JP3530877B2 - Developing device - Google Patents
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- JP3530877B2 JP3530877B2 JP12528997A JP12528997A JP3530877B2 JP 3530877 B2 JP3530877 B2 JP 3530877B2 JP 12528997 A JP12528997 A JP 12528997A JP 12528997 A JP12528997 A JP 12528997A JP 3530877 B2 JP3530877 B2 JP 3530877B2
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Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】この発明は、複写機やプリン
ター等の画像形成装置において、像担持体に形成された
静電潜像を現像するのに使用する現像装置に係り、特
に、静電潜像が形成される像担持体と所要間隔を介して
対向するように設けられた現像剤担持体の表面に現像剤
を保持させ、この現像剤担持体によって現像剤を像担持
体と対向する現像領域に導くと共に、この現像剤担持体
に交番電圧を印加させて現像を行なうようになった現像
装置に関するものである。
【０００２】
【従来の技術】従来より、複写機やプリンター等の画像
形成装置においては、像担持体に形成された静電潜像を
現像するのに様々な現像装置が使用されており、このよ
うな現像装置としては、トナーとキャリアとを含む現像
剤を使用した二成分現像方式の現像装置の他に、キャリ
アを用いずに現像剤としてトナーだけを使用した一成分
現像方式の現像装置が知られていた。
【０００３】また、このような一成分現像方式の現像装
置においては、現像剤担持体の表面に保持された現像剤
を静電潜像が形成された像担持体の表面に接触させて現
像を行なう接触式の現像装置の他に、現像剤担持体を像
担持体と所要間隔を介して対向するように設け、この現
像剤担持体に交番電圧を印加して、現像剤担持体と像担
持体との間に交番電界を作用させ、現像剤担持体の表面
に保持された現像剤を静電潜像が形成された像担持体に
供給して現像を行なうようにした非接触式の現像装置が
知られている。
【０００４】また、このように像担持体と所要間隔を介
して対向するように現像剤担持体を設けた非接触式の現
像装置において、形成される画像における耐刷時の濃度
変化や現像ムラを防止するため、特公昭６３−５５７０
９号公報に示されるように、現像剤担持体の表面に絶縁
層を設けたものも提案されている。
【０００５】しかし、上記のように現像剤担持体を像担
持体と所要間隔を介して対向するように設けた非接触式
の現像装置を用いて、微小ドットで作られる網点画像を
現像するようにした場合、この網点画像がかすれてしま
い、特に、低画像濃度領域において良好な階調性を得る
ことが困難になるという問題があった。
【０００６】そこで、このような問題を改善するため、
現像剤担持体と像担持体との間に作用させる交番電界を
強くして現像効率を向上させることが検討されたが、こ
のように交番電界を強くすると、像担持体の表面におけ
る電荷がリークされて、非画像部分にもトナーが付着し
て形成される画像にノイズが生じたり、形成される画像
の濃度が低下したりする等の問題があった。
【０００７】
【発明が解決しようとする課題】この発明は、静電潜像
が形成される像担持体と所要間隔を介して対向するよう
に設けられた現像剤担持体の表面に現像剤を保持させ、
この現像剤担持体によって現像剤を像担持体と対向する
現像領域に導くと共に、この現像剤担持体に交番電圧を
印加して現像を行なうようになった現像装置における上
記のような様々な問題を解決することを課題とするもの
である。
【０００８】すなわち、この発明においては、上記のよ
うな現像装置により微小ドットで作られる網点画像を現
像する場合に、現像剤担持体と像担持体の間に作用させ
る交番電界を強くしなくても、形成される網点画像がか
すれるということがなく、低画像濃度領域においても良
好な階調性が得られ、また像担持体の表面における電荷
がリークされて非画像部分にトナーが付着したり、形成
される画像の濃度が低下するということもなく、良好な
画像が得られるようにすることを課題とするものであ
る。
【０００９】
【課題を解決するための手段】この発明の現像装置にお
いては、上記のような課題を解決するため、静電潜像が
形成される像担持体と所要間隔を介して対向するように
設けられた現像剤担持体の表面に現像剤を保持させ、こ
の現像剤担持体によって現像剤を像担持体と対向する現
像領域に導くと共に、この現像剤担持体に交番電圧を印
加させて現像を行なう現像装置において、上記の現像剤
担持体として、導電性基体の表面に、層厚が４０〜１２
０μｍの範囲になった体積固有抵抗値が１０ 10 Ω・ｃｍ
以上の高抵抗層を設けたものを用い、この現像剤担持体
に作用させる上記の交番電圧のピークピーク値Ｖｐｐ
（ｋＶ）と、この現像剤担持体における導電性基体と上
記の像担持体とが対向する間隔Ｄ（ｍｍ）とが、３ｋＶ
／ｍｍ≦Ｖｐｐ／Ｄ≦８ｋＶ／ｍｍの関係を満たすよう
にした。
【００１０】ここで、この発明における現像装置のよう
に、導電性基体の表面に高抵抗層が設けられた現像剤担
持体を用い、この現像剤担持体により現像剤を像担持体
と対向する現像領域に導くと共に、この現像剤担持体に
交番電圧を印加させて、現像剤担持体と像担持体との間
に交番電界を作用させる場合、この交番電界が現像剤担
持体における導電性基体と像担持体との間において作用
し、交番電界の強さがこの高抵抗層により制御されるよ
うになる。
【００１１】そして、この発明における現像装置のよう
に、現像剤担持体における高抵抗層の厚みを上記のよう
に４０〜１２０μｍの範囲にすると共に、この現像剤担
持体に印加させる交番電圧のピークピーク値Ｖｐｐと、
この現像剤担持体における導電性基体と像担持体との対
向する間隔Ｄとが、３ｋＶ／ｍｍ≦Ｖｐｐ／Ｄ≦８ｋＶ
／ｍｍの関係を満たすようにすると、像担持体の表面に
おける電荷がリークされて形成される画像にノイズ等が
発生するということがなく、現像性能が向上されて、微
小ドットで作られる網点画像であっても適切に現像さ
れ、階調性に優れた良好な画像が得られるようになる。
【００１２】ここで、上記の現像剤担持体において、導
電性基体の表面に設ける高抵抗層の層厚が４０μｍより
薄くなったり、上記のＶｐｐ／Ｄの値が３ｋＶ／ｍｍよ
りも小さくなると、この現像装置における現像効率が低
下して、十分な画像濃度を有する画像が得られなくなる
一方、高抵抗層の厚みが１２０μｍより厚くなると、現
像剤担持体における導電性基体と像担持体との対向する
間隔Ｄを一定にした場合において、現像剤担持体の表面
に保持された現像剤が像担持体の表面に近づき、また上
記のＶｐｐ／Ｄの値が８ｋＶ／ｍｍよりも高くなると、
像担持体の表面における電荷がこの交番電界の作用によ
ってリークされ、何れの場合においても形成される画像
にノイズが発生しやすくなる。
【００１３】また、上記の現像剤担持体において、その
導電性基体の表面に設ける高抵抗層の抵抗値が低いと、
この高抵抗層によって現像剤担持体と像担持体との間に
作用する交番電界を制御することができなくなるため、
この高抵抗層としては、体積固有抵抗値が１０10Ω・ｃ
ｍ以上のものを用いるようにする。
【００１４】
【発明の実施の形態】以下、この発明の実施形態に係る
現像装置を添付図面に基づいて具体的に説明する。
【００１５】この実施形態においては、図１に示すよう
に、円筒状になった導電性支持体１ａの表面に感光層１
ｂが形成された感光体ドラム１からなる像担持体１を用
い、この像担持体１の表面を帯電装置（図示せず）によ
って帯電させた後、この像担持体１の表面に適当な露光
装置（図示せず）から光を照射させて、この像担持体１
の表面に画像情報に応じた静電潜像を形成するようにし
ている。
【００１６】そして、この実施形態における現像装置に
おいては、同図に示すように、現像剤担持体１１とし
て、導電性の回転軸１１ａの周囲に導電性の弾性層１１
ｂが設けられてなる導電性基体１１ｃの表面に高抵抗層
１１ｄが形成されたものを用い、この現像剤担持体１１
を像担持体１と所要間隔を介して対向するように設け、
この現像剤担持体１１における導電性基体１１ｃと像担
持体１とが適当な間隔Ｄで対向するようにしている。
【００１７】ここで、上記の回転軸１１ａの周囲に設け
る導電層１１ｂを構成する材料としては、例えば、エチ
レン−プロピレン−ジエン−メチレン共重合ゴム（ＥＰ
ＤＭ）、シリコンゴム、ウレタンゴム等のゴム材料が用
いられ、これにケッチェンブラック、アセチレンブラッ
ク、ファーネスブラック等のカーボンブラックを分散さ
せて体積固有抵抗値を１０6 Ω・ｃｍ以下にしたものが
一般に用いられる。
【００１８】一方、この導電層１１ｂの表面に設ける高
抵抗層１１ｄを構成する材料としては、一般にナイロン
やウレタン等の樹脂材料で、体積固有抵抗値が１０10Ω
・ｃｍ以上のものが用いられ、またこの高抵抗層１１ｄ
の層厚を４０〜１２０μｍ、好ましくは５０〜１００μ
ｍの範囲になるようにする。
【００１９】そして、この現像剤担持体１１が設けられ
た現像装置における装置本体１０の収容部１０ａ内に現
像剤（トナー）１２を収容させ、この現像剤１２を回転
する送り羽根１３によって現像剤担持体１１に送り、こ
の現像剤１２を現像剤担持体１１の表面に保持させ、こ
の現像剤担持体１１の回転により現像剤１２を像担持体
１と対向する現像領域に搬送するようにしている。
【００２０】そして、このように現像剤担持体１１によ
り現像剤１２を像担持体１と対向する現像領域に搬送す
る途中において、この現像剤担持体１１の表面に装置本
体１０内に設けられた規制部材１４を圧接させ、この規
制部材１４により現像剤担持体１１によって搬送される
現像剤１２の量を規制すると共に、この現像剤１２を摩
擦帯電させるようにしている。
【００２１】ここで、上記の規制部材１４としては、例
えば、ステンレスやリン青銅で構成され、厚さ０．０８
〜０．２ｍｍの範囲になった板ばねが用いられる。
【００２２】また、このように現像剤担持体１１の表面
に規制部材１４を圧接させて現像剤担持体１１によって
搬送される現像剤１２の量を規制する場合、上記の現像
剤担持体１１における導電性基体１１ｃの少なくとも表
面をゴム硬度が１０〜７０度で、伸びが４００〜１２０
０％の導電性の弾性材料で構成することが好ましい。
【００２３】ここで、このように現像剤担持体１１にお
ける導電性基体１１ｃの少なくとも表面を、ゴム硬度が
１０〜７０度で、伸びが４００〜１２００％の導電性の
弾性材料で構成すると、この現像剤担持体１１によって
搬送される現像剤１２の量を規制部材１４によって規制
する際に、この現像剤担持体１１の表面が変形して現像
剤１２に加わる負荷が軽減されて、現像剤１２の割れに
よる微粉の発生が抑制され、現像剤１２の微粉が現像剤
担持体１１の表面等に融着して形成される画像に濃度ム
ラが生じるということが少なくなるためである。なお、
上記のゴム硬度及び伸びは、ＪＩＳ Ｋ ６３０１に従
って測定した値である。
【００２４】そして、上記のように規制部材１４により
規制されて摩擦帯電された現像剤１２を現像剤担持体１
１によって像担持体１と対向する現像領域に搬送させる
と共に、この現像剤担持体１１に電源１５から直流電圧
に交流電圧を重畳させた現像バイアス電圧を印加させ
て、この現像剤担持体１１における導電性基体１１ｃと
像担持体１との間に直流電界に交番電界が重畳された電
界を作用させ、これにより現像剤担持体１１の表面に保
持された現像剤１２を像担持体１に形成された静電潜像
に供給して現像を行なうようになっている。
【００２５】ここで、上記のように電源１５から直流電
圧と共に交流電圧を印加させるにあたり、この交流電圧
のピークピーク値Ｖｐｐを、この現像剤担持体１１にお
ける導電性基体１１ｃと像担持体１とが対向する間隔Ｄ
で割った値、すなわち現像剤担持体１１における導電性
基体１１ｃと像担持体１との間に作用する交番電界の強
さ（Ｖｐｐ／Ｄ）が３〜８ｋＶ／ｍｍの範囲になるよう
にしている。
【００２６】ここで、この実施形態における現像装置に
おいて、上記の現像剤担持体１１に対して電源１５から
作用させる交流電圧のピークピーク値Ｖｐｐ及び現像剤
担持体１１に設ける高抵抗層１１ｄの層厚を変更させた
実験を行ない、これらが形成される画像に及ぼす影響を
調べた。
【００２７】ここで、現像剤担持体１１としては、ステ
ンレス製の回転軸１１ａの周囲に体積固有抵抗が１０5
Ω・ｃｍのＥＰＤＭからなる導電層１１ｂが設けられた
導電性基体１１ｃの上に、体積固有抵抗が７×１０10Ω
・ｃｍのウレタンで構成された高抵抗層１１ｄを設け、
この高抵抗層１１ｄの層厚が８０μｍと、６μｍとにな
った２種類の現像剤担持体１１を用いるようにした。
【００２８】そして、上記の像担持体１を帯電させてそ
の初期表面電位を−７００Ｖにし、この像担持体１に対
して露光を行ない露光された部分の表面電位Ｖｉｒが−
５０Ｖになるようにする一方、この像担持体１と各現像
剤担持体１１における導電性基体１１ｃとが対向する間
隔Ｄを２．５ｍｍにし、各現像剤担持体１１に対して上
記の電源１５から−１５０Ｖの直流電圧と周波数が２ｋ
Ｈｚの交流電圧を作用させるようにした。
【００２９】そして、上記の電源１５から各現像剤担持
体１１に印加させる交流電圧のピークピーク値Ｖｐｐを
変化させ、各現像剤担持体１１における導電性基体１１
ｃと像担持体１との間に作用する交番電界の強さ（Ｖｐ
ｐ／Ｄ）を変更させてそれぞれ現像を行ない、形成され
た画像における透過濃度を測定し、その結果を図２に示
した。なお、この図２においては、高抵抗層１１ｄの層
厚が８０μｍになった現像剤担持体１１を用いた場合の
結果を○と実線で、高抵抗層１１ｄの層厚が６μｍにな
った現像剤担持体１１を用いた場合の結果を●と破線で
示した。
【００３０】この結果、高抵抗層１１ｄの層厚を８０μ
ｍにした現像剤担持体１１を用いて現像を行なった場
合、上記のＶｐｐ／Ｄの値が３〜８ｋＶ／ｍｍの範囲に
おいては十分な画像濃度を有する画像が得られるのに対
して、このＶｐｐ／Ｄの値が３ｋＶ／ｍｍよりも低い
と、十分な透過濃度を有する画像が得られず、一方この
Ｖｐｐ／Ｄの値が８ｋＶ／ｍｍよりも高いと、像担持体
１の表面における電荷がリークされて非画像部分にも現
像剤１２が付着して形成される画像にノイズが生じた。
【００３１】また、高抵抗層１１ｄの層厚が６μｍにな
った現像剤担持体１１を用いて現像を行なった場合、十
分な透過濃度を有する画像を得るためには上記のＶｐｐ
／Ｄの値を７ｋＶ／ｍｍ以上にすることが必要となり、
またこのＶｐｐ／Ｄの値が８ｋＶ／ｍｍを越えると、上
記の場合と同様にリークが生じて非画像部分にも現像剤
１２が付着してしまい、十分な画像濃度を有すると共に
ノイズ等の発生のない良好な画像を得ることが困難であ
った。
【００３２】次に、現像剤担持体１１として、上記の高
抵抗層１１ｄの層厚が６μｍ、４０μｍ、８０μｍにな
った各現像剤担持体１１を用い、上記の交番電界の強さ
（Ｖｐｐ／Ｄ）を６ｋＶ／ｍｍに設定する一方、像担持
体１において露光された部分の表面電位Ｖｉｒと上記の
電源１５から現像剤担持体１１に印加させる直流電圧Ｖ
ｂとの差（Ｖｉｒ−Ｖｂ）を変化させてそれぞれ現像を
行ない、形成された画像における透過濃度を求め、その
結果を図３に示した。なお、この図３においては、高抵
抗層１１ｄの層厚が８０μｍになった現像剤担持体１１
を用いた場合の結果を○と実線で、高抵抗層１１ｄの層
厚が４０μｍになった現像剤担持体１１を用いた場合の
結果を□と実線で、高抵抗層１１ｄの層厚が６μｍにな
った現像剤担持体１１を用いた場合の結果を●と破線で
示した。
【００３３】この結果、現像剤担持体１１に設ける高抵
抗層１１ｄの層厚が厚くなるに従って現像性能が向上
し、露光された部分の表面電位Ｖｉｒと現像剤担持体１
１に印加させる直流電圧Ｖｂとの差（Ｖｉｒ−Ｖｂ）が
少ない場合であっても、十分な画像濃度を有する画像が
得られ、網点画像の再現性も良くなった。
【００３４】また、上記の現像剤担持体１１における高
抵抗層１１ｄの層厚を６μｍ、４０μｍ、８０μｍ、１
２０μｍ、１６０μｍにした各現像剤担持体１１を用
い、上記の像担持体１における初期表面電位を−７００
Ｖ、電源１５から各現像剤担持体１１に印加させる直流
電圧Ｖｂをそれぞれ−１５０Ｖにし、また現像剤担持体
１１における導電性基体１１ｃと像担持体１との間に作
用する交番電界の強さＶｐｐ／Ｄを６ｋＶ／ｍｍにして
それぞれ現像を行ない、非画像部分における透過濃度を
測定すると共に、形成された各画像におけるかぶりの評
価を行ない、その結果を下記の表１に示した。なお、か
ぶりについては、形成された各画像を目視により評価
し、かぶりが全く発生していなかった場合を○、かぶり
が若干発生したが実用上問題がない場合を△、かぶりが
発生して実用上問題がある場合を×で示した。
【００３５】
【表１】
【００３６】この結果、表面に設ける高抵抗層１１ｄの
層厚が１２０μｍ以下になった各現像剤担持体１１を用
いた場合には、形成される画像にかぶりが生じなかった
が、表面に設ける高抵抗層１１ｄの層厚が１６０μｍに
なった現像剤担持体１１を用いた場合には、形成される
画像にかぶりが生じた。
【００３７】なお、この実施形態における現像装置にお
いては、現像剤担持体１１として、上記のように導電性
の回転軸１１ａの周囲に導電性の弾性層１１ｂが設けら
れた導電性基体１１ｃの表面に高抵抗層１１ｄが形成さ
れたものを用いるようにしたが、使用する現像剤担持体
１１はこのような構成のものに限定されず、例えば、図
４に示すように、ステンレス等の導電性材料で円筒状に
形成された導電性基体１１ｃの表面に上記のような高抵
抗層１１ｄを設けたものを用いることも可能である。
【００３８】次に、この発明の実施例に係る現像装置を
用いた場合に、網点画像の再現性に優れると共に形成さ
れる画像にノイズ等が発生するということがなく、良好
な画像が得られることを明らかにする。
【００３９】（実施例１）この実施例においては、図１
に示した現像装置において、上記の現像剤担持体１１と
して、ステンレス製の回転軸１１ａの周囲に体積固有抵
抗値が１０5 Ω・ｃｍのＥＰＤＭで構成された導電層１
１ｂを設けた導電性基体１１ｃの表面に、体積固有抵抗
値が２×１０14Ω・ｃｍのナイロンを用いて層厚が４０
μｍになった高抵抗層１１ｄを設けたものを用いた。
【００４０】そして、この現像剤担持体１１における導
電性基体１１ｃと像担持体１とが対向する間隔Ｄを０．
２ｍｍになるようにセットし、上記の像担持体１を初期
表面電位が−７００Ｖになるように帯電させ、適当な露
光手段からこの像担持体１に対して網点面積率を段階的
に異ならせた画像に対応する露光を行ない、その露光部
分における表面電位が−５０Ｖになるようにし、上記の
電源１５から現像剤担持体１１に対して−１８０Ｖの直
流電圧と、周波数が５００Ｈｚでピークピーク値Ｖｐｐ
が１．５ｋＶの交流電圧とが重畳された現像バイアス電
圧を印加させ、現像剤担持体１１の導電性基体１１ｃと
像担持体１との間に作用する交番電界の強さＶｐｐ／Ｄ
を７．５ｋＶ／ｍｍにして、網点面積率を段階的に異な
らせた画像を現像した。
【００４１】この結果、この実施例の現像装置を用いて
網点面積率を段階的に異ならせた網点画像を現像する
と、階調性に優れると共にリークによるノイズの発生も
ない良好な画像が得られた。
【００４２】（実施例２）この実施例においては、上記
の図４に示した現像装置において、上記の現像剤担持体
１１として、ステンレス製の中空パイプからなる導電性
基体１１ｃの表面に、体積固有抵抗値が７×１０10Ω・
ｃｍのウレタンを用いて層厚が１００μｍになった高抵
抗層１１ｄを設けたものを用いた。
【００４３】そして、この現像剤担持体１１における導
電性基体１１ｃと像担持体１とが対向する間隔Ｄを０．
４５ｍｍになるようにセットし、上記の像担持体１を初
期表面電位が−８００Ｖになるように帯電させ、適当な
露光手段からこの像担持体１に対して網点面積率を段階
的に異ならせた画像に対応する露光を行ない、その露光
部分における表面電位が−７０Ｖになるようにし、上記
の電源１５から現像剤担持体１１に対して−２００Ｖの
直流電圧と、周波数が２ｋＨｚでピークピーク値Ｖｐｐ
が２ｋＶの交流電圧とが重畳された現像バイアス電圧を
印加し、現像剤担持体１１の導電性基体１１ｃと像担持
体１との間に作用する交番電界の強さＶｐｐ／Ｄを約
４．４ｋＶ／ｍｍにして、網点面積率を段階的に異なら
せた画像を現像した。
【００４４】この結果、この実施例の現像装置を用い網
点面積率を段階的に異ならせた網点画像を現像したた場
合も、上記の実施例１の場合と同様に、階調性に優れる
と共にリークによるノイズの発生もない良好な画像が得
られた。
【００４５】次に、図１に示した上記の実施形態におけ
る現像装置において、現像剤担持体１１の表面に規制部
材１４を圧接させて現像剤担持体１１によって搬送され
る現像剤１２の量を規制するにあたり、この現像剤担持
体１１における上記の導電層１１ｂの種類を変更させた
実験を行なった。
【００４６】ここで、この実験においては、現像剤担持
体１１として、上記の実施例１において使用した現像剤
担持体１１における導電層１１ｂの材料だけを変更さ
せ、下記の表１に示すように、実験例１においては、前
記のゴム硬度が４４度，伸びが７１０％、体積固有抵抗
値が８×１０5 Ω・ｃｍになったスチレン系エラストマ
ーを、実験例２においては、ゴム硬度が７７度、伸びが
８５０％、体積固有抵抗値が1×１０5 Ω・ｃｍになっ
たスチレン系エラストマーを、実験例３においては、ゴ
ム硬度が６８度、伸びが９８０％、体積固有抵抗値が２
×１０6 Ω・ｃｍになったウレタンゴムを、実験例４に
おいては、ゴム硬度が５０度、伸びが２９０％、体積固
有抵抗値が1×１０5 Ω・ｃｍになったシリコンゴムを
用いてそれぞれ導電層１１ｂを形成した。
【００４７】そして、実験例１〜４においては、上記の
ように導電層１１ｂを構成する材料を変更させた各現像
剤担持体１１を用いてそれぞれ１万枚の耐刷試験を行な
い、形成された画像における濃度ムラの評価を行ない、
その結果を下記の表１に合わせて示した。なお、１万枚
の耐刷試験後における画像の濃度ムラを評価するにあた
っては、濃度ムラがなく良好な画像が得られた場合を
○、筋状の濃度ムラが生じた場合を×で示した。
【００４８】
【表２】【００４９】この結果、上記の現像剤担持体１１におい
て、導電性の回転軸１１ａの周囲に導電性の導電層１１
ｂを設けるにあたり、ゴム硬度が１０〜７０度、伸びが
４００〜１２００％の範囲になった導電層１１ｂを設け
た実験例１，３のものにおいては、上記のようにこの現
像剤担持体１１の表面における現像剤１２の量を規制部
材１５により規制する場合に、現像剤１２が割れて現像
剤１２の微粉が現像剤担持体１１の表面等に融着すると
いうことが抑制され、形成された画像に濃度ムラが発生
しなかったのに対して、ゴム硬度が７７度と硬い導電層
１１ｂを設けた実験例２のものや、伸びが２９０％と少
ない導電層１１ｂを設けた実験例４のものにおいては、
現像剤担持体１１の表面における現像剤１２の量を規制
部材１５により規制する場合に、現像剤１２が割れて現
像剤１２の微粉が現像剤担持体１１の表面等に融着し、
形成された画像に筋状の濃度ムラが発生していた。
【００５０】
【発明の効果】以上詳述したように、この発明における
現像装置においては、像担持体と所要間隔を介して対向
するように設けられる現像剤担持体として、導電性基体
の表面に、層厚が４０〜１２０μｍの範囲になった体積
固有抵抗値が１０ 10 Ω・ｃｍ以上の高抵抗層が設けられ
たものを用い、この現像剤担持体に交番電圧を印加させ
て像担持体に形成された静電潜像を現像するにあたり、
現像剤担持体に印加させる交番電圧のピークピーク値Ｖ
ｐｐ（ｋＶ）と、この現像剤担持体における導電性基体
と上記の像担持体とが対向する間隔Ｄ（ｍｍ）とが、３
ｋＶ／ｍｍ≦Ｖｐｐ／Ｄ≦８ｋＶ／ｍｍの関係を満たす
ようにしたため、現像剤担持体と像担持体との間に交番
電界を作用する交番電界の強さがこの高抵抗層により制
御され、像担持体の表面における電荷がリークされて形
成される画像にノイズ等が発生するということがなく、
現像性能が向上されて、微小ドットで作られる網点画像
であっても適切に現像され、階調性に優れた良好な画像
が得られるようになった。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for developing an electrostatic latent image formed on an image carrier in an image forming apparatus such as a copying machine or a printer. According to the developing device, in particular, the developer is held on the surface of a developer carrier provided so as to be opposed to an image carrier on which an electrostatic latent image is formed with a required interval, and the developer carrier The present invention relates to a developing device in which a developer is guided to a development area facing an image carrier and an alternating voltage is applied to the developer carrier to perform development. 2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, various developing devices have been used to develop an electrostatic latent image formed on an image carrier. As such a developing device, in addition to a two-component developing system using a developer containing a toner and a carrier, a one-component developing system using only a toner as a developer without using a carrier is known. Was known. Further, in such a developing device of the one-component developing system, the developer held on the surface of the developer carrier is brought into contact with the surface of the image carrier on which the electrostatic latent image is formed to perform development. In addition to the contact-type developing device, a developer carrier is provided so as to face the image carrier at a predetermined interval, and an alternating voltage is applied to the developer carrier to cause the developer carrier and the image carrier to move. Non-contact type development in which an alternating electric field is applied between the developer and the developer to supply the developer held on the surface of the developer carrier to the image carrier on which the electrostatic latent image is formed to perform development. Devices are known. Further, in a non-contact type developing device having a developer carrying member opposed to an image carrying member at a predetermined distance, a change in density and unevenness of a formed image at the time of endurance printing. In order to prevent
As disclosed in Japanese Patent Application Laid-Open No. 9-1997, there has been proposed a developer provided with an insulating layer on the surface of a developer carrier. However, a halftone image formed by minute dots is developed by using a non-contact type developing device in which the developer carrying member is provided so as to face the image carrying member at a predetermined interval as described above. In such a case, there is a problem that the halftone image is blurred, and it is difficult to obtain a good gradation characteristic particularly in a low image density region. Therefore, in order to improve such a problem,
It has been considered to improve the development efficiency by increasing the alternating electric field acting between the developer carrier and the image carrier.However, when the alternating electric field is strengthened in this way, the charge on the surface of the image carrier leaks. As a result, there is a problem that an image formed by attaching toner also to a non-image portion generates noise, a density of the formed image is reduced, and the like. SUMMARY OF THE INVENTION According to the present invention, a developer is provided on a surface of a developer carrier provided so as to be opposed to an image carrier on which an electrostatic latent image is formed at a predetermined interval. Let me hold
The above-described various problems in the developing device in which the developer is guided to the development area facing the image carrier by the developer carrier and an alternating voltage is applied to the developer carrier to perform the development. It is an object to solve the above. That is, according to the present invention, when a halftone image formed by minute dots is developed by the developing device as described above, the alternating electric field applied between the developer carrier and the image carrier is not increased. However, the formed halftone image is not blurred, good gradation can be obtained even in a low image density area, and the charge on the surface of the image carrier is leaked and toner adheres to the non-image portion. It is an object of the present invention to obtain a good image without causing the density of the formed image to decrease. In order to solve the above-mentioned problems, the developing device of the present invention is arranged so as to face an image bearing member on which an electrostatic latent image is formed with a required distance. The developer is held on the surface of the developer carrier provided in the developer carrier, and the developer is guided by the developer carrier to a development region facing the image carrier, and an alternating voltage is applied to the developer carrier. In a developing device for performing development , a layer thickness of 40 to 12 is applied on the surface of the conductive substrate as the developer carrier.
Volume resistivity value in the range of 0 μm is 10 10 Ω · cm
The above-mentioned high-resistance layer is provided, and the peak-to-peak value Vpp of the alternating voltage applied to the developer carrier is used.
(KV) and the distance D (mm) between the conductive substrate and the image carrier in the developer carrier are 3 kV.
/ Mm ≦ Vpp / D ≦ 8 kV / mm. Here, as in the developing device of the present invention, a developer carrier having a high resistance layer provided on the surface of a conductive substrate is used, and the developer is opposed to the image carrier by the developer carrier. When an alternating voltage is applied to the developer carrier and an alternating electric field is applied between the developer carrier and the image carrier, the alternating electric field is applied to the conductive substrate in the developer carrier. And the image carrier, and the strength of the alternating electric field is controlled by the high resistance layer. Further, as in the developing device of the present invention, the thickness of the high resistance layer in the developer carrier is set in the range of 40 to 120 μm as described above, and the alternating voltage applied to the developer carrier is controlled. Peak-to-peak value Vpp,
The distance D between the conductive substrate and the image carrier in the developer carrier is 3 kV / mm ≦ Vpp / D ≦ 8 kV.
/ Mm, the charge formed on the surface of the image carrier is not leaked, so that no noise or the like is generated in the formed image, the developing performance is improved, and the halftone dot formed by minute dots is improved. Even an image is appropriately developed, and a good image with excellent gradation can be obtained. Here, in the above-mentioned developer carrying member, when the layer thickness of the high resistance layer provided on the surface of the conductive substrate becomes thinner than 40 μm, or when the value of Vpp / D becomes lower than 3 kV / mm. On the other hand, while the developing efficiency in this developing device is reduced and an image having a sufficient image density cannot be obtained, when the thickness of the high resistance layer is more than 120 μm, the conductive substrate and the image carrier in the developer carrier are In the case where the distance D opposed to each other is constant, if the developer held on the surface of the developer carrier approaches the surface of the image carrier and the value of Vpp / D becomes higher than 8 kV / mm,
Electric charges on the surface of the image carrier are leaked by the action of the alternating electric field, and in any case, noise is easily generated in the formed image. In the above-mentioned developer carrying member, if the resistance value of the high resistance layer provided on the surface of the conductive substrate is low,
Because the high resistance layer makes it impossible to control the alternating electric field acting between the developer carrier and the image carrier,
The high resistivity layer has a volume resistivity of 10 10 Ω · c.
m or more . Hereinafter, a developing device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, as shown in FIG. 1, a photosensitive layer 1 is provided on the surface of a cylindrical conductive support 1a.
The surface of the image carrier 1 is charged by a charging device (not shown) using the image carrier 1 formed of the photosensitive drum 1 on which the surface of the image carrier 1 is formed. The image carrier 1 is irradiated with light from a device (not shown).
An electrostatic latent image corresponding to the image information is formed on the surface of the. In the developing device according to this embodiment, as shown in FIG. 1, a conductive elastic layer 11 is provided around a conductive rotating shaft 11a as a developer carrier 11.
b having a high resistance layer 11d formed on the surface of a conductive substrate 11c provided with
Is provided so as to face the image carrier 1 at a required interval,
The conductive substrate 11c of the developer carrier 11 and the image carrier 1 are opposed to each other at an appropriate distance D. The conductive layer 11b provided around the rotating shaft 11a is made of, for example, ethylene-propylene-diene-methylene copolymer rubber (EP).
DM), a rubber material such as silicone rubber, urethane rubber or the like is used, and a carbon black such as Ketjen black, acetylene black, furnace black or the like is dispersed in the rubber material so as to have a volume resistivity of 10 6 Ω · cm or less. Generally used. On the other hand, a material constituting the high resistance layer 11d provided on the surface of the conductive layer 11b is generally a resin material such as nylon or urethane, and has a volume resistivity of 10 10 Ω.
Cm or more, and the high resistance layer 11d
Layer thickness of 40 to 120 μm, preferably 50 to 100 μm
m. A developer (toner) 12 is accommodated in an accommodating portion 10a of the apparatus main body 10 of the developing device provided with the developer carrier 11, and the developer 12 is rotated by a feed blade 13 which rotates. The developer 12 is sent to the carrier 11, the developer 12 is held on the surface of the developer carrier 11, and the developer 12 is conveyed to a development area facing the image carrier 1 by rotation of the developer carrier 11. I have. While the developer 12 is being conveyed to the development area facing the image carrier 1 by the developer carrier 11, the developer 12 is provided in the apparatus main body 10 on the surface of the developer carrier 11. The regulating member 14 is brought into pressure contact with the regulating member 14 to regulate the amount of the developer 12 conveyed by the developer carrier 11 and to frictionally charge the developer 12. The regulating member 14 is made of, for example, stainless steel or phosphor bronze, and has a thickness of 0.08.
A leaf spring having a range of about 0.2 mm is used. When the regulating member 14 is pressed against the surface of the developer carrier 11 to regulate the amount of the developer 12 conveyed by the developer carrier 11, the amount of the developer At least the surface of the conductive substrate 11c has a rubber hardness of 10 to 70 degrees and an elongation of 400 to 120.
It is preferable to use a conductive elastic material of 0%. If at least the surface of the conductive substrate 11c in the developer carrier 11 is made of a conductive elastic material having a rubber hardness of 10 to 70 degrees and an elongation of 400 to 1200%, When the amount of the developer 12 conveyed by the developer carrier 11 is regulated by the regulating member 14, the surface of the developer carrier 11 is deformed and the load applied to the developer 12 is reduced. This is because the generation of fine powder due to cracks of the developer is suppressed, and the occurrence of density unevenness in an image formed by fusing the fine powder of the developer 12 to the surface of the developer carrier 11 or the like is reduced. In addition,
The above rubber hardness and elongation are values measured according to JIS K6301. The developer 12 regulated by the regulating member 14 and charged as described above is charged with the developer carrier 1.
1, the developer is conveyed to a developing area opposed to the image carrier 1, and a developing bias voltage in which an AC voltage is superimposed on a DC voltage is applied from a power supply 15 to the developer carrier 11 to apply the developing bias voltage to the developer carrier 11. An electric field in which an alternating electric field is superimposed on a DC electric field is applied between the conductive substrate 11c and the image carrier 1, thereby forming the developer 12 held on the surface of the developer carrier 11 on the image carrier 1. The developed electrostatic latent image is supplied and developed. Here, when the AC voltage is applied together with the DC voltage from the power supply 15 as described above, the peak-to-peak value Vpp of the AC voltage is determined by using the conductive substrate 11c and the image carrier 1 in the developer carrier 11. Is the distance D facing
, That is, the strength (Vpp / D) of the alternating electric field acting between the conductive substrate 11c and the image carrier 1 in the developer carrier 11 is in the range of 3 to 8 kV / mm. I have. Here, in the developing device in this embodiment, the peak-to-peak value Vpp of the AC voltage applied from the power supply 15 to the developer carrier 11 and the layer of the high resistance layer 11 d provided on the developer carrier 11. Experiments with varying thicknesses were performed to determine the effect of these on the formed image. The developer carrier 11 has a volume resistivity of 10 5 around a stainless steel rotating shaft 11a.
A volume resistivity is 7 × 10 10 Ω on a conductive substrate 11c provided with a conductive layer 11b made of EPDM of Ω · cm.
Providing a high resistance layer 11d made of urethane of cm.
Two types of developer carriers 11 having a high resistance layer 11d having a layer thickness of 80 μm and 6 μm were used. The image carrier 1 is charged to set its initial surface potential at -700 V, and the image carrier 1 is exposed to light, and the surface potential Vir of the exposed portion is-.
On the other hand, the distance D between the image carrier 1 and the conductive substrate 11c of each developer carrier 11 is set to 2.5 mm, and the power supply 15 is applied to each developer carrier 11. -150V DC voltage and frequency 2k
Hz AC voltage was applied. Then, the peak-to-peak value Vpp of the AC voltage applied from the power source 15 to each developer carrier 11 is changed, and the conductive substrate 11 in each developer carrier 11 is changed.
c and the intensity of the alternating electric field (Vp
(p / D) was changed and development was performed, and the transmission density in the formed image was measured. The result is shown in FIG. In FIG. 2, the results obtained when the developer carrying member 11 in which the layer thickness of the high-resistance layer 11d is 80 μm are indicated by ○ and the solid line, and the development in which the layer thickness of the high-resistance layer 11d is 6 μm. The results in the case where the agent carrier 11 was used are indicated by a black dot and a broken line. As a result, the thickness of the high resistance layer 11d is reduced to 80 μm.
When the development is performed using the developer carrier 11 having an m of m, an image having a sufficient image density is obtained when the value of Vpp / D is in the range of 3 to 8 kV / mm. If the value of Vpp / D is lower than 3 kV / mm, an image having a sufficient transmission density cannot be obtained, while if the value of Vpp / D is higher than 8 kV / mm, the charge on the surface of the image carrier 1 Was leaked, and noise was generated in an image formed by the developer 12 adhering to the non-image portion. When the development is performed using the developer carrier 11 in which the layer thickness of the high resistance layer 11d is 6 μm, the above Vpp is required to obtain an image having a sufficient transmission density.
/ D value needs to be 7 kV / mm or more,
If the value of Vpp / D exceeds 8 kV / mm, a leak occurs as in the above case, and the developer 12 adheres to the non-image portion, so that a sufficient image density is obtained and noise is generated. It was difficult to obtain a good image without the image. Next, as the developer carrying member 11, each of the high carrying layers 11d having the thickness of 6 μm, 40 μm and 80 μm was used, and the intensity of the alternating electric field (Vpp / D) is set to 6 kV / mm, while the surface potential Vir of the exposed portion of the image carrier 1 and the DC voltage V applied from the power supply 15 to the developer carrier 11 are set.
The development was carried out by changing the difference (Vir-Vb) from b, and the transmission density in the formed image was obtained. The result is shown in FIG. In FIG. 3, the developer carrier 11 in which the thickness of the high resistance layer 11d is 80 μm is shown.
Is a solid line and the result when using the developer carrier 11 in which the layer thickness of the high resistance layer 11d is 40 μm is □ and a solid line, and the layer thickness of the high resistance layer 11d is 6 μm. The results obtained when the developer carrier 11 obtained in the above manner was used are indicated by a black circle and a broken line. As a result, the developing performance is improved as the layer thickness of the high resistance layer 11d provided on the developer carrier 11 increases, and the surface potential Vir of the exposed portion and the developer carrier 1 are improved.
Even when the difference (Vir−Vb) from the DC voltage Vb applied to 1 was small, an image having a sufficient image density was obtained, and the reproducibility of a halftone image was improved. The thickness of the high resistance layer 11d in the developer carrier 11 is set to 6 μm, 40 μm, 80 μm, 1 μm.
Using the developer carriers 11 of 20 μm and 160 μm, the initial surface potential of the image carrier 1 was -700.
V, the DC voltage Vb applied from the power supply 15 to each developer carrier 11 is set to -150 V, and the intensity of an alternating electric field acting between the conductive substrate 11c and the image carrier 1 in the developer carrier 11 Each development was carried out at Vpp / D of 6 kV / mm, the transmission density in the non-image portion was measured, and the fogging of each formed image was evaluated. The results are shown in Table 1 below. Regarding fogging, each formed image was evaluated by visual observation, and 場合 indicates that no fogging occurred, Δ indicates that some fogging occurred but there was no practical problem, The case where there is an above problem is indicated by x. [Table 1] As a result, when each of the developer carrying members 11 in which the thickness of the high resistance layer 11d provided on the surface was 120 μm or less was used, no fogging occurred on the formed image, but When the developer supporting member 11 in which the thickness of the provided high resistance layer 11d was 160 μm was used, fogging occurred in the formed image. In the developing device according to this embodiment, as the developer carrier 11, the surface of the conductive substrate 11c having the conductive elastic layer 11b provided around the conductive rotating shaft 11a as described above. The developer carrier 11 used is not limited to such a configuration. For example, as shown in FIG. 4, a conductive material such as stainless steel may be used. It is also possible to use a material in which a high-resistance layer 11d as described above is provided on the surface of a conductive substrate 11c formed of a material in a cylindrical shape. Next, when the developing device according to the embodiment of the present invention is used, the reproducibility of the halftone dot image is excellent, and no noise or the like is generated in the formed image. Clarify that (Embodiment 1) In this embodiment, FIG.
In the developing device shown in (1), the conductive layer 1 made of EPDM having a volume specific resistance of 10 5 Ω · cm around a stainless steel rotating shaft 11a is used as the developer carrier 11 described above.
On the surface of the conductive substrate 11c provided with 1b, nylon having a volume resistivity of 2 × 10 14 Ω · cm and a layer thickness of 40
The one provided with a high resistance layer 11d of μm was used. The distance D between the conductive substrate 11c and the image carrier 1 in the developer carrier 11 is set to be 0.
The image carrier 1 is charged so as to have an initial surface potential of -700 V. If the halftone dot area ratio of the image carrier 1 with respect to the image carrier 1 is changed stepwise by appropriate exposure means, Exposure corresponding to the exposed image is performed so that the surface potential at the exposed portion becomes −50 V, a DC voltage of −180 V from the power supply 15 to the developer carrier 11, and a peak-to-peak frequency of 500 Hz. Value Vpp
Is applied with a developing bias voltage on which an AC voltage of 1.5 kV is superimposed, and the intensity of an alternating electric field acting between the conductive substrate 11c of the developer carrier 11 and the image carrier 1 is Vpp / D.
Was adjusted to 7.5 kV / mm to develop an image in which the halftone dot area ratio was varied stepwise. As a result, when the halftone image having the halftone dot area ratio stepwise changed using the developing apparatus of this embodiment is developed, a good image having excellent gradation and no noise due to leakage can be obtained. Obtained. (Embodiment 2) In this embodiment, in the developing device shown in FIG. 4 described above, as the developer carrier 11, the volume of the conductive substrate 11c made of a stainless steel hollow pipe was The specific resistance value is 7 × 10 10 Ω
A layer provided with a high-resistance layer 11d having a layer thickness of 100 μm using urethane of cm. The distance D between the conductive substrate 11c and the image carrier 1 in the developer carrier 11 is set to 0.
The image carrier 1 is charged so as to have an initial surface potential of -800 V. Exposure corresponding to the exposed image is performed so that the surface potential at the exposed portion becomes -70 V, a DC voltage of -200 V from the power supply 15 to the developer carrier 11 and a peak-to-peak frequency of 2 kHz. Value Vpp
Apply a developing bias voltage on which an AC voltage of 2 kV is superimposed, and reduce the intensity Vpp / D of the alternating electric field acting between the conductive substrate 11c of the developer carrier 11 and the image carrier 1 to about 4. At 4 kV / mm, an image was developed in which the dot area ratio was changed stepwise. As a result, when a halftone image in which the halftone dot area ratio is changed stepwise by using the developing apparatus of this embodiment is developed, the gradation property is improved as in the case of the first embodiment. A good image which was excellent and free from noise due to leak was obtained. Next, in the developing device according to the above-described embodiment shown in FIG. 1, the regulating member 14 is pressed against the surface of the developer carrier 11 so that the amount of the developer 12 conveyed by the developer carrier 11 is determined. For the regulation, an experiment was conducted in which the type of the conductive layer 11b in the developer carrier 11 was changed. In this experiment, only the material of the conductive layer 11b of the developer carrier 11 used in Example 1 was changed as shown in Table 1 below. In Experimental Example 1, a styrene elastomer having a rubber hardness of 44 degrees, an elongation of 710%, and a volume resistivity of 8 × 10 5 Ω · cm was used. In Experimental Example 2, a rubber hardness of 77 was used. A styrene-based elastomer having a degree and elongation of 850% and a volume resistivity of 1 × 10 5 Ω · cm was obtained. In Experimental Example 3, the rubber hardness was 68 degrees, the elongation was 980%, and the volume resistivity was 2%.
In Example 4, a urethane rubber having a density of × 10 6 Ω · cm was used, and a silicone rubber having a rubber hardness of 50 degrees, an elongation of 290%, and a volume resistivity of 1 × 10 5 Ω · cm was used. The respective conductive layers 11b were formed. In each of Experimental Examples 1 to 4, a printing durability test of 10,000 sheets was performed by using each of the developer carriers 11 in which the material of the conductive layer 11b was changed as described above. The density unevenness of the image
The results are shown in Table 1 below. In evaluating the density unevenness of the image after the 10,000-sheet printing test, a case where a good image was obtained without the density unevenness was indicated by “、”, and a case where streak-like density unevenness occurred was indicated by “×”. . [Table 2] As a result, in the developer carrier 11, the conductive layer 11 is formed around the conductive rotating shaft 11a.
In the case of Experimental Examples 1 and 3 provided with the conductive layer 11b having a rubber hardness of 10 to 70 degrees and an elongation in the range of 400 to 1200%, the developer carrier 11 is provided as described above. When the amount of the developer 12 on the surface of the developer is regulated by the regulating member 15, it is suppressed that the developer 12 is broken and the fine powder of the developer 12 is fused to the surface of the developer carrier 11 or the like. In contrast to the example in which the density unevenness did not occur in the image, the experimental example 2 in which the hard conductive layer 11b having a rubber hardness of 77 degrees was provided and the experimental example 4 in which the conductive layer 11b having a small elongation of 290% were provided In the
When the amount of the developer 12 on the surface of the developer carrier 11 is regulated by the regulating member 15, the developer 12 is broken, and fine powder of the developer 12 is fused to the surface of the developer carrier 11,
Streaky density unevenness occurred in the formed image. As described above in detail, in the developing device according to the present invention, the developer carrying member provided on the surface of the conductive substrate is provided so as to face the image carrying member at a required interval. , Volume with layer thickness in the range of 40-120 μm
In developing an electrostatic latent image formed on the image carrier by applying an alternating voltage to the developer carrier using a material provided with a high resistance layer having a specific resistance of 10 10 Ωcm or more ,
Peak-to-peak value V of the alternating voltage applied to the developer carrier
pp (kV) and the distance D (mm) between the conductive substrate and the image carrier in the developer carrier are 3
Since the relationship of kV / mm ≦ Vpp / D ≦ 8 kV / mm was satisfied, the intensity of the alternating electric field acting between the developer carrier and the image carrier was controlled by the high resistance layer, There is no occurrence of noise or the like in an image formed by leaking charges on the surface of the image carrier,
The development performance has been improved, so that even a halftone image formed by minute dots is appropriately developed, and a good image with excellent gradation can be obtained.
【図面の簡単な説明】
【図１】この発明の実施形態に係る現像装置の概略断面
図である。
【図２】上記の実施形態における現像装置において、高
抵抗層の層厚が８０μｍと６μｍの各現像剤担持体を用
い、各現像剤担持体における導電性基体と像担持体との
間に作用させる交番電界の強さ（Ｖｐｐ／Ｄ）を変更さ
せて現像を行なった場合において、形成された画像にお
ける透過濃度と交番電界の強さ（Ｖｐｐ／Ｄ）との関係
を示した図である。
【図３】上記の実施形態における現像装置において、高
抵抗層の層厚が８０μｍ，４０μｍ，６μｍになった各
現像剤担持体を用い、像担持体において露光された部分
の表面電位Ｖｉｒと現像剤担持体に印加させる直流電圧
Ｖｂとの差（Ｖｉｒ−Ｖｂ）を変化させて現像を行なっ
た場合において、形成された画像における透過濃度と上
記の（Ｖｉｒ−Ｖｂ）との関係を示した図である。
【図４】現像剤担持体における導電性基体を変更させた
この発明の他の実施形態に係る現像装置の概略断面図で
ある。
【符号の説明】
１ 像担持体
１１ 現像剤担持体
１１ｃ 導電性基体
１１ｄ 高抵抗層
１２ 現像剤（トナー）
Ｖｐｐ 現像剤担持体に作用させる交番電圧のピークピ
ーク値
Ｄ 現像剤担持体における導電性基体と像担持体とが対
向する間隔BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view of a developing device according to an embodiment of the present invention. FIG. 2 shows a developing device according to the above-described embodiment, in which each of the high-resistance layers has a thickness of 80 μm and 6 μm, and acts between the conductive substrate and the image bearing member in each developing agent. FIG. 7 is a diagram showing a relationship between the transmission density and the intensity of the alternating electric field (Vpp / D) in a formed image when development is performed while changing the intensity of the alternating electric field (Vpp / D) to be performed. FIG. 3 shows the developing device in the above-described embodiment, in which each of the high-resistance layers has a layer thickness of 80 μm, 40 μm, and 6 μm. FIG. 6 is a diagram showing the relationship between the transmission density in a formed image and the above (Vir-Vb) when development is performed while changing the difference (Vir-Vb) from the DC voltage Vb applied to the agent carrier. It is. FIG. 4 is a schematic cross-sectional view of a developing device according to another embodiment of the present invention in which a conductive substrate in a developer carrier is changed. DESCRIPTION OF REFERENCE NUMERALS 1 image carrier 11 developer carrier 11c conductive substrate 11d high resistance layer 12 developer (toner) Vpp peak-to-peak value D of alternating voltage applied to developer carrier D conductivity of developer carrier Distance between the substrate and the image carrier
───────────────────────────────────────────────────── フロントページの続き (72)発明者 藤枝 洋一 大阪市中央区安土町二丁目３番13号 大 阪国際ビル ミノルタ株式会社内 (56)参考文献 特開 昭60−254161（ＪＰ，Ａ) 特開 平３−39980（ＪＰ，Ａ) 特開 平１−239575（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) G03G 15/08 G03G 15/06 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoichi Fujieda 2-3-113 Azuchicho, Chuo-ku, Osaka-shi Osaka International Building Minolta Co., Ltd. (56) References JP-A-60-254161 (JP, A) JP-A-3-39980 (JP, A) JP-A-1-239575 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) G03G 15/08 G03G 15/06
Claims (1)
隔を介して対向するように設けられた現像剤担持体の表
面に現像剤を保持させ、この現像剤担持体によって現像
剤を像担持体と対向する現像領域に導くと共に、この現
像剤担持体に交番電圧を印加させて現像を行なう現像装
置において、上記の現像剤担持体として、導電性基体の
表面に、層厚が４０〜１２０μｍの範囲になった体積固
有抵抗値が１０ 10 Ω・ｃｍ以上の高抵抗層が設けられた
ものを用い、この現像剤担持体に印加させる上記の交番
電圧のピークピーク値Ｖｐｐ（ｋＶ）と、この現像剤担
持体における導電性基体と上記の像担持体とが対向する
間隔Ｄ（ｍｍ）とが、３ｋＶ／ｍｍ≦Ｖｐｐ／Ｄ≦８ｋ
Ｖ／ｍｍの関係を満たすことを特徴とする現像装置。(57) [Claim 1] A developer is held on a surface of a developer carrier provided so as to be opposed to an image carrier on which an electrostatic latent image is formed at a predetermined interval. In the developing device, which guides the developer to a development area facing the image carrier by the developer carrier and applies an alternating voltage to the developer carrier to perform development, the developer carrier is used as the developer carrier. to the surface of sexual base volume solid thickness became range of 40 to 120 [mu] m
Using a layer provided with a high resistance layer having a resistance value of 10 10 Ω · cm or more, the peak-to-peak value Vpp (kV) of the alternating voltage to be applied to the developer carrier, The distance D (mm) between the conductive substrate and the image carrier is 3 kV / mm ≦ Vpp / D ≦ 8 k
A developing device satisfying a relationship of V / mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12528997A JP3530877B2 (en) | 1997-05-15 | 1997-05-15 | Developing device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12528997A JP3530877B2 (en) | 1997-05-15 | 1997-05-15 | Developing device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10319717A JPH10319717A (en) | 1998-12-04 |
| JP3530877B2 true JP3530877B2 (en) | 2004-05-24 |
Family
ID=14906402
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12528997A Expired - Fee Related JP3530877B2 (en) | 1997-05-15 | 1997-05-15 | Developing device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3530877B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4333288B2 (en) * | 2003-09-03 | 2009-09-16 | コニカミノルタビジネステクノロジーズ株式会社 | Image forming apparatus |
-
1997
- 1997-05-15 JP JP12528997A patent/JP3530877B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10319717A (en) | 1998-12-04 |
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