JP3639037B2 - Color image forming method and color image forming apparatus - Google Patents

Color image forming method and color image forming apparatus Download PDF

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JP3639037B2
JP3639037B2 JP10218096A JP10218096A JP3639037B2 JP 3639037 B2 JP3639037 B2 JP 3639037B2 JP 10218096 A JP10218096 A JP 10218096A JP 10218096 A JP10218096 A JP 10218096A JP 3639037 B2 JP3639037 B2 JP 3639037B2
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JPH09292751A (en
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博之 松代
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Ricoh Co Ltd
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Ricoh Co Ltd
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Description

【０００１】
【発明の属する技術分野】
本発明は、中間転写体上にカラーの重ねトナー像を得て、この重ねトナー像を転写紙に一括転写する方式のカラー画像形成装置およびカラー画像形成方法に関する。
【０００２】
【従来の技術】
従来より電子写真法を適用して多色再現を可能にするカラー画像形成装置においては、色分解光像を潜像担持体に露光し、形成された各潜像を各々色分解光の補色のトナーで現像し、得られた複数のトナー像を同一中間転写体上に重ね合わせて一次転写してカラー像を形成し、そのカラー像を静電転写により転写紙へ二次転写してカラーが像を得るフルカラー複写機などのカラー画像形成装置が知られている。
【０００３】
一方、モノクロ複写機やモノクロプリンターにおいて、トナー像を静電潜像担持体としての感光体から転写紙へ静電転写するための転写部材として、転写紙の搬送性に優れる転写ローラ方式が知られている。そこで、前述のフルカラー複写機においても、中間転写体上のトナー像を転写紙へ静電転写するために、転写ローラを用いることができる。この二次転写の手段である転写ローラを転写部材と称する。
【０００４】
前記カラー画像形成装置にこのような転写ローラを使用したカラー画像形成装置の例として、静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための、前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置として特開平６−１６７８４２に開示された技術がある。
【０００５】
【発明が解決しようとする課題】
前記公知技術では、中間転写体上には、複数の色のトナー像が順次感光体から中間転写体に転写されてくるため、この転写が行なわれている一次転写の間は転写ローラの汚れ防止のため、該転写ローラを中間転写体から離間させた位置に退避させておき、中間転写体から転写紙への転写である二次転写を行なうときには、転写ローラを転写紙を間に挟んで中間転写体と当接する位置に移動させる必要がある。
【０００６】
このように、転写部材としての転写ローラを中間転写体に接離させると、特に、中間転写体の駆動およびその駆動系が感光体ともつながっている場合には感光体の駆動にも影響を与え、上記接離に伴う光書き込み中や一次転写中に中間転写体に対して転写ローラの接離を行なうと、負荷変動により画像上に横スジなどの不具合が発生してしまう。また、クリーニング部材についても、これが中間転写体に対して接離自在に構成されていることから、前記転写ローラと同様に、中間転写体や感光体の駆動に影響を与え、上記接離に伴う負荷変動により画像上に横スジなどの不具合を発生する要因となる。
【０００７】
そこで、請求項１〜請求項４に記載の発明は、中間転写体に対して接離する部材が、この接離に伴い該中間転写体あるいは感光体に負荷変動を与え画像形成に悪影響を与えるのを回避することのできるカラー画像形成方法およびカラー画像形成装置を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明は、前記目的を達成するため、
（１） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置を用いて行なうカラー画像形成方法において、カラー画像の連続プリント時に、前記転写部材および前記クリーニング部材の前記中間転写体に対する接触動作を、最終版の一次転写終了後で、かつ、次のプリントの第１版の露光工程開始以前に行ない、かつ前記転写部材および前記クリーニング部材の前記中間転写体からの離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に行なうこととした（請求項１）。
【０００９】
（２） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置において、カラー画像の連続プリント時に、前記転写部材および前記クリーニング部材の前記中間転写体に対する接触動作を、最終版の一次転写終了後で、かつ、次のプリントの第１版の露光工程開始以前に行ない、かつ前記転写部材および前記クリーニング部材の前記中間転写体からの離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に行なわせる制御手段を有することとした（請求項２）。
【００１０】
（３） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置を用いて行なうカラー画像形成方法において、カラー画像の連続プリント時に、前記転写部材および前記クリーニング部材の前記中間転写体に対する接触動作を、最終版の一次転写終了後で、かつ、次のプリントの第１版の露光工程開始以前に同時に行ない、かつ前記転写部材および前記クリーニング部材の前記中間転写体からの離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に同時に行なうこととした（請求項３）。
【００１１】
（４） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置において、カラー画像の連続プリント時に、前記転写部材および前記クリーニング部材の前記中間転写体に対する接触動作を、最終版の一次転写終了後で、かつ、次のプリントの第１版の露光工程開始以前に同時に行ない、かつ前記転写部材および前記クリーニング部材の前記中間転写体からの離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に同時に行なわせる制御手段を有することとした（請求項４）。
【００１２】
なお、以下のように構成することができる。
（ａ） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための、前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置を用いて行なうカラー画像形成方法において、カラー画像の連続プリント時に、前記クリーニング部材の前記中間転写体に対する接触動作を、最終版の一次転写終了後でかつ、次のプリントの第１版の露光工程開始以前に行なうカラー画像形成方法。
【００１３】
（ｂ） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための、前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置において、カラー画像の連続プリント時に、前記クリーニング部材の前記中間転写体に対する接触動作を、最終版の一次転写終了後でかつ、次のプリントの第１版の露光工程開始以前に行なわせる制御手段を有するカラー画像形成装置。
【００１４】
（ｃ） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための、前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置を用いて行なうカラー画像形成方法において、カラー画像の連続プリント時に、前記クリーニング部材の前記中間転写体に対する離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に行なうカラー画像形成方法。
【００１５】
（ｄ） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための、前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置において、カラー画像の連続プリント時に、前記クリーニング部材の前記中間転写体に対する離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に行なわせる制御手段を有するカラー画像形成装置。
【００１６】
（ｅ） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための、前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置を用いて行なうカラー画像形成方法において、カラー画像の連続プリント時に、前記転写部材の前記中間転写体に対する接触動作と前記クリーニング部材の前記中間転写体に対する接触動作とを同時に、最終版の一次転写終了後でかつ次のプリントの第１版の露光工程開始以前に行なうカラー画像形成方法。
【００１７】
（ｆ） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための、前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置において、カラー画像の連続プリント時に、前記転写部材の前記中間転写体に対する接触動作と前記クリーニング部材の前記中間転写体に対する接触動作とを同時に、最終版の一次転写終了後でかつ次のプリントの第１版の露光工程開始以前に行なわせる制御手段を有するカラー画像形成装置。
【００１８】
（ｇ） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための、前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置を用いて行なうカラー画像形成方法において、カラー画像の連続プリント時に、前記転写部材の前記中間転写体に対する離間動作と前記クリーニング部材の前記中間転写体に対する離間動作とを同時に、第１版の露光工
程終了後で第２版の露光工程開始以前に行なうカラー画像形成方法。
【００１９】
（ｈ） 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための、前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置において、カラー画像の連続プリント時に、前記転写部材の前記中間転写体に対する離間動作と前記クリーニング部材の前記中間転写体に対する離間動作とを同時に、第１版の露光工程終了後で第２版の露光工程開始以前に行なわせる制御手段を有するカラー画像形成装置。
【００２０】
【発明の実施の形態】
（一）各請求項記載の発明に共通する例
本発明の実施に適する画像形成装置の一例であるフルカラープリンタを示す図１において、潜像担持体としてのベルト状の感光体１は帯電チャージャ４により一様に帯電された後、レーザ光学装置５により画像情報に基づき走査露光されて表面に静電潜像が形成される。ここで、露光する画像情報は、所望のフルカラー画像をイエロー、マゼンタ、シアン、および黒の色情報に分解した単色の画像情報である。形成された静電潜像は、イエロー、マゼンタ、シアンのカラートナーを収容した３個の現像器を具備した回転型のカラー現像装置６および、該カラー現像装置６とは別に設けてある黒のトナーを収容した黒現像器を具備した現像装置７とにより各々所定のイエロー、マゼンタ、シアン、および黒トナーで重ね現像され、感光体１上に複数の色の重ねトナー画像が形成される。
【００２１】
前記カラー現像装置６および現像装置７は各々所定の位置で前記感光体１と近接あるいは接触する各現像ローラを備え、感光体１上の潜像を非接触であるいは接触状態で顕像化する現像機能を有している。符号１０は中間転写体たる中間転写ベルトを示し、該中間転写ベルト１０は回動ローラ１１、１２の間に架設され、これら回動ローラ１１、１２の駆動により回動される。
【００２２】
感光体１は、回動ローラ２、３の間に架設され、回動ローラの駆動により図中矢印Ａ方向に回転する。回動ローラ１１または回動ローラ１２と回動ローラ２または回動ローラ３とは、共通の駆動モータにより駆動されるようにギヤ、プーリなど適宜の連結手段により連結されていて、感光体１と中間転写ベルト１０とが接触する一次転写位置Ｅにおいて相対速度がゼロとなるように同期して同一方向に回動されるようになっている。
【００２３】
感光体１は帯電チャージャ４により一様に帯電される。次いで、レーザ光学装置５からの色毎の光により露光され、後述する現像装置６または現像装置７により現像される毎に、該感光体１と同期して図中矢印Ｂ方向に回転する中間転写ベルト１０上に、イエロー、マゼンタ、シアンおよび黒の単色毎に、中間転写ベルト１０の内側に設けられた一次転写バイアスブラシ１３に適正な転写バイアス電圧が印加されることにより、順次転写されていき、重ね転写される。
【００２４】
すなわち、中間転写ベルト１０上には、第１版としてのイエロートナー像の上に第２版としてのマゼンタトナー像、その上に第３版としてのシアントナー像、さらにその上に第４版としての黒トナー像が重ねられてカラートナー像が形成される。
【００２５】
中間転写ベルト１０上に重ね合わされたイエロー、マゼンタ、シアンおよび黒のトナーによる重ねトナー画像は、給紙カセット８から給紙ローラ９、レジストローラ６０を経て転写部へ搬送された転写紙上に転写ローラ１４により一括転写される。転写終了後、転写紙は定着装置１８により定着されてフルカラー画像が完成する。
【００２６】
符号１５は感光体１のクリーニングブレード１５Ａを含む廃棄トナー回収容器、符号１６は中間転写ベルト１０のクリーニング装置をそれぞれ示し、該クリーニング装置１６のクリーニングブレード１６Ａは画像形成中には中間転写ベルト１０の表面より離間した位置に保たれ、トナー像の紙転写後のクリーニング時のみ図示のように中間転写ベルト１０の表面に圧接される。
【００２７】
図２は、図１に示したカラー画像形成装置の一部であるカラー現像装置の例を示している。図２において、感光体１の近傍には、カラー現像装置としての回転型（リボルバー型、ロータリー型ともいう。）の現像装置６とは別に黒トナーによる現像器を収容した黒現像器７が配置されている。この現像装置６においては、回転体を形成するケーシング２０が回転中心Ｏを中心に回転自在に設けられ、ケーシング２０は図示を省略した駆動機構により矢印Ｃ方向に回転される。また、上記ケーシング２０はハッチングを付して示すように現像装置を３分割するような形状をしていて、これにより、イエロートナーによる現像器２２−Ｙ，マゼンタトナーによる現像器２２−Ｍ，シアントナーによる現像器２２−Ｃが形成されている。
【００２８】
図３は、図２に示した現像装置６内の一つの現像器２２−Ｙの現像ローラ２３Ｙが感光体１上の所定の現像位置にある状態を示している。各現像器２２−Ｙ，２２−Ｍ，２２−Ｃにはそれぞれ、現像剤搬送部材としての円筒状の現像ローラ２３Ｙ，２３Ｍ，２３Ｃが設けられている。これらの各現像ローラ２３Ｙ，２３Ｍ，２３Ｃは、上記ケーシング２０に設けられた開口部からその一部が外部に露出するように配置されていて、現像装置６は色情報に同期して図中矢印Ｃ方向に回転し、対応する静電潜像を現像する。
【００２９】
本例における現像装置６の現像器２２−Ｙ，２２−Ｍ、２２−Ｃおよび現像装置７の現像器では非磁性一成分現像剤が用いれ、前記したように、イエロー、マゼンタ、シアン、黒の各トナーが収納されていて、現像装置６については回転中心Ｏを中心にして所定の現像器が所定の現像位置に位置するように回転して、該当する現像器のトナーにより順次感光体ベルト１上に形成された静電潜像を現像し、上述のように各トナー像を中間転写ベルト１０上に重ね合わせ、転写紙上に一括転写することにより、フルカラー画像を形成する。
【００３０】
図４は現像装置７の現像ローラ２３が感光体１上の所定の現像位置にある状態を示している。現像装置７は現像容器４１内に黒トナーを収容するタイプの現像器からなり、トナーエンド時を現像器の寿命とし交換時期とする、いわゆる現像カートリッジとして一体的に形成されている。この現像装置７においても現像装置６の各現像器２２−Ｙ，２２−Ｍ，２２−Ｃなどの現像ローラ２３Ｙ，２３Ｍ，２３Ｃなどと同様に現像ローラ２３は感光体１と所定の線速比をもって矢印Ａで示す感光体１の移動方向と同方向に移動するように、つまり連れ回り回転するように、感光体１に対向して配設されている。現像ローラ２３の上方には、発泡ポリウレタンなどの弾性体からなる供給ローラ３１が摺擦部において現像ローラ２３と同方向に、所定の線速比をもって摺擦、連れ回り回転するように設けられている。さらに、厚さ０．１ｍｍ程度のステンレス薄板やまたはウレタンゴムなどの弾性体からなる薄層ブレード３２が、その一端が現像ローラ２３に接するように設けられている。現像容器４１内には、薄層ブレード３２近傍のトナーを撹拌する複数の羽根状部を有するパドル４２が設けられている。また、供給ローラ３１および現像ローラ２３側にトナーを搬送、撹拌する第１のアジテータ４３と第２のアジテータ４４が設けられている。
【００３１】
現像装置７は図示しない加圧手段により、感光体１に対して接離する方向である矢印Ｄ、Ｄ’で示す方向に可動状態に案内支持されるとともに離間する方向である矢印Ｄ’の向きに加圧されており、カム４５の回転により現像ローラ２３と感光体１とが接離される。
【００３２】
図１に示したフルカラープリンタについて、中間転写ベルト１０に対する転写ローラ１４の接離制御および、中間転写ベルト１０に対するクリーニグブレード１６Ａの接離制御のための各手段について説明する。
図１において中間転写ベルト１０の外周面であって画像形成領域外の任意の部位と対向するようにして、マーク検知センサ５０が設けられている。また、このマーク検知センサ５０による検知可能領域にて移動する中間転写ベルト１０上には、このマーク検知センサ５０により読み取ることができるマークが印されている。このマーク検知センサ５０によるマークの読み取り信号は、ＣＰＵ（中央処理装置）５１に入力されるようになっている。ＣＰＵ５１からは接離手段５２、接離手段５３にそれぞれ出力信号が出力されるようになっている。
【００３３】
接離手段５２は、例えば、転写ローラ１４を収めたケーシングなどに連結されたソレノイドからなり、このソレノイドと上記ケーシングとは、リンクなどにより連結されている。この連結手段を便宜上、図１に二重線で示す。このケーシングは転写ローラ１４が中間転写ベルト１０に対して接離する方向に摺動自在に支持されていて、かつ、当接する向きに弾性手段により付勢されていて当接している。上記ソレノイドにオン信号が入力されると上記ケーシングはソレノイドにより引かれて移動し、転写ローラ１４は中間転写ベルト１０から離間した状態となる。上記ソレノイドにオフ信号が入力されれば、転写ローラ１４は中間転写ベルト１０に対して当接状態となる。
【００３４】
上記接離手段５２と転写ローラ１４との関係と全く同様の構成が、接離手段５３とクリーニングブレード１６Ａにも施されている。これにより、接離手段５３を構成するソレノイドに、ＣＰＵ５１からオン信号が出力されるとクリーニングブレード１６Ａは中間転写ベルト１０から離間した状態となるし、オフ信号が出力されると中間転写ベルト１０に接触した状態となる。
【００３５】
なお、上記の説明において、ソレノイドに代えて、半回転クラッチや、ロータリーソレノイドなどを使用して、これらの駆動により転写ローラ１４を収めたケーシングや、クリーニングブレード１６Ａを収めたケーシングを移動して、中間転写ベルト１０に対する転写ローラ１４の接離制御や、中間転写ベルト１０に対するクリーニングブレード１６Ａの接離制御をすることもできる。
【００３６】
ＣＰＵ５１における制御の内容の例を図６に示す。図６において、ステップＳ１で、プリントスタート指令があると、所定のシーケンスに従い、図１に示すプリンタが駆動を開始し、画像形成のプロセスが進行する。ステップＳ２でマークの検知の有無が判断され、中間転写ベルト１０の回転によりマークが検知されると、この検知信号がＣＰＵ５１に取り込まれ、ステップＳ３で連続プリントモードか否かが判断される。連続プリントモードでなければ、ステップＳ４に進み、上記マークの検知時点を基準として１枚プリントが実行される。
【００３７】
ステップＳ３で連続プリントモードであると判断されると、ステップＳ５に進み、上記マークの検知時点を基準として、連続プリントシーケンスが実行される。この連続プリントシーンケンスの具体的な内容は、後述する図５に即した説明のとおりである。ステップＳ５において、１枚のプリントが終える毎に、ステップＳ６を経てステップＳ２に進む工程が、指令された枚数のプリントが終わるまで繰り返される。
【００３８】
図１において、一次転写バイアスブラシ１３が設けられた部位に対応する中間転写ベルト１０の外周面位置に感光体１が接触していて、この部位である一次転写位置Ｅにて一次転写が行なわれる。この一次転写位置Ｅを基点として中間転写ベルトが移動する矢印Ｂで示す向きに、転写ローラ１４が中間転写ベルト１０に接触している二次転写位置Ｆまでの距離は、出力可能な転写紙のうち、その送り方向での長さが最大のものの、その最大の転写紙の送り方向での長さ（以下、最大転写紙長という。）以上となるように、中間転写ベルト１０を設定し、かつ該中間転写ベルト１０のまわりに、感光体１、一次転写バイアスブラシ１３、転写ローラ１４を配置している。
【００３９】
具体的には、出力可能な最大転写紙長をＡ４縦（紙の長手方向を送り方向とする場合。）の２９７ｍｍとした場合、上記一次転写位置Ｅから二次転写位置Ｆまでの中間転写ベルト１０の外周面に沿う距離は、３０１．１ｍｍに設定する。
【００４０】
このように配置および設定を行なうことにより、一次転写位置ＥでＡ４縦サイズのトナー像の第４版（黒トナー像）が全て感光体ベルト上から中間転写ベルト上へ転写されたとき、トナー像の先端は未だ二次転写位置へ到達していないこととなる。したがって、Ａ４縦サイズのトナー像の第４版（黒トナー像）が全て感光体ベルト上から中間転写ベルト上へ転写された後に、転写ローラ１４を、中間転写ベルト１０から退避した位置から中間転写ベルト１０に接触する位置へ転写紙を挟むように移動させ、この状態の下で二次転写を行なうことができる。
【００４１】
このように配置および動作させることにより、転写ローラ１４の中間転写ベルト１０に対する接触動作を一次転写終了後に行なうことができ、転写ローラ１４が転写ベルト１０に接触して負荷変動を生じさせることがあっても、一次転写中の中間転写ベルト１０および感光体１の駆動には影響を与えないので画像上での横スジなどの発生を回避できる。
【００４２】
（二）例１
図１乃至図５を適宜参照しつつ説明する。
カラー画像の形成に際しては、まず、感光体１の駆動が行なわれ、それと同時に帯電チャージャ４により帯電が行なわれる。次に、レーザ光学装置５からの光により露光工程（光書き込み）が行なわれ、感光体１上に第１版イエロー用の静電潜像が形成される。この静電潜像が現像位置６の現像位置に移動してくると、現像器２２−Ｙによりイエロートナーによるカラー現像が行なわれる。このイエロートナー像は、一次転写バイアスブラシ１３によるバイアス印加により、一次転写位置Ｅにて中間転写ベルト１０上に転写される。
【００４３】
イエロートナーによる現像後、現像装置６が回転駆動機構により回転し、マゼンタトナーによる現像器２２−Ｍが感光体１上の現像位置に対向する。一方、中間転写ベルト１０上のイエロートナー像に同期するように感光体１上には第２版マゼンタ用の静電潜像が形成され、このマゼンタの静電潜像が現像位置に移動してくるのと同期して現像器２２−Ｍによりマゼンタによるカラー現像が行なわれる。そして、マゼンタトナー像は前記イエロートナー像と同様に一次転写バイアスブラシ１３のバイアス印加により、一次転写位置Ｅにて中間転写ベルト１０上に重ね転写される。ここまでは、図５において省略した。図５では、次いで行なわれるカラー現像、一次転写の各工程が同様に実線で示されている時間の間、行なわれる。第３版（シアン）のカラー現像後、現像装置６は回転駆動機構により回転し、現像器２２−Ｙ，２２−Ｍ，２２−Ｃのいずれの現像器も感光体１と対向しない基準位置、例えば、図１、図２、図４に示す位置に停止される。
【００４４】
最後に、中間転写ベルト１０上の第１版（イエロー）、第２版（マゼンタ）、第３版（シアン）の重ねトナー像に同期するように第４版（黒）の静電潜像が形成され、その静電潜像が現像装置７が配置された現像位置に移動してくるのと同期して、現像装置７がカム４５の回転により感光体１上の現像位置に移動し、黒現像が行なわれる。そして、この黒現像による黒トナー像も同様に中間転写ベルト１０上の重ねトナー像に重ね転写される。
【００４５】
黒トナー像の一次転写が全て終了後、Δｔ１の時間の間に転写ローラ１４が中間転写ベルト１０から離間退避した位置から中間転写ベルト１０に接触する二次転写位置Ｆへ転写紙を挟むように移動し、転写紙への二次転写が行なわれる。
図５に示すタイミングチャートは連続プリント時のものであり、前プリントの第４版（黒）のトナー像の一次転写が全て終了（ａ点）後、次プリントの第１版（イエロー）の光書き込み開始（ｂ点）が行なわれる。
【００４６】
上記したように、カラー画像の連続プリント時に、転写ローラ１４の中間転写ベルト１０に対する接触動作を、最終版の一次転写終了後で、かつ、次のプリントの第１版の露光工程開始以前に行なわせるという動作は、図１に示した中間転写ベルト１０上のマーク、マーク検知センサ５０、接離手段５２およびこの接離手段を作動させるＣＰＵ５１などの働きにより行なわれる。よって、これらの部材が請求項２に記載した発明における制御手段の例となる。ここで、ＣＰＵ５１は接離手段５２を制御する機能を有していれば十分であり、必ずしも接離手段５３を制御する機能を有している必要はない。
【００４７】
このような制御手段の働きにより、図５で説明したように、転写ローラ１４の中間転写ベルト１０に対する接触動作が、前プリントの最終版（第４版）の一次転写後であってかつ、次プリントの第１版（イエロー）の光書き込み開始（ｂ点）以前に行なわれる。このように、二次転写工程に含まれる転写ローラ１４の接触動作を一次転写終了（ａ点）後でかつ次プリントの第１版（イエロー）の光書き込み開始（ｂ点）以前、つまりΔｔ１の時間内のｃ点にて行なうことにより、一次転写中および次プリントの光書き込み中に、中間転写ベルトおよび感光体ベルトの駆動に影響を与えることなく、画像上に横スジなどが発生するのを防止できる。
【００４８】
二次転写工程の開始は、▲１▼二次転写位置への転写紙先端の進入、▲２▼二次転写位置での中間転写ベルトへの転写ローラの接触、▲３▼二次転写位置への中間転写ベルトに担持されたトナー像の先端の進入、の３つの動作から構成される。これら３つの動作の理想的なタイミングとしては、上記▲１▼、▲２▼、▲３▼、の３動作が同時に行なわれることである。但し、必ず同一タイミングというのは、転写紙の紙種による微小スリップの発生という、精密制御しきれない要因のあるので、少なくとも▲１▼→▲２▼→▲３▼の順であることが必要である。これら一連の動作に要する時間は、▲１▼〜▲３▼までの時間が、転写紙の先端白抜け幅の許容値４．２ｍｍを考慮すると０．０４ｓｅｃ程度である。この際、▲１▼または▲３▼と同時、または▲２▼の動作は▲１▼と▲３▼の間であればどのタイミングでもよい。
【００４９】
なお、本例の画像形成装置では、最大使用転写紙サイズをＡ４サイズとし、転写紙搬送方向での最大転写紙長さはＡ４縦送りで２９７ｍｍである。最大使用転写紙サイズがＡ４縦送りの場合、Δｔ１＝０．１８ｓｅｃとなり、このとき、ａ点からｃ点までの時間は０．０２ｓｅｃである。
また、最大使用転写紙サイズが、ダブルレター横の２枚取り（米国レターサイズ２１６ｍｍ×２＋紙間４０ｍｍ＝４７２ｍｍ）で、このサイズの場合には、Δｔ１＝０．２１ｓｅｃ、ａ点からｃ点までの時間は０．０３ｓｅｃである。
さらに、最大使用転写紙サイズをＡ３サイズとすれば当然、時間Δｔ１も大きくなり、Δｔ１＝０．７５ｓｅｃ、ａ点からｃ点までの時間は０．５７ｓｅｃである。
【００５０】
（三）例２
図５において、二次転写工程が開始（ｃ点）された後に、次プリントの第１版（イエロー）の光書き込みが開始（ｂ点）され、この光書き込み工程の終了（ｄ点）と略同時に前プリントの二次転写工程が終了（ｅ点）する。本例では、次プリントの第１版（イエロー）の光書き込み工程の終了（ｄ点）後に中間転写ベルト１０に対する転写ローラ１４の離間動作を行なう。そして、この転写ローラ１４の中間転写ベルト１０からの離間動作後に次プリントの第２版（マゼンタ）の光書き込みを開始（ｆ点）する。
【００５１】
上記したように、カラー画像の連続プリント時に、転写ローラ１４の中間転写ベルト１０からの離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に行なわせるという動作は、図１に示した中間転写ベルト１０上のマーク、マーク検知センサ５０、接離手段５２およびこの接離手段を作動させるＣＰＵ５１などの働きにより行なわれる。よって、これらの部材が発明における制御手段の例となる。ここで、ＣＰＵ５１は接離手段５２を制御する機能を有していれば十分であり、必ずしも接離手段５３を制御する機能を有している必要はない。
【００５２】
このような制御手段の働きにより、図５で説明したように、転写ローラ１４の中間転写ベルト１０からの離間動作を第１版の露光工程終了後（光書き込み終了後）（ｄ点）で第２版の露光工程開始（光書き込み開始）（ｆ点）以前、つまり図５に示すΔｔ２の時間の間に行なうことにより転写ローラ１４が中間転写ベルト１０から離間することに伴う中間転写ベルト１０の負荷変動があっても、光書き込み中ではないので、中間転写ベルト１０および感光体１の負荷変動により画像上に横スジなどが発生するのを回避できる。
【００５３】
（四）例３
図５において、まず感光体１の駆動が行なわれ、それと同時に帯電チャージャ４により帯電が行なわれる。次に、露光工程において光書き込みが行なわれ、感光体１上にイエローの静電潜像が形成される。
この静電潜像が現像位置に移動してくると、イエローの現像器２２−Ｙにより現像が行なわれる。そのトナー像は一次転写位置Ｅにて、一次転写バイアスブラシ１３によるバイアス印加により、中間転写ベルト１０上に一次転写される。次に、現像装置６が回転駆動装置により回転させられ、マゼンタの現像器２２−Ｍが感光体１上の所定の現像位置に対向するようになる。さらに中間転写ベルト１０上のトナー像に同期するように感光体１上にマゼンタの静電潜像が形成され、この静電潜像が現像位置に移動してくるのと同期して現像器２２−Ｍにより現像が行なわれる。そしてマゼンタトナー像は、一次転写バイアスブラシ１３によるバイアス印加により、中間転写ベルト上に重ね転写される。ここまでは、図５において省略した。図５では、次いで行なわれる第３版（シアン）画像の光書き込
み、カラー現像、一次転写の各工程が同様に実線で示される時間の間、行なわれる。第３版（シアン）の現像後、現像装置６は回転駆動機構により回転させられ、現像器２２Ｙ，２２Ｍ，２２Ｃのいずれの現像器も感光体１と対向しない基準位置、例えば図１、図２、図４に示す位置に停止される。
【００５４】
最後に、中間転写ベルト１０上の第１版（イエロー）、第２版（マゼンタ）、第３版（シアン）の重ねトナー像に同期するように第４版（黒）の静電潜像が、現像装置７が配置された現像位置に移動してくるのと同期して、現像装置７がカム４５の回転により感光体１上の現像位置に移動し、黒現像が行なわれる。そしてこの黒現像による黒トナー像も同様に中間転写ベルト上の重ねトナー像に重ね転写される。
【００５５】
黒トナー像の一次転写が全て終了後、Δｔ１の時間の間に転写ローラ１４が中間転写ベルト１０から離間退避した位置から中間転写ベルト接触する二次転写位置Ｆへ転写紙を挟むように移動し、転写紙への二次転写が行なわれる。
【００５６】
さらに黒トナー像の一次転写が全て終了後、中間転写ベルト１０のクリーニング部材であるクリーニングブレード１６Ａが中間転写ベルト１０から退避した位置から中間転写ベルト１０に接触する位置へ移動し、中間転写ベルト１０上の残トナーのクリーニングが行なわれる。
【００５７】
図５に示すタイミングチャートは連続プリント時の状態を示すものであり、前プリントの第４版（黒）トナー像の一次転写が全て終了（ａ点）後、次プリントの第１版（イエロー）の光書き込みが開始（ｂ点）される。本例では、クリーニングブレード１６Ａの中間転写ベルト１０に対する接触動作は第４版（黒）の一次転写終了（ａ点）後であって、かつ、次プリントの第１版（イエロー）の光書き込み開始（ｂ点）以前つまり、図５におけるΔｔ１の時間内に行なわれる。
【００５８】
上記したように、カラー画像の連続プリント時に、前記クリーニングブレード１６Ａの中間転写ベルト１０に対する接触動作を、最終版の一次転写終了後でかつ、次のプリントの第１版の露光工程開始以前に行なうという動作は、図１に示した中間転写ベルト１０上のマーク、マーク検知センサ５０、接離手段５２およびこの接離手段を作動させるＣＰＵ５１などの働きにより行なわれる。よって、これらの部材が発明における制御手段の例となる。ここで、ＣＰＵ５１は接離手段５３を制御する機能を有していれば十分であり、必ずしも接離手段５２を制御する機能を有している必要はない。
【００５９】
このような制御手段の働きにより、図５で説明したように、クリーニングブレード１６Ａの中間転写ベルト１０に対する接触動作を一次転写終了（ａ点）後でかつ、次プリントの第１版（イエロー）の光書き込み開始（ｂ点）以前に行なうことにより、クリーニングブレード１６Ａが中間転写ベルト１０に接触することによって中間転写ベルト１０および感光体１の負荷変動が生じても、一次転写中および次プリントの光書き込み中ではないので、中間転写ベルトおよび感光体ベルトの負荷変動があっても画像上に横スジなどの不具合が発生することがない。
【００６０】
（五）例４
図５において、中間転写ベルト１０にクリーニングブレード１６Ａが接触することにより中間転写ベルト１０のクリーニング工程が開始された後に、次プリントの第１版（イエロー）の光書き込みが開始（ｂ点）され、この光書き込み工程の終了（ｄ点）と略同時に中間転写ベルト１０からクリーニングブレード１６Ａが離間することによって中間転写ベルトのクリーニング工程が終了する。本例では、次プリントの第１版（イエロー）の光書き込みが終了（ｄ点）後にクリーニングブレード１６Ａを中間転写ベルト１０から離間させる。さらに、クリーニングブレード１６Ａの中間転写ベルト１０からの離間動作後に次プリントの第２版（マゼンタ）の光書き込みを開始（ｆ点）する。
【００６１】
上記したように、カラー画像の連続プリント時に、クリーニングブレード１６Ａの中間転写ベルト１０に対する離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に行なうという動作は、図１に示した中間転写ベルト１０上のマーク、マーク検知センサ５０、接離手段５２およびこの接離手段を作動させるＣＰＵ５１などの働きにより行なわれる。よって、これらの部材が発明における制御手段の例となる。ここで、ＣＰＵ５１は接離手段５３を制御する機能を有していれば十分であり、必ずしも接離手段５２を制御する機能を有している必要はない。
【００６２】
このような制御手段の働きにより、中間転写ベルトのクリーニング部材の離間動作を次プリントの第１版（イエロー）の露光工程（光書き込み）終了（ｄ点）後で第２版（マゼンタ）の光書き込み開始（ｆ点）以前、つまり時間Δｔ２の間に行なうことにより、クリーニングブレード１６Ａが中間転写ベルト１０から離間することによって中間転写ベルト１０および感光体１の負荷変動が生じても光書き込み中ではないので、中間転写ベルトおよび感光体の負荷変動があっても画像上に横スジなどの不具合が発生することがない。
【００６３】
（六）例５
図５において、まず感光体１の駆動が行なわれ、それと同時に帯電チャージャ４により帯電が行なわれる。次に、露光工程において光書き込みが行なわれ、感光体１上にイエローの静電潜像が形成される。
この静電潜像が現像位置に移動してくると、イエローの現像器２２−Ｙにより現像が行なわれる。そのトナー像は一次転写位置Ｅにて、一次転写バイアスブラシ１３によるバイアス印加により、中間転写ベルト１０上に一次転写される。次に、現像装置６が回転駆動装置により回転し、マゼンタの現像器２２−Ｍが感光体１上の現像位置に対向するようになる。さらに中間転写ベルト１０上のトナー像に同期するように感光体１上にマゼンタの静電潜像が形成され、この静電潜像が現像位置に移動してくるのと同期して現像器２２−Ｍにより現像が行なわれる。そしてマゼンタトナー像は、一次転写バイアスブラシ１３によるバイアス印加により、中間転写ベルト上に重ね転写される。ここまでは、図５において省略した。
【００６４】
図５では、次いで行なわれる第３版（シアン）画像の光書き込み、カラー現像、一次転写の各工程が同様に実線で示される時間の間、行なわれる。第３版（シアン）の現像後、現像装置６は回転駆動機構により回転し、現像器２２Ｙ，２２Ｍ，２２Ｃのいずれの現像器も感光体１と対向しない基準位置、例えば図１、図２、図４に示す位置に停止される。
【００６５】
最後に、中間転写ベルト１０上の第１版（イエロー）、第２版（マゼンタ）、第３版（シアン）の重ねトナー像に同期するように第４版（黒）の静電潜像が、現像装置７が配置された現像位置に移動してくるのと同期して、現像装置７がカム４５の回転により感光体１上の現像位置に移動し、黒現像が行なわれる。そしてこの黒現像による黒トナー像も同様に中間転写ベルト上の重ねトナー像に重ね転写される。
【００６６】
黒トナー像の一次転写が全て終了後、Δｔ１の時間の間に転写ローラ１４が中間転写ベルト１０から離間退避した位置から中間転写ベルト接触する二次転写位置Ｆへ転写紙を挟むように移動し、転写紙への二次転写が行なわれる。この転写ローラ１４の中間転写ベルト１０に対する接触動作と同時に、クリーニングブレード１６Ａが中間転写ベルト１０から退避した位置から中間転写ベルトに接触する位置へ移動し、中間転写ベルト１０上の残トナーのクリーニングが行なわれる。
【００６７】
図５に示す連続プリントにおいて、前プリントの第４版（黒）トナー像の一次転写が全て終了（ａ点）後、Δｔ１の時間をおいてｂ点より次プリントの第１版（イエロー）の光書き込みが行なわれる。図５に示すように本例のカラー画像形成方法では、前プリントの第４版（黒）トナー像の一次転写が全て終了（ａ点）後、ｃ点より前プリントの二次転写に入るが、この二次転写のための転写ローラ１４の転写ベルト１０に対する接触動作とクリーニングブレード１６Ａの中間転写ベルト１０への接触動作とは、略同時に前プリントの第４版（黒）トナー像の一次転写終了（ａ点）後であって次プリントの第１版（イエロー）の光書き込み開始（ｂ点）以前、つまりΔｔ１の時間の間に行なわれる。
【００６８】
上記したように、カラー画像の連続プリント時に、転写ローラ１４の中間転写ベルト１０に対する接触動作と前記クリーニングブレード１６Ａの中間転写ベルト１０に対する接触動作とを同時に、最終版の一次転写終了後でかつ次のプリントの第１版の露光工程開始以前に行なうという動作は、図１に示した中間転写ベルト１０上のマーク、マーク検知センサ５０、接離手段５２、接離手段５３およびこれら接離手段５２、５３を作動させるＣＰＵ５１などの働きにより行なわれる。よって、これらの部材が発明における制御手段の例となる。
【００６９】
このような制御手段の働きにより、転写ローラ１４の中間転写ベルト１０に対する接触動作とクリーニングブレード１６Ａの中間転写ベルト１０への接触動作とを、略同時に、一次転写終了（ａ点）後でかつ、次プリントの第１版（イエロー）の光書き込み開始（ｂ点）以前、つまり、Δｔ１の時間の間に行なうことにより、中間転写ベルトおよび感光体ベルトの駆動に影響を与える時間がトータルで短く済み、かつ一次転写中および次プリントの書き込み中に、中間転写ベルト１０および感光体１の駆動に影響を与えることなく、次プリントの第１版（イエロー）の光書き込み開始を少しでも早くできるので、結果的に中間転写ベルトの周長を短くでき、連続時のプリント枚数（単位時間当たりのプリント枚数）を多くすることができる。
【００７０】
（七）例６
図５において、二次転写工程開始（ａ点〜ｃ点）後および中間転写ベルトのクリーニング工程が開始（ａ点）後、約Δｔ１の時間後に、次プリントの第１版（イエロー）の露光工程（光書き込み）が開始（ｂ点）され、この露光工程の終了（ｄ点）と略同時に前プリントの二次転写工程および中間転写ベルトのクリーニング工程が終了（ｅ点）する。本例では、次プリントの第１版（イエロー）の光書き込みが終了（ｄ点）後に、転写ローラ１４の中間転写ベルト１０からの離間動作とクリーニングブレード１６Ａの中間転写ベルト１０からの離間動作とを同時に行なう。さらにこれら、中間転写ベルト１０からの転写ローラ１４の離間動作およびクリーニングブレード１６Ａの中間転写ベルト１０からの離間動作後に、次プリントの第２版（マゼンタ）の光書き込みを開始する。
【００７１】
上記したように、カラー画像の連続プリント時に、転写ローラ１４の中間転写ベルト１０に対する離間動作とクリーニングブレード１６Ａの中間転写ベルト１０に対する離間動作とを同時に、第１版の露光工程終了後で第２版の露光工程開始以前に行なうという動作は、図１に示した中間転写ベルト１０上のマーク、マーク検知センサ５０、接離手段５２、接離手段５３およびこれら接離手段５２、５３を作動させるＣＰＵ５１などの働きにより行なわれる。よって、これらの部材が請求項８に記載した発明における制御手段の例となる。
【００７２】
このような制御手段の働きにより、転写ローラ１４の中間転写ベルト１０からの離間動作およびクリーニングブレード１６Ａの中間転写ベルト１０からの離間動作とを同時に、第１版の光書き込み終了（ｄ点）後で第２版の光書き込み開始（ｆ点）以前、つまりΔｔ２の時間の間に行なうことにより、中間転写ベルト１０および感光体の駆動に影響を与える時間がトータルで短く済み、光書き込み中に、中間転写ベルトおよび感光体ベルトの駆動に影響を与えることなく、次プリントの第２版（マゼンタ）の光書き込み開始を少しでも早くできるので、結果的に中間転写ベルトの周長を短くでき、連続時のプリント枚数（単位時間当たりのプリント枚数）を多くできる。
【００７３】
本例においては、出力可能な最大転写紙長をＡ４縦の２９７ｍｍとしたが、出力可能が最大転写紙長をＡ３縦としたカラー画像形成装置においては、Ａ４縦２９７ｍｍの代わりにＡ３縦４２０ｍｍを適用すれば、同様の装置構成およびタイミング制御を適用でき、同様の作用効果を達成できる。
また、中間転写ベルト上にＡ４横のトナー像を２面担持することも可能であり、この場合には、Ａ４縦２９７ｍｍの代わりに、Ａ４横２１０ｍｍ×２＋紙間（例えば４０ｍｍとすると）＝４６０ｍｍを適用すれば、同様の装置構成およびタイミング制御を適用できる。
【００７４】
【発明の効果】
請求項１および請求項２記載の発明については、中間転写体への各部材（転写部材およびクリーニング部材）の接触動作を、最終版の一次転写終了後でかつ次のプリントの第１版の露光工程開始以前に行なうので、一次転写中および次プリントの光書き込み中に、中間転写体および静電像担持体の駆動に影響を与えることなく画像上に横スジなどが発生するのを防止することができるとともに、
中間転写体からの上記各部材の離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に行なうので、光書き込み中に中間転写体および潜像担持体の駆動に影響を与えることなく画像上に横スジなどが発生するのを防止することができる。
請求項３および請求項４記載の発明については、中間転写体への上記各部材の接触動作を、最終版の一次転写終了後でかつ次のプリントの第１版の露光工程開始以前に同時に行なうので、中間転写体および静電像担持体の駆動に影響を与える時間をトータルで短くし、一次転写中および次プリントの光書き込み中に、中間転写体および静電像担持体の駆動に影響を与えることなく、次プリントの第１版（イエロー）の光書き込み開始を少しでも早くし、結果的に中間転写体の周長を短くでき、連続時のプリント枚数（単位時間当たりのプリント枚数）を多くできるとともに、
中間転写体からの上記各部材の離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に同時に行なうので、中間転写体および静電像担持体の駆動に影響を与える時間をトータルで短くし、光書き込み中に、中間転写体および静電像担持体の駆動に影響を与えることなく、次プリントの第２版（マゼンタ）の光書き込み開始を少しでも早くし、結果的に中間転写体の周長を短くでき、連続時のプリント枚数（単位時間当たりのプリント枚数）を多くできる。
【図面の簡単な説明】
【図１】本発明の実施に適するカラー画像形成装置の一例としてのカラープリンタの全体構成を説明した図である。
【図２】現像装置と中間転写ベルトとの関係を部分的に拡大して説明した要部断面図である。
【図３】光書き込みと第１版（イエロー）現像を行なっているときの現像装置を説明した図である。
【図４】第４版（黒）現像を行なっているときの現像装置を説明した図である。
【図５】カラープリント時における工程および諸部材の動作タイミングを説明したタイミングチャートである。
【図６】制御手段による制御手順を説明したタイミングチャートである。
【符号の説明】
１０ （中間転写体としての）中間転写ベルト
１４ （転写部材としての）転写ローラ
１６Ａ （クリーニング部材としての）クリーニングブレード
５０ （制御手段としての）マーク検知センサ
５１ （制御手段としての）ＣＰＵ
５２ （制御手段としての）接離手段
５３ （制御手段としての）接離手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color image forming apparatus and a color image forming method in which a color superposed toner image is obtained on an intermediate transfer member and the superposed toner image is collectively transferred onto a transfer sheet.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a color image forming apparatus that enables multicolor reproduction by applying electrophotography, a color separation light image is exposed on a latent image carrier, and each formed latent image is a complementary color of the color separation light. A plurality of toner images obtained by developing with toner are superimposed on the same intermediate transfer body to perform primary transfer to form a color image, and the color image is secondarily transferred to transfer paper by electrostatic transfer to obtain a color image. Color image forming apparatuses such as full-color copying machines that obtain images are known.
[0003]
On the other hand, as a transfer member for electrostatic transfer of a toner image from a photosensitive member as an electrostatic latent image carrier to a transfer paper in a monochrome copying machine or a monochrome printer, a transfer roller system having excellent transfer paper transportability is known. ing. Therefore, also in the above-described full-color copying machine, a transfer roller can be used to electrostatically transfer the toner image on the intermediate transfer member onto the transfer paper. The transfer roller as the secondary transfer means is referred to as a transfer member.
[0004]
As an example of a color image forming apparatus using such a transfer roller in the color image forming apparatus, an electrostatic image carrier and a plurality of developments for developing a latent image formed on the electrostatic image carrier with toner. An intermediate transfer body on which the toner images of a plurality of colors formed on the electrostatic image carrier by these developing units are primarily transferred, and the superimposed toner image transferred onto the intermediate transfer body on the transfer paper. A primary transfer position on the intermediate transfer body having a transfer member that can contact and separate from the intermediate transfer member and a cleaning member that can contact and separate from the intermediate transfer member Japanese Patent Laid-Open No. 6-167842 discloses a color image forming apparatus in which the distance from the secondary transfer position to the secondary transfer position is set longer than the length of the maximum transfer paper that can be output by the color image forming apparatus.
[0005]
[Problems to be solved by the invention]
In the known technology, toner images of a plurality of colors are sequentially transferred from the photosensitive member to the intermediate transfer member on the intermediate transfer member, so that the transfer roller is prevented from being soiled during the primary transfer during the transfer. Therefore, when the transfer roller is retracted to a position separated from the intermediate transfer member and the secondary transfer is performed from the intermediate transfer member to the transfer paper, the transfer roller is interposed between the transfer papers. It is necessary to move it to a position where it contacts the transfer body.
[0006]
As described above, when the transfer roller as the transfer member is brought into contact with and separated from the intermediate transfer member, the drive of the intermediate transfer member and the drive of the photosensitive member are also affected particularly when the drive of the intermediate transfer member and the drive system are connected to the photosensitive member. When the transfer roller is brought into and out of contact with the intermediate transfer member during optical writing or primary transfer accompanying the above-mentioned contact and separation, problems such as horizontal stripes occur on the image due to load fluctuations. Also, the cleaning member is configured so as to be able to contact and separate with respect to the intermediate transfer member. Therefore, similarly to the transfer roller, it affects the driving of the intermediate transfer member and the photosensitive member, and is accompanied by the contact and separation described above. This causes a problem such as a horizontal stripe on the image due to the load fluctuation.
[0007]
  Accordingly, claims 1 to claim4According to the present invention, a color image that can avoid a member that comes in contact with and separates from the intermediate transfer member from causing a load fluctuation to the intermediate transfer member or the photosensitive member and adversely affecting image formation due to the contact and separation. It is an object to provide a forming method and a color image forming apparatus.
[0008]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention provides
(1) An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and the developer formed on the electrostatic image carrier by the developing units. The intermediate transfer body on which the toner images of a plurality of colors are primarily transferred and the intermediate transfer body for performing a secondary transfer process for transferring the superimposed toner image transferred onto the intermediate transfer body onto the transfer paper can be contacted and separated. Transfer memberAnd a cleaning member capable of contacting and separating from the intermediate transfer memberA color image forming apparatus in which the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member is set to be longer than the length of the maximum transfer paper that can be output by the color image forming apparatus. In the color image forming method performed by using the transfer member, during continuous printing of color imagesAnd the cleaning memberContact operation with the intermediate transfer member after completion of the primary transfer of the final plate and before the start of the exposure process of the first plate of the next printAnd the separation operation of the transfer member and the cleaning member from the intermediate transfer member is performed after the exposure process of the first plate and before the exposure process of the second plate.(Claim 1).
[0009]
(2) An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and the developer formed on the electrostatic image carrier by the developing units. The intermediate transfer body on which the toner images of a plurality of colors are primarily transferred and the intermediate transfer body for performing a secondary transfer process for transferring the superimposed toner image transferred onto the intermediate transfer body onto the transfer paper can be contacted and separated. Transfer memberAnd a cleaning member capable of contacting and separating from the intermediate transfer memberA color image forming apparatus in which the distance from the primary transfer position to the secondary transfer position on the intermediate transfer body is set to be longer than the length of the maximum transfer paper that can be output by the color image forming apparatus. In the continuous printing of color images, the transfer memberAnd the cleaning memberContact operation with the intermediate transfer member after completion of the primary transfer of the final plate and before the start of the exposure process of the first plate of the next printAnd the separation operation of the transfer member and the cleaning member from the intermediate transfer member is performed after the exposure process of the first plate and before the exposure process of the second plate.It has control means to perform (claim 2).
[0010]
(3) An electrostatic image carrier, a plurality of developing units that develop the latent image formed on the electrostatic image carrier with toner, and the developer formed on the electrostatic image carrier by these developing units. The intermediate transfer body on which the toner images of a plurality of colors are primarily transferred and the intermediate transfer body for performing a secondary transfer process for transferring the superimposed toner image transferred onto the intermediate transfer body onto the transfer paper can be contacted and separated. Transfer memberAnd a cleaning member capable of contacting and separating from the intermediate transfer memberA color image forming apparatus in which the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member is set to be longer than the length of the maximum transfer paper that can be output by the color image forming apparatus. In the color image forming method to be used, during continuous printing of color images,Performing the contact operation of the transfer member and the cleaning member with the intermediate transfer body simultaneously after the completion of the primary transfer of the final plate and before the start of the exposure process of the first plate of the next print; andThe transfer memberAnd the cleaning memberIs moved away from the intermediate transfer member after the first plate exposure process and before the second plate exposure process starts.at the same time(Claim 3).
[0011]
(4) An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and the developer formed on the electrostatic image carrier by these developing units. The intermediate transfer body on which the toner images of a plurality of colors are primarily transferred and the intermediate transfer body for performing a secondary transfer process for transferring the superimposed toner image transferred onto the intermediate transfer body onto the transfer paper can be contacted and separated. Transfer memberAnd a cleaning member capable of contacting and separating from the intermediate transfer memberA color image forming apparatus in which the distance from the primary transfer position to the secondary transfer position on the intermediate transfer body is set to be longer than the length of the maximum transfer paper that can be output by the color image forming apparatus. During continuous printing of color images,Performing the contact operation of the transfer member and the cleaning member with the intermediate transfer body simultaneously after the completion of the primary transfer of the final plate and before the start of the exposure process of the first plate of the next print; andThe transfer memberAnd the cleaning memberIs moved away from the intermediate transfer member after the first plate exposure process and before the second plate exposure process starts.at the same timeIt has control means to perform (claim 4).
[0012]
In addition, it can comprise as follows.
(A)  An electrostatic image carrier, a plurality of developing units for developing a latent image formed on the electrostatic image carrier with toner, and a plurality of colors formed on the electrostatic image carrier by these developing units The intermediate transfer member to which the toner image is primarily transferred, and the transfer that can be brought into contact with and separated from the intermediate transfer member for performing a secondary transfer step of transferring the superimposed toner image transferred onto the intermediate transfer member onto the transfer paper. A member and a cleaning member capable of contacting and separating from the intermediate transfer member, and a distance from a primary transfer position to a secondary transfer position on the intermediate transfer member that can be output by the color image forming apparatus. In a color image forming method performed using a color image forming apparatus set to be longer than the length of a transfer paper, the contact operation of the cleaning member with the intermediate transfer member during continuous printing of a color image is performed after completion of primary transfer of the final plate. And row in the exposure step prior to the start of the first edition of the next printColor image forming method.
[0013]
(b) An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and a plurality of units formed on the electrostatic image carrier by these developing units An intermediate transfer member to which a color toner image is primarily transferred and a secondary transfer step for transferring the superimposed toner image transferred onto the intermediate transfer member onto a transfer sheet can be brought into contact with and separated from the intermediate transfer member. A transfer member and a cleaning member that can contact and separate from the intermediate transfer member, and the color image forming apparatus can output the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member. In a color image forming apparatus set to be longer than the length of the maximum transfer paper, the contact operation of the cleaning member with the intermediate transfer member during continuous printing of color images is performed after completion of primary transfer of the final plate and for the next print. First edition Having a control means for causing the exposure process starts earlierColor image forming apparatus.
[0014]
(c) An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and a plurality of units formed on the electrostatic image carrier by these developing units An intermediate transfer member to which a color toner image is primarily transferred and a secondary transfer step for transferring the superimposed toner image transferred onto the intermediate transfer member onto a transfer sheet can be brought into contact with and separated from the intermediate transfer member. A transfer member and a cleaning member that can contact and separate from the intermediate transfer member, and the color image forming apparatus can output the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member. In a color image forming method performed using a color image forming apparatus set to be longer than the length of the maximum transfer paper, the separation operation of the cleaning member with respect to the intermediate transfer member is performed during the continuous printing of color images. End Performed later in the second edition of the exposure process starts earlierColor image forming method.
[0015]
(d) An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and a plurality of units formed on the electrostatic image carrier by these developing units An intermediate transfer member to which a color toner image is primarily transferred and a secondary transfer step for transferring the superimposed toner image transferred onto the intermediate transfer member onto a transfer sheet can be brought into contact with and separated from the intermediate transfer member. A transfer member and a cleaning member that can contact and separate from the intermediate transfer member, and the color image forming apparatus can output the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member. In the color image forming apparatus set to be longer than the maximum transfer paper length, the separation operation of the cleaning member with respect to the intermediate transfer member during continuous printing of the color image is performed after the exposure process of the first plate is completed. Before starting the process Having a control means for NawaColor image forming apparatus.
[0016]
(e) An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and a plurality of units formed on the electrostatic image carrier by these developing units An intermediate transfer member to which a color toner image is primarily transferred and a secondary transfer step for transferring the superimposed toner image transferred onto the intermediate transfer member onto a transfer sheet can be brought into contact with and separated from the intermediate transfer member. A transfer member and a cleaning member that can contact and separate from the intermediate transfer member, and the color image forming apparatus can output the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member. In a color image forming method performed using a color image forming apparatus set to be longer than the length of the maximum transfer paper, during the continuous printing of a color image, the contact operation of the transfer member with the intermediate transfer member and the middle of the cleaning member Performing a contact operation to the transfer member at the same time, after the primary transfer completion of final and the exposure process starts earlier first edition of the next printColor image forming method.
[0017]
(f) An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and a plurality of units formed on the electrostatic image carrier by these developing units An intermediate transfer member to which a color toner image is primarily transferred and a secondary transfer step for transferring the superimposed toner image transferred onto the intermediate transfer member onto a transfer sheet can be brought into contact with and separated from the intermediate transfer member. A transfer member and a cleaning member that can contact and separate from the intermediate transfer member, and the color image forming apparatus can output the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member. In a color image forming apparatus set to be longer than the maximum transfer paper length, the contact operation of the transfer member with the intermediate transfer member and the contact operation of the cleaning member with the intermediate transfer member are simultaneously performed during continuous printing of color images. And after the primary transfer completion of the final version has the first edition control means for causing the exposure step prior to the start of the next printingColor image forming apparatus.
[0018]
(g) An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and a plurality of units formed on the electrostatic image carrier by these developing units An intermediate transfer member to which a color toner image is primarily transferred and a secondary transfer step for transferring the superimposed toner image transferred onto the intermediate transfer member onto a transfer sheet can be brought into contact with and separated from the intermediate transfer member. A transfer member and a cleaning member that can contact and separate from the intermediate transfer member, and the color image forming apparatus can output the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member. In a color image forming method performed using a color image forming apparatus set to be longer than the length of the maximum transfer paper, during the continuous printing of a color image, the separating operation of the transfer member from the intermediate transfer member and the middle of the cleaning member And separating operation with respect to the transfer member at the same time, exposure Engineering first version
After the process is completed and before the exposure process of the second editionColor image forming method.
[0019]
(H) an electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and the developer formed on the electrostatic image carrier by the developing units. An intermediate transfer member to which toner images of a plurality of colors are primarily transferred, and the intermediate transfer member for performing a secondary transfer step of transferring the superimposed toner image transferred onto the intermediate transfer member onto a transfer sheet. A transfer member capable of being moved toward and away from the intermediate transfer member, and the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member can be output by the color image forming apparatus. In the color image forming apparatus set to be longer than the length of the maximum transfer paper, the separation operation of the transfer member with respect to the intermediate transfer member and the separation operation of the cleaning member with respect to the intermediate transfer member are performed during continuous printing of color images. Sometimes, the control means to perform the exposure process starts earlier second edition after end of the first edition of the exposure stepA color image forming apparatus having the same.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
(1) Examples common to the inventions described in each claim
In FIG. 1 showing a full-color printer as an example of an image forming apparatus suitable for carrying out the present invention, a belt-like photosensitive member 1 as a latent image carrier is uniformly charged by a charging charger 4 and then a laser optical device 5. Thus, scanning exposure is performed based on the image information, and an electrostatic latent image is formed on the surface. Here, the image information to be exposed is single-color image information obtained by decomposing a desired full-color image into yellow, magenta, cyan, and black color information. The formed electrostatic latent image includes a rotary color developing device 6 having three developing units containing yellow, magenta, and cyan color toners, and a black color image provided separately from the color developing device 6. A developing device 7 having a black developing device containing toner is overlaid with predetermined yellow, magenta, cyan, and black toners to form superimposed toner images of a plurality of colors on the photoreceptor 1.
[0021]
The color developing device 6 and the developing device 7 are each provided with a developing roller that comes close to or in contact with the photoreceptor 1 at a predetermined position, and develops the latent image on the photoreceptor 1 in a non-contact or contact state. It has a function. Reference numeral 10 denotes an intermediate transfer belt as an intermediate transfer member. The intermediate transfer belt 10 is installed between rotating rollers 11 and 12 and is rotated by driving of the rotating rollers 11 and 12.
[0022]
The photoreceptor 1 is installed between the rotation rollers 2 and 3 and is rotated in the direction of arrow A in the figure by driving the rotation rollers. The rotation roller 11 or the rotation roller 12 and the rotation roller 2 or the rotation roller 3 are connected by appropriate connection means such as a gear and a pulley so as to be driven by a common drive motor. In the primary transfer position E where the intermediate transfer belt 10 is in contact with each other, it is rotated in the same direction synchronously so that the relative speed becomes zero.
[0023]
The photosensitive member 1 is uniformly charged by the charging charger 4. Next, an intermediate transfer that rotates in the direction of arrow B in the drawing in synchronization with the photosensitive member 1 every time it is exposed to light of each color from the laser optical device 5 and developed by a developing device 6 or a developing device 7 described later. By transferring an appropriate transfer bias voltage to the primary transfer bias brush 13 provided on the inner side of the intermediate transfer belt 10 for each of monochrome colors of yellow, magenta, cyan and black on the belt 10, the images are sequentially transferred. , It is overprinted.
[0024]
That is, on the intermediate transfer belt 10, a magenta toner image as a second plate on a yellow toner image as a first plate, a cyan toner image as a third plate thereon, and a fourth plate thereon. The black toner images are superimposed to form a color toner image.
[0025]
  Intermediate transfer belt10The superposed toner images of yellow, magenta, cyan and black toners superimposed on the top are collectively transferred by the transfer roller 14 onto the transfer paper conveyed from the paper feed cassette 8 to the transfer section via the paper feed roller 9 and the registration roller 60. Is done. After the transfer is completed, the transfer paper is fixed by the fixing device 18 to complete a full color image.
[0026]
Reference numeral 15 denotes a waste toner collecting container including the cleaning blade 15A of the photoreceptor 1, and reference numeral 16 denotes a cleaning device for the intermediate transfer belt 10. The cleaning blade 16A of the cleaning device 16 is used for the intermediate transfer belt 10 during image formation. It is kept at a position separated from the surface, and is pressed against the surface of the intermediate transfer belt 10 as shown in the drawing only when cleaning the toner image after paper transfer.
[0027]
FIG. 2 shows an example of a color developing device which is a part of the color image forming apparatus shown in FIG. In FIG. 2, a black developing device 7 containing a developing device using black toner is disposed in the vicinity of the photosensitive member 1, in addition to a rotating (revolver type or rotary type) developing device 6 as a color developing device. Has been. In the developing device 6, a casing 20 forming a rotating body is provided to be rotatable about a rotation center O, and the casing 20 is rotated in the direction of arrow C by a drive mechanism (not shown). The casing 20 has a shape that divides the developing device into three parts as shown by hatching, whereby a developing device 22-Y using yellow toner, a developing device 22-M using magenta toner, and cyan. A developing unit 22-C made of toner is formed.
[0028]
FIG. 3 shows a state in which the developing roller 23Y of one developing device 22-Y in the developing device 6 shown in FIG. Each of the developing units 22-Y, 22-M, and 22-C is provided with cylindrical developing rollers 23Y, 23M, and 23C as developer conveying members. Each of these developing rollers 23Y, 23M, and 23C is arranged so that a part of the developing roller 23Y, 23M, and 23C is exposed to the outside from the opening provided in the casing 20, and the developing device 6 is shown by an arrow in the drawing in synchronization with the color information. Rotate in the C direction to develop the corresponding electrostatic latent image.
[0029]
The developing devices 22-Y, 22-M, 22-C of the developing device 6 and the developing device of the developing device 7 in this example use a non-magnetic one-component developer, and as described above, yellow, magenta, cyan, black Each toner is stored, and the developing device 6 is rotated around the rotation center O so that a predetermined developing device is positioned at a predetermined developing position, and the photosensitive belt 1 is sequentially used by toner of the corresponding developing device. The electrostatic latent image formed thereon is developed, and the toner images are superimposed on the intermediate transfer belt 10 and transferred onto the transfer paper as described above, thereby forming a full color image.
[0030]
  FIG. 4 shows a state in which the developing roller 23 of the developing device 7 is at a predetermined developing position on the photoreceptor 1. The developing device 7 is composed of a developing device of a type containing black toner in a developing container 41, and is integrally formed as a so-called developing cartridge in which the end of the toner is the life of the developing device and the replacement time. In the developing device 7 as well as the developing rollers 23Y, 23M, and 23C of the developing devices 22-Y, 22-M, and 22-C of the developing device 6, the developing roller 23 and the photosensitive member 1 have a predetermined linear velocity ratio. Are arranged in opposition to the photosensitive member 1 so as to move in the same direction as the movement direction of the photosensitive member 1 indicated by an arrow A, that is, to rotate together. Above the developing roller 23, a supply roller 31 made of an elastic material such as polyurethane foam is slid in the sliding direction in the same direction as the developing roller 23 with a predetermined linear velocity ratio and rotates together with the developing roller 23. Yes. Further, a thin layer blade 32 made of an elastic material such as a stainless steel plate having a thickness of about 0.1 mm or urethane rubber is provided so that one end thereof is in contact with the developing roller 23. In the developing container 41, a paddle 42 having a plurality of blade-like portions for stirring the toner in the vicinity of the thin layer blade 32 is provided. Further, the supply roller 31 and the developing roller23A first agitator 43 and a second agitator 44 for conveying and stirring the toner are provided on the side.
[0031]
The developing device 7 is guided and supported in a movable state in directions indicated by arrows D and D ′ that are in contact with and away from the photoreceptor 1 by a pressing unit (not shown), and the direction of the arrow D ′ that is in a direction away from the photoreceptor 1. The developing roller 23 and the photosensitive member 1 are brought into contact with and separated from each other by the rotation of the cam 45.
[0032]
  FigureIn the full-color printer shown in FIG. 1, each means for controlling the contact and separation of the transfer roller 14 with respect to the intermediate transfer belt 10 and for controlling the contact and separation of the cleaning blade 16A with respect to the intermediate transfer belt 10 will be described.YouThe
  In FIG. 1, a mark detection sensor 50 is provided so as to face an arbitrary portion outside the image forming area on the outer peripheral surface of the intermediate transfer belt 10. Further, a mark that can be read by the mark detection sensor 50 is marked on the intermediate transfer belt 10 that moves in a region that can be detected by the mark detection sensor 50. A mark reading signal from the mark detection sensor 50 is input to a CPU (central processing unit) 51. An output signal is output from the CPU 51 to the contact / separation means 52 and the contact / separation means 53, respectively.
[0033]
  The contact / separation means 52 includes, for example, a solenoid coupled to a casing or the like that houses the transfer roller 14.AndAre connected by a link or the like. For convenience, this connecting means is shown by a double line in FIG. The casing is slidably supported in a direction in which the transfer roller 14 contacts and separates from the intermediate transfer belt 10, and is in contact with the casing by being urged by an elastic means in the contact direction. When an ON signal is input to the solenoid, the casing is pulled and moved by the solenoid, and the transfer roller 14 is separated from the intermediate transfer belt 10. When an off signal is input to the solenoid, the transfer roller 14 comes into contact with the intermediate transfer belt 10.
[0034]
The same configuration as the relationship between the contact / separation means 52 and the transfer roller 14 is also applied to the contact / separation means 53 and the cleaning blade 16A. As a result, when the CPU 51 outputs an ON signal to the solenoid constituting the contact / separation means 53, the cleaning blade 16A is separated from the intermediate transfer belt 10, and when an OFF signal is output, the cleaning blade 16A is applied to the intermediate transfer belt 10. It comes into contact.
[0035]
  In the above explanation,LesA transfer roller for the intermediate transfer belt 10 is moved by moving a casing containing the transfer roller 14 or a casing containing the cleaning blade 16A by using a half-rotation clutch or a rotary solenoid instead of the noid. 14, and contact / separation control of the cleaning blade 16 </ b> A with respect to the intermediate transfer belt 10 can also be performed.
[0036]
An example of the contents of control in the CPU 51 is shown in FIG. In FIG. 6, when a print start command is issued in step S1, the printer shown in FIG. 1 starts driving according to a predetermined sequence, and the image forming process proceeds. In step S2, it is determined whether or not a mark is detected. When the mark is detected by the rotation of the intermediate transfer belt 10, this detection signal is taken into the CPU 51, and in step S3, it is determined whether or not the continuous print mode is set. If the print mode is not the continuous print mode, the process proceeds to step S4, and a single print is executed on the basis of the mark detection time.
[0037]
If it is determined in step S3 that the print mode is the continuous print mode, the process proceeds to step S5, and a continuous print sequence is executed with the mark detection time as a reference. The specific contents of this continuous print scene sequence are as described in accordance with FIG. In step S5, every time one print is completed, the process of going through step S6 to step S2 is repeated until the commanded number of prints is completed.
[0038]
In FIG. 1, the photosensitive member 1 is in contact with the position of the outer peripheral surface of the intermediate transfer belt 10 corresponding to the portion where the primary transfer bias brush 13 is provided, and primary transfer is performed at the primary transfer position E which is this portion. . The distance from the primary transfer position E to the secondary transfer position F where the transfer roller 14 is in contact with the intermediate transfer belt 10 in the direction indicated by the arrow B in which the intermediate transfer belt moves from the primary transfer position E is based on the transfer paper that can be output. Among them, the intermediate transfer belt 10 is set so that the length in the feeding direction is the maximum, but the length in the feeding direction of the maximum transfer paper (hereinafter referred to as the maximum transfer paper length) is not less than Around the intermediate transfer belt 10, a photosensitive member 1, a primary transfer bias brush 13, and a transfer roller 14 are arranged.
[0039]
Specifically, when the maximum transfer paper length that can be output is 297 mm in the A4 length (when the longitudinal direction of the paper is the feed direction), the intermediate transfer belt from the primary transfer position E to the secondary transfer position F is used. The distance along the outer peripheral surface of 10 is set to 301.1 mm.
[0040]
By arranging and setting in this manner, the toner image is transferred when the fourth version (black toner image) of the A4 vertical size toner image is completely transferred from the photosensitive belt to the intermediate transfer belt at the primary transfer position E. This means that the tip of the head has not yet reached the secondary transfer position. Accordingly, after all the fourth version (black toner image) of the A4 vertical size toner image is transferred from the photosensitive belt to the intermediate transfer belt, the transfer roller 14 is moved from the position where the intermediate transfer belt 10 is retracted to the intermediate transfer belt. The transfer paper is moved to a position where it contacts the belt 10, and secondary transfer can be performed under this state.
[0041]
By arranging and operating in this way, the contact operation of the transfer roller 14 with respect to the intermediate transfer belt 10 can be performed after the completion of the primary transfer, and the transfer roller 14 may come into contact with the transfer belt 10 to cause load fluctuation. However, since it does not affect the driving of the intermediate transfer belt 10 and the photosensitive member 1 during the primary transfer, it is possible to avoid the occurrence of horizontal stripes on the image.
[0042]
(two)Example 1
  This will be described with reference to FIGS. 1 to 5 as appropriate.
  In forming a color image, first, the photosensitive member 1 is driven, and at the same time, charging is performed by the charging charger 4. Next, an exposure process (optical writing) is performed with light from the laser optical device 5, and an electrostatic latent image for the first plate yellow is formed on the photoreceptor 1. When this electrostatic latent image moves to the developing position of the developing position 6, color development with yellow toner is performed by the developing device 22-Y. This yellow toner image is transferred onto the intermediate transfer belt 10 at the primary transfer position E by bias application by the primary transfer bias brush 13.
[0043]
After developing with the yellow toner, the developing device 6 is rotated by the rotation driving mechanism, and the developing device 22 -M using magenta toner faces the developing position on the photosensitive member 1. On the other hand, an electrostatic latent image for the second plate magenta is formed on the photosensitive member 1 so as to synchronize with the yellow toner image on the intermediate transfer belt 10, and this magenta electrostatic latent image is moved to the developing position. In synchronism with this, the developing unit 22-M performs color development with magenta. Then, the magenta toner image is superimposed and transferred onto the intermediate transfer belt 10 at the primary transfer position E by applying the bias of the primary transfer bias brush 13 in the same manner as the yellow toner image. The steps so far are omitted in FIG. In FIG. 5, the subsequent color development and primary transfer steps are similarly performed during the time indicated by the solid line. After the color development of the third plate (cyan), the developing device 6 is rotated by a rotation driving mechanism, and any of the developing devices 22 -Y, 22 -M, and 22 -C does not face the photosensitive member 1. For example, it stops at the position shown in FIGS.
[0044]
Finally, the fourth (black) electrostatic latent image is synchronized with the first (yellow), second (magenta), and third (cyan) superimposed toner images on the intermediate transfer belt 10. In synchronization with the formation of the electrostatic latent image that has been formed and moved to the developing position where the developing device 7 is disposed, the developing device 7 is moved to the developing position on the photosensitive member 1 by the rotation of the cam 45, and black. Development is performed. The black toner image resulting from this black development is also transferred onto the superimposed toner image on the intermediate transfer belt 10 in the same manner.
[0045]
After all the primary transfer of the black toner image is completed, the transfer roller 14 is sandwiched from the position where the transfer roller 14 is separated and retracted from the intermediate transfer belt 10 to the secondary transfer position F where the intermediate transfer belt 10 contacts the intermediate transfer belt 10 during the time Δt1. The secondary transfer onto the transfer paper is performed.
The timing chart shown in FIG. 5 is for continuous printing. After all primary transfer of the toner image of the fourth printing (black) of the previous printing is completed (point a), the light of the first printing (yellow) of the next printing. Writing is started (point b).
[0046]
As described above, during continuous printing of color images, the contact operation of the transfer roller 14 with respect to the intermediate transfer belt 10 is performed after the completion of the primary transfer of the final plate and before the start of the exposure process of the first plate of the next print. 1 is performed by the functions of the mark on the intermediate transfer belt 10 shown in FIG. 1, the mark detection sensor 50, the contact / separation means 52, and the CPU 51 that operates the contact / separation means. Therefore, these members are examples of the control means in the invention described in claim 2. Here, it is sufficient for the CPU 51 to have a function of controlling the contact / separation means 52, and it is not always necessary to have a function of controlling the contact / separation means 53.
[0047]
Due to the function of such a control means, as described in FIG. 5, the contact operation of the transfer roller 14 with respect to the intermediate transfer belt 10 is after the primary transfer of the final plate (fourth plate) of the previous print and the next. This is performed before the start of optical writing (point b) of the first print (yellow). As described above, the contact operation of the transfer roller 14 included in the secondary transfer process is performed after the end of primary transfer (point a) and before the start of optical writing (point b) of the first print (yellow) of the next print, that is, Δt1. By performing at the point c within the time, horizontal streaks or the like are generated on the image without affecting the driving of the intermediate transfer belt and the photosensitive belt during primary transfer and optical writing of the next print. Can be prevented.
[0048]
The start of the secondary transfer process is as follows: (1) Transfer paper leading edge to the secondary transfer position, (2) Contact of the transfer roller to the intermediate transfer belt at the secondary transfer position, (3) To the secondary transfer position The intermediate transfer belt is composed of three operations: the front end of the toner image carried on the intermediate transfer belt. The ideal timing of these three operations is that the above three operations (1), (2), and (3) are performed simultaneously. However, the same timing must be in the order of at least (1) → (2) → (3) because there is a factor that cannot be precisely controlled, such as the occurrence of minute slips due to the type of transfer paper. It is. The time required for these series of operations is about 0.04 sec in consideration of the time from (1) to (3) in consideration of the allowable whiteout width of 4.2 mm at the leading edge of the transfer paper. At this time, the timing of (1) or (3) or the operation of (2) may be any timing as long as it is between (1) and (3).
[0049]
In the image forming apparatus of this example, the maximum usable transfer paper size is A4 size, and the maximum transfer paper length in the transfer paper transport direction is 297 mm in A4 vertical feed. When the maximum usable transfer paper size is A4 vertical feed, Δt1 = 0.18 sec. At this time, the time from point a to point c is 0.02 sec.
Also, the maximum usable transfer paper size is a double letter horizontal two-sheet take (US letter size 216 mm × 2 + paper interval 40 mm = 472 mm). In this size, Δt1 = 0.21 sec, from point a to point c Is 0.03 sec.
Furthermore, if the maximum usable transfer paper size is A3, the time Δt1 naturally increases, Δt1 = 0.75 sec, and the time from point a to point c is 0.57 sec.
[0050]
(three)Example 2
  In FIG. 5, after the secondary transfer process is started (point c), optical writing of the first print (yellow) of the next print is started (point b), which is substantially the end of the optical writing process (point d). At the same time, the secondary transfer process of the previous print ends (point e). In this example, the transfer roller 14 is separated from the intermediate transfer belt 10 after the optical writing process of the first print (yellow) of the next print is completed (point d). Then, after the separation operation of the transfer roller 14 from the intermediate transfer belt 10, optical writing of the second print (magenta) of the next print is started (point f).
[0051]
  As described above, during the continuous printing of color images, the operation of causing the transfer roller 14 to move away from the intermediate transfer belt 10 is performed after the exposure process of the first plate and before the exposure process of the second plate. The operation is performed by the marks on the intermediate transfer belt 10 shown in FIG. 1, the mark detection sensor 50, the contact / separation means 52, and the CPU 51 that operates the contact / separation means. Therefore, these membersDepartThis is an example of the control means in Ming. Here, it is sufficient for the CPU 51 to have a function of controlling the contact / separation means 52, and it is not always necessary to have a function of controlling the contact / separation means 53.
[0052]
As described with reference to FIG. 5, the operation of the control means causes the transfer roller 14 to move away from the intermediate transfer belt 10 after the first plate exposure process (after completion of optical writing) (point d). When the transfer roller 14 is separated from the intermediate transfer belt 10 by starting before the exposure process of two plates (start of optical writing) (point f), that is, during the time Δt2 shown in FIG. Even if there is a load fluctuation, optical writing is not in progress, so that it is possible to avoid occurrence of a horizontal stripe or the like on the image due to a load fluctuation of the intermediate transfer belt 10 and the photoreceptor 1.
[0053]
(Four)Example 3
  In FIG. 5, first, the photosensitive member 1 is driven, and at the same time, charging is performed by the charging charger 4. Next, optical writing is performed in the exposure process, and a yellow electrostatic latent image is formed on the photoreceptor 1.
  When the electrostatic latent image moves to the development position, development is performed by the yellow developer 22-Y. The toner image is primarily transferred onto the intermediate transfer belt 10 at the primary transfer position E by bias application by the primary transfer bias brush 13. Next, the developing device 6 is rotated by the rotation driving device so that the magenta developing device 22 -M faces a predetermined developing position on the photosensitive member 1. Further, a magenta electrostatic latent image is formed on the photosensitive member 1 so as to be synchronized with the toner image on the intermediate transfer belt 10, and the developing device 22 is synchronized with the movement of the electrostatic latent image to the developing position. Development is performed by -M. The magenta toner image is superimposed and transferred onto the intermediate transfer belt by bias application by the primary transfer bias brush 13. The steps so far are omitted in FIG. In FIG. 5, optical writing of the third version (cyan) image is performed next.
Similarly, the color development and primary transfer processes are similarly performed during the time indicated by the solid line. After the development of the third plate (cyan), the developing device 6 is rotated by a rotation driving mechanism, and any of the developing devices 22Y, 22M, and 22C is not opposed to the photosensitive member 1, for example, FIGS. 4 is stopped at the position shown in FIG.
[0054]
Finally, the fourth (black) electrostatic latent image is synchronized with the first (yellow), second (magenta), and third (cyan) superimposed toner images on the intermediate transfer belt 10. In synchronism with the movement of the developing device 7 to the developing position, the developing device 7 is moved to the developing position on the photosensitive member 1 by the rotation of the cam 45, and black development is performed. The black toner image resulting from this black development is similarly transferred onto the superimposed toner image on the intermediate transfer belt.
[0055]
After all the primary transfer of the black toner image is completed, the transfer roller 14 moves from the position where the transfer roller 14 is separated from the intermediate transfer belt 10 to the secondary transfer position F where the intermediate transfer belt contacts with the intermediate transfer belt 10 during the time Δt1. Secondary transfer onto transfer paper is performed.
[0056]
Further, after all the primary transfer of the black toner image is completed, the cleaning blade 16A, which is a cleaning member of the intermediate transfer belt 10, moves from a position retracted from the intermediate transfer belt 10 to a position in contact with the intermediate transfer belt 10, and the intermediate transfer belt 10 The remaining toner on the top is cleaned.
[0057]
The timing chart shown in FIG. 5 shows a state at the time of continuous printing. After all primary transfer of the fourth printing (black) toner image of the previous printing is completed (point a), the first printing of the next printing (yellow). Is started (point b). In this example, the contact operation of the cleaning blade 16A with respect to the intermediate transfer belt 10 is after the completion of the primary transfer (point a) of the fourth plate (black) and the start of optical writing of the first plate (yellow) of the next print. (Point b) Before, that is, within the time Δt1 in FIG.
[0058]
  As described above, during continuous printing of color images, the contact operation of the cleaning blade 16A with the intermediate transfer belt 10 is performed after completion of the primary transfer of the final plate and before the start of the exposure process of the first plate of the next print. 1 is performed by the functions of the mark on the intermediate transfer belt 10 shown in FIG. 1, the mark detection sensor 50, the contact / separation means 52, and the CPU 51 that operates the contact / separation means. Therefore, these membersDepartThis is an example of the control means in Ming. Here, it is sufficient that the CPU 51 has a function of controlling the contact / separation means 53, and it is not always necessary to have a function of controlling the contact / separation means 52.
[0059]
As described with reference to FIG. 5, the operation of the control means causes the contact operation of the cleaning blade 16A to the intermediate transfer belt 10 after the completion of the primary transfer (point a) and for the first print (yellow) of the next print. By performing before the start of optical writing (point b), even if the load of the intermediate transfer belt 10 and the photosensitive member 1 changes due to the cleaning blade 16A coming into contact with the intermediate transfer belt 10, the light of the primary transfer and the next print Since writing is not being performed, problems such as horizontal stripes do not occur on the image even if there are load fluctuations of the intermediate transfer belt and the photosensitive belt.
[0060]
(5)Example 4
  In FIG. 5, after the cleaning process of the intermediate transfer belt 10 is started by the cleaning blade 16A coming into contact with the intermediate transfer belt 10, optical writing of the first plate (yellow) of the next print is started (point b). The intermediate transfer belt 10 is substantially simultaneously with the end of the optical writing process (point d).FromThe cleaning process of the intermediate transfer belt is completed when the cleaning blade 16A is separated. In this example, the cleaning blade 16A is separated from the intermediate transfer belt 10 after the optical writing of the first plate (yellow) of the next print is completed (point d). Furthermore, after the cleaning blade 16A is moved away from the intermediate transfer belt 10, optical writing of the second print (magenta) of the next print is started (point f).
[0061]
  As described above, during the continuous printing of color images, the operation of separating the cleaning blade 16A from the intermediate transfer belt 10 after the completion of the exposure process of the first plate and before the start of the exposure process of the second plate is shown in FIG. The marks on the intermediate transfer belt 10, the mark detection sensor 50, the contact / separation means 52, and the CPU 51 for operating the contact / separation means shown in FIG. Therefore, these membersDepartThis is an example of the control means in Ming. Here, it is sufficient that the CPU 51 has a function of controlling the contact / separation means 53, and it is not always necessary to have a function of controlling the contact / separation means 52.
[0062]
By such a function of the control means, the operation of separating the cleaning member of the intermediate transfer belt is performed after the exposure process (optical writing) of the first plate (yellow) of the next print (point d) and the light of the second plate (magenta). By performing this operation before the start of writing (point f), that is, during time Δt2, even when the load of the intermediate transfer belt 10 and the photosensitive member 1 changes due to the cleaning blade 16A being separated from the intermediate transfer belt 10, optical writing is in progress. Therefore, even if there are fluctuations in the load on the intermediate transfer belt and the photoconductor, problems such as horizontal stripes do not occur on the image.
[0063]
(Six)Example 5
  In FIG. 5, first, the photosensitive member 1 is driven, and at the same time, charging is performed by the charging charger 4. Next, optical writing is performed in the exposure process, and a yellow electrostatic latent image is formed on the photoreceptor 1.
  When the electrostatic latent image moves to the development position, development is performed by the yellow developer 22-Y. The toner image is primarily transferred onto the intermediate transfer belt 10 at the primary transfer position E by bias application by the primary transfer bias brush 13. Next, the developing device 6 is rotated by the rotation driving device so that the magenta developing device 22 -M faces the developing position on the photosensitive member 1. Further, a magenta electrostatic latent image is formed on the photosensitive member 1 so as to be synchronized with the toner image on the intermediate transfer belt 10, and the developing device 22 is synchronized with the movement of the electrostatic latent image to the developing position. Development is performed by -M. The magenta toner image is superimposed and transferred onto the intermediate transfer belt by bias application by the primary transfer bias brush 13. The steps so far are omitted in FIG.
[0064]
In FIG. 5, the subsequent steps of the third version (cyan) image optical writing, color development, and primary transfer are similarly performed during the time indicated by the solid line. After the development of the third plate (cyan), the developing device 6 is rotated by a rotation driving mechanism, and any of the developing devices 22Y, 22M, and 22C is not opposed to the photosensitive member 1, for example, FIGS. It stops at the position shown in FIG.
[0065]
Finally, the fourth (black) electrostatic latent image is synchronized with the first (yellow), second (magenta), and third (cyan) superimposed toner images on the intermediate transfer belt 10. In synchronism with the movement of the developing device 7 to the developing position, the developing device 7 is moved to the developing position on the photosensitive member 1 by the rotation of the cam 45, and black development is performed. The black toner image resulting from this black development is similarly transferred onto the superimposed toner image on the intermediate transfer belt.
[0066]
After all the primary transfer of the black toner image is completed, the transfer roller 14 moves from the position where the transfer roller 14 is separated from the intermediate transfer belt 10 to the secondary transfer position F where the intermediate transfer belt contacts with the intermediate transfer belt 10 during the time Δt1. Secondary transfer onto transfer paper is performed. Simultaneously with the contact operation of the transfer roller 14 with respect to the intermediate transfer belt 10, the cleaning blade 16 </ b> A moves from the position retracted from the intermediate transfer belt 10 to a position where it comes into contact with the intermediate transfer belt 10. Done.
[0067]
In the continuous printing shown in FIG. 5, after all the primary transfer of the fourth plate (black) toner image of the previous print is completed (point a), the first plate (yellow) of the next print is started from point b after a time of Δt1. Optical writing is performed. As shown in FIG. 5, in the color image forming method of this example, after the primary transfer of the fourth printing (black) toner image of the previous print is completed (point a), the secondary transfer of the previous print starts from the point c. The contact operation of the transfer roller 14 for the secondary transfer to the transfer belt 10 and the contact operation of the cleaning blade 16A to the intermediate transfer belt 10 are performed at the same time for the primary transfer of the fourth printing (black) toner image of the previous print. After the end (point a) and before the start of optical writing (point b) of the first printing (yellow) of the next print, that is, during the time of Δt1.
[0068]
  As described above, during continuous printing of color images, the contact operation of the transfer roller 14 with respect to the intermediate transfer belt 10 and the contact operation of the cleaning blade 16A with respect to the intermediate transfer belt 10 are performed simultaneously after the completion of the primary transfer of the final plate and the next. 1 is performed before the start of the exposure process of the first plate of the print, the mark on the intermediate transfer belt 10 shown in FIG. 1, the mark detection sensor 50, the contact / separation means 52, the contact / separation means 53, and the contact / separation means 52. , 53 is operated by the action of the CPU 51 and the like. Therefore, these membersDepartThis is an example of the control means in Ming.
[0069]
By such an action of the control means, the contact operation of the transfer roller 14 with respect to the intermediate transfer belt 10 and the contact operation of the cleaning blade 16A with the intermediate transfer belt 10 are substantially simultaneously after the end of the primary transfer (point a) and By performing the first printing of the next print (yellow) before the start of optical writing (point b), that is, during the time of Δt1, the time that affects the driving of the intermediate transfer belt and the photosensitive belt can be shortened in total. In addition, during the primary transfer and during the writing of the next print, the first writing (yellow) of the next print can be started as soon as possible without affecting the driving of the intermediate transfer belt 10 and the photosensitive member 1. As a result, the peripheral length of the intermediate transfer belt can be shortened, and the number of continuous prints (number of prints per unit time) can be increased.
[0070]
(Seven)Example 6
  In FIG. 5, after the start of the secondary transfer process (points a to c) and after the start of the intermediate transfer belt cleaning process (point a), after the time of about Δt1, the exposure process of the first plate (yellow) of the next print (Optical writing) is started (point b), and the secondary transfer process of the previous print and the cleaning process of the intermediate transfer belt are completed (point e) almost simultaneously with the end of the exposure process (point d). In this example, after the optical writing of the first plate (yellow) of the next print is completed (point d), the separating operation of the transfer roller 14 from the intermediate transfer belt 10 and the separating operation of the cleaning blade 16A from the intermediate transfer belt 10 are performed. At the same time. Further, after the separation operation of the transfer roller 14 from the intermediate transfer belt 10 and the separation operation of the cleaning blade 16A from the intermediate transfer belt 10, optical writing of the second print (magenta) of the next print is started.
[0071]
As described above, during the continuous printing of color images, the separation operation of the transfer roller 14 with respect to the intermediate transfer belt 10 and the separation operation of the cleaning blade 16A with respect to the intermediate transfer belt 10 are performed at the same time after the exposure of the first plate is completed. The operation performed before the start of the plate exposure process operates the mark on the intermediate transfer belt 10 shown in FIG. 1, the mark detection sensor 50, the contact / separation means 52, the contact / separation means 53, and the contact / separation means 52, 53. The operation is performed by the CPU 51 and the like. Therefore, these members are examples of the control means in the invention described in claim 8.
[0072]
By such a function of the control means, the separation operation of the transfer roller 14 from the intermediate transfer belt 10 and the separation operation of the cleaning blade 16A from the intermediate transfer belt 10 are performed at the same time after the end of the first plate optical writing (d point). In this case, the time that affects the driving of the intermediate transfer belt 10 and the photosensitive member can be shortened in total by performing it before the start of optical writing of the second version (point f), that is, during the time of Δt2. Since the second printing (magenta) of the next print can be started as soon as possible without affecting the driving of the intermediate transfer belt and the photosensitive belt, the peripheral length of the intermediate transfer belt can be shortened as a result. The number of prints per hour (number of prints per unit time) can be increased.
[0073]
  In this example, the maximum transfer paper length that can be output is 297 mm in A4 length, but in a color image forming apparatus in which the maximum transfer paper length that can be output is A3 length, A3 length 420 mm is used instead of A4 length 297 mm. If applied, the same device configuration and timing control can be applied, and the same effect can be achieved.
  It is also possible to carry two A4 horizontal toner images on the intermediate transfer belt. In this case, A4 horizontal 210 mm × 2 + paper interval (for example, 40 mm) = 460 mm instead of A4 vertical 297 mm. Apply the same device configuration and timing control.Can.
[0074]
【The invention's effect】
  About invention of Claim 1 and Claim 2,Since the contact operation of each member (transfer member and cleaning member) to the intermediate transfer member is performed after completion of the primary transfer of the final plate and before the start of the exposure process of the first plate of the next print, during the primary transfer and the next print During optical writing, it is possible to prevent occurrence of horizontal stripes on the image without affecting the driving of the intermediate transfer member and the electrostatic image carrier,
The separation of the above members from the intermediate transfer member is performed after the exposure process of the first plate and before the start of the exposure step of the second plate, so that the driving of the intermediate transfer member and the latent image carrier is affected during optical writing. It is possible to prevent the occurrence of horizontal stripes on the image without giving the image.
According to the third and fourth aspects of the present invention, the contact operation of each member to the intermediate transfer member is simultaneously performed after the primary transfer of the final plate is completed and before the exposure process of the first plate of the next print is started. Therefore, the time that affects the drive of the intermediate transfer member and the electrostatic image carrier is shortened in total, and the drive of the intermediate transfer member and the electrostatic image carrier is affected during the primary transfer and optical writing of the next print. Without giving it, the first writing (yellow) of the next print can be started as soon as possible, and as a result, the circumference of the intermediate transfer body can be shortened, and the number of prints at the time of continuous printing (number of prints per unit time) can be reduced. As much as possible
  Since the separating operation of each member from the intermediate transfer member is performed simultaneously after the exposure process of the first plate and before the start of the exposure process of the second plate, it affects the driving of the intermediate transfer member and the electrostatic image carrier. The total time is shortened, and the optical writing start of the second print (magenta) of the next print is made as soon as possible without affecting the driving of the intermediate transfer member and the electrostatic image carrier during optical writing. In particular, the peripheral length of the intermediate transfer member can be shortened, and the number of continuous prints (number of prints per unit time) can be increased.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an overall configuration of a color printer as an example of a color image forming apparatus suitable for implementing the present invention.
FIG. 2 is a cross-sectional view of a principal part illustrating a partially enlarged relationship between a developing device and an intermediate transfer belt.
FIG. 3 is a diagram illustrating a developing device during optical writing and first plate (yellow) development.
FIG. 4 is a diagram illustrating a developing device during fourth plate (black) development.
FIG. 5 is a timing chart explaining processes and operation timing of various members during color printing.
FIG. 6 is a timing chart illustrating a control procedure by a control unit.
[Explanation of symbols]
10 Intermediate transfer belt (as intermediate transfer member)
14 Transfer roller (as transfer member)
16A Cleaning blade (as cleaning member)
50 Mark detection sensor (as control means)
51 CPU (as control means)
52 Contact and separation means (as control means)
53 Contact and separation means (as control means)

Claims (4)

静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置を用いて行なうカラー画像形成方法において、
カラー画像の連続プリント時に、前記転写部材および前記クリーニング部材の前記中間転写体に対する接触動作を、最終版の一次転写終了後で、かつ、次のプリントの第１版の露光工程開始以前に行ない、かつ前記転写部材および前記クリーニング部材の前記中間転写体からの離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に行なうことを特徴とするカラー画像形成方法。An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and a plurality of colors formed on the electrostatic image carrier by these developing units An intermediate transfer member on which the toner image is primarily transferred, and a transfer member which can be brought into contact with and separated from the intermediate transfer member for performing a secondary transfer step of transferring the superimposed toner image transferred onto the intermediate transfer member onto a transfer sheet And a cleaning member that can come into contact with and separate from the intermediate transfer member, and a maximum transfer that can output the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member by the color image forming apparatus. In a color image forming method performed using a color image forming apparatus set longer than the length of paper,
During continuous printing of color images, the contact operation of the transfer member and the cleaning member to the intermediate transfer member is performed after the primary transfer of the final plate and before the exposure process of the first plate of the next print , A color image forming method , wherein the separation operation of the transfer member and the cleaning member from the intermediate transfer member is performed after the exposure process of the first plate and before the exposure process of the second plate . 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置において、
カラー画像の連続プリント時に、前記転写部材および前記クリーニング部材の前記中間転写体に対する接触動作を、最終版の一次転写終了後で、かつ、次のプリントの第１版の露光工程開始以前に行ない、かつ前記転写部材および前記クリーニング部材の前記中間転写体からの離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に行なわせる制御手段を有することを特徴とするカラー画像形成装置。An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and a plurality of colors formed on the electrostatic image carrier by these developing units An intermediate transfer member on which the toner image is primarily transferred, and a transfer member which can be brought into contact with and separated from the intermediate transfer member for performing a secondary transfer step of transferring the superimposed toner image transferred onto the intermediate transfer member onto a transfer sheet And a cleaning member that can come into contact with and separate from the intermediate transfer member, and a maximum transfer that can output the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member by the color image forming apparatus. In the color image forming apparatus set longer than the paper length,
During continuous printing of color images, the contact operation of the transfer member and the cleaning member to the intermediate transfer member is performed after the primary transfer of the final plate and before the exposure process of the first plate of the next print , And a color image having control means for causing the transfer member and the cleaning member to separate from the intermediate transfer member after the exposure process of the first plate and before the start of the exposure process of the second plate. Forming equipment. 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置を用いて行なうカラー画像形成方法において、
カラー画像の連続プリント時に、前記転写部材および前記クリーニング部材の前記中間転写体に対する接触動作を、最終版の一次転写終了後で、かつ、次のプリントの第１版の露光工程開始以前に同時に行ない、かつ前記転写部材および前記クリーニング部材の前記中間転写体からの離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に同時に行なうことを特徴とするカラー画像形成方法。An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and a plurality of colors formed on the electrostatic image carrier by these developing units An intermediate transfer member on which the toner image is primarily transferred, and a transfer member which can be brought into contact with and separated from the intermediate transfer member for performing a secondary transfer step of transferring the superimposed toner image transferred onto the intermediate transfer member onto a transfer sheet And a cleaning member that can come into contact with and separate from the intermediate transfer member, and a maximum transfer that can output the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member by the color image forming apparatus. In a color image forming method performed using a color image forming apparatus set longer than the length of paper,
During continuous printing of color images, the contact operation of the transfer member and the cleaning member to the intermediate transfer member is performed simultaneously after the completion of the primary transfer of the final plate and before the start of the exposure process of the first plate of the next print. and a color image forming method characterized by performing the transfer member and the cleaning the separating operation from the intermediate transfer body member, the second edition of the exposure process starts earlier at the same time after completion of the first edition of the exposure process. 静電像担持体と、この静電像担持体上に形成された潜像をトナーにより現像する複数の現像器と、これらの現像器により前記静電像担持体上に形成された複数の色のトナー像が一次転写される中間転写体と、この中間転写体上に転写された重ねトナー像を転写紙上に転写する二次転写工程を行なうための前記中間転写体に接離可能な転写部材と、前記中間転写体に接離可能なクリーニング部材とを有し、前記中間転写体上の一次転写位置から二次転写位置までの距離を、当該カラー画像形成装置で出力可能とされる最大転写紙の長さよりも長く設定したカラー画像形成装置において、
カラー画像の連続プリント時に、前記転写部材および前記クリーニング部材の前記中間転写体に対する接触動作を、最終版の一次転写終了後で、かつ、次のプリントの第１版の 露光工程開始以前に同時に行ない、かつ前記転写部材および前記クリーニング部材の前記中間転写体からの離間動作を、第１版の露光工程終了後で第２版の露光工程開始以前に同時に行なわせる制御手段を有することを特徴とするカラー画像形成装置。An electrostatic image carrier, a plurality of developing units for developing the latent image formed on the electrostatic image carrier with toner, and a plurality of colors formed on the electrostatic image carrier by these developing units An intermediate transfer member on which the toner image is primarily transferred, and a transfer member which can be brought into contact with and separated from the intermediate transfer member for performing a secondary transfer step of transferring the superimposed toner image transferred onto the intermediate transfer member onto a transfer sheet And a cleaning member that can come into contact with and separate from the intermediate transfer member, and a maximum transfer that can output the distance from the primary transfer position to the secondary transfer position on the intermediate transfer member by the color image forming apparatus. In the color image forming apparatus set longer than the paper length,
During continuous printing of color images, the contact operation of the transfer member and the cleaning member to the intermediate transfer member is performed simultaneously after the completion of the primary transfer of the final plate and before the start of the exposure process of the first plate of the next print. And a control means for causing the transfer member and the cleaning member to move away from the intermediate transfer member simultaneously after the exposure process of the first plate and before the start of the exposure process of the second plate. Color image forming apparatus.
JP10218096A 1996-04-24 1996-04-24 Color image forming method and color image forming apparatus Expired - Fee Related JP3639037B2 (en)

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