JP2011095306A - Fixing device - Google Patents

Fixing device Download PDF

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Publication number
JP2011095306A
JP2011095306A JP2009246337A JP2009246337A JP2011095306A JP 2011095306 A JP2011095306 A JP 2011095306A JP 2009246337 A JP2009246337 A JP 2009246337A JP 2009246337 A JP2009246337 A JP 2009246337A JP 2011095306 A JP2011095306 A JP 2011095306A
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fixing roller
fixing
roller
heating
fixing device
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JP2009246337A
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JP2011095306A5 (en
Inventor
Masashi Tanaka
正志 田中
Kenichi Ogawa
賢一 小川
Satoshi Nishida
聡 西田
Shuichi Tetsuno
修一 鉄野
Shogo Suga
祥吾 菅
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Canon Inc
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Canon Inc
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Priority to JP2009246337A priority Critical patent/JP2011095306A/en
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Publication of JP2011095306A5 publication Critical patent/JP2011095306A5/ja
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  • Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)
  • Laminated Bodies (AREA)
  • Fixing For Electrophotography (AREA)
  • Rolls And Other Rotary Bodies (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To reduce transfer of foreign substances adhering to the surface of a fixing roller onto a heating rotating member. <P>SOLUTION: A fixing device is provided, including a heating rotary member 120, a fixing roller 110 having an elastic rubber layer 116 and forming a heating nip N2 by coming into contact with the heating rotary member, and a backup member 111 coming into contact with the fixing roller to form a fixing nip N1, wherein the surface of the fixing roller is heated at the heating nip by the heating rotary member and while a recording material P carrying a toner image is held and conveyed at the fixing nip, the toner image t is fixed by heating to the recording material on the surface of the fixing roller. The micro hardness H&mu; of the surface of the fixing roller satisfies H&mu;&lt;50. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

本発明は、電子写真複写機や電子写真プリンタ等の画像形成装置に搭載する定着装置（定着器）に関する。   The present invention relates to a fixing device (fixing device) mounted on an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer.

電子写真式の複写機やプリンタ等に搭載する定着装置として、外部加熱方式の定着装置が知られている。この外部加熱方式の定着装置は、ヒータ等の加熱体と、この加熱体により加熱される定着ローラと、この定着ローラと共にニップ部を形成する加圧ローラと、を有している。未定着のトナー画像を担持する記録材はトナー像担持面を定着ローラ側に向けニップ部で挟持搬送されつつ加熱され、これにより記録材上のトナー像は記録材に加熱定着される。この外部加熱方式の定着装置としては、加熱体を定着ローラの外周面（表面）に接触させる接触式と、加熱体を定着ローラ表面に接触させずに定着ローラ表面を加熱する非接触式と、に大別される。接触式の外部加熱方式の定着装置は、セラミックヒータなどの加熱源を定着ローラ表面に接触させ熱を伝えるため、非接触式の外部加熱方式の定着装置に比べ熱の伝搬効率が高い。接触式の外部加熱方式の定着装置には、定着ローラ表面に加熱体を摺動させる摺動接触式の定着装置と、加熱体と接触しつつ回転する筒状の回転部材（以下、加熱回転部材と記す）を介して定着ローラに加熱体の熱を伝える回転接触式の定着装置と、に分けられる。回転接触式の定着装置は、定着ローラの回転に伴い加熱回転部材も回転するため、摺動接触式の定着装置に比べ定着ローラ表面を傷めにくく、また摩擦力が小さいため駆動トルクを抑えることができるという利点がある。特許文献１にはこのタイプの定着装置が開示されている。   As a fixing device mounted on an electrophotographic copying machine, a printer, or the like, an external heating type fixing device is known. This external heating type fixing device includes a heating body such as a heater, a fixing roller heated by the heating body, and a pressure roller that forms a nip portion together with the fixing roller. The recording material carrying the unfixed toner image is heated while being nipped and conveyed by the nip portion with the toner image carrying surface facing the fixing roller, whereby the toner image on the recording material is heated and fixed on the recording material. As an external heating type fixing device, a contact type in which a heating body is brought into contact with the outer peripheral surface (surface) of the fixing roller, a non-contact type in which the surface of the fixing roller is heated without bringing the heating body into contact with the surface of the fixing roller, and It is divided roughly into. Since the contact-type external heating type fixing device transmits heat by bringing a heating source such as a ceramic heater into contact with the surface of the fixing roller, the heat propagation efficiency is higher than that of a non-contact type external heating type fixing device. The contact-type external heating type fixing device includes a sliding contact type fixing device that slides a heating body on the surface of the fixing roller, and a cylindrical rotating member that rotates while contacting the heating body (hereinafter referred to as a heating rotating member). And a rotary contact type fixing device that transfers the heat of the heating body to the fixing roller. In the rotary contact type fixing device, the heating rotating member also rotates with the rotation of the fixing roller. Therefore, the surface of the fixing roller is less likely to be damaged than the sliding contact type fixing device, and the frictional force is small, so that the driving torque can be suppressed. There is an advantage that you can. Patent Document 1 discloses a fixing device of this type.

特開２００３−１８６３２７号公報JP 2003-186327 A

上記の回転接触式の定着装置では、定着ローラ表面が紙等の記録材上のトナー像と接触するため、微量の紙粉やトナーなどの異物が定着ローラ表面に付着するが、この定着ローラ表面に付着した異物を加熱回転部材に転移させないようにすることが望まれている。本発明の目的は、定着ローラ表面に付着した異物の加熱回転部材への転移を低減できるようにした定着装置を提供することにある。   In the above rotating contact type fixing device, since the surface of the fixing roller comes into contact with the toner image on the recording material such as paper, a small amount of foreign matter such as paper dust or toner adheres to the surface of the fixing roller. It is desired to prevent foreign matter adhering to the heat transfer member from being transferred to the heating rotary member. An object of the present invention is to provide a fixing device capable of reducing the transfer of foreign matter adhering to the surface of a fixing roller to a heating rotary member.

上記目的を達成するための本発明に係る定着装置の構成は、加熱回転部材と、弾性ゴム層を有する定着ローラであり前記加熱回転部材と接触して加熱ニップ部を形成する定着ローラと、前記定着ローラと接触して定着ニップ部を形成するバックアップ部材と、を有し、前記加熱回転部材は前記加熱ニップ部で前記定着ローラの表面を加熱し、前記定着ニップ部でトナー像を担持する記録材を挟持搬送しつつ前記定着ローラ表面でトナー像を記録材上に加熱定着する定着装置において、前記定着ローラ表面のマイクロ硬度をＨμとすると、Ｈμ＜５０を満たすことを特徴とする。   In order to achieve the above object, the fixing device according to the present invention includes a heating rotating member, a fixing roller having an elastic rubber layer, which contacts the heating rotating member to form a heating nip portion, and A backup member that forms a fixing nip portion in contact with the fixing roller, and the heating rotating member heats the surface of the fixing roller at the heating nip portion and carries a toner image at the fixing nip portion. In a fixing device that heats and fixes a toner image on a recording material on the surface of the fixing roller while nipping and conveying the material, if the micro hardness of the surface of the fixing roller is Hμ, Hμ <50 is satisfied.

本発明によれば、定着ローラ表面に付着した異物の加熱回転部材表面への転移を低減できるようにした定着装置を提供できる。   According to the present invention, it is possible to provide a fixing device that can reduce the transfer of the foreign matter adhering to the surface of the fixing roller to the surface of the heating rotary member.

（ａ）は実施例１に係る定着装置の構成を表わす横断面模式図、（ｂ）は（ａ）に示す定着装置の加熱ニップ部及びその近傍の横断面拡大図である。(A) is a cross-sectional schematic diagram showing the configuration of the fixing device according to the first embodiment, and (b) is a cross-sectional enlarged view of a heating nip portion and its vicinity of the fixing device shown in (a). （ａ）は定着ローラ表面のマイクロ硬度が低い場合の加熱フィルム表面への異物の転移を低減できるメカニズムの説明図、（ｂ）は定着ローラ表面のマイクロ硬度が高い場合に加熱フィルム表面に異物が転移するメカニズムの説明図である。(A) is an explanatory view of a mechanism that can reduce the transfer of foreign matter to the heating film surface when the micro hardness of the fixing roller surface is low, and (b) is a foreign matter on the heating film surface when the micro hardness of the fixing roller surface is high. It is explanatory drawing of the mechanism to transfer. （ａ）と（ｂ）は定着ローラ表面のマイクロ硬度と定着ローラ表面の異物の包み込み性との関係を調査する方法の説明図である。（ｃ）は定着ローラの離型層の厚み違いによる定着ローラ表面のマイクロ硬度と、定着ローラ表面のガラスビーズの密着性（包み込み性）の関係を調査した結果を表わす図である。(A) And (b) is explanatory drawing of the method of investigating the relationship between the micro hardness of the surface of a fixing roller, and the enveloping property of the foreign material on the surface of a fixing roller. (C) is a view showing a result of investigating the relationship between the micro hardness of the surface of the fixing roller due to the difference in the thickness of the release layer of the fixing roller and the adhesion (wrapping property) of the glass beads on the surface of the fixing roller. （ａ）は実施例２に係る定着装置における定着ローラの層構成を表わす横断面模式図である。（ｂ）は実施例５に係る定着装置の構成を表わす横断面模式図、（ｃ）は実施例６に係る定着装置の構成を表わす横断面模式図である。FIG. 6A is a schematic cross-sectional view illustrating a layer configuration of a fixing roller in a fixing device according to a second embodiment. FIG. 10B is a schematic cross-sectional view illustrating a configuration of a fixing device according to a fifth embodiment. FIG. 10C is a schematic cross-sectional view illustrating a configuration of the fixing device according to the sixth embodiment. 画像形成装置の一例の構成を表わす横断面模式図である。1 is a schematic cross-sectional view illustrating a configuration of an example of an image forming apparatus.

［実施例１］画像形成装置全体の構成：図５は本発明に係る定着装置を搭載する画像形成装置の一例の構成を表わす横断面模式図である。この画像形成装置は電子写真式のフルカラーレーザープリンタである。本実施例１に示す画像形成装置５０は、イエローＹ、マゼンタＭ、シアンＣ、ブラックＫの各色のトナー像を形成する第１から第４の４つの画像形成ステーション（画像形成部）ＳＹ，ＳＭ，ＳＭ，ＳＫを有している。画像形成ステーションＳＹ，ＳＭ，ＳＭ，ＳＫは、それぞれ、像担持体としてのドラム型の電子写真感光体（以下、感光ドラムと記す）１を有している。そしてこの感光ドラム１の回転方向に沿って順に、帯電手段としての帯電器２と、露光手段としての露光装置３と、現像手段としての現像器５と、クリーニング手段としてのドラムクリーナー８がそれぞれ配置されている。また画像形成ステーションＳＹ，ＳＭ，ＳＭ，ＳＫの感光ドラム１の外周面（表面）と対向するように記録材搬送手段としてのエンドレスの記録材搬送ベルト９が設けられている。この記録材搬送ベルト９は、駆動ローラ１２とテンションローラ１３の２軸に巻きかけられている。またこの記録材搬送ベルト９は、記録材Ｐを静電気を利用して保持できるように誘電体樹脂材料によって形成されている。そしてこの記録材搬送ベルト９を挟んで画像形成ステーションＳＹ，ＳＭ，ＳＭ，ＳＫの感光ドラム１と対向させて転写手段としての転写ローラ１０を配設することによって、感光ドラム１と記録材搬送ベルト９との間に転写部を形成している。本実施例１の画像形成装置５０は、ホストコンピュータ等の外部装置（不図示）から出力されるプリント信号に応じて所定の画像形成シーケンスを実行し、この画像形成シーケンスに従って画像形成動作を行なう。各感光ドラム１が矢印方向へ所定の周速度（プロセススピード）で回転される。また記録材搬送ベルト９が駆動ローラ１２の回転駆動により矢印方向へ感光ドラム１の回転周速度に対応した周速度で周回移動される。まず１色目のイエローの画像形成ステーションＳＹにおいて、感光ドラム１表面を帯電器２によって所定の極性・電位に一様に帯電する。本実施例１では感光ドラム１表面は負極性に帯電される。次に露光装置３が外部装置からの画像情報に応じたレーザー光Ｌを感光ドラム１表面の帯電面に走査露光する。これにより、感光ドラム１表面の帯電面に画像情報に応じた静電潜像が形成される。そしてこの静電潜像が現像器５によりイエローのトナー（現像剤）によって現像され、感光ドラム１表面にイエローのトナー像（現像像）が形成される。同様の、帯電、露光、現像の各工程が２色目のマゼンタの画像形成ステーションＳＭ、３色目のシアンの画像形成ステーションＳＣ、４色目のブラックの画像形成ステーションＳＫにおいても行なわれる。これにより画像形成ステーションＳＹ，ＳＭ，ＳＭ，ＳＫの各感光ドラム１表面に各色のトナー像（現像像）が形成される。一方、給送カセット７内に積載収容されている記録紙などの記録材Ｐは給送ローラ４により送り出される。その記録材Ｐは、正極性のバイアスが印加された吸着ローラ６によって帯電され、記録材搬送ベルト９の外周面（表面）上に静電吸着して記録材搬送ベルト９により保持される。そしてこの記録材Ｐは、記録材搬送ベルト９の周回移動によって記録材搬送ベルト９の回転方向上流側の転写部から回転方向下流側の転写部まで搬送される。各画像形成ステーションＳＹ，ＳＭ，ＳＣ，ＳＫの転写ローラ１０には記録材Ｐの搬送過程においてトナー像と逆極性の転写バイアスが印加される。各転写ローラ１０はその転写バイアスにより対応する感光体ドラム１表面のトナー像を記録材Ｐ上に順番に重ねて転写する。これによって記録材Ｐは記録材Ｐ上にフルカラーの未定着のトナー像を担持する。このトナー像を担持する記録材Ｐは記録材搬送ベルト９により加熱定着装置（定着器）１００に搬送される。そしてこの記録材Ｐは定着装置１００の後述する定着ニップ部Ｎ１を通過することによって記録材Ｐ上にトナー像が加熱定着される。定着装置１００を出た記録材Ｐは排出ローラ１１によって排出トレー１４上に排出される。トナー像転写後の感光体ドラム１表面に残留している転写残トナーはドラムクリーナー８によって除去され回収される。   [Embodiment 1] Overall Configuration of Image Forming Apparatus FIG. 5 is a schematic cross-sectional view showing the configuration of an example of an image forming apparatus equipped with a fixing device according to the present invention. This image forming apparatus is an electrophotographic full color laser printer. The image forming apparatus 50 according to the first exemplary embodiment includes four first to fourth image forming stations (image forming units) SY and SM that form toner images of respective colors of yellow Y, magenta M, cyan C, and black K. , SM, SK. Each of the image forming stations SY, SM, SM, and SK has a drum-type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 1 as an image carrier. A charger 2 as a charging unit, an exposure device 3 as an exposure unit, a developing unit 5 as a developing unit, and a drum cleaner 8 as a cleaning unit are arranged in order along the rotation direction of the photosensitive drum 1. Has been. Further, an endless recording material conveying belt 9 as a recording material conveying means is provided so as to face the outer peripheral surface (front surface) of the photosensitive drum 1 of the image forming stations SY, SM, SM, and SK. The recording material conveying belt 9 is wound around two axes of a driving roller 12 and a tension roller 13. The recording material transport belt 9 is formed of a dielectric resin material so that the recording material P can be held using static electricity. Then, the photosensitive drum 1 and the recording material conveyance belt are arranged by disposing a transfer roller 10 as a transfer unit so as to face the photosensitive drum 1 of the image forming stations SY, SM, SM, and SK with the recording material conveyance belt 9 interposed therebetween. 9 is formed between the transfer portion 9 and the transfer portion 9. The image forming apparatus 50 according to the first embodiment executes a predetermined image forming sequence in accordance with a print signal output from an external device (not shown) such as a host computer, and performs an image forming operation according to the image forming sequence. Each photosensitive drum 1 is rotated in the direction of the arrow at a predetermined peripheral speed (process speed). In addition, the recording material conveying belt 9 is rotated in the direction of the arrow by the rotational driving of the driving roller 12 at a peripheral speed corresponding to the rotational peripheral speed of the photosensitive drum 1. First, in the first color yellow image forming station SY, the surface of the photosensitive drum 1 is uniformly charged by the charger 2 to a predetermined polarity and potential. In Example 1, the surface of the photosensitive drum 1 is charged to a negative polarity. Next, the exposure device 3 scans and exposes the charged surface on the surface of the photosensitive drum 1 with a laser beam L corresponding to the image information from the external device. As a result, an electrostatic latent image corresponding to the image information is formed on the charging surface of the surface of the photosensitive drum 1. The electrostatic latent image is developed with yellow toner (developer) by the developing device 5, and a yellow toner image (development image) is formed on the surface of the photosensitive drum 1. Similarly, the charging, exposure, and development processes are performed in the second color magenta image forming station SM, the third color cyan image forming station SC, and the fourth color black image forming station SK. As a result, toner images (developed images) of the respective colors are formed on the surfaces of the photosensitive drums 1 of the image forming stations SY, SM, SM, and SK. On the other hand, the recording material P such as recording paper loaded and accommodated in the feeding cassette 7 is sent out by the feeding roller 4. The recording material P is charged by the suction roller 6 to which a positive bias is applied, electrostatically adsorbed onto the outer peripheral surface (front surface) of the recording material transport belt 9 and held by the recording material transport belt 9. Then, the recording material P is conveyed from the transfer portion on the upstream side in the rotation direction of the recording material conveyance belt 9 to the transfer portion on the downstream side in the rotation direction by the circular movement of the recording material conveyance belt 9. A transfer bias having a polarity opposite to that of the toner image is applied to the transfer rollers 10 of the image forming stations SY, SM, SC, and SK during the conveyance of the recording material P. Each transfer roller 10 transfers the toner image on the surface of the corresponding photosensitive drum 1 on the recording material P in order by transferring bias. As a result, the recording material P carries a full-color unfixed toner image on the recording material P. The recording material P carrying the toner image is conveyed to the heat fixing device (fixing device) 100 by the recording material conveyance belt 9. The recording material P passes through a fixing nip portion N1 (described later) of the fixing device 100, whereby a toner image is heated and fixed on the recording material P. The recording material P exiting the fixing device 100 is discharged onto the discharge tray 14 by the discharge roller 11. The transfer residual toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image is removed and collected by the drum cleaner 8.

定着装置の構成：以下の説明において、定着装置及びこの定着装置を構成する部材に関し、長手方向とは記録材の面において記録材搬送方向と直交する方向である。短手方向とは記録材の面において記録材搬送方向と平行な方向である。長さとは長手方向の寸法である。幅とは短手方向の寸法である。図１の（ａ）は本実施例１に係る定着装置の構成を表わす横断面模式図である。図１の（ｂ）は図１の（ａ）に示す定着装置の加熱ニップ部及びその近傍の横断面拡大図である。この定着装置は、外部加熱方式の定着装置であり、特にヒータと接触しつつ回転する加熱フィルムを定着ローラ表面に接触させる回転接触式の定着装置である。この回転接触式の定着装置は、ヒータへの通電を開始し定着可能温度（定着温度）まで昇温するのに要する時間が短い（立ち上げ時間の短縮）というメリットがある。また定着ローラの外周面のみを加熱するので消費電力が少ない（低消費電力化）というメリットもある。本実施例１に示す定着装置１００は、定着ローラ１１０と、バックアップ部材としての加圧ローラ１１１と、加熱回転部材としての加熱フィルム１２０と、加熱体としてのヒータ１１５などを有している。定着ローラ１１０は、定着ローラ１１０の外周面（表面）が加圧ローラ１１１の外周面（表面）と接触し加圧ローラ１１１と共に定着ニップ部Ｎ１を形成している。また定着ローラ１１０は、加圧ローラ１１１の反対側で定着ローラ１１０表面とヒータ１１５とにより加熱フィルム１２０を挟むことによって加熱ニップ部Ｎ２を形成している。以下に、各部材の構成をさらに詳しく説明する。   Configuration of Fixing Device: In the following description, with respect to the fixing device and members constituting the fixing device, the longitudinal direction is a direction orthogonal to the recording material conveyance direction on the surface of the recording material. The short side direction is a direction parallel to the recording material conveyance direction on the surface of the recording material. The length is a dimension in the longitudinal direction. The width is a dimension in the short direction. FIG. 1A is a schematic cross-sectional view illustrating the configuration of the fixing device according to the first embodiment. FIG. 1B is an enlarged cross-sectional view of the heating nip portion and its vicinity of the fixing device shown in FIG. This fixing device is an external heating type fixing device, and in particular, is a rotary contact type fixing device in which a heating film rotating while being in contact with a heater is brought into contact with the surface of the fixing roller. This rotary contact type fixing device has an advantage that the time required to start energization of the heater and to raise the temperature to a fixing possible temperature (fixing temperature) is short (start-up time is shortened). Further, since only the outer peripheral surface of the fixing roller is heated, there is an advantage that power consumption is low (low power consumption). The fixing device 100 shown in the first embodiment includes a fixing roller 110, a pressure roller 111 as a backup member, a heating film 120 as a heating rotation member, a heater 115 as a heating body, and the like. In the fixing roller 110, the outer peripheral surface (front surface) of the fixing roller 110 is in contact with the outer peripheral surface (front surface) of the pressure roller 111 to form a fixing nip portion N <b> 1 together with the pressure roller 111. The fixing roller 110 forms a heating nip portion N2 by sandwiching the heating film 120 between the surface of the fixing roller 110 and the heater 115 on the opposite side of the pressure roller 111. Below, the structure of each member is demonstrated in detail.

加圧ローラの構成：加圧ローラ１１１は、外径φ２０ｍｍのローラ状の部材である。この加圧ローラ１１１は、細長いφ１２ｍｍの鉄製の芯金１２１を有し、この芯金１２１の長手方向両端部の支持軸部以外の外周面上にシリコーンゴムを発泡した厚さ４ｍｍの弾性ゴム層１２２（発泡ゴム）を形成したものである。加圧ローラ１１１は、熱容量が大きく、且つ、熱伝導率が高いと、定着ニップ部Ｎ１で定着ローラ１１０表面の熱を奪い易い。また加圧ローラ１１１は、熱容量が大きく、且つ、熱伝導率が高いと、定着ニップ部Ｎ１で定着ローラ１１０表面から受ける熱が加圧ローラ１１１内部へ吸収され易いため、定着ローラ１１０及び加圧ローラ１１１の表面温度が上昇しにくくなる。すなわち、加圧ローラ１１１は、低熱容量で、且つ、熱伝導率が低く、断熱効果の高い方が、定着ローラ１１０の熱を奪いにくいため、定着ローラ１１０の表面温度の立ち上がり時間を短縮できる。上記シリコーンゴムを発泡した発泡ゴムの熱伝導率は０．１１〜０．１６Ｗ／ｍ・Ｋであり、０．２５〜０．２９Ｗ／ｍ・Ｋ程度のソリッドゴムよりも熱伝導率が低い。また、熱容量に関係する比重はソリッドゴムが約１．０５〜１．３０であるのに対して、発泡ゴムが約０．７５〜０．８５であり、低熱容量でもある。従って、加圧ローラ１１１の弾性ゴム層１２２として上記の発泡ゴムを用いることで定着ローラ１１０の表面温度の立ち上がり時間を短縮できる。加圧ローラ１１１の最表層にはＰＦＡからなる離型層１２３が設けられている。すなわち、弾性ゴム層１２２の外側（外周面上）には、フッ素系材料であるパーフルオロアルコキシ樹脂（ＰＦＡ）からなる離型層１２３が形成されている。離型層１２３は、弾性ゴム層１２２の外周面上にチューブを被覆させたもの、或いは弾性ゴム層１２２の外周面を塗料でコートしたものであっても良い。本実施例１では、離型層１２３として、耐久性の優れるチューブを使用した。離型層１２３の材料としては、ＰＦＡの他に、ポリテトラフルオロエチレン樹脂（ＰＴＦＥ）、テトラフルオロエチレン−ヘキサフルオロプロピレン樹脂（ＦＥＰ）等のフッ素樹脂や、離型性の良いフッ素ゴムやシリコーンゴム等を用いても良い。また加圧ローラ１１１は、加圧ローラ１１１の硬度が低ければ軽圧でも定着ニップ部Ｎ１に所定の幅を得ることができるが、低すぎると加圧ローラ１１１の耐久性が悪化する。このため、本実施例１では、加圧ローラ１１１の硬度をＡｓｋｅｒ−Ｃ硬度（４．９Ｎ荷重）で４０〜４５度とした。   Configuration of pressure roller: The pressure roller 111 is a roller-shaped member having an outer diameter of φ20 mm. The pressure roller 111 has an iron core bar 121 having a long and narrow diameter of 12 mm, and an elastic rubber layer having a thickness of 4 mm in which silicone rubber is foamed on the outer peripheral surface of the core bar 121 other than the support shafts at both ends in the longitudinal direction. 122 (foam rubber) is formed. When the pressure roller 111 has a large heat capacity and a high thermal conductivity, the surface of the fixing roller 110 is easily deprived of heat at the fixing nip portion N1. If the pressure roller 111 has a large heat capacity and high thermal conductivity, heat received from the surface of the fixing roller 110 at the fixing nip portion N1 is easily absorbed into the pressure roller 111. It becomes difficult for the surface temperature of the roller 111 to rise. That is, the pressure roller 111 has a low heat capacity, a low thermal conductivity, and a high heat insulating effect, so that the heat of the fixing roller 110 is less likely to be removed. Therefore, the rise time of the surface temperature of the fixing roller 110 can be shortened. The thermal conductivity of foamed rubber obtained by foaming the silicone rubber is 0.11 to 0.16 W / m · K, which is lower than that of solid rubber of about 0.25 to 0.29 W / m · K. The specific gravity related to the heat capacity is about 1.05 to 1.30 for solid rubber, and about 0.75 to 0.85 for foamed rubber, which is also a low heat capacity. Therefore, the rise time of the surface temperature of the fixing roller 110 can be shortened by using the foamed rubber as the elastic rubber layer 122 of the pressure roller 111. A release layer 123 made of PFA is provided on the outermost layer of the pressure roller 111. That is, a release layer 123 made of perfluoroalkoxy resin (PFA), which is a fluorine-based material, is formed on the outer side (on the outer peripheral surface) of the elastic rubber layer 122. The release layer 123 may be formed by coating the outer peripheral surface of the elastic rubber layer 122 with a tube, or coating the outer peripheral surface of the elastic rubber layer 122 with a paint. In Example 1, a tube having excellent durability was used as the release layer 123. As a material for the release layer 123, in addition to PFA, fluorine resin such as polytetrafluoroethylene resin (PTFE) and tetrafluoroethylene-hexafluoropropylene resin (FEP), fluorine rubber and silicone rubber having good release properties Etc. may be used. Further, the pressure roller 111 can obtain a predetermined width in the fixing nip portion N1 even if the pressure roller 111 is low in hardness, but if it is too low, the durability of the pressure roller 111 is deteriorated. For this reason, in Example 1, the hardness of the pressure roller 111 is 40 to 45 degrees in terms of Asker-C hardness (4.9 N load).

加熱フィルムの構成：加熱フィルム１２０は、ヒータ１１３の熱を受けるため耐熱性が必要であり、またヒータ１１３と接触しつつ移動するため強度も必要である。この加熱フィルム１２０は、可撓性及び耐熱性を有する無端状の薄いフィルムであって、無端状のフィルム基層（以下、基層と記す）１２６の外周面上に離型層１２７を形成したものである。基層１２６の材料として、ＳＵＳ（Ｓｔａｉｎｌｅｓｓ Ｕｓｅｄ Ｓｔｅｅｌ：ステンレス鋼）などの金属や、ポリイミドなどの耐熱性樹脂を用いると良い。金属は樹脂に比べると強度があるため薄肉化でき、また熱伝導率も高いため、ヒータ１１３の熱を定着ローラ１１０へ伝達しやすい。樹脂は金属に比べると比重が小さいため熱容量が小さく温まりやすい利点がある。また樹脂は塗工成型により薄肉のフィルムが成型できるため安価に成型できる。本実施例１では、基層１２６の材料として、ポリイミド樹脂にカーボン系の熱伝導フィラーを添加して熱伝導率を向上させたものを用いた。基層１２６の厚さは、薄いほどヒータ１１３の熱を定着ローラ１１０表面に伝達しやすいが、基層１２６の強度が低下するため、２０μｍ〜１００μｍ程度が好ましい。本実施例１では、基層１２６の厚さを６０μｍとした。基層１２６の外周面には、基層１２６の外周面の汚れを低減するためＰＦＡの離型層１２７が設けられている。離型層１２７の材料として、加圧ローラ１１１の離型層１２３と同様、ＰＦＡの他に、ＰＴＦＥ、ＦＥＰ等のフッ素樹脂を用いても良い。加熱フィルム１２０の離型層１２７の厚さは、薄いほどヒータ１１３の熱を定着ローラ１１０表面に伝達しやすいため、１μｍ〜２０μｍ程度が好ましい。本実施例１では、離型層１２７の厚さを１０μｍとした。   Structure of heating film: The heating film 120 needs heat resistance in order to receive the heat of the heater 113, and also needs strength because it moves in contact with the heater 113. The heating film 120 is an endless thin film having flexibility and heat resistance, and a release layer 127 is formed on the outer peripheral surface of an endless film base layer (hereinafter referred to as a base layer) 126. is there. As a material for the base layer 126, a metal such as SUS (Stainless Used Steel) or a heat resistant resin such as polyimide may be used. Since metal is stronger than resin, it can be thinned and has high thermal conductivity, so that heat from the heater 113 is easily transmitted to the fixing roller 110. Since resin has a lower specific gravity than metal, there is an advantage that the heat capacity is small and the resin is easily heated. In addition, the resin can be molded at low cost because a thin film can be formed by coating. In Example 1, as the material of the base layer 126, a material obtained by adding a carbon-based heat conductive filler to polyimide resin to improve the heat conductivity was used. The thinner the base layer 126 is, the easier it is to transfer the heat of the heater 113 to the surface of the fixing roller 110. However, since the strength of the base layer 126 is reduced, the thickness is preferably about 20 μm to 100 μm. In Example 1, the thickness of the base layer 126 was 60 μm. A PFA release layer 127 is provided on the outer peripheral surface of the base layer 126 in order to reduce contamination on the outer peripheral surface of the base layer 126. As a material for the release layer 127, as in the release layer 123 of the pressure roller 111, a fluororesin such as PTFE or FEP may be used in addition to PFA. The thickness of the release layer 127 of the heating film 120 is preferably about 1 μm to 20 μm because the heat from the heater 113 is more easily transmitted to the surface of the fixing roller 110 as the thickness becomes thinner. In Example 1, the thickness of the release layer 127 was 10 μm.

ヒータの構成：ヒータ１１３は、幅６ｍｍ、厚さ１ｍｍのアルミナ製の細長いヒータ基板１１３ａを有している（図１の（ｂ））。このヒータ基板１１３ａの表面（定着ローラ１１０側の面）には、ヒータ基板１１３ａの長手方向に沿ってＡｇ／Ｐｄ（銀パラジウム）の通電発熱抵抗層１１３ｂをスクリーン印刷により１０μｍ程度の厚さで線状又は幅の細い帯状に塗工して形成している。またヒータ基板１１３ａの表面には、通電発熱抵抗層１１３ｂに給電するための電極部（不図示）が形成してある。さらにヒータ基板１１３ａの表面には、通電発熱抵抗層１１３ｂを覆うように保護層としてのガラス層１１３ｃが５０μｍの厚さで形成されている。このヒータ１１３は、加熱フィルム１２０の内部に配設された細長いヒータホルダー１１９によってガラス層１１３ｃが加熱フィルム１２０の内周面すなわち基層１２６の内周面(内面）と対向するように支持されている。   Structure of heater: The heater 113 has an elongated heater substrate 113a made of alumina having a width of 6 mm and a thickness of 1 mm ((b) of FIG. 1). On the surface of the heater substrate 113a (the surface on the side of the fixing roller 110), an energization heating resistor layer 113b of Ag / Pd (silver palladium) is lined in a thickness of about 10 μm by screen printing along the longitudinal direction of the heater substrate 113a. It is formed by coating in the shape of a strip or a narrow strip. An electrode portion (not shown) for supplying power to the energization heating resistor layer 113b is formed on the surface of the heater substrate 113a. Further, a glass layer 113c as a protective layer is formed to a thickness of 50 μm on the surface of the heater substrate 113a so as to cover the energization heating resistor layer 113b. The heater 113 is supported by an elongated heater holder 119 disposed inside the heating film 120 so that the glass layer 113 c faces the inner peripheral surface of the heating film 120, that is, the inner peripheral surface (inner surface) of the base layer 126. .

定着ローラの構成：定着ローラ１１０は、細長い鉄製の芯金１１７を有し、この芯金１１７の長手方向両端部の支持軸部以外の外周面上に加圧ローラ１１１の弾性ゴム層１２２と同じ発泡ゴムの弾性ゴム層１１６を形成したものである。定着ローラ１１０は、弾性ゴム層１１６の熱容量が大きく、且つ、熱伝導率が高いと、加熱ニップ部Ｎ２でヒータ１１３から加熱フィルム１２０を介して定着ローラ表面が受ける熱が定着ローラ内部へ吸収され易く、定着ローラの表面温度が上昇しにくくなる。すなわち、弾性ゴム層１１６は、できるだけ低熱容量で、且つ、熱伝導率が低く、断熱効果の高い方が、定着ローラ１１０の表面温度の立ち上がり時間を短縮できる。弾性ゴム層１１６は、加圧ローラ１１１の弾性ゴム層１２２と同じであり、低熱容量（比重：約０．７５〜０．８５）で、且つ、熱伝導率が低い（熱伝導率：０．１１〜０．１６Ｗ／ｍ・Ｋ）単層の弾性ゴム層である。従って、この弾性ゴム層１１６を用いることによって定着ローラ１１０の表面温度の立ち上がり時間を短縮できる。定着ローラ１１０の外径は小さい方が熱容量を抑えられるが、小さ過ぎると加熱ニップ部Ｎ２及び定着ニップ部Ｎ１の幅が狭くなってしまうので適度な径が必要である。本実施例１では、定着ローラ１１０の外径をφ２０ｍｍとした。弾性ゴム層１１６の肉厚に関しても、薄過ぎれば金属製の芯金１１７に熱が逃げるので適度な厚みが必要である。本実施例１では、弾性ゴム層１１６の厚さを４ｍｍとした。そしてこの弾性ゴム層１１６の外側（外周面）には、フッ素系材料からなるＰＦＡの離型層１１８が形成されている。   Configuration of Fixing Roller: The fixing roller 110 has an elongated iron cored bar 117, and is the same as the elastic rubber layer 122 of the pressure roller 111 on the outer peripheral surface of the cored bar 117 other than the support shafts at both ends in the longitudinal direction. An elastic rubber layer 116 of foamed rubber is formed. When the heat capacity of the elastic rubber layer 116 is large and the heat conductivity is high, the fixing roller 110 absorbs the heat received by the surface of the fixing roller from the heater 113 through the heating film 120 in the heating nip portion N2. It is easy to increase the surface temperature of the fixing roller. That is, the elastic rubber layer 116 can shorten the rise time of the surface temperature of the fixing roller 110 when the heat capacity is as low as possible, the thermal conductivity is low, and the heat insulation effect is high. The elastic rubber layer 116 is the same as the elastic rubber layer 122 of the pressure roller 111, has a low heat capacity (specific gravity: about 0.75 to 0.85), and has a low thermal conductivity (thermal conductivity: 0. 0. 11 to 0.16 W / m · K) A single-layer elastic rubber layer. Therefore, the rise time of the surface temperature of the fixing roller 110 can be shortened by using the elastic rubber layer 116. If the outer diameter of the fixing roller 110 is smaller, the heat capacity can be suppressed. However, if the outer diameter is too small, the widths of the heating nip portion N2 and the fixing nip portion N1 are narrowed, and thus an appropriate diameter is required. In the first embodiment, the outer diameter of the fixing roller 110 is 20 mm. Regarding the thickness of the elastic rubber layer 116, if it is too thin, heat is released to the metal core 117, so that an appropriate thickness is required. In Example 1, the thickness of the elastic rubber layer 116 was 4 mm. A PFA release layer 118 made of a fluorine-based material is formed on the outer side (outer peripheral surface) of the elastic rubber layer 116.

定着ニップ部と加熱ニップ部の説明：定着ローラ１１０は、加圧ローラ１１１の芯金１１７の長手方向両端部の支持軸部が定着装置１００の装置フレーム（不図示）に軸受（不図示）を介して回転自在に支持されている。加圧ローラ１１１は、定着ローラ１１０の下方で定着ローラ１１０と並列に配設されている。そして加圧ローラ１１１の芯金１２１の長手方向両端部の支持軸部が装置フレームに軸受１２５を介して回転自在に支持されている。そしてこの軸受１２５を加圧バネ１２４により上方向Ａ２へ加圧し加圧ローラ１１１表面を定着ローラ１１０表面に接触させることによって、加圧ローラ１１１の弾性ゴム層１２２と定着ローラ１１０の弾性ゴム層１１６をそれぞれ弾性変形させている。これにより定着ローラ１１０表面と加圧ローラ１１１表面との間に所定幅の定着ニップ部Ｎ１を形成している。本実施例１では、加圧バネ１２４により軸受１２５を１４７Ｎの力で加圧することによって、幅７ｍｍの定着ニップ部Ｎ１を形成している。ヒータホルダー１１９は、ヒータホルダー１１９の長手方向両端部が装置フレームに上下動可能に支持されている。そしてヒータホルダー１１９の長手方向両端部を加圧バネ１１４で下方向Ａ１へ加圧しヒータ１１３のガラス層１１３ｃ表面を加熱フィルム１２０の基層１２６内面に接触させ加熱フィルム１２０表面を定着ローラ１１０表面に加圧状態に接触させている。これにより定着ローラ１１０の弾性ゴム層１１６を弾性変形させ、加熱フィルム１２０表面と定着ローラ１１０表面との間に所定幅の加熱ニップ部Ｎ２を形成している。本実施例１では、加圧バネ１１４によりヒータホルダー１１９の長手方向両端部を９８Ｎの力で加圧することによって、幅５．５ｍｍの加熱ニップ部Ｎ２を形成している。ヒータ１１３のガラス層１１３ｃの表面には、加熱フィルム１２０の基層１２６内面との摺動性を確保するために、潤滑剤として耐熱性のフッ素グリス（不図示）を塗付している。   Description of the fixing nip portion and the heating nip portion: In the fixing roller 110, support shaft portions at both longitudinal ends of the core metal 117 of the pressure roller 111 support bearings (not shown) on the device frame (not shown) of the fixing device 100. It is rotatably supported via. The pressure roller 111 is disposed below the fixing roller 110 and in parallel with the fixing roller 110. Support shafts at both ends in the longitudinal direction of the core metal 121 of the pressure roller 111 are rotatably supported by the apparatus frame via bearings 125. The bearing 125 is pressed in the upward direction A2 by the pressure spring 124, and the surface of the pressure roller 111 is brought into contact with the surface of the fixing roller 110, whereby the elastic rubber layer 122 of the pressure roller 111 and the elastic rubber layer 116 of the fixing roller 110 are contacted. Each is elastically deformed. Thus, a fixing nip portion N1 having a predetermined width is formed between the surface of the fixing roller 110 and the surface of the pressure roller 111. In the first embodiment, the fixing nip portion N1 having a width of 7 mm is formed by pressurizing the bearing 125 with a force of 147 N by the pressure spring 124. The heater holder 119 is supported by the apparatus frame so that the both ends in the longitudinal direction of the heater holder 119 can move up and down. Then, both end portions of the heater holder 119 in the longitudinal direction are pressed downward by the pressure springs 114 so that the surface of the glass layer 113c of the heater 113 is brought into contact with the inner surface of the base layer 126 of the heating film 120 and the surface of the heating film 120 is added to the surface of the fixing roller 110. In contact with pressure. As a result, the elastic rubber layer 116 of the fixing roller 110 is elastically deformed, and a heating nip portion N2 having a predetermined width is formed between the surface of the heating film 120 and the surface of the fixing roller 110. In the first embodiment, the heating nip portion N2 having a width of 5.5 mm is formed by pressing both ends in the longitudinal direction of the heater holder 119 with a force of 98 N by the pressing spring 114. A heat-resistant fluorine grease (not shown) is applied as a lubricant to the surface of the glass layer 113c of the heater 113 in order to ensure slidability with the inner surface of the base layer 126 of the heating film 120.

定着装置の加熱定着動作：プリント信号に応じて定着モータＭ(図１の（ａ））が回転駆動し定着ローラ１１０を矢印方向へ周速度６０ｍｍ／ｓｅｃ（プロセススピード）で回転させる。この定着ローラ１１０の回転は定着ニップ部Ｎ１を通じて加圧ローラ１１１表面に伝達される。これにより加圧ローラ１１１は定着ローラ１１０の回転に追従して矢印方向へ回転する。また定着ローラ１１０の回転は加熱ニップ部Ｎ２を通じて加熱フィルム１２０表面に伝達される。これにより加熱フィルム１２０は基層１２６内面がヒータ１１３のガラス層１１３ｃ表面と接触した状態で定着ローラ１１０の回転に追従して矢印方向へ回転する。またプリント信号に応じて温度制御部（不図示）がヒータ１１３の電極部を通じて通電発熱抵抗層１１３ｂに通電する。この通電により通電発熱抵抗層１１３ｂが発熱しヒータ１１３は急速に昇温し加熱フィルム１２０を加熱する。ヒータ１１３により加熱された加熱フィルム１２０は矢印方向へ回転しつつ加熱ニップ部Ｎ２で定着ローラ１１０表面を加熱する。ヒータ１１３の温度はヒータ基板１１３ａの裏面（定着ローラ１１０と反対側の面）に設けられたサーミスタなどの温度検知素子１１５により検知される。温度制御部は、温度検知素子１１５からの出力信号（温度検知信号）を取り込み、この出力信号に基づいてヒータ１１３が所定の定着温度（目標温度）を維持するように通電発熱抵抗層１１３ｂへの通電量を制御する。定着モータＭを回転駆動し、ヒータ１１３の通電発熱抵抗層１１３ｂに通電した状態で、未定着のトナー像ｔを担持した記録材Ｐがトナー像担持面を上向きして定着ニップ部Ｎ１に導入される。この記録材Ｐは定着ニップ部Ｎ１において定着ローラ１１０表面と加圧ローラ１１１表面とにより挟持搬送される。そしてこの搬送過程においてトナー像ｔに定着ローラ１１０の熱と定着ニップ部Ｎ１の圧力が付与され、この熱と圧力によってトナー像ｔは記録材Ｐ上に加熱定着される。   Heating and fixing operation of the fixing device: The fixing motor M ((a) in FIG. 1) is driven to rotate in accordance with a print signal to rotate the fixing roller 110 in the arrow direction at a peripheral speed of 60 mm / sec (process speed). The rotation of the fixing roller 110 is transmitted to the surface of the pressure roller 111 through the fixing nip portion N1. As a result, the pressure roller 111 rotates in the direction of the arrow following the rotation of the fixing roller 110. The rotation of the fixing roller 110 is transmitted to the surface of the heating film 120 through the heating nip portion N2. As a result, the heating film 120 rotates in the direction of the arrow following the rotation of the fixing roller 110 with the inner surface of the base layer 126 in contact with the surface of the glass layer 113c of the heater 113. Further, a temperature control unit (not shown) energizes the energization heating resistor layer 113b through the electrode unit of the heater 113 in accordance with the print signal. With this energization, the energization heat generating resistance layer 113b generates heat, and the heater 113 rapidly rises in temperature to heat the heating film 120. The heating film 120 heated by the heater 113 heats the surface of the fixing roller 110 at the heating nip portion N2 while rotating in the arrow direction. The temperature of the heater 113 is detected by a temperature detection element 115 such as a thermistor provided on the back surface (the surface opposite to the fixing roller 110) of the heater substrate 113a. The temperature control unit takes in an output signal (temperature detection signal) from the temperature detection element 115, and based on this output signal, the heater 113 is supplied to the energization heating resistor layer 113b so as to maintain a predetermined fixing temperature (target temperature). Control the energization amount. The recording material P carrying the unfixed toner image t is introduced into the fixing nip portion N1 with the toner image carrying surface facing upward in a state where the fixing motor M is driven to rotate and the energization heat generation resistance layer 113b of the heater 113 is energized. The The recording material P is nipped and conveyed by the surface of the fixing roller 110 and the surface of the pressure roller 111 at the fixing nip portion N1. In this conveying process, the heat of the fixing roller 110 and the pressure of the fixing nip portion N1 are applied to the toner image t, and the toner image t is heated and fixed on the recording material P by the heat and pressure.

定着ローラ表面から加熱フィルム表面への異物の転移メカニズム：定着ローラ表面のマイクロ硬度が高い構成の従来の定着ローラを用いると、加熱フィルム表面に紙粉やトナーなどの異物が加熱フィルム表面に付着しやすい。ここで、本実施例１の定着ローラ１１０と区別するため、従来の定着ローラの符号を１１０Ａとする。従来の定着ローラ１１０Ａを用いた定着装置において、上述のように記録材Ｐ上へのトナー像ｔの加熱定着が繰り返されると、定着ローラ１１０Ａ表面に付着した紙粉やトナーなどの異物が加熱フィルム１２０表面に転移する。すなわち、定着ニップ部Ｎ１で定着ローラ１１０Ａ表面が記録材Ｐ上のトナー像ｔと接触するため、微量の紙粉やトナーなどの異物が定着ローラ１１０Ａ表面に付着する。定着ローラ１１０Ａ表面に異物が付着すると、加熱フィルム１２０が定着ローラ１１０Ａ表面と接触し回転しているため、定着ローラ１１０Ａ表面に付着した異物は加熱フィルム１２０表面に付着し転移してしまう。加熱フィルム１２０表面に異物が付着すると、ヒータ１１３の熱が定着ローラ１１０Ａ表面に伝わりにくくなり、記録材Ｐ上のトナー像ｔの溶融不足で記録材Ｐ上へのトナー像ｔの定着性が悪化し定着不良が発生することがある。また加熱フィルム１２０表面に異物が付着すると、加熱ニップ部Ｎ２で加熱フィルム１２０表面から定着ローラ１１０Ａ表面に異物が吐き出され、この異物が定着ニップ部Ｎ１で記録材Ｐに転移し記録材Ｐの画像印字面を汚したりする画像不良が発生する。従来の定着ローラ１１０Ａ表面から加熱フィルム１２０表面に異物が転移するメカニズムを図２の（ｂ）を参照して説明する。例えば紙粉などの異物Ｙ１が定着ローラ１１０Ａ表面（離型層１１８）に付着し加熱ニップ部Ｎ２に到達する。すると、定着ローラ表面１１０Ａはマイクロ硬度が高いため、加熱ニップ部Ｎ２内で異物Ｙ１は加熱フィルム１１０Ａ側に加圧され加熱フィルム１１０Ａ表面（離型層１２７）に押し付けられる。加熱フィルム１２０は内側から剛性の高いヒータ１１３により押圧されているため、定着ローラ１１０Ａにより押し付けられた異物Ｙ１を加熱フィルム１２０表面で吸収することはできない。このため、図２の（ｂ）に示すように、異物Ｙ１は加熱フィルム１２０の離型層１２７にめり込んでしまう。この加熱フィルム１２０の離型層１２７への異物Ｙ１のめり込みが繰り返されると、加熱フィルム１２０表面に異物Ｙ１が蓄積してしまう。加熱ニップ部Ｎ２に記録材などを通過させれば、加熱フィルム１２０表面に蓄積した異物Ｙ１は、加熱フィルム１２０より温度の低い記録材側へ転移し、加熱フィルム１２０表面から異物Ｙ１を除去することができる。しかし、加熱ニップ部Ｎ２に記録材などは通過されないため、加熱フィルム１２０表面に一度異物Ｙ１が付着すると除去することが困難であり、異物Ｙ１は加熱フィルム１２０表面に蓄積していく。   Transfer mechanism of foreign matter from the surface of the fixing roller to the surface of the heating film: When using a conventional fixing roller with a high micro hardness on the surface of the fixing roller, foreign matters such as paper dust and toner adhere to the surface of the heating film. Cheap. Here, in order to distinguish from the fixing roller 110 of the first embodiment, the reference numeral 110A of the conventional fixing roller is assumed. In the fixing device using the conventional fixing roller 110A, when the heat fixing of the toner image t on the recording material P is repeated as described above, foreign matters such as paper dust and toner adhering to the surface of the fixing roller 110A are heated. 120 Transfer to surface. That is, since the surface of the fixing roller 110A comes into contact with the toner image t on the recording material P at the fixing nip portion N1, a small amount of foreign matters such as paper dust and toner adhere to the surface of the fixing roller 110A. When the foreign matter adheres to the surface of the fixing roller 110A, the heating film 120 contacts and rotates with the surface of the fixing roller 110A, so that the foreign matter attached to the surface of the fixing roller 110A adheres to the surface of the heating film 120 and is transferred. If foreign matter adheres to the surface of the heating film 120, it becomes difficult for the heat of the heater 113 to be transmitted to the surface of the fixing roller 110A, and the fixing of the toner image t onto the recording material P deteriorates due to insufficient melting of the toner image t on the recording material P. Fixing failure may occur. Further, when foreign matter adheres to the surface of the heating film 120, the foreign matter is discharged from the surface of the heating film 120 to the surface of the fixing roller 110A at the heating nip portion N2, and the foreign matter is transferred to the recording material P at the fixing nip portion N1. An image defect that causes the printed surface to become dirty occurs. A mechanism for transferring foreign matter from the surface of the conventional fixing roller 110A to the surface of the heating film 120 will be described with reference to FIG. For example, foreign matter Y1 such as paper dust adheres to the surface of the fixing roller 110A (release layer 118) and reaches the heating nip portion N2. Then, since the fixing roller surface 110A has a high micro hardness, the foreign matter Y1 is pressed toward the heating film 110A in the heating nip portion N2 and pressed against the surface of the heating film 110A (release layer 127). Since the heating film 120 is pressed from the inside by the highly rigid heater 113, the surface of the heating film 120 cannot absorb the foreign matter Y1 pressed by the fixing roller 110A. For this reason, as shown in FIG. 2B, the foreign matter Y <b> 1 sinks into the release layer 127 of the heating film 120. When the penetration of the foreign matter Y1 into the release layer 127 of the heating film 120 is repeated, the foreign matter Y1 accumulates on the surface of the heating film 120. If a recording material or the like is passed through the heating nip portion N2, the foreign matter Y1 accumulated on the surface of the heating film 120 is transferred to the recording material side having a lower temperature than the heating film 120, and the foreign matter Y1 is removed from the surface of the heating film 120. Can do. However, since the recording material or the like does not pass through the heating nip N2, it is difficult to remove the foreign matter Y1 once attached to the surface of the heating film 120, and the foreign matter Y1 accumulates on the surface of the heating film 120.

本実施例１では、定着ローラ１１０表面の微小硬度（マイクロ硬度）を低くすることで、定着ローラ１１０表面から加熱フィルム１２０表面への異物の転移を低減している。本実施例１の定着ローラ１１０を用いた場合の定着ローラ１１０表面から加熱フィルム１２０表面への異物の転移を低減できるメカニズムを図２の（ａ）を参照して説明する。例えば紙粉などの異物Ｙ１が定着ローラ１１０表面（離型層１１８）に付着し加熱ニップ部Ｎ２に到達すると、定着ローラ１１０表面はマイクロ硬度が低いため、加熱ニップ部Ｎ２内で異物Ｙ１は定着ローラ表面１１０に包み込まれる。異物Ｙ１は定着ローラ１１０表面に包み込まれると加熱フィルム１２０側への押し付けが弱くなり、加熱フィルム１２０表面に付着せずに定着ローラ１１０表面に付着したまま加熱ニップ部Ｎ２を通過する。加熱ニップ部Ｎ２を通過した定着ローラ１１０表面上の異物Ｙ１は、定着ニップ部Ｎ１を通過する記録材Ｐに転移するため、定着ローラ１１０表面上に異物Ｙ１が蓄積することは無い。また記録材Ｐが通過する度に、定着ローラ１１０表面上の異物Ｙ１は記録材Ｐ上へ転移するため、記録材Ｐ上へ転移した異物Ｙ１の量は少なく、定着ローラ１１０表面上の異物Ｙ１を目立たずに記録材Ｐ上へ排出することができる。このように定着ローラ１１０表面のマイクロ硬度が低いと、加熱フィルム１２０表面には異物Ｙ１が付着しにくく、且つ、記録材Ｐ上へ目立たずに異物Ｙ１を排出することができる。   In the first embodiment, the transfer of foreign matter from the surface of the fixing roller 110 to the surface of the heating film 120 is reduced by reducing the micro hardness (micro hardness) of the surface of the fixing roller 110. A mechanism capable of reducing the transfer of foreign matter from the surface of the fixing roller 110 to the surface of the heating film 120 when the fixing roller 110 of the first embodiment is used will be described with reference to FIG. For example, when foreign matter Y1 such as paper dust adheres to the surface of the fixing roller 110 (release layer 118) and reaches the heating nip portion N2, the surface of the fixing roller 110 has a low micro hardness, so the foreign matter Y1 is fixed in the heating nip portion N2. Wrapped in the roller surface 110. When the foreign matter Y1 is encased in the surface of the fixing roller 110, the pressing toward the heating film 120 becomes weak, and the foreign matter Y1 passes through the heating nip portion N2 while adhering to the surface of the fixing roller 110 without adhering to the surface of the heating film 120. The foreign matter Y1 on the surface of the fixing roller 110 that has passed through the heating nip portion N2 is transferred to the recording material P that passes through the fixing nip portion N1, so that the foreign matter Y1 does not accumulate on the surface of the fixing roller 110. Further, every time the recording material P passes, the foreign matter Y1 on the surface of the fixing roller 110 is transferred onto the recording material P. Therefore, the amount of the foreign matter Y1 transferred onto the recording material P is small and the foreign matter Y1 on the surface of the fixing roller 110 is small. Can be discharged onto the recording material P without conspicuous. Thus, when the micro hardness of the surface of the fixing roller 110 is low, the foreign matter Y1 is difficult to adhere to the surface of the heating film 120, and the foreign matter Y1 can be discharged without being noticeable on the recording material P.

加熱フィルム表面の付着異物による汚れと定着ローラ表面のマイクロ硬度との関係：加熱フィルム表面に付着した異物量（以下、汚れ量とも記す）が定着ローラ表面のマイクロ硬度に関係していることが以下の実験で分かった。定着ローラの弾性ゴム層（発泡ゴム）のゴム厚みと、ゴム材料（厚さ１０ｍｍの試験片のＡｓｋｅｒ−Ｃゴム硬度違い）と、ＰＦＡ離型層の厚みと、をそれぞれ変えて、１１種類の実験用定着ローラ（表１参照）を作製した。そしてこの１１種類の定着ローラについて、定着ローラ表面のマイクロ硬度及びＡｓｋｅｒ−Ｃ硬度を測定した。定着ローラ表面のマイクロ硬度は、高分子計器株式会社製のマイクロゴム硬度計（ＭＤ−１）、押針形状はタイプＡ（高さ０．５０ｍｍ、φ０．１６ｍｍの円柱形）を用いて測定した。定着ローラ表面のＡｓｋｅｒ−Ｃ硬度は、高分子計器株式会社製のＡｓｋｅｒゴム硬度計、押針形状はタイプＣ（高さ２．５４ｍｍ、φ５．０８ｍｍの半球）を用い４．９Ｎ荷重で測定した。また各定着ローラを用いて１０００枚の通紙耐久（定着装置の耐久寿命の１／５０）を行い加熱フィルム表面の汚れ量の比較を行った。記録材としては、汚れ（紙粉）が発生しやすいように炭酸カルシウム１５Ｗｔ％を含む紙を用いた。記録材に印字する印字パターンは、イエロー、マゼンダ、シアン、ブラックの各色２％印字率のハーフトーン画像である。印字耐久後の加熱フィルム表面の汚れを透明な粘着テープで加熱フィルム表面から剥がし、この粘着テープで剥がした汚れを光学式濃度計により濃度測定を行うことで加熱フィルム表面の汚れ量（加熱フィルム表面の汚れ濃度）を定量化し比較した。結果を表１に示す。光学式濃度計として、マクベス反射濃度計ＲＤ９１４を用いている。   Relationship between contamination due to foreign matter adhering to heating film surface and micro hardness of fixing roller surface: The amount of foreign matter adhering to the heating film surface (hereinafter also referred to as contamination amount) is related to the micro hardness of fixing roller surface. It was found in the experiment. By changing the rubber thickness of the elastic rubber layer (foam rubber) of the fixing roller, the rubber material (difference in Asker-C rubber hardness of the test piece having a thickness of 10 mm), and the thickness of the PFA release layer, respectively, An experimental fixing roller (see Table 1) was prepared. And about these 11 types of fixing rollers, the micro hardness and Asker-C hardness of the surface of the fixing roller were measured. The micro hardness of the surface of the fixing roller was measured using a micro rubber hardness meter (MD-1) manufactured by Kobunshi Keiki Co., Ltd., and the shape of the push needle was measured using Type A (cylindrical shape having a height of 0.50 mm and φ0.16 mm). . The Asker-C hardness of the surface of the fixing roller was measured with a load of 4.9 N using an Asker rubber hardness meter manufactured by Kobunshi Keiki Co., Ltd., and the shape of the pusher needle was type C (hemisphere with a height of 2.54 mm and φ5.08 mm). . Further, 1000 sheets were passed through each fixing roller (1/50 of the durability of the fixing device) and the amount of dirt on the surface of the heating film was compared. As the recording material, paper containing 15 Wt% of calcium carbonate was used so that dirt (paper dust) was easily generated. The print pattern to be printed on the recording material is a halftone image having a printing rate of 2% for each color of yellow, magenta, cyan, and black. The dirt on the surface of the heated film is peeled off from the surface of the heated film with a transparent adhesive tape, and the amount of dirt on the surface of the heated film is measured by measuring the density with an optical densitometer. ) Was quantified and compared. The results are shown in Table 1. As an optical densitometer, Macbeth reflection densitometer RD914 is used.

表１に示すように、（ｉ）弾性ゴム層の厚み違いでは、ゴムの厚みが厚くなるほど定着ローラのＡｓｋｅｒ−Ｃ硬度は低くなるが、マイクロ硬度には変化が無く、加熱フィルム表面の汚れ濃度も変わらない結果であった。すなわち、加熱フィルム表面の汚れと定着ローラのＡｓｋｅｒ−Ｃ硬度は関係が無いことが分かった。次に、（ｉｉ）弾性ゴム材料硬度違いでは、ゴム材料硬度（試験片Ａｓｋｅｒ−Ｃ硬度）が高くなるほど定着ローラのＡｓｋｅｒ−Ｃ硬度とマイクロ硬度が高くなり、加熱フィルム表面の汚れ濃度が濃くなる結果であった。（ｉ）と（ｉｉ）の結果より、定着ローラ表面のマイクロ硬度が低いと加熱フィルム表面が汚れにくいことが分かった。次に、（ｉｉｉ）離型層の厚み違いでは、離型層が厚くなるほど定着ローラ表面のマイクロ硬度が高くなり、加熱フィルム表面の汚れ濃度が濃くなる結果であった。すなわち、離型層を薄くするほど定着ローラ表面のマイクロ硬度が低くなり、加熱フィルム表面の汚れを抑えることができることが分かった。 As shown in Table 1, (i) With the difference in thickness of the elastic rubber layer, the Asker-C hardness of the fixing roller decreases as the rubber thickness increases, but the micro hardness does not change, and the dirt density on the surface of the heating film The result was unchanged. That is, it was found that there was no relationship between the dirt on the heated film surface and the Asker-C hardness of the fixing roller. Next, (ii) with respect to the hardness of the elastic rubber material, the higher the rubber material hardness (test piece Asker-C hardness), the higher the Asker-C hardness and the micro hardness of the fixing roller, and the higher the dirt density on the surface of the heating film. It was a result. From the results of (i) and (ii), it was found that when the micro hardness of the surface of the fixing roller is low, the surface of the heating film is hardly soiled. Next, (iii) the difference in the thickness of the release layer resulted in that the thicker the release layer, the higher the micro hardness on the surface of the fixing roller, and the higher the dirt density on the surface of the heating film. That is, it was found that the thinner the release layer, the lower the micro hardness of the surface of the fixing roller, and the contamination of the surface of the heating film can be suppressed.

マイクロ硬度と異物包み込み性との関係：定着ローラ表面のマイクロ硬度と定着ローラ表面の異物の包み込み性との関係を調査した。調査方法を以下に説明する。図３の（ａ）と（ｂ）は定着ローラ表面のマイクロ硬度と定着ローラ表面の異物の包み込み性との関係を調査する方法の説明図である。図３の（ａ）はその調査に用いられる定着ローラ、ガラスプレート、ガラスビーズ及び光学顕微鏡の関係を表わす外観斜視図である。（ｂ）は定着ローラとガラスプレートとの間のガラスビーズをガラスプレート上方から光学顕微鏡で観察するときの定着ローラ、ガラスプレート及びガラスビーズの関係を表わす断面図である。まず、図３の（ａ）に示すように、異物に見立てたφ１２０μｍのガラスビーズＧｂを定着ローラ１１０表面上に置き、このガラスビーズＧｂを透明なガラスプレートＧｐで定着ローラ１１０表面に加圧してニップ部Ｎａを形成する。次に、図３の（ｂ）に示すように、ガラスプレートＧｐ上方からガラスビーズＧｂを光学顕微鏡Ｋで観察した。すると、ガラスビーズＧｂにより、定着ローラ１１０表面がガラスプレートＧｐと密着していない部分ができた。この密着していない部分の直径Ｘを光学顕微鏡Ｋにより測定し、マイクロ硬度とガラスビーズＧｂの密着性（包み込み性）の関係を調査した。調査は表１の（ｉｉｉ）の離型層の厚み違いによるマイクロ硬度違い（４水準）について行った。結果を図３の（ｃ）に示す。定着ローラ１１０表面のマイクロ硬度が低いほど、定着ローラ１１０表面がガラスプレートＧｐと密着していない直径Ｘが小さくなり、ガラスビーズＧｂを包み込んでいることが分かった。すなわち、定着ローラ１１０表面のマイクロ硬度が低いほど加熱ニップ部Ｎ２で異物Ｙ１が定着ローラ１１０表面に包み込まれやすいことが分かった。加熱ニップ部Ｎ２内で異物Ｙ１が定着ローラ１１０表面に包み込まれると、図２の（ａ）に示すように異物Ｙ１を加熱フィルム１２０表面に押し付けにくくなるため、異物Ｙ１は加熱フィルム１２０表面に付着しにくい。すなわち、定着ローラ１１０表面のマイクロ硬度が低いほど加熱フィルム１２０表面を汚しにくいということが分かった。   Relationship between micro hardness and foreign matter wrapping property: The relationship between the micro hardness of the fixing roller surface and the foreign matter wrapping property on the fixing roller surface was investigated. The investigation method is described below. FIGS. 3A and 3B are explanatory diagrams of a method for investigating the relationship between the micro hardness of the surface of the fixing roller and the wrapping property of foreign matter on the surface of the fixing roller. FIG. 3A is an external perspective view showing the relationship among the fixing roller, the glass plate, the glass beads, and the optical microscope used for the investigation. (B) is a cross-sectional view showing the relationship between the fixing roller, the glass plate, and the glass beads when the glass beads between the fixing roller and the glass plate are observed with an optical microscope from above the glass plate. First, as shown in FIG. 3A, a glass bead Gb having a diameter of 120 μm that is regarded as a foreign substance is placed on the surface of the fixing roller 110, and this glass bead Gb is pressed against the surface of the fixing roller 110 with a transparent glass plate Gp. The nip portion Na is formed. Next, the glass beads Gb were observed with the optical microscope K from above the glass plate Gp, as shown in FIG. Then, a portion where the surface of the fixing roller 110 was not in close contact with the glass plate Gp was formed by the glass beads Gb. The diameter X of the non-adhered part was measured with an optical microscope K, and the relationship between the micro hardness and the adhesiveness (enveloping property) of the glass beads Gb was investigated. The investigation was conducted for micro hardness differences (4 levels) due to thickness differences of the release layer in (iii) of Table 1. The results are shown in FIG. It was found that the lower the micro hardness of the surface of the fixing roller 110, the smaller the diameter X of the surface of the fixing roller 110 that is not in close contact with the glass plate Gp, which encloses the glass beads Gb. That is, it was found that the lower the micro hardness of the surface of the fixing roller 110, the more easily the foreign matter Y1 is wrapped in the surface of the fixing roller 110 at the heating nip portion N2. When the foreign matter Y1 is encased in the surface of the fixing roller 110 in the heating nip portion N2, it is difficult to press the foreign matter Y1 against the surface of the heating film 120 as shown in FIG. Hard to do. That is, it has been found that the lower the micro hardness of the surface of the fixing roller 110, the less likely the surface of the heating film 120 is soiled.

マイクロ硬度と画像不良との関係：上記の包み込み性の調査を行った定着ローラ（４水準）を用いた定着装置について、定着装置の耐久寿命の２倍である１０万枚まで印字耐久を行い、加熱フィルム表面の汚れの確認を調査した。また加熱フィルム表面の汚れによる定着不良及び汚れの吐き出しによる画像不良の発生の有無を調査した。トナー像の定着性は濃度低下率で表し、以下の方法で算出する。測定器はマクベス反射濃度計ＲＤ９１４を用い、紙上に定着されたハーフトーン画像を、シルボン紙を５枚重ねたところに荷重０．４Ｎ／ｃｍ２で５往復擦った前後の濃度を測定する。本実施例１では、ハーフトーン濃度として、擦る前の濃度Ｄ１が約０．７のものを用いた。擦った後の濃度をＤ２とすると、濃度低下率は（Ｄ１−Ｄ２）／Ｄ１により算出される。印字耐久５０００枚、１万枚、２．５万枚、５万枚、７．５万枚、１０万枚の各時点でブラック単色のハーフトーン画像を印字し、上記濃度低下率の測定を行い、定着性の評価を行った。濃度低下率が１０％未満の場合を良好な定着性として○と評価し、１０％以上２０％未満の場合を定着性の低下として△と評価し、濃度低下率が２０％以上のものを定着不良として×と評価した。また、定着性の判断基準は装置の仕様によるものであり、必要とされる定着性は装置によって適宜決めることができる。加熱フィルム表面の汚れの吐き出しによる画像不良は、汚れの吐き出しによる画像不良が無かった場合を○、画像不良が発生した場合を○として評価した。結果を表２に示す。 Relationship between micro hardness and image defect: For the fixing device using the fixing roller (4 levels) for which the above wrapping property investigation was performed, printing durability was performed up to 100,000 sheets, which is twice the durable life of the fixing device, The confirmation of the contamination of the heated film surface was investigated. In addition, the occurrence of defective fixing due to dirt on the surface of the heated film and the occurrence of defective images due to the discharge of dirt were investigated. The fixability of the toner image is represented by a density reduction rate and is calculated by the following method. The measuring instrument uses a Macbeth reflection densitometer RD914 to measure the density before and after rubbing 5 half-tone images fixed on the paper 5 times with a load of 0.4 N / cm 2 on 5 sheets of Sylbon paper. In Example 1, a halftone density having a density D1 before rubbing of about 0.7 was used. If the density after rubbing is D2, the density reduction rate is calculated by (D1-D2) / D1. Printing durability 5,000 sheets, 10,000 sheets, 25,000 sheets, 50,000 sheets, 75,000 sheets, 100,000 sheets, black halftone images are printed at each time point, and the density reduction rate is measured. The fixability was evaluated. When the density reduction rate is less than 10%, it is evaluated as “good” as good fixing property, and when it is 10% or more and less than 20%, it is evaluated as “△” as fixing property deterioration. It evaluated as x as a defect. Further, the fixing criteria are determined by the specifications of the apparatus, and the required fixing ability can be appropriately determined depending on the apparatus. The image defect due to the discharge of dirt on the surface of the heated film was evaluated as “◯” when there was no image defect due to the discharge of dirt, and “◯” when the image defect occurred. The results are shown in Table 2.

表２に示すように、離型層の厚みが１０μｍ、マイクロ硬度が３６度の定着ローラは、定着装置の耐久寿命の２倍である１０万枚まで定着不良及び汚れの吐き出しによる画像不良の発生は無かった。また離型層の厚みが２０μｍ、マイクロ硬度が４３度の定着ローラも、定着装置の耐久寿命の２倍である１０万枚まで定着不良及び汚れの吐き出しによる画像不良の発生は無かった。離型層の厚みが３０μｍ、マイクロ硬度が４９度の定着ローラは、１０万枚時点で定着性の低下は見られたものの、画像不良の発生は無かった。離型層の厚みが４０μｍ、マイクロ硬度が５７度の定着ローラは、定着装置の耐久寿命である５万枚から定着性の低下が見られ、７．５万枚以上で定着不良が発生し、１０万枚時点で画像不良も発生してしまった。定着ローラ表面のマイクロ硬度は低いほど定着不良や汚れの吐き出しによる画像不良が発生しにくい。少なくともマイクロ硬度が４９度以下であり、離型層の厚みが３０μｍであれば、定着不良及び画像不良の発生は無く、十分な加熱フィルム表面の汚れ低減効果が得られることがわかった。 As shown in Table 2, with a fixing roller having a release layer thickness of 10 μm and a micro hardness of 36 degrees, up to 100,000 sheets, which is twice the durable life of the fixing device, causes defective fixing and image defects due to discharge of dirt. There was no. Further, even with a fixing roller having a release layer thickness of 20 μm and a micro hardness of 43 degrees, there was no occurrence of defective images due to defective fixing and discharge of dirt up to 100,000 sheets, which is twice the durable life of the fixing device. In the fixing roller having a release layer thickness of 30 μm and a micro hardness of 49 degrees, although the fixing property was lowered at the time of 100,000 sheets, no image defect occurred. The fixing roller having a release layer thickness of 40 μm and a micro hardness of 57 degrees shows a decrease in fixing performance from the 50,000 sheets, which is the durable life of the fixing device, and a fixing defect occurs at 75,000 sheets or more. Image defects also occurred at the time of 100,000 sheets. The lower the microhardness of the surface of the fixing roller, the less likely to cause fixing defects and image defects due to dirt discharge. It was found that when the micro hardness is at least 49 degrees and the thickness of the release layer is 30 μm, there is no occurrence of fixing failure and image failure, and a sufficient dirt reduction effect on the heated film surface can be obtained.

弾性ゴム層の硬度とマイクロ硬度の説明：本実施例１では、表１に示す調査結果に基づき、加熱フィルム１２０表面の汚れすなわち加熱フィルム１２０表面への異物の付着を低減するために、定着ローラ１１０表面のマイクロ硬度ＨμをＨμ≦４９としている。上述のように弾性ゴム材料のゴム硬度を低くした方が定着ローラ１１０表面のマイクロ硬度は低くなるが、弾性ゴム材料のゴム硬度が低すぎると耐久性が低下する。このため、本実施例１では、定着ローラ１１０の弾性ゴム層１１６のゴム材料として、ゴム硬度（ゴム試験片Ａｓｋｅｒ−Ｃ硬度）が２０度のゴム材料を用いた。定着ローラ１１０の離型層１１８は薄くするほど定着ローラ１１０表面のマイクロ硬度を低くすることができるが、薄すぎると耐久性が低下するため１μｍ以上３０μｍ以下が好ましい。本実施例１では、離型層１１８として、厚さ１５μｍのＰＦＡチューブを用いた。本実施例１の定着ローラ１１０表面のマイクロ硬度を測定すると３１度であった。本実施例１の定着ローラ１１０においても、表２と同様の通紙耐久試験を行った。定着ローラ１１０は、定着ローラ表面のマイクロ硬度が低い（４９度以下）ため、加熱フィルム１２０表面の汚れを抑えることができ、定着装置の耐久寿命の２倍である１０万枚まで定着不良及び汚れの吐き出しによる画像不良の発生は無かった。   Description of Hardness and Microhardness of Elastic Rubber Layer: In Example 1, in order to reduce dirt on the surface of the heating film 120, that is, adhesion of foreign matters to the surface of the heating film 120, based on the investigation results shown in Table 1, a fixing roller The micro hardness Hμ of the surface 110 is set to Hμ ≦ 49. As described above, when the rubber hardness of the elastic rubber material is lowered, the micro hardness of the surface of the fixing roller 110 is lowered. However, if the rubber hardness of the elastic rubber material is too low, the durability is lowered. Therefore, in the first embodiment, a rubber material having a rubber hardness (rubber test piece Asker-C hardness) of 20 degrees is used as the rubber material of the elastic rubber layer 116 of the fixing roller 110. The thinner the release layer 118 of the fixing roller 110 is, the lower the micro hardness of the surface of the fixing roller 110 can be. However, if the thickness is too thin, the durability is lowered. In Example 1, a PFA tube having a thickness of 15 μm was used as the release layer 118. The micro hardness of the surface of the fixing roller 110 of Example 1 was measured to be 31 degrees. Also for the fixing roller 110 of the first embodiment, the same paper passing durability test as in Table 2 was performed. Since the fixing roller 110 has a low micro hardness (49 degrees or less) on the surface of the fixing roller, the surface of the heating film 120 can be prevented from being contaminated, and the fixing failure and contamination can be increased up to 100,000 sheets, which is twice the durable life of the fixing device. There was no occurrence of image defects due to the discharge of.

本実施例１の定着装置１００によれば、定着ローラ１１０表面のマイクロ硬度を５０度未満と低くすることで、加熱ニップ部Ｎ２において異物Ｙ１を定着ローラ１１０表面で包み込むことができる。これにより加熱フィルム１２０表面への異物Ｙ１の押し付けが緩和され、加熱フィルム１２０表面の異物Ｙ１の付着を低減できる。このため加熱フィルム１２０表面への異物Ｙ１の付着による定着不良、及び加熱フィルム１２０表面からの異物Ｙ１の吐き出しによる画像不良の発生を抑制することができる。   According to the fixing device 100 of the first embodiment, the foreign matter Y1 can be wrapped around the surface of the fixing roller 110 in the heating nip portion N2 by reducing the micro hardness of the surface of the fixing roller 110 to less than 50 degrees. Thereby, the pressing of the foreign matter Y1 on the surface of the heating film 120 is eased, and the adhesion of the foreign matter Y1 on the surface of the heating film 120 can be reduced. For this reason, it is possible to suppress the occurrence of fixing failure due to adhesion of the foreign matter Y1 to the surface of the heating film 120 and image failure due to ejection of the foreign matter Y1 from the surface of the heating film 120.

［実施例２］定着装置の他の例を説明する。本実施例２に示す定着装置は、定着ローラを後述のように構成した点を除いて、実施例１の定着装置と同じ構成としてある。本実施例２では、実施例１の定着装置と同じ部材・部分については、同一の符号で示し再度の説明を省略する。本実施例２の定着装置１００は、定着ローラ１３０として定着ローラの半径方向に異なる材料の複数のゴム層を有する定着ローラを用いている。そしてこの定着ローラ１３０表面のマイクロ硬度を低くすることで加熱フィルム１２０表面の汚れを低減することを特徴としている。   [Embodiment 2] Another example of the fixing device will be described. The fixing device shown in the second embodiment has the same configuration as the fixing device of the first embodiment except that the fixing roller is configured as described below. In the second embodiment, the same members and portions as those of the fixing device of the first embodiment are denoted by the same reference numerals and the description thereof is omitted. In the fixing device 100 according to the second exemplary embodiment, a fixing roller having a plurality of rubber layers made of different materials in the radial direction of the fixing roller is used as the fixing roller 130. The feature is that the surface of the heating film 120 is reduced by reducing the micro hardness of the surface of the fixing roller 130.

定着ローラの構成：前述したように、回転接触式の定着装置は、定着ローラ表面を加熱し、加熱された定着ローラ表面の熱を利用して記録材上のトナー像の定着を行うように構成されている。定着ローラは、弾性ゴム層の熱容量が大きく、且つ、熱伝導率が高いと、加熱ニップ部Ｎ２でヒータ１１５から加熱フィルム１２０を介して定着ローラ表面から受ける熱が定着ローラ内部へ吸収され易く、定着ローラの表面温度が上昇しにくくなる。しかし、弾性ゴム層の熱容量が小さく、且つ、熱伝導率が低いだけであると、定着ローラの表面温度は上昇しやすいが、最表層（離型層）しか暖まらないため記録材上のトナー像の定着を行うには熱量が足りない場合がある。そこで、本実施例２の定着ローラ１３０は、定着ローラ半径方向の最外ゴム層としての蓄熱ゴム層１３３と、断熱ゴム層１３２と、の２層のゴム層で弾性ゴム層を構成した。蓄熱ゴム層１３３で定着ローラ１３０表面に熱を溜めることができ、断熱ゴム層１３２で定着ローラ１３０内部への熱の逃げを防止することができる。この定着ローラ１３０を用いた定着装置１００は、定着ローラ１３０の蓄熱効果と断熱効果の相乗効果によって立ち上げ時間を大幅に短縮できるというメリットがある。図４の（ａ）は本実施例２に係る定着装置における定着ローラの層構成を表わす横断面模式図である。定着ローラ１３０は、芯金１３１の外周面上に断熱ゴム層１３２を設け、断熱ゴム層１３２の外周面上に蓄熱ゴム層１３３を設け、蓄熱ゴム層１３３の外周面上に離型層１１８を設けた構成となっている。断熱ゴム層１３２は、定着ローラ１３０内部へ熱を逃さないようにできるだけ低熱容量で、且つ、熱伝導率が低く、断熱効果の高い材料が良い。断熱ゴム層１３２の材料としては、例えば、０．２〜０．３Ｗ／ｍ・Ｋ程度の低熱伝導率ソリッドゴムを発泡させたり、中空のガラスビーズを入れたりし、熱伝導率を０．２Ｗ／ｍ・Ｋ以下にした低熱伝導率ゴムを用いると良い。また断熱ゴム層１３２の厚さは、芯金１３１へ熱を逃さないように厚い方が良いが、厚すぎると定着装置が大きくなってしまうため１〜５ｍｍ程度の厚さが好ましい。本実施例２では、断熱ゴム層１３２の材料として、ソリッドゴムを発泡させ熱伝導率を０．１１〜０．１６Ｗ／ｍ・Ｋ程度にした発泡ゴムを用いた。断熱ゴム層１３２の厚さは４ｍｍとした。一方、蓄熱ゴム層１３３は、加熱フィルム１２０表面からの熱を素早く蓄熱するために熱伝導率が高い方が良い。蓄熱ゴム層１３３の材料としては、ソリッドゴムに熱伝導フィラーを添加するなどし、熱伝導率を０．５Ｗ／ｍ・Ｋ以上にしたものを用いるのが好ましい。蓄熱ゴム層１３３の熱容量は、ゴムの熱伝導率（比重）とその厚さにより調整し、画像形成装置の印字速度に合せて、３０μｍ〜１ｍｍ程度にして用いると良い。本実施例２では、加熱フィルム１２０表面の汚れを低減するために、定着ローラ１３０表面のマイクロ硬度を低くしている。定着ローラ１３０表面のマイクロ硬度を低くするために、蓄熱ゴム層１３３のゴム材料と厚さを調整している。   Fixing roller configuration: As described above, the rotary contact type fixing device is configured to heat the surface of the fixing roller and fix the toner image on the recording material using the heat of the heated fixing roller surface. Has been. When the heat capacity of the elastic rubber layer is large and the heat conductivity is high, the fixing roller easily absorbs heat received from the surface of the fixing roller from the heater 115 via the heating film 120 in the heating nip portion N2, into the fixing roller. The surface temperature of the fixing roller is unlikely to rise. However, if the elastic rubber layer has a small heat capacity and only a low thermal conductivity, the surface temperature of the fixing roller tends to rise, but only the outermost layer (release layer) is warmed, so the toner image on the recording material. The amount of heat may not be sufficient for fixing. Therefore, in the fixing roller 130 of the second embodiment, an elastic rubber layer is configured by two rubber layers of the heat storage rubber layer 133 as the outermost rubber layer in the fixing roller radial direction and the heat insulating rubber layer 132. The heat storage rubber layer 133 can accumulate heat on the surface of the fixing roller 130, and the heat insulating rubber layer 132 can prevent heat from escaping into the fixing roller 130. The fixing device 100 using the fixing roller 130 has an advantage that the start-up time can be greatly shortened by a synergistic effect of the heat storage effect and the heat insulating effect of the fixing roller 130. FIG. 4A is a schematic cross-sectional view showing the layer structure of the fixing roller in the fixing device according to the second embodiment. In the fixing roller 130, a heat insulating rubber layer 132 is provided on the outer peripheral surface of the core metal 131, a heat storage rubber layer 133 is provided on the outer peripheral surface of the heat insulating rubber layer 132, and a release layer 118 is provided on the outer peripheral surface of the heat storage rubber layer 133. It has a configuration provided. The heat insulating rubber layer 132 is preferably made of a material having a heat capacity as low as possible, a low heat conductivity, and a high heat insulating effect so that heat does not escape into the fixing roller 130. As a material of the heat insulating rubber layer 132, for example, low thermal conductivity solid rubber of about 0.2 to 0.3 W / m · K is foamed or hollow glass beads are inserted, and the thermal conductivity is 0.2 W. It is preferable to use a rubber having a low thermal conductivity of not more than / m · K. The heat insulating rubber layer 132 is preferably thick so as not to allow heat to escape to the cored bar 131. However, if the thickness is too large, the fixing device becomes large, and a thickness of about 1 to 5 mm is preferable. In the second embodiment, as the material for the heat insulating rubber layer 132, foamed rubber in which solid rubber is foamed to have a thermal conductivity of about 0.11 to 0.16 W / m · K is used. The thickness of the heat insulating rubber layer 132 was 4 mm. On the other hand, the heat storage rubber layer 133 preferably has a high thermal conductivity in order to quickly store heat from the surface of the heating film 120. As a material for the heat storage rubber layer 133, it is preferable to use a material having a heat conductivity of 0.5 W / m · K or more by adding a heat conductive filler to solid rubber. The heat capacity of the heat storage rubber layer 133 is adjusted by the thermal conductivity (specific gravity) of the rubber and its thickness, and is preferably set to about 30 μm to 1 mm in accordance with the printing speed of the image forming apparatus. In the second embodiment, the micro hardness of the surface of the fixing roller 130 is lowered in order to reduce the contamination on the surface of the heating film 120. In order to reduce the micro hardness of the surface of the fixing roller 130, the rubber material and the thickness of the heat storage rubber layer 133 are adjusted.

蓄熱ゴム層とマイクロ硬度との関係：蓄熱ゴム層は、ゴム材料の硬度（ＪＩＳ−Ａ硬度）が低く、厚さが薄いほど定着ローラ表面のマイクロ硬度が低くなることが以下の実験でわかった。蓄熱ゴム層の材料ゴム硬度（ＪＩＳ−Ａ硬度）と、蓄熱ゴム層の厚みと、をそれぞれ変えて、８種類の実験用定着ローラ（表３参照)を作製した。そしてこの８種類の定着ローラについて、実施例１の実験と同様に、各定着ローラのマイクロ硬度の測定と、通紙耐久により加熱フィルムの汚れの比較を行った。表３において、（ｉ）蓄熱ゴム層の材料ゴム硬度違いは、蓄熱ゴム層の厚みを１００μｍ、熱伝導率を１．５Ｗ／ｍ・Ｋで統一して比較した。（ｉｉ）蓄熱ゴム層の厚み違いは、蓄熱ゴム層のＪＩＳ−Ａ硬度を６０度、熱伝導率を１．５Ｗ／ｍ・Ｋで統一して比較した。また（ｉ）、（ｉｉ）の比較も、離型層は、厚さ１５μｍのＰＦＡチューブを用いた。加熱フィルム表面の汚れの比較は、実施例１と同様、１０００枚の通紙耐久後（定着装置の耐久寿命の１／５０）に行った。すなわち、透明な粘着テープで加熱フィルム表面から汚れを剥がし、粘着テープで剥がした汚れを光学式濃度計により濃度測定を行なうことで各定着ローラ表面における加熱フィルム表面の汚れ量を定量化し比較した。結果を表３に示す。   The relationship between the heat storage rubber layer and the micro hardness: The heat storage rubber layer has a lower hardness (JIS-A hardness) of the rubber material. . Eight types of experimental fixing rollers (see Table 3) were prepared by changing the material rubber hardness (JIS-A hardness) of the heat storage rubber layer and the thickness of the heat storage rubber layer. Then, for the eight types of fixing rollers, as in the experiment of Example 1, the micro hardness of each fixing roller was measured, and the contamination of the heating film was compared based on the paper passing durability. In Table 3, (i) The difference in material rubber hardness of the heat storage rubber layer was compared by unifying the thickness of the heat storage rubber layer at 100 μm and the thermal conductivity of 1.5 W / m · K. (Ii) The difference in thickness of the heat storage rubber layer was compared by unifying the heat storage rubber layer with a JIS-A hardness of 60 degrees and a thermal conductivity of 1.5 W / m · K. For comparison between (i) and (ii), a PFA tube having a thickness of 15 μm was used as the release layer. The comparison of the stain on the surface of the heating film was performed after the endurance of passing 1000 sheets (1/50 of the endurance life of the fixing device) as in Example 1. That is, the dirt was removed from the surface of the heating film with a transparent adhesive tape, and the amount of dirt on the surface of the heating film on each fixing roller surface was quantified and compared by measuring the density of the dirt removed with the adhesive tape using an optical densitometer. The results are shown in Table 3.

表３に示すように、（ｉ）蓄熱ゴム層の材料ゴム硬度違いの結果は、ゴム材料硬度が高くなるほど、マイクロ硬度が高くなり、加熱フィルム表面の汚れ濃度が濃くなる結果だった。また（ｉｉ）蓄熱ゴム層の厚み違いの結果は、蓄熱ゴム層の厚みが厚くなるほど、マイクロ硬度が高くなり、加熱フィルム表面の汚れ濃度が濃くなる結果だった。（ｉ）と（ｉｉ）の結果より、定着ローラ表面の蓄熱ゴム層のゴム材料の硬度が低く、厚さが薄いほど、定着ローラ表面のマイクロ硬度が低くなり、加熱フィルム表面が汚れにくいことが分かった。 As shown in Table 3, (i) the result of the difference in material rubber hardness of the heat storage rubber layer was that the higher the rubber material hardness, the higher the micro hardness and the higher the dirt concentration on the surface of the heating film. Moreover, (ii) The result of the difference in thickness of the heat storage rubber layer was that the greater the thickness of the heat storage rubber layer, the higher the micro hardness and the higher the dirt concentration on the surface of the heating film. From the results of (i) and (ii), the hardness of the rubber material of the heat storage rubber layer on the surface of the fixing roller is lower, and the thinner the thickness is, the lower the micro hardness of the surface of the fixing roller is. I understood.

マイクロ硬度と画像不良との関係：（ｉｉ）蓄熱ゴム層の厚み違いで加熱フィルム表面の汚れの比較を行なった４本の定着ローラについて、実施例１と同様に、定着装置の寿命の２倍である１０万枚まで印字耐久を行った。そして加熱フィルム表面の汚れによる定着不良及び汚れの吐き出しによる画像不良の発生有無を調査した。結果を表４に示す。   Relationship between micro hardness and image defect: (ii) For the four fixing rollers for which the comparison of the dirt on the surface of the heating film due to the difference in the thickness of the heat storage rubber layer, as in Example 1, twice the life of the fixing device Printing durability was performed up to 100,000 sheets. Then, the occurrence of fixing failure due to contamination on the surface of the heating film and the occurrence of image failure due to discharge of the contamination was investigated. The results are shown in Table 4.

表４に示すように、蓄熱ゴム層の厚みが５０μｍ、マイクロ硬度３３度の定着ローラは、定着装置の耐久寿命の２倍である１０万枚まで定着不良及び汚れの吐き出しによる画像不良の発生は無かった。蓄熱ゴム層の厚みが１００μｍ、マイクロ硬度４２度の定着ローラと、蓄熱ゴム層の厚みが２００μｍ、マイクロ硬度５０度の定着ローラは、それぞれ、１０万枚時点で定着性の低下は見られたものの、画像不良の発生は無かった。蓄熱ゴム層の厚みが３００μｍ、マイクロ硬度５８度の定着ローラは、定着装置の耐久寿命である５万枚から定着性の低下が見られ、７．５万枚以上で定着不良が発生し、１０万枚時点で画像不良も発生してしまった。断熱ゴム層と蓄熱ゴム層を有する定着ローラにおいても、定着ローラ表面のマイクロ硬度は低いほど定着不良や汚れの吐き出しによる画像不良が発生しにくい。少なくともマイクロ硬度が５０未満（Ｈμ＜５０）であり、蓄熱ゴム層の厚みが２００μｍ以下であれば、定着不良及び画像不良の発生は無く、十分な加熱フィルム表面の汚れ低減効果が得られることがわかった。 As shown in Table 4, with a fixing roller having a heat storage rubber layer thickness of 50 μm and a micro hardness of 33 degrees, up to 100,000 sheets, which is twice the endurance life of the fixing device, causes poor fixing and image defects due to smudge discharge. There was no. A fixing roller with a heat storage rubber layer thickness of 100 μm and a micro hardness of 42 degrees, and a fixing roller with a heat storage rubber layer thickness of 200 μm and a micro hardness of 50 degrees, although a decrease in fixability was observed at the time of 100,000 sheets, respectively. No image defect occurred. A fixing roller having a heat storage rubber layer thickness of 300 μm and a micro hardness of 58 degrees shows a decrease in fixing property from 50,000 sheets, which is the durable life of the fixing device, and a fixing defect occurs when the number of sheets exceeds 75,000. Image defects occurred at the time of 10,000 sheets. Even in a fixing roller having a heat insulating rubber layer and a heat storage rubber layer, the lower the micro hardness of the surface of the fixing roller, the less likely to cause image defects due to poor fixing or smudge discharge. If at least the micro hardness is less than 50 (Hμ <50) and the thickness of the heat storage rubber layer is 200 μm or less, there is no occurrence of fixing failure and image failure, and a sufficient effect of reducing stains on the heated film surface can be obtained. all right.

蓄熱ゴム層の硬度とマイクロ硬度の説明：本実施例２では、定着ローラ１３０表面のマイクロ硬度Ｈμを低くする（Ｈμ＜５０）ために、蓄熱ゴム層１３３の材料として低硬度ゴムを使用した。また蓄熱ゴム層１３３の厚さは断熱ゴム層１３２よりも薄くした。表３（ｉ）に示すように、蓄熱ゴム層１３３の厚さが１００μｍの場合、蓄熱ゴム層１３３のＪＩＳ−Ａ硬度は７０度未満であれば、定着ローラ１３０表面のマイクロ硬度Ｈμが５０度未満となるため、十分な加熱フィルム表面の汚れ低減効果が得られる。本実施例２では、より加熱フィルム表面の汚れ低減効果を高めるために、蓄熱ゴム層１３３のゴム材料として、ＪＩＳ−Ａ硬度が５１度の低硬度ゴムを用い、厚さを５０μｍに薄肉化することで、定着ローラ表面のマイクロ硬度を２７度と低硬度化したものを用いた。蓄熱ゴム層１３３の熱伝導率は１．５Ｗ／ｍ・Ｋである。離型層１１８は、実施例１の定着ローラ１１０と同様、１５μｍのＰＦＡチューブを用いた。本実施例２の定着ローラ１３０においても、表４と同様の通紙耐久試験を行った。定着ローラ１３０は、定着ローラ表面のマイクロ硬度が低い（５０度未満）ため、加熱フィルム表面の汚れを抑えることができ、定着装置の耐久寿命の２倍である１０万枚まで定着不良、及び加熱フィルム表面の汚れの吐き出しによる画像不良の発生は無かった。断熱ゴム層１３２と蓄熱ゴム層１３３のゴム材料及び厚さと、離型層１８８の材料及び厚さは上述のものに限られない。定着ローラ１３０表面のマイクロ硬度を少なくとも５０度未満に抑えるように断熱ゴム層１３２と蓄熱ゴム層１３３のゴム材料及び厚さと、離型層１８８の材料及び厚さを調整することにより、上記と同様の作用効果が得られる。   Explanation of Hardness and Micro Hardness of Thermal Storage Rubber Layer: In the second embodiment, low hardness rubber was used as a material for the thermal storage rubber layer 133 in order to reduce the micro hardness Hμ on the surface of the fixing roller 130 (Hμ <50). The thickness of the heat storage rubber layer 133 was made thinner than that of the heat insulating rubber layer 132. As shown in Table 3 (i), when the heat storage rubber layer 133 has a thickness of 100 μm, if the JIS-A hardness of the heat storage rubber layer 133 is less than 70 degrees, the micro hardness Hμ of the surface of the fixing roller 130 is 50 degrees. Therefore, a sufficient effect of reducing dirt on the heated film surface can be obtained. In Example 2, in order to further enhance the effect of reducing the dirt on the surface of the heating film, a low hardness rubber having a JIS-A hardness of 51 degrees is used as the rubber material of the heat storage rubber layer 133, and the thickness is reduced to 50 μm. As a result, the microhardness of the fixing roller surface reduced to 27 degrees was used. The thermal conductivity of the heat storage rubber layer 133 is 1.5 W / m · K. As the release layer 118, a 15 μm PFA tube was used as in the fixing roller 110 of Example 1. Also for the fixing roller 130 of the second embodiment, the same paper passing durability test as in Table 4 was performed. Since the fixing roller 130 has a low micro hardness (less than 50 degrees) on the surface of the fixing roller, it is possible to suppress contamination on the surface of the heating film, defective fixing, and heating up to 100,000 sheets, which is twice the durable life of the fixing device. There was no occurrence of image defects due to discharge of dirt on the film surface. The rubber material and thickness of the heat insulating rubber layer 132 and the heat storage rubber layer 133 and the material and thickness of the release layer 188 are not limited to those described above. By adjusting the rubber material and thickness of the heat insulating rubber layer 132 and the heat storage rubber layer 133 and the material and thickness of the release layer 188 so as to suppress the micro hardness of the surface of the fixing roller 130 to at least less than 50 degrees, the same as described above. The following effects can be obtained.

［実施例３］定着装置の他の例を説明する。本実施例３に示す定着装置は、定着ローラを後述のように構成した点を除いて、実施例１の定着装置と同じ構成としてある。本実施例３においても、実施例１の定着装置と同じ部材・部分については、同一の符号を付し再度の説明を省略する。本実施例３の定着装置１００は、定着ローラの最表層の離型層をスプレーコートにより形成することで定着ローラ表面のマイクロ硬度を低くし、加熱フィルム１２０表面の汚れを低減することを特徴としている。   [Embodiment 3] Another example of the fixing device will be described. The fixing device shown in the third embodiment has the same configuration as the fixing device of the first embodiment except that the fixing roller is configured as described below. Also in the third embodiment, the same members and portions as those of the fixing device of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The fixing device 100 according to the third exemplary embodiment is characterized in that the outermost surface release layer of the fixing roller is formed by spray coating, thereby reducing the micro hardness of the surface of the fixing roller and reducing the contamination on the surface of the heating film 120. Yes.

スプレーコートの離型層の説明：定着ローラの最表層の離型層は、実施例１及び実施例２のようにフッ素樹脂のチューブを被覆しても良いが、スプレーコートによってフッ素離型層を形成すると定着ローラ表面のマイクロ硬度が低くなることが分かった。離型層をチューブで成型する場合、一般的には押出し成型により成型する。押出し成型は、ペレット上のフッ素樹脂を熱で溶融させ、スクリューで混ぜながら圧をかけて押出す。このときＰＦＡの分子鎖が混練りと加圧により絡み合い、分子鎖が絡み合ったフッ素チューブとなる。一方、スプレーコートによるフッ素膜の形成は、フッ素の微粒子を水に分散させた液（ディスパージョン）を定着ローラ表面にスプレーにより吹き付け焼成を行い形成する方法である。スプレーによりフッ素樹脂を形成する場合は、フッ素粒子が定着ローラ表面に付着した後、そのまま焼成されるため、チューブの押し出し成型とは異なり、混練りと加圧工程が無い。そのためスプレーコートによるフッ素膜は、フッ素の分子鎖が絡み合わないフッ素膜となり、チューブの押し出し成型よりも柔らかくなる。定着ローラの離型層をスプレーコートで形成すると、同じ膜厚でチューブにより離型層を被覆した場合より、定着ローラ表面のマイクロ硬度を１〜１０度程度低くすることができる。そのため、離型層をスプレーコートで形成した定着ローラは、チューブで形成した場合よりも加熱ニップ部Ｎ２での汚れの包み込み性が向上し、加熱フィルム１２０表面への汚れの付着を低減することができる。また押出し成型のチューブの場合、１０μｍ以下の薄肉成型が困難であり、また１０μｍ以下で成型した場合でも、定着ローラの弾性ゴム層への被覆などの取り扱いが困難となる。一方、スプレーコートは、直接定着ローラの弾性ゴム層へ塗工するため１０μｍ以下の薄肉化が可能であり、上述のように、離型層を薄肉化することで、更に定着ローラ表面のマイクロ硬度を低くすることができる。また離型層の薄肉化により加熱フィルム１２０の熱が定着ローラ表面に伝わりやすくなるため、定着ローラの表面温度の立ち上がりを短縮化できる。   Explanation of the release layer of the spray coating: The outermost release layer of the fixing roller may be covered with a fluororesin tube as in Example 1 and Example 2, but the fluorine release layer is formed by spray coating. It has been found that the micro hardness of the surface of the fixing roller is lowered when formed. When the release layer is molded with a tube, it is generally molded by extrusion molding. In the extrusion molding, the fluororesin on the pellet is melted by heat and extruded while being mixed with a screw. At this time, the molecular chain of PFA is entangled by kneading and pressurization, resulting in a fluorine tube in which the molecular chain is entangled. On the other hand, the formation of a fluorine film by spray coating is a method in which a liquid (dispersion) in which fluorine fine particles are dispersed in water is sprayed onto the surface of the fixing roller by spraying and is formed. When the fluororesin is formed by spraying, since the fluorine particles adhere to the surface of the fixing roller and are baked as they are, there are no kneading and pressurizing steps unlike tube extrusion molding. Therefore, the fluorine film by spray coating becomes a fluorine film in which the molecular chains of fluorine are not entangled, and becomes softer than the extrusion molding of the tube. When the release layer of the fixing roller is formed by spray coating, the micro hardness of the surface of the fixing roller can be lowered by about 1 to 10 degrees as compared with the case where the release layer is covered with a tube with the same film thickness. Therefore, the fixing roller in which the release layer is formed by spray coating has improved dirt wrapping property at the heating nip portion N2 compared to the case where the release layer is formed by a tube, and the adhesion of dirt to the surface of the heating film 120 can be reduced. it can. Further, in the case of an extruded tube, it is difficult to form a thin wall having a thickness of 10 μm or less, and even when the tube is molded at a thickness of 10 μm or less, it is difficult to handle the fixing roller on the elastic rubber layer. On the other hand, since spray coating is applied directly to the elastic rubber layer of the fixing roller, it is possible to reduce the thickness to 10 μm or less. As described above, the microhardness of the surface of the fixing roller can be further reduced by reducing the thickness of the release layer. Can be lowered. Further, since the heat of the heating film 120 is easily transmitted to the surface of the fixing roller by thinning the release layer, the rise of the surface temperature of the fixing roller can be shortened.

定着ローラの構成：本実施例３の定着ローラは、実施例２の定着ローラと同様に、芯金と、断熱ゴム層と、蓄熱ゴム層と、離型層と、を有している。芯金と、断熱ゴム層と、蓄熱ゴム層は、それぞれ、実施例２と同じであり、離型層のみが異なる。本実施例３の定着ローラの離型層は、ＰＦＡをスプレーコートにより厚さ１０μｍで形成した。本実施例３の定着ローラ表面のマイクロ硬度は、実施例２の定着ローラ１３０表面のマイクロ硬度に比べて４度低い２３度であった。本実施例３の定着ローラにおいても、実施例２と同様の通紙耐久試験を行った。この定着ローラは、定着ローラ表面のマイクロ硬度が低い（５０度未満）ため、加熱フィルム表面の汚れを低減することができ、定着装置の寿命の２倍である１０万枚まで定着不良及び加熱フィルム表面の汚れの吐き出しによる画像不良の発生は無かった。   Configuration of Fixing Roller: The fixing roller of the third embodiment has a cored bar, a heat insulating rubber layer, a heat storage rubber layer, and a release layer, like the fixing roller of the second embodiment. The core metal, the heat insulating rubber layer, and the heat storage rubber layer are the same as those in the second embodiment, and only the release layer is different. The release layer of the fixing roller of Example 3 was formed by spray coating PFA with a thickness of 10 μm. The micro hardness of the surface of the fixing roller of Example 3 was 23 degrees, which is 4 degrees lower than the micro hardness of the surface of the fixing roller 130 of Example 2. The fixing roller of Example 3 was also subjected to a paper passing durability test similar to that of Example 2. Since this fixing roller has a low micro hardness (less than 50 degrees) on the surface of the fixing roller, it is possible to reduce contamination on the surface of the heating film, and fixing defects up to 100,000 sheets, which is twice the life of the fixing device, and the heating film There was no occurrence of image defects due to discharge of dirt on the surface.

［実施例４］実施例１乃至実施例３に示す定着装置では離型層を有する定着ローラについて説明したが、定着ローラはこれに限られず離型層を有していない定着ローラであってもよい。この場合、定着ローラの弾性ゴム層又は蓄熱ゴム層の材料として離型性の良いシリコーンゴムやフッ素ゴムなどの低硬度材料のゴム材料を用い、このゴム材料表面のマイクロ硬度を５０度未満に設定すれば、加熱フィルム１２０表面の汚れを低減することができる。   [Embodiment 4] In the fixing devices shown in Embodiments 1 to 3, the fixing roller having the release layer has been described. However, the fixing roller is not limited to this and may be a fixing roller having no release layer. Good. In this case, a rubber material of a low hardness material such as silicone rubber or fluorine rubber having good releasability is used as a material of the elastic rubber layer or the heat storage rubber layer of the fixing roller, and the micro hardness of the rubber material surface is set to less than 50 degrees. If it does so, the stain | pollution | contamination on the surface of the heating film 120 can be reduced.

[実施例５]実施例１乃至実施例３に示す定着装置では加熱回転部材として加熱フィルム１２０を用いた例を説明したが、加熱回転部材はこれに限られず筒状の回転可能な加熱ローラであってもよい。図４の（ｂ）は本実施例５に係る定着装置の構成を表わす横断面模式図である。加熱ローラ１４０は、剛性を有するローラ本体１４１と、離型層１４２と、を有している。ローラ本体１４１は、耐熱性及び熱伝導性を有する所定の金属材料又は樹脂材料によって筒状に形成されている。そしてこのローラ本体１４１の長手方向両端部の支持軸部を除く外周面上には、ローラ本体１４１の外周面の汚れを低減するためＰＦＡの離型層１４２が設けられている。この加熱ローラ１４０はローラ本体１４１の長手方向両端部の支持軸部が軸受（不図示）を介して装置フレーム（不図示）に回転自在に支持され、この軸受を加圧バネ１１４で下方向Ａ１へ加圧している。これにより加熱ローラ１４０の外周面（表面）を定着ローラ１１０表面に加圧状態に接触させ定着ローラ１１０の弾性ゴム層１１６を弾性変形させることによって、加熱ローラ１４０表面と定着ローラ１１０表面との間に所定幅の加熱ニップ部Ｎ２を形成している。この加熱ローラ１４０は定着ローラ１１０の回転に追従して矢印方向に回転し、ローラ本体１４１内に設けられた加熱体としてのハロゲンランプ１４３によって加熱される。本実施例５の定着装置１００においても、定着ローラ１１０表面のマイクロ硬度を５０度未満に設定すれば、加熱ローラ１４０表面の汚れを低減することができる。   [Embodiment 5] In the fixing devices shown in Embodiments 1 to 3, the example in which the heating film 120 is used as the heating rotating member has been described. However, the heating rotating member is not limited to this and is a cylindrical rotatable heating roller. There may be. FIG. 4B is a schematic cross-sectional view illustrating the configuration of the fixing device according to the fifth embodiment. The heating roller 140 has a rigid roller body 141 and a release layer 142. The roller body 141 is formed in a cylindrical shape from a predetermined metal material or resin material having heat resistance and thermal conductivity. A PFA release layer 142 is provided on the outer peripheral surface excluding the support shafts at both ends in the longitudinal direction of the roller main body 141 in order to reduce contamination on the outer peripheral surface of the roller main body 141. The heating roller 140 has support shafts at both ends in the longitudinal direction of the roller body 141 rotatably supported by an apparatus frame (not shown) via a bearing (not shown), and the bearing is supported by a pressure spring 114 in the downward direction A1. Is being pressurized. As a result, the outer peripheral surface (surface) of the heating roller 140 is brought into contact with the surface of the fixing roller 110 in a pressurized state, and the elastic rubber layer 116 of the fixing roller 110 is elastically deformed. A heating nip portion N2 having a predetermined width is formed on the surface. The heating roller 140 rotates in the direction of the arrow following the rotation of the fixing roller 110 and is heated by a halogen lamp 143 serving as a heating body provided in the roller body 141. Also in the fixing device 100 according to the fifth exemplary embodiment, if the micro hardness of the surface of the fixing roller 110 is set to less than 50 degrees, the contamination on the surface of the heating roller 140 can be reduced.

[実施例６]実施例１乃至実施例３に示す定着装置ではバックアップ部材として加圧ローラ１１１を用いた例を説明したが、バックアップ部材はこれに限られず回転しないパッド部材であってもよい。図４の（ｃ）は本実施例６に係る定着装置の構成を表わす横断面模式図である。パッド部材１５０は、所定の材料によって細長い板状に形成されている。このパッド部材１５０は、装置フレーム（不図示）に支持させた長手方向両端部の支持部を加圧バネ１２４で上方向Ａ２へ加圧しパッド部材１５０の上面（表面）を定着ローラ１１０表面に加圧状態に接触させている。これにより定着ローラ１１０の弾性ゴム層１１６を弾性変形させ、パッド部材１５０表面と定着ローラ１１０表面との間に所定幅の定着ニップ部Ｎ１を形成している。本実施例６の定着装置１００においても、定着ローラ１１０表面のマイクロ硬度を５０度未満に設定すれば、加熱フィルム１２０表面の汚れを低減することができる。   [Embodiment 6] In the fixing devices shown in Embodiments 1 to 3, the example in which the pressure roller 111 is used as the backup member has been described. However, the backup member is not limited to this and may be a pad member that does not rotate. FIG. 4C is a schematic cross-sectional view illustrating the configuration of the fixing device according to the sixth embodiment. The pad member 150 is formed in an elongated plate shape with a predetermined material. The pad member 150 presses the support portions at both ends in the longitudinal direction supported by an apparatus frame (not shown) in the upward direction A2 by the pressure spring 124, and applies the upper surface (surface) of the pad member 150 to the surface of the fixing roller 110. In contact with pressure. As a result, the elastic rubber layer 116 of the fixing roller 110 is elastically deformed, and a fixing nip portion N1 having a predetermined width is formed between the surface of the pad member 150 and the surface of the fixing roller 110. Also in the fixing device 100 according to the sixth embodiment, if the micro hardness of the surface of the fixing roller 110 is set to less than 50 degrees, the contamination on the surface of the heating film 120 can be reduced.

１１０：定着ローラ、１１１：加圧ローラ、１１６：弾性ゴム層、１１８：離型層、１２０：加熱フィルム、１３３：蓄熱ゴム層、１４０：加熱ローラ、１５０：パッド部材、Ｎ１：定着ニップ部、Ｎ２：加熱ニップ部、Ｐ：記録材、ｔ：トナー像 110: fixing roller, 111: pressure roller, 116: elastic rubber layer, 118: release layer, 120: heated film, 133: heat storage rubber layer, 140: heating roller, 150: pad member, N1: fixing nip, N2: heating nip, P: recording material, t: toner image

Claims (12)

加熱回転部材と、弾性ゴム層を有する定着ローラであり前記加熱回転部材と接触して加熱ニップ部を形成する定着ローラと、前記定着ローラと接触して定着ニップ部を形成するバックアップ部材と、を有し、前記加熱回転部材は前記加熱ニップ部で前記定着ローラの表面を加熱し、前記定着ニップ部でトナー像を担持する記録材を挟持搬送しつつ前記定着ローラ表面でトナー像を記録材上に加熱定着する定着装置において、前記定着ローラ表面のマイクロ硬度をＨμとすると、Ｈμ＜５０を満たすことを特徴とする定着装置。   A heating roller, a fixing roller having an elastic rubber layer, which contacts the heating roller and forms a heating nip, and a backup member that contacts the fixing roller and forms a fixing nip. The heating rotating member heats the surface of the fixing roller at the heating nip portion, and holds the toner image on the recording material while holding and conveying the recording material carrying the toner image at the fixing nip portion. In the fixing device for heat fixing, a fixing device satisfying Hμ <50, where Hμ is the micro hardness of the surface of the fixing roller. 前記定着ローラの弾性ゴム層は、単層であ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 elastic rubber layer of the fixing roller is a single layer. 前記定着ローラの弾性ゴム層は、前記定着ローラの半径方向に異なる複数のゴム層からな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 elastic rubber layer of the fixing roller includes a plurality of rubber layers different in a radial direction of the fixing roller. 前記定着ローラの弾性ゴム層において、前記定着ローラ半径方向の最外ゴム層の厚さは、２００μｍ以下であることを特徴とする請求項３に記載の定着装置。   The fixing device according to claim 3, wherein in the elastic rubber layer of the fixing roller, the outermost rubber layer in the radial direction of the fixing roller has a thickness of 200 μm or less. 前記定着ローラの弾性ゴム層において、前記定着ローラ半径方向の最外ゴム層に用いるゴムのＪＩＳ−Ａ硬度は、７０度未満であることを特徴とする請求項３に記載の定着装置。   The fixing device according to claim 3, wherein the elastic rubber layer of the fixing roller has a JIS-A hardness of rubber used for the outermost rubber layer in the radial direction of the fixing roller of less than 70 degrees. 前記定着ローラの弾性ゴム層の外側にフッ素系材料からなる離型層を有することを特徴とする請求項１乃至請求項５の何れか１項に記載の定着装置。   The fixing device according to claim 1, further comprising a release layer made of a fluorine-based material outside the elastic rubber layer of the fixing roller. 前記定着ローラの前記離型層の厚みは、３０μｍ以下であることを特徴とする請求項６に記載の定着装置。   The fixing device according to claim 6, wherein a thickness of the release layer of the fixing roller is 30 μm or less. 前記定着ローラの前記離型層は、スプレーコートにより形成されたことを特徴とする請求項６に記載の定着装置。   The fixing device according to claim 6, wherein the release layer of the fixing roller is formed by spray coating. 前記加熱回転部材は、可撓性を有する無端状の加熱フィルムであ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 heating rotating member is an endless heating film having flexibility. 前記加熱回転部材は、筒状の加熱ローラであ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 heating rotation member is a cylindrical heating roller. 前記バックアップ部材は、回転可能な加圧ローラであ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 backup member is a rotatable pressure roller. 前記バックアップ部材は、回転しないパッド部材であ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 backup member is a pad member that does not rotate.
JP2009246337A 2009-10-27 2009-10-27 Fixing device Pending JP2011095306A (en)

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