JP2009175458A - Image forming apparatus - Google Patents

Image forming apparatus Download PDF

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JP2009175458A
JP2009175458A JP2008014324A JP2008014324A JP2009175458A JP 2009175458 A JP2009175458 A JP 2009175458A JP 2008014324 A JP2008014324 A JP 2008014324A JP 2008014324 A JP2008014324 A JP 2008014324A JP 2009175458 A JP2009175458 A JP 2009175458A
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recording material
image recording
fixing
roller
fixing device
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JP5223355B2 (en
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Yasushi Hashimoto
靖司 橋本
Tomoshige Kurohane
基滋 黒羽根
Masami Takeshita
雅美 竹下
Kazuhiko Kawasaki
川崎  和彦
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Ricoh Co Ltd
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Ricoh Co Ltd
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  • Paper Feeding For Electrophotography (AREA)
  • Feeding Of Articles By Means Other Than Belts Or Rollers (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, preventing fixing creases and turbulence of an image even in the case of printing using a thin and large-sized paper sheet. <P>SOLUTION: The downstream side ridge line of a guide surface of a fixing device introducing guide member is formed in such a curve that the central part is recessed to the upstream side from both end parts of the ridge line to have the following positional relationship. The most downstream end in the direction of carrying an image recording material of a guide surface of the fixing device introducing guide member is located at the heat roller side with respect to the nip plane, and the leading end of the image recording material guided by the fixing device introducing guide member comes into contact with the heat roller earlier. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、プリンタや複写機等に代表される画像形成装置に係り、特に感光体上に現像されたトナー像を画像記録材に転写するための転写装置と、前記画像記録材上に転写されたトナーを加熱加圧することで画像記録材に定着させるための定着装置を備えた画像形成装置に関するものである。   The present invention relates to an image forming apparatus typified by a printer, a copying machine, and the like, and in particular, a transfer device for transferring a toner image developed on a photosensitive member to an image recording material, and the image forming material transferred onto the image recording material. The present invention relates to an image forming apparatus including a fixing device for fixing the toner onto the image recording material by heating and pressing.

従来、画像記録材上に形成されたトナー像を加熱定着する定着装置においては、熱ローラ方式が一般的である。図6に、従来の電子写真式画像形成装置の定着装置及び定着装置周辺の画像記録材搬送機構の構造を簡略的に示す。   Conventionally, a heat roller method is generally used in a fixing device that heats and fixes a toner image formed on an image recording material. FIG. 6 schematically shows the structure of a fixing device of a conventional electrophotographic image forming apparatus and an image recording material transport mechanism around the fixing device.

加熱ローラ9aの内部には、ハロゲンランプ等の加熱手段(図示せず)が備えられている。通常加熱ローラ9aは、円筒状の芯金の表面にトナーの離形性を向上するためのフッ素樹脂またはシリコンゴムをコーティングしたものである。フッ素系樹脂層はPFA樹脂のチュービングで形成してもよく、PFA樹脂を焼き付けてもよい。加圧ローラ9bは芯金の表面に耐熱性の高いシリコンゴムを弾性体層として設け、表面に離形性の良いPFAをチュービングしたものが主流である。   Heating means (not shown) such as a halogen lamp is provided inside the heating roller 9a. Usually, the heating roller 9a is formed by coating the surface of a cylindrical cored bar with a fluororesin or silicon rubber for improving toner releasability. The fluorine-based resin layer may be formed by tubing of PFA resin, or PFA resin may be baked. As the pressure roller 9b, the mainstream is one in which a silicon rubber having a high heat resistance is provided as an elastic layer on the surface of the core metal and a PFA having a good releasability is tubing on the surface.

前記加熱ローラと加圧ローラで構成する定着ローラ対は、ばね力を用いた加圧手段(図示せず)により、互いに押し付けられ、加圧ローラ9aの弾性体層の変形により面的に接触する。この接触面をニップ部と言う。前記加熱ローラ9aと加圧ローラ9bは前記ニップ部を形成した状態で定着ローラ対駆動手段とローラ駆動制御手段によって1方向に回転駆動される。   The pair of fixing rollers constituted by the heating roller and the pressure roller are pressed against each other by a pressing means (not shown) using a spring force, and are brought into surface contact by deformation of the elastic body layer of the pressure roller 9a. . This contact surface is called a nip portion. The heating roller 9a and the pressure roller 9b are rotationally driven in one direction by a fixing roller pair driving unit and a roller driving control unit in a state where the nip portion is formed.

周知の電子写真プロセスにより感光ドラム6上に可視化されたトナー像は転写器8により画像記録材である用紙22に転写され、送紙路12上を加熱ローラ9aと加圧ローラ9bからなる前記ニップ部へと運ばれる。定着装置導入ガイド部材16は用紙22を前記ニップ部へと案内する作用を果たし、その下流端は直線の同一面に成形されている。この一連のプロセスにより、用紙22上に形成されたトナー像は加熱ローラ9aと加圧ローラ9bにより加熱と同時に加圧を受け用紙22に定着される。   The toner image visualized on the photosensitive drum 6 by a known electrophotographic process is transferred to the paper 22 as an image recording material by the transfer device 8, and the nip comprising the heating roller 9 a and the pressure roller 9 b on the paper feeding path 12. Carried to the department. The fixing device introduction guide member 16 serves to guide the paper 22 to the nip portion, and its downstream end is formed on the same straight line. Through this series of processes, the toner image formed on the paper 22 is heated and pressurized simultaneously by the heating roller 9a and the pressure roller 9b and fixed on the paper 22.

前述の熱ローラ方式の定着装置では、含水率が高く薄い画像記録材を使用した場合に、ニップ部で画像記録材が急激に加熱されることで水分が蒸発し画像記録材が熱収縮し画像記録材にひずみを発生させ、このひずみがしわに発展することがある。このため、加熱ローラの外形を中央部が細く端部が太い、所謂アンダークラウン形状にすることで、画像記録材端部での加圧ローラのひずみを大きくしニップ部分では画像記録材を端部方向に押し広げる作用を与えてしわを防止する方法が一般的になっている。   In the above-described heat roller type fixing device, when a thin image recording material having a high water content is used, the image recording material is rapidly heated at the nip portion, whereby moisture is evaporated and the image recording material is thermally contracted. A distortion may be generated in the recording material, and this distortion may develop into wrinkles. For this reason, the outer shape of the heating roller has a thin center portion and a thick end portion, so-called under crown shape, which increases the distortion of the pressure roller at the end portion of the image recording material and causes the end portion of the image recording material at the nip portion. A method of preventing wrinkles by applying an action of spreading in the direction is becoming common.

また、特許文献1では、画像記録材をニップ部に案内するガイド部材の幅方向を中高とし、中央部を加熱ローラに近づけることで画像記録材の両側部分が中央付近に寄ることを防止し、且つ画像記録材を加熱ローラに当接してからニップ部に送り込むことで、画像記録材が前記ガイド部材と加熱ローラとにより短い距離で湾曲させられ、その先端部分が剛性を有することになり、平面性を保つことでしわを抑止する技術が提案されている。   Further, in Patent Document 1, the width direction of the guide member that guides the image recording material to the nip portion is set to the middle height, and the central portion is brought close to the heating roller to prevent the both side portions of the image recording material from being near the center, Further, the image recording material is brought into contact with the heating roller and then fed into the nip portion, whereby the image recording material is bent at a short distance by the guide member and the heating roller, and the leading end portion has rigidity, and is flat. Techniques have been proposed to suppress wrinkles by maintaining the nature.

また、特許文献2では、前記ガイド部材の下流側端部の高さ方向の形状を加熱ローラと加圧ローラのニップ部の入り口の形状と一致させること、即ち前記ガイド部材の下流側端部をアンダークラウン形状に合わせた中高にすることでの出画像記録材のニップ部への食い込みを均一にすることによるしわ抑止技術が提案されている。   Further, in Patent Document 2, the shape of the downstream end portion of the guide member in the height direction is matched with the shape of the entrance of the nip portion of the heating roller and the pressure roller, that is, the downstream end portion of the guide member is There has been proposed a wrinkle suppression technique by making the output image recording material bite into the nip portion evenly by setting the height to match the under crown shape.

一方、特許文献3では、ヒータを内蔵した耐熱エンドレスフィルムとシリコンゴム等よりなる弾性体層を持つ加圧ロールを用いたフィルム加熱定着装置の定着機入り口ガイドのニップ部に近接する側の両端の高い部分と中央部の低い部分の2平面で構成することが提案されている。上記文献では、ニップ部に案内される画像記録材を凹形状にすることで、画像記録材はその端部からニップ部に突入するため、端部から押し広げられることで中央部の用紙重なりによるしわを防止する効果が説明されている。ここで提案されている技術では画像記録材の端部を高くしてニップ部に導入した時に端部が先にニップ部に突入することから、幾何学的に考察して前記定着入り口ガイドの下流端はニップ平面に対して下方に位置していることが前提となる。この構成は、特許文献1では画像記録材をニップ部に案内するガイド部材の幅方向を中高とする構成を上下逆転させた構成であり同技術の延長線上にあるしわ防止技術の開示である。   On the other hand, in Patent Document 3, both ends on the side close to the nip portion of the fixing machine entrance guide of a film heating and fixing apparatus using a heat-resistant endless film with a built-in heater and a pressure roll having an elastic layer made of silicon rubber or the like are used. It has been proposed to be composed of two planes, a high portion and a low portion at the center. In the above document, since the image recording material guided to the nip portion is formed in a concave shape, the image recording material enters the nip portion from the end portion thereof, and is spread from the end portion, thereby causing a sheet overlap in the central portion. The effect of preventing wrinkles is described. In the technique proposed here, when the edge of the image recording material is raised and introduced into the nip portion, the edge portion first enters the nip portion. It is assumed that the end is located below the nip plane. This configuration is a configuration in which the configuration in which the width direction of the guide member that guides the image recording material to the nip portion is turned upside down in Patent Document 1 is a disclosure of a wrinkle prevention technique on the extension line of the same technology.

前述したそれぞれの技術は、ニップ部に突入する画像記録材の先端の姿勢を最適化することでしわの発生頻度を防止できると説明されているが、画像記録材にカットシートを用いる電子写真式の画像形成装置では、定着装置に搬送される画像記録材は殆どの場合斜行(所謂スキュー)して搬送されるため、前述した技術を用いた場合にもニップ部に突入する画像記録材の先端は必ずしも意図した通りには食い込まれない。ニップ部での画像記録材のスキューのしわ発生頻度への影響度合いは大きく、前述した技術だけではしわの発生は完全に防止することはできない。しわの防止には定着ローラに十分なアンダークラウン形状を持たせることが必要である。しかしながら、定着ローラのアンダークラウンが大きすぎる場合には、ニップ部での画像記録材を端部方向に押し広げる作用により画像記録材の下流側が歪むことで、画像記録材の表面に画像記録材の平面に垂直方向に変形した波打ちが発生することがある。波打った画像記録材がニップ部に食い込まれる時に定着ローラとの接触によるぶれにより画像記録材上に転写されたトナー像が乱れ、画像乱れが発生する。   Each of the technologies described above is described as being able to prevent the occurrence of wrinkles by optimizing the attitude of the tip of the image recording material that enters the nip portion. However, the electrophotographic method uses a cut sheet for the image recording material. In this image forming apparatus, since the image recording material conveyed to the fixing device is conveyed in a skewed manner (so-called skew) in most cases, the image recording material that enters the nip portion even when the above-described technique is used. The tip does not always bite as intended. The degree of influence of the skew of the image recording material on the nip portion on the frequency of occurrence of wrinkles is large, and the generation of wrinkles cannot be completely prevented only by the technique described above. In order to prevent wrinkles, it is necessary that the fixing roller has a sufficient under crown shape. However, when the under crown of the fixing roller is too large, the downstream side of the image recording material is distorted by the action of spreading the image recording material at the nip portion in the direction of the end portion, so that the image recording material on the surface of the image recording material. Waves deformed in a direction perpendicular to the plane may occur. When the wavy image recording material bites into the nip portion, the toner image transferred onto the image recording material is disturbed due to shaking due to contact with the fixing roller, and image disturbance occurs.

当業者では長年に亘る経験で、加熱ロールのアンダークラウンを径寸法200μm程度とし、ニップ部が先細り(端部が細くなる状態)のない状態で、搬送方向幅を10mm以上(所謂先細り)に設定すれば、定着入り口ガイドのニップ部に近接した稜線は同一高さの直線であっても、ニップ平面よりも加熱ローラの近い側にすれば画像記録材の搬送状態に多少のスキューがある場合にも、殆どの場合しわを防止できている。また、前記構成であれば、A3サイズやレジャーサイズのような幅が広く、長い用紙であっても加熱ローラのアンダークラウンによる画像乱れの発生も防止できている。   A person skilled in the art has many years of experience, setting the under crown of the heating roll to a diameter of about 200 μm, and setting the width in the transport direction to 10 mm or more (so-called taper) without the nip portion being tapered (the end portion being narrowed). In this case, even if the ridge line near the nip portion of the fixing entrance guide is a straight line having the same height, if there is a slight skew in the conveyance state of the image recording material if it is closer to the heating roller than the nip plane. However, in most cases, wrinkles can be prevented. In addition, with the above configuration, it is possible to prevent the occurrence of image disturbance due to the under crown of the heating roller even with a wide paper such as A3 size or leisure size and long paper.

近年Print On Demandのニーズにより、電子写真式画像形成装置の扱う画像記録材はDM(ダイレクトメール)市場では厚紙のコート紙やプレプリント紙を多く使用する傾向にあるが、一方では出版業界市場のBook On Demandのニーズによりサイズが大きく且つ軽量の画像記録材を使用する要求も高まっている。例えば、日本国内ではA5サイズで製本する場合、坪量60g/m程度の薄紙のA3サイズより大きな伸びサイズを使用して、A5サイズ4面分のデータを両面印刷し、同時に8頁分の印刷をする用途に使用する事例がある。海外では、製品の取扱マニュアル等を製本するため、坪量75g/mの用紙で14インチ(355.6mm)×18インチ(457.2mm)以上のサイズに4面分のデータを両面印刷する事例がある。このような薄紙で且つ大判用紙を使用した印刷の場合には、画像記録材の腰が弱いこととニップ部の歪みのしわ寄せが大きくなることで、前述のアンダークラウンによる画像乱れが顕著に現れ易くなる。この現象は前述のアンダークラウン量を小さくすることで軽減できるが、一方でしわに対するマージンは減少する。 In recent years, due to the needs of Print On Demand, image recording materials handled by electrophotographic image forming apparatuses tend to use a lot of cardboard coated paper and preprinted paper in the DM (direct mail) market. Due to the needs of Book On Demand, there is an increasing demand for using a large and lightweight image recording material. For example, when binding in A5 size in Japan, using a stretch size larger than the A3 size of thin paper with a basis weight of about 60 g / m 2 , double-sided printing of data for four A5 sizes, and simultaneously for eight pages There are cases where it is used for printing purposes. Overseas, in order to bind product handling manuals, etc., double-sided printing of 4 pages of data on a 14-inch (355.6 mm) x 18-inch (457.2 mm) or larger size paper with a basis weight of 75 g / m 2 There is a case. In the case of printing using such thin paper and large format paper, the image distortion due to the above-mentioned under crown is likely to appear remarkably due to the weakness of the image recording material and the wrinkle of distortion of the nip portion. Become. This phenomenon can be mitigated by reducing the amount of undercrown described above, but the margin for wrinkles is reduced.

実開昭56−130954号公報Japanese Utility Model Publication No. 56-130954 特開平6−95542号公報JP-A-6-95542 特開2006−91448号公報JP 2006-91448 A

本発明における第1の目的は、上記従来技術の欠点を解消し、薄紙で且つ大判用紙を使用した印刷の場合にも、定着しわや画像乱れのない画像形成装置を提供することにある。   A first object of the present invention is to provide an image forming apparatus that eliminates the above-mentioned drawbacks of the prior art and is free from fixing wrinkles and image distortion even in printing using thin paper and large format paper.

また、本発明における第2の目的は、定着しわや画像乱れのない画像形成装置を安価な構成で提供することにある。   A second object of the present invention is to provide an image forming apparatus free from fixing wrinkles and image distortion with an inexpensive configuration.

また、本発明における第3の目的は、画像乱れ及び定着しわに対する裕度をさらに向上させた画像形成装置を提供することにある。   A third object of the present invention is to provide an image forming apparatus that further improves the tolerance to image distortion and fixing wrinkles.

上記課題を解決するために、感光体上に現像されたトナー像を画像記録材に転写するための転写装置と前記画像記録材上に転写されたトナーを加熱加圧することで画像記録材に定着させるための定着装置をつなぐ搬送経路上に、前記定着装置を構成する加熱ローラと加圧ローラのニップ部に前記画像記録材を案内する定着装置導入ガイド部材を前記加熱ローラと加圧ローラの直上流の加圧ローラ側、即ち画像記録材の未定着トナーが転写されていない面が接触する側に設け、前記定着装置導入ガイド部材のガイド面の画像記録材搬送方向の最下流端が前記加熱ローラと前記加圧ローラの中心を結ぶ直線に直行する加熱ローラと前記加圧ローラのニップ点を含むニップ平面に対して加熱ローラ側に位置するように構成し、前記定着装置導入ガイド部材により案内される画像記録材先端が先に前記加熱ローラに接触する位置関係をなし、前記定着装置導入ガイド部材のガイド面の下流側の稜線を中央部が該稜線の両端部よりも上流側に凹になる曲線で構成していることを特徴とする。   In order to solve the above problems, a transfer device for transferring a toner image developed on a photoreceptor to an image recording material, and fixing the toner image transferred on the image recording material by heating and pressing the toner image. A fixing device introduction guide member for guiding the image recording material to a nip portion of the heating roller and the pressure roller constituting the fixing device on a conveyance path connecting the fixing device for causing the fixing device to directly connect the heating roller and the pressure roller. Provided on the upstream pressure roller side, that is, the side where the unfixed toner is not transferred on the image recording material, and the most downstream end of the guide surface of the fixing device introduction guide member in the image recording material conveyance direction is the heating A fixing roller introduction guide configured to be positioned on the heating roller side with respect to a nip plane including a nip point of the pressure roller and a heating roller that is perpendicular to a straight line connecting the roller and the center of the pressure roller; The leading edge of the image recording material guided by the member has a positional relationship with which the heating roller comes into contact first, and the ridge line on the downstream side of the guide surface of the fixing device introduction guide member has a central portion upstream of both end portions of the ridge line. It is characterized by comprising a concave curve.

また、給紙トレイと給紙トレイにセットされた画像記録材のサイズを検出する検出手段または、オペレータが画像記録材サイズを入力する入力手段あるいは前記検出手段と前記入力手段の両方と前記検出手段または入力手段で入力した画像記録材サイズ情報を記録するための書換え可能なメモリー手段と感光体上に現像されたトナー像を画像記録材に転写するための転写装置と前記画像記録材上に転写されたトナーを加熱加圧することで画像記録材に定着させるための定着装置を具備する電子写真式画像形成装置において、前記定着装置を加熱ローラと前記加熱ローラに押圧されてニップを形成する加圧ローラの定着ローラ対で構成し、前記定着ローラ対を回転駆動する駆動手段と前記定着ローラ対のニップ部の線速度を前記感光体の線速度と概略同速度に前記回転駆動手段の回転数を制御するための制御手段を具備し、使用する画像記録材サイズの幅または長さが予め設定した画像記録材サイズを超えた場合には前記定着ローラ対のニップ部の線速度を前記感光体の線速度よりも遅い第二の速度に前記駆動手段の回転数を制御することを特徴とする。   Also, a detection means for detecting the size of the image recording material set on the paper feed tray and the paper feed tray, an input means for inputting an image recording material size by an operator, or both of the detection means and the input means, and the detection means Alternatively, rewritable memory means for recording image recording material size information input by the input means, a transfer device for transferring the toner image developed on the photoreceptor to the image recording material, and transfer onto the image recording material In an electrophotographic image forming apparatus having a fixing device for fixing the toner on the image recording material by heating and pressing, the fixing device is pressed by the heating roller and the heating roller to form a nip. It is composed of a pair of fixing rollers of a pressure roller, and a linear velocity of a driving means for rotationally driving the fixing roller pair and a nip portion of the fixing roller pair is defined as a linear velocity of the photosensitive member Control means for controlling the rotational speed of the rotational drive means at substantially the same speed, and when the width or length of the image recording material size used exceeds a preset image recording material size, the fixing roller The rotational speed of the driving means is controlled to a second speed that is lower than the linear speed of the photosensitive member.

また、給紙トレイと給紙トレイにセットされた画像記録材のサイズを検出する検出手段または、オペレータが画像記録材サイズを入力する入力手段あるいは前記検出手段と前記入力手段の両方と前記検出手段または入力手段で入力した画像記録材サイズ情報を記録するための書換え可能なメモリー手段と印刷開始後の印刷枚数を計数する計数手段と感光体上に現像されたトナー像を画像記録材に転写するための転写装置と前記画像記録材上に転写されたトナーを加熱加圧することで画像記録材に定着させるための定着装置を具備する電子写真式画像形成装置において、前記定着装置を加熱ローラと前記加熱ローラに押圧されてニップを形成する加圧ローラの定着ローラ対で構成し、前記定着ローラ対を回転駆動する駆動手段と前記定着ローラ対のニップ部の線速度を前記感光体の線速度(以下プロセス速度と称する)と概略同速度に前記回転駆動手段の回転数を制御するための制御手段を具備し、印刷開始時には前記プロセス速度で前記駆動手段の回転数を制御し、予め設定した枚数の画像記録材を印刷した後、画像記録材サイズの幅または長さが予め設定した画像記録材サイズを超えている場合には前記加熱ローラと加圧ローラのニップ部の線速度を前記プロセス速度よりも遅い第二の速度に前記駆動手段の回転数を制御することを特徴とする。   Also, a detection means for detecting the size of the image recording material set on the paper feed tray and the paper feed tray, an input means for inputting an image recording material size by an operator, or both of the detection means and the input means, and the detection means Alternatively, rewritable memory means for recording image recording material size information input by the input means, counting means for counting the number of printed sheets after printing, and a toner image developed on the photosensitive member are transferred to the image recording material. An electrophotographic image forming apparatus comprising a transfer device for fixing the toner transferred onto the image recording material by heating and pressurizing the image recording material, and the fixing device includes a heating roller and the fixing device. The fixing roller pair of a pressure roller that is pressed by a heating roller to form a nip, and driving means for rotationally driving the fixing roller pair and the fixing roller And a control means for controlling the rotational speed of the rotation driving means so that the linear speed of the nip portion is substantially the same as the linear speed of the photosensitive member (hereinafter referred to as process speed). After controlling the number of rotations of the driving means and printing a predetermined number of image recording materials, if the width or length of the image recording material size exceeds the preset image recording material size, the heating roller And the rotational speed of the driving means is controlled to a second speed that is lower than the process speed.

また、給紙トレイと給紙トレイにセットされた画像記録材のサイズを検出する検出手段または、オペレータが画像記録材サイズを入力する入力手段あるいは前記検出手段と前記入力手段の両方と前記検出手段または入力手段で入力した画像記録材サイズ情報を記録するための書換え可能なメモリー手段と印刷開始後の印刷枚数を計数する計数手段と感光体上に現像されたトナー像を画像記録材に転写するための転写装置と前記画像記録材上に転写されたトナーを加熱加圧することで画像記録材に定着させるための定着装置を具備する電子写真式画像形成装置において、前記定着装置を加熱ローラと前記加熱ローラに押圧されてニップを形成する加圧ローラの定着ローラ対で構成し、前記定着ローラ対を回転駆動する駆動手段と前記定着ローラ対のニップ部の線速度を前記感光体の線速度と概略同速度に前記回転駆動手段の回転数を制御するための制御手段を具備し、印刷開始時には前記感光体の線速度で前記駆動手段の回転数を制御し、予め設定した枚数の画像記録材を印刷した後、画像記録材サイズの幅または長さが予め設定した画像記録材サイズを超えている場合には前記加熱ローラと加圧ローラのニップ部の線速度を前記感光体の線速度よりも遅い第二の速度に前記駆動手段の回転数を制御することを特徴とする。   Also, a detection means for detecting the size of the image recording material set on the paper feed tray and the paper feed tray, an input means for inputting an image recording material size by an operator, or both of the detection means and the input means, and the detection means Alternatively, rewritable memory means for recording image recording material size information input by the input means, counting means for counting the number of printed sheets after printing, and a toner image developed on the photosensitive member are transferred to the image recording material. An electrophotographic image forming apparatus comprising a transfer device for fixing the toner transferred onto the image recording material by heating and pressurizing the image recording material, and the fixing device includes a heating roller and the fixing device. The fixing roller pair of a pressure roller that is pressed by a heating roller to form a nip, and driving means for rotationally driving the fixing roller pair and the fixing roller Control means for controlling the rotational speed of the rotation driving means so that the linear velocity of the nip portion is approximately the same as the linear velocity of the photosensitive member, and at the start of printing, at the linear velocity of the photosensitive member, After controlling the number of rotations and printing a predetermined number of image recording materials, when the width or length of the image recording material size exceeds the preset image recording material size, the heating roller and the pressure roller The rotational speed of the driving means is controlled to a second speed that is lower than the linear speed of the photosensitive member.

本発明によれば、薄紙で且つ大判用紙を使用した印刷の場合にも、定着しわや画像乱れのない画像形成装置を提供することができる。また、上記画像形成装置を安価な構成で提供できる。更に、画像乱れ及び定着しわに対する裕度を向上することができる。   According to the present invention, it is possible to provide an image forming apparatus that is free from fixing wrinkles and image distortion even in the case of printing using thin paper and large format paper. In addition, the image forming apparatus can be provided with an inexpensive configuration. Furthermore, the tolerance for image disturbance and fixing wrinkles can be improved.

以下、本発明の一実施例を、図面を用いて説明する。図2は画像形成装置システムの全体構成図である。図2に示すように、画像形成装置システムは、画像形成装置1および用紙取扱装置2によって構成される。本実施例において、画像形成装置1としては、感光体を用い、周知の電子写真プロセスにより画像記録材上にトナー像を記録形成するレーザプリンタである。また、用紙取扱装置2としては、プリンタ1から排出された用紙をトレイ上に積み重ねて保持するスタッカである。   Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is an overall configuration diagram of the image forming apparatus system. As shown in FIG. 2, the image forming apparatus system includes an image forming apparatus 1 and a paper handling apparatus 2. In this embodiment, the image forming apparatus 1 is a laser printer that uses a photoreceptor and records and forms a toner image on an image recording material by a known electrophotographic process. The paper handling device 2 is a stacker that stacks and holds the paper discharged from the printer 1 on a tray.

プリンタ1において、3,4,5は画像記録材収容部であり、画像記録材としての用紙を収容している。6は感光ドラムで、コントローラ(図示せず)からの信号に基づいて矢印の方向へ回転を始める。感光ドラム6が回転を開始すると、コロナ帯電器(図示せず)によって感光ドラム6表面は均一に帯電される。帯電した感光ドラム6には露光装置(図示せず)から出射されたレーザビームによって静電潜像が形成される。静電潜像は現像装置7の位置に到達するとトナーによって現像され、感光ドラム6上にトナー像として可視化される。こうして周知の電子写真プロセスにより形成されたトナー像は転写器8により画像記録材収容部3,4,5または後述する戻し路14から送り出されてきた用紙に転写される。9は定着装置であり、本実施例において定着装置は、互いに圧接させた加熱ローラ9aと加圧ローラ9bとから構成されており、用紙に転写されたトナー像を定着させる。10aと10bはゲートで、搬送される用紙の方向を切り替える機能を有する。13は排出する用紙をスイッチバック反転させる反転器で、用紙の排出方向を変換する機能を有する。   In the printer 1, reference numerals 3, 4, and 5 denote image recording material storage units that store paper as image recording materials. Reference numeral 6 denotes a photosensitive drum, which starts rotating in the direction of an arrow based on a signal from a controller (not shown). When the photosensitive drum 6 starts rotating, the surface of the photosensitive drum 6 is uniformly charged by a corona charger (not shown). An electrostatic latent image is formed on the charged photosensitive drum 6 by a laser beam emitted from an exposure device (not shown). When the electrostatic latent image reaches the position of the developing device 7, the electrostatic latent image is developed with toner and visualized as a toner image on the photosensitive drum 6. Thus, the toner image formed by the well-known electrophotographic process is transferred by the transfer device 8 to the sheet sent out from the image recording material accommodating portions 3, 4, 5 or the return path 14 described later. Reference numeral 9 denotes a fixing device. In this embodiment, the fixing device is composed of a heating roller 9a and a pressure roller 9b that are brought into pressure contact with each other, and fixes the toner image transferred to the paper. Reference numerals 10a and 10b denote gates which have a function of switching the direction of the conveyed paper. Reference numeral 13 denotes an inverter that switches back and reverses the paper to be discharged, and has a function of changing the paper discharge direction.

なお、プリンタ1内に構成された用紙搬送路に関し、以下の説明においては、便宜上、画像記録材収容部3,4,5−画像形成手段6,7,8−プリンタ1の用紙排出口11を連絡する用紙搬送路12を「送紙路」と呼ぶ。14は「戻し路」と呼ぶこととし、送紙路12からゲ−ト10aにより分岐し、その終端を画像形成手段6,7,8に対し用紙搬送方向上流側の送紙路12に合流させて設けられている。15はゲート10aと10bの前段に設けられた搬送ローラ対である。   In the following description regarding the paper conveyance path configured in the printer 1, for convenience, the image recording material storage portions 3, 4, 5 -image forming means 6, 7, 8 -the paper discharge port 11 of the printer 1 The paper conveyance path 12 to be contacted is called a “paper feeding path”. 14 is referred to as a “return path”, branches from the paper feed path 12 by the gate 10a, and joins the end to the paper feed path 12 on the upstream side in the paper conveyance direction with respect to the image forming means 6, 7, and 8. Is provided. Reference numeral 15 denotes a transport roller pair provided in front of the gates 10a and 10b.

なお、図2において、3a,4a,5aは画像記録材収容部3,4,5に収容された用紙を繰り出すピックローラ、3b,4b,5bは一般にフィードローラとリタードローラから構成されることで知られる給紙ローラ対である。給紙ローラ対3b,4b,5bは、ピックローラ3a,4a,5aによって繰り出された用紙が複数枚重なった状態で搬送されるのを防止しながら用紙を一枚ずつ送紙路12へ供給する機能を有する。   In FIG. 2, 3a, 4a, and 5a are pick rollers for feeding out the paper stored in the image recording material storage units 3, 4, and 5, and 3b, 4b, and 5b are generally constituted by a feed roller and a retard roller. This is a known paper feed roller pair. The pair of paper feed rollers 3b, 4b, and 5b supplies the paper one by one to the paper feed path 12 while preventing the paper fed out by the pick rollers 3a, 4a, and 5a from being conveyed in a state where a plurality of sheets are overlapped. It has a function.

12a,12b,12cは送紙路12内の用紙を搬送する搬送ローラ対、12dはレジストローラ対12eの上流にあって、レジストローラ対12eに用紙を供給するためのタイミングロ−ラ対、12eは感光ドラム6上に形成されたトナー像を用紙へ転写させるタイミングに同期させて、用紙の搬送を行うレジストローラ対である。14a,14b,14c,14d,14e,14fは、戻し路14内の用紙を搬送する搬送ローラ対である。   12a, 12b, and 12c are a pair of conveying rollers for conveying the sheet in the sheet feeding path 12, and 12d is a timing roller pair for supplying the sheet to the registration roller pair 12e, upstream of the registration roller pair 12e, 12e. Is a pair of registration rollers that convey the paper in synchronism with the timing at which the toner image formed on the photosensitive drum 6 is transferred to the paper. Reference numerals 14 a, 14 b, 14 c, 14 d, 14 e, and 14 f are conveyance roller pairs that convey the paper in the return path 14.

次に図1、図3を用いて本発明の特徴である定着装置導入ガイド部材の構造を説明する。図1は本発明の定着装置の概略構成図である。   Next, the structure of the fixing device introduction guide member, which is a feature of the present invention, will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a fixing device of the present invention.

加熱ローラ9aの内部には、ハロゲンランプ等の加熱手段(図示せず)が備えられている。通常加熱ローラ9aは、円筒状の芯金の表面にトナーの離形性を向上するためのフッ素樹脂またはシリコンゴムをコーティングしたものである。フッ素系樹脂層は、PFA樹脂のチュービングで形成してもよく、PFA樹脂を焼き付けてもよい。また、加熱ローラ9aの外形は中央部が細く端部が太い、所謂アンダークラウン形状に成形されている。加圧ローラ9bは芯金の表面に耐熱性の高いシリコンゴムを弾性体層として設け、表面に離形性の良いPFAをチュービングしたものが主流である。前記加熱ローラ9aと加圧ローラ9bで構成する定着ローラ対は、ばね力を用いた加圧手段(図示せず)により、互いに押し付けられ、加圧ローラ9aの弾性体層の変形により面的に接触する。この接触面をニップ部と言う。前記加熱ローラ9aと加圧ローラ9bは前記ニップ部を形成した状態で定着ローラ対駆動手段とローラ駆動制御手段によって1方向に回転駆動される。   Heating means (not shown) such as a halogen lamp is provided inside the heating roller 9a. Usually, the heating roller 9a is formed by coating the surface of a cylindrical cored bar with a fluororesin or silicon rubber for improving toner releasability. The fluorine-based resin layer may be formed by PFA resin tubing, or PFA resin may be baked. Further, the outer shape of the heating roller 9a is formed in a so-called under crown shape with a narrow central portion and a thick end portion. As the pressure roller 9b, the mainstream is one in which a silicon rubber having a high heat resistance is provided as an elastic layer on the surface of the core metal and a PFA having a good releasability is tubing on the surface. The fixing roller pair composed of the heating roller 9a and the pressure roller 9b is pressed against each other by a pressing means (not shown) using a spring force, and is surface-formed by deformation of the elastic layer of the pressure roller 9a. Contact. This contact surface is called a nip portion. The heating roller 9a and the pressure roller 9b are rotationally driven in one direction by a fixing roller pair driving unit and a roller driving control unit in a state where the nip portion is formed.

周知の電子写真プロセスにより感光ドラム6上に可視化されたトナー像は転写器8により画像記録材である用紙22に転写され、送紙路12上を加熱ローラ9aと加圧ローラ9bからなる前記ニップ部へと運ばれる。その途中、定着導入ガイド部材16は下流端が前記加熱ローラ9aと前記加圧ローラ9bの中心を結ぶ直線に直行する加熱ローラ9aと前記加圧ローラ9bのニップ平面に対して加熱ローラ9a側に位置するように構成し、用紙22を前記ニップ部へと案内する作用を果たす。この一連のプロセスにより、用紙22上に形成されたトナー像は加熱ローラ9aと加圧ローラ9bの前記ニップで加熱と同時に加圧され用紙22に定着される。   The toner image visualized on the photosensitive drum 6 by a known electrophotographic process is transferred to the paper 22 as an image recording material by the transfer device 8, and the nip comprising the heating roller 9 a and the pressure roller 9 b on the paper feeding path 12. Carried to the department. On the way, the fixing introduction guide member 16 is located on the heating roller 9a side with respect to the nip plane between the heating roller 9a and the pressure roller 9b whose downstream end is perpendicular to the straight line connecting the centers of the heating roller 9a and the pressure roller 9b. The sheet 22 is configured to be positioned and serves to guide the sheet 22 to the nip portion. Through this series of processes, the toner image formed on the paper 22 is pressed simultaneously with the heating at the nip between the heating roller 9a and the pressure roller 9b and fixed on the paper 22.

図3は本発明の定着装置導入ガイド部材の外形図である。図3に示すように、定着装置導入ガイド部材16のガイド面の下流端は加熱ローラ9aと加圧ローラ9bの中心を結ぶ直線に直行する加熱ローラ9aと加圧ローラ9bのニップ平面に対して加熱ローラ9a側に位置するように構成し、且つガイド面下流端中央部は両端部に対してガイド面方向に上流側に凹となる方向に湾曲して成形されている。図4に示す定着装置導入ガイド部材16においても、両端部に対して中央部が加圧ローラ9b側に凹となる方向に湾曲しているため、用紙22の定着装置導入ガイド部材16からの持ち上がり量が低減され、加熱ローラ9aと接触し難くなる。   FIG. 3 is an external view of the fixing device introduction guide member of the present invention. As shown in FIG. 3, the downstream end of the guide surface of the fixing device introduction guide member 16 is in relation to the nip plane between the heating roller 9a and the pressure roller 9b that is orthogonal to the straight line connecting the centers of the heating roller 9a and the pressure roller 9b. It is configured so as to be positioned on the heating roller 9a side, and the guide surface downstream end central portion is curved and shaped in a direction that is concave toward the upstream side in the guide surface direction with respect to both ends. Also in the fixing device introduction guide member 16 shown in FIG. 4, the center portion is curved in a direction that is concave toward the pressure roller 9 b with respect to both ends, so that the sheet 22 is lifted from the fixing device introduction guide member 16. The amount is reduced, making it difficult to contact the heating roller 9a.

図3に示す定着装置導入ガイド部材と従来の下流端が直線の同一面を有する定着装置導入ガイド部材を用いて、画像記録材上の画像乱れの発生状況比較を、以下の実験条件で行った。その結果を表1に示す。

(実験条件1)
・記録材:サイズ(14インチ×18インチ)、重さ(75g/cm)、目方向(横目)
・印刷パターン:印字密度50%のハーフトーン
・印刷モード:両面印刷
・紙送り方向:SEF(Short Edge Feed)
・定着ローラの線速度:726.4mm/sec(感光体の線速度と同一)
・定着温度:190℃
・評価枚数:100枚
・評価方法:A4サイズ用紙を1,000枚通紙後に、評価用紙を100枚通紙し、その100枚中に発生した印刷乱れの件数を計数した。
・評価定着装置導入ガイド部材
A:従来の定着装置導入ガイド部材(下流端;直線)
C:本発明の定着装置導入ガイド部材(下流端;搬送方向に凹で、凹量10mm)
D:本発明の定着装置導入ガイド部材(下流端;搬送方向に凹で、凹量20mm)
Using the fixing device introduction guide member shown in FIG. 3 and the conventional fixing device introduction guide member whose downstream end has a straight surface, a comparison of the occurrence of image disturbance on the image recording material was performed under the following experimental conditions. . The results are shown in Table 1.

(Experimental condition 1)
Recording material: size (14 inches × 18 inches), weight (75 g / cm 2 ), eye direction (horizontal eye)
-Print pattern: halftone with 50% print density-Print mode: Double-sided printing-Paper feed direction: SEF (Short Edge Feed)
-Linear speed of fixing roller: 726.4 mm / sec (same as linear speed of photosensitive member)
Fixing temperature: 190 ° C
Evaluation sheet number: 100 Evaluation method: After passing 1,000 A4 size sheets, 100 evaluation sheets were passed, and the number of printing disturbances that occurred in the 100 sheets was counted.
Evaluation fixing device introduction guide member A: Conventional fixing device introduction guide member (downstream end; straight line)
C: Fixing device introduction guide member of the present invention (downstream end; concave in the conveyance direction, concave amount 10 mm)
D: Fixing device introduction guide member of the present invention (downstream end; concave in the conveyance direction, concave amount 20 mm)

Figure 2009175458
Figure 2009175458

以上のように、画像乱れの発生件数は、CとDの定着装置導入ガイド部材全てにおいて、Aの定着装置導入ガイド部材に対して大幅に改善することができた。また、CとDの比較から、凹み量が大きい程効果が大きいことが分かる。   As described above, the number of occurrences of image disturbance can be greatly improved in all of the C and D fixing device introduction guide members compared to the A fixing device introduction guide member. In addition, it can be seen from the comparison between C and D that the effect is greater as the amount of dent is larger.

図4は本発明における定着装置の駆動方式の概略構成図である。図4において、17は例えばステッピングモータとギヤトレインで構成された定着ローラ駆動機構、18は画像記録材のサイズ及び重量を記録するための、例えば操作パネル等の入力手段または記録材の収納部に備え付けられたセンサで画像記録材のサイズ及び重量を検知する検知手段で構成された画像記録材のサイズ及び重量の記録手段、19は前記画像記録材のサイズ、重量の記録手段18により記録された画像記録材サイズの幅または長さが予め設定した値を超えた場合に定着ローラ対のニップ部の線速度を感光体の線速度(以下、プロセス速度と称す)よりも遅い第二の速度に前記定着ローラ駆動機構の回転数を制御する定着ローラの駆動制御手段である。   FIG. 4 is a schematic configuration diagram of a driving method of the fixing device according to the present invention. In FIG. 4, 17 is a fixing roller driving mechanism composed of, for example, a stepping motor and a gear train, and 18 is an input means such as an operation panel for recording the size and weight of the image recording material or a recording material storage portion. An image recording material size and weight recording means composed of a detecting means for detecting the size and weight of the image recording material by the provided sensor, 19 is recorded by the image recording material size and weight recording means 18 When the width or length of the image recording material size exceeds a preset value, the linear velocity at the nip portion of the fixing roller pair is set to a second velocity that is slower than the linear velocity of the photosensitive member (hereinafter referred to as process velocity). It is a fixing roller driving control means for controlling the rotation speed of the fixing roller driving mechanism.

図4での定着装置の駆動方式を用いて、本発明における定着装置導入ガイド部材D(下流端;搬送方向に凹で、凹量20mm)と、従来の定着装置導入ガイド部材A(下流端が直線の同一面を有するもの)とを用いて、概略プロセス速度(本実施例では、726.4mm/sec)の定着ローラの線速度を標準とし(即ち、定着ローラの線速度はプロセス速度と同一)、標準からの低下率で示す定着ローラの線速度による画像記録材上の画像乱れの発生状況比較を、以下の実験条件で行った。その結果を表2に示す。

(実験条件2)
・記録材:サイズ(14インチ×18インチ)、重さ(75g/cm)、目方向(横目)
・印刷パターン:印字密度50%のハーフトーン
・印刷モード:両面印刷
・紙送り方向:SEF(Short Edge Feed)
・定着ローラの線速度:726.4mm/sec(標準)、721.315mm/sec(−0.7%)、719.136mm/sec(−1.0%)
・定着温度:195℃
・評価枚数:100枚
・評価方法:A4サイズ用紙を1,000枚通紙後に、評価用紙を100枚通紙し、その100枚中に発生した印刷乱れの件数を計数した。
・評価定着装置導入ガイド部材
A:従来の定着装置導入ガイド部材(下流端;直線)
D:本発明の定着装置導入ガイド部材(下流端;搬送方向に凹で、凹量20mm)
4, the fixing device introduction guide member D (downstream end; concave in the transport direction, concave amount 20 mm) and the conventional fixing device introduction guide member A (downstream end is the downstream end; The linear velocity of the fixing roller at an approximate process speed (726.4 mm / sec in this embodiment) is used as a standard (that is, the linear velocity of the fixing roller is the same as the process speed). ) Comparison of the occurrence of image disturbance on the image recording material according to the linear velocity of the fixing roller indicated by the rate of decrease from the standard was performed under the following experimental conditions. The results are shown in Table 2.

(Experimental condition 2)
Recording material: size (14 inches × 18 inches), weight (75 g / cm 2 ), eye direction (horizontal eye)
-Print pattern: halftone with 50% print density-Print mode: Double-sided printing-Paper feed direction: SEF (Short Edge Feed)
Fixing roller linear velocity: 726.4 mm / sec (standard), 721.315 mm / sec (−0.7%), 719.136 mm / sec (−1.0%)
Fixing temperature: 195 ° C
Evaluation sheet number: 100 Evaluation method: After passing 1,000 sheets of A4 size paper, 100 evaluation sheets were passed, and the number of printing disturbances occurring in the 100 sheets was counted.
Evaluation fixing device introduction guide member A: Conventional fixing device introduction guide member (downstream end; straight line)
D: Fixing device introduction guide member of the present invention (downstream end; concave in the conveyance direction, concave amount 20 mm)

Figure 2009175458
Figure 2009175458

以上のように、画像乱れの発生件数は、定着ローラの線速度をプロセス速度に対して0.7%低下させた場合に良い結果が得られることが分かる。また、Dの定着装置導入ガイド部材との組み合わせにより、大幅に改善できることが分かる。   As described above, it can be seen that the number of occurrences of image disturbance is good when the linear velocity of the fixing roller is reduced by 0.7% with respect to the process speed. Further, it can be seen that the combination with the fixing device introduction guide member D can greatly improve.

図5は本発明における他の定着装置の駆動方式の概略構成図である。図5において、17は定着ローラ駆動機構、18は記録手段、20は印刷開始後の印刷枚数を係数する印刷枚数計数手段である。19は定着ローラの駆動制御手段で、定着ローラの線速度を概略プロセス速度に制御して印刷を開始させるが、記録手段18により記録された画像記録材サイズの幅または長さが予め設定した値を超えている場合に、印刷枚数計数手段20により計数された枚数が、予め設定した枚数に達した後プロセス速度よりも遅い第二の速度に駆動手段の回転数を制御する定着ローラの駆動制御手段である。   FIG. 5 is a schematic configuration diagram of another driving method of the fixing device according to the present invention. In FIG. 5, numeral 17 is a fixing roller driving mechanism, numeral 18 is a recording means, and numeral 20 is a printed sheet number counting means for calculating the number of printed sheets after printing is started. Reference numeral 19 denotes a fixing roller drive control means for controlling the linear speed of the fixing roller to an approximate process speed to start printing. The width or length of the image recording material size recorded by the recording means 18 is a preset value. If the number of printed sheets counted by the printed sheet counting means 20 reaches a preset number, the driving control of the fixing roller that controls the rotation speed of the driving means to a second speed slower than the process speed is reached. Means.

ここで、従来の定着装置導入ガイド部材A(下流端;直線)を用いて、定着ローラを概略プロセス速度に制御した場合の画像記録材上の画像乱れが発生し始めるまでの印刷枚数を、以下の実験条件で調査した。その結果を表3に示す。

(実験条件3)
・記録材A:サイズ(14インチ×18インチ)、重さ(75g/cm)、目方向(横目)、含水率(6.1%)
・記録材B:サイズ(14インチ×18インチ)、重さ(81.4g/cm)、目方向(縦目)、含水率(6.4%)
・印刷パターン:印字密度50%のハーフトーン
・印刷モード:両面印刷
・定着ローラの線速度:726.4mm/sec
・紙送り方向:SEF(Short Edge Feed)
・評価定着装置導入ガイド部材:従来の定着装置導入ガイド部材A(下流端;直線)
・評価方法:上記条件で連続印刷を行い、画像乱れが発生し始める印刷頁数を計数した(通常、頁の計数は、1頁を送り方向で8.5インチ単位とし、第一面、第二面をそれぞれ1頁として行うが、便宜上14インチ×18インチ用紙の両面印刷は1枚で4頁と計数した)。
Here, when the fixing roller introduction guide member A (downstream end; straight line) is used and the fixing roller is controlled to the approximate process speed, the number of printed sheets until image disturbance on the image recording material starts to occur is as follows. The experimental conditions were investigated. The results are shown in Table 3.

(Experimental condition 3)
Recording material A: Size (14 inches × 18 inches), weight (75 g / cm 2 ), eye direction (landscape), moisture content (6.1%)
Recording material B: Size (14 inches × 18 inches), weight (81.4 g / cm 2 ), eye direction (longitudinal), moisture content (6.4%)
-Print pattern: halftone with a print density of 50%-Print mode: duplex printing-Linear speed of fixing roller: 726.4 mm / sec
-Paper feed direction: SEF (Short Edge Feed)
Evaluation fixing device introduction guide member: Conventional fixing device introduction guide member A (downstream end; straight line)
Evaluation method: Continuous printing was performed under the above conditions, and the number of printed pages where image disturbance started to occur was counted (usually, the page count was 8.5 inches in the feed direction, the first side, The two sides are each set as one page, but for convenience, double-sided printing of 14 inch × 18 inch paper was counted as 4 pages per sheet).

Figure 2009175458
Figure 2009175458

以上のように、画像乱れは印刷開始直後には発生し難く、概ね700頁印刷後から発生していることが分かる。一方、本発明のように定着ローラの線速度を低下させる技術には、薄紙や縦目用紙でしわに対する裕度が低下する場合がある。   As described above, it can be understood that the image disturbance hardly occurs immediately after the start of printing, and has generally occurred after 700 pages are printed. On the other hand, the technique for reducing the linear velocity of the fixing roller as in the present invention may reduce the tolerance to wrinkles with thin paper or vertical paper.

本発明における定着装置導入ガイド部材(D:本発明の定着装置導入ガイド部材(下流端;搬送方向に凹で、凹量20mm))を用いて、定着ローラの線速度をプロセス速度に対して約0.7%低下(即ち、定着ローラの線速度は、mm/sec)した場合での画像記録材上に、しわの予兆である画像にじみが発生する状況を、以下の実験条件で行った。その結果を表4に示す。

(実験条件4)
・記録材A:サイズ(14インチ×18インチ)、重さ(75g/cm)、目方向(横目)、含水率(6.1%)
・記録材B:サイズ(14インチ×18インチ)、重さ(81.4g/cm)、目方向(縦目)、含水率(6.4%)
・印刷パターン:印字密度33%の横線(ライン幅2ドット、スペース幅4ドット)
・印刷モード:両面印刷
・定着ローラの線速度:726.4mm/sec(標準)、721.315mm/sec(−0.7%)
・紙送り方向:SEF(Short Edge Feed)
・評価定着装置導入ガイド部材:定着装置導入ガイド部材D(下流端;搬送方向に凹で、凹量20mm)
・評価方法:上記条件で連続印刷を行い、しわの予兆である画像にじみが発生した印刷頁数を計数した(通常、頁の計数は、1頁を送り方向で8.5インチ単位とし、第一面、第二面をそれぞれ1頁として行うが、便宜上14インチ×18インチ用紙の両面印刷は1枚で4頁と計数した)。
By using the fixing device introduction guide member (D: the fixing device introduction guide member of the present invention (downstream end; concave in the transport direction, concave amount 20 mm)) according to the present invention, the linear velocity of the fixing roller is about the process speed. Under the following experimental conditions, an image recording material, which is a sign of wrinkles, was generated on the image recording material when 0.7% reduction (that is, the linear velocity of the fixing roller was mm / sec). The results are shown in Table 4.

(Experimental condition 4)
Recording material A: Size (14 inches × 18 inches), weight (75 g / cm 2 ), eye direction (landscape), moisture content (6.1%)
Recording material B: Size (14 inches × 18 inches), weight (81.4 g / cm 2 ), eye direction (longitudinal), moisture content (6.4%)
・ Printing pattern: Horizontal line with printing density of 33% (line width 2 dots, space width 4 dots)
-Printing mode: Duplex printing-Linear speed of fixing roller: 726.4 mm / sec (standard), 721.315 mm / sec (-0.7%)
-Paper feed direction: SEF (Short Edge Feed)
Evaluation fixing device introduction guide member: Fixing device introduction guide member D (downstream end; concave in the transport direction, concave amount 20 mm)
・ Evaluation method: Continuous printing was performed under the above conditions, and the number of printed pages in which image blurring, which is a sign of wrinkles, was counted. (One side and the second side are each set as one page, but for convenience, double-sided printing of 14 inch × 18 inch paper is counted as 4 pages per sheet).

Figure 2009175458
Figure 2009175458

以上のように、印刷にじみは印刷開始直後の約100頁以内の現象であり、100頁以後では発生しないことがわかる。このことから、本発明においては、印刷開始直後から100頁目までは定着ローラの線速度を概略プロセス速度とし、100頁以降は定着ローラの線速度をプロセス速度より0.7%遅い第二の速度で駆動することで、しわと画像乱れを両立して低減することができた。   As described above, it is understood that printing bleeding is a phenomenon within about 100 pages immediately after the start of printing, and does not occur after 100 pages. Therefore, in the present invention, the linear speed of the fixing roller is set to the approximate process speed immediately after the start of printing until the 100th page, and the linear speed of the fixing roller is 0.7% slower than the process speed after the 100th page. By driving at a speed, wrinkles and image disturbance could be reduced at the same time.

以上説明したように本発明によれば、薄紙で且つA3サイズ以上の大判用紙を使用した印刷の場合にも、定着しわや画像乱れのない画像形成装置を提供することが可能である。   As described above, according to the present invention, it is possible to provide an image forming apparatus that is free from fixing wrinkles and image distortion even in the case of printing using thin paper and large format paper of A3 size or larger.

本発明の実施例に係る定着装置の概略構成図である。1 is a schematic configuration diagram of a fixing device according to an embodiment of the present invention. 本発明の実施例に係る画像形成装置システムの全体構成図である。1 is an overall configuration diagram of an image forming apparatus system according to an embodiment of the present invention. 本発明の実施例に係る第2の定着装置導入ガイド部材の外形図である。FIG. 6 is an external view of a second fixing device introduction guide member according to an embodiment of the present invention. 本発明の実施例に係る定着装置の駆動方式の概略構成図である。1 is a schematic configuration diagram of a driving method of a fixing device according to an embodiment of the present invention. 本発明の実施例に係る他の定着装置の駆動方式の概略構成図である。It is a schematic block diagram of the drive system of the other fixing apparatus which concerns on the Example of this invention. 従来の電子写真式画像形成装置の定着装置及び定着装置周辺の画像記録材搬送機構の構造を簡略的に示した図である。FIG. 6 is a diagram schematically illustrating a structure of a fixing device of a conventional electrophotographic image forming apparatus and an image recording material transport mechanism around the fixing device.

符号の説明Explanation of symbols

1は画像形成装置(プリンタ)、2は用紙取扱装置(スタッカ)、3,4,5は画像記録材収納部、6は感光体、7は現像装置、8は転写器、9は定着装置、9aは加熱ローラ、9bは加圧ローラ、10a,10bはゲート、11は排出口、12は送紙路、12a,12b,12cは搬送ローラ対、12dはタイミングローラ対、12eはレジストローラ対、13は反転機、14は戻し路、15は搬送ローラ対、16は定着装置導入ガイド部材、17は定着ローラ駆動手段、18は画像記録材のサイズ、重量の記録手段、19は定着ローラ駆動制御手段、20は印刷枚数計数手段、22は用紙である。   1 is an image forming apparatus (printer), 2 is a paper handling apparatus (stacker), 3, 4 and 5 are image recording material storage units, 6 is a photosensitive member, 7 is a developing device, 8 is a transfer device, 9 is a fixing device, 9a is a heating roller, 9b is a pressure roller, 10a and 10b are gates, 11 is a discharge port, 12 is a paper feed path, 12a, 12b and 12c are transport roller pairs, 12d is a timing roller pair, 12e is a registration roller pair, 13 is a reversing machine, 14 is a return path, 15 is a conveying roller pair, 16 is a fixing device introduction guide member, 17 is a fixing roller driving unit, 18 is a recording unit for the size and weight of an image recording material, and 19 is a fixing roller driving control. Means, 20 is a printed sheet counting means, and 22 is paper.

Claims (3)

感光体上に現像されたトナー像を画像記録材に転写するための転写装置と前記画像記録材上に転写されたトナーを加熱加圧することで画像記録材に定着させるための定着装置をつなぐ搬送経路上に、前記定着装置を構成する加熱ローラと加圧ローラのニップ部に前記画像記録材を案内する定着装置導入ガイド部材を前記加熱ローラと加圧ローラの直上流の加圧ローラ側に設け、前記定着装置導入ガイド部材のガイド面の画像記録材搬送方向の最下流端が前記加熱ローラと前記加圧ローラの中心を結ぶ直線に直行する加熱ローラと前記加圧ローラのニップ点を含むニップ平面に対して加熱ローラ側に位置するように構成し、前記定着装置導入ガイド部材により案内される画像記録材先端が先に前記加熱ローラに接触する位置関係として、前記定着装置導入ガイド部材のガイド面の下流側の稜線を中央部が該稜線の両端部よりも上流側に凹になる曲線で構成していることを特徴とする画像形成装置。   Conveyance connecting a transfer device for transferring a toner image developed on a photoreceptor to an image recording material and a fixing device for fixing the toner transferred on the image recording material by heating and pressing the toner image On the path, a fixing device introduction guide member for guiding the image recording material to a nip portion between the heating roller and the pressure roller constituting the fixing device is provided on the pressure roller side immediately upstream of the heating roller and the pressure roller. A nip including a nip point between the heating roller and the pressure roller, the most downstream end of the guide surface of the fixing device introduction guide member in the image recording material conveyance direction goes straight to a straight line connecting the center of the heating roller and the pressure roller. It is configured so as to be positioned on the heating roller side with respect to the plane, and the positional relationship in which the front end of the image recording material guided by the fixing device introduction guide member first contacts the heating roller is the above-described fixed relationship. Image forming apparatus, wherein a ridge line of the downstream side of the guide surface of the device introduction guide member central portion constitutes a curve which is concave on the upstream side of the both end portions of the 該稜 line. 給紙トレイと給紙トレイにセットされた画像記録材のサイズを検出する検出手段または、オペレータが画像記録材サイズを入力する入力手段あるいは前記検出手段と前記入力手段の両方と前記検出手段または入力手段で入力した画像記録材サイズ情報を記録するための書換え可能なメモリー手段と感光体上に現像されたトナー像を画像記録材に転写するための転写装置と前記画像記録材上に転写されたトナーを加熱加圧することで画像記録材に定着させるための定着装置を具備し、前記定着装置を加熱ローラと前記加熱ローラに押圧されてニップを形成する加圧ローラの定着ローラ対で構成し、前記定着ローラ対を回転駆動する駆動手段と前記定着ローラ対のニップ部の線速度を前記感光体の線速度と概略同速度に前記回転駆動手段の回転数を制御するための制御手段を具備し、使用する画像記録材サイズの幅または長さが予め設定した画像記録材サイズを超えた場合には前記定着ローラ対のニップ部の線速度を前記感光体の線速度よりも遅い第二の速度に前記駆動手段の回転数を制御することを特徴とした請求項1記載の画像形成装置。   Detection means for detecting the size of the image recording material set in the paper supply tray and the paper supply tray, or input means for the operator to input the size of the image recording material, or both of the detection means and the input means, and the detection means or input Rewritable memory means for recording image recording material size information inputted by the means, a transfer device for transferring the toner image developed on the photoreceptor to the image recording material, and the image recording material transferred onto the image recording material A fixing device for fixing the image recording material by heating and pressurizing the toner, and the fixing device is composed of a heating roller and a fixing roller pair of pressure rollers that are pressed by the heating roller to form a nip; The rotational speed of the rotational driving means is set so that the linear speed of the nip portion of the driving means for rotating the fixing roller pair and the fixing roller pair is substantially the same as the linear speed of the photosensitive member. Control means for controlling, and when the width or length of the size of the image recording material to be used exceeds a preset image recording material size, the linear velocity of the nip portion of the fixing roller pair is set on the photosensitive member. 2. The image forming apparatus according to claim 1, wherein the rotational speed of the driving unit is controlled to a second speed slower than the linear speed. 給紙トレイと給紙トレイにセットされた画像記録材のサイズを検出する検出手段または、オペレータが画像記録材サイズを入力する入力手段あるいは前記検出手段と前記入力手段の両方と前記検出手段または入力手段で入力した画像記録材サイズ情報を記録するための書換え可能なメモリー手段と印刷開始後の印刷枚数を計数する計数手段と感光体上に現像されたトナー像を画像記録材に転写するための転写装置と前記画像記録材上に転写されたトナーを加熱加圧することで画像記録材に定着させるための定着装置を具備し、前記定着装置を加熱ローラと前記加熱ローラに押圧されてニップを形成する加圧ローラの定着ローラ対で構成し、前記定着ローラ対を回転駆動する駆動手段と前記定着ローラ対のニップ部の線速度を前記感光体の線速度と概略同速度に前記回転駆動手段の回転数を制御するための制御手段を具備し、印刷開始時には前記感光体の線速度で前記駆動手段の回転数を制御し、予め設定した枚数の画像記録材を印刷した後、画像記録材サイズの幅または長さが予め設定した画像記録材サイズを超えている場合には前記加熱ローラと加圧ローラのニップ部の線速度を前記感光体の線速度よりも遅い第二の速度に前記駆動手段の回転数を制御することを特徴とした請求項1記載の画像形成装置。   Detection means for detecting the size of the image recording material set in the paper supply tray and the paper supply tray, or input means for the operator to input the size of the image recording material, or both of the detection means and the input means, and the detection means or input A rewritable memory means for recording the image recording material size information input by the means, a counting means for counting the number of printed sheets after the start of printing, and a toner image developed on the photosensitive member for transferring to the image recording material. A transfer device and a fixing device for fixing the toner transferred onto the image recording material to the image recording material by heating and pressurizing are provided. The fixing device is pressed by the heating roller and the heating roller to form a nip. A fixing roller pair of a pressure roller, and a linear velocity of a nip portion of the fixing roller pair and a driving unit that rotationally drives the fixing roller pair, and a linear velocity of the photosensitive member. And a control means for controlling the rotational speed of the rotational driving means at approximately the same speed as the above, and at the start of printing, the rotational speed of the driving means is controlled by the linear speed of the photosensitive member to record a predetermined number of images. After printing the material, when the width or length of the image recording material size exceeds the preset image recording material size, the linear velocity of the nip portion of the heating roller and the pressure roller is set to the linear velocity of the photoconductor. 2. The image forming apparatus according to claim 1, wherein the rotational speed of the driving unit is controlled to a second speed slower than the second speed.
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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5810457U (en) * 1981-07-09 1983-01-22 株式会社リコー Copy machine roller fixing device
JPS59128664U (en) * 1983-02-19 1984-08-29 京セラミタ株式会社 Copy machine fixing device
JPH01149668U (en) * 1988-04-05 1989-10-17
JPH02306279A (en) * 1989-05-20 1990-12-19 Hitachi Ltd Electrophotographic recorder
JPH0431163U (en) * 1990-07-04 1992-03-12
JP2005266505A (en) * 2004-03-19 2005-09-29 Canon Finetech Inc Image forming apparatus
JP2006091448A (en) * 2004-09-24 2006-04-06 Canon Inc Thermal fixing apparatus and image forming apparatus

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5810457U (en) * 1981-07-09 1983-01-22 株式会社リコー Copy machine roller fixing device
JPS59128664U (en) * 1983-02-19 1984-08-29 京セラミタ株式会社 Copy machine fixing device
JPH01149668U (en) * 1988-04-05 1989-10-17
JPH02306279A (en) * 1989-05-20 1990-12-19 Hitachi Ltd Electrophotographic recorder
JPH0431163U (en) * 1990-07-04 1992-03-12
JP2005266505A (en) * 2004-03-19 2005-09-29 Canon Finetech Inc Image forming apparatus
JP2006091448A (en) * 2004-09-24 2006-04-06 Canon Inc Thermal fixing apparatus and image forming apparatus

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