JP4038405B2

JP4038405B2 - Image forming apparatus

Info

Publication number: JP4038405B2
Application number: JP2002196901A
Authority: JP
Inventors: 敏遠藤
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2002-07-05
Filing date: 2002-07-05
Publication date: 2008-01-23
Anticipated expiration: 2022-07-05
Also published as: JP2004037976A

Description

【０００１】
【発明の属する技術分野】
本発明は、表面に潜像を担持する回転可能な潜像担時体と、表面に現像剤を担持し、該潜像担持体に対向して該潜像担持体の回転方向と直交する方向に千鳥状に複数設けられた現像剤担持体とを有し、該潜像担持体上に形成された潜像に該現像剤担持体表面に担持する現像剤を供給し、該潜像担持体全域に亘って該潜像を現像する現像装置を備える画像形成成装置に関するものである。
【０００２】
【従来の技術】
従来、プリンタ、ファクシミリ、複写機等の画像形成装置においては、単色の画像形成を行う場合、表面に潜像を担持する潜像担持体に対して、同等の有効幅をもつ現像剤担持体を備え、該潜像担持体上に形成された潜像に該現像剤担持体表面に担持する現像剤を供給する現像装置が用いられている。また、現像方式のプロセスに関しては、有効幅に関係なく、現像剤担持体と該現像剤担持体に担持されて搬送される現像剤の層厚を規制する現像剤規制部材とが同じ幅になるのが理想的である。
しかしながら、現在実用化されている広幅機器の画像形成装置に関しては、同じ有効幅をもつ潜像担持体と現像剤担持体とで一対の現像装置を構成した場合、部品が大きく重量が増え、撓み等の影響が少なからず生じるため、部品の剛性が必要である。そのために、部品の成形にも大型機器が必要となり、コストがかかっていた。
そこで、大型で高重量のこれまでの現像装置にかわって、小型化された現像装置を潜像担持体に対向して該潜像担持体の回転方向と直交する方向に複数配設する画像形成装置が提案されている。しかし、現像装置を一列に複数並べただけでは、装置間に隙間が生じてしまう。したがって、現像装置の端部が重なるように現像装置を千鳥状に配置して、潜像担持体の有効幅全域に亘って現像可能としている。これにより、現像機能を損なうことなく、現像装置の小型化が可能となる。また、現像装置全体の重量も低減され、その保持部材の強度も低減できるため、低コスト化を図ることができる。さらに、普及機の現像ユニットや、部品をそのまま流用することが可能となるため、生産性を高めることができ、更なる低コスト化を図ることができる。
【０００３】
特開平２０００−３１０８９２号公報においては、感光体上の静電潜像に現像剤を供給する現像剤担持体を記録体搬送方向と直交する方向に複数備えるとともに、各現像剤剤担持体に印加する現像バイアス電圧値をそれぞれ変更可能な分割現像手段と、各現像剤担持体に印加する現像バイアス電圧を補正する現像条件補正手段とを有する画像形成装置が提案されている。この画像形成装置においては、初期状態と所定の検出タイミングとで記録体のうち記録体搬送方向と直交する方向についての位置が異なる２カ所以上で定着テスト画像の画像情報を検出し、これら画像情報の比較結果に基づいて画像状態が初期状態に近づけるように各現像剤担持体に印加する現像バイアス値をそれぞれ補正する。これにより、初期状態における画像状態を維持した定着画像を得ることができる。
【０００４】
【発明が解決しようとする課題】
ところが、上述したように潜像担持体に対して複数の現像装置を千鳥状に並べて配置した場合には、現像剤担持体が重なる領域で二重に現像を行うことになる（以下、二重現像領域という）ので、この二重現像領域と該二重現像領域以外の現像領域（以下、他の現像領域という）とで潜像担持体上の画像の濃度に差異が生じてしまう。例えば、二重現像領域では、潜像担持体上にトナー像が二重に重ねられて現像されるので、最終的に他の現像領域に比べ画像濃度が濃くなってしまう。一方、現像剤の性質によっては、二重現像領域において、潜像担持体の回転方向上流側に配置された現像剤担持体によって現像されたトナー像が、潜像担持体の回転方向下流側に配置された現像剤担持体に担持された現像剤によって掻き落とされるため、最終的に他の現像領域に比べ画像濃度が薄くなる場合がある。特開平２０００−３１０８９２号公報においては、この二重現像領域と他の現像領域との画像濃度の差異については触れられていない。
【０００５】
本発明は以上の問題点に鑑みなされたものであり、その目的とするところは、複数の現像剤担持体が千鳥状に配置される画像形成装置において、二重現像領域と他の現像領域とでの画像濃度差を低減し、画像濃度の均一化を図ることができる画像形成装置を提供することである。
【０００６】
【課題を解決するための手段】
上記目的を達成するために、請求項１の画像形成装置は、表面に潜像を担持する回転可能な潜像担時体と、該複数の現像剤担持体の上記潜像担持体の回転軸方向の長さである幅が上記潜像担持体の幅よりも短く、かつ表面に担持した現像剤を回転によって該潜像担持体の表面に供給する複数の現像剤担持体とを有し、隣り合う現像剤担持体の上記潜像担持体の回転方向の配置位置は互いに異なり、かつ、隣り合う現像剤担持体の幅方向の位置は互いの端部のみが互いに重なるように、上記複数の現像剤担持体が上記幅方向に並べて配置され、現像領域にて上記潜像担持体上に形成された潜像に上記複数の現像剤担持体表面に担持する現像剤を供給し、上記潜像担持体全域に亘って上記潜像を現像する現像装置を備える画像形成装置において、上記幅方向の位置が重なる上記隣り合う現像剤担持体の端部で二重に現像が行われる二重現像領域と該二重現像領域以外の他の現像領域とで画像濃度が同等となるように、各現像剤担持体が上記潜像担持体に供給する現像剤の供給量を二重現像領域と他の領域とで異ならせることを特徴とするものである。
この画像形成装置においては、複数設けられた現像剤担持体のうち、潜像担持体の回転方向上流側に設けられた現像担持体によってまず現像が行われ、その後に潜像担持体の回転方向下流側に設けられた現像剤担持体によって現像が行われ、隣り合う現像剤担持体の幅方向の端部が重なる部分で二重に現像が行われる二重現像領域が存在するが、二重現像領域で二重現像されて形成される画像と、他の領域で形成される画像の画像濃度が同等となるように、各現像剤担持体が該潜像担持体に供給する現像剤の供給量を二重現像領域と他の領域とで異ならせている。したがって、二重現像領域で形成された画像と他の現像領域げ形成された画像との画像濃度差を低減することが可能となる。
請求項２の画像形成装置は、請求項１の画像形成装置において、上記現像剤担持体で担持され上記現像領域に向けて搬送される現像剤の層厚を規制する現像剤規制部材が、上記現像剤担持体の表面との間に所定の間隔をおいて対向配置され、該現像剤担持体と該現像剤規制部材との間隔を、上記二重現像領域と上記他の現像領域とで異ならせることによって、上記現像剤の供給量を二重現像領域と他の領域とで異ならせることを特徴とするものである。
請求項３の画像形成装置は、請求項２の画像形成装置において、上記現像剤規制部材の形状を、上記二重現像領域に対応する端部が上記他の現像領域に対応する部分よりも上記現像担持体表面側に接近するように突き出た形状にすることによって、上記間隔を、上記二重現像領域と上記他の現像領域とで異ならせることを特徴とするものである。
請求項４の画像形成装置は、請求項３の画像形成装置において、上記現像剤規制部材の上記端部の形状が幅方向外側ほど連続的に突き出し量が大きくなるような形状であることを特徴とするものである。
請求項５の画像形成装置は、請求項２の画像形成装置において、上記現像剤担持体表面の形状を、上記二重現像領域に対応する部分が上記他の現像領域に対応する部分よりも上記現像剤規制部材側に接近するように突き出た形状にすることによって、上記間隔を、上記二重現像領域と上記他の現像領域とで異ならせることを特徴とするものである。
請求項６の画像形成装置は、請求項５の画像形成装置において、上記現像剤担持体の上記二重現像領域に対応する部分の表面形状が対応する現像剤規制部材の端部外側ほど連続的に突き出し量が大きくなるような形状であることを特徴とするものである。
請求項７の画像形成装置は、請求項２の画像形成装置において、上記現像剤担持体表面の形状を、上記二重現像領域に対応する部分が上記他の現像領域に対応する部分よりも上記現像剤規制部材から離間するように凹んだ形状にすることによって、上記間隔を、上記二重現像領域と上記他の現像領域とで異ならせることを特徴とするものである。
請求項８の画像形成装置は、請求項７の画像形成装置において、上記現像剤担持体の上記二重現像領域に対応する部分の表面形状が対応する現像剤規制部材の端部外側ほど連続的に凹み量が大きくなるような形状であることを特徴とするものである。
【０００７】
【発明の実施の形態】
以下、本発明を画像形成装置である白黒画像用広幅電子写真複写機（以下、複写機という）に適用した第１の実施形態について説明する。図１は本実施形態に係る複写機の一部部分を示す概略構成図である。矢印Ａ方向に回転する潜像担持体としてのドラム状感光体１の周囲には、感光体１の表面を一様に帯電せしめる帯電装置２、感光体１の表面にレーザ光による光書き込みを行って静電潜像を形成する露光光学装置３、感光体１上の静電潜像を現像してトナー像を形成する現像装置４（４Ａ，４Ｂ，４Ｃ）、現像装置４で得られたトナー像を記録媒体である転写紙に転写し、転写紙を感光体１から分離せしめる転写・分離装置５、転写・分離装置５によって転写紙上に転写されたトナー像を定着する定着装置６、トナー像の転写後に感光体１上に残留するトナーをクリーニングブレード７ａによって掻き落すクリーニング装置７、次の画像形成に備えて感光体１を除電する除電装置８等が各々近接あるいは接触するようにして配設されている。
【０００８】
上記構成の複写機は、上記帯電装置２により感光体１の表面を均一に帯電し、露光装置３によって図示しないレーザ光学系からの画像情報に基づくレーザ光によって該感光体１表面に静電潜像を形成する。上記感光体１上の静電潜像は、現像装置４Ａ，４Ｂ，４Ｃにより現像され、感光体１上にはトナー像が形成される。その後、このトナー像は、感光体１と転写・分離装置５との対向領域で、図示しない給紙カセットから給紙搬送された転写紙上に転写される。このようにして、転写紙に転写されたトナー像は、上記定着装置６の定着ローラ６ａと加圧ローラ６ｂとの作用を受けて転写紙上に定着される。一方、この転写時に上記感光体１上に残留した転写残トナーは、上記クリーニング装置７のクリーニングブレード７ａにより除去され、感光体１上に残留した残留電荷は除電装置８により除電される。そして、クリーニング及び除電された感光体１は次の画像形成工程に供される。なお、この画像形成装置のコピー動作については、周知の電子写真プロセスであるので説明は省略する。
【０００９】
次に、本実施形態の特徴部となる現像装置４について説明する。図２は、現像領域の概略構成を示す構成図である。図３は、現像領域の概略構成を示す斜視図である。図４は、現像領域の概略構成を示す正面図である。現像装置４は、図１乃至図３に示すように、感光体１に対向して感光体１の回転方向と直交する方向に複数並ぶように、現像剤担持体としての第１現像ローラ１１Ａ、第２現像ローラ１１Ｂ、第３現像ローラ１１Ｃが千鳥状に配設されている。ここでは、第１現像ローラ１１Ａと第３現像ローラ１１Ｃが感光体１の円周方向における同角度位置に設けられ、第２現像ローラ１１Ｂが第１現像ローラ１１Ａ及び第３現像ローラ１１Ｃよりも感光体１の回転方向下流側に設けられている。そして、現像装置４には、トナー補給装置から補給されたトナーを現像装置４Ａ，４Ｂ，４Ｃ内の現像剤と混合攪拌するとともに現像ローラ１１Ａ〜１１Ｃに供給するための搬送スクリュー１２Ａ〜１２Ｃ，１３Ａ〜１３Ｃ、現像ローラ１１Ａ〜１１Ｃ上の現像剤の層厚を規制する現像剤規制部材としての現像ドクタ１４Ａ〜１４Ｃ等が配設されている。現像ドクタ１４Ａ〜１４Ｃは、図２に示すように、その先端と現像ローラ１１Ａ〜１１Ｃの外周面との間に一定の間隔（以下、ドクタギャップという）１５Ａ〜１５Ｃを保った状態で配設されている。
【００１０】
このように構成される現像装置４において、トナー補給装置から現像装置４Ａ〜４Ｃ内に補給されたトナーは、搬送スクリュー１２Ａ〜１２Ｃ，１３Ａ〜１３Ｃの回転に伴い、現像剤と混合・攪拌されながら現像ローラ１１Ａ〜１１Ｃへと搬送される。現像ローラ１１Ａ〜１１Ｃ表面に担持された現像剤は、矢印Ｂ方向に回転する現像ローラ１１Ａ〜１１Ｃの回転に伴って現像ドクタ１４Ａ〜１４Ｃにより層厚が規制され、感光体１との対向領域である現像領域まで搬送される。そして、現像領域に搬送された現像剤中のトナーが、上記感光体１上に形成された潜像に供給され、感光体１の全域に亘って該潜像の現像が行われてトナー像が形成される。
【００１１】
ところで、図４に示すように、現像装置４においては、画像領域の全てを現像可能とするために、現像ローラ１１Ａ〜１１Ｃ間に隙間が発生しないように現像ローラ１１Ａ〜１１Ｃが千鳥状に配置されている。したがって、千鳥状に複数設けられた現像ローラ１１Ａ〜１１Ｃのうち、感光体１の回転方向上流側に設けられた現像ローラ１１Ａ，１１Ｃ［によってまず現像が行われ、その後に感光体１の回転方向下流側に設けられた現像ローラ１１Ｂによって現像が行われるため、二重に現像が行われる二重現像領域が生じる。そこで、本実施形態に係る現像装置４においては、二重現像領域１６のドクタギャップが、他の現像領域１７のドクタギャップより小さくなるように、現像ドクタ１４Ａ〜１４Ｃの組み付け調整を行っている。これにより、各現像ローラ１１Ａ〜１１Ｃが感光体１へ供給するトナーのトナー供給量が他の現像領域１７に比べ二重現像領域１６で少なくなる。その結果、二重現像領域１６で二重現像されたトナー像と他の現像領域１７で現像されたトナー像の画像濃度が同等となり、二重現像領域と他の現像領域とでのトナー像の画像濃度差を低減することができる。
【００１２】
次に、第二の実施形態について説明する。以下、現像ドクタの形状以外は、第一の実施形態で説明したものと同様の構成であるので説明を省略する。図５は、本実施形態に係る現像ドクタの形状を説明する斜視図である。現像能力、例えば現像ローラ１１内部に配置された磁界発生手段の性能によっては、第一の実施形態で説明した現像ドクタ１４Ａ〜１４Ｃの組み付け調整だけでは、感光体１へのトナー供給量を調整するのが困難な場合がある。そこで、本実施形態に係る現像ドクタ２１は、図５に示すように、二重現像領域の突き出し量２１ａが他の現像領域の突き出し量２１ｂよりも大きく形成されている。これにより、二重現像領域のドクタギャップが他の現像領域のドクタギャップより小さくなり、二重現像領域で現像ローラ１１Ａ，１１Ｂ，１１Ｃが感光体１に供給するトナー供給量を少なくすることができる。その結果、二重現像領域で二重現像されたトナー像と他の現像領域で現像されたトナー像との画像濃度が同等となり、二重現像領域と他の現像領域とでのトナー像の画像濃度差を低減することができる。ここでは、現像ドクタ２１は、二重現像領域で二重現像されたトナー像と他の現像領域で現像されたトナー像の画像濃度が同等となるよう予め確認された突き出し量にて成形される。なお、本実施形態においては、千鳥状に配置された現像ローラ１１Ａ，１１Ｂ，１１Ｃのうち中央部に配置された現像ローラ１１Ｂに対向して設けられた現像ドクタ２１の形状について説明したが、該現像ローラ１１Ａ，１１Ｃに対向してそれぞれ設けられた現像ドクタについても、同様に構成されることはいうまでもない。
【００１３】
次に、第三の実施形態について説明する。以下、現像ドクタの形状以外は、第一の実施形態で説明したものと同様の構成であるので説明を省略する。図６は、本実施形態に係る現像ドクタの形状を説明する斜視図である。現像ドクタの突き出し量が、第二の実施形態で説明したように二重現像領域と他の現像領域との間で急激に変化しそれが過剰である場合には、その部分が境界線となって画像に現れてしまう。そこで、本実施形態に係る現像ドクタ２２は、図６に示すように、二重現像領域の突き出し量２２ａが、他の現像領域の突き出し量２２ｂから連続的に大きくなるように形成されている。これにより、二重現像領域のドクタギャップが他の現像領域のドクタギャップより連続的に大きくなり、感光体１上のトナー像の画像濃度が二重現像領域と他の現像領域との境界で急激に変化するのを抑えることができる。そして、二重現像領域と他の現像領域とでのトナー像の画像濃度差を低減することができる。なお、ここでは、千鳥状に配置された現像ローラ１１Ａ，１１Ｂ，１１Ｃのうち中央部に配置された現像ローラ１１Ｂの現像ドクタ２２の形状について説明したが、該現像ローラ１１Ａ，１１Ｃに対向してそれぞれ設けられた現像ドクタについても、同様に構成されることはいうまでもない。
【００１４】
次に、第四の実施形態について説明する。以下、現像ローラの形状以外は、第一の実施形態で説明したものと同様の構成であるので説明を省略する。図７は、本実施形態に係る現像ローラ２３の形状を説明する部分拡大図である。現像能力、例えば現像ローラ内部に配置された磁界発生手段の性能によっては、第一の実施形態で説明したような現像ドクタ１４Ａ〜１４Ｃの組み付け調整だけでは、感光体１へのトナー供給量を調整するのが困難な場合がある。そこで、本実施形態においては、感光体１と現像ローラ２３との間隔が他の現像領域に比べ二重現像領域で小さくなるように調整する。図７に示すように、現像ローラ２３Ａ〜２３Ｃは、二重現像領域の現像ローラ径２３ａＡ〜２３ａＣが他の現像領域１７の現像ローラ径２３ｂＡ〜２３ｂＣよりも大きく形成されている。これにより、各現像ローラ２３Ａ〜２３Ｃの二重現像領域のドクタギャップが他の現像領域のドクタギャップより小さくなり、二重現像領域で感光体１へのトナー供給量を少なくすることができる。その結果、二重現像領域で二重現像されたトナー像と他の現像領域で現像されたトナー像との画像濃度が同等となり、二重現像領域と他の現像領域とでのトナー像の画像濃度差を低減することができる。
【００１５】
次に、第五の実施形態について説明する。以下、現像ローラの形状以外は、第一の実施形態で説明したものと同様の構成であるので説明を省略する。図８は、本実施形態に係る現像ローラ２４の形状を説明する部分拡大図である。現像ローラの径が、第四の実施形態で説明したように二重現像領域と他の現像領域との間で急激に変化しそれが過剰である場合には、その部分が境界線となって画像に現れてしまう。そこで、本実施形態に係る現像ローラ２４Ａ〜２４Ｃは、図８に示すように、二重現像領域の現像ローラ径２４ａＡ〜２４ａＣが、他の現像領域の現像ローラ径２４ｂＡ〜２４ｂＣから連続的に大きくなるように形成されている。これにより、二重現像領域のドクタギャップが他の現像領域のドクタギャップより連続的に大きくなり、感光体１上のトナー像の画像濃度が二重現像領域と他の現像領域との間で急激に変化するのを抑えることができる。そして、二重現像領域と他の現像領域とでのトナー像の画像濃度差を低減することができる。
【００１６】
次に、第六の実施形態について説明する。以下、現像ローラの形状以外は、第一の実施形態で説明したものと同様の構成であるので説明を省略する。図９は、本実施形態に係る現像ローラ２５の形状を説明する部分拡大図である。現像剤の性質によって、二重現像領域では、感光体１の回転方向上流側に配置された現像ローラ２５Ａ，２５Ｃによって現像された感光体１上のトナー像が、感光体１の回転方向下流側に配置された現像ローラ２５Ｂに担持された現像剤によって掻き落とされるため、感光体１上に形成されたトナー像の画像濃度が薄くなる場合がある。そこで、本実施形態においては、感光体１と現像ローラ２５との間隔が他の現像領域に比べ二重現像領域で大きくなるように調整する。図９に示すように、現像ローラ２５Ａ〜２５Ｃは、二重現像領域の現像ローラ径２５ａＡ〜２５ａＣが他の現像領域の現像ローラ径２５ｂＡ〜２５ｂＣよりも小さく形成されている。これにより、二重現像領域のドクタギャップが他の現像領域のドクタギャップより大きくなり、二重現像領域で各現像ローラ２５Ａ〜２５Ｃが感光体１に供給するトナー供給量を多くすることができる。その結果、二重現像領域で二重現像されたトナー像と他の現像領域で現像されたトナー像との画像濃度が同等となり、二重現像領域と他の現像領域とでのトナー像の画像濃度差を低減することができる。
【００１７】
次に、第七の実施形態について説明する。以下、現像ローラの形状以外は、第一の実施形態で説明したものと同様の構成であるので説明を省略する。図１０は、本実施形態に係る現像ローラ２６の形状を説明する部分拡大図である。現像ローラの径が、第六の実施形態で説明したように二重現像領域と他の現像領域との間で急激に変化しそれが過剰である場合には、その部分が境界線となって画像に現れてしまう。そこで、本実施形態に係る現像ローラ２６Ａ〜２６Ｃは、図１０に示すように、二重現像領域の現像ローラ径２６ａＡ〜２６ａＣが、他の現像領域の現像ローラ径２６ｂＡ〜２６ｂＣから連続的に小さくなるように形成されている。これにより、二重現像領域のドクタギャップが他の現像領域のドクタギャップより連続的に大きくなり、感光体１上のトナー像の画像濃度が二重現像領域と他の現像領域との間で急激に変化するのを抑えることができる。そして、二重現像領域と他の現像領域とでのトナー像の画像濃度差を低減することができる。
【００１８】
なお、第一〜第七の実施形態においては、現像ローラから感光体に供給するトナーのトナー供給量を二重現像領域と他の現像領域路で異なるように調整するために、ドクタギャップの調整、感光体と現像ローラとの間隔の調整（現像ローラの径の調整）を行ったが、これに限定されるものではない。二成分現像剤を用いる場合には、上述した調整以外にも、二重現像領域で現像ローラに担持される現像剤量を調節するために、現像ローラ内部に設置される磁界発生手段の磁力分布を調整してもよい。また、トナー供給手段で現像ローラに一成分現像剤を供給する場合には、二重現像領域と他の現像領域とでのトナー供給能力が異なるようにトナー供給手段を形成してもよい。例えばトナー供給手段として現像ローラに一成分現像剤を擦りつけて供給するトナー供給ローラを用いる場合には、二重現像領域に対応するトナー供給ローラ表面部分と他の部分との摩擦係数が異なるように形成する。また、一成分現像剤と二成分現像剤のいずれかを使用する場合、二重現像領域と他の現像領域での現像剤担持能力あるいは搬送能力が異なるように、この二重現像領域に対応する現像ローラの表面部分を他の部分と異なる表面構造にしてもよい。例えば、この二重現像領域に対応する現像ローラ表面部分の摩擦係数が他の部分よりも小さくなるように形成する。
また、第一〜第七の実施形態においては、白黒画像用複写機に適用したものについて説明したが、カラー画像用複写機に適用してもよいことは言うまでもない。ドラム状の潜像担持体、現像剤担持体を用いる場合について説明したが、ベルト状の潜像担持体、現像剤担持体であってもよい。
【００１９】
【発明の効果】
本発明の画像形成装置によれば、複数の現像剤担持体を隣り合うもの同士が現像剤担持体回転方向で互いに異なる位置になるよう、かつ隣り合うもの同士の端部のみが幅方向で互いに重なるように、幅方向に並べて配置される画像形成装置において、二重現像領域と他の現像領域とでの画像濃度差を低減し、画像濃度の均一化を図ることができるという優れた効果がある。
【図面の簡単な説明】
【図１】第一の実施形態に係る複写機の一部分を示す概略構成図。
【図２】同複写機における現像装置の現像領域の概略構成を示す概略構成図。
【図３】同現像装置の現像領域の概略構成を示す斜視図。
【図４】同現像装置の現像領域の概略構成を示す正面図。
【図５】第二の実施形態に係る現像装置の現像ドクタの形状を説明する斜視図。
【図６】第三の実施形態に係る現像装置の現像ドクタの形状を説明する斜視図。
【図７】第四の実施形態に係る現像装置の現像ローラの形状を説明する部分拡大図。
【図８】第五の実施形態に係る現像装置の現像ローラの形状を説明する部分拡大図。
【図９】第六の実施形態に係る現像装置の現像ローラの形状を説明する部分拡大図。
【図１０】第七の実施形態に係る現像装置の現像ローラの形状を説明する部分拡大図。
【符号の説明】
１感光体
４現像装置
１１，２３，２４，２５，２６現像ローラ
１４，２１，２２現像ドクタ
１５ドクタギャップ
１６二重現像領域
１７他の現像領域[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotatable latent image carrier that carries a latent image on the surface, a developer that carries the developer on the surface, and a direction that faces the latent image carrier and is orthogonal to the rotation direction of the latent image carrier. A plurality of developer carriers provided in a zigzag manner, and supplying the developer carried on the surface of the developer carrier to the latent image formed on the latent image carrier, the latent image carrier The present invention relates to an image forming apparatus including a developing device that develops the latent image over the entire area.
[0002]
[Prior art]
Conventionally, in image forming apparatuses such as printers, facsimiles, copiers, and the like, when carrying out monochromatic image formation, a developer carrying body having an equivalent effective width is provided for a latent image carrying body carrying a latent image on the surface. And a developing device for supplying a developer carried on the surface of the developer carrying member to the latent image formed on the latent image carrying member. In addition, regarding the development process, the developer carrying member and the developer regulating member that regulates the layer thickness of the developer carried and conveyed by the developer carrying member have the same width regardless of the effective width. Is ideal.
However, regarding image forming apparatuses for wide-width devices that are currently in practical use, when a pair of developing devices are constituted by a latent image carrier and a developer carrier having the same effective width, the parts are greatly increased in weight and bent. Therefore, the rigidity of the parts is necessary. For this reason, large-scale equipment is required for molding the parts, which is costly.
Therefore, in place of the large and heavy conventional developing device, a plurality of miniaturized developing devices are arranged opposite to the latent image carrier in a direction perpendicular to the rotation direction of the latent image carrier. A device has been proposed. However, if only a plurality of developing devices are arranged in a row, a gap is generated between the devices. Accordingly, the developing devices are arranged in a staggered manner so that the end portions of the developing devices overlap, and development is possible over the entire effective width of the latent image carrier. As a result, the developing device can be downsized without impairing the developing function. Further, the weight of the entire developing device is reduced, and the strength of the holding member can be reduced, so that the cost can be reduced. Furthermore, since it becomes possible to divert the developing unit and parts of the popular machine as they are, productivity can be improved and further cost reduction can be achieved.
[0003]
In Japanese Patent Application Laid-Open No. 2000-310892, a plurality of developer carriers for supplying a developer to an electrostatic latent image on a photoreceptor are provided in a direction perpendicular to the recording material transport direction, and applied to each developer carrier. There has been proposed an image forming apparatus having divided developing means capable of changing each developing bias voltage value and developing condition correcting means for correcting the developing bias voltage applied to each developer carrier. In this image forming apparatus, the image information of the fixing test image is detected at two or more positions of the recording medium that differ in the direction orthogonal to the recording medium conveyance direction between the initial state and a predetermined detection timing. Based on the comparison result, the developing bias value applied to each developer carrier is corrected so that the image state approaches the initial state. Thereby, it is possible to obtain a fixed image that maintains the image state in the initial state.
[0004]
[Problems to be solved by the invention]
However, when a plurality of developing devices are arranged in a zigzag pattern on the latent image carrier as described above, development is performed twice in the region where the developer carrier overlaps (hereinafter referred to as “double”). Therefore, there is a difference in the image density on the latent image carrier between the double development area and a development area other than the double development area (hereinafter referred to as another development area). For example, in the double development area, the toner image is developed in a duplicated manner on the latent image carrier, so that the image density finally becomes higher than that in the other development areas. On the other hand, depending on the nature of the developer, in the double development region, the toner image developed by the developer carrier disposed on the upstream side in the rotation direction of the latent image carrier may be on the downstream side in the rotation direction of the latent image carrier. Since it is scraped off by the developer carried on the arranged developer carrying member, the image density may eventually become thinner than other development regions. Japanese Patent Application Laid-Open No. 2000-310892 does not mention the difference in image density between the double development area and other development areas.
[0005]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a double development area and other development areas in an image forming apparatus in which a plurality of developer carriers are arranged in a staggered manner. It is an object to provide an image forming apparatus capable of reducing the difference in image density and making the image density uniform.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an image forming apparatus according to claim 1 includes a rotatable latent image carrier for carrying a latent image on a surface, and a rotation shaft of the latent image carrier of the plurality of developer carriers. A width that is the length of the direction is shorter than the width of the latent image carrier, and a plurality of developer carriers that supply the developer carried on the surface to the surface of the latent image carrier by rotation , The arrangement positions of the adjacent developer carriers in the rotation direction of the latent image carriers are different from each other, and the positions of the adjacent developer carriers in the width direction are such that only the ends overlap each other. developer carrying member is arranged in the width direction, supplying a developer carried on the plurality of the developer carrying member surface to the latent image formed on said image bearing member in the developing region, the latent image an image forming apparatus comprising a developing apparatus for developing the latent image over the carrier throughout As the image density is equal in double developing region and other developing region other than said double developing region where the developing at the ends of the adjacent developer carrier position of the serial width direction overlaps doubly is performed the one in which the developer carrying member is characterized by varying the supply amount of the developer supplied to the latent image carrier with a double developing region and other regions.
In the image forming apparatus, of the developer carrying member provided several, first development is performed by a developing carrying member provided on the upstream side of the rotation direction of the latent image bearing member, followed by rotation of the image bearing member There is a double development area where the development is performed by the developer carrier provided on the downstream side in the direction and the development is performed twice at the portion where the end portions in the width direction of adjacent developer carriers overlap. The developer supplied to the latent image carrier by each developer carrier so that the image density of the image formed by double development in the heavy development region and the image formed in the other region are equal. The supply amount is made different between the double development area and the other areas. Therefore, it is possible to reduce an image density difference between an image formed in the double development area and an image formed in another development area.
The image forming apparatus according to claim 2, in the image forming apparatus according to claim 1, the current image-regulating member that the thickness Wins regulations of the developer conveyed toward the supported by the developer carrying member the developing region , are located opposite each other with a predetermined distance between the surface of the developer carrying member, the distance between the developer carrying member and the developer regulating member, and the double-developing region and said another developing region in by causing different al, it is characterized in Rukoto by varying the supply amount of the developer in a double development region and other regions.
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect , the shape of the developer restricting member is set to be greater than a portion where an end corresponding to the double development region corresponds to the other development region. By forming a shape protruding so as to approach the surface of the development carrier, the interval is made different between the double development region and the other development region .
According to a fourth aspect of the present invention, in the image forming apparatus of the third aspect, the shape of the end of the developer regulating member is such that the protruding amount continuously increases toward the outer side in the width direction. It is what.
The image forming apparatus according to claim 5, in the image forming apparatus according to claim 2, the shape of the upper Symbol developer carrying member surface, than the portion the portion corresponding to the double-developing region corresponding to the other developing areas By making the shape protruding so as to approach the developer regulating member side, the interval is made different between the double development region and the other development region .
The image forming apparatus according to a sixth aspect is the image forming apparatus according to the fifth aspect, wherein the surface shape of the portion corresponding to the double development region of the developer carrying member is continuous toward the outer side of the end portion of the corresponding developer regulating member. The shape is such that the protruding amount increases .
An image forming apparatus according to a seventh aspect is the image forming apparatus according to the second aspect, wherein the surface of the developer carrying member is shaped so that the portion corresponding to the double developing region corresponds to the other developing region. By forming a concave shape so as to be separated from the developer regulating member, the interval is made different between the double development region and the other development region.
An image forming apparatus according to an eighth aspect is the image forming apparatus according to the seventh aspect, wherein the surface shape of the portion corresponding to the double development region of the developer carrying member is continuous toward the outer side of the end of the corresponding developer regulating member. The shape is such that the dent amount increases.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment in which the present invention is applied to a wide-width electrophotographic copying machine for monochrome images (hereinafter referred to as a copying machine) as an image forming apparatus will be described. FIG. 1 is a schematic configuration diagram showing a part of the copying machine according to the present embodiment. Around the drum-shaped photoconductor 1 as a latent image carrier rotating in the direction of arrow A, a charging device 2 for uniformly charging the surface of the photoconductor 1, and optical writing with a laser beam is performed on the surface of the photoconductor 1. The exposure optical device 3 for forming an electrostatic latent image, the developing device 4 (4A, 4B, 4C) for developing the electrostatic latent image on the photoreceptor 1 to form a toner image, and the toner obtained by the developing device 4 A transfer / separation device 5 for transferring the image onto a transfer paper as a recording medium and separating the transfer paper from the photosensitive member 1; a fixing device 6 for fixing the toner image transferred onto the transfer paper by the transfer / separation device 5; The cleaning device 7 for scraping off the toner remaining on the photosensitive member 1 by the cleaning blade 7a after the transfer of the toner, the neutralizing device 8 for neutralizing the photosensitive member 1 in preparation for the next image formation, etc. Has been.
[0008]
The copying machine having the above configuration uniformly charges the surface of the photosensitive member 1 by the charging device 2, and electrostatic exposure is performed on the surface of the photosensitive member 1 by laser light based on image information from a laser optical system (not shown) by the exposure device 3. Form an image. The electrostatic latent image on the photosensitive member 1 is developed by the developing devices 4A, 4B, and 4C, and a toner image is formed on the photosensitive member 1. Thereafter, the toner image is transferred onto a transfer sheet fed and conveyed from a sheet feeding cassette (not shown) in a region where the photosensitive member 1 and the transfer / separation device 5 face each other. In this way, the toner image transferred onto the transfer paper is fixed on the transfer paper under the action of the fixing roller 6a and the pressure roller 6b of the fixing device 6. On the other hand, the transfer residual toner remaining on the photosensitive member 1 at the time of the transfer is removed by the cleaning blade 7a of the cleaning device 7, and the residual charge remaining on the photosensitive member 1 is discharged by the charge removing device 8. Then, the cleaned and neutralized photoreceptor 1 is subjected to the next image forming process. Since the copying operation of the image forming apparatus is a well-known electrophotographic process, description thereof is omitted.
[0009]
Next, the developing device 4 that is a characteristic part of the present embodiment will be described. FIG. 2 is a configuration diagram showing a schematic configuration of the development area. FIG. 3 is a perspective view showing a schematic configuration of the developing region. FIG. 4 is a front view showing a schematic configuration of the development region. As shown in FIGS. 1 to 3, the developing device 4 includes a first developing roller 11 A as a developer carrying member, which is arranged in a plurality in a direction orthogonal to the rotation direction of the photosensitive member 1 so as to face the photosensitive member 1. The second developing roller 11B and the third developing roller 11C are arranged in a staggered manner. Here, the first developing roller 11A and the third developing roller 11C are provided at the same angular position in the circumferential direction of the photoreceptor 1, and the second developing roller 11B is more sensitive than the first developing roller 11A and the third developing roller 11C. It is provided on the downstream side in the rotation direction of the body 1. The developing device 4 includes conveying screws 12A to 12C and 13A for mixing and stirring the toner replenished from the toner replenishing device with the developer in the developing devices 4A, 4B and 4C and supplying the toner to the developing rollers 11A to 11C. To 13C, developer doctors 14A to 14C as developer regulating members for regulating the layer thickness of the developer on the developing rollers 11A to 11C are disposed. As shown in FIG. 2, the developing doctors 14 A to 14 C are arranged in a state where a constant interval (hereinafter referred to as doctor gap) 15 A to 15 C is maintained between the tip of the developing doctors 14 A to 14 C. ing.
[0010]
In the developing device 4 configured as described above, the toner replenished from the toner replenishing device into the developing devices 4A to 4C is mixed and stirred with the developer as the conveying screws 12A to 12C and 13A to 13C rotate. It is conveyed to the developing rollers 11A to 11C. The developer carried on the developing rollers 11 A to 11 C has its layer thickness restricted by the developing doctors 14 A to 14 C as the developing rollers 11 A to 11 C rotate in the direction of arrow B, and is in a region facing the photoreceptor 1. It is conveyed to a certain development area. Then, the toner in the developer transported to the development area is supplied to the latent image formed on the photosensitive member 1, and the latent image is developed over the entire area of the photosensitive member 1 to form a toner image. It is formed.
[0011]
As shown in FIG. 4, in the developing device 4, the developing rollers 11 A to 11 C are arranged in a staggered manner so that no gap is generated between the developing rollers 11 A to 11 C so that the entire image area can be developed. Has been. Accordingly, among the plurality of developing rollers 11A to 11C provided in a staggered manner, development is first performed by the developing rollers 11A and 11C [provided on the upstream side in the rotational direction of the photosensitive member 1, and then the rotational direction of the photosensitive member 1 is performed. Since the development is performed by the developing roller 11B provided on the downstream side, a double development region where the development is performed twice is generated. Therefore, in the developing device 4 according to the present embodiment, the assembly adjustment of the developing doctors 14A to 14C is performed so that the doctor gap of the double developing region 16 is smaller than the doctor gap of the other developing regions 17. As a result, the toner supply amount of the toner supplied to the photosensitive member 1 by each of the developing rollers 11 A to 11 C is smaller in the double developing region 16 than in the other developing regions 17. As a result, the toner images double-developed in the double development area 16 and the toner images developed in the other development areas 17 have the same image density, and the toner images in the double development area and the other development areas are the same. An image density difference can be reduced.
[0012]
Next, a second embodiment will be described. Since the configuration other than the shape of the developing doctor is the same as that described in the first embodiment, the description thereof will be omitted. FIG. 5 is a perspective view for explaining the shape of the developing doctor according to the present embodiment. Depending on the developing ability, for example, the performance of the magnetic field generating means disposed inside the developing roller 11, the toner supply amount to the photosensitive member 1 is adjusted only by adjusting the assembly of the developing doctors 14A to 14C described in the first embodiment. It can be difficult. Therefore, as shown in FIG. 5, the developing doctor 21 according to the present embodiment is formed such that the protruding amount 21a of the double developing area is larger than the protruding amount 21b of the other developing areas. As a result, the doctor gap in the double development area becomes smaller than the doctor gap in the other development areas, and the amount of toner supplied from the developing rollers 11A, 11B, and 11C to the photoreceptor 1 in the double development area can be reduced. . As a result, the image density of the toner image double-developed in the double development area is equal to that of the toner image developed in the other development area, and the image of the toner image in the double development area and the other development area. The density difference can be reduced. Here, the developing doctor 21 is molded with a protrusion amount that has been confirmed in advance so that the image density of the toner image that has been double-developed in the double developing area and the toner image that has been developed in the other developing area are equal. . In the present embodiment, the shape of the developing doctor 21 provided facing the developing roller 11B disposed in the center portion of the developing rollers 11A, 11B, and 11C disposed in a staggered manner has been described. It goes without saying that the developing doctors provided facing the developing rollers 11A and 11C are similarly configured.
[0013]
Next, a third embodiment will be described. Since the configuration other than the shape of the developing doctor is the same as that described in the first embodiment, the description thereof will be omitted. FIG. 6 is a perspective view illustrating the shape of the developing doctor according to this embodiment. As described in the second embodiment, when the amount of protrusion of the developing doctor changes suddenly between the double developing area and the other developing areas and is excessive, that portion becomes a boundary line. Appear in the image. Therefore, as shown in FIG. 6, the developing doctor 22 according to the present embodiment is formed such that the protruding amount 22a of the double developing region is continuously larger than the protruding amount 22b of the other developing regions. As a result, the doctor gap in the double development area becomes continuously larger than the doctor gap in the other development areas, and the image density of the toner image on the photoreceptor 1 is abruptly increased at the boundary between the double development area and the other development areas. Can be suppressed. Then, it is possible to reduce the difference in image density of the toner image between the double development area and the other development areas. Here, the shape of the developing doctor 22 of the developing roller 11B disposed at the center of the developing rollers 11A, 11B, and 11C disposed in a staggered manner has been described. However, the developing roller 22 faces the developing rollers 11A and 11C. Needless to say, each of the provided development doctors is configured in the same manner.
[0014]
Next, a fourth embodiment will be described. Since the configuration other than the shape of the developing roller is the same as that described in the first embodiment, the description thereof will be omitted. FIG. 7 is a partially enlarged view for explaining the shape of the developing roller 23 according to the present embodiment. Depending on the developing ability, for example, the performance of the magnetic field generating means disposed inside the developing roller, the toner supply amount to the photoreceptor 1 can be adjusted only by adjusting the assembly of the developing doctors 14A to 14C as described in the first embodiment. It may be difficult to do. Therefore, in the present embodiment, the distance between the photoconductor 1 and the developing roller 23 is adjusted so as to be smaller in the double development region than in the other development regions. As shown in FIG. 7, the developing rollers 23A to 23C are formed such that the developing roller diameters 23aA to 23aC in the double developing area are larger than the developing roller diameters 23bA to 23bC in the other developing areas 17. Thereby, the doctor gap of the double developing area of each developing roller 23A-23C becomes smaller than the doctor gap of the other developing areas, and the amount of toner supplied to the photoreceptor 1 can be reduced in the double developing area. As a result, the image density of the toner image double-developed in the double development area is equal to that of the toner image developed in the other development area, and the image of the toner image in the double development area and the other development area. The density difference can be reduced.
[0015]
Next, a fifth embodiment will be described. Since the configuration other than the shape of the developing roller is the same as that described in the first embodiment, the description thereof will be omitted. FIG. 8 is a partially enlarged view for explaining the shape of the developing roller 24 according to this embodiment. As described in the fourth embodiment, when the diameter of the developing roller changes abruptly between the double developing area and the other developing areas and is excessive, that portion becomes a boundary line. Appears in the image. Therefore, as shown in FIG. 8, the developing rollers 24A to 24C according to this embodiment have the developing roller diameters 24aA to 24aC in the double developing area continuously larger than the developing roller diameters 24bA to 24bC in the other developing areas. It is formed to become. As a result, the doctor gap in the double development area is continuously larger than the doctor gap in the other development areas, and the image density of the toner image on the photoreceptor 1 is abruptly increased between the double development area and the other development areas. Can be suppressed. Then, it is possible to reduce the difference in image density of the toner image between the double development area and the other development areas.
[0016]
Next, a sixth embodiment will be described. Since the configuration other than the shape of the developing roller is the same as that described in the first embodiment, the description thereof will be omitted. FIG. 9 is a partially enlarged view illustrating the shape of the developing roller 25 according to the present embodiment. Due to the nature of the developer, in the double development region, the toner image on the photoconductor 1 developed by the developing rollers 25A and 25C arranged on the upstream side in the rotation direction of the photoconductor 1 is downstream in the rotation direction of the photoconductor 1. Therefore, the image density of the toner image formed on the photosensitive member 1 may be reduced. Therefore, in the present embodiment, the distance between the photosensitive member 1 and the developing roller 25 is adjusted so as to be larger in the double development area than in the other development areas. As shown in FIG. 9, the developing rollers 25A to 25C are formed such that the developing roller diameters 25aA to 25aC in the double developing area are smaller than the developing roller diameters 25bA to 25bC in the other developing areas. As a result, the doctor gap in the double development area becomes larger than the doctor gap in the other development areas, and the amount of toner supplied from the developing rollers 25A to 25C to the photoreceptor 1 can be increased in the double development area. As a result, the image density of the toner image double-developed in the double development area is equal to that of the toner image developed in the other development area, and the image of the toner image in the double development area and the other development area. The density difference can be reduced.
[0017]
Next, a seventh embodiment will be described. Since the configuration other than the shape of the developing roller is the same as that described in the first embodiment, the description thereof will be omitted. FIG. 10 is a partially enlarged view for explaining the shape of the developing roller 26 according to the present embodiment. As described in the sixth embodiment, when the diameter of the developing roller changes abruptly between the double developing area and the other developing areas and is excessive, that portion becomes a boundary line. Appears in the image. Therefore, as shown in FIG. 10, the developing rollers 26A to 26C according to the present embodiment have the developing roller diameters 26aA to 26aC in the double developing area continuously smaller than the developing roller diameters 26bA to 26bC in the other developing areas. It is formed to become. As a result, the doctor gap in the double development area is continuously larger than the doctor gap in the other development areas, and the image density of the toner image on the photoreceptor 1 is abruptly increased between the double development area and the other development areas. Can be suppressed. Then, it is possible to reduce the difference in image density of the toner image between the double development area and the other development areas.
[0018]
In the first to seventh embodiments, the doctor gap is adjusted in order to adjust the toner supply amount of the toner supplied from the developing roller to the photosensitive member so as to be different between the double developing region and the other developing region paths. The distance between the photosensitive member and the developing roller is adjusted (adjusting the diameter of the developing roller), but the present invention is not limited to this. In the case of using a two-component developer, in addition to the adjustment described above, the magnetic force distribution of the magnetic field generating means installed in the developing roller is used to adjust the amount of developer carried on the developing roller in the double developing region. May be adjusted. Further, when the one-component developer is supplied to the developing roller by the toner supply means, the toner supply means may be formed so that the toner supply capability is different between the double development area and the other development areas. For example, when a toner supply roller that rubs and supplies a one-component developer to the developing roller is used as the toner supply means, the friction coefficient between the surface portion of the toner supply roller corresponding to the double development region and the other portion is different. To form. Also, when using either a single-component developer or a two-component developer, the double-development area corresponds to this double-development area so that the developer carrying capacity or the conveyance capacity in the double-development area and other development areas are different. The surface portion of the developing roller may have a surface structure different from other portions. For example, the developing roller surface portion corresponding to the double developing region is formed so that the friction coefficient is smaller than that of other portions.
In the first to seventh embodiments, the description has been given of the application to the monochrome image copying machine. However, it goes without saying that the invention may be applied to a color image copying machine. Although the case where a drum-shaped latent image carrier and a developer carrier are used has been described, a belt-like latent image carrier and a developer carrier may be used.
[0019]
【The invention's effect】
According to the image forming apparatus of the present invention, adjacent ones of the plurality of developer carriers are located at different positions in the rotation direction of the developer carrier, and only the end portions of the adjacent ones are mutually in the width direction. In the image forming apparatus arranged side by side in the width direction so as to overlap, there is an excellent effect that the image density difference between the double development area and the other development areas can be reduced and the image density can be made uniform. is there.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a part of a copier according to a first embodiment.
FIG. 2 is a schematic configuration diagram showing a schematic configuration of a developing area of a developing device in the copier.
FIG. 3 is a perspective view showing a schematic configuration of a developing area of the developing device.
FIG. 4 is a front view showing a schematic configuration of a developing area of the developing device.
FIG. 5 is a perspective view illustrating the shape of a developing doctor of a developing device according to a second embodiment.
FIG. 6 is a perspective view illustrating the shape of a developing doctor of a developing device according to a third embodiment.
FIG. 7 is a partially enlarged view illustrating the shape of a developing roller of a developing device according to a fourth embodiment.
FIG. 8 is a partially enlarged view for explaining the shape of a developing roller of a developing device according to a fifth embodiment.
FIG. 9 is a partially enlarged view illustrating the shape of a developing roller of a developing device according to a sixth embodiment.
FIG. 10 is a partially enlarged view for explaining the shape of a developing roller of a developing device according to a seventh embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Photoconductor 4 Developing device 11,23,24,25,26 Developing roller 14,21,22 Developing doctor 15 Doctor gap 16 Double developing area 17 Other developing area

Claims

A rotatable latent image carrier carrying a latent image on the surface;
The width of the plurality of developer carriers in the rotational axis direction of the latent image carrier is shorter than the width of the latent image carrier, and the developer carried on the surface is rotated to rotate the latent image carrier. A plurality of developer carriers to be supplied to the surface of
The arrangement positions of the adjacent developer carriers in the rotation direction of the latent image carriers are different from each other, and the positions of the adjacent developer carriers in the width direction are such that only the ends overlap each other. Developer carriers are arranged side by side in the width direction,
At the developing area to supply the developer carried on the plurality of the developer carrying member surface to the latent image formed on said image bearing member, developing the latent image across the latent image bearing member throughout development In an image forming apparatus including the apparatus,
Image density is equivalent in the double development area where the development is performed in duplicate at the end of the adjacent developer carrying member where the positions in the width direction overlap with each other in the development area other than the double development area the image forming apparatus each developer carrying member is characterized by varying the supply amount of the developer supplied to the latent image carrier with a double developing region and other regions.

The image forming apparatus according to claim 1.
Current image-regulating member that the thickness Wins regulations for the developer conveyed toward the developing region is carried by the developer carrying member, at a predetermined interval between the surface of the developer carrying member Placed opposite ,
The distance between the developer carrying member and the developer regulating member, by causing different al between the double developing region and said another developing region, the supply amount of the double development region and other regions of the developing agent an image forming apparatus comprising Rukoto made different between.

The image forming apparatus according to claim 2.
The shape of the developer regulating member, by the end corresponding to the double-developing region is the protruding shape so as to approach to the development bearing surface side than the portion corresponding to the other developing areas, An image forming apparatus , wherein the interval is different between the double development area and the other development area .

The image forming apparatus according to claim 3.
An image forming apparatus, wherein the end portion of the developer restricting member has a shape such that the amount of protrusion continuously increases toward the outer side in the width direction .

The image forming apparatus according to claim 2 .
The shape of the upper Symbol surface of the developer carrying member, by a portion corresponding to the double-developing region is the protruding shape so as to approach to the developer regulating member side than the portion corresponding to the other developing areas The image forming apparatus is characterized in that the interval is different between the double development area and the other development area .

The image forming apparatus according to claim 5.
Image forming characterized in that the surface shape of the portion corresponding to the double development region of the developer carrying member is such that the protruding amount continuously increases toward the outside of the end of the corresponding developer regulating member. apparatus.

The image forming apparatus according to claim 2 .
The shape of the upper Symbol surface of the developer carrying member, by a portion corresponding to the double-developing region is a concave shape as to be separated from the developer regulating member than the portion corresponding to the other developing areas, An image forming apparatus , wherein the interval is different between the double development area and the other development area .

The image forming apparatus according to claim 7.
The image forming method is characterized in that the surface shape of the portion corresponding to the double development region of the developer carrying member is such that the dent amount continuously increases toward the outer end of the corresponding developer regulating member. apparatus.