JP4336152B2 - Transfer device and image forming apparatus - Google Patents

Transfer device and image forming apparatus Download PDF

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Publication number
JP4336152B2
JP4336152B2 JP2003181436A JP2003181436A JP4336152B2 JP 4336152 B2 JP4336152 B2 JP 4336152B2 JP 2003181436 A JP2003181436 A JP 2003181436A JP 2003181436 A JP2003181436 A JP 2003181436A JP 4336152 B2 JP4336152 B2 JP 4336152B2
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transfer belt
intermediate transfer
image
bias
transfer
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JP2005017626A (en
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宏美 荻山
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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、バイアス電圧が印加されたローラによってトナー像を被転写体に転写する転写装置及び画像形成装置に関する。
【0002】
【従来の技術】
画像信号に応じてレーザ光等により感光体上に静電潜像を形成し、その静電潜像をトナー像にして転写材等に転写する電子写真式の画像形成装置は、複写機、プリンタ、ファクシミリなどに広く普及している。また、近年はカラー画像信号によりカラー画像を転写材等に転写するカラー画像形成装置も提供されている。
【0003】
カラー画像形成の代表的方法は、複数の感光体上に形成される色の異なるトナー画像を中間転写体に重ねながら転写させ、しかる後に転写材に一括して転写させる中間転写方式と、複数の像担持体である感光体上に形成される色の異なるトナー画像を直接転写材に重ねながら転写させる直接転写方式とがある。複数の感光体を転写材または中間転写体に対向させ並べて配置することから、タンデム方式と呼ばれ、感光体毎にイエロー(Y)、マゼンタ(M)、シアン(C)、ブラック(K)の各色に対して静電潜像の形成、現像などの電子写真プロセスを実行させ、中間転写方式においては走行中の中間転写体上に転写し、直接転写方式においては走行中の転写材上に転写する。これらの各方式を用いたタンデム方式のカラー画像形成装置では、中間転写方式にあっては感光体から画像を受け取り担持する無端状の中間転写ベルトを、直接転写方式にあっては転写材を支持しながら走行する無端状の搬送ベルトを採用するのが一般的である。そして、各感光体には中間転写ベルトあるいは搬送ベルトを感光体に圧接するように転写ローラが配設されている。また、中間転写方式においては、トナー画像が転写された中間転写ベルトに転写材を圧接して転写材に画像を定着するための定着装置である定着ローラ対が設けられている。各転写ローラおよび定着ローラ対の一方には、トナー画像の中間転写ベルトや転写材への転写効率を高めるため、高電圧印されている。
【0004】
しかしながら、特に中間転写ベルトにおいては、その材料が中程度の電気抵抗のある誘電材料で構成されているため、転写ローラの軸方向両端部分と中間転写ベルトとの間においてリークが発生しやすく、その結果転写ローラに印加された高電圧が電圧降下し、電圧が降下した部分に対応したトナー画像が中間転写ベルトや搬送ローラ上の転写材、あるいは定着ローラ対での転写材に転写されない、画像不良が発生しやすい不具合がある。
【0005】
そこで、例えば、特許文献1記載の発明では、転写ローラの軸方向両端に当接する中間転写ベルトの表面に絶縁部材を覆設することが提案されている。また、特許文献2記載の発明では、ローラ端面にカバーを着け、ローラ端部からの沿面リークを防止するようにしている。
【0006】
【特許文献1】
特許第2936812号公報
【0007】
【特許文献2】
特許第3169030号公報
【0008】
【発明が解決しようとする課題】
しかしながら、特許文献1記載の発明では、中間転写ベルトの表面は転写ローラだけでなく感光体や中間転写ベルト清掃装置にも接触しているので、中間転写ベルトに接触する部材よりも外に絶縁部材を設けて接触しないようにすると、その分だけ、中間転写ベルトや装置が大型化してしまう。また、絶縁部材が感光体や中間転写ベルト清掃装置に接触すると、互いに摺擦し合うので、互いに磨耗や捲れが生じ、寿命を長くすることが困難となる。
【0009】
一方、特許文献2記載の発明は、ローラ端部からの沿面リークを防止するようにしてはいるが、中間転写ベルトと中間転写ベルトに電圧を印加するバイアスローラとの間のリークを防止しているではない。
【0010】
感光体と中間転写ベルトとは線速差がないか少ないので、互いに磨耗や捲れは少ない。しかし、感光体の感光層は薄いので、少ない磨耗量でも感光層が薄くなり、中間転写ベルトの絶縁層の端部近傍に対向する場所は感光体基層の導電層と中間転写ベルトとの間でリークが生じ易くなる。その結果、感光体の寿命を長くすることは困難である。
【0011】
また、中間転写ベルトの絶縁部材の位置が中間転写ベルトの清掃装置では、清掃部材の端部または清掃装置容器のトナー漏れ防止シールに対向する位置となり、中間転写ベルトとは線速差が生じる。そこで、中間転写ベルトの絶縁部材の磨耗や捲れが大きくなり、絶縁部材のリーク防止効果に対する寿命を長くすることが困難である。
【0012】
本発明はこのような従来技術の実情に鑑みてなされたもので、その目的は、転写ローラと中間転写ベルトあるいは転写材搬送ベルトとの間で生じるリークを防止して良好な画像を得るとともに、摺擦による磨耗や捲れを防止して装置の長寿命化を図ることができる転写装置及び画像形成装置を提供することである。
【0013】
【課題を解決するための手段】
前記目的を達成するため、第1の手段は、像担持体上のトナー像の極性と逆極性のバイアス電圧が高圧電源から印加された芯金と該芯金の周りを覆う中抵抗層とから構成される1次バイアスローラにより、自らは絶縁性を有しない中間転写ベルトの内面にバイアスを印加し、前記像担持体上のトナー像を該中間転写ベルトに転写し、前記中間転写ベルト上のトナー像の極性と同極性のバイアス電圧が高圧電源から印加された芯金と該芯金の周囲を覆う中抵抗層とから構成される斥力転写バイアスローラにより、前記中間転写ベルトの内面にバイアスを印加し、前記中間転写ベルト上のトナー像を転写材に転写する転写装置であって
前記中間転写ベルトの内面で前記中間転写ベルトの走行により前記1次バイアスローラの中抵抗層の両端面と、さらに、前記斥力転写バイアスローラの中抵抗層の両端面の夫々との対向部となり得る部分の全てに亘るように、前記中間転写ベルトの内面の両端部に帯状の絶縁部材を設けたことを特徴としている。
【0014】
第2の手段は、第1の手段において、前記像担持体は前記中間転写ベルトの走行方向に沿って複数配設され、該複数の像担持体毎に、像担持体上のトナー像の極性と逆極性のバイアス電圧が高圧電源から印加された芯金と該芯金の周りを覆う中抵抗層とから構成される1次バイアスローラにより、自らは絶縁性を有しない中間転写ベルトの内面にバイアスを印加し、前記像担持体上のトナー像を該中間転写ベルトに転写し、前記中間転写ベルト上のトナー像の極性と同極性のバイアス電圧が高圧電源から印加された芯金と該芯金の周囲を覆う中抵抗層とから構成される斥力転写バイアスローラにより、前記中間転写ベルトの内面にバイアスを印加し、前記中間転写ベルト上のトナー像を転写材に転写する転写装置であって、前記中間転写ベルトの走行により前記中間転写ベルトの内面で前記全ての1次バイアスローラの中抵抗層の両端面の夫々と、さらに、前記斥力転写バイアスローラの中抵抗層の両端面の夫々との対向部となり得る部分の全てに亘るように、前記中間転写ベルトの内面の両端部に帯状の絶縁部材を設けたことを特徴としている。
【0015】
第3の手段は、第1の手段又は第2の手段において、前記1次バイアスローラの芯金の周囲を覆う中抵抗層は、前記絶縁部材と接触しないように前記絶縁部材と対向する軸方向両端部の外径が小さくなっていることを特徴としている。
【0016】
第4の手段は、第1の手段から3の手段のいずれかにおいて、前記斥力転写バイアスローラの芯金の周囲を覆う中抵抗層は、前記絶縁部材と接触しないように前記絶縁部材と対向する軸方向両端部の外径が小さくなっていることを特徴としている。
【0017】
第5の手段は、画像データを像担持体に書き込む書き込み手段と、前記書き込み手段により潜像を形成させ、現像して可視画像を形成する画像形成手段と、前記画像形成手段によって可視化された画像を転写材に転写する第1ないし第3の手段に係る転写装置とを備えて構成された画像形成装置を特徴とする。
【0022】
なお、以下の実施形態において、像担持体は感光体40Y,40C,40M,40Kに、被転写体は中間転写ベルト10に、ローラは1次バイアスローラ62Y,62C,62M,62Kに、絶縁部材は絶縁部材203に、芯金は芯金201に、中抵抗層は弾性体202に、斥力転写バイアスローラは斥力転写バイアスローラ16に、書き込み手段は露光装置21に、画像形成手段は画像形成装置18Y,18C,18M,18Kにそれぞれ対応する。
【0023】
【発明の実施の形態】
以下、図面を参照し、本発明の実施の形態について説明する。この実施の形態は、中間転写方式のカラー複写機に適用した場合を例に取っている。図2は本発明の実施の形態に係るカラー複写機の全体構成を概略的に示す図である。
【0024】
図2において、参照番号100は複写装置本体、200はそれを載せる給紙テーブル、300は複写装置本体100上に取り付けるスキャナ、400はさらにその上に取り付ける原稿自動搬送装置(ADF)である。
【0025】
複写装置本体100には、中央に、無端状の中間転写ベルト10が第1、第2の支持ローラ14,15及び斥力転写バイアスローラ16に掛け回されている。そして図2において時計回りに回転搬送可能になっている。この実施の形態においては、第2の支持ローラ15の図において左に、画像転写後に中間転写ベルト10上に残留する残留トナーを除去する中間転写体クリーニング装置17が設けられている。
【0026】
また、第1の支持ローラ14と第2の支持ローラ15間に張り渡された中間転写ベルト10上に、その搬送方向に沿って、イエロー(Y)、シアン(C)、マゼンタ(M)、ブラック(K)の単色画像を形成するための4つの画像形成装置18Y,18C,18M,18Kを横に並べて配置して画像形成部20を構成している。各画像形成装置18Y,18C,18M,18Kは、それぞれドラム状の感光体40Y,40C,40M,40Kとその周囲に配設された帯電装置、現像装置、感光体クリーニング装置、除電装置等の作像ユニットからなる。各感光体40Y,40C,40M,40Kに対向する位置の中間転写ベルト10の裏面に接触するように、1次バイアスローラ62Y,62C,62M,62Kがそれぞれ設けている。その画像形成部20の上には、露光装置21が設けられている。なお、参照番号の後に付けたアルファベットは色彩を表すもので、イエロー用はY、シアン用にC、マゼンタ用はMそしてブラック用はKをつけて区別するものとする。
【0027】
一方、中間転写ベルト10を挟んで画像形成部20と反対の側には、2次転写装置22が備えられている。2次転写装置22は、図示例では、斥力転写バイアスローラ16と、2つのローラ23間に、無端ベルトである2次転写ベルト24を掛け渡すことにより構成されており、2つのローラ23の内の一方のローラ23が中間転写ベルト10を介して斥力転写バイアスローラ16に押し当てるように配置され、中間転写ベルト10上の画像を転写紙(転写材)1上に転写する。
【0028】
2次転写装置22の転写搬送方向下流側には、転写紙上の転写画像を当該転写紙1に定着する定着装置25が設けられている。定着装置25は、無端ベルトである定着ベルト26に加圧ローラ27を押し当てるようにして構成されている。上述した2次転写装置22には、画像転写後の転写紙1をこの定着装置25へと搬送する転写紙搬送機能も備えている。2次転写装置22および定着装置25の下に、画像形成部20と平行に、転写紙1の両面に画像を記録すべく転写紙1を反転する転写紙反転装置28が設けられている。
【0029】
このカラー複写機を用いてコピーをとるときは、原稿自動搬送装置400の原稿台30上に原稿をセットするか、原稿自動搬送装置400を開いてスキャナ300のコンタクトガラス32上に原稿をセットして、原稿自動搬送装置400を閉じてそれで押さえる。
【0030】
そして、スタートスイッチ(図示しない)を押すと、原稿自動搬送装置400に原稿をセットしたときは、原稿を搬送してコンタクトガラス32上へと移動して後、他方コンタクトガラス32上に原稿をセットしたときは、直ちにスキャナ300を駆動し、第1走行体33および第2走行体34を走行する。そして、第1走行体33で光源から光を発射するとともに原稿面からの反射光をさらに反射して第2走行体34に向け、第2走行体34のミラーで反射して結像レンズ35を通して読取りセンサ36に入れ、原稿内容を読み取る。
【0031】
また、上記のスタートスイッチを押すと、駆動ローラである第1の支持ローラ14が回転駆動され、残り2つの従動ローラである第2の支持ローラ15及び斥力転写バイアスローラ16を従動回転し、中間転写ベルト10を回転搬送する。同時に、個々の画像形成手段18でその感光体40を回転して各感光体40上にそれぞれ、ブラック、イエロー、マゼンタ、シアンの単色画像を形成する。そして、中間転写ベルト10の搬送とともに、それらの単色画像を順次転写して中間転写ベルト10上に合成カラー画像を形成する。
【0032】
一方、上記のスタートスイッチを押すと、給紙テーブル200の給紙ローラ42の1つを選択回転し、ペーパーバンク43に多段に備える給紙カセット44の1つから転写紙1を繰り出し、分離ローラ45で1枚ずつ分離して給紙路46に入れ、搬送ローラ47で搬送して複写機本体100内の給紙路48に導き、レジストローラ49に突き当てて止める。給紙はこの外に、給紙ローラ50を回転して手差しトレイ51上の転写紙1を繰り出し、分離ローラ52で1枚ずつ分離して手差し給紙路53に入れ、同じくレジストローラ49に突き当てて止めるようにしてもよい。
【0033】
そして、中間転写ベルト10上の合成カラー画像にタイミングを合わせてレジストローラ49を回転し、中間転写ベルト10と2次転写装置22との間に転写紙1を送り込み、2次転写装置22で転写して転写紙1上にカラー画像を記録する。
【0034】
画像転写後の転写紙1は、2次転写装置22によって定着装置25へと送り込み、定着装置25で熱と圧力とを加えて転写画像を定着した後、切換爪55で切り換えて排出ローラ56で排出し、排紙トレイ57上にスタックする。このとき、切換爪55で切り換えて転写紙反転装置28に入れ、そこで反転して再び転写位置へと導き、裏面にも画像を記録して後、排出ローラ56で排紙トレイ57上に排出するようにもできる。
【0035】
一方、画像転写後の中間転写ベルト10は、中間転写体クリーニング装置17で、画像転写後に中間転写ベルト10上に残留する残留トナーを除去し、画像形成部20による再度の画像形成に備える。なお、レジストローラ49は一般的には接地されて使用されることが多いが、転写紙1の紙粉除去のためにバイアスを印加することも可能である。
【0036】
図1は本発明の実施の形態における特徴部分の一部を詳細に示す斜視図である。この図では、中間転写ベルト10の背面を上方に向けて示している。上述したように、感光体40Y,40C,40M,40Kの各転写位置には転写電界を形成する転写電界形成手段として、1次バイアスローラ62Y,62C,62M,62Kが各感光体40Y,40C,40M,40Kに対向する位置にかつ中間転写ベルト10の裏面に接触するように、それぞれ設けられている。これら1次バイアスローラ62Y,62C,62M,62Kは、導電性の芯金201と中抵抗のゴム等で構成された弾性体202で構成されている。1次バイアスローラ62Y,62C,62M,62Kの各芯金201は、作像時は図示しない高圧電源から感光体40Y,40C,40M,40K上のトナー像とは逆極性の電圧を印加される。斥力転写バイアスローラ16も、1次バイアスローラ62Y,62C,62M,62Kと同様に、芯金201と中抵抗のゴム等で作られた弾性体202で構成され、作像時は芯金201に図示しない高圧電源から中間転写ベルト10上のトナー像と同極性の電圧を印加される。
【0037】
中間転写ベルト10の走行方向に直交する方向の両端部(中間転写ベルトの両縁部)で、かつ画像面より外側の画像形成面に対して背面(中間転写ベルトの内側)には、ポリエチレン、ポリエステル等で構成された帯状の絶縁部材203が設けられている。感光体40Y,40C,40M,40Kと対向する位置に配設された4本の1次バイアスローラ62Y,62C,62M,62Kと1本の斥力転写バイアスローラ16の合計5本のローラの軸方向両端部は全て中間転写ベルト10背面の絶縁部材203に接触するように配置されている。
【0038】
このように4本の1次バイアスローラ62Y,62C,62M,62Kと1本の斥力バイアスローラ16の各軸方両端部は、中間転写ベルト10の内側の面に設けられた絶縁部材203に接触しているので、これらローラからの電圧のリークを防止することができるとともに、絶縁部材203は第1、第2の支持ローラ14,15、斥力転写バイアスローラ16及び1次バイアスローラ62Y,62C,62M,62K以外には接触することがなく、中間転写ベルト10を引張する第1、第2の支持ローラ14,15及び斥力転写バイアスローラ16と中間転写ベルト10は線速差なく連れ回るので、絶縁部材203の磨耗は少なく、絶縁部材203によるリーク防止効果を長く保持することができる。更に、全てのバイアスローラに対してそれぞれにリーク防止部材を設ける必要はなく、一つのリーク防止部材で全てのバイアスローラの軸方向端面のリークを防止できるので、安価で小スペースの構成とすることができる。
【0039】
なお、中間転写ベルト10を引っ張る第1、第2の支持ローラ14,15及び斥力転写バイアスローラ16の軸方向端部の絶縁部材203に対向する部分の外径を小さくして、絶縁部材203と接触しないようにすることによって、さらに寿命を長くすることができる。
【0040】
上述した実施の形態はカラー複写機のうちの間接方式を例にとっているが、従来技術で説明した直接方式のカラー複写機においても、バイアスローラを備えた複写機であれば、本発明を適用することができる。
【0041】
【発明の効果】
以上のように、本発明によれば、絶縁部材を被転写体の裏面に設けているので、絶縁部材はバイアスローラ以外に接触することとなるが、被転写体を回転駆動するローラと被転写体は線速差なく連れ回るので、磨耗は少なく、絶縁部材のリーク防止効果に対する寿命を長くすることができる。
【図面の簡単な説明】
【図1】本発明の実施の形態における特徴部分の一部を詳細に示す斜視図である。
【図2】本発明の実施の形態に係るカラー複写機の全体構成を概略的に示す図である。
【符号の説明】
10 中間転写ベルト
16 斥力転写バイアスローラ
18Y,18C,18M,18K 画像形成手段
20 タンデム画像形成部
22 ニ次転写装置
25 定着装置
40Y,40C,40M,40K 感光体
62Y,62C,62M,62K 1次バイアスローラ
100 複写装置本体
200 給紙テーブル
300 スキャナ
201 芯金
202 弾性体
203 絶縁部材
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transfer apparatus and an image forming apparatus that transfer a toner image to a transfer target by a roller to which a bias voltage is applied.
[0002]
[Prior art]
An electrophotographic image forming apparatus that forms an electrostatic latent image on a photosensitive member with a laser beam or the like in accordance with an image signal, and transfers the electrostatic latent image to a transfer material or the like as a toner image is a copier, printer Widely used in facsimiles. In recent years, a color image forming apparatus for transferring a color image to a transfer material or the like using a color image signal has also been provided.
[0003]
A typical method of color image formation includes an intermediate transfer method in which toner images of different colors formed on a plurality of photosensitive members are transferred while being superimposed on an intermediate transfer member, and then transferred to a transfer material in a batch. There is a direct transfer system in which toner images of different colors formed on a photoconductor as an image carrier are transferred while being directly superimposed on a transfer material. Since a plurality of photoconductors are arranged side by side facing a transfer material or an intermediate transfer body, this is called a tandem method, and yellow (Y), magenta (M), cyan (C), and black (K) for each photoconductor. For each color, an electrophotographic process such as electrostatic latent image formation and development is executed, and the image is transferred onto a running intermediate transfer member in the intermediate transfer method, and transferred onto a running transfer material in the direct transfer method. To do. The tandem color image forming apparatus using each of these methods supports an endless intermediate transfer belt that receives and carries an image from a photoreceptor in the intermediate transfer method, and supports a transfer material in the direct transfer method. In general, an endless conveyor belt that travels while moving is employed. Each photoconductor is provided with a transfer roller so that the intermediate transfer belt or the conveyance belt is pressed against the photoconductor. In the intermediate transfer system, a fixing roller pair is provided as a fixing device for fixing the image on the transfer material by pressing the transfer material on the intermediate transfer belt on which the toner image is transferred. One of each transfer roller and fixing roller pair is marked with a high voltage in order to increase the transfer efficiency of the toner image to the intermediate transfer belt or transfer material.
[0004]
However, especially in the intermediate transfer belt, since the material is made of a dielectric material having a moderate electrical resistance, leakage is likely to occur between the axial end portions of the transfer roller and the intermediate transfer belt. As a result, the high voltage applied to the transfer roller drops, and the toner image corresponding to the voltage drop is not transferred to the transfer material on the intermediate transfer belt or transport roller, or to the transfer material on the fixing roller pair. There is a problem that is likely to occur.
[0005]
Therefore, for example, in the invention described in Patent Document 1, it is proposed to cover an insulating member on the surface of the intermediate transfer belt that contacts both ends of the transfer roller in the axial direction. Further, in the invention described in Patent Document 2, a cover is attached to the roller end surface to prevent creeping leakage from the roller end portion.
[0006]
[Patent Document 1]
Japanese Patent No. 2936812 [0007]
[Patent Document 2]
Japanese Patent No. 3169030 [0008]
[Problems to be solved by the invention]
However, in the invention described in Patent Document 1, since the surface of the intermediate transfer belt is in contact with not only the transfer roller but also the photosensitive member and the intermediate transfer belt cleaning device, the insulating member is provided outside the member that contacts the intermediate transfer belt. If the belt is provided so as not to come into contact, the intermediate transfer belt and the apparatus are enlarged accordingly. Further, when the insulating member comes into contact with the photosensitive member or the intermediate transfer belt cleaning device, they are rubbed against each other, so that they are worn out or twisted, making it difficult to extend the life.
[0009]
On the other hand, the invention described in Patent Document 2 prevents creeping leakage from the roller end, but prevents leakage between the intermediate transfer belt and the bias roller that applies a voltage to the intermediate transfer belt. Not.
[0010]
There is little or no difference in linear velocity between the photoconductor and the intermediate transfer belt, so there is little wear or twist. However, since the photosensitive layer of the photosensitive member is thin, the photosensitive layer becomes thin even with a small amount of wear, and the place facing the vicinity of the end of the insulating layer of the intermediate transfer belt is between the conductive layer of the photosensitive member base layer and the intermediate transfer belt. Leakage is likely to occur. As a result, it is difficult to extend the life of the photoreceptor.
[0011]
Further, in the intermediate transfer belt cleaning device, the position of the insulating member of the intermediate transfer belt is a position facing the end of the cleaning member or the toner leakage prevention seal of the cleaning device container, and a linear velocity difference is generated from the intermediate transfer belt. Therefore, the insulating member of the intermediate transfer belt is greatly worn and twisted, and it is difficult to extend the life of the insulating member for preventing leakage.
[0012]
The present invention has been made in view of such a state of the art, and its purpose is to prevent leakage between the transfer roller and the intermediate transfer belt or the transfer material conveying belt and obtain a good image, It is an object of the present invention to provide a transfer device and an image forming apparatus capable of preventing the wear and wrinkling due to rubbing and extending the life of the apparatus.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the first means includes a core metal to which a bias voltage having a polarity opposite to the polarity of the toner image on the image carrier is applied from a high voltage power source, and an intermediate resistance layer covering the periphery of the core metal. The primary bias roller is configured to apply a bias to the inner surface of the intermediate transfer belt, which does not have insulation, and transfer the toner image on the image carrier to the intermediate transfer belt. A bias is applied to the inner surface of the intermediate transfer belt by a repulsive transfer bias roller composed of a core bar to which a bias voltage having the same polarity as that of the toner image is applied from a high-voltage power source and an intermediate resistance layer covering the periphery of the core bar. A transfer device for applying and transferring a toner image on the intermediate transfer belt to a transfer material ,
By the running of the intermediate transfer belt on the inner surface of the intermediate transfer belt, both end surfaces of the intermediate resistance layer of the primary bias roller can be opposed to both end surfaces of the intermediate resistance layer of the repulsive transfer bias roller. A belt-like insulating member is provided at both ends of the inner surface of the intermediate transfer belt so as to cover the entire portion.
[0014]
Second means, in the first means, the image bearing member is a plurality arranged along the running direction of the intermediate transfer belt, each image bearing member of the plurality, the polarity of the toner image on the image bearing member reverse the polarity of the bias voltage by the primary bias rollers composed of a resistive layer in covering around the metal core and metal core that has been applied from high-voltage power supply, while themselves during have such an insulating property transfer belt A core bar to which a bias voltage having the same polarity as the polarity of the toner image on the intermediate transfer belt is applied from a high-voltage power source is applied to the inner surface of the image transfer member to transfer the toner image on the image carrier to the intermediate transfer belt. And a repulsive transfer bias roller comprising a middle resistance layer covering the periphery of the metal core, a bias is applied to the inner surface of the intermediate transfer belt and a toner image on the intermediate transfer belt is transferred to a transfer material a is, the intermediate transfer bell And each traveling through both end surfaces in the resistance layer of the intermediate transfer belt wherein all the primary bias rollers on the inner surface of the further, can be a portion facing the respective end surfaces of the resistance layer in said repulsive bias roller A belt-like insulating member is provided at both ends of the inner surface of the intermediate transfer belt so as to cover the entire portion.
[0015]
The third means is an axial direction in which the intermediate resistance layer covering the periphery of the core metal of the primary bias roller is opposed to the insulating member in the first means or the second means so as not to contact the insulating member. It is characterized in that the outer diameters at both ends are small .
[0016]
According to a fourth means, in any one of the first to third means, the middle resistance layer covering the periphery of the core of the repulsive force transfer bias roller faces the insulating member so as not to contact the insulating member. It is characterized in that the outer diameters at both ends in the axial direction are reduced .
[0017]
The fifth means is a writing means for writing image data on an image carrier, an image forming means for forming a latent image by the writing means and developing it to form a visible image, and an image visualized by the image forming means. And an image forming apparatus configured to include a transfer device according to first to third means for transferring the image onto a transfer material .
[0022]
In the following embodiments, the image carrier is the photoreceptors 40Y, 40C, 40M, and 40K, the transfer body is the intermediate transfer belt 10, the rollers are the primary bias rollers 62Y, 62C, 62M, and 62K, and the insulating member. Is the insulating member 203, the core is the core 201, the middle resistance layer is the elastic body 202, the repulsive transfer bias roller is the repulsive transfer bias roller 16, the writing means is the exposure device 21, and the image forming means is the image forming apparatus. 18Y, 18C, 18M, and 18K respectively.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the case where the present invention is applied to an intermediate transfer type color copying machine is taken as an example. FIG. 2 is a diagram schematically showing the overall configuration of the color copying machine according to the embodiment of the present invention.
[0024]
In FIG. 2, reference numeral 100 is a copying apparatus main body, 200 is a paper feed table on which it is placed, 300 is a scanner mounted on the copying apparatus main body 100, and 400 is an automatic document feeder (ADF) mounted thereon.
[0025]
In the copying apparatus main body 100, an endless intermediate transfer belt 10 is wound around the first and second support rollers 14 and 15 and the repulsive force transfer bias roller 16 at the center. In FIG. 2, it can be rotated and conveyed clockwise. In this embodiment, an intermediate transfer member cleaning device 17 for removing residual toner remaining on the intermediate transfer belt 10 after image transfer is provided on the left side of the second support roller 15 in the drawing.
[0026]
Further, on the intermediate transfer belt 10 stretched between the first support roller 14 and the second support roller 15, along the conveyance direction, yellow (Y), cyan (C), magenta (M), Four image forming apparatuses 18Y, 18C, 18M, and 18K for forming a black (K) monochrome image are arranged side by side to constitute the image forming unit 20. Each of the image forming apparatuses 18Y, 18C, 18M, and 18K includes a drum-shaped photoconductor 40Y, 40C, 40M, and 40K, and a charging device, a developing device, a photoconductor cleaning device, a static eliminator, and the like disposed around the photoconductors. It consists of an image unit. Primary bias rollers 62Y, 62C, 62M, and 62K are provided so as to come into contact with the back surface of the intermediate transfer belt 10 at positions facing the photoconductors 40Y, 40C, 40M, and 40K, respectively. An exposure device 21 is provided on the image forming unit 20. The alphabet after the reference number represents a color, and is distinguished by adding Y for yellow, C for cyan, M for magenta, and K for black.
[0027]
On the other hand, a secondary transfer device 22 is provided on the opposite side of the intermediate transfer belt 10 from the image forming unit 20. In the illustrated example, the secondary transfer device 22 is configured by spanning a secondary transfer belt 24 that is an endless belt between a repulsive transfer bias roller 16 and two rollers 23. One of the rollers 23 is disposed so as to press against the repulsive transfer bias roller 16 via the intermediate transfer belt 10, and the image on the intermediate transfer belt 10 is transferred onto the transfer paper (transfer material) 1.
[0028]
A fixing device 25 for fixing the transfer image on the transfer paper to the transfer paper 1 is provided downstream of the secondary transfer device 22 in the transfer conveyance direction. The fixing device 25 is configured to press a pressure roller 27 against a fixing belt 26 that is an endless belt. The secondary transfer device 22 described above also has a transfer paper transport function for transporting the transfer paper 1 after image transfer to the fixing device 25. Under the secondary transfer device 22 and the fixing device 25, a transfer paper reversing device 28 for reversing the transfer paper 1 to record images on both sides of the transfer paper 1 is provided in parallel with the image forming unit 20.
[0029]
When making a copy using this color copying machine, set the document on the document table 30 of the automatic document feeder 400 or open the automatic document feeder 400 and set the document on the contact glass 32 of the scanner 300. Then, the automatic document feeder 400 is closed and pressed by it.
[0030]
When a start switch (not shown) is pressed, when a document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. When this occurs, the scanner 300 is immediately driven to travel on the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.
[0031]
When the start switch is pressed, the first support roller 14 that is a drive roller is driven to rotate, and the remaining two follower rollers 15 and the repulsive transfer bias roller 16 are driven and rotated. The transfer belt 10 is rotated and conveyed. At the same time, the individual image forming means 18 rotates the photoconductor 40 to form black, yellow, magenta, and cyan monochrome images on each photoconductor 40. Then, along with the conveyance of the intermediate transfer belt 10, the monochrome images are sequentially transferred to form a composite color image on the intermediate transfer belt 10.
[0032]
On the other hand, when the start switch is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, the transfer paper 1 is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, and the separation roller The sheet is separated one by one at 45 and put into the sheet feeding path 46, conveyed by the conveying roller 47, guided to the sheet feeding path 48 in the copying machine main body 100, abutted against the registration roller 49 and stopped. In addition to this, the sheet feeding roller 50 is rotated to feed the transfer paper 1 on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and pushed against the registration roller 49. You may make it stop.
[0033]
Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 10, the transfer paper 1 is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. Then, a color image is recorded on the transfer paper 1.
[0034]
The transfer paper 1 after image transfer is fed to the fixing device 25 by the secondary transfer device 22, and heat and pressure are applied by the fixing device 25 to fix the transferred image, and then the switching paper 55 is switched by the switching claw 55 and discharged by the discharge roller 56. The paper is discharged and stacked on the paper discharge tray 57. At this time, it is switched by the switching claw 55 and is put into the transfer paper reversing device 28, where it is reversed and led again to the transfer position, an image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56. You can also
[0035]
On the other hand, the intermediate transfer belt 10 after image transfer is removed by the intermediate transfer body cleaning device 17 to remove residual toner remaining on the intermediate transfer belt 10 after image transfer, and prepares for image formation by the image forming unit 20 again. In general, the registration roller 49 is often used while being grounded. However, a bias can be applied to remove the paper dust of the transfer paper 1.
[0036]
FIG. 1 is a perspective view showing in detail a part of the characteristic part in the embodiment of the present invention. In this figure, the back surface of the intermediate transfer belt 10 is shown facing upward. As described above, the primary bias rollers 62Y, 62C, 62M, and 62K serve as the transfer electric field forming means for forming transfer electric fields at the transfer positions of the photoconductors 40Y, 40C, 40M, and 40K. They are provided at positions facing 40M and 40K so as to contact the back surface of the intermediate transfer belt 10, respectively. These primary bias rollers 62Y, 62C, 62M, and 62K are composed of a conductive core bar 201 and an elastic body 202 made of a medium resistance rubber or the like. The cores 201 of the primary bias rollers 62Y, 62C, 62M, and 62K are applied with a voltage having a polarity opposite to that of the toner images on the photoreceptors 40Y, 40C, 40M, and 40K from a high voltage power source (not shown) during image formation. . Similarly to the primary bias rollers 62Y, 62C, 62M, and 62K, the repulsive force transfer bias roller 16 includes a cored bar 201 and an elastic body 202 made of a medium resistance rubber or the like. A voltage having the same polarity as the toner image on the intermediate transfer belt 10 is applied from a high voltage power source (not shown).
[0037]
On both ends of the intermediate transfer belt 10 in the direction orthogonal to the running direction (both edges of the intermediate transfer belt) and on the back surface (inner side of the intermediate transfer belt) with respect to the image forming surface outside the image surface, polyethylene, A strip-shaped insulating member 203 made of polyester or the like is provided. Axial direction of a total of five rollers including four primary bias rollers 62Y, 62C, 62M and 62K and one repulsive transfer bias roller 16 disposed at positions facing the photoconductors 40Y, 40C, 40M and 40K. Both end portions are arranged so as to contact the insulating member 203 on the back surface of the intermediate transfer belt 10.
[0038]
Thus, the axial end portions of the four primary bias rollers 62Y, 62C, 62M, and 62K and the single repulsive bias roller 16 are in contact with the insulating member 203 provided on the inner surface of the intermediate transfer belt 10. Therefore, the leakage of voltage from these rollers can be prevented, and the insulating member 203 includes the first and second support rollers 14 and 15, the repulsive transfer bias roller 16, and the primary bias rollers 62Y, 62C, The first and second support rollers 14 and 15 that pull the intermediate transfer belt 10 and the repulsive transfer bias roller 16 and the intermediate transfer belt 10 are rotated without any difference in linear speed. There is little abrasion of the insulating member 203, and the leak prevention effect by the insulating member 203 can be kept long. Furthermore, it is not necessary to provide a leak prevention member for each of the bias rollers, and a leak prevention member can prevent leakage of the end surfaces in the axial direction of all the bias rollers. Can do.
[0039]
Note that the outer diameters of the first and second support rollers 14 and 15 that pull the intermediate transfer belt 10 and the end portions in the axial direction of the repulsive transfer bias roller 16 that face the insulating member 203 are reduced so that the insulating member 203 By preventing contact, the life can be further extended.
[0040]
In the above-described embodiment, the indirect method of the color copying machine is taken as an example, but the present invention is applied to the direct method color copying machine described in the prior art as long as it is a copying machine having a bias roller. be able to.
[0041]
【The invention's effect】
As described above, according to the present invention, since the insulating member is provided on the back surface of the transferred object, the insulating member comes in contact with a part other than the bias roller. Since the body rotates with no difference in linear velocity, there is little wear and the life of the insulating member for preventing leakage can be extended.
[Brief description of the drawings]
FIG. 1 is a perspective view showing in detail a part of a characteristic part in an embodiment of the present invention.
FIG. 2 is a diagram schematically showing an overall configuration of a color copying machine according to an embodiment of the present invention.
[Explanation of symbols]
10 Intermediate transfer belt 16 Repulsive transfer bias rollers 18Y, 18C, 18M, 18K Image forming means 20 Tandem image forming unit 22 Secondary transfer device 25 Fixing devices 40Y, 40C, 40M, 40K Photoconductors 62Y, 62C, 62M, 62K Primary Bias roller 100 Copier main body 200 Paper feed table 300 Scanner 201 Core metal 202 Elastic body 203 Insulating member

Claims (5)

像担持体上のトナー像の極性と逆極性のバイアス電圧が高圧電源から印加された芯金と該芯金の周りを覆う中抵抗層とから構成される1次バイアスローラにより、自らは絶縁性を有しない中間転写ベルトの内面にバイアスを印加し、前記像担持体上のトナー像を該中間転写ベルトに転写し、前記中間転写ベルト上のトナー像の極性と同極性のバイアス電圧が高圧電源から印加された芯金と該芯金の周囲を覆う中抵抗層とから構成される斥力転写バイアスローラにより、前記中間転写ベルトの内面にバイアスを印加し、前記中間転写ベルト上のトナー像を転写材に転写する転写装置であって
前記中間転写ベルトの内面で前記中間転写ベルトの走行により前記1次バイアスローラの中抵抗層の両端面と、さらに、前記斥力転写バイアスローラの中抵抗層の両端面の夫々との対向部となり得る部分の全てに亘るように、前記中間転写ベルトの内面の両端部に帯状の絶縁部材を設けたことを特徴とする転写装置。
The primary bias roller is composed of a core metal to which a bias voltage having a polarity opposite to the polarity of the toner image on the image carrier is applied from a high-voltage power source, and a middle resistance layer covering the core metal. A bias voltage is applied to the inner surface of the intermediate transfer belt that does not have the toner, the toner image on the image carrier is transferred to the intermediate transfer belt, and a bias voltage having the same polarity as the polarity of the toner image on the intermediate transfer belt is a high voltage power source. A bias is applied to the inner surface of the intermediate transfer belt by a repulsive transfer bias roller composed of a cored bar applied from and a middle resistance layer covering the periphery of the cored bar to transfer the toner image on the intermediate transfer belt A transfer device for transferring to a material ,
By the running of the intermediate transfer belt on the inner surface of the intermediate transfer belt, both end surfaces of the intermediate resistance layer of the primary bias roller can be opposed to both end surfaces of the intermediate resistance layer of the repulsive transfer bias roller. A transfer apparatus comprising a band-shaped insulating member provided at both ends of the inner surface of the intermediate transfer belt so as to cover the entire portion.
前記像担持体は前記中間転写ベルトの走行方向に沿って複数配設され、該複数の像担持体毎に、像担持体上のトナー像の極性と逆極性のバイアス電圧が高圧電源から印加された芯金と該芯金の周りを覆う中抵抗層とから構成される1次バイアスローラにより、自らは絶縁性を有しない中間転写ベルトの内面にバイアスを印加し、前記像担持体上のトナー像を該中間転写ベルトに転写し、前記中間転写ベルト上のトナー像の極性と同極性のバイアス電圧が高圧電源から印加された芯金と該芯金の周囲を覆う中抵抗層とから構成される斥力転写バイアスローラにより、前記中間転写ベルトの内面にバイアスを印加し、前記中間転写ベルト上のトナー像を転写材に転写する転写装置であって、
前記中間転写ベルトの走行により前記中間転写ベルトの内面で前記全ての1次バイアスローラの中抵抗層の両端面の夫々と、さらに、前記斥力転写バイアスローラの中抵抗層の両端面の夫々との対向部となり得る部分の全てに亘るように、前記中間転写ベルトの内面の両端部に帯状の絶縁部材を設けたことを特徴とする請求項1記載の転写装置。
Said image bearing member is a plurality arranged along the running direction of the intermediate transfer belt, each image bearing member of the plurality of bias voltages of polarity opposite the polarity of the toner image on the image bearing member is applied from a high voltage power source by the primary bias rollers composed of a resistive layer in covering around the metal core and metal core, itself has a bias is applied to the inner surface of the stomach during the transfer belts has an insulating property, the image bearing member A core metal to which a bias voltage having the same polarity as the polarity of the toner image on the intermediate transfer belt is applied from a high voltage power source and an intermediate resistance layer covering the periphery of the core metal; A transfer device configured to apply a bias to the inner surface of the intermediate transfer belt by a repulsive transfer bias roller configured by transferring a toner image on the intermediate transfer belt to a transfer material ;
Due to the running of the intermediate transfer belt, both end surfaces of the intermediate resistance layers of all the primary bias rollers on the inner surface of the intermediate transfer belt, and further, both end surfaces of the intermediate resistance layers of the repulsive transfer bias roller, respectively. The transfer apparatus according to claim 1, wherein strip-shaped insulating members are provided at both end portions of the inner surface of the intermediate transfer belt so as to cover all the portions that can be opposed portions.
前記1次バイアスローラの芯金の周囲を覆う中抵抗層は、前記絶縁部材と接触しないように前記絶縁部材と対向する軸方向両端部の外径が小さくなっていることを特徴とする請求項1または2に記載の転写装置。 Resistive layer in covering the periphery of the core metal of the primary bias roller claims, characterized in that the outer diameter of the axial end portion of the insulating member and the counter so as not to contact with the insulating member is smaller The transfer apparatus according to 1 or 2 . 前記斥力転写バイアスローラの芯金の周囲を覆う中抵抗層は、前記絶縁部材と接触しないように前記絶縁部材と対向する軸方向両端部の外径が小さくなっていることを特徴とする請求項1から3のいずれか1項に記載の転写装置。 Resistive layer in covering the periphery of the metal core of the repulsive transfer bias roller, billed, characterized in that the outer diameter of the axial end portion of the insulating member and the counter so as not to contact with the insulating member is smaller Item 4. The transfer device according to any one of Items 1 to 3 . 画像データを像担持体に書き込む書き込み手段と、
前記書き込み手段により潜像を形成させ、現像して可視画像を形成する画像形成手段と、
前記画像形成手段によって可視化された画像を転写材に転写する請求項1から4のいずれか1項に記載の転写装置と、
を備えたことを特徴とする画像形成装置
Writing means for writing image data to the image carrier;
An image forming means for forming a latent image by the writing means and developing to form a visible image;
The transfer device according to claim 1, wherein the image visualized by the image forming unit is transferred to a transfer material;
An image forming apparatus comprising the.
JP2003181436A 2003-06-25 2003-06-25 Transfer device and image forming apparatus Expired - Fee Related JP4336152B2 (en)

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