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JP6638530B2 - Fixing device, image forming device - Google Patents

Fixing device, image forming device Download PDF

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Publication number
JP6638530B2
JP6638530B2 JP2016075820A JP2016075820A JP6638530B2 JP 6638530 B2 JP6638530 B2 JP 6638530B2 JP 2016075820 A JP2016075820 A JP 2016075820A JP 2016075820 A JP2016075820 A JP 2016075820A JP 6638530 B2 JP6638530 B2 JP 6638530B2
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fixing
heat
fixing device
contact
posture
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JP2017187599A (en
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荒井 裕司
裕司 荒井
皓一 宇都宮
皓一 宇都宮
後藤 創
創 後藤
高広 今田
高広 今田
卓弥 瀬下
卓弥 瀬下
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Ricoh Co Ltd
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Ricoh Co Ltd
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Description

本発明は、定着装置および定着装置を備えた複写機、プリンタ、ファクシミリ、またはそれらの複合機における画像形成装置に関する。   The present invention relates to a fixing device and an image forming apparatus in a copier, a printer, a facsimile, or a multifunction peripheral including the fixing device.

画像形成装置では、電子写真記録・静電記録・磁気記録等の画像形成プロセスにより、画像転写方式又は直接方式によって未定着トナー画像が記録媒体シート・印刷紙・感光紙・静電記録紙等の記録媒体に形成される。未定着トナー画像を定着させるための定着装置としては、熱ローラ方式、フィルム加熱方式、電磁誘導加熱方式等の接触加熱方式の定着装置が広く採用されている。   In an image forming apparatus, an unfixed toner image is transferred to a recording medium sheet, printing paper, photosensitive paper, electrostatic recording paper, or the like by an image transfer method or a direct method by an image forming process such as electrophotographic recording, electrostatic recording, or magnetic recording. It is formed on a recording medium. As a fixing device for fixing an unfixed toner image, a contact heating type fixing device such as a heat roller system, a film heating system, and an electromagnetic induction heating system is widely used.

また、定着時間の短縮化および装置の省エネルギー化等を目的として、低熱容量の無端ベルトを、金属熱伝導体を介さずに加熱する構成の定着装置が採用されている。   Further, for the purpose of shortening the fixing time and saving the energy of the apparatus, a fixing apparatus having a configuration in which an endless belt having a low heat capacity is heated without a metal heat conductor is used.

しかし、上記の様な低熱容量の定着部材を用いた定着装置の場合、定着部材の幅方向端部の非通紙領域における過剰な温度上昇が問題となる場合がある。つまり、定着装置に通紙される用紙のサイズは様々であるため、用紙サイズと定着部材の加熱範囲が必ずしも一致するわけではない。そして、定着装置に通紙される用紙サイズが加熱源による加熱範囲よりも小さい場合、通紙領域では用紙や用紙上のトナーを定着させるために熱が消費されるが、非通紙領域では、定着部材から熱が奪われないため、主に定着部材の幅方向端部における非通紙領域で定着部材が過剰に温度上昇してしまう。   However, in the case of a fixing device using a fixing member having a low heat capacity as described above, an excessive rise in temperature in the non-sheet passing area at the widthwise end of the fixing member may be a problem. That is, since the size of the sheet passed through the fixing device is various, the sheet size and the heating range of the fixing member do not always match. When the size of the sheet passed through the fixing device is smaller than the heating range of the heating source, heat is consumed to fix the sheet or the toner on the sheet in the sheet passing area, but is consumed in the non-sheet passing area. Since the heat is not removed from the fixing member, the temperature of the fixing member is excessively increased mainly in the non-sheet passing area at the widthwise end of the fixing member.

上記の課題に対して、特許文献1〜3では、ニップ部を形成するニップ形成部材又はその一部に高熱伝導部材を用いることで、温度上昇しやすい非通紙領域の熱を拡散させて過剰な温度上昇を抑制する手段が提案されている。   In order to solve the above-described problem, Patent Documents 1 to 3 disclose a nip forming member that forms a nip portion or a part of the nip forming member with a high heat conductive member, thereby diffusing heat in a non-paper passing region where temperature tends to increase, thereby causing excessive heat. Means for suppressing an excessive rise in temperature have been proposed.

前述した定着装置の場合、短時間で大量の枚数の記録媒体が定着装置に運ばれて定着動作が行われた場合、高熱伝導部材に熱が伝達し続け、高熱伝導部材が高温の状態で維持されてしまう。そして、高熱伝導部材が高温状態のまま定着動作が実行されることにより、高熱伝導部材が非通紙領域の熱を十分に拡散することができず、定着部材の端部における過剰な温度上昇を抑制できないという問題が発生する。   In the case of the above-described fixing device, when a large number of recording media are transported to the fixing device in a short time and the fixing operation is performed, heat is continuously transmitted to the high heat conductive member, and the high heat conductive member is maintained at a high temperature. Will be done. When the fixing operation is performed while the high heat conductive member is in a high temperature state, the high heat conductive member cannot sufficiently diffuse heat in the non-sheet passing area, and an excessive temperature rise at the end of the fixing member is prevented. The problem that it cannot be suppressed occurs.

この様な事情から、本発明では、高熱伝導部材の過剰な昇温を防止することのできる定着装置を提供することを課題としている。   Under such circumstances, an object of the present invention is to provide a fixing device that can prevent an excessive rise in temperature of a high heat conductive member.

上記の課題を解決するため、本発明は、回転可能な定着部材と、前記定着部材を加熱する加熱源と、前記定着部材に当接し、定着ニップを形成する加圧部材と、前記定着部材の内側に設けられたニップ形成部材と、前記ニップ形成部材と前記定着部材の間に配置され、前記ニップ形成部材よりも熱伝導率の高い部材によって形成される高熱伝導部材とを備えた定着装置において、前記高熱伝導部材に接触する接触姿勢と前記高熱伝導部材から離間する離間姿勢とを切り替え可能に設けられる放熱部材を有することを特徴とする。   In order to solve the above problems, the present invention provides a rotatable fixing member, a heating source for heating the fixing member, a pressing member that contacts the fixing member and forms a fixing nip, A fixing device comprising: a nip forming member provided on an inner side; and a high heat conductive member disposed between the nip forming member and the fixing member and having a higher thermal conductivity than the nip forming member. A heat radiating member provided so as to be switchable between a contact posture in contact with the high heat conduction member and a separation posture away from the high heat conduction member.

本発明では、高熱伝導部材に接触する接触姿勢と離間姿勢を切り替え可能な放熱部材を設ける。放熱部材の高熱伝導部材への接触により、高熱伝導部材に蓄積された熱が放熱部材へ伝達され、高熱伝導部材の過剰な昇温を防止できる。   In the present invention, a heat dissipating member that can switch between a contact posture and a separation posture in contact with the high heat conductive member is provided. When the heat dissipating member contacts the high heat conducting member, the heat accumulated in the high heat conducting member is transmitted to the heat dissipating member, and an excessive rise in the temperature of the high heat conducting member can be prevented.

画像形成装置の概略構成図である。FIG. 2 is a schematic configuration diagram of an image forming apparatus. 定着装置の概略構成図である。FIG. 2 is a schematic configuration diagram of a fixing device. 定着装置に設けられた各部材の配置を概念的に示した図である。FIG. 3 is a diagram conceptually showing an arrangement of each member provided in the fixing device. 本実施形態と異なる構成の定着装置の定着ベルトの温度分布を示す図である。FIG. 6 is a diagram illustrating a temperature distribution of a fixing belt of a fixing device having a configuration different from that of the present embodiment. 本実施形態と異なる構成の定着装置の定着ベルトの温度分布を示す図である。FIG. 6 is a diagram illustrating a temperature distribution of a fixing belt of a fixing device having a configuration different from that of the present embodiment. 本実施形態と異なる構成の定着装置の定着ベルトの温度分布を示す図である。FIG. 6 is a diagram illustrating a temperature distribution of a fixing belt of a fixing device having a configuration different from that of the present embodiment. 本実施形態と異なる構成の定着装置の定着ベルトの温度分布を示す図である。FIG. 6 is a diagram illustrating a temperature distribution of a fixing belt of a fixing device having a configuration different from that of the present embodiment. 本実施形態の定着装置の断面図である。FIG. 2 is a cross-sectional view of the fixing device according to the exemplary embodiment. 放熱部材の姿勢の切り替えを説明する断面図で、放熱部材が(a)図は離間姿勢に、(b)図は接触姿勢に配置されている。It is sectional drawing explaining switching of the attitude | position of a heat radiating member, and a heat radiating member is arrange | positioned at the separated attitude | position in FIG. 放熱フィンの斜視図である。It is a perspective view of a radiation fin. 放熱部材の姿勢切替機構を示す概略図で、(a)図が側面図、(b)図が平面図である。FIGS. 4A and 4B are schematic diagrams illustrating a posture switching mechanism of a heat radiating member, wherein FIG. 4A is a side view and FIG. 非印刷動作時の放熱部材の制御フローの一例を示す図である。FIG. 7 is a diagram illustrating an example of a control flow of a heat radiation member during a non-printing operation. 定着ベルトと加圧ローラの脱圧機構を設けた定着装置の脱圧状態を示す概念図である。FIG. 4 is a conceptual diagram illustrating a depressurized state of a fixing device provided with a depressurizing mechanism for a fixing belt and a pressure roller. 本実施形態と異なる構成の放熱部材の高熱伝導部材への接触状態を示す図である。It is a figure which shows the contact state of the heat radiation member of a structure different from this embodiment to a high heat conductive member. 異なる実施形態の定着装置を示す図である。FIG. 4 is a diagram illustrating a fixing device according to another embodiment. 本実施形態の変形例で、弾性部材を放熱部材に設けた図である。It is the figure which provided the elastic member in the heat dissipation member in the modification of this embodiment.

以下、本発明に係る実施の形態について、図面を参照して説明する。なお、各図中、同一又は相当する部分には同一の符号を付しており、その重複説明は適宜に簡略化ないし省略する。   Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the drawings, the same or corresponding portions are denoted by the same reference characters, and a repeated description thereof will be appropriately simplified or omitted.

図1に示すカラー画像形成装置1の中央には、4つのプロセスユニット9Y,9M,9C,9Bkが着脱可能に設けられた画像形成部2が配置されている。各プロセスユニット9Y,9M,9C,9Bkは、カラー画像の色分解成分に対応するイエロー(Y)、マゼンタ(M)、シアン(C)、ブラック(Bk)の異なる色の現像剤を収容している以外は同様の構成となっている。   In the center of the color image forming apparatus 1 shown in FIG. 1, an image forming unit 2 in which four process units 9Y, 9M, 9C, 9Bk are detachably provided is arranged. Each of the process units 9Y, 9M, 9C, and 9Bk stores developers of different colors of yellow (Y), magenta (M), cyan (C), and black (Bk) corresponding to color separation components of a color image. The configuration is the same except for the presence.

具体的な各プロセスユニット9としては、表面上に現像剤としてのトナーを担持可能なドラム状の回転体である感光体ドラム10と、感光体ドラム10の表面を一様に帯電させる帯電ローラ11と、感光体ドラム10の表面にトナーを供給する現像ローラ13を有する現像装置12等を備えている。   Specific process units 9 include a photosensitive drum 10 which is a drum-shaped rotating body capable of carrying toner as a developer on the surface thereof, and a charging roller 11 which uniformly charges the surface of the photosensitive drum 10. And a developing device 12 having a developing roller 13 for supplying toner to the surface of the photosensitive drum 10.

画像形成装置1の上部には、イエロー、シアン、マゼンタ、黒の各色トナーが充填されたトナーボトル26Y,C,M,Bkが着脱可能に設けられている。そして、このトナーボトル26Y,C,M,Bkから各現像装置12との間に設けた補給路を介して、各色の現像装置12に各色トナーが補給される。   At the top of the image forming apparatus 1, toner bottles 26Y, C, M, and Bk filled with yellow, cyan, magenta, and black toners are detachably provided. Then, toner of each color is supplied to the developing device 12 of each color via a supply path provided between the toner bottles 26Y, 26C, 26M, and Bk and each developing device 12.

プロセスユニット9の下方には、露光部3が配置されている。露光部3は、画像データに基づいて、レーザ光を発するように構成されている。   The exposure unit 3 is arranged below the process unit 9. The exposure unit 3 is configured to emit a laser beam based on image data.

画像形成部2の上方には転写部4が配置されている。転写部4は、駆動ローラ14及び従動ローラ15に周回走行可能に張架されている無端状の中間転写ベルト16、各プロセスユニット9の感光体ドラム10に対して中間転写ベルト16を挟んだ対向位置に配置されている一次転写ローラ17等で構成されている。各一次転写ローラ17はそれぞれの位置で中間転写ベルト16の内周面を押圧しており、中間転写ベルト16の押圧された部分と各感光体ドラム10とが接触する箇所に一次転写ニップが形成されている。   A transfer unit 4 is disposed above the image forming unit 2. The transfer unit 4 is an endless intermediate transfer belt 16 that is stretched around a drive roller 14 and a driven roller 15 so as to be able to travel around. The transfer unit 4 faces the photosensitive drum 10 of each process unit 9 with the intermediate transfer belt 16 interposed therebetween. It is composed of a primary transfer roller 17 and the like arranged at the position. Each primary transfer roller 17 presses the inner peripheral surface of the intermediate transfer belt 16 at each position, and a primary transfer nip is formed at a position where the pressed portion of the intermediate transfer belt 16 and each photosensitive drum 10 come into contact. Have been.

また、中間転写ベルト16の駆動ローラ14と、中間転写ベルト16を挟んで駆動ローラ14に対向した位置には二次転写ローラ18が配設されている。二次転写ローラ18は中間転写ベルト16の外周面を押圧しており、二次転写ローラ18と中間転写ベルト16とが接触する箇所に二次転写ニップが形成されている。   Further, a driving roller 14 of the intermediate transfer belt 16 and a secondary transfer roller 18 are disposed at a position facing the driving roller 14 with the intermediate transfer belt 16 interposed therebetween. The secondary transfer roller 18 presses the outer peripheral surface of the intermediate transfer belt 16, and a secondary transfer nip is formed at a position where the secondary transfer roller 18 contacts the intermediate transfer belt 16.

給紙部5は、画像形成装置1の下部に位置しており、記録媒体としての用紙Pを収容した給紙カセット19や、給紙カセット19から用紙Pを搬出する給紙ローラ20等からなっている。   The paper supply unit 5 is located below the image forming apparatus 1 and includes a paper supply cassette 19 that stores paper P as a recording medium, a paper supply roller 20 that carries out the paper P from the paper supply cassette 19, and the like. ing.

搬送路6は、給紙部5から搬出された用紙Pを搬送する搬送経路であり、一対のレジストローラ21の他、後述する排紙部8に至るまで、搬送ローラ対が搬送路6の途中に適宜配置されている。   The transport path 6 is a transport path for transporting the sheet P unloaded from the paper feed unit 5. The transport roller pair is located in the middle of the transport path 6, in addition to the pair of registration rollers 21, to a paper discharge unit 8 described below. Are arranged as appropriate.

定着装置7は、加熱源によって加熱される定着部材としての定着ベルト30、その定着ベルト30を加圧可能な、加圧部材としての加圧ローラ31等を有している。   The fixing device 7 has a fixing belt 30 as a fixing member heated by a heating source, a pressure roller 31 as a pressing member capable of pressing the fixing belt 30, and the like.

排紙部8は、画像形成装置1の搬送路6の最下流に設けられる。この排紙部8には、用紙Pを外部へ排出するための一対の排紙ローラ24と、排出された用紙Pをストックするための排紙トレイ25とが配設されている。   The paper discharge unit 8 is provided at the most downstream of the transport path 6 of the image forming apparatus 1. The paper discharge section 8 is provided with a pair of paper discharge rollers 24 for discharging the paper P to the outside and a paper discharge tray 25 for stocking the discharged paper P.

以下、図1を参照して上記画像形成装置1の基本的動作について説明する。   Hereinafter, a basic operation of the image forming apparatus 1 will be described with reference to FIG.

画像形成装置1において、画像形成動作が開始されると、各プロセスユニット9Y,9C,9M,9Bkの感光体ドラム10の表面に静電潜像が形成される。各感光体ドラム10に露光部3によって露光される画像情報は、所望のフルカラー画像をイエロー、シアン、マゼンタ及びブラックの色情報に分解した単色の画像情報である。各感光体ドラム10上には静電潜像が形成され、各現像装置12に蓄えられたトナーが、ドラム状の現像ローラ13によって感光体ドラム10に供給されることにより、静電潜像は顕像であるトナー画像(現像剤像)として可視像化される。   When the image forming operation is started in the image forming apparatus 1, an electrostatic latent image is formed on the surface of the photosensitive drum 10 of each of the process units 9Y, 9C, 9M, and 9Bk. The image information exposed on each photosensitive drum 10 by the exposure unit 3 is monochromatic image information obtained by decomposing a desired full-color image into yellow, cyan, magenta, and black color information. An electrostatic latent image is formed on each photoconductor drum 10, and the toner stored in each developing device 12 is supplied to the photoconductor drum 10 by a drum-shaped developing roller 13, whereby the electrostatic latent image is formed. This is visualized as a visible toner image (developer image).

転写部4では、駆動ローラ14の回転駆動により中間転写ベルト16が図の矢印Aの方向に走行駆動される。また、各一次転写ローラ17には、トナーの帯電極性と逆極性の定電圧又は定電流制御された電圧が印加される。これにより、一次転写ニップにおいて転写電界が形成され、各感光体ドラム10に形成されたトナー画像は一次転写ニップにて中間転写ベルト16上に順次重ね合わせて転写される。   In the transfer section 4, the intermediate transfer belt 16 is driven to run in the direction of arrow A in FIG. Further, to each of the primary transfer rollers 17, a constant voltage having a polarity opposite to the charging polarity of the toner or a voltage controlled with a constant current is applied. As a result, a transfer electric field is formed in the primary transfer nip, and the toner images formed on the respective photosensitive drums 10 are sequentially transferred onto the intermediate transfer belt 16 in the primary transfer nip.

一方、画像形成動作が開始されると、画像形成装置1の下部では、給紙部5の給紙ローラ20が回転駆動することによって、給紙カセット19に収容された用紙Pが搬送路6に送り出される。搬送路6に送り出された用紙Pは、レジストローラ21によってタイミングを計られて、二次転写ローラ18と駆動ローラ14との間の二次転写ニップに送られる。このとき、中間転写ベルト16上のトナー画像のトナー帯電極性と逆極性の転写電圧が印加されており、二次転写ニップに転写電界が形成されている。二次転写ニップに形成された転写電界によって、中間転写ベルト16上のトナー画像が用紙P上に一括して転写される。   On the other hand, when the image forming operation is started, in the lower part of the image forming apparatus 1, the paper P stored in the paper feed cassette 19 is moved to the transport path 6 by rotating the paper feed roller 20 of the paper feed unit 5. Will be sent out. The sheet P sent out to the conveyance path 6 is sent to a secondary transfer nip between the secondary transfer roller 18 and the drive roller 14 at timing by the registration roller 21. At this time, a transfer voltage having a polarity opposite to the toner charge polarity of the toner image on the intermediate transfer belt 16 is applied, and a transfer electric field is formed in the secondary transfer nip. By the transfer electric field formed in the secondary transfer nip, the toner images on the intermediate transfer belt 16 are collectively transferred onto the paper P.

トナー画像が転写された用紙Pは、定着装置7へと搬送され、定着ベルト30と加圧ローラ31とによって用紙Pが加熱及び加圧されてトナー画像が用紙Pに定着される。そして、トナー画像が定着された用紙Pは、定着ベルト30から分離され、搬送ローラ対によって搬送され、排紙部8において排紙ローラ24によって排紙トレイ25へと排出される。   The sheet P to which the toner image has been transferred is conveyed to the fixing device 7, and the sheet P is heated and pressed by the fixing belt 30 and the pressure roller 31, so that the toner image is fixed on the sheet P. Then, the sheet P on which the toner image is fixed is separated from the fixing belt 30, conveyed by a pair of conveying rollers, and discharged to a discharge tray 25 by a discharge roller 24 in a discharge section 8.

以上の説明は、用紙P上にフルカラー画像を形成するときの画像形成動作であるが、4つのプロセスユニット9Y,9C,9M,9Bkのいずれか1つを使用して単色画像を形成したり、2つ又は3つのプロセスユニット9を使用して、2色又は3色の画像を形成したりすることも可能である。   The above description is an image forming operation when forming a full-color image on the paper P. A single-color image is formed using any one of the four process units 9Y, 9C, 9M, and 9Bk. It is also possible to form a two-color or three-color image using two or three process units 9.

次に本実施形態の定着装置7について、その構成を具体的に説明する。図2に示すように、定着装置7は、回転可能な定着ベルト30と、定着ベルト30に対向して配置される加圧部材としての加圧ローラ31と、加熱源としてのハロゲンヒータ32と、温度検知機構29等が設けられる。   Next, the configuration of the fixing device 7 of the present embodiment will be specifically described. As shown in FIG. 2, the fixing device 7 includes a rotatable fixing belt 30, a pressing roller 31 as a pressing member disposed to face the fixing belt 30, a halogen heater 32 as a heating source, A temperature detection mechanism 29 and the like are provided.

ハロゲンヒータ32は、定着ベルト30の幅方向端部側を加熱する端部ヒータ23aと、幅方向中央側を加熱する中央ヒータ23bとからなる。ただし、ヒータが1本のみの構成であってもよいし、3本以上であってもよい。   The halogen heater 32 includes an end heater 23a for heating the end portion in the width direction of the fixing belt 30 and a central heater 23b for heating the center side in the width direction. However, the configuration may include only one heater, or may include three or more heaters.

定着ベルト30の内側には、定着ベルト30を介して加圧ローラ31との間でニップNを形成するニップ形成部材33と、定着ベルト30とニップ形成部材33の間に設けられる高熱伝導部材34と、ニップ形成部材33をニップNの反対側から支持するステー35と、ハロゲンヒータ32からの輻射熱を反射する反射部材36等が設けられる。   Inside the fixing belt 30, a nip forming member 33 that forms a nip N with the pressure roller 31 via the fixing belt 30, and a high heat conductive member 34 provided between the fixing belt 30 and the nip forming member 33. And a stay 35 for supporting the nip forming member 33 from the opposite side of the nip N, a reflecting member 36 for reflecting the radiant heat from the halogen heater 32, and the like.

定着ベルト30は、ニッケルやSUSなどの金属ベルトやポリイミドなどの樹脂材料を用いた無端ベルトまたはフィルムで構成される。ベルトの表層はPFAまたはPTFE層などの離型層を有し、トナーが付着しないように離型性を持たせている。ベルトの基材とPFAまたはPTFE層の間にはシリコーンゴムの層などで形成された弾性層を設けても良い。シリコーンゴム層がない場合は熱容量が小さくなり、定着性が向上するが、未定着画像を押し潰して定着させるときにベルト表面の微小な凹凸が画像に転写されて画像のベタ部にユズ肌状の光沢ムラ(ユズ肌画像)が残るという不具合が生じ得る。これを改善するにはシリコーンゴム層を100[μm]以上設ける必要がある。シリコーンゴム層の変形により、微小な凹凸が吸収されユズ肌画像が改善する。   The fixing belt 30 is formed of a metal belt such as nickel or SUS, or an endless belt or film using a resin material such as polyimide. The surface layer of the belt has a release layer such as a PFA or PTFE layer, and has a release property so that toner does not adhere. An elastic layer formed of a silicone rubber layer or the like may be provided between the base material of the belt and the PFA or PTFE layer. If there is no silicone rubber layer, the heat capacity will be small and the fixability will be improved.However, when the unfixed image is crushed and fixed, the minute irregularities on the belt surface will be transferred to the image, and the solid part of the image will have a scumming appearance. A problem may occur in that uneven glossiness (yuzu skin image) remains. To improve this, it is necessary to provide a silicone rubber layer of 100 [μm] or more. Due to the deformation of the silicone rubber layer, minute unevenness is absorbed, and the yuzu skin image is improved.

温度検知機構29は、定着ベルト30を挟んでハロゲンヒータ32に対向して設けられ、ハロゲンヒータ32によって加熱された定着ベルト30表面の幅方向端部の温度を検知する。この温度検知機構29によって検知された定着ベルト30の温度に基づいて、ハロゲンヒータ32の加熱量を制御し、定着ベルト30表面の温度を定着動作に必要な温度に調整することができる。   The temperature detection mechanism 29 is provided to face the halogen heater 32 with the fixing belt 30 interposed therebetween, and detects the temperature of the edge in the width direction of the surface of the fixing belt 30 heated by the halogen heater 32. The heating amount of the halogen heater 32 is controlled based on the temperature of the fixing belt 30 detected by the temperature detecting mechanism 29, and the temperature of the surface of the fixing belt 30 can be adjusted to a temperature required for the fixing operation.

加圧ローラ31は、芯金311の外側に弾性のゴム層312、さらに外周面の側には離型性を得るために離型層(PFAまたはPTFE層)が設けてある。加圧ローラ31は、画像形成装置に設けられたモータなどの駆動源からギヤを介して駆動力が伝達され回転する。また、加圧ローラ31は、スプリングなどにより定着ベルト30側に押し付けられており、弾性ゴム層312が押し潰されて変形することにより、所定のニップ幅を有している。加圧ローラ31は中空のローラであっても良く、加圧ローラ31にハロゲンヒータなどの加熱源を設けることもできる。弾性ゴム層312はソリッドゴムでも良いが、加圧ローラ31内部にヒータが無い場合は、スポンジゴムを用いても良い。スポンジゴムの方が、断熱性が高まり定着ベルト30の熱が奪われにくくなるので、より望ましい。   The pressure roller 31 is provided with an elastic rubber layer 312 outside the cored bar 311 and a release layer (PFA or PTFE layer) on the outer peripheral surface side in order to obtain releasability. The pressing roller 31 is rotated by a driving force transmitted from a driving source such as a motor provided in the image forming apparatus via a gear. Further, the pressure roller 31 is pressed against the fixing belt 30 by a spring or the like, and has a predetermined nip width as the elastic rubber layer 312 is crushed and deformed. The pressure roller 31 may be a hollow roller, and the pressure roller 31 may be provided with a heating source such as a halogen heater. The elastic rubber layer 312 may be solid rubber, but if there is no heater inside the pressure roller 31, sponge rubber may be used. Sponge rubber is more preferable because heat insulation is enhanced and heat of the fixing belt 30 is hardly deprived.

定着ベルト30は、加圧ローラ31の回転により、定着ニップNにおいて加圧ローラ31の回転力が伝達され、加圧ローラ31に従動回転する。定着ベルト30は、ハロゲンヒータ32によって加熱されており、定着ニップNにおいて、通紙される用紙Pおよびその表面に形成されたトナー画像に熱を伝達すると共に、用紙Pを加圧し、トナー画像を用紙Pに定着させる。定着ニップNは平坦面によって形成されるが、一部が凹形状や凸形状であってもよい。   Due to the rotation of the pressure roller 31, the rotation of the pressure roller 31 is transmitted to the fixing belt 30 at the fixing nip N, and the fixing belt 30 is driven to rotate by the pressure roller 31. The fixing belt 30 is heated by the halogen heater 32, and transfers heat to the paper P to be passed and the toner image formed on the surface thereof, and presses the paper P to fix the toner image at the fixing nip N. The image is fixed on the paper P. The fixing nip N is formed by a flat surface, but may be partially concave or convex.

ニップ形成部材33は、耐熱温度200℃以上の耐熱性部材で構成されている。これにより、トナー定着温度域で、熱によるニップ形成部材33の変形を防止し、安定した定着ニップNの状態を確保して、出力画質の安定化を図っている。ニップ形成部材33には、ポリエーテルサルフォン(PES)、ポリフェニレンスルフィド(PPS)、液晶ポリマー(LCP)、ポリエーテルニトリル(PEN)、ポリアミドイミド(PAI)、ポリエーテルエーテルケトン(PEEK)などの一般的な耐熱性樹脂を用いることが可能である。   The nip forming member 33 is formed of a heat-resistant member having a heat-resistant temperature of 200 ° C. or higher. This prevents deformation of the nip forming member 33 due to heat in the toner fixing temperature range, secures a stable fixing nip N state, and stabilizes the output image quality. The nip forming member 33 includes a general material such as polyether sulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether nitrile (PEN), polyamide imide (PAI), polyether ether ketone (PEEK), and the like. It is possible to use a suitable heat-resistant resin.

また、ニップ形成部材33の表面に低摩擦シートを設けてもよい。これにより、定着ベルト30の回転時に、定着ベルト30とニップ形成部材33の摺接により発生する摩擦力を軽減し、加圧ローラ31の駆動トルクを低減することができる。   Further, a low friction sheet may be provided on the surface of the nip forming member 33. Thereby, when the fixing belt 30 rotates, the frictional force generated by the sliding contact between the fixing belt 30 and the nip forming member 33 can be reduced, and the driving torque of the pressure roller 31 can be reduced.

定着ニップNの定着ベルト30の長手方向の温度分布を均一にするため、ニップ形成部材33のニップ部N側の表面には高熱伝導部材34が設けられている。高熱伝導部材34は、例えば、銅やアルミニウム等の熱伝導率の大きい金属板からなり、その熱伝導率はニップ形成部材33よりも大きく設定される。具体的には、高熱伝導部材34の熱伝導率は、236W/(m・K)以上に設定されることが好ましい。高熱伝導部材34の厚みは適宜選択することができるが、例えば、0.3〜0.5mmとすることができる。   In order to make the temperature distribution of the fixing nip N in the longitudinal direction of the fixing belt 30 uniform, a high heat conductive member 34 is provided on the surface of the nip forming member 33 on the nip portion N side. The high heat conductive member 34 is made of, for example, a metal plate having a high thermal conductivity such as copper or aluminum, and the thermal conductivity is set to be higher than that of the nip forming member 33. Specifically, the thermal conductivity of the high thermal conductive member 34 is preferably set to 236 W / (m · K) or more. Although the thickness of the high heat conductive member 34 can be appropriately selected, it can be, for example, 0.3 to 0.5 mm.

ステー35は、定着ニップNにおいて加圧ローラ31より圧力を受けるニップ形成部材33を、定着ニップNの反対側から支持する。これにより、ニップ形成部材33の撓みを防止し、軸方向で均一なニップ幅が得られるようにしている。ステー35は、ステンレスや鉄、アルミ等の金属からなる。   The stay 35 supports the nip forming member 33 that receives pressure from the pressure roller 31 in the fixing nip N from the side opposite to the fixing nip N. Thus, the nip forming member 33 is prevented from bending, and a uniform nip width is obtained in the axial direction. The stay 35 is made of a metal such as stainless steel, iron, or aluminum.

ステー35は、その幅方向(図2の紙面手前奥方向)両端部でフランジによって保持固定され、位置決めされている。定着ベルト30は、このフランジによってその幅方向両端でガイドされ、加圧ローラ31に従動回転する。   The stay 35 is held and fixed by flanges at both ends in the width direction (forward and backward direction in FIG. 2) and is positioned. The fixing belt 30 is guided at both ends in the width direction by the flange, and is driven to rotate by the pressure roller 31.

ステー35とハロゲンヒータ32の間には反射部材36が設けられる。反射部材36は、アルミ基材の表面に銀等をコーティングして形成されるが、その材料はこれに限るものではない。   A reflection member 36 is provided between the stay 35 and the halogen heater 32. The reflection member 36 is formed by coating the surface of an aluminum base material with silver or the like, but the material is not limited to this.

反射部材36は、ハロゲンヒータ32からステー35の側へ流れる輻射熱を定着ベルト30の側へ反射する。これにより、無駄なエネルギー消費を抑制し、定着ベルト30を効率良く加熱することができる。反射部材36を設ける代わりに、ステー35の表面に断熱処理や鏡面処理を施し、ステー35がハロゲンヒータ32からの輻射熱を反射するようにしてもよい。   The reflecting member 36 reflects the radiant heat flowing from the halogen heater 32 toward the stay 35 toward the fixing belt 30. Thus, wasteful energy consumption can be suppressed, and the fixing belt 30 can be efficiently heated. Instead of providing the reflecting member 36, the surface of the stay 35 may be subjected to a heat insulation treatment or a mirror surface treatment so that the stay 35 reflects the radiant heat from the halogen heater 32.

図3は、定着装置に設けられた各部材の配置を概念的に示したものである。ただし、温度検知機構29や後述する放熱部材等は記載されていない。なお、以下、定着ベルト30の幅方向(図3の上下方向)端部側を幅方向の外側、定着ベルト30の幅方向中央側を幅方向の内側と呼ぶ。   FIG. 3 conceptually shows the arrangement of each member provided in the fixing device. However, the temperature detecting mechanism 29 and a heat radiating member described later are not described. Hereinafter, the end side in the width direction (vertical direction in FIG. 3) of the fixing belt 30 is referred to as the outside in the width direction, and the center side in the width direction of the fixing belt 30 is referred to as the inside in the width direction.

ニップ形成部材33および高熱伝導部材34は、定着ベルト30の幅方向にわたって、定着ベルト30に対向して設けられている。高熱伝導部材34が、定着ベルト30の幅方向にわたって設けられることにより、加熱された定着ベルト30の熱を幅方向に伝達させ、定着ベルト30の幅方向の温度ムラを減らすことができる。   The nip forming member 33 and the high heat conductive member 34 are provided to face the fixing belt 30 across the width direction of the fixing belt 30. By providing the high thermal conductive member 34 over the width direction of the fixing belt 30, the heat of the heated fixing belt 30 is transmitted in the width direction, and the temperature unevenness of the fixing belt 30 in the width direction can be reduced.

図4〜図6は、大サイズの用紙P1あるいは小サイズの用紙P2を定着装置7に通紙した場合の、温度検知機構29により検知される定着ベルト30の幅方向の温度分布を示すものであり、本実施形態とは異なる構成の定着装置を示すものである。具体的には、図4〜図6には後述する放熱部材は設けられておらず、図4および図5は高熱伝導部材34が設けられていない。これらの構成における定着ベルト30の温度分布を示すことにより、本実施形態が解決する課題について説明する。   4 to 6 show the temperature distribution in the width direction of the fixing belt 30 detected by the temperature detecting mechanism 29 when the large-size paper P1 or the small-size paper P2 is passed through the fixing device 7. This shows a fixing device having a configuration different from that of the present embodiment. Specifically, FIGS. 4 to 6 do not include a heat dissipating member described later, and FIGS. 4 and 5 do not include the high heat conducting member 34. The problem solved by the present embodiment will be described by showing the temperature distribution of the fixing belt 30 in these configurations.

図4に示すように、定着ベルト30の幅方向の温度Tは、用紙Pの表面の画像を定着させるために適当な目標温度T1になるようにハロゲンヒータ32によって加熱されている。そして、ハロゲンヒータ32の加熱幅Bと同じ幅の用紙P1が定着装置7に通紙された場合には、定着ベルト30の全幅にわたって、定着ベルト30から用紙P1へ熱が伝達され、定着ベルト30の幅方向の温度ムラはほとんど生じない。   As shown in FIG. 4, the temperature T in the width direction of the fixing belt 30 is heated by the halogen heater 32 so as to reach a target temperature T1 appropriate for fixing an image on the surface of the sheet P. When the sheet P1 having the same width as the heating width B of the halogen heater 32 is passed through the fixing device 7, heat is transmitted from the fixing belt 30 to the sheet P1 over the entire width of the fixing belt 30, and Temperature unevenness in the width direction hardly occurs.

一方で、図5に示すように、ハロゲンヒータ32の加熱幅Bよりも幅の小さい小サイズの用紙P2が通紙された場合には、定着ベルト30の幅方向端部の非通紙領域において、ハロゲンヒータ32から受けた熱が用紙P2へ伝達されず、目標温度T1を超えて温度が過剰に上昇してしまう。   On the other hand, as shown in FIG. 5, when a small-sized sheet P2 having a width smaller than the heating width B of the halogen heater 32 is passed, the fixing belt 30 is not moved in the non-sheet passing area at the widthwise end. However, the heat received from the halogen heater 32 is not transmitted to the sheet P2, and the temperature excessively rises above the target temperature T1.

上記のいわゆる端部温度上昇を緩和するために、高熱伝導部材34が設けられる。つまり、図6に示すように、高熱伝導部材34を定着ベルト30の幅方向にわたって設けることにより、定着ベルト30の幅方向の熱移動を促進し、定着ベルト30の幅方向の温度分布を均一化することで、定着ベルト30の幅方向端部の温度が過剰に上昇することを防止できる。   In order to mitigate the above-mentioned so-called end temperature rise, a high heat conductive member 34 is provided. That is, as shown in FIG. 6, by providing the high heat conductive member 34 over the width direction of the fixing belt 30, heat transfer in the width direction of the fixing belt 30 is promoted, and the temperature distribution in the width direction of the fixing belt 30 is made uniform. By doing so, it is possible to prevent the temperature at the end in the width direction of the fixing belt 30 from excessively increasing.

しかし、上記の高熱伝導部材34を設けた場合でも、定着ベルト30の端部温度上昇の問題が発生する場合がある。つまり、短時間で大量の枚数の小サイズ用紙が定着装置7に運ばれて定着動作が行われた場合、その間に高熱伝導部材34に熱が伝達し続け、高熱伝導部材34が高温の状態で維持されてしまう。そして、高熱伝導部材34が高温状態のまま定着動作が実行されると、高熱伝導部材34が非通紙領域の熱を十分に拡散することができず、定着ベルト30の端部における過剰な温度上昇を抑制できなくなってしまう。これにより、図7に示すように、高熱伝導部材34を設けた場合でも、定着ベルト30の幅方向端部における過剰な温度上昇が発生してしまう。   However, even when the above-described high heat conductive member 34 is provided, a problem of an increase in the temperature at the end of the fixing belt 30 may occur. In other words, when a large number of small-sized papers are conveyed to the fixing device 7 in a short time and the fixing operation is performed, heat continues to be transmitted to the high heat conductive member 34 during that time, and the high heat conductive member 34 is in a high temperature state. Will be maintained. If the fixing operation is performed while the high heat conductive member 34 is in a high temperature state, the high heat conductive member 34 cannot sufficiently diffuse the heat in the non-sheet passing area, and the excessive temperature at the end of the fixing belt 30 The rise cannot be suppressed. As a result, as shown in FIG. 7, even when the high heat conductive member 34 is provided, an excessive temperature rise at the widthwise end of the fixing belt 30 occurs.

上記の課題に対して、本実施形態では、放熱部材を設けることにより、高熱伝導部材34の高温状態を緩和することができる。以下、この放熱部材について図8を用いて説明する。   In order to solve the above problem, in the present embodiment, the provision of the heat radiating member can ease the high temperature state of the high heat conducting member 34. Hereinafter, this heat radiating member will be described with reference to FIG.

図8に示すように、本実施形態の定着装置7には、定着ベルト30の幅方向両端の外側に、放熱部材37が設けられる。放熱部材37は、定着ベルト30の幅方向に移動可能に設けられており、この幅方向の移動により、高熱伝導部材34から離間した離間姿勢(図9(a)参照)と高熱伝導部材34(およびニップ形成部材33)に接触する接触姿勢(図9(b)参照)とを切り替え可能に設けられる。   As shown in FIG. 8, in the fixing device 7 of the present embodiment, heat radiating members 37 are provided outside both ends of the fixing belt 30 in the width direction. The heat radiating member 37 is provided so as to be movable in the width direction of the fixing belt 30, and by moving in the width direction, the heat radiating member 37 is separated from the high heat conductive member 34 (see FIG. 9A) and the high heat conductive member 34 ( And a contact posture (see FIG. 9B) in contact with the nip forming member 33).

放熱部材37は、接触姿勢で、高熱伝導部材34の幅方向端部に接触し、高熱伝導部材34の熱を放熱部材37の側へ逃がすことができる。これにより、高熱伝導部材34が高温状態となることを防止でき、短時間で大量の枚数の小サイズ用紙が定着装置7に運ばれて定着動作が行われたような場合であっても、高熱伝導部材34による定着ベルト30の幅方向の熱の伝達効果を維持し、図6で示した様な定着ベルト30の幅方向にムラのない温度分布を実現することが可能になる。特に、本実施形態の様に、放熱部材37を高熱伝導部材34の幅方向端部に接触させることにより、図7に示したような高熱伝導部材34の幅方向端部の高温状態をより確実に防止し、図6の様なムラのない温度分布により確実に近づけることができる。   The heat dissipating member 37 contacts the width direction end of the high heat conducting member 34 in the contact posture, and can release the heat of the high heat conducting member 34 to the heat dissipating member 37 side. This can prevent the high heat conductive member 34 from being brought to a high temperature state. Even when a large number of small-sized sheets are conveyed to the fixing device 7 in a short time and the fixing operation is performed, The heat transfer effect of the conductive member 34 in the width direction of the fixing belt 30 is maintained, and a uniform temperature distribution in the width direction of the fixing belt 30 as shown in FIG. 6 can be realized. In particular, by contacting the heat radiating member 37 to the width direction end of the high heat conduction member 34 as in the present embodiment, the high temperature state of the width direction end of the high heat conduction member 34 as shown in FIG. And the temperature can be reliably approached by a uniform temperature distribution as shown in FIG.

図10に放熱部材37の一例として、放熱フィンの形状を示す。放熱部材37は、ベース371とベース371から突出して設けられた複数のフィン372からなる。放熱部材37は、複数のフィン372を有することにより、その表面積を増大させ、高熱伝導部材34から伝達された熱を外気中へ効率良く放出することができる。   FIG. 10 shows the shape of a heat radiation fin as an example of the heat radiation member 37. The heat radiation member 37 includes a base 371 and a plurality of fins 372 provided to protrude from the base 371. Since the heat dissipating member 37 has the plurality of fins 372, the surface area thereof can be increased, and the heat transmitted from the high heat conducting member 34 can be efficiently released to the outside air.

本実施形態の放熱部材37として、銅やアルミニウム等の熱伝導率の高い材料を選択することができる。放熱部材37の熱伝導率は、高熱伝導部材34から放熱部材37への熱の伝達を効率良く行うために、高熱伝導部材34の熱伝導率と同等以上に設定されることが好ましい。   As the heat radiation member 37 of the present embodiment, a material having high thermal conductivity such as copper or aluminum can be selected. The heat conductivity of the heat radiating member 37 is preferably set to be equal to or higher than the heat conductivity of the high heat conducting member 34 in order to efficiently transfer heat from the high heat conducting member 34 to the heat radiating member 37.

放熱部材37の姿勢を切り替える姿勢切替機構は、一例としてカムを利用した図11の構成を用いることができる。図11(a)および図11(b)に示すように、モータ38と、モータ38に連結された回転軸381と、カム39と、バネ40が設けられる。   As an example of the attitude switching mechanism for switching the attitude of the heat radiation member 37, the configuration shown in FIG. 11 using a cam can be used. As shown in FIGS. 11A and 11B, a motor 38, a rotating shaft 381 connected to the motor 38, a cam 39, and a spring 40 are provided.

バネ40は、その一端が放熱部材37に接続され、他端が画像形成装置の筐体等に固定されており、放熱部材37を矢印C1の方向へ付勢している。また、カム39は、その一方側で放熱部材37に当接しており、他方側でギヤ部391が回転軸381と噛み合っている。放熱部材37は、バネ40から付勢されて矢印C1の方向へ移動し、カム39に当接している。なお、放熱部材37を矢印C1の方向へ付勢できるように適宜配置すればよく、図11(a)では、便宜上、カム39と重ねて点線で表示し、図11(b)には表示していない。   One end of the spring 40 is connected to the heat radiating member 37, and the other end is fixed to a housing or the like of the image forming apparatus, and urges the heat radiating member 37 in the direction of arrow C <b> 1. The cam 39 contacts the heat radiation member 37 on one side, and the gear portion 391 meshes with the rotating shaft 381 on the other side. The heat radiating member 37 is urged by the spring 40 to move in the direction of the arrow C <b> 1, and is in contact with the cam 39. Note that the heat radiating member 37 may be appropriately disposed so as to be able to be urged in the direction of the arrow C1. For convenience, in FIG. Not.

モータ38の駆動により、回転軸381が回転すると、回転軸381と噛み合うカム39は、回転軸381から駆動力を伝達されて従動回転する。カム39の回転により、カム39に当接する放熱部材37が図11(a)の左右方向(定着ベルト30の幅方向)に移動する。具体的には、カム39の放熱部材37に対する当接位置の径が大きくなっていくことで、放熱部材37はバネ40の付勢力に抗して図11(a)の右方向へ移動し、高熱伝導部材34に接触する接触姿勢に切り替わる。また、カム39の放熱部材37に対する当接位置の径が小さくなっていくことで、カム39から放熱部材37に対する図11(a)の右方向への押圧状態が解除される。これにより、放熱部材37は、バネ40の付勢力によって左方向へ移動し、高熱伝導部材34から離間する離間姿勢に切り替わる。   When the rotation shaft 381 is rotated by the drive of the motor 38, the cam 39 meshing with the rotation shaft 381 is driven by the driving force transmitted from the rotation shaft 381 to rotate. By the rotation of the cam 39, the heat dissipating member 37 that contacts the cam 39 moves in the left-right direction (the width direction of the fixing belt 30) in FIG. Specifically, as the diameter of the contact position of the cam 39 with the heat radiating member 37 increases, the heat radiating member 37 moves rightward in FIG. 11A against the urging force of the spring 40, The posture is switched to the contact posture in contact with the high thermal conductive member 34. In addition, as the diameter of the contact position of the cam 39 with respect to the heat radiating member 37 decreases, the pressed state of the cam 39 with respect to the heat radiating member 37 in the rightward direction in FIG. 11A is released. As a result, the heat radiating member 37 is moved leftward by the urging force of the spring 40, and is switched to the separated position separated from the high heat conductive member 34.

放熱部材37を接触姿勢に配置し、高熱伝導部材34に蓄えられた熱を放出するタイミングとして、例えば、定着装置7の定着動作時以外(あるいは、画像形成装置の画像形成動作時以外)に行うことができる。   The heat radiating member 37 is arranged in the contact posture, and the timing at which the heat stored in the high heat conducting member 34 is released is, for example, other than the fixing operation of the fixing device 7 (or other than the image forming operation of the image forming apparatus). be able to.

放熱部材37を高熱伝導部材34に接触させることで、定着ベルト30の端部温度上昇の問題を解決することができるが、一方で、定着ベルト30に蓄えられた熱が、高熱伝導部材34を介して放熱部材37へ過剰に流出し、定着動作を行うために必要な目標温度T1を下回ってしまう可能性がある。しかし、上記の様に定着動作時以外に放熱部材37を接触姿勢とすることで、定着動作に影響を及ぼすことなく、高熱伝導部材34の高温状態を緩和することができる。   By bringing the heat dissipating member 37 into contact with the high thermal conductive member 34, the problem of the temperature rise at the end of the fixing belt 30 can be solved. On the other hand, the heat stored in the fixing belt 30 causes the high thermal conductive member 34 to There is a possibility that the toner may excessively flow out to the heat radiating member 37 and fall below the target temperature T1 required for performing the fixing operation. However, by setting the heat dissipating member 37 to the contact posture other than during the fixing operation as described above, the high-temperature state of the high heat conductive member 34 can be relaxed without affecting the fixing operation.

上記の様に、非画像形成時のみ放熱部材37を接触姿勢とする場合の、非画像形成時(非印刷動作時)の制御フローの一例を図12に示す。   FIG. 12 shows an example of a control flow at the time of non-image formation (at the time of non-printing operation) in the case where the heat radiating member 37 is in the contact posture only at the time of non-image formation as described above.

まず、印刷動作が終了すると(ステップS1)、温度検知機構29により検知される定着ベルト30の表面温度Tが、所定の温度T2を上回るか否かの判断を行う(ステップS2)。   First, when the printing operation is completed (Step S1), it is determined whether or not the surface temperature T of the fixing belt 30 detected by the temperature detecting mechanism 29 exceeds a predetermined temperature T2 (Step S2).

定着ベルト30の表面温度Tが温度T2を上回っている場合には、高熱伝導部材34による定着ベルト30の幅方向の熱の伝達が十分に行われていない、言い換えると、高熱伝導部材34が高温状態にある、と判断して、放熱部材37を接触姿勢に切り替え(ステップS3)、高熱伝導部材34に蓄えられた熱を放熱部材37の側へ伝達させる。   When the surface temperature T of the fixing belt 30 is higher than the temperature T2, the heat transfer in the width direction of the fixing belt 30 by the high heat conductive member 34 is not sufficiently performed. In other words, the high heat conductive member 34 When the state is determined to be in the state, the heat radiating member 37 is switched to the contact posture (step S3), and the heat stored in the high heat conductive member 34 is transmitted to the heat radiating member 37 side.

そして、画像形成装置1に再び印刷動作の信号が出された場合には(ステップS4)、放熱部材37が接触姿勢にあるか否かの判断を行う(ステップS5)。放熱部材37が接触姿勢に配置されている場合には、放熱部材37を離間姿勢に切り替える(ステップS6)。以上により、放熱部材37を離間姿勢に配置した状態で、印刷動作(定着動作)を開始することができる(ステップS7)。   Then, when the signal of the printing operation is output again to the image forming apparatus 1 (step S4), it is determined whether the heat radiation member 37 is in the contact posture (step S5). When the heat radiating member 37 is arranged in the contact posture, the heat radiating member 37 is switched to the separated posture (step S6). As described above, the printing operation (fixing operation) can be started in a state where the heat radiation member 37 is arranged in the separated posture (step S7).

また、これとは逆に、定着動作時に放熱部材37を接触姿勢に配置する構成とすることもできる。この場合、定着ベルト30が上記の様に目標温度T1を下回ることを防止するために、定着ベルト30の表面温度Tに基づいて、放熱部材37の姿勢を制御することが好ましい。つまり、温度検知機構29により検知された定着ベルト30の表面温度Tが所定の温度(例えば、180〜200度)以上になった場合に放熱部材37を接触姿勢に切り替えて高熱伝導部材34に蓄えられた熱を放出させ、定着ベルト30の表面温度Tが所定の温度(例えば、160〜180度)以下になった場合には、放熱部材37を離間姿勢に切り替えて、定着ベルト30の温度が必要以上に低下することを防止できる。   Conversely, a configuration may be adopted in which the heat radiating member 37 is arranged in a contact posture during the fixing operation. In this case, in order to prevent the fixing belt 30 from falling below the target temperature T1 as described above, it is preferable to control the position of the heat radiation member 37 based on the surface temperature T of the fixing belt 30. That is, when the surface temperature T of the fixing belt 30 detected by the temperature detection mechanism 29 becomes equal to or higher than a predetermined temperature (for example, 180 to 200 degrees), the heat radiation member 37 is switched to the contact posture and stored in the high heat conduction member 34. When the surface temperature T of the fixing belt 30 becomes equal to or lower than a predetermined temperature (for example, 160 to 180 degrees), the heat radiating member 37 is switched to the separated position, and the temperature of the fixing belt 30 is reduced. Unnecessary lowering can be prevented.

また、小サイズの用紙Pが既定の枚数以上連続で画像形成された場合に、放熱部材37を接触姿勢に切り替え、高熱伝導部材34の熱を放熱部材37の側へ伝達させる制御とすることもできる。   Further, in the case where a predetermined number of small-sized papers P are continuously formed, the heat radiation member 37 is switched to the contact posture, and the heat of the high heat conduction member 34 is transmitted to the heat radiation member 37 side. it can.

ここで、定着装置の構成として、定着ベルト30と加圧ローラ31が圧接した状態と両者の圧接状態から脱圧した脱圧状態とを切り替え可能に設ける構成のものが存在する。そして、この様な構成の定着装置に本実施形態の放熱部材を適用する場合、定着ベルト30と加圧ローラ31の圧接状態と脱圧状態を切り替える圧接機構の駆動源として、上記のモータ38を利用することができる。つまり、図13に示すように、モータ38(図11参照)を、定着ベルト30と加圧ローラ31の圧接および脱圧状態の切り替え(図13に示す加圧ローラ31の矢印D方向の移動動作)と、放熱部材37の姿勢切り替え(放熱部材37の矢印E方向の移動動作)に併用することができる。   Here, as a configuration of the fixing device, there is a configuration in which a state in which the fixing belt 30 and the pressure roller 31 are pressed against each other and a depressurized state in which the pressure is released from the pressed state of both are switchably provided. When the heat radiating member of the present embodiment is applied to the fixing device having such a configuration, the motor 38 is used as a driving source of a pressing mechanism for switching between a pressed state and a released state of the fixing belt 30 and the pressing roller 31. Can be used. That is, as shown in FIG. 13, the motor 38 (see FIG. 11) is switched between the pressure contact state of the fixing belt 30 and the pressure roller 31 and the depressurized state (moving operation of the pressure roller 31 shown in FIG. ) And the switching of the position of the heat radiating member 37 (movement operation of the heat radiating member 37 in the direction of the arrow E).

上記の構成により、定着装置の部材数を減らすことができるだけでなく、定着動作を終了した際に、自動的に放熱部材37を接触姿勢に切り替える構成とすることができる。つまり、定着動作時のみ定着ベルト30と加圧ローラ31が圧接状態になる構成の場合、定着動作の終了により、定着ベルト30と加圧ローラ31が圧接状態から脱圧状態に切り替えられ、これに伴って、放熱部材37を接触姿勢に切り替えることができる。これにより、定着動作時以外は放熱部材37を高熱伝導部材34に接触させ、定着動作が開始される際には、高熱伝導部材34に余分な熱ができる限り蓄えられていない状態にすることができる。   With the configuration described above, not only the number of members of the fixing device can be reduced, but also the heat radiation member 37 can be automatically switched to the contact posture when the fixing operation is completed. That is, in a configuration in which the fixing belt 30 and the pressure roller 31 are in a pressure-contact state only during the fixing operation, the fixing belt 30 and the pressure roller 31 are switched from the pressure-contact state to the depressurized state by the end of the fixing operation. Accordingly, the heat radiating member 37 can be switched to the contact posture. Thus, the heat radiating member 37 is brought into contact with the high thermal conductive member 34 except during the fixing operation, and when the fixing operation is started, it is possible to make the state in which excess heat is not stored in the high thermal conductive member 34 as much as possible. it can.

さらに、上記の脱圧状態では、加圧ローラ31からの加圧が解除されることにより、定着ベルト30の外周形状が、自らの弾性力によって図2の形状から円形状に戻る。これにより、図13に示すように、定着ベルト30と高熱伝導部材34の間に隙間Eが生じている。この隙間Eが生じた状態で放熱部材37を離間姿勢から接触姿勢に切り替えることにより、姿勢切り替え時に、放熱部材37が定着ベルト30の内周面30aに接触せず、定着ベルト30の内周面30aを傷つけることを防止できる。   Further, in the above-described depressurized state, when the pressure from the pressure roller 31 is released, the outer peripheral shape of the fixing belt 30 returns to the circular shape from the shape of FIG. 2 by its own elastic force. Thereby, as shown in FIG. 13, a gap E is generated between the fixing belt 30 and the high heat conductive member 34. By switching the heat radiation member 37 from the separated posture to the contact posture in a state where the gap E is generated, the heat radiation member 37 does not contact the inner peripheral surface 30a of the fixing belt 30 when the posture is switched, and the inner peripheral surface of the fixing belt 30 is not changed. 30a can be prevented from being damaged.

放熱部材37は、高熱伝導部材34の特に幅方向端面34aにのみ接触することが好ましい。つまり、上記の様に定着ベルト30と加圧ローラ31が脱圧状態になり、定着ベルト30と高熱伝導部材34の間に隙間Eを生じる構成では、図14に示すように、放熱部材37を高熱伝導部材34の側面に引っ掛ける構成とし、放熱部材37を高熱伝導部材34に確実に接触させ、その接触面積を大きくすることもできる。しかし、定着ベルト30と加圧ローラ31が十分に脱圧されず、隙間Eが微小な定着装置では、放熱部材37の定着ベルト30の内周面30aへの接触の原因となってしまう。放熱部材37が高熱伝導部材34の幅方向端面34aにのみ接触することで、このような不具合を防止できる。   It is preferable that the heat radiating member 37 is in contact with only the width direction end face 34 a of the high heat conductive member 34. That is, in the configuration in which the fixing belt 30 and the pressure roller 31 are released from the pressure as described above and the gap E is generated between the fixing belt 30 and the high heat conduction member 34, as shown in FIG. The heat radiating member 37 can be reliably brought into contact with the high heat conductive member 34 so that the contact area can be increased. However, the pressure of the fixing belt 30 and the pressure roller 31 is not sufficiently released, and in a fixing device having a small gap E, the heat radiation member 37 may contact the inner peripheral surface 30a of the fixing belt 30. Since the heat radiating member 37 contacts only the width direction end surface 34a of the high thermal conductive member 34, such a problem can be prevented.

なお、以上の実施形態の説明では、放熱部材37が高熱伝導部材34およびニップ形成部材33に接触する構成としたが、高熱伝導部材34の熱を効率良く放熱部材37へ伝達し、高熱伝導部材34の高温状態を緩和するためには、放熱部材37を高熱伝導部材34にのみ接触させることが好ましい。このため、図15(a)に示すように、高熱伝導部材34の幅方向端部を定着ベルト30よりも外側に突出させたり、逆に、ニップ形成部材33の幅を小さく設けたり、あるいは、図15(b)に示すように、放熱部材37を高熱伝導部材34にのみ接触する厚みで設けたりすることで、放熱部材37を高熱伝導部材34にのみ接触させることができる。   In the above description of the embodiment, the heat radiating member 37 is configured to be in contact with the high heat conductive member 34 and the nip forming member 33. However, the heat of the high heat conductive member 34 is efficiently transmitted to the heat radiating member 37, In order to alleviate the high temperature state of the heat radiating member 34, it is preferable that the heat radiating member 37 be brought into contact only with the high heat conducting member 34. For this reason, as shown in FIG. 15A, the widthwise end of the high heat conductive member 34 protrudes outside the fixing belt 30, and conversely, the width of the nip forming member 33 is reduced, or As shown in FIG. 15B, the heat radiation member 37 can be brought into contact only with the high heat conduction member 34 by providing the heat radiation member 37 with a thickness that makes contact only with the high heat conduction member 34.

特に図15(a)のように、高熱伝導部材34の幅方向端部を、定着ベルト30から突出させて設けた構成の場合、放熱部材37の移動範囲を定着ベルト30よりも外側に設けることができるので、放熱部材37の姿勢切り替え時に、放熱部材37を定着ベルト30に対して確実に非接触とすることができる。このため、前述の定着ベルト30と加圧ローラ31の脱圧機構を設けていない構成や定着ベルト30と加圧ローラ31が完全に脱圧されない構成の定着装置であっても、定着ベルト30の内周面30aに接触して傷をつけることがない。   In particular, as shown in FIG. 15A, in the case where the widthwise end of the high heat conductive member 34 is provided so as to protrude from the fixing belt 30, the moving range of the heat radiation member 37 is provided outside the fixing belt 30. Therefore, when the posture of the heat radiating member 37 is switched, the heat radiating member 37 can be reliably brought into non-contact with the fixing belt 30. For this reason, even in a fixing device having a configuration in which the pressure release mechanism for the fixing belt 30 and the pressure roller 31 is not provided or a configuration in which the pressure of the fixing belt 30 and the pressure roller 31 are not completely released, the fixing belt 30 No damage is caused by contact with the inner peripheral surface 30a.

本実施形態の変形例として、図16に示すように、放熱部材37の高熱伝導部材34に対する接触面に板バネ(弾性部材)41を設けることもできる。この場合、放熱部材37は、接触姿勢において、板バネ41を介して高熱伝導部材34に接触する。   As a modification of the present embodiment, as shown in FIG. 16, a leaf spring (elastic member) 41 can be provided on a contact surface of the heat radiation member 37 with the high heat conduction member 34. In this case, the heat dissipating member 37 contacts the high heat conducting member 34 via the leaf spring 41 in the contact posture.

高熱伝導部材34は、定着ベルト30からの熱が伝達されることによって幅方向に膨張し、その幅方向の長さが変化する場合がある。この場合でも、上記の構成により、板バネ41が高熱伝導部材34の幅方向の膨張分だけ圧縮変形し、放熱部材37から高熱伝導部材34に対して余計な圧力を加えることがない。   The high heat conductive member 34 expands in the width direction due to the transfer of heat from the fixing belt 30, and the length in the width direction may change. Also in this case, with the above-described configuration, the leaf spring 41 is compressed and deformed by an amount corresponding to the expansion in the width direction of the high heat conductive member 34, so that unnecessary pressure is not applied from the heat radiating member 37 to the high heat conductive member 34.

以上、本発明の実施形態について説明したが、本発明は上述の実施形態に限定されるものではなく、本発明の要旨を逸脱しない範囲で種々の変更を加え得ることは勿論である。   Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

以上の実施形態では、定着ベルト30と加圧ローラ31が脱圧状態に切り替わる際に、放熱部材37が離間姿勢から接触姿勢に切り替わる構成を説明したが、これとは逆に、定着ベルト30と加圧ローラ31が圧接状態に切り替わる際に、放熱部材37が離間姿勢から接触姿勢に切り替わる構成とすることも可能である。   In the above embodiment, when the fixing belt 30 and the pressure roller 31 are switched to the depressurized state, the configuration in which the heat radiating member 37 switches from the separated posture to the contact posture is described. When the pressure roller 31 is switched to the pressure contact state, the heat radiation member 37 may be configured to switch from the separated posture to the contact posture.

本発明に係る画像形成装置は、図1に示すカラー画像形成装置に限らず、モノクロ画像形成装置や、複写機、プリンタ、ファクシミリ、あるいはこれらの複合機等であってもよい。   The image forming apparatus according to the present invention is not limited to the color image forming apparatus shown in FIG. 1, but may be a monochrome image forming apparatus, a copying machine, a printer, a facsimile, or a multifunction peripheral thereof.

記録媒体としては、用紙P(普通紙)の他、厚紙、はがき、封筒、薄紙、塗工紙(コート紙やアート紙等)、トレーシングペーパ、OHPシート等が含まれる。   The recording medium includes, in addition to paper P (plain paper), thick paper, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, and the like.

1 画像形成装置
7 定着装置
29 温度検知機構
30 定着ベルト(定着部材)
30a 内周面
31 加圧ローラ(加圧部材)
32 ハロゲンヒータ(加熱源)
33 ニップ形成部材
34 高熱伝導部材
34a 幅方向端面
37 放熱部材
41 板バネ(弾性部材)
N 定着ニップ
DESCRIPTION OF SYMBOLS 1 Image forming apparatus 7 Fixing device 29 Temperature detection mechanism 30 Fixing belt (fixing member)
30a inner peripheral surface 31 pressure roller (pressure member)
32 Halogen heater (heating source)
33 Nip forming member 34 High heat conductive member 34a End face in width direction 37 Heat radiating member 41 Leaf spring (elastic member)
N fixing nip

特開2015−64560号公報JP-A-2015-64560 特開2015−102718号公報JP 2015-102718 A 特開2015−194661号公報JP-A-2015-194661

Claims (10)

回転可能な定着部材と、
前記定着部材を加熱する加熱源と、
前記定着部材に当接し、定着ニップを形成する加圧部材と、
前記定着部材の内側に設けられたニップ形成部材と、
前記ニップ形成部材と前記定着部材の間に配置され、前記ニップ形成部材よりも熱伝導率の高い部材によって形成される高熱伝導部材とを備えた定着装置において、
前記高熱伝導部材に接触する接触姿勢と、前記高熱伝導部材から離間する離間姿勢とを切り替え可能に設けられる放熱部材を有することを特徴とする定着装置。
A rotatable fixing member,
A heating source for heating the fixing member,
A pressure member that contacts the fixing member and forms a fixing nip;
A nip forming member provided inside the fixing member,
A fixing device, comprising: a high heat conductive member disposed between the nip forming member and the fixing member, the member having higher thermal conductivity than the nip forming member;
A fixing device comprising a heat radiating member provided so as to be able to switch between a contact posture in contact with the high heat conduction member and a separation posture away from the high heat conduction member.
前記放熱部材は、前記高熱伝導部材と同等以上の熱伝導率を有する部材によって形成される請求項1記載の定着装置。   The fixing device according to claim 1, wherein the heat radiating member is formed of a member having a thermal conductivity equal to or higher than the high thermal conductive member. 前記放熱部材は、前記接触姿勢において、前記高熱伝導部材の幅方向端部に接触する請求項1または2いずれか記載の定着装置。   The fixing device according to claim 1, wherein the heat dissipating member contacts the widthwise end of the high heat conductive member in the contact posture. 前記放熱部材は、前記接触姿勢において、前記高熱伝導部材の幅方向端面に接触する請求項3記載の定着装置。   The fixing device according to claim 3, wherein the heat radiating member contacts the widthwise end surface of the high heat conductive member in the contact posture. 前記放熱部材は複数のフィンを有する放熱フィンである請求項1から4いずれか1項に記載の定着装置。   The fixing device according to claim 1, wherein the heat radiation member is a heat radiation fin having a plurality of fins. 前記放熱部材は、前記定着装置の記録媒体に対する画像の定着動作時以外に、前記接触姿勢に配置される請求項1から5いずれか1項に記載の定着装置。   The fixing device according to claim 1, wherein the heat radiating member is disposed in the contact posture other than during a fixing operation of an image on a recording medium of the fixing device. 前記定着部材の温度を検知する温度検知機構を有し、
前記温度検知機構により検知された前記定着部材の温度に基づいて、前記放熱部材の前記接触姿勢と前記離間姿勢の切り替えを行う請求項1から6いずれか1項に記載の定着装置。
A temperature detecting mechanism for detecting a temperature of the fixing member,
The fixing device according to claim 1, wherein switching between the contact posture and the separation posture of the heat radiation member is performed based on a temperature of the fixing member detected by the temperature detection mechanism.
前記定着部材と前記加圧部材が圧接して前記定着ニップを形成する圧接状態と、前記定着部材と前記加圧部材の圧接状態から脱圧した脱圧状態とを切り替え可能な圧接機構を有し、
前記圧接機構は、前記脱圧状態と前記圧接状態との切り替えに伴って、前記放熱部材の前記接触姿勢と前記離間姿勢との切り替えを行う請求項1から7いずれか1項に記載の定着装置。
A pressure-contact mechanism that can switch between a pressure-contact state in which the fixing member and the pressure member are pressed against each other to form the fixing nip, and a depressurized state in which the pressure is released from the pressure-contact state of the fixing member and the pressure member; ,
8. The fixing device according to claim 1, wherein the pressing mechanism switches between the contact posture and the separation posture of the heat radiation member in accordance with switching between the depressurized state and the pressed state. 9. .
前記放熱部材は弾性部材を有し、前記弾性部材を介して前記高熱伝導部材に接触する請求項1から8いずれか1項に記載の定着装置。   9. The fixing device according to claim 1, wherein the heat radiating member has an elastic member, and contacts the high heat conductive member via the elastic member. 10. 請求項1から9いずれか1項に記載の定着装置を備えた画像形成装置。   An image forming apparatus comprising the fixing device according to claim 1.
JP2016075820A 2016-04-05 2016-04-05 Fixing device, image forming device Expired - Fee Related JP6638530B2 (en)

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