JP2004258104A - Fixing device and image forming apparatus - Google Patents

Fixing device and image forming apparatus Download PDF

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Publication number
JP2004258104A
JP2004258104A JP2003045861A JP2003045861A JP2004258104A JP 2004258104 A JP2004258104 A JP 2004258104A JP 2003045861 A JP2003045861 A JP 2003045861A JP 2003045861 A JP2003045861 A JP 2003045861A JP 2004258104 A JP2004258104 A JP 2004258104A
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Prior art keywords
fixing roller
roller
fixing
reinforcing
pressing member
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JP2003045861A
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Japanese (ja)
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JP4110010B2 (en
Inventor
Kenji Ishii
賢治 石井
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Ricoh Co Ltd
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Ricoh Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device that prevents deformation of a fixing roller at low costs and makes a nip between the fixing roller and a pressure roller uniform, thereby improving fixing performance, and to provide an image forming apparatus. <P>SOLUTION: The fixing roller 1 has in it reinforcement ribs 9 that restrict deformation of the roller. The warp restricting device 10 having a pressing member 11 which is disposed opposite the pressure roller 2 and abuts on the peripheral face of the fixing roller 1 in order to restrict warp of the fixing roller 1 due to the press-contact of the pressure roller 2, is arranged. The pressing member 11 of the warp restricting device is positioned corresponding to the reinforcement ribs 9 in the fixing roller in the roller axial direction. Thus, while crush of the fixing roller in a radial direction is prevented by the reinforcement ribs 9, deformation of the fixing roller is prevented by hindering the fixing roller from warping and deforming in the axial direction. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【0001】
【発明の属する技術分野】
本発明は、複写機、プリンタ、ファクシミリ等の画像形成装置における定着装置に関するものである。
【0002】
【従来の技術】
【特許文献1】特開平09−171321号公報
【特許文献2】特開平09−212026号公報
【特許文献3】特開2002−106547号公報
【特許文献4】特開2001−296770号公報
【0003】
昨今の環境改善活動の高まりや省エネ法の制定等、画像形成装置の分野においても省エネルギーへの対応が近年強く求められてきている。画像形成装置内部に着目すると、熱定着装置はエネルギー消費量が多く、エネルギー効率の改善に向けて様々な技術が提案・実施されている。
【0004】
エネルギー効率の改善例として、画像形成装置の未使用時には定着ローラの待機温度を下げ、エネルギー消費効率を改善する方法がある。しかし、この方法によると、使用時に定着装置のウォームアップに時間がかかり、ユーザが直ぐに作業を行えない等の弊害が生じてしまう。
【0005】
これに対して、例えば定着ローラ温度の上昇率を大きくする(温度上昇率の大きな定着ローラを使用する)ことによって、待機時には低温度を維持し、使用時には所定温度までの到達時間=ウォームアップ時間を短縮することが可能である。ウォームアップ時間を短縮する方法として、前述のように温度上昇率を高めれば良い訳だが、その方法のひとつとして定着ローラ芯金に薄肉の金属パイプのような熱容量の小さい部材を用いたものが近年多く用いられている。
【0006】
ところが、いたずらに定着ローラの芯金を薄肉化すると機械的強度が低下し、定着ローラ長手方向の撓みや、定着ローラ断面が潰れる等の変形の問題が生じてしまう。このような定着ローラの変形が発生すると、定着ローラと加圧ローラとで形成されるニップが軸方向中央部において狭くなってしまい、所望のニップ幅を得られないために定着不良が発生したり、搬送中央部と端部の線速差によって用紙シワを発生させる等の様々な不具合が発生してしまう。
【0007】
すなわち薄肉ローラのように機械的強度の弱いローラの場合、図8に示すように定着ローラ1に加圧ローラ2を圧接させた場合、定着ローラ1は軸方向の撓みによりローラ中央部で撓み量dが発生し、同時に図9に示すような径方向断面の潰れ(潰れ量=H1−H2)を引き起こしてしまう。この変形は従来の定着装置においても少なからず発生していたのだが、上述のように省エネ対応の薄肉定着ローラにおいてはその変形量の大きさにより、画像品質上の問題として重要視されるようになっている。
【0008】
図10のグラフに径φ40mm、厚さt=0.3mm、材質がアルミニウム製の定着ローラの上面及び下面の変位及び定着ローラの加圧方向の外径潰れ量の測定結果を示す。荷重(加圧力)増加とともに定着ローラの軸方向の撓みが発生し、下面の位置(図10中の下面変位量)は上昇するのに対して、径方向の断面の潰れが顕著であるため、定着ローラ上面の位置(図10中の上面変位量)は逆に荷重とともに下がってきている。この変形により、上述のようにローラ軸方向中央において圧力が下がり、ニップが狭くなって均一なニップが形成できず、従って定着不良を起こしてしまう。
【0009】
これらの問題を解決する方法として、特許文献1や特許文献2に開示されているように、定着ローラの外部あるいは内部に補強部材を設ける構造が提案されている。
【0010】
特許文献1に開示されている技術は、定着ローラ長手方向のたわみを解消しようとするものであり、加圧ローラに対してその外側から補強ローラを接触させ、スプリングでたわみを小さくする方向へ付勢し、加圧ローラを補強している。加圧ローラの中央部のみに補助ローラを設ける技術も開示している。
【0011】
また特許文献2に開示の技術は、ローラ断面方向のつぶれについて解消しようとするものであり、定着ローラ内に補強のためのリングを複数個装填して構成してある。
【0012】
ところで、定着ローラ内に補強のためのリングを装填すれば、定着ローラのたわみや断面のつぶれを大幅に削減することができるが、補強部材を装填した場合にはいくつかの新たな問題が生じ得る。
【0013】
すなわち、
▲1▼ 定着ローラに補強部材を固定することが困難である。
▲2▼ 定着ローラの変形を防止するための補強部材には大きな荷重が掛かるため、定着ローラにしっかりと固定しておかなければ定着ローラ内ですぐに外れてしまう。
▲3▼ 補強部材をシマリバメ状態で定着ローラ内に固定する場合、補強部材に高い精度が求められ、装填作業にも技術を要する。
▲4▼ また溶接等で定着ローラ内に固定する場合、加工コストが掛かるだけでなく溶接部に荷重が集中し、補強リングの破損の原因となる。
▲5▼ 定着ローラ内側に別部材が入っているため、熱容量が局所的に大きくなり、その部分の昇温が遅くなってしまう。
▲6▼ 補強部材のために定着ローラの熱源の構成が制限される(例えば、内部のハロゲンヒータで定着ローラを加熱する場合は、内側の補強部材を加熱してから芯金に熱伝導することとなり、熱応答性の遅れが発生する)。
等々である。
【0014】
【発明が解決しようとする課題】
そこで、これらの問題に対し、例えば特許文献3には、定着ローラの内面に絞り加工によって定着ローラの高剛性を得る補強リブを設けることが開示されている。この技術によれば円周方向の潰れに対しては効果的であるが、軸方向の撓みに対しては限界があり、特に高速機に展開した場合に高荷重条件によっては撓みを防止するには限界があるのが現状である。また、前述のリブの形状、リブ高さ、本数等を増強し、撓み・潰れを防止することは可能であるが、その分、定着ローラの熱容量が増えてウォームアップ時間の短縮効果が低減するばかりでなく、上記不具合点▲5▼で述べたように、局所的に熱容量が大きくなりその部分の昇温が遅くなるという欠点があった。
【0015】
また、特許文献4に開示の技術は、定着ローラの撓み方向、潰れ方向各々に撓み防止のコロを設けて前記不具合を解消した例である。しかし、この技術によると、定着ローラの撓み・潰れを複数のコロで押さえる構成であるため、コロの熱容量により接触部分で局所的に昇温が遅くなってしまったり、定着ローラの撓み・潰れを抑える方向にコロを設け、夫々の強固な構造体に取りつける必要があり、コストアップを招いてしまうという問題があった。
【0016】
本発明は、従来の定着装置・画像形成装置における上述の問題を解決し、低コストに定着ローラの変形を防ぎ、加圧ローラとのニップを均一化して定着性能を向上することのできる定着装置及び画像形成装置を提供することを課題とする。
【0017】
【課題を解決するための手段】
前記の課題は、本発明により、円筒状の定着ローラと該定着ローラに圧接される加圧ローラとを有する定着装置において、前記定着ローラはローラ内部にローラの変形を規制するための補強部材または補強部を有し、前記加圧ローラと反対側で前記定着ローラ外周面に当接する少なくとも1つの押圧部材を有して、前記加圧ローラの圧接による前記定着ローラの撓みを規制する撓み規制装置を設け、前記撓み規制装置の押圧部材の前記定着ローラ軸方向の位置を、定着ローラ内部の前記補強部材または補強部に一致させることにより解決される。
【0018】
また、前記の課題を解決するため、本発明は、前記押圧部材が円筒形断面形状で回転可能に支持され、前記定着ローラに接触して回転することを提案する。
また、前記の課題を解決するため、本発明は、前記押圧部材の外周面に接触する清掃部材と、該清掃部材により清掃・回収した付着物を収容する付着物回収部とを設けることを提案する。
【0019】
また、前記の課題は、本発明により、請求項1〜3のいずれか1項に記載の定着装置を備える画像形成装置により解決される。
【0020】
【発明の実施の形態】
以下、本発明の実施の形態を図面に基づいて説明する。
図1,2は、本発明に係る定着装置の一例における要部を示す径方向の断面図及び軸方向の断面図である。
【0021】
これらの図において、定着ローラ1は、断熱ブッシュ3、定着ローラ軸受4を介して定着側板5に回動自在に支持されており、定着ローラの一方側端部に取りつけた歯車6が、図示しない駆動源と噛み合って回転駆動力を受けるようになっている。本例では、定着ローラ1の材質は、アルミまたは鉄の薄肉パイプを基体とし、肉厚は0.3〜2.0mm程度で、外周表面にはフッ素樹脂等の離型層が形成してあり、内部にはハロゲンヒータ7が配設されている。
【0022】
なお、図示は省略するが、定着ローラ1の周面には温度センサが接触又は近接配置してあり、この温度センサにより検出した定着ローラ1の温度を基にハロゲンヒータ7への通電を制御するようになっている。通常は、画像形成装置の電源を投入するとハロゲンヒータ7へ電流が流れ、定着ローラ1の温度は180℃前後の設定温度まで急激に上昇するようになっている。
【0023】
定着ローラ1に圧接される加圧ローラ2と反対側で、定着ローラの外周に接するように撓み防止装置10が設けられている。この撓み防止装置10は、半円状に突出して定着ローラ1に押圧される押圧部11aを有する押圧部材11と、その押圧部材11を保持する保持部材12と、定着ローラ1の撓みに抗する方向に押圧部材11を付勢するスプリング等の付勢手段13,13を有している。押圧部材11は保持部材12に嵌合され、図の上下方向に移動可能に保持されており、付勢手段13,13によって定着ローラ1の撓みに抗する方向に付勢されている。撓み防止装置10は、定着ローラ1の軸方向の中央部において定着装置の構造部材8に取り付けられている。
【0024】
ここで、当然ながら、付勢手段13による(押圧部材11を介した)定着ローラ1への押圧力は、定着ローラ1の撓みを矯正可能な付勢力とする。この例においてはスプリング等の付勢手段13を設けているが、定着ローラ1の撓み量を矯正する位置に押圧部材の押圧部11a先端位置を予め合わせて固定した構成としても良い。
【0025】
図2に示すように、定着ローラ1の内面には特許文献3に開示されているような絞り加工によって形成した補強リブ9を複数設けてある。補強リブ9の本数は適宜仕様条件によって最適化されるべきであり、定着ローラ1の芯金肉厚、芯金材料、定着ローラ径、加圧力、ウォームアップ等の仕様を満足する条件において、適切な本数及び補強リブの断面形状を設定する。本例では定着ローラの通紙中央部(C領域)にリブ間隔10〜20mmで9本、ローラ端部(E領域)には20〜50mmの間隔で各々3本の補強リブ9を備えている。
【0026】
前述もしたが、補強リブ9は本数が多いほど定着ローラ1の撓み・潰れ剛性が高くなるが、その体積分、定着ローラの熱容量が増えるため、ウォームアップタイムは遅くなってしまう。そのため、ウォームアップ時間が狙いの時間となるように、ハロゲンヒータ7の出力と定着ローラ1の肉厚、補強リブ9の本数を設定する必要があり、この観点からは補強リブ9は少ない方が望ましく、前述のウォームアップ時間の短縮と定着ローラの機械的強度アップは相反する関係にある。
【0027】
一方、定着ローラ1の潰れは補強リブ9の効果によって改善可能であるのだが、前述の定着条件によっては万全とは言えない。特に大きな加圧力によって必要なニップ幅を得る必要のある高速機においては、撓み・潰れとも大きくなる傾向にあることは前述の図10のグラフからも判断できる。定着ローラ1の軸方向の撓みに関しては、図2に示すように、両端を定着ローラ軸受4によって支持された定着ローラ1の下面を加圧ローラ2によって押圧された場合、定着ローラ1の中央部が最大の撓み量となることは容易に想像できる。
【0028】
撓み防止装置10は定着ローラ1の軸方向中央部に設けることにより、より一層効果を得られるのだが、この際、前述の定着ローラ1中央部の内面に設けた補強リブ9と一致する位置に撓み防止装置10の押圧部11aが合致するように配置する。補強リブ9の位置と一致させる押圧部11aの個数は、定着ローラ中央部の一ヶ所であっても良いし、中央部数ヶ所に分散させても良い。本例では3箇所に分散させたものである。中央部一ヶ所にした場合は定着ローラ1と接触する箇所も一ヶ所になるため、定着ローラ1への押圧部11aによってローラを傷つけてしまった場合でも、損傷を最小限に抑えることができる。一方、一つの押圧部11aに荷重を集中させないために数ヶ所に分散させて設けても良い。定着ローラ1の潰れに関しては、潰れ強度が最も強いのは定着ローラ軸方向では補強リブ9が配置されている箇所である。補強リブ9が無い部分については近傍に補強リブ9が存在していても、潰れが発生し強度的には弱い箇所であるといえる。
【0029】
以上の観点から、定着ローラ1の補強リブ9位置に撓み防止装置10の押圧部11aを一致させることによって、定着ローラ内面に設けた補強リブ9による径方向の潰れ防止効果と合わせ、効果的に定着ローラ軸方向の撓み変形を抑止して定着ローラ1の変形によるニップ幅の減少による定着不良を防止する構成となっている。
【0030】
次に、定着装置の第2実施例について図3,4を参照して説明する。本実施例の定着装置は、図1,2で説明した前記実施例の定着装置とは、撓み防止装置20の構成が異なるのみであり、同一な部分については同じ符号を付すとともに、重複する説明を省略する。
【0031】
本実施例において、撓み防止装置20は、3つのコロ21、コロ21を支持するコロ軸22、軸受23、保持部材12、付勢手段13,13を有している。軸受23は保持部材12によって図の上下方向に移動可能に保持されており、付勢手段13,13によって図の下方に加圧され、3個のコロ21を定着ローラ1の撓みに抗する方向に付勢する。これによって、定着ローラ1の変形を制限している。なお、コロ21は定着ローラ1に連れ回りして回転する。
【0032】
ここで、当然ながら付勢手段13による(コロ21を介した)定着ローラ1への押圧力は、定着ローラ1の撓みを矯正可能な付勢力とする。この例においてはスプリング等の付勢手段13を設けているが、図6に示すように、定着ローラ1の撓み量を矯正する位置にコロ21先端位置を予め合わせて固定した構成としても良い。
【0033】
コロ21は金属製または耐熱性樹脂で形成され、表面(外周面)にはトナーの付着を防止するPAFやPTFE等の離型層を設けてもよい。
そして、コロ21の配置位置は、前記実施例における撓み防止装置10の押圧部11aと同様に、定着ローラ1中央部の内面に設けた補強リブ9と一致する位置にコロ21が合致するように配置する。また、コロ21の定着ローラとの接触部の形状は、先端が曲率を有する(図4の方向から見て)形状とし、トナーの付着を極力防止したものであることが望ましく、さらに接触箇所(コロ21の数)は本例では3箇所(3個)であるが、いたずらに接触箇所を増やすことにより定着ローラ1の熱を奪う恐れがあるので、図5に示すように1ヶ所(1個のコロ21)であっても良い。
【0034】
図6は、コロ軸受23をコロ保持部材24に固定した第3実施例であるが、この例でも同様の効果を得ることが可能であり、予め定着ローラ1の撓みの無い状態でコロ21と定着ローラ1が接触する位置にコロ21を配置するように、撓み防止装置20Cを構成してある。これによって、定着ローラ1の変形を制限している。
【0035】
図7に示す例では、撓み防止装置20Cのコロ21表面に接触するようにトナー除去部材25、例えばスクレーパを適当な圧力をかけて配置してある。コロ21へのトナー除去部材25の当接は図示しない付勢手段を用いても良いし、トナー除去部材25を固定配置し、トナー除去部材自体の弾性を利用しても良い。
【0036】
トナー除去部材25のコロとの接触部は鋭利な形状となっており、図中の矢印方向(時計回り)に定着ローラ1が回転した際、コロ21も同時に図中の矢印方向(反時計回り)に従動回転し、コロ21表面に付着したトナーをトナー除去部材25の先端部にて清掃できる構成となっている。
【0037】
トナー除去部材25の材質は、例えば厚さt=0.1mm程度のステンレス板であっても良いし、ポリイミドフィルムのような構成であっても良く、180℃前後で制御される定着ローラ1近傍に配置した際にも耐熱性を充分備えるものが好ましい。
【0038】
ところで、前述のようにコロ21は定着ローラ1に接触してこれを押圧しているため、画像形成動作時に定着ローラ1へ微少にオフセットしたトナーがコロ21へ転写されてしまう場合がある。コロ21自体の表面又は全体を離型性の優れるPFA、PTFE等の離型層を付加しても良いが、コロ21表面にトナーが付着した場合、コロ径の増大により適切な押圧力よりも強い荷重にて定着ローラ1を押圧してしまう恐れがある。また、コロ21の外周面に付着したトナーが定着ローラ表面に再転写されてしまった場合には、転写紙P上にトナーを転写して、異常画像となってしまう場合がある。そこで、本例では、トナー除去部材25をコロ21の外周面に当接させ、コロ外周面へのトナー付着を防止する構成となっている。また、トナー除去部材25のコロ回転方向の下流位置には、除去したトナーを堆積させるトナー回収部26を設けてあり、トナー除去部材25によって分離除去したトナーが定着ローラ1へ落下することによる画像異常を防止する構成となっている。図7の例ではコロ21の位置はコロ支持部材24に取りつけたコロ軸受23によって固定されているが(図6参照)、図3〜5の実施例のように付勢手段(13)によってコロ21を介して定着ローラ1を押圧する構成についても、トナー除去部材25及びトナー回収部26を設けることは、もちろん可能である。
【0039】
以上、本発明を図示例により説明したが、本発明はこれに限定されるものではない。定着ローラ内部に設けられたリブの本数や間隔あるいは形状は任意であり、絞り加工により形成したリブに限らず、補強リングを装填したものでも良い。また、そのリブ(補強部)あるいは補強リング(補強部材)の位置に合わせて設ける(ローラ軸方向の位置を一致させた)撓み規制部材の押圧部の個数も、図示例で示した1個あるいは3個に限らず、任意である。定着ローラの加熱方法も、ハロゲンヒータに限らず、誘導加熱、抵抗加熱等、任意の加熱方法を採用できる。また、加熱手段の配置場所も、ローラ内部に限らず、ローラ外部からの加熱でも良い。
【0040】
なお、定着装置以外の部分の画像形成装置の構成は、従来周知なものと同様であるので説明を省略する。また、画像形成装置としては、複写機、プリンタ、ファクシミリ、あるいは複合機等、任意な形態をとることができるものである。
【0041】
【発明の効果】
以上説明したように、本発明の定着装置及び画像形成装置によれば、撓み規制装置の押圧部材の定着ローラ軸方向の位置を定着ローラ内部に設けられた補強部材または補強部に一致させたので、定着ローラ内面に設けた補強部材または補強部による径方向の潰れ防止効果と合わせ、効果的に定着ローラ軸方向の撓み変形を抑止して定着ローラの変形によるニップ幅の減少を原因とする定着不良を防止することができる。また、少ない数の補強部材または補強部で定着ローラの変形(つぶれ、たわみ)を防止することができるので、コストダウンを図りつつ定着ローラの変形を防ぐことができる。
【0042】
請求項2の構成により、押圧部材が円筒形断面形状で回転可能に支持され、定着ローラに接触して回転するので、定着ローラ表面の損傷を防止することができる。
【0043】
請求項3の構成により、押圧部材の外周面に接触する清掃部材と、その清掃部材により清掃・回収した付着物を収容する付着物回収部とを設けたので、定着ローラから押圧部材に転移したトナー・紙粉等を清掃することができる。また、清掃・回収したトナー・紙粉等が定着ローラに再転写されることによって発生する異常画像を防止することができる。
【図面の簡単な説明】
【図1】本発明に係る定着装置の一例における要部を示す径方向の断面図である。
【図2】本発明に係る定着装置の一例における要部を示す軸方向の断面図である。
【図3】定着装置の第2実施例における要部を示す径方向の断面図である。
【図4】定着装置の第2実施例における要部を示す軸方向の断面図である。
【図5】1個のコロ(押圧部材)を有する撓み防止装置を備えた第2実施例の変形例を示す径方向の断面図である。
【図6】定着装置の第3実施例における要部を示す径方向の断面図である。
【図7】トナー除去部材及びトナー回収部を設けた第3実施例の変形例を示す径方向の断面図である。
【図8】従来の定着装置における定着ローラの軸方向の撓みを説明する模式図である。
【図9】従来の定着装置における定着ローラの径方向のつぶれを説明する模式図である。
【図10】加圧ローラによる荷重と定着ローラ変形量の関係を示すグラフである。
【符号の説明】
1 定着ローラ
2 加圧ローラ
9 補強リブ
10,20 撓み防止装置
11 押圧部材
11a 押圧部
12 保持部材
13 付勢手段
21 コロ(押圧部材)
25 トナー除去部材(清掃部材)
26 トナー回収部(付着物回収部)
[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fixing device in an image forming apparatus such as a copying machine, a printer, and a facsimile.
[0002]
[Prior art]
[Patent Document 1] JP-A-09-171321 [Patent Document 2] JP-A-09-212026 [Patent Document 3] JP-A-2002-106547 [Patent Document 4] JP-A-2001-296770 [0003] ]
In recent years, there has been a strong demand for energy saving in the field of image forming apparatuses, such as the recent increase in environmental improvement activities and the enactment of the Energy Conservation Law. Focusing on the inside of the image forming apparatus, the heat fixing device consumes a large amount of energy, and various technologies have been proposed and implemented for improving energy efficiency.
[0004]
As an example of improving energy efficiency, there is a method of lowering the standby temperature of the fixing roller when the image forming apparatus is not used, thereby improving energy consumption efficiency. However, according to this method, it takes a long time to warm up the fixing device during use, which causes a problem such that a user cannot immediately work.
[0005]
On the other hand, for example, by increasing the rate of increase in the temperature of the fixing roller (using a fixing roller having a large rate of temperature increase), the low temperature is maintained during standby, and the time required to reach the predetermined temperature during use = warm-up time. Can be shortened. As a method of shortening the warm-up time, it is only necessary to increase the temperature rise rate as described above. One of the methods is to use a member having a small heat capacity such as a thin metal pipe for the fixing roller core in recent years. Many are used.
[0006]
However, if the core of the fixing roller is unnecessarily thinned, the mechanical strength is reduced, and deformation problems such as bending in the longitudinal direction of the fixing roller and crushing of the fixing roller cross section occur. When such a deformation of the fixing roller occurs, the nip formed by the fixing roller and the pressure roller becomes narrow at the center in the axial direction, and a desired nip width cannot be obtained. Therefore, various problems such as generation of paper wrinkles due to a difference in linear velocity between the transport center portion and the end portion occur.
[0007]
That is, when the pressure roller 2 is pressed against the fixing roller 1 as shown in FIG. 8 when the pressure roller 2 is pressed against the fixing roller 1 as shown in FIG. d occurs, and at the same time, collapse of the radial cross section (crush amount = H1-H2) as shown in FIG. 9 is caused. This deformation has occurred to a considerable extent even in the conventional fixing device, but as described above, in the thin fixing roller for energy saving, as the amount of deformation, as a problem in image quality, Has become.
[0008]
The graph of FIG. 10 shows the measurement results of the displacement of the upper and lower surfaces of the fixing roller made of aluminum and the amount of crushing of the outer diameter in the pressing direction of the fixing roller made of aluminum and having a diameter of φ40 mm and a thickness t = 0.3 mm. As the load (pressing force) increases, the fixing roller bends in the axial direction, and the position of the lower surface (the amount of displacement of the lower surface in FIG. 10) increases, but the cross section in the radial direction is remarkably crushed. Conversely, the position of the upper surface of the fixing roller (the amount of displacement of the upper surface in FIG. 10) decreases with the load. Due to this deformation, as described above, the pressure is reduced at the center in the roller axis direction, and the nip is narrowed, so that a uniform nip cannot be formed.
[0009]
As a method for solving these problems, a structure in which a reinforcing member is provided outside or inside a fixing roller has been proposed, as disclosed in Patent Documents 1 and 2.
[0010]
The technique disclosed in Patent Literature 1 is intended to eliminate the deflection in the longitudinal direction of the fixing roller. The reinforcing roller is brought into contact with the pressure roller from the outside thereof, and a spring is applied in a direction to reduce the deflection. To reinforce the pressure roller. A technique of providing an auxiliary roller only at the center of the pressure roller is also disclosed.
[0011]
Further, the technique disclosed in Japanese Patent Application Laid-Open No. H11-133873 aims to eliminate collapse in the roller cross-sectional direction, and is configured by mounting a plurality of rings for reinforcement in a fixing roller.
[0012]
By mounting a ring for reinforcement inside the fixing roller, it is possible to greatly reduce the deflection and crushing of the cross section of the fixing roller.However, when a reinforcing member is mounted, some new problems arise. obtain.
[0013]
That is,
{Circle around (1)} It is difficult to fix the reinforcing member to the fixing roller.
{Circle around (2)} Since a large load is applied to the reinforcing member for preventing the deformation of the fixing roller, if the fixing member is not firmly fixed to the fixing roller, the reinforcing member will soon come off inside the fixing roller.
{Circle around (3)} When the reinforcing member is fixed in the fixing roller in a shrinking state, high accuracy is required for the reinforcing member, and the loading operation requires a technique.
{Circle around (4)} When the fixing roller is fixed in the fixing roller by welding or the like, not only the processing cost is increased, but also the load is concentrated on the welded portion, which may cause damage to the reinforcing ring.
{Circle around (5)} Since another member is contained inside the fixing roller, the heat capacity is locally increased, and the temperature rise in that portion is delayed.
{Circle around (6)} The configuration of the heat source of the fixing roller is restricted due to the reinforcing member (for example, when the fixing roller is heated by an internal halogen heater, the inner reinforcing member is heated before conducting heat to the core metal. And a delay in thermal response occurs).
And so on.
[0014]
[Problems to be solved by the invention]
To solve these problems, for example, Patent Document 3 discloses that a reinforcing rib for obtaining high rigidity of a fixing roller by drawing is provided on the inner surface of the fixing roller. According to this technique, it is effective against crushing in the circumferential direction, but there is a limit to bending in the axial direction, and especially when deployed in a high-speed machine, it is necessary to prevent bending under high load conditions. Is currently limited. Further, it is possible to prevent the bending and crushing by increasing the rib shape, the rib height, the number, and the like of the above-described ribs, but the heat capacity of the fixing roller increases and the effect of shortening the warm-up time decreases. In addition, as described in the above problem (5), there is a disadvantage that the heat capacity is locally increased and the temperature rise in that portion is slow.
[0015]
Further, the technique disclosed in Patent Document 4 is an example in which the above-described problem is solved by providing rollers for preventing bending in each of the bending direction and the crushing direction of the fixing roller. However, according to this technology, since the bending and crushing of the fixing roller is suppressed by a plurality of rollers, the temperature rise locally becomes slow at the contact portion due to the heat capacity of the roller, and the bending and crushing of the fixing roller are prevented. It is necessary to provide the rollers in the direction of suppressing them and to attach them to each of the strong structures, resulting in a problem that the cost is increased.
[0016]
The present invention solves the above-mentioned problems in the conventional fixing device and image forming apparatus, and can prevent deformation of the fixing roller at low cost, and can improve the fixing performance by making the nip with the pressure roller uniform. And an image forming apparatus.
[0017]
[Means for Solving the Problems]
According to the present invention, in a fixing device having a cylindrical fixing roller and a pressure roller pressed against the fixing roller, the fixing roller includes a reinforcing member for regulating deformation of the roller inside the roller. A deflection control device that has a reinforcing portion and has at least one pressing member that abuts on the outer peripheral surface of the fixing roller on the side opposite to the pressing roller, and that controls the deflection of the fixing roller due to the pressing of the pressing roller. And fixing the pressing member of the deflection control device in the axial direction of the fixing roller to the reinforcing member or the reinforcing portion inside the fixing roller.
[0018]
In order to solve the above-mentioned problems, the present invention proposes that the pressing member is rotatably supported in a cylindrical cross-sectional shape, and rotates in contact with the fixing roller.
Further, in order to solve the above-mentioned problem, the present invention proposes to provide a cleaning member that comes into contact with the outer peripheral surface of the pressing member, and an adhering matter collecting unit that stores the adhering matter cleaned and collected by the cleaning member. I do.
[0019]
According to the present invention, the above object is achieved by an image forming apparatus including the fixing device according to any one of claims 1 to 3.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are a sectional view in a radial direction and a sectional view in an axial direction showing a main part of an example of the fixing device according to the present invention.
[0021]
In these figures, the fixing roller 1 is rotatably supported on a fixing side plate 5 via a heat insulating bush 3 and a fixing roller bearing 4, and a gear 6 attached to one end of the fixing roller is not shown. It is adapted to receive a rotational driving force by meshing with a driving source. In this example, the material of the fixing roller 1 is a thin pipe of aluminum or iron as a base material, the thickness is about 0.3 to 2.0 mm, and a release layer such as a fluororesin is formed on the outer peripheral surface. , A halogen heater 7 is provided therein.
[0022]
Although not shown, a temperature sensor is arranged in contact with or close to the peripheral surface of the fixing roller 1, and energization to the halogen heater 7 is controlled based on the temperature of the fixing roller 1 detected by the temperature sensor. It has become. Normally, when the power of the image forming apparatus is turned on, a current flows to the halogen heater 7, and the temperature of the fixing roller 1 rapidly rises to a set temperature of about 180 ° C.
[0023]
A bending prevention device 10 is provided on the side opposite to the pressure roller 2 pressed against the fixing roller 1 so as to be in contact with the outer periphery of the fixing roller. The bending prevention device 10 has a pressing member 11 having a pressing portion 11 a that protrudes in a semicircular shape and is pressed against the fixing roller 1, a holding member 12 that holds the pressing member 11, and resists bending of the fixing roller 1. It has urging means 13 such as a spring for urging the pressing member 11 in the direction. The pressing member 11 is fitted to the holding member 12 and held so as to be movable in the vertical direction in the figure, and is urged by urging means 13 in a direction against the bending of the fixing roller 1. The bending prevention device 10 is attached to the structural member 8 of the fixing device at the axial center of the fixing roller 1.
[0024]
Here, naturally, the pressing force on the fixing roller 1 (via the pressing member 11) by the urging means 13 is an urging force capable of correcting the bending of the fixing roller 1. In this example, the urging means 13 such as a spring is provided, but a configuration may be employed in which the distal end position of the pressing portion 11a of the pressing member is previously adjusted to a position where the amount of bending of the fixing roller 1 is corrected.
[0025]
As shown in FIG. 2, a plurality of reinforcing ribs 9 formed by drawing as disclosed in Patent Document 3 are provided on the inner surface of the fixing roller 1. The number of the reinforcing ribs 9 should be appropriately optimized according to the specification conditions, and the number of the reinforcing ribs 9 should be optimized under the conditions satisfying the specifications such as the core metal wall thickness, the core metal material, the fixing roller diameter, the pressing force, and the warm-up. The number and the cross-sectional shape of the reinforcing rib are set. In the present embodiment, nine reinforcing ribs 9 are provided at the center portion (C region) of the fixing roller at a paper interval of 10 to 20 mm and three reinforcing ribs 9 are provided at an end portion of the roller (E region) at an interval of 20 to 50 mm. .
[0026]
As described above, as the number of the reinforcing ribs 9 increases, the flexure / crushing rigidity of the fixing roller 1 increases, but the warm-up time becomes slow because the volume and the heat capacity of the fixing roller increase. Therefore, it is necessary to set the output of the halogen heater 7, the thickness of the fixing roller 1, and the number of the reinforcing ribs 9 so that the warm-up time becomes a target time. Desirably, the shortening of the warm-up time and the increase in the mechanical strength of the fixing roller are in an opposite relationship.
[0027]
On the other hand, although the crushing of the fixing roller 1 can be improved by the effect of the reinforcing rib 9, it cannot be said that it is perfect depending on the fixing conditions described above. It can also be determined from the above-described graph of FIG. 10 that particularly in a high-speed machine in which a necessary nip width needs to be obtained by a large pressing force, both the bending and the crushing tend to increase. As shown in FIG. 2, when the lower surface of the fixing roller 1, whose both ends are supported by the fixing roller bearing 4, is pressed by the pressing roller 2, the central portion of the fixing roller 1 is deformed. Can be easily imagined to be the maximum amount of deflection.
[0028]
By providing the bending prevention device 10 at the central portion in the axial direction of the fixing roller 1, the effect can be further improved. In this case, the bending prevention device 10 is provided at a position corresponding to the reinforcing rib 9 provided on the inner surface of the central portion of the fixing roller 1. It is arranged so that the pressing portion 11a of the bending prevention device 10 matches. The number of the pressing portions 11a that match the positions of the reinforcing ribs 9 may be at one location in the center of the fixing roller, or may be dispersed at several locations in the center. In the present example, it is distributed at three places. In the case where the fixing roller 1 is located at one location, the location that comes into contact with the fixing roller 1 is also one location, so that even if the roller is damaged by the pressing portion 11a against the fixing roller 1, damage can be minimized. On the other hand, in order to prevent the load from being concentrated on one pressing portion 11a, the pressing portion 11a may be provided dispersedly at several places. Regarding the crushing of the fixing roller 1, the crushing strength is highest at the position where the reinforcing rib 9 is arranged in the fixing roller axial direction. It can be said that the portion where the reinforcing rib 9 is not present is a place where the reinforcing rib 9 is crushed and the strength is weak even if the reinforcing rib 9 is present in the vicinity.
[0029]
From the viewpoints described above, by matching the pressing portion 11a of the bending prevention device 10 with the reinforcing rib 9 of the fixing roller 1, the reinforcing rib 9 provided on the inner surface of the fixing roller can be effectively combined with the effect of preventing crushing in the radial direction. The configuration is such that bending deformation in the axial direction of the fixing roller is suppressed to prevent defective fixing due to a reduction in the nip width due to deformation of the fixing roller 1.
[0030]
Next, a second embodiment of the fixing device will be described with reference to FIGS. The fixing device according to the present embodiment is different from the fixing device according to the embodiment described with reference to FIGS. 1 and 2 only in the configuration of the deflection preventing device 20. Is omitted.
[0031]
In the present embodiment, the bending prevention device 20 includes three rollers 21, a roller shaft 22 that supports the rollers 21, a bearing 23, a holding member 12, and urging units 13. The bearing 23 is held by the holding member 12 so as to be movable in the up and down direction in the figure, and is pressed downward in the figure by the urging means 13, 13 so that the three rollers 21 resist the bending of the fixing roller 1. Energize to. This limits the deformation of the fixing roller 1. The roller 21 rotates with the fixing roller 1.
[0032]
Here, the pressing force on the fixing roller 1 (via the rollers 21) by the urging means 13 is, of course, an urging force capable of correcting the bending of the fixing roller 1. In this example, the urging means 13 such as a spring is provided. However, as shown in FIG. 6, a configuration may be employed in which the tip end position of the roller 21 is previously adjusted to a position where the amount of deflection of the fixing roller 1 is corrected.
[0033]
The roller 21 is made of a metal or a heat-resistant resin, and a release layer such as PAF or PTFE for preventing toner from adhering may be provided on the surface (outer peripheral surface).
The disposition position of the roller 21 is such that the roller 21 coincides with a position corresponding to the reinforcing rib 9 provided on the inner surface of the central portion of the fixing roller 1, similarly to the pressing portion 11 a of the bending prevention device 10 in the above embodiment. Deploy. Further, the shape of the contact portion of the roller 21 with the fixing roller is preferably such that the tip has a curvature (as viewed from the direction of FIG. 4) to prevent toner adhesion as much as possible. Although the number of the rollers 21 is three in this example (three), the heat of the fixing roller 1 may be deprived by increasing the number of contact points unnecessarily. Therefore, as shown in FIG. Roller 21).
[0034]
FIG. 6 shows a third embodiment in which the roller bearing 23 is fixed to the roller holding member 24. In this example, a similar effect can be obtained. The bending prevention device 20C is configured so that the roller 21 is arranged at a position where the fixing roller 1 contacts. This limits the deformation of the fixing roller 1.
[0035]
In the example shown in FIG. 7, a toner removing member 25, for example, a scraper is arranged by applying an appropriate pressure so as to contact the surface of the roller 21 of the deflection preventing device 20C. The contact of the toner removing member 25 with the roller 21 may be performed by using an urging means (not shown), or the toner removing member 25 may be fixedly arranged and the elasticity of the toner removing member itself may be used.
[0036]
The contact portion of the toner removing member 25 with the roller has a sharp shape, and when the fixing roller 1 rotates in the direction of the arrow (clockwise) in the figure, the roller 21 is simultaneously moved in the direction of the arrow (counterclockwise in the figure). ), The toner is adhered to the surface of the roller 21 and can be cleaned by the tip of the toner removing member 25.
[0037]
The material of the toner removing member 25 may be, for example, a stainless plate having a thickness t of about 0.1 mm or a structure such as a polyimide film, and the vicinity of the fixing roller 1 controlled at about 180 ° C. It is preferable that the material has sufficient heat resistance even when it is arranged in a space.
[0038]
By the way, since the roller 21 contacts and presses the fixing roller 1 as described above, the toner slightly offset to the fixing roller 1 may be transferred to the roller 21 during the image forming operation. A release layer such as PFA or PTFE having excellent releasability may be added to the surface or the entire surface of the roller 21 itself. There is a possibility that the fixing roller 1 will be pressed by a strong load. Further, when the toner adhered to the outer peripheral surface of the roller 21 is re-transferred to the surface of the fixing roller, the toner may be transferred onto the transfer paper P, resulting in an abnormal image. Therefore, in the present embodiment, the toner removing member 25 is configured to contact the outer peripheral surface of the roller 21 to prevent the toner from adhering to the outer peripheral surface of the roller 21. At the downstream position of the toner removing member 25 in the roller rotation direction, there is provided a toner collecting unit 26 for accumulating the removed toner, and the image formed by the toner separated and removed by the toner removing member 25 falling to the fixing roller 1 is provided. It is configured to prevent abnormalities. In the example of FIG. 7, the position of the roller 21 is fixed by a roller bearing 23 attached to a roller support member 24 (see FIG. 6). However, as in the embodiment of FIGS. It is of course possible to provide the toner removing member 25 and the toner collecting unit 26 with respect to the configuration in which the fixing roller 1 is pressed via the fixing roller 21.
[0039]
Although the present invention has been described with reference to the illustrated examples, the present invention is not limited thereto. The number, spacing, and shape of the ribs provided inside the fixing roller are arbitrary, and are not limited to ribs formed by drawing, but may be those provided with a reinforcing ring. In addition, the number of pressing portions of the deflection restricting member provided in accordance with the position of the rib (reinforcing portion) or the reinforcing ring (reinforcing member) (coordinated in the axial direction of the roller) is one or the same as shown in the illustrated example. The number is not limited to three. The heating method of the fixing roller is not limited to the halogen heater, and any heating method such as induction heating and resistance heating can be adopted. The location of the heating means is not limited to the inside of the roller, but may be heating from the outside of the roller.
[0040]
The configuration of the image forming apparatus other than the fixing device is the same as that of a conventionally known device, and a description thereof will be omitted. Further, the image forming apparatus can take any form such as a copying machine, a printer, a facsimile, or a multifunction peripheral.
[0041]
【The invention's effect】
As described above, according to the fixing device and the image forming apparatus of the present invention, the position of the pressing member of the deflection control device in the axial direction of the fixing roller matches the reinforcing member or the reinforcing portion provided inside the fixing roller. In addition to the effect of preventing the crushing in the radial direction by the reinforcing member or the reinforcing portion provided on the inner surface of the fixing roller, the fixing nip caused by the reduction of the nip width due to the deformation of the fixing roller by effectively suppressing the bending deformation in the fixing roller axial direction. Defects can be prevented. Further, since the deformation (crushing and bending) of the fixing roller can be prevented with a small number of reinforcing members or reinforcing portions, the deformation of the fixing roller can be prevented while reducing the cost.
[0042]
According to the configuration of the second aspect, the pressing member is rotatably supported in a cylindrical cross-sectional shape, and rotates in contact with the fixing roller, so that the surface of the fixing roller can be prevented from being damaged.
[0043]
According to the third aspect of the present invention, since the cleaning member that comes into contact with the outer peripheral surface of the pressing member and the deposit recovery section that stores the deposit cleaned and collected by the cleaning member are provided, the fixing roller is transferred to the pressing member. It can clean toner and paper dust. Further, it is possible to prevent an abnormal image caused by retransfer of the cleaned and collected toner and paper powder to the fixing roller.
[Brief description of the drawings]
FIG. 1 is a radial cross-sectional view showing a main part of an example of a fixing device according to the present invention.
FIG. 2 is an axial sectional view showing a main part of an example of the fixing device according to the present invention.
FIG. 3 is a radial cross-sectional view illustrating a main part of a second embodiment of the fixing device.
FIG. 4 is an axial sectional view showing a main part of a second embodiment of the fixing device.
FIG. 5 is a radial cross-sectional view showing a modification of the second embodiment provided with a deflection preventing device having one roller (pressing member).
FIG. 6 is a radial sectional view showing a main part of a third embodiment of the fixing device.
FIG. 7 is a radial cross-sectional view showing a modification of the third embodiment in which a toner removing member and a toner collecting section are provided.
FIG. 8 is a schematic diagram for explaining an axial deflection of a fixing roller in a conventional fixing device.
FIG. 9 is a schematic diagram for explaining radial collapse of a fixing roller in a conventional fixing device.
FIG. 10 is a graph showing a relationship between a load due to a pressure roller and a deformation amount of a fixing roller.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 9 Reinforcement rib 10, 20 Bending prevention device 11 Pressing member 11a Pressing portion 12 Holding member 13 Energizing means 21 Roller (pressing member)
25 Toner removal member (cleaning member)
26 Toner Collection Section (Adhesion Collection Section)

Claims (4)

円筒状の定着ローラと該定着ローラに圧接される加圧ローラとを有する定着装置において、
前記定着ローラはローラ内部にローラの変形を規制するための補強部材または補強部を有し、
前記加圧ローラと反対側で前記定着ローラ外周面に当接する少なくとも1つの押圧部材を有して、前記加圧ローラの圧接による前記定着ローラの撓みを規制する撓み規制装置を設け、
前記撓み規制装置の押圧部材の前記定着ローラ軸方向の位置を、定着ローラ内部の前記補強部材または補強部に一致させたことを特徴とする定着装置。
In a fixing device having a cylindrical fixing roller and a pressure roller pressed against the fixing roller,
The fixing roller has a reinforcing member or a reinforcing portion for regulating deformation of the roller inside the roller,
A deflection regulating device that has at least one pressing member that abuts on the outer peripheral surface of the fixing roller on the side opposite to the pressure roller, and that regulates deflection of the fixing roller due to pressure contact of the pressure roller;
A fixing device, wherein a position of a pressing member of the deflection control device in an axial direction of the fixing roller coincides with the reinforcing member or the reinforcing portion inside the fixing roller.
前記押圧部材が円筒形断面形状で回転可能に支持され、前記定着ローラに接触して回転することを特徴とする、請求項1に記載の定着装置。The fixing device according to claim 1, wherein the pressing member is rotatably supported in a cylindrical cross-sectional shape, and rotates in contact with the fixing roller. 前記押圧部材の外周面に接触する清掃部材と、該清掃部材により清掃・回収した付着物を収容する付着物回収部とを設けたことを特徴とする、請求項2に記載の定着装置。The fixing device according to claim 2, further comprising: a cleaning member that contacts an outer peripheral surface of the pressing member; and an adhering matter collecting unit that stores the adhering matter cleaned and collected by the cleaning member. 請求項1〜3のいずれか1項に記載の定着装置を備えることを特徴とする画像形成装置。An image forming apparatus comprising the fixing device according to claim 1.
JP2003045861A 2003-02-24 2003-02-24 Fixing apparatus and image forming apparatus Expired - Fee Related JP4110010B2 (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008268343A (en) * 2007-04-17 2008-11-06 Murata Mach Ltd Fixing device
JP2010080351A (en) * 2008-09-27 2010-04-08 Ushio Inc Excimer lamp apparatus
JP2010210912A (en) * 2009-03-10 2010-09-24 Fuji Xerox Co Ltd Fixing device and image forming apparatus
JP2011248143A (en) * 2010-05-27 2011-12-08 Brother Ind Ltd Fixing device
US8755704B2 (en) 2010-05-27 2014-06-17 Brother Kogyo Kabushiki Kaisha Fixing device having heat roller reinforced by coil

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008268343A (en) * 2007-04-17 2008-11-06 Murata Mach Ltd Fixing device
JP2010080351A (en) * 2008-09-27 2010-04-08 Ushio Inc Excimer lamp apparatus
JP2010210912A (en) * 2009-03-10 2010-09-24 Fuji Xerox Co Ltd Fixing device and image forming apparatus
JP2011248143A (en) * 2010-05-27 2011-12-08 Brother Ind Ltd Fixing device
US8755704B2 (en) 2010-05-27 2014-06-17 Brother Kogyo Kabushiki Kaisha Fixing device having heat roller reinforced by coil

Also Published As

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