appropriate range. As a result, it is possible to prevent, for example, an increase in the residual potential due to the retention of carriers in the photoconductor due to an increase in resistance, which is favorable.
[0065]
Further, the surface layer may be formed of a non-single-crystal carbon film containing at least hydrogen. By using a non-single-crystal carbon film, higher hardness can be realized as compared with amorphous silicon carbide. In addition, the non-single-crystal carbon film itself has a very small surface free energy, and therefore grows in a direction in which the unevenness of the underlayer is reduced when growing on the underlayer, so that the outermost surface becomes smooth. Therefore, cleaning controllability can be improved, which is good. In addition, the fact that the surface free energy is low means that the substance does not easily adhere, and there is also an advantage that the ozone product does not easily adhere and the image deletion hardly occurs.
[0066]
With the improvements described above, the present invention achieves a high level of compatibility between the multi-stage contact charging, the improvement of the charging ability by the improvement of the electrophotographic photosensitive member, and the suppression of the charging unevenness, and the image quality is dramatically improved, and the longevity is improved. Provided is an electrophotographic apparatus capable of simultaneously achieving a dramatic reduction in maintenance frequency by a photoconductor. In addition, the image quality has been dramatically improved by reducing the optical memory and preventing image deletion, solving all of the above-mentioned problems in the prior art, and providing an electronic device having extremely excellent image quality, durability and environmental resistance. Provide a photographic device.
[0067]
Hereinafter, the electrophotographic apparatus of the present invention will be described in detail with reference to the drawings.
[0068]
FIG. 1 is a schematic view showing an example of an image forming process of an electrophotographic apparatus, in which a photoreceptor 101 rotates to perform a copying operation clockwise in the direction of an arrow. Around the photosensitive member 101, a conductive roller charger 102, a magnetic brush charger 103 of an injection charging system, a developing device 104, a transfer paper supply system 105, a transfer charger 106 (a), and a separation charger 106 (b). , A cleaning unit 107, a transport system 108, a static elimination light source 109, and the like.
[0069]
Hereinafter, the image forming process will be described more specifically. The photoconductor 101 is precharged by a roller charger 102 and then uniformly charged by a magnetic brush charger 103 as a main charger. Next, an electrostatic latent image is formed by light emitted from the laser unit 118 and passed through the mirror 119, and a negative polarity toner is supplied from the developing device 104 to the latent image to form a toner image. The signal from the CCD unit 117 is used for controlling the laser unit 118. That is, the light emitted from the lamp 110 is reflected on the original 112 placed on the original platen glass 111, passes through mirrors 113, 114, 115, forms an image by the lens of the lens unit 116, and generates an electric signal by the CCD unit 117. Is converted into a signal.
[0070]
On the other hand, the leading end timing is adjusted by the registration roller 122 through the transfer paper supply system 105, and the transfer material M supplied in the direction of the photoconductor 101 is transferred between the transfer charger 106 (a) to which a high voltage is applied and the photoconductor 101. In the gap, a positive electric field having a polarity opposite to that of the toner is applied from the back surface, whereby the negative polarity toner image on the photosensitive member surface is transferred to the transfer material M. Next, the transfer material M reaches the fixing device 124 through the transfer conveyance system 108 by the separation charger 106 (b) to which the high-voltage AC voltage is applied, where the toner image is fixed and is carried out of the device.
[0071]
The toner remaining on the photoreceptor 101 is collected by the cleaning blade 121 of the cleaning unit 107, and the remaining electrostatic latent image is erased by the charge eliminating light source 109.
[0072]
FIG. 2 is an explanatory diagram schematically showing a charging process portion of the image forming apparatus suitably used in the present invention. In FIG. 2, a conductive roller (charging device) 202 is used as a charging device on the upstream side in the rotation direction, and a magnetic brush charging device 203 of an injection charging system is used as a charging device on the downstream side with respect to the a-Si photosensitive drum 201. Was.
[0073]
A magnetic brush charger is a device in which conductive magnetic particles are directly magnetically constrained on a magnet or a sleeve enclosing the magnet, stopped or rotated, and brought into contact with a photoreceptor, and a voltage is applied thereto. Charging is started. The magnetic brush charger 203 suitably used in the present invention has a fixed magnet 204 provided therein, and is provided on a rotatable non-magnetic charging sleeve 205 for charging regulated by magnetic particle regulating means (blades) 207. The magnetic particles 206 are formed into a brush shape by a magnetic field, and the charging magnetic particles 206 are transported as the non-magnetic sleeve 205 rotates. By applying a charging voltage to the charging sleeve 205, charges are given from the charging magnetic particles 206 onto the photosensitive drum 201, and charged to a value close to a potential corresponding to the charging voltage.
[0074]
The charging sleeve 205 can be rotated in the forward direction or the counter direction with respect to the photoconductor 201, and the relative speed with respect to the photoconductor 201 can be set as desired. It is determined by comprehensively considering various characteristics such as the set life of the photoconductor, the set life of the magnetic particles, the charging ability, and the presence or absence of sweeping unevenness. Specifically, when the surface layer having the hardness of the present invention is used, which is made of the non-single-crystal material based on carbon of the present invention and has a hardness of the present invention, for example, the rotation speed of the photoconductor 201 is 300 mm / s and the magnetic brush charger 203 is used. When the was rotated at 360 mm / s in the counter direction, it was confirmed that the above-mentioned various properties were good.
[0075]
The magnetic brush charger 203 can reduce the amount of coating of the magnetic particles by reducing the distance between the magnetic particle regulating means (blade) 207 and the sleeve 205, thereby reducing the rubbing force and extending the life of the photoconductor. On the other hand, at the same time, the contact point between the magnetic particles and the photoreceptor decreases, so that the charging ability of the charger also decreases. In the present invention, the charging means has a multi-stage structure, and the charging ability can be supplemented to some extent.
[0076]
The magnetic particles for charging have an average particle size of 10 to 100 μm and a saturation magnetization of 2.5 × 10 ^-2 ~ 3.1 × 10 ^-1 Wb / m ² (20-250 emu / cm ³ ), Resistivity is 10 ² -10 ¹⁰ Ω · cm is preferred. In order to improve the charging performance, it is better to use a material having the lowest possible resistivity. ⁶ It is more preferable to use one having Ω · cm or more.
[0077]
For example, the magnetic particles for charging may be oxidized or reduced on the ferrite surface to adjust the resistance. The average particle diameter is 25 μm, and the saturation magnetization is 2.5 × 10 5. ^-1 Wb / m ² (200 emu / cm ³ ), Resistivity is 5 × 10 ⁶ Ω · cm is suitably used. The charging magnetic particles 206 used in this example have a resistance value of 228 mm in bottom area. ³ 650 kPa (6.6 kgf / cm) ² ), And measured by applying a voltage of 100V.
[0078]
The charging roller 202 includes a conductive core 208, an elastic layer 209, and a surface layer 210. As the core bar 208, iron, aluminum, stainless steel, or the like can be preferably used. The elastic layer 209 is made of a solid or foamed solid elastic material such as urethane, silicone rubber, EPDM (terpolymer of ethylene propylene diene), and carbon or TiO. ₂ A metal oxide such as ZnO or the like and having a volume resistivity of 1E4 to 1E13 Ω · cm can be suitably used.
[0079]
The surface layer 210 is preferably made of a nylon resin such as resin (trade name) or a synthetic resin film made of polyethylene, polyester, fluororesin, polypropylene, or the like. It is desirable that the resistance value is larger than the resistance of the inner elastic body. Thus, even if there is a pinhole on the surface of the electrophotographic photosensitive member, it is more preferable that current concentrates and does not easily flow. Specifically, for example, a charging roller in which a surface layer of a synthetic resin film in which a nylon-based resin is made conductive is provided on an elastic layer in which resistance is adjusted by dispersing carbon in urethane is preferably used. The charging roller 202 is driven by the photoconductor 201 to perform charging.
[0080]
FIG. 3 shows an example of an electrophotographic apparatus for forming a color image. In this color image forming apparatus, first to fourth four image forming units Pa to Pd capable of forming visible images (toner images) of, for example, yellow, magenta, cyan, and black in a main body of the apparatus are straight lines. The image forming units Pa to Pd include dedicated photoconductors 1a, 1b, 1c, and 1d, respectively. Each of the photoconductors 1a to 1d is driven to rotate in the direction of the arrow shown in the figure, and around them, chargers 2a to 2d, image exposure devices 3a to 3d, developing devices 4a to 4d, and a cleaner 5a, which are dedicated image forming process means. To 5d are provided.
[0081]
An intermediate transfer member 8 is stretched between a plurality of rollers below the photoconductors 1a to 1d of each of the image forming units Pa to Pd, and transfer units 6a to 6d are provided inside the intermediate transfer member 8 respectively. ing. As the intermediate transfer member 8 moves, images are sequentially formed in the transfer areas of the image forming portions Pa to Pd.
[0082]
Further, a transfer belt 9 is stretched between rollers below the intermediate transfer body 8, and a transfer charging unit 10 is provided inside the transfer belt.
[0083]
In FIG. 3, a paper feed unit is disposed on the right side of the transfer belt 9, and a fixing unit 7 is disposed on the left side. Further, a pair of registration rollers 13 for feeding the recording material M at a timing is arranged between the paper supply unit and the transfer belt 8, and the recording material M is supplied from the paper supply unit to the registration rollers 13. After the multiplex image of four colors formed on the intermediate transfer member 8 is transferred to the recording material M at the transfer charging unit 10, the recording material M The image moves and passes through the fixing device 7 to fix the image.
[0084]
More specifically, in the first image forming unit (here, Pd), the image information of the yellow component color in the original image is scanned on the photosensitive member 1d charged by the charger 2d by using a laser beam or the like, and the yellow component is scanned. A colored electrostatic latent image is formed. This electrostatic latent image is developed with a yellow toner by the developing device 3d to become a yellow visible image.
[0085]
On the other hand, the intermediate transfer member is moving during that time, and a yellow visible image formed on the photosensitive member 1d by the action of the transfer charging means 6d in the lower transfer region of the photosensitive member 1d of the first image forming portion Pd; That is, the toner image is transferred to the intermediate transfer member. While the yellow toner image is being transferred onto the intermediate transfer body 8 in this manner, an electrostatic latent image of a magenta component color is formed in the second image forming portion Pc, and this electrostatic latent image is developed by the developing device 3c. When the intermediate transfer member 8 is conveyed to the lower transfer area of the photoconductor 1c of the second image forming portion Pc, the magenta toner image moves to the transfer area, and the operation of the transfer charger 6c is performed. As a result, the image is transferred in a state of being superimposed on the yellow toner image on the intermediate transfer member 8.
[0086]
Hereinafter, cyan and black toner images are sequentially formed on the third and fourth image forming units Pb and Pa, similarly to the first and second image forming units Pd and Pc. Is transferred to the recording material M further moved on the transfer belt 9 to transfer a color image in which four colors are multiplex-transferred.
[0087]
When the image forming process is completed, the recording material M is separated from the transfer belt 9 and sent to the fixing device 7, where the recording material M is collectively fixed to obtain a desired full-color image. In addition, the residual toner is removed from the photoconductors 1a to 1d of the image forming units Pa to Pd after the transfer is completed by the cleaners 5a to 5d, so that the next electrostatic latent image is formed.
[0088]
FIG. 4 is a schematic configuration diagram for explaining an example of a preferred layer configuration of the electrophotographic photosensitive member produced by the production method of the present invention.
[0089]
4A, a lower blocking layer 402, a photoconductive layer 403 containing silicon as a base, an upper blocking layer 404 containing silicon and carbon as a base, and a carbon as a base on a substrate 401. A surface layer 405 made of a non-single crystal material is provided in this order.
[0090]
The upper blocking layer 404 is not necessarily required to have photoconductivity. On the other hand, a function that cannot be realized by the photoconductive layer 403 is required. It goes without saying that a distinctly different approach is taken. On the other hand, when compared with the surface layer 405, the required hardness, durability against ozone, and the like are not always required. On the other hand, a function that cannot be realized by the surface layer 405 is required. It is needless to say that a manufacturing method which is clearly different from that of the surface layer 405 is adopted in order to realize the above.
[0091]
FIG. 4B is a schematic configuration diagram for explaining another layer configuration. In the electrophotographic photoreceptor shown in FIG. 4A, the photoconductive layer 403 has a single-layer structure, whereas in FIG. 4B, the photoconductive layer is divided into two regions. For example, a high-quality film having high photocarrier generation efficiency and few defects is used in the upper region 407, and a film specialized in increasing the carrier mobility in the film is used in the lower region 406. It can be improved.
[0092]
In each of FIGS. 4A and 4B, the lower blocking layer 402 is not an essential component, and may be omitted as necessary. Also, the interface of each layer does not necessarily need to be a steep and clear interface, especially when using a laser exposure that easily causes light interference, so that the composition is smoothly changed at the interface so that a clear interface is not created. It is more desirable to do.
[0093]
<Base>
Examples of the substrate used in the present invention include metals such as Al, Cr, Mo, Au, In, Nb, Te, V, Ti, Pt, Pd, and Fe, and alloys thereof, and conductive substrates such as stainless steel. No. Further, a film or sheet of a synthetic resin such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polystyrene, polyamide, etc., at least the surface on the side on which the light-receiving layer is formed of an electrically insulating material such as glass, ceramic, etc. A conductive substrate subjected to a conductive treatment can also be used.
[0094]
The shape of the substrate 401 used in the present invention can be a cylindrical shape or an endless belt shape having a smooth surface or a fine uneven surface, and the thickness thereof can form a desired electrophotographic photosensitive member. As appropriate. When flexibility as an electrophotographic photosensitive member is required, it can be made as thin as possible as long as the function as the base 401 can be sufficiently exhibited. However, the substrate 401 is usually set to 10 μm or more in terms of production, handling, mechanical strength and the like.
[0095]
<Photoconductive layer>
In the present invention, the photoconductive layer 403 is formed by a vacuum deposition film forming method by appropriately setting numerical conditions of film forming parameters so as to obtain desired characteristics. Specifically, the glow discharge method is preferable because the conditions for manufacturing a photoreceptor having desired characteristics are relatively easy to control, and the high frequency glow discharge method using a power supply frequency in the VHF band is particularly preferable. It is suitable.
[0096]
In order to form the photoconductive layer 403 by the glow discharge method, basically, a silicon-containing gas capable of supplying silicon atoms (Si) is introduced in a desired gas state into a reaction vessel in which the pressure can be reduced. Glow discharge is generated in the reaction vessel, and a layer made of a-Si: H, X may be formed on a predetermined substrate 101 which is provided at a predetermined position in advance.
[0097]
In the present invention, a hydrogen atom (H) supply gas and / or a halogen atom (X) supply gas are introduced at the time of forming the photoconductive layer 403, so that hydrogen atoms and / or A halogen atom can be contained. This is more preferable because it compensates for dangling bonds of silicon atoms and can improve the layer quality, particularly the photoconductivity and the charge retention characteristics.
[0098]
The substance which can be a silicon-containing gas used in the present invention includes SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , Si ₄ H ₁₀ Silicon hydrides (silanes) in a gaseous state or in the form of a gas can be effectively used. In addition, SiH is preferable in terms of ease of handling during layer production, good Si supply efficiency, and the like. ₄ , Si ₂ H ₆ Are preferred.
[0099]
Then, for the purpose of introducing hydrogen atoms and halogen atoms into the formed photoconductive layer 403 structurally and facilitating control of the introduction ratio of these terminal atoms, these gases are further added with H. ₂ Alternatively, a desired amount such as a gas of a silicon compound containing a hydrogen atom, a halogen gas, a halide, an interhalogen compound containing a halogen, a gaseous or gasifiable halogen compound such as a silane derivative substituted with a halogen, or the like may be mixed. Good. In addition, each gas is not limited to a single species, and a plurality of species may be mixed at a predetermined mixture ratio.
[0100]
In order to control the amount of hydrogen atoms and / or halogen atoms contained in the photoconductive layer 403, for example, the temperature of the substrate 401, a reaction vessel of a raw material used to contain hydrogen atoms and / or halogen atoms What is necessary is just to control the amount introduced into the inside, the discharge power, and the like.
[0101]
In addition to these gases, a rare gas may be used as a diluent gas, or may be used alone or as a mixture with another diluent gas.
[0102]
In the present invention, atoms for controlling the conductivity can be introduced into the photoconductive layer 403 and may be further distributed.
[0103]
Examples of the atoms that control the conductivity include so-called impurities in the semiconductor field, and include atoms belonging to Group 13 of the periodic table that provide p-type conduction characteristics (hereinafter abbreviated as “Group 13 atoms”) or And / or an atom belonging to Group 15 of the periodic table that gives n-type conduction characteristics (hereinafter abbreviated as “Group 15 atom”) can be used.
[0104]
Specific examples of Group 13 atoms include boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl), with B, Al, and Ga being particularly preferred. .
[0105]
Specific examples of Group 15 atoms include nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), and lead (Pb), with P and As being particularly preferred.
[0106]
It is desirable that a material that can be a raw material for introducing a group 13 atom be a gaseous material at normal temperature and normal pressure or a material that can be easily gasified at least under layer forming conditions.
[0107]
For example, as a raw material for introducing a Group 13 atom, specifically, for introducing a boron atom, ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , B ₅ H ₁₁ , B ₆ H ₁₀ , B ₆ H ₁₂ , B ₆ H ₁₄ Borohydride, BF ₃ , BCl ₃ , BBr ₃ And the like. In addition, AlCl ₃ , GaCl ₃ , Ga (CH ₃ ) ₃ , InCl ₃ , TlCl ₃ And the like.
[0108]
Similarly, the raw material for introducing the group 15 atoms is preferably a gaseous substance or a substance which can be easily gasified.
[0109]
For example, as a raw material for introducing a Group 15 atom, specifically, for introducing a phosphorus atom, PH ₃ , P ₂ H ₄ Such as hydrogenated phosphorus, PF ₃ , PCl ₃ And the like. In addition, AsH ₃ , AsF ₃ , AsF ₅ , AsCl ₃ , SbH ₃ , SbF ₅ , BiH ₃ And the like.
[0110]
The content of the atoms for controlling the conductivity contained in the photoconductive layer 403 is adjusted by adding a trace amount of a gas containing these atoms to the source gas. Specifically, for example, B ₂ H ₆ When it is desired to add boron using a gas, B is added to facilitate the fine adjustment. ₂ H ₆ Gas to H ₂ It may be added after being diluted with He or the like. The specific content is preferably 5 × 10 ^-3 ５０50 atomic ppm, more preferably 1 × 10 ^-2 ~ 30 atomic ppm, optimally 5x10 ^-2 It is desirable that the maximum content and the minimum content are appropriately selected and contained within the range of ２０20 atomic ppm.
[0111]
Further, in the present invention, a carbon-containing gas, an oxygen-containing gas, and a nitrogen-containing gas may be appropriately added to the raw material gas so that the photoconductive layer 403 contains carbon atoms and / or oxygen atoms and / or nitrogen atoms. . The content of carbon atoms and / or oxygen atoms and / or nitrogen atoms is preferably 1 × 10 3 based on the sum of silicon atoms, carbon atoms, oxygen atoms and nitrogen atoms. ^-5 -10 atomic%, more preferably 1 × 10 ^-4 ~ 8 atomic%, optimally 1 × 10 ^-3 -5 atomic% is desirable. The carbon atoms and / or oxygen atoms and / or nitrogen atoms may be uniformly and uniformly contained in the photoconductive layer, or may have a non-uniform distribution such that the content changes in the thickness direction of the photoconductive layer. There may be a part.
[0112]
In the present invention, the layer thickness of the photoconductive layer 403 is appropriately determined as desired from the viewpoint of obtaining desired electrophotographic characteristics and economic effects, and is preferably 10 to 50 μm, more preferably 15 to 45 μm, Is preferably 20 to 40 μm. When the layer thickness is less than 10 μm, electrophotographic characteristics such as charging ability and sensitivity become practically insufficient, and when the layer thickness is more than 50 μm, the production time of the photoconductive layer becomes longer and the production cost becomes higher.
[0113]
In order to achieve the object of the present invention and to form the photoconductive layer 403 having desired film properties, the flow rate of the gas for supplying Si, the mixing ratio with the dilution gas when diluting, the gas pressure in the reaction vessel It is necessary to appropriately set the discharge power and the substrate temperature.
[0114]
Similarly, the optimum range of the gas pressure in the reaction vessel is appropriately selected according to the layer design. ^-2 ~ 1.0 × 10 ² Pa, preferably 5.0 × 10 ^-2 ~ 5.0 × 10Pa, optimally 1.0 × 10 ^-1 The pressure is preferably set to 2.0 × 10 Pa.
[0115]
Similarly, the optimum range of the discharge power is appropriately selected according to the layer design. The ratio P / F between the discharge power P (unit: W) and the flow rate F (unit: ml / min (normal)) of the silicon-containing gas is determined. It is desirably set in the range of 2 to 30, preferably 5 to 20, and most preferably 8 to 15.
[0116]
Further, the temperature of the base 401 is appropriately selected in an optimum range according to the layer design. In a normal case, the temperature is preferably 150 to 350 ° C, more preferably 170 to 330 ° C, and most preferably 190 to 310 ° C. Is desirable.
[0117]
In the present invention, the above-mentioned ranges are mentioned as desirable numerical ranges of the gas pressure for forming the photoconductive layer, the discharge power, and the substrate temperature. However, the conditions are not usually determined separately and independently. It is desirable to determine the optimum value based on mutual and organic relevance in order to form a photoreceptor having the following characteristics.
[0118]
<Upper blocking layer>
The upper blocking layer has a function of preventing charge from being injected from the free surface side to the photoconductive layer side when the photoreceptor is subjected to charging treatment on its free surface. In order to provide such a function, the upper blocking layer is required to have a high resistance of a certain level or more. To achieve this, the resistance is increased by adding some carbon to the a-Si film, and at the same time, the group 13 of the periodic table is formed. , It is necessary to set the resistance to holes in an appropriate range.
[0119]
The substance which can be a silicon-containing gas used in the present invention includes SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , Si ₄ H ₁₀ Isohydrogenated silicon (silanes), SiF ₄ Silane derivatives substituted with halogens, etc. can be used effectively. Further, the film properties can be improved, the handling is easy at the time of layer production, and the supply efficiency is high. ₄ Are the most preferred.
[0120]
As a substance that can serve as a carbon supply gas, CH ₄ , C ₂ H ₂ , C ₂ H ₆ , C ₃ H ₈ , C ₄ H ₁₀ Such a gas state or a gasifiable hydrocarbon is effectively used, and furthermore, the film properties can be improved, the layer can be easily handled at the time of layer formation, and it is difficult to polymerize. ₄ Is most preferred.
[0121]
Moreover, you may dilute using a suitable diluting gas as needed. As a specific diluent gas, a rare gas such as hydrogen, He, Ne, Ar, or Kr is appropriate, and a mixture of several types of these may be used.
[0122]
The composition of the upper blocking layer 404, that is, the range of the ratio C / (Si + C) of carbon atoms to the sum of silicon atoms and carbon atoms, should have a high stopping power and a favorable range for other electrophotographic characteristics. desirable. When carbon is added to the a-Si film, it is considered that the density of defect states tends to increase when light is applied. That is, the initial defect level density is N ₀ Where ΔN is the number of light-induced defects and ΔN / N ₀ Is the rate of increase in defect level density. This increase rate ΔN / N ₀ Believes that, based on experimental facts, the addition of a small amount of carbon causes a dramatic increase and then a decrease, but the precise measurement of ΔN is difficult and is not known at this time.
[0123]
It is considered that the range of the present application is preferable after the decrease is started, and the range in which valence electron control is possible is preferable. Specifically, it has been experimentally found that the range of 0.05 ≦ C / (Si + C) ≦ 0.6 is desirable. If the carbon content is higher than this, the valence electron controllability is reduced, and adverse effects such as an increase in the residual potential may appear. Further, if the carbon content is further reduced, it is considered that the rate of increase in the density of defect states may increase, or the dark resistance may decrease and the stopping power may decrease.
[0124]
In order to realize such a composition, when the above-mentioned gas is used as a raw material gas, its flow rate, mixing ratio, dilution rate, electric power per unit gas flow rate, and the like may be changed. However, since plasma CVD is generally sensitive to an apparatus, it is not always possible to determine exactly what composition can be obtained depending on the apparatus configuration or conditions, and a simple optical measurement (infrared absorption, visible light To measure the absorption coefficient of ultraviolet light), etc., and design the desired composition by changing the conditions while quantifying using secondary ion mass spectrometry (SIMS). It is desirable.
[0125]
In order to make the upper blocking layer contain atoms for controlling conductivity in the present invention, a gas containing Group 13 atoms as described above may be replaced with a silicon-containing gas, a carbon-containing gas, and / or a rare gas / hydrogen. It is realized by adding an appropriate amount to a source gas composed of a diluent gas such as the above. The specific content of Group 13 atoms is appropriately determined as desired so that the object of the present invention can be effectively achieved, but the concentration in the film is preferably 100 atomic ppm or more with respect to silicon atoms. What is necessary is just to introduce it so that it may be set to 30000 atomic ppm or less. If it is less than 100 atomic ppm, sufficient stopping power for electrons may not be obtained in some cases. From such a viewpoint, 500 atomic ppm or more is more preferable. On the other hand, if it exceeds 30,000 atomic ppm, the effect of improving the charging ability unevenness may be reduced. In order to maximize the improvement effect, the content is more preferably 10,000 atom ppm or less. Further, in order to increase the ease of adjusting the amount of addition, it may be appropriately added together with a diluent gas. Hydrogen gas or a rare gas is preferable as the diluent gas of the group 13 atom-containing gas.
[0126]
The atoms controlling the conductivity contained in the layer are uniformly distributed throughout the layer, so that a constant amount may be supplied at all times when the layer is formed, or the atoms may be distributed non-uniformly. The flow rate of the gas to be added may be changed with time. However, in any case, care should be taken to make the gas distribution uniform at the time of preparation so that the gas is contained in a uniform distribution in a direction parallel to the surface.
[0127]
In the present invention, the thickness of the upper blocking layer is preferably from 0.01 to 1.0 μm, more preferably from 0.03 to 0.7 μm, and most preferably from 0.05 to 0, since desired electrophotographic characteristics can be obtained. 0.5 μm is desirable. When the layer thickness is less than 0.01 μm, the ability to stop injection of electric charge from the surface becomes insufficient and sufficient charging ability cannot be obtained. When the layer thickness is more than 1.0 μm, the efficiency of discharging holes from the photoconductive layer is reduced. As a result, electrophotographic characteristics such as sensitivity, shift, ghost, and residual potential are deteriorated.
[0128]
In the present invention, to form the upper blocking layer, the same vacuum deposition method as the above-described method of forming the photoconductive layer, that is, a plasma CVD method using a high frequency is employed. At that time, in order to maximize the effect of the present invention, it is most preferable that the high frequency used for the discharge be a VHF band frequency. Further, in addition to the deposition conditions described above, it is necessary to appropriately set the pressure in the reaction vessel, the temperature of the substrate, and the like.
[0129]
An optimum range of the gas pressure in the reaction vessel is appropriately selected according to the layer design. ^-2 ~ 5.0 × 10 ² Pa, preferably 5.0 × 10 ^-1 ~ 5.0 × 10Pa, optimally 1.0 × 10 ^-1 The pressure is preferably set to 2.0 × 10 Pa.
[0130]
Similarly, the optimum range of the discharge power is appropriately selected according to the layer design. However, the total flow rate (F, unit: discharge gas (P, unit: W)) of the gas for supplying Si and the gas for supplying C is also selected. It is desirable to set the ratio P / F to ml / min (normal) in the range of 1 to 40, preferably 3 to 30, and optimally 5 to 20 when using a high frequency in the VHF band.
[0131]
Further, the temperature of the base 401 is appropriately selected in an optimum range according to the layer design. In a normal case, the temperature is preferably 150 to 350 ° C, more preferably 170 to 330 ° C, and most preferably 190 to 310 ° C. Is desirable.
[0132]
In particular, in the present invention, by changing the temperature at the time of forming the upper blocking layer, by gradually decreasing the amount of hydrogen atoms contained in the upper blocking layer toward the surface side, it is difficult for a sudden change in stress to occur, This is most desirable because an effect of suppressing cracks and peeling can be expected. The content of hydrogen atoms can be reduced on the surface side by gradually increasing the temperature toward the surface side. Regarding the temperature difference between the start time and the end time of the upper blocking layer, even if there is too much temperature difference, a difference in stress is generated, and if the temperature difference is too small, no effect is obtained. Specifically, the difference between the temperature at the start and the end of the formation of the upper blocking layer may be about 5 ° C. to 30 ° C., and it is desirable that the temperature is changed gradually from the start to the end.
[0133]
In the present invention, in order to form the upper blocking layer, the mixing ratio of the silicon-containing gas and the carbon-containing gas, the addition amount of the gas containing the conductivity controlling substance, the gas pressure in the reaction vessel, the discharge power, and the substrate temperature are preferably set. Although the numerical ranges include the above-mentioned ranges, these layer formation factors are not usually independently determined separately, but are determined based on mutual and organic relations to form an upper blocking layer having desired characteristics. It is desirable to determine the optimum value of each layer production factor based on the above.
[0134]
<Surface layer>
In the present invention, it is desirable to further form a surface layer 405 of a non-single-crystal material mainly composed of carbon on the photoconductive layer 403 and the upper blocking layer 404 formed on the base 401 as described above. . The surface layer 405 is provided in order to achieve the object of the present invention mainly in terms of polishing resistance, moisture resistance, continuous repeated use characteristics, electric pressure resistance, and use environment characteristics.
[0135]
The surface layer 405 is, for example, an amorphous material (hereinafter referred to as “a-SiC: H, X”) containing carbon as a base material, containing hydrogen atoms (H) and / or halogen atoms (X), and further containing silicon atoms. Is preferably used. Alternatively, one or more of a nitrogen atom and an oxygen atom may be further added thereto. Further, non-single-crystal carbon (aC: H, X), which is a material containing carbon as a base and containing hydrogen and / or halogen, is also preferably used.
[0136]
In the present invention, in order to effectively achieve the object, the surface layer 405 is formed by a vacuum deposited film forming method, with numerical conditions of film forming parameters appropriately set so as to obtain desired characteristics. Specifically, from the productivity of the electrophotographic photoreceptor, it is preferable to use the same deposition method as that for the photoconductive layer.
[0137]
For example, in order to form the surface layer 405 made of a-SiC: H, X by a glow discharge method, a source gas for supplying silicon capable of supplying silicon atoms (Si) and a carbon atom (C) are basically used. The source gas for supplying C that can supply hydrogen and the source gas for supplying H that can supply hydrogen atoms (H) and / or the source gas for supplying X that can supply halogen atoms (X) are decompressed. Is introduced into the reaction vessel in a desired gas state to generate a glow discharge in the reaction vessel, and the photoconductive layer 403 and the upper blocking layer 404 which are previously set at predetermined positions are formed on the substrate 401. What is necessary is just to form the layer which consists of a-SiC: H, X.
[0138]
In order to form the surface layer 405 having characteristics capable of achieving the object of the present invention, parameters such as the temperature of the substrate 401, the gas pressure in the reaction vessel, the gas type and its mixing ratio, the gas flow rate, the high frequency frequency and the electric power, etc. Is appropriately set so that the dynamic hardness (DHT 115) is 4900 to 12750 N / mm. ² (500-1300kgf / mm ² ). 4900N / mm ² (500kgf / mm ² ) Is not desirable in terms of the amount of shaving, and 12750 N / mm ² (1300kgf / mm ² If it is larger than (), the surface properties change and the cleaning property may deteriorate, which is not desirable.
[0139]
The temperature (Ts) of the base 401 is appropriately selected in an optimum range according to the layer design. In a normal case, the temperature is preferably 150 to 350 ° C, more preferably 170 to 330 ° C, and most preferably 190 to 310 ° C. It is desirable.
[0140]
Similarly, the gas pressure in the reaction vessel is appropriately selected in an optimum range according to the layer design. ^-2 ~ 2 × 10 ² Pa, preferably 5 × 10 ^-2 ~ 5 × 10Pa, optimally 1 × 10 ^-1 The pressure is preferably set to 2 × 10 Pa.
[0141]
As a gas that can be preferably used, a gas that can be used when forming the above-described upper blocking layer is mentioned. ₄ , CH ₄ Is preferable, and hydrogen, He, and Ar are optimal as the diluting gas, and they may be appropriately diluted before use.
[0142]
Similarly, the optimum range of the discharge power is also appropriately selected according to the layer design. For example, in the case of a-SiC: H, X, the discharge power (P, unit: W) and the silicon-containing gas and the carbon-containing gas It is desirable to set the ratio P / F to the total flow rate (F, unit: ml / min (normal)) in the range of 5 to 50. Further, in the non-single-crystal carbon film, it is desirable to set P / F (carbon-containing gas flow rate) in a range of 15 to 150. Further, as the frequency, a frequency band called a VHF band of 30 MHz or more is preferable, and a frequency band of about 250 MHz or less is preferable in view of various ease of handling. Further, it is most preferable to superimpose the frequencies of a plurality of VHF bands on the same electrode to suppress the discharge unevenness due to the standing wave from the viewpoint of improving the uniformity of the film.
[0143]
In the present invention, the above-mentioned range is mentioned as a desirable numerical range such as a substrate temperature, a gas pressure, a discharge power, and a frequency for forming a surface layer, but the conditions are not usually determined independently and separately. It is desirable to determine the optimum value based on mutual and organic relationships to form a surface layer having desired properties.
[0144]
In addition, in the photoreceptor of the present invention, between the substrate 401 and the photoconductive layer 403, a carrier having a polarity opposite to that of the above-described upper blocking layer is prevented from being injected from the substrate side. It is more preferable to provide a blocking layer. This lower blocking layer may be formed using a silicon-containing gas and a carbon-containing gas in the same manner as the upper blocking layer, or by appropriately combining a nitrogen-containing gas, an oxygen-containing gas, etc., instead of the carbon-containing gas. Thus, the stopping power and the adhesion may be improved. Alternatively, a high-resistance type blocking layer to which carbon, nitrogen, oxygen or the like is added in an appropriate combination may be used. However, holes are injected as an n-type semiconductor by appropriately adding a gas containing Group 15 of the periodic table. May be blocked.
[0145]
Next, an apparatus for forming an electrophotographic photosensitive member and a film forming method will be described in detail.
[0146]
FIG. 5 is an example of a deposited film forming apparatus that can suitably use a high frequency in a VHF band, and is a schematic configuration diagram of an apparatus that can suitably deposit an electrophotographic photosensitive member on a cylindrical substrate 501. It is.
[0147]
FIG. 5A shows an apparatus for manufacturing an amorphous silicon photoconductor in which a cathode electrode 504 is provided outside a reaction vessel 502 and a plurality of cylindrical substrates 501 are provided inside the reaction vessel 502. FIG. 5B is a cross-sectional view taken along line AA ′ of FIG. 5A.
[0148]
The apparatus shown in FIG. 5 combines high-frequency power having two kinds of frequencies oscillated from two high-frequency power supplies 507 and 508 in a matching box 509, applies the synthesized power to a power supply point of a high-frequency power branch 513, and In this configuration, power is supplied from a plurality of cathode electrodes 504 provided outside to the inside of the reaction vessel 502 to generate plasma in the reaction vessel 502 to form a deposited film. With such a configuration, it is possible to substantially eliminate the influence of the standing wave appearing on the electrode or the base caused by the short wavelength of VHF, and to significantly improve the uniformity of the film. It is.
[0149]
In order to efficiently introduce the high-frequency power emitted from the cathode electrode 504 into the reaction vessel 502, ceramics, which is a dielectric, are used on the side wall of the cylindrical reaction vessel 502. Specific examples of ceramic materials include alumina, titanium dioxide, aluminum nitride, boron nitride, zircon, cordierite, zircon-cordierite, silicon oxide, and beryllium mica-based ceramics. Of these, alumina, aluminum nitride, and boron nitride are preferred from the viewpoints of suppressing contamination of impurities during vacuum processing and heat resistance.
[0150]
Further, the reaction apparatus shown in FIG. 5 has a configuration in which six cylindrical substrates 501 are installed at equal intervals on the same circumference in a reaction vessel 502. The number of the cylindrical substrates 501 is six in FIG. 5, but can be arbitrarily changed according to the diameter of the reaction vessel and the cylindrical substrates. In addition, six gas introduction pipes 503 for introducing gas are provided at equal intervals on the same circumference outside the circle where the cylindrical base is arranged. The number of the gas introduction pipes can be any number as long as the gas can be supplied uniformly.
[0151]
The connection between the high-frequency power branching unit 513 and each of the cathode electrodes 504 may be connected via a capacitor.
[0152]
The outline of the deposition film formation using the apparatus of FIG. 5 will be described below.
[0153]
First, the cylindrical substrate 501 is set in the reaction vessel 502, and the inside of the reaction vessel 502 is exhausted through an exhaust pipe by an exhaust device (not shown). Subsequently, the cylindrical substrate 501 is heated and controlled to a predetermined temperature of about 200 ° C. to 300 ° C. by a heater (not shown) while flowing an inert gas.
[0154]
When the temperature of the cylindrical substrate 501 reaches a predetermined temperature, a raw material gas is introduced into the reaction vessel 502 via a gas supply and adjustment means (not shown). Thereafter, the pressure in the reaction vessel 502 is set to a predetermined pressure of 0.05 to 40 Pa, preferably 0.1 to 20 Pa, using an exhaust conductance control means (not shown). After confirming that the pressure in the reaction vessel 502 has stabilized, high-frequency power is supplied from the high-frequency power supplies 507 and 508 to the cathode electrode 504 via the matching box 509. As a result, high-frequency powers of two different frequencies are introduced into the reaction vessel 502, glow discharge occurs in the reaction vessel 502, and the source gas is excited and dissociated to form a deposited film on the cylindrical substrate. During the formation of the deposited film, the cylindrical substrate 501 is rotated at a predetermined speed by the motor 511 via the rotation shaft 510, so that the deposited film is formed over the entire surface of the cylindrical substrate 501.
[0155]
After the desired film thickness is formed, the supply of the high-frequency power is stopped, then the supply of the source gas is stopped, and the formation of the deposited film is completed. By repeating the same operation a plurality of times, a light receiving layer having a desired multilayer structure is formed.
[0156]
The high frequency power supplies 507 and 508 preferably oscillate at a frequency in the VHF band. If the frequency is too low, the deposition rate will be low, and if it is too high, high frequency propagation will not be compatible with the device. Therefore, it is desirable to be able to output power of a frequency within a certain range. In particular, the relationship between the oscillation frequencies is such that the high-frequency power supply 507 supplies a first high-frequency power (frequency f1, power value P1), and the high-frequency power supply 508 supplies a second high frequency power (frequency f2, power value P2). When the second high-frequency power supply for supplying
30MHz ≦ f2 <f1 ≦ 250MHz
0.1 ≦ P2 / (P1 + P2) ≦ 0.9
By doing so, the balance is most preferable and preferable from the viewpoints of deposition, characteristics, and unevenness suppression.
[0157]
Particularly, in the upper blocking layer formed at such a high frequency, the mobility of holes is high, which is preferable. In addition, the surface layer formed at such a high frequency of a high frequency is more preferable because both hardness and transparency can be increased. Therefore, in order to perform uniform film deposition over a large area using such a high frequency high frequency, it is most preferable to use a technique of superimposing two high frequencies in the above-described range.
[0158]
The first high-frequency power supply may be provided with a high-pass filter having a cut-off frequency characteristic lower than f1 and higher than f2. Similarly, the second high-frequency power supply may be provided with a low-pass filter having a cutoff frequency characteristic higher than f2 and lower than f1. The higher the frequency selectivity is, the more preferable it is because the other power flowing to each high-frequency power source can be reduced.
[0159]
When the frequency range is 50 MHz or more, the deposition rate is further increased, which is more preferable.
[0160]
Further, the range of the power is
0.2 ≦ P2 / (P1 + P2) ≦ 0.7
It is more preferable that the upper limit of the power ratio is set to f2 / f1, because the stability of discharge is enhanced.
[0161]
Further, the range of the frequency,
0.5 <f2 / f1 ≦ 0.9
It is more preferable to set the value within the range, since a higher standing wave suppressing effect can be obtained.
[0162]
In the case of the apparatus as shown in FIG. 5, for example, a method in which f1 and f2 are independently supplied for each electrode can be considered, but more preferably, f1 and f2 are preferably supplied from the same direction of the same rod-shaped electrode. . In practice, after f1 and f2 are combined (superimposed), power is uniformly supplied to each cathode electrode from the same direction via a branch. Such a configuration is preferable because a standing wave suppressing effect can be more effectively obtained.
[0163]
【Example】
Hereinafter, the present invention will be described specifically with reference to Experimental Examples and Examples, but the present invention is not limited thereto.
[0164]
<< Experimental example 1 >>
Using a vacuum processing apparatus shown in FIG. 5, a lower blocking layer, a photoconductive layer, an upper blocking layer, and a surface layer were formed on a mirror-finished aluminum cylinder (substrate) having a diameter of 80 mm under the conditions shown in Table 1. The deposition was performed to prepare an electrophotographic photosensitive member.
[0165]
The deposition film formation using the apparatus of FIG.
[0166]
First, the reaction vessel 502 was exhausted through an exhaust pipe 505 by an exhaust device (not shown). Subsequently, the substrate was heated and controlled to 190 ° C. by a heating element (not shown) while supplying 1000 ml / min (normal) He into the reaction vessel 502 from a source gas supply means (not shown).
[0167]
Next, the supply of He was stopped, and the reaction vessel 502 was evacuated by an exhaust device (not shown). Then, an electrophotographic photosensitive member was deposited on an aluminum cylinder according to the deposition film forming conditions shown in Table 1. When forming the upper blocking layer, the set temperature of the heater was increased by 30 ° C. during the film formation in order to improve the adhesion.
[0168]
Further, between the upper blocking layer and the surface layer, there is provided a changing region whose composition is gently changed in order to prevent interference by laser. Converted from the deposition rate and the change time, it is estimated to be about 100 nm. In addition, as a high-frequency power source, two power sources (100 MHz and 60 MHz) having different frequencies were used, and the respective powers were superposed at a ratio of 1: 1 to form a deposited film. During the film deposition, the substrate holder was rotated, and the film was deposited evenly so as not to cause unevenness in the circumferential direction.
[0169]
After forming the deposited film, the reaction vessel 502 is purged with Ar, ₂ The deposited film was taken out by gas leakage.
[0170]
Separately, a sample was prepared in which films were deposited under the same conditions for only each layer shown in Table 1. Each of the single layer samples was subjected to quantitative analysis, and the components of each layer of the electrophotographic photosensitive member were estimated based on the results. Under the conditions of Table 1, the value of C / (Si + C) in the upper blocking layer is about 0.3, the amount of boron is about 3000 ppm with respect to Si, and the value of C / (Si + C) in the surface layer is about 0. .7 was determined by secondary ion mass spectrometry (SIMS) of the prepared membrane.
[0171]
[Table 1]

The produced photoreceptor is set on an idle rotating machine (a product obtained by modifying a Canon iR-5000 into a negative charging system for experiments and removing a developing device, a cleaner, a transfer material, etc.) based on an electrophotographic apparatus. And the potential characteristics were evaluated.
[0172]
As the charger, a conductive roller charger (upstream in the moving direction) and a magnetic brush charger (downstream in the moving direction) were used. The angle formed by the two chargers was 25 degrees.
[0173]
A DC voltage of -550 V was applied to the magnetic brush charger, and an alternating voltage (1.2 kVpp, 1.0 kHz) was further applied.
[0174]
The magnetic particles for charging are oxidized and reduced on the ferrite surface to adjust the resistance. The average particle size is 25 μm, and the saturation magnetization is 2.5 × 10 ^-1 Wb / m ² (200 emu / cm ³ ), Resistance value is 1.9 × 10 ⁶ Ω. The resistance value is 228 mm in the bottom area. ³ 650 kPa (6.6 kgf / cm) ² ), And measured by applying a voltage of 100V. Further, a voltage of -1000 V was applied to the conductive roller. The material of the conductive roller charger is made of stainless steel as the core metal, and as the elastic layer, a foamed solid elastic body mainly using urethane or the like, carbon, TiO 2 or the like is used. ₂ And a metal oxide such as ZnO and having a volume resistivity of 1E4 to 1E13 Ω · cm.
[0175]
At this time, the process speed was 200 to 700 mm / s. As a result, t / S was 8.02 μm / s at the maximum. In addition, an LED having a wavelength of 660 nm was used for static elimination light, and the amount of light at each process speed was 4 lx · s. In the measurement of the charging ability, the surface potential of the photoreceptor was measured by a potential sensor of a surface electrometer (Model 344 manufactured by TREK) set at the developing device position of the electrophotographic apparatus, and this value was defined as the charging ability. The charging ability was measured at 18 points in the axial direction, and the in-plane unevenness of the charging ability was evaluated in the axial and circumferential directions.
[0176]
The results obtained as described above are shown in FIGS.
[0177]
<< Comparative Experimental Example 1 >>
The photoreceptor produced in Experimental Example 1 was set in an idle rotating machine based on Experimental Example 1 and an electrophotographic apparatus, and the potential characteristics were evaluated.
[0178]
As a charger, a corona charger and a magnetic brush charger were used.
[0179]
The corona charger had a charger width of 33 mm, a grid voltage of −600 V, and a primary current flowing through the charging wire was about −1500 μA. A DC voltage of -550 V was applied to the magnetic brush charger, and an alternating voltage (1.2 kVpp, 1.0 kHz) was further applied. The resistance value of the magnetic particles is 1.9 × 10 ⁶ Ω and other conditions were the same as in Experimental Example 1.
[0180]
At this time, the process speed was 200 to 700 mm / s, the LED having a wavelength of 660 nm was used as the charge removing light, and the light quantity at each process speed was 4 lx · s.
[0181]
With the above configuration, the charging ability and the charging ability unevenness were evaluated in the same manner as in Experimental Example 1.
[0182]
The obtained results are shown in FIGS. 6 and 7 together with the results of Experimental Example 1.
[0183]
FIG. 6 shows the transition of the charging ability with respect to the process speed. For all three types of chargers, the charging ability (at all chargers around 400 V) when the process speed is 200 mm / s is set to 1, and the increase / decrease relative to this value is indicated by a relative value. In the corona charger, the charging ability decreases as the process speed increases. This is because the charger is of a constant current type, and the amount of charge is a product of the passage time of the charger determined by the process speed. Therefore, the charging time monotonously decreases as the passage time decreases. On the other hand, the magnetic brush charger of the contact charging type and the conductive roller + magnetic brush charger have a very small dependence on the process speed because of the constant voltage type. In addition, in the contact charging method, when the process speed is reduced, the charging ability is reduced. This is because the dark decay of the photoconductor is relatively large in the a-Si photoconductor.
[0184]
Further, as compared with the case of using only the magnetic brush charger, in the system of the conductive roller and the magnetic brush of Experimental Example 1, the charging performance is improved more than when the process speed is 200 mm / s. This seems to be due to the use of a multi-stage charger. That is, it is considered that the pre-exposure carrier was sufficiently discharged by the conductive roller, and charging by the magnetic brush charger was performed very efficiently.
[0185]
FIG. 7 shows the circumferential unevenness (unit: V) of the charging ability with respect to the process speed. FIG. 7 shows that the contact charging system, which is also a constant voltage type, is effective in suppressing circumferential unevenness. Furthermore, it is shown that the peripheral unevenness is further suppressed by using a multi-stage contact charging as in Experimental Example 1.
[0186]
6 and 7, when a multi-stage contact charging system is used as the charging system, the charging performance and its unevenness are most preferable, and the charging performance is remarkably improved in the region where the process speed is 300 mm / s or more. As a result, it was found that the effects of the present invention can be more suitably obtained.
[0187]
<< Experimental example 2 >>
A lower blocking layer, a photoconductive layer, an upper blocking layer, and a surface layer were formed in this order on an 80 mm-diameter mirror-finished aluminum cylinder (substrate) using the vacuum processing apparatus shown in FIG. The electrophotographic photoreceptor was completed. At this time, a lower blocking layer and a photoconductive layer were formed under the conditions shown in Table 1, an upper blocking layer was formed under the conditions shown in Table 2, and a surface layer was formed under the conditions shown in Table 3. A photoreceptor was prepared. Note that a variable region for smoothly changing the gas flow rate, the electric power, and the like is provided between the upper blocking layer and the surface layer as in Experimental Example 1.
[0188]
[Table 2]

[0189]
[Table 3]

The upper blocking layer was varied within the range shown in Table 2 to prepare six types of photoconductors A to F. Regarding the amount of boron to be added, the controllability of valence electron control differs depending on the composition ratio of carbon and silicon. Therefore, when the amount of carbon is increased, the amount of boron needs to be increased. This is determined by separately performing an experiment for appropriately adjusting the amount of boron while measuring the resistance value of the film. SIMS measurement revealed that the obtained films had the compositions shown in Table 4, respectively. The composition C / (Si + C) of the surface layer was 0.75.
[0190]
[Table 4]

The produced photoreceptor is set on an idle rotating machine (a device obtained by modifying a Canon iR-5000 into a negative charging system for experiments and removing a developing device, a cleaner, a transfer material, etc.) based on an electrophotographic apparatus. The potential characteristics were evaluated in the same manner as in Experimental Example 1.
[0191]
As the charger, a multi-stage charger of the same conductive roller charger and magnetic brush charger as in Experimental Example 1 was used. The angle formed by the two chargers was 25 degrees, and the type of the magnetic material and the applied voltage were the same as those in Experimental Example 1. The process speed was fixed at 350 mm / s, and the static elimination light and the like were the same as in Experimental Example 1.
[0192]
The results obtained as described above are shown in FIGS.
[0193]
<< Comparative Experimental Example 2 >>
The photoconductors A to F prepared in Experimental Example 2 were set in an idle rotating machine based on the same electrophotographic apparatus as in Experimental Example 2, and the potential characteristics were evaluated in the same manner as in Experimental Example 2.
[0194]
The charging was performed using two types of corona charger and magnetic brush charger. The type of magnetic material, applied voltage, and the like were the same as those in Experimental Example 1. The process speed was fixed at 350 mm / s, and the static elimination light and the like were the same as in Experimental Example 1.
[0195]
The results obtained above are shown in FIGS. 8 and 9 together with the results of Experimental Example 2.
[0196]
8 and 9, the result on the photosensitive member A is set as a reference (= 1), and is expressed as a relative value. That is, for example, in the corona charging shown by the dotted line in FIG. The values are plotted. Similarly, the plot of the magnetic brush charger alone shown by the broken line and the plot of the multi-stage system shown by the solid line are based on the values in combination with the photoconductor A, respectively.
[0197]
As can be seen from FIGS. 8 and 9, in the contact charging, the photoconductors B to F all have an improved charging ability as compared with the photoconductor A, and the charging ability unevenness tends to be improved. However, the degree of improvement or improvement in corona charging is small. Further, even in the case of contact charging, the combination of a multi-stage conductive roller charger and a magnetic brush charger is most effective in improving charging performance and reducing unevenness. Although the reason for this is not known, it is believed that the matching between the photoreceptor layer structure of the present invention and the multi-stage contact charging process of the present invention is very good.
[0198]
From the above results, when the upper blocking layer is provided, the matching with the multi-stage charging method of the present invention is the best when the silicon-carbon composition and the concentration of Group 13 atoms in the periodic table with respect to silicon are appropriate. It was found that the effect of the present invention can be further obtained.
[0199]
<< Experimental example 3 >>
A lower blocking layer, a photoconductive layer, an upper blocking layer, and a surface layer were formed in this order on an 80 mm-diameter mirror-finished aluminum cylinder (substrate) using the vacuum processing apparatus shown in FIG. The electrophotographic photoreceptor was completed. At this time, a lower blocking layer and a photoconductive layer were formed under the conditions shown in Table 1, an upper blocking layer was formed under the conditions shown in Table 5, and a surface layer was formed under the conditions shown in Table 6. A photoreceptor was prepared. Note that a variable region for smoothly changing the gas flow rate, the electric power, and the like is provided between the upper blocking layer and the surface layer as in Experimental Example 1.
[0200]
[Table 5]

[0201]
[Table 6]

The surface layer composed of aC was varied within the range shown in Table 6, and five types of photoconductors G to K were prepared. In this experimental example, in order to widen the range of the hardness, this is achieved by varying the gas flow rate and the power value. Regarding the hardness of the surface layer, there are factors other than the electric power. However, the higher the electric power, the easier the hardness becomes, and the lower the electric power, the lower the hardness.
[0202]
Separately, a sample was prepared by depositing a film under the same conditions only for the upper blocking layer shown in Table 5, and quantitative analysis was performed in the same manner as in Experimental Example 1. The composition C / (Si + C) of the upper blocking layer was 0.32, and the B content was 3000 ppm with respect to silicon.
[0203]
Further, a sample of a single layer under the same conditions as the respective layers shown in Tables 5 and 6 was deposited on a Si wafer and subjected to measurement using a dynamic hardness tester (DUH-201, manufactured by Shimadzu Corporation). Here, the indenter used for the dynamic hardness measurement was a triangular cone indenter with a ridge angle of 115 ° (radius of curvature of the tip is 0.1 μm or less), and the value of the dynamic hardness was 0.98 mN (0. 1 gf) The value when the indenter is pushed down until the load is reached.
[0204]
As a result, it was found that each of the obtained films had a dynamic hardness as shown in Table 7.
[0205]
The dynamic hardness referred to here is based on the principle of measurement, and quantifies plastic deformation such as Vickers hardness, which is commonly used (pressing an indenter, measuring the size of the imprint, and calculating the hardness. Method). That is, since the deformation caused by pushing the indenter into the deposited film by a very small amount is measured, the influence of the surface roughness of the film and the force corresponding to the elastic deformation are also measured. By using the surface shape and hardness including elastic deformation as indices in this way, the durability of the photoreceptor to the environment to which it is actually exposed, specifically, the shaving characteristics as a surface layer, toner, magnetic particles, and blades It is considered that there is a correlation with the frictional characteristics of the steel.
[0206]
[Table 7]

The produced photoreceptor was set in an electrophotographic apparatus (a Canon iR-5000 modified to a negative charging system for experiments), and a durability test was performed using actual copying operations.
[0207]
As the charger, a multi-stage charger of the same conductive roller charger and magnetic brush charger as in Experimental Example 1 was used. The angle formed by the two chargers was 25 degrees. The type of magnetic material, applied voltage, and the like were the same as those in Experimental Example 1. Further, the process speed was fixed at 400 mm / s, and the static elimination light and the like were the same as in Experimental Example 1. Developing device and cleaner were used for iR-5000, and Canon test chart (part number FY9-9060A) was used as a copy manuscript in an environmental test chamber at 23 ° C and 50% normal environment. A paper passing durability test was performed on 100,000 sheets of recycled paper (Canon recycled paper EW-500).
[0208]
After the durability test, a solid white image (zero laser output) was output as an evaluation of the cleaning property, and the degree of contamination of the obtained image was checked. For quantitative determination, the area of the A4 image that was soiled was calculated and compared.
[0209]
Next, as an evaluation of uneven shaving, first, a halftone (one dot, one space) by a laser pattern was output, and the density difference on the image was evaluated by a reflection densitometer (manufactured by Macbeth). This density difference reflects the height difference between the most shaved part and the unshaved part.
[0210]
Table 9 shows the obtained results.
[0211]
<< Comparative Experimental Example 3 >>
Photoconductor L was prepared in the same manner as in Experimental Example 3. At this time, only the surface layer was prepared under the conditions listed in Table 8.
[0212]
The hardness of the film obtained by measuring the hardness of the surface layer of the obtained photoreceptor was 4120 N / mm. ² (420kgf / mm ² )Met.
[0213]
[Table 8]

The produced photoreceptor was set in the same electrophotographic apparatus as in Experimental Example 3 (a Canon iR-5000 modified to a negative charging system for the experiment), and a 100,000-sheet durability test was performed in the same manner. Next, the cleaning property and the degree of uneven scraping were evaluated by the same evaluation method as in Experimental Example 3.
[0214]
Table 9 shows the obtained results. In Table 9, based on the evaluation results obtained with the photoconductor L prepared in Comparative Experimental Example 3, the results were ranked according to the following criteria.
[0215]
In the evaluation of the cleaning property, the area of the stained portion was compared with the value of the photoreceptor L and classified into the following four types.
[0216]
A: The area of the stained portion is reduced by 20% or more as compared with the photosensitive member L.
：: The area of the stained portion is reduced by 10 to 20% as compared with the photosensitive member L.
Δ: The area of the stained portion is less than 10% as compared with the photosensitive member L (substantially equivalent).
×: The area of the stained portion is larger than that of the photoconductor L
In the evaluation of the unevenness shaving amount, the difference between the maximum value and the minimum value of the surface layer shaving amount was compared with the value of the photoconductor L, and classified into the following four types.
[0217]
A: The difference in the shaving amount is reduced by 20% or more compared to the photosensitive member L.
：: The difference in the shaving amount is reduced by 10 to 20% as compared with the photosensitive member L.
Δ: The difference in the shaved amount is less than 10% as compared with the photosensitive member L (substantially equivalent).
×: The difference in the shaving amount is larger than that of the photoconductor L
[0218]
[Table 9]

As can be seen from Table 9, the dynamic hardness is 4120 N / mm ² (420kgf / mm ² Compared with the photoreceptor L, the photoreceptors G to K having a high hardness have small shaving unevenness, that is, a small step difference between the most shaved portion and the least shaved portion. In particular, regarding the photoconductors G to I, not only the shaving unevenness but also the absolute amount of shaving was very small. Further, the cleaning performance of all of the photoconductors H to K is better than that of the photoconductor L. On the other hand, the value of the photoconductor G was hardly different from the value of the photoconductor L. Although this is unknown in detail, I think as follows. What is common to amorphous silicon carbide and amorphous carbon is that in order to increase the hardness of the film, it is necessary to increase the power value per unit gas amount. is there. It is considered that when such high power is applied, the film becomes hard due to the effect of plasma self-bias (ion bombardment). At this time, it is considered that if the ion impact is too large, the surface is likely to be damaged, and it is considered that the surface property is changed due to the damage and the improvement of the cleaning property is hindered. From this, in order to obtain the effect of the present invention, the dynamic hardness of the surface layer must be 4900 to 12750 N / mm. ² (500-1300kgf / mm ² ) Was found to be most desirable.
[0219]
<< Experimental example 4 >>
A 7059 glass substrate (38.1 mm (1.5 inches) × 25.4 mm (1 inch) × 0.5 mm) manufactured by Corning Co., Ltd. on an 80 mm-diameter aluminum cylinder using the vacuum processing apparatus shown in FIG. 5 mm) and a Si wafer having a diameter of 25.4 mm (1 inch) were set as substrates. The portion where the glass and the Si wafer were placed was shaved horizontally, so that the glass was in close contact with the aluminum cylinder. Glass and Si wafers were held down with stainless steel claws to prevent them from falling. Such a substrate was heated by a heater before film formation similarly to Experimental Example 1, and the surface was adjusted to a predetermined temperature. Next, under the conditions shown in Table 10, the gas flow rates, the ratios thereof, and the values of the high-frequency power were variously changed, and single-layer films M to Q corresponding to the surface layer were formed.
[0220]
[Table 10]

The hardness of the obtained film was measured by a dynamic hardness meter in the same manner as in Experimental Example 3. The composition of the film whose hardness was measured was quantified by secondary ion mass spectrometry (SIMS). Table 11 shows the measurement results.
[0221]
From Table 11, it can be seen that when forming a surface layer made of amorphous silicon carbide, in order to obtain a suitable hardness in the present invention, it is preferable that the value of the composition C / (Si + C) is 0.7 or more. I understood.
[0222]
<< Comparative Experimental Example 4 >>
A single-layer film R corresponding to the surface layer was formed in the same manner as in Experimental Example 4. At this time, in Table 10, SiH ₄ Gas, CH ₄ The gas was 33 and 67 ml / min (normal), respectively. SIMS measurement revealed that the film had a composition C / (Si + C) of 0.65 as shown in Table 11. When the dynamic hardness of this film was measured, the dynamic hardness was 4120 N / mm. ² (420kgf / mm ² ), And sufficient hardness could not be obtained.
[0223]
[Table 11]

<< Experimental example 5 >>
A lower blocking layer, a photoconductive layer, an upper blocking layer, and a surface layer are formed in this order on a mirror-finished aluminum cylinder (substrate) having a diameter of 108 mm using the vacuum processing apparatus shown in FIG. The electrophotographic photoreceptor was completed. At this time, a lower blocking layer and a photoconductive layer were formed under the conditions shown in Table 1, an upper blocking layer was formed under the conditions shown in Table 12, and a surface layer was formed under the conditions shown in Table 13. A photoreceptor was prepared. Note that a variable region for smoothly changing the gas flow rate, the electric power, and the like is provided between the upper blocking layer and the surface layer as in Experimental Example 1.
[0224]
[Table 12]

[0225]
[Table 13]

The thickness of the upper blocking layer was varied within the range shown in Table 12, and photoreceptors S, T, and U having three types of upper blocking layers of 0.05, 0.3, and 0.4 were prepared. The composition C / (Si + C) of the upper blocking layer was 0.36, and the B content with respect to Si was 3000 ppm. The composition C / (Si + C) of the surface layer was 0.71.
[0226]
The produced photoreceptor is set on an idle rotating machine (a product obtained by modifying a Canon GP-605 into a negative charging system for experiments and removing a developing device, a cleaner, a transfer material, etc.) based on an electrophotographic apparatus. The potential characteristics were evaluated in the same manner as in Experimental Example 1.
[0227]
The charger is a multi-stage charger of the same conductive roller charger and magnetic brush charger as in Experimental Example 1, and the type of magnetic material and applied voltage were the same as in Experimental Example 1. Here, the time S (second) between the chargers was changed by changing the angle at which the two chargers were arranged to 17 degrees and 30 degrees. At this time, the charging device having the arrangement angle of 17 degrees was designated as process A, and the charging device having 30 degrees was designated as process B. Further, the process speed was set to 450 mm / s and 500 mm / s. The static elimination light and the like were the same as in Experimental Example 1.
[0228]
FIG. 10 shows the obtained results. In FIG. 10, ranking was performed based on the evaluation result obtained under the condition of the largest t / S (μm / s) based on the following criteria. That is, when the photoconductor U (the thickness of the upper blocking layer is 0.4 μm) is used and combined with the process A (the angle between the two chargers is 17 degrees), when the process speed is 500 mm / s, t / S is 12.5, which is the largest. Using the result of this combination as a reference (= 1), the relationship between t / S and unevenness in charging ability was plotted.
[0229]
As can be seen from FIG. 10, the smaller the value of t / S is, the higher the effect of improving the unevenness is. In particular, the effect of improving the unevenness is large in the region where t / S is 10 or less. This seems to mean that discharge of the charge removing optical carrier is performed more completely, and the smaller the t / S, the more the matching between the photoreceptor layer configuration of the present invention and the multi-stage contact charging process of the present invention. It shows that it becomes good.
[0230]
From the above results, when the upper blocking layer is provided, the relationship t / S between the film thickness t (μm) of the upper blocking layer and the time S (s) for the photoconductor to pass between the two chargers is: It has been found that the smaller the value, the better, especially when the value is 10 or less, the effect of the present invention can be obtained most preferably.
[0231]
(Example 1)
Using a vacuum processing apparatus shown in FIG. 5, a lower blocking layer, a photoconductive layer, an upper blocking layer, and a surface layer were formed on a mirror-finished aluminum cylinder (base) having a diameter of 80 mm in the order shown in Table 14 under the conditions shown in Table 14. The deposition was performed to prepare an electrophotographic photosensitive member. The inner diameter of the reaction vessel 502 in FIG. 5 was 500 mm, the number of aluminum cylinders was 6, and two high frequencies were 90 MHz and 50 MHz. Each high frequency power was superimposed at 1: 1.
[0232]
Prior to the preparation of the photoreceptor, films corresponding to the respective layers shown in Table 14 were formed in advance and quantitative analysis was performed. Under the conditions of Table 12, the value of C / (Si + C) of the upper blocking layer is about 0.25, the amount of boron is about 2000 ppm relative to Si, and the value of C / (Si + C) of the surface layer is about 0. 0.8 was found by secondary ion mass spectrometry (SIMS) of the prepared membrane. When forming the upper blocking layer, the set temperature of the heater was increased by 10 ° C. during the film formation in order to improve the adhesion. Further, between the upper blocking layer and the surface layer, there is provided a changing region whose composition is gently changed in order to prevent interference by laser. Converted from the deposition rate and the change time, it is estimated to be about 200 nm. During the film deposition, the substrate holder was rotated, and the film was deposited uniformly so as not to cause unevenness in the circumferential direction.
[0233]
[Table 14]

The produced photoreceptor was set in a modified machine based on an electrophotographic apparatus (a Canon iR-5000 modified into a negative charging system for experiments), and the potential characteristics were evaluated.
[0234]
As the charger, a multi-stage charger of the same conductive roller charger and magnetic brush charger as in Experimental Example 1 was used. A DC voltage of -550 V was applied to the magnetic brush charger, and an alternating voltage (1.2 kVpp, 1.0 kHz) was further applied. The resistance value of the magnetic particles is 1.9 × 10 ⁶ Ω and other conditions were the same as in Experimental Example 1. Further, a voltage of -1000 V was applied to the conductive roller.
[0235]
At this time, the process speed was 400 mm / s, the angle formed by the two chargers was 20 degrees, an LED having a wavelength of 660 nm was used for static elimination light, and the amount of light was 4 lx · s. Further, iR-5000 was used for the developing unit and the cleaner.
[0236]
The charging ability at the position of the developing device was good, the peripheral unevenness was very small, no sweeping unevenness was observed by the magnetic brush, and the sensitivity, dark decay, ghost, and residual potential were also good. An image evaluation was performed using a test chart with the developing device inserted. The image quality was good, and there was almost no density unevenness, and no fog or blur was observed.
[0237]
Next, using this electrophotographic apparatus, a paper passing durability test was performed for 50,000 sheets in a low-temperature and low-humidity environment of 10 ° C. and 15%, a normal environment of 23 ° C. and 50%, and a high-temperature and high-humidity environment of 33 ° C. and 90%. However, no uneven scraping, poor cleaning, image defects due to image deletion, etc. were observed at all, and it was found that good images could be continuously obtained.
[0238]
(Example 2)
Using a vacuum processing apparatus shown in FIG. 5, a lower blocking layer, a photoconductive layer, an upper blocking layer, and a surface layer were formed on a mirror-finished aluminum cylinder (substrate) having a diameter of 108 mm under the conditions shown in Table 15 in the order shown in Table 15. The deposition was performed to prepare an electrophotographic photosensitive member. The inner diameter of the reaction vessel 502 in FIG. 5 was 400 mm, the number of aluminum cylinders was three, and two high frequencies were 100 MHz and 70 MHz. Each high frequency power was superimposed at 1: 1.
[0239]
Prior to the preparation of the photoreceptor, films corresponding to the respective layers shown in Table 15 were prepared in advance, and quantitative analysis was performed. Under the conditions of Table 13, the value of C / (Si + C) in the upper blocking layer is about 0.27, the amount of boron is about 2400 ppm with respect to Si, and the value of C / (Si + C) in the surface layer is about 0. .78 as determined by secondary ion mass spectrometry (SIMS) of the prepared membrane. During the formation of the upper blocking layer, the set temperature of the heater was increased by 20 ° C. during the film formation in order to improve the adhesion. Further, between the upper blocking layer and the surface layer, there is provided a changing region whose composition is gently changed in order to prevent interference by laser. Converted from the deposition rate and the change time, it is estimated to be about 200 nm. During the film deposition, the substrate holder was rotated, and the film was deposited evenly so as not to cause unevenness in the circumferential direction.
[0240]
[Table 15]

The produced photoreceptor was set in a modified machine based on an electrophotographic apparatus (a product obtained by modifying a Canon GP-605 into a negative charging system for experiments), and the potential characteristics were evaluated.
[0241]
As the charger, a multi-stage charger of the same conductive roller charger and magnetic brush charger as in Experimental Example 1 was used. A DC voltage of -550 V was applied to the magnetic brush charger, and an alternating voltage (1.2 kVpp, 1.0 kHz) was further applied. The resistance value of the magnetic particles is 1.9 × 10 ⁶ Ω and other conditions were the same as in Experimental Example 1. Further, a voltage of -1000 V was applied to the conductive roller.
[0242]
At this time, the process speed was 450 mm / s, the angle formed by the two chargers was 30 degrees, an LED having a wavelength of 660 nm was used for static elimination light, and the amount of light was 4 lx · s. As for the developing device and the cleaner, those of GP-605 were used.
[0243]
The charging ability at the position of the developing device was good, the peripheral unevenness was very small, no sweeping unevenness was observed by the magnetic brush, and the sensitivity, dark decay, ghost, and residual potential were also good. An image evaluation was performed using a test chart with the developing device inserted. The image quality was good, and there was almost no density unevenness, and no fog or blur was observed.
[0244]
Next, using this electrophotographic apparatus, a paper passing durability test was performed for 50,000 sheets in a low-temperature and low-humidity environment of 10 ° C. and 15%, a normal environment of 23 ° C. and 50%, and a high-temperature and high-humidity environment of 33 ° C. and 90%. However, no uneven scraping, poor cleaning, image defects due to image deletion, etc. were observed at all, and it was found that good images could be continuously obtained.
[0245]
(Example 3)
Using a vacuum processing apparatus shown in FIG. 5, a lower blocking layer, a photoconductive layer, an upper blocking layer, and a surface layer were formed on a mirror-finished aluminum cylinder (substrate) having a diameter of 60 mm under the conditions shown in Table 16 in this order. The deposition was performed to prepare an electrophotographic photosensitive member. The inner diameter of the reaction vessel 502 in FIG. 5 was 500 mm, the number of aluminum cylinders was seven, and two high frequencies were 80 MHz and 60 MHz. Each high frequency power was superimposed at 1: 1.
[0246]
Prior to the preparation of the photoreceptor, films corresponding to the respective layers shown in Table 14 were formed in advance and quantitative analysis was performed. Under the conditions of Table 16, the value of C / (Si + C) in the upper blocking layer is about 0.19, the amount of boron is about 1000 ppm with respect to Si, and the value of C / (Si + C) in the surface layer is about 0. .85 as determined by secondary ion mass spectrometry (SIMS) of the prepared membrane. When forming the upper blocking layer, the set temperature of the heater was increased by 10 ° C. during the film formation in order to improve the adhesion. Further, between the upper blocking layer and the surface layer, there is provided a changing region whose composition is gently changed in order to prevent interference by laser. Converted from the deposition rate and the change time, it is estimated to be about 300 nm. During the film deposition, the substrate holder was rotated, and the film was deposited evenly so as not to cause unevenness in the circumferential direction.
[0247]
[Table 16]

The four photoconductors thus prepared were set in a modified machine based on an electrophotographic apparatus (a machine modified from a Canon CLC-5000 as a base machine to an a-Si system), and the potential characteristics were evaluated. .
[0248]
As the charger, a multi-stage charger of the same conductive roller charger and magnetic brush charger as in Experimental Example 1 was used. A DC voltage of -550 V was applied to the magnetic brush charger, and an alternating voltage (1.2 kVpp, 1.0 kHz) was further applied. The resistance value of the magnetic particles is 1.9 × 10 ⁶ Ω and other conditions were the same as in Experimental Example 1. Further, a voltage of -1000 V was applied to the conductive roller.
[0249]
At this time, the process speed was 400 mm / s, the angle formed by the two chargers was 20 degrees, an LED having a wavelength of 660 nm was used for static elimination light, and the light amount was 4 lx · s. As for the developing device, toner, cleaner and the like, those of CLC-5000 were used.
[0250]
The charging ability at the developing device position for each color was good, the peripheral unevenness was very small, no sweeping unevenness was observed by the magnetic brush, and the sensitivity, dark decay, ghost, and residual potential were also good. Further, the characteristic unevenness between the colors was very small. Next, an image evaluation was performed using a test chart by inserting a developing unit. The image quality was good, and there was almost no density unevenness, no fog, no blur, etc., and a high-quality full-color image was obtained. Was.
[0251]
Next, using this electrophotographic apparatus, a paper passing durability test was performed for 50,000 sheets in a low-temperature and low-humidity environment of 10 ° C. and 15%, a normal environment of 23 ° C. and 50%, and a high-temperature and high-humidity environment of 33 ° C. and 90%. However, no uneven scraping, poor cleaning, image defects due to image deletion, etc. were observed at all, and it was found that good images could be continuously obtained.
[0252]
【The invention's effect】
As described above, according to the present invention, there is provided an electrophotographic apparatus that forms an image by static elimination, charging, latent image exposure, development, transfer, and the like,
The charging unit is a contact charging unit, and is arranged in a plurality of stages along the moving direction of the photoconductor, and the photoconductor is
A photoconductive layer made of a non-single-crystal material containing silicon as a host and containing at least a hydrogen atom and / or a halogen atom;
An upper blocking layer made of a non-single-crystal material containing silicon and carbon as base materials and containing a group 13 atom of the periodic table;
A surface layer made of a non-single-crystal material having at least carbon as a component, and the surface layer has a dynamic hardness of 4900 to 12750 N / mm. ² (500-1300kgf / mm ² )
As a result, excellent charging ability and extremely small unevenness of charging ability can be realized, and a drum can be hardly scraped, and a long life and high stability can be realized. The electrophotographic apparatus is also excellent in characteristics and can achieve extremely good characteristics at a high level simultaneously.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating an electrophotographic apparatus of the present invention.
FIG. 2 is a diagram schematically illustrating a charging unit of the present invention.
FIG. 3 is a diagram schematically illustrating a full-color electrophotographic apparatus using four photoconductors as another example of the electrophotographic apparatus of the present invention.
FIG. 4 is a schematic cross-sectional view of a photoconductor for explaining a layer configuration of the photoconductor essential for the electrophotographic apparatus of the present invention.
FIG. 5 is a diagram schematically showing one of the film deposition apparatuses that can be suitably used for producing a photosensitive member essential to the electrophotographic apparatus of the present invention. FIG. 5A is a longitudinal sectional view, and FIG. 5B is a transverse sectional view.
FIG. 6 is a diagram comparing the dependence of charging ability on process speed in three types of charging systems in Experimental Example 1 and Comparative Experimental Example 1.
FIG. 7 is a diagram comparing the dependence of uneven charging ability on process speed in three types of charging systems in Experimental Example 1 and Comparative Experimental Example 1.
FIG. 8 is a diagram comparing the relative values of the charging ability depending on the difference in the upper blocking layer in Experimental Example 2 and Comparative Experimental Example 2 with three types of charging methods.
FIG. 9 is a diagram comparing the relative values of charging ability unevenness due to the difference in the upper blocking layer in Experimental Example 2 and Comparative Experimental Example 2 with three types of charging methods.
FIG. 10 is a diagram showing a relative value of charging ability unevenness with respect to t / S by changing the upper blocking layer thickness, the charger arrangement, and the process speed in Experimental Example 5.
[Explanation of symbols]
101 Photoconductor
102 Conductive roller charger
103 Magnetic brush charger
104 developer
105 Transfer paper supply system
106 (a) Transfer charger
106 (b) Separate charger
107 Cleaning unit
108 Transport system
109 Static elimination light source
110 Halogen lamp
111 platen
112 manuscript
113 mirror
114 mirror
115 mirror
116 Lens unit
117 CCD unit
118 laser unit
119 mirror
121 cleaning blade
122 registration roller
124 fuser
201 Photoconductor
202 Conductive roller charger
203 Magnetic brush charger
204 fixed magnet
205 charging sleeve
206 Magnetic particles for charging
207 Magnetic particle regulating means (blade)
208 conductive cored bar
209 Elastic layer
210 Surface layer
211, 212 Current detector
213,214 Bias device
Pa-Pd image forming unit
1a-1d photoreceptor
2a to 2d charging unit
3a-3d image exposure apparatus
4a-4d developing unit
5a-5d cleaner
6a-6d transfer means
7 Fixing device
8 Intermediate transfer member
9 Transfer belt
10 Transfer charging means
13 Registration roller
M Recording material (paper, etc.)
401 base
402 Lower blocking layer
403 Photoconductive layer
404 Upper blocking layer
405 surface layer
406 Photoconductive layer
407 Photoconductive layer
501 Cylindrical substrate
502 Reaction vessel
503 gas inlet pipe
504 cathode electrode
505 exhaust pipe
506 Substrate support
507 High frequency power supply
508 High frequency power supply
509 Matching box
510 rotation axis
511 motor
512 gear
513 High frequency power branch
515 shield

Claims (11)

Electrostatic elimination, charging, latent image exposure, development, and an electrophotographic apparatus equipped with each means of transfer,
The charging unit is a contact charging unit, and a plurality of the charging units are arranged along a moving direction of the photoconductor,
The photoconductor,
A photoconductive layer made of a non-single-crystal material containing silicon as a host and containing at least a hydrogen atom and / or a halogen atom;
An upper blocking layer made of a non-single-crystal material containing silicon and carbon as base materials and containing a group 13 atom of the periodic table;
A surface layer made of a non-single-crystal material having at least carbon as a constituent element, wherein the dynamic hardness of the surface layer is 4900 to 12750 N / mm ² (500 to 1300 kgf / mm ² );
An electrophotographic apparatus characterized by the above-mentioned. 2. The electrophotographic apparatus according to claim 1, wherein the plurality of charging units include a conductive roller charger on the upstream side in the moving direction of the photoconductor and a magnetic brush charger on the downstream side. In the charging means having the above-described structure, the time S (s) from the time when the surface of the photoconductor passes directly below the charger on the upstream side to the time immediately below the charger on the downstream side, and the thickness t ( 3. The electrophotographic apparatus according to claim 2, wherein a relationship t / S (μm / s) with μm) is 10 or less. 4. An electrophotographic apparatus according to claim 1, wherein said development is reversal development. The ratio of carbon atoms to the sum of silicon atoms (Si) and carbon atoms (C) in the upper blocking layer, C / (Si + C), is in the range of 0.05 ≦ C / (Si + C) ≦ 0.6. 5. The electrophotographic apparatus according to any one of 1 to 4. 6. The electrophotographic apparatus according to claim 1, wherein in the upper blocking layer, the content of Group 13 atoms in the periodic table with respect to the sum of silicon atoms and carbon atoms is 100 atomic ppm or more and 30000 atomic ppm or less. 7. The electrophotographic apparatus according to claim 1, wherein said upper blocking layer has a thickness of 0.01 μm or more and 1 μm or less. The electrophotographic apparatus according to claim 1, wherein the upper blocking layer contains hydrogen atoms, and a concentration of the hydrogen atoms in the thickness direction gradually decreases toward the surface layer. 9. A composition transition region between the surface layer and the upper blocking layer, wherein a composition transition region in which the composition of silicon atoms and carbon atoms changes continuously in the film thickness direction at a value between the two layers. 2. The electrophotographic apparatus according to claim 1. The said surface layer contains at least silicon and hydrogen, The ratio C / (Si + C) of the carbon atom with respect to the sum of a silicon atom (Si) and a carbon atom (C) is 0.7 or more. An electrophotographic apparatus according to any one of the above. The electrophotographic apparatus according to claim 1, wherein the surface layer is made of an amorphous carbon film containing at least hydrogen.

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