JP2004235023A - Heating device, image forming device equipped with the same, and heating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating device with a small load imposed on a heating roller capable of reducing power consumption, and to provide an image forming device equipped with the same and a heating method. <P>SOLUTION: The heating device comprises a heating roller 231 and a pressure roller 232 pressure-contacting each other, and a recording paper P is heated by passing through a fixing nip Y where both rollers 231, 232 pressure-contact with each other. An outside heating roller 233 heats the pressure roller 232 from outside. A time for the recording paper P to pass through the nip Y is within 2.3×10<SP>-2</SP>second. Surface temperatures T1, T2 satisfy a relation T1-T2≤100(°C) on condition that the surface temperature of the pressure roller 231 is T1(°C), and the surface temperature of the pressure roller 232 is T2(°C). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０１１２】
なお、比較例▲２▼・▲３▼、および、構成▲１▼〜▲３▼では、ニップ通過時間は１９．２ミリ秒（ｍｓｅｃ）（記録紙ＰとしてＡ４サイズのものを用いてヨコ送りとした場合、コピー速度は６５枚／分）とし、定着ニップ部Ｙの幅（図中矢印Ａ方向の長さ）（定着ニップ幅）は７ｍｍとする。また、比較例▲１▼では、ニップ通過時間は１７．８ミリ秒とし、定着ニップ幅は６．５ｍｍとする。
【０１１３】
表１に示すように、加圧ローラ２３２を加熱しない構成の比較例▲１▼・▲２▼では、非常に高い面圧（３６０ｋＰａ以上）が必要となることがわかる。
【０１１４】
これは、加熱ローラ２３１の表面温度Ｔ１は限界温度である２００℃に制御されているにもかかわらず、ニップ通過時間が非常に短いために、トナーの溶融に必要な熱エネルギーが加熱ローラ２３１から記録紙Ｐに伝わらないからである。また、加圧ローラ２３２が熱源（例えば、外部加熱ローラ２３３やヒータランプのような加熱手段）を持っていないため加圧ローラ２３２の表面温度Ｔ２が１００℃以下（即ち、Ｔ１−Ｔ２＞１００（℃（ｄｅｇ）））となり、加圧ローラ２３２から記録紙Ｐに伝達される熱エネルギーが少ないため、これを補うために非常に高い定着荷重が必要となるからである。
【０１１５】
一方、比較例▲３▼および構成▲１▼〜▲３▼のように、加圧ローラ２３３を加熱する加熱手段（外部加熱ローラ２３３やヒータランプ）を設けることで、加圧ローラ２３２の表面温度Ｔ２を高温状態（即ち、Ｔ１−Ｔ２≦１００（℃（ｄｅｇ）））に維持すれば、加圧ローラ２３２から記録紙Ｐに伝達される熱エネルギーが増えるため、必要定着荷重を３００ｋＰａ以下に低減することができる。
【０１１６】
ここで、図２は、表１に示す必要面圧（ｋＰａ）と、加熱ローラ２３１の表面温度Ｔ１と加圧ローラ２３２の表面温度Ｔ２との差（Ｔ１−Ｔ２（℃））との関係を示すグラフである。
【０１１７】
同図に示すように、比較例▲１▼〜▲３▼および構成▲１▼〜▲３▼に基づき、必要面圧Ｐ（ｋＰａ）と加熱ローラ２３１・加圧ローラ２３２間の温度差Ｔ１−Ｔ２（℃）との関係を最小２乗法で近似すると、Ｔ１−Ｔ２＝３０×ｌｎ（Ｐ）−７２．５と近似することができる。
【０１１８】
また、上述したように、加熱ローラ２３１・加圧ローラ２３２間の温度差Ｔ１−Ｔ２（℃）は小さい方が、加圧ローラ２３２から記録紙Ｐに伝達される熱エネルギーが増えるため、必要定着荷重を低減することができることを考えると、必要面圧Ｐ（ｋＰａ）と加熱ローラ２３１・加圧ローラ２３２間の温度差Ｔ１−Ｔ２（℃）との関係は、次式（１）で表されることが好ましい。
【０１１９】
Ｔ１−Ｔ２≦３０×ｌｎ（Ｐ）−７２．５ …（１）
このように、外部加熱ローラ２３３により加圧ローラ２３２を加熱維持すれば、十分な定着性を確保できる。
【０１２０】
以上のように、定着装置２３は、互いに圧接する加熱ローラ２３１と加圧ローラ２３２とを備え、加熱ローラ２３１と加圧ローラ２３２とが圧接する定着ニップ部Ｙ（圧接領域）記録紙Ｐが通過することにより記録紙Ｐが加熱される。これにより、記録紙Ｐ上のトナーＴは定着される。
【０１２１】
また、外部加熱ローラ２３３は、加圧ローラ２３２の外側から、加圧ローラ２３２を加熱する。また、記録紙Ｐ上の任意の一点が定着ニップ部Ｙを通過する通過時間は２．３×１０^−２秒以下である。即ち、この定着装置２３は、高速機に適用される。このとき、加熱ローラ２３１の表面温度をＴ１（℃）とし、加圧ローラ２３２の表面温度をＴ２（℃）とすると、表面温度Ｔ１およびＴ２は、Ｔ１−Ｔ２≦１００（℃）を満足する。あるいは、Ｔ１−Ｔ２≦７０（℃）を満足するとさらに好ましい。
【０１２２】
上記の構成によれば、高速機であっても、定着ニップ部Ｙの面圧を大きくしなくてすむ。即ち、ローラ２３１・２３２にかかる荷重を小さくすることができる。
【０１２３】
従って、ローラ、特に加熱ローラ２３１の薄型化を図ることができ、熱容量を低減することができる。これにより、定着装置２３のウォームアップ時間を短縮することがでる。この結果、定着装置２３において予熱する必要がなく、ウォームアップ時および待機時にかかる消費電力の低減を図ることができる。
【０１２４】
また、ローラ２３１・２３２にかかる荷重が小さいことにより、例えば、ローラ２３１・２３２におけるクリープの発生やライフの短縮化を防止できる。
【０１２５】
さらに、ローラ２３１・２３２加の薄型化が可能なことにより、定着装置２３の小型化を図ることができる。また、ローラ２３１・２３２の駆動トルクを小さくすることができるため、消費電力の削減を図ることができると共に、駆動部品のライフの短縮化を防止できる。
【０１２６】
また、加熱ローラ２３１の表面温度と加圧ローラ２３２の表面温度との差は、外部加熱ローラ２３３により制御される。
【０１２７】
具体的には、定着装置２３は、外部加熱ローラ２３３の表面温度を検出する温度センサ２３６と、該検出結果に基づいて、外部加熱ローラ２３３の表面温度を制御する制御手段（図示なし）とを備える。
【０１２８】
これにより、加熱ローラ２３１の表面温度と加圧ローラ２３２の表面温度とのを簡単な構成で制御することができる。
【０１２９】
一方、加熱ローラ２３１の表面温度は略一定に保持されるように制御される。
【０１３０】
これにより、加熱ローラ２３１の表面温度と加圧ローラ２３２の表面温度との差は、外部加熱ローラ２３３によって加圧ローラ２３２の表面温度のみにより制御することができる。
【０１３１】
また、定着装置２３は、定着ニップ部Ｙにおける記録紙Ｐへの面圧をＰ（ｋＰａ）とすると、加熱ローラ２３１の表面温度Ｔ１（℃）と加圧ローラ２３２の表面温度Ｔ２（℃）とは、Ｔ１−Ｔ２≦３０×ｌｎ（Ｐ）−７２．５を満足することが好ましい。
【０１３２】
これにより、Ｔ１−Ｔ２を小さくすることができ、記録紙Ｐに伝達される熱量を増加させることができる。従って、加圧ローラ２３２にかかる荷重を小さくすることができる。
【０１３３】
次に、上述した比較例▲３▼および構成▲１▼〜▲３▼に関して、ウォームアップ時間およびエネルギー消費効率の比較を、表２を用いて行う。なお、構成▲１▼〜▲３▼については、各必要定着荷重に対して、加熱ローラ２３１のたわみ量が許容量以下になるように、加熱ローラ２３１の芯金２３１ａの肉厚を各々設定した。
【０１３４】
【表２】

【０１３５】
また、図３は、表２に示すウォームアップ時間およびエネルギー消費効率と加熱ローラ２３１・加圧ローラ２３２間の温度差Ｔ１−Ｔ２（℃）との間の関係を示すグラフである。
【０１３６】
表２に示すように、比較例▲３▼は、構成▲１▼〜▲３▼とは異なり、加圧ローラ２３２がヒータランプにより内部から加熱される構成であるため、ウォームアップ時間が４２４秒となり、構成▲１▼〜▲３▼と比較して極端に長くなる。
【０１３７】
これは、加圧ローラ２３２の熱容量が大きく、かつ、シリコーンゴムからなる耐熱弾性体層２３２ｂの熱伝導性が悪いために、加圧ローラ２３２表面を所定の温度（ここでは１３０℃）に加熱するのに、非常に時間を要するためである。
【０１３８】
従って、加圧ローラ２３２を加熱する方法としては、ヒータランプ等を用いた内部加熱方式よりも、外部加熱ローラ２３３等により外部から加熱する外部加熱方式の方が好ましいといえる。
【０１３９】
さらに、表２・図３によれば、外部加熱方式を用いたもの（構成▲１▼〜▲３▼）の中でも、エネルギー消費効率（１時間当たりの消費電力量（Ｗｈ／ｈ））の観点からは、構成▲１▼よりも、構成▲２▼・▲３▼のように、Ｔ１−Ｔ２≦７０（℃）となるよう加圧ローラ２３２を加熱した場合の方が、エネルギー消費効率をより低減することができる。
【０１４０】
これは、Ｔ１−Ｔ２≦７０（℃）の場合、ウォームアップ時間（加熱ローラが定着温度（予め設定された所定の温度）に到達するまでの時間）を３０秒以下とすることができることから、低電力モードへの移行時間（スタンバイモード）の１５分以下でオフモード設定が可能となるためである。なお、ここでは、スタンバイモードの時間を６分と設定している。
【０１４１】
ここで、図４は、表２により、構成▲１▼〜▲３▼について、加熱ローラ２３１における軸方向の単位長さ（ｍ）当りの熱容量（Ｊ／ｍ℃）と、ウォームアップ時間（秒）との関係について示すグラフである。
【０１４２】
同図によれば、ウォームアップ時間を３０秒以下とすることができるのは、加熱ローラ２３１における軸方向の単位長さ当りの熱容量を２００（Ｊ／ｍ℃）以下とすればよいことがわかる。
【０１４３】
ところで、上述したように、加圧ローラ２３２の表面温度Ｔ２を高温状態（即ち、Ｔ１−Ｔ２≦１００（℃）、あるいは、さらにＴ１−Ｔ２≦７０（℃））としたとしても、例えば、加圧ローラ２３２を構成する材料の熱伝導率が極端に低い場合等は、加圧ローラ２３２から記録紙Ｐに十分な熱量が伝わらず、トナーＴが定着不良となる場合がある。
【０１４４】
そこで、以下、加熱ローラ２３１および加圧ローラ２３２から記録紙Ｐに伝わる熱エネルギーと、必要定着荷重（Ｎ）（必要面圧（ｋＰａ））との関係について検討する。
【０１４５】
ここで、上述した、比較例▲１▼〜▲３▼および構成▲１▼〜▲３▼について、加熱ローラ２３１から記録紙Ｐ（１枚当り）に伝わる熱エネルギーＱ１、加圧ローラ２３２から記録紙（１枚当り）Ｐに伝わる熱エネルギーＱ２を２次元伝熱シミュレーションにより求める。なお、熱エネルギーＱ１・Ｑ２、これら熱エネルギーＱ１・Ｑ２の比、必要定着荷重（Ｎ）、必要面圧（ｋＰａ）、ウォームアップ時間、および、エネルギー消費効率を表３に示す。
【０１４６】
【表３】

【０１４７】
表３に示すように、記録紙Ｐに伝わる総熱量（総熱エネルギー）（Ｑ１＋Ｑ２）に対する加圧ローラ２３２から記録紙Ｐに伝わる熱エネルギーＱ２の割合（Ｑ２／（Ｑ１＋Ｑ２））としては、加熱手段のない比較例▲１▼・▲２▼では２２％程度しかない。このため、非常に高い定着荷重（面圧３５０ｋＰａ以上）が必要であった。
【０１４８】
一方、比較例▲３▼および構成例▲１▼〜▲３▼では、加圧ローラ２３２を加熱する加熱手段が設けられているため、加圧ローラ２３２から記録紙Ｐへ伝達される熱エネルギーＱ２の割合が２５％以上となる。これにより、必要面圧が３００ｋＰａ以下となり、必要定着荷重を低減することができる。
【０１４９】
ここで、図５は、表３に示す必要面圧Ｐ（ｋＰａ）と、加圧ローラ２３２から記録紙Ｐに伝わる熱量Ｑ２の、総熱量Ｑ１＋Ｑ２に対する割合Ｑ２／Ｑ１＋Ｑ２との関係を示すグラフである。
【０１５０】
同図に示すように、比較例▲１▼〜▲３▼および構成▲１▼〜▲３▼に基づき、必要面圧Ｐ（ｋＰａ）と総熱量Ｑ１＋Ｑ２に対する熱量Ｑ２の割合Ｑ２／Ｑ１＋Ｑ２との関係を最小２乗法で近似すると、Ｑ２／Ｑ１＋Ｑ２＝−０．０７８×ｌｎ（Ｐ）＋０．７と近似することができる。
【０１５１】
また、上述したように、Ｑ２／（Ｑ１＋Ｑ２）は大きい方が、加圧ローラ２３２から記録紙Ｐに伝達される熱エネルギーが増えるため必要定着荷重を低減できることを考えると、必要面圧Ｐ（ｋＰａ）と総熱量Ｑ１＋Ｑ２に対する熱量Ｑ２の割合Ｑ２／Ｑ１＋Ｑ２との関係は、次式（２）で表されることが好ましい。
【０１５２】
Ｑ２／Ｑ１＋Ｑ２≧−０．０７８×ｌｎ（Ｐ）＋０．７ …（２）
このように、外部加熱ローラ２３３により加圧ローラ２３２を加熱維持すれば、Ｑ２／Ｑ１＋Ｑ２、即ち、加圧ローラ２３２から記録紙Ｐに伝達される熱量Ｑ２の割合を大きくすることができ、必要定着荷重を低減することができる。従って、消費電力の低減を図ることができると共に、記録紙Ｐ上のトナーＴにおいて、十分な定着性を確保することができる。
【０１５３】
次に、表３に示す構成▲１▼〜▲３▼に関して、ウォームアップ時間およびエネルギー消費効率の比較を図６を用いて行う。
【０１５４】
図６は、表３に示すウォームアップ時間およびエネルギー消費効率と、総熱量Ｑ１＋Ｑ２に対する熱量Ｑ２の割合Ｑ２／Ｑ１＋Ｑ２との間の関係を示すグラフである。
【０１５５】
表３・図６に示すように、構成▲２▼・▲３▼は、Ｑ２／Ｑ１＋Ｑ２≧０．３１３となり、構成▲１▼と比較して、エネルギー消費効率をより低減することができる。
【０１５６】
これは、Ｑ２／（Ｑ１＋Ｑ２）≧０．３１３（０．３）の場合、ウォームアップ時間が３０秒以下となることから、低電力モードへの移行時間（スタンバイモード）の１５分以下でオフモード設定が可能となるためである。なお、ここでは、スタンバイモードの時間を６分と設定している。
【０１５７】
なお、ローラ２３１・２３２・２３３の形状および材料は、上述したものに特に限定されるものではない。
【０１５８】
また、ローラ２３１・２３２・２３３を備えた構成の装置の一例として定着装置（加熱装置）２３として説明したが、これに限定されるものではなく、例えば、湿式電子写真方式の画像形成装置における乾燥装置、インクジェットプリンタにおける乾燥装置、あるいは、リライタブルメディア用の消去装置等に好適に用いることができる。
【０１５９】
以下、上述した定着装置２３を、乾式電子写真方式の画像形成装置に適用した例について、図８〜図１５を用いてその構成を説明する。
【０１６０】
図８は、画像形成装置を外側から見た構成を示す斜視図であり、図９は、画像形成装置の内部の構成を示す図である。
【０１６１】
図８・図９に示すように、画像形成装置は、原稿画像読取装置１１、画像記録装置１２、記録材供給装置１３、後処理装置１４、外部記録材供給装置１５を備えている。なお、定着装置２３（図１１参照）は、後述するように、画像記録装置１２に備えられている。
【０１６２】
図９に示すように、画像形成部である画像記録装置１２、記録材供給部である記録材供給装置１３、および記録材供給装置１３から画像記録装置１２を経て記録材排出部１６まで記録材（記録紙Ｐ）を搬送する搬送部１７により、デジタルプリンタなどの画像形成装置本体を構成する。画像読取装置である原稿画像読取装置１１をさらに備えることにより、デジタル複写機やファクシミリ装置などを構成することも可能となる。
【０１６３】
画像形成装置本体の動作について、以下に説明する。
【０１６４】
まず、原稿画像読取装置１１が原稿を読み取って画像データを取得し、画像データを画像記録装置１２に出力する。画像記録装置１２は、入力された画像データに適切な画像処理を施す。
【０１６５】
一方、記録材供給装置１３からは、印刷用紙およびＯＨＰ（Ｏｖｅｒ Ｈｅａｄ Ｐｒｏｊｅｃｔｏｒ）シートなどのシート状の記録材が１つずつ分離して搬出され、搬送部１７の第１の搬送経路によって画像記録装置１２に搬送される。
【０１６６】
そして、画像記録装置１２により、印刷などによって画像データに基づく画像が記録材に形成される。画像が印刷された記録材は、搬送部１７の第２の搬送経路によって記録材排出部１６まで搬送されて装置外部に排出される。
【０１６７】
また、原稿画像読取装置１１には、図１０に示すように、原稿供給部もしくは原稿回収部である原稿トレイ１８が取り付けられている。
【０１６８】
この原稿トレイ１８が原稿供給部として働く場合は、複数ページからなる一連の原稿を原稿トレイ１８に載置する。この場合、原稿トレイ１８は、載置された原稿を１枚ずつ分離して連続的に読取部に供給することができる。
【０１６９】
一方、原稿トレイ１８が原稿回収部として働く場合は、連続的に排出される読み取り済み原稿を、原稿トレイ１８で受けて保持する。
【０１７０】
また、例えば読み取った一連の原稿を複数部印刷する場合に、印刷された記録材を図９に示す記録材排出部１６に排出すると、同じページが印刷された記録材が連続して排出されるなど混合されてしまうため、印刷後にユーザが記録材を分別しなければならない。
【０１７１】
そこで、画像形成装置本体に後処理装置１４により、例えば、記録材が混合しないように複数の排出トレイに区別して排出することが可能となっている。また、画像形成装置本体と後処理装置１４とは所定の距離を隔てて設置されており、画像形成装置本体と後処理装置１４との間には空間が形成される。
【０１７２】
なお、画像形成装置本体と後処理装置１４とは外部搬送部１９によって接続されており、画像が印刷された記録材は、搬送部１７から外部搬送部１９を経て後処理装置１４まで搬送される。
【０１７３】
また、省エネルギー化および低コスト化などの観点から、印刷用紙などの記録材では、その両面に画像を印刷する機能が求められている。この機能は、片面に画像が印刷された記録材を、その表裏を反転させて再び画像記録装置１２に搬送する両面印刷用搬送部２１によって実現可能となっている。
【０１７４】
片面に印刷された記録材は、記録材排出部１６にも後処理装置１４にも搬送されず、両面印刷用搬送部２１で表裏が反転されて、再び画像記録装置１２に搬送される。画像記録装置１２は、画像が印刷されていない面に画像を印刷することで両面印刷が可能となる。
【０１７５】
さらに、記録材供給装置１３に保持可能な種類または数量を越える記録材を供給したい場合は、機能拡張用の周辺装置として外部記録材供給装置１５を画像形成装置本体に接続し、所望の種類および数量の記録材を外部記録材供給装置１５に収容することで供給可能となっている。
【０１７６】
次に、画像形成装置を構成する各装置および部位について詳細に説明する。
【０１７７】
図１１は、画像記録装置１２の構成を示す図である。同図に示すように、画像記録装置１２の略中央左側には、感光体ドラム２２を中心とする電子写真プロセス部が配置されている。
【０１７８】
感光体ドラム２２を中心としてその周囲には、感光体ドラム２２表面を均一に帯電させる帯電ユニット３１と、均一に帯電された感光体ドラム２２に光像を走査して静電潜像を書き込む光走査ユニット２４と、光走査ユニット２４によって書き込まれた静電潜像を現像剤により現像する現像ユニット２５と、感光体ドラム２２表面に記録現像された画像を記録材に転写する転写ユニット２６と、感光体ドラム２２表面に残留した現像剤を除去して感光体ドラム２２に新たな画像を記録することを可能とするクリーニングユニット２７等などが順次配置されている。
【０１７９】
電子写真プロセス部（像転写装置）の上方には、定着装置２３が配置されており、転写ユニット２６によって画像が転写された記録材を順次受け入れ、記録材に転写された現像剤（トナー）を加熱定着する。
【０１８０】
画像が印刷された記録材は、印刷面を下に向けた状態（フェイスダウン）で画像記録装置１２上部の記録材排出部１６から排出される。なお、このクリーニングユニット２７により除去された残留現像剤は回収され、現像ユニット２５の現像剤供給部２５ａに戻されて再利用される。
【０１８１】
画像記録装置１２の下部には、記録材を収容する記録材供給部２０が装置内に内装されて配置されている。記録材供給部２０は、記録材を１枚ずつ分離して電子写真プロセス部に供給する。
【０１８２】
搬送部１７は、複数のローラ２８およびガイドからなり、記録材は、記録材供給部２０から、ローラ間、ガイド間および感光体ドラム２２と転写ユニット２６との間などで規定される第１の搬送経路を通り、画像が印刷された後、ローラ間、ガイド間および定着ユニット３１間などで規定される第２の搬送経路を通って記録材排出部１６に排出される。
【０１８３】
なお、この記録材供給部２０に記録材をセットする場合は、画像記録装置１２の搬送方向に直交する方向、即ち、前面側方向に記録材収容トレイを引き出して記録材の補給、あるいは記録材の交換などを行う。
【０１８４】
また、画像記録装置１２の下面には、増設ユニットの記録材供給装置１３（図１２参照）から送られてくる記録材を受け入れ、感光体ドラム２２と転写ユニット２６との間に向かって順次供給するための記録材受け入れ部３２が設けられている。
【０１８５】
さらに、光走査ユニット２４周辺の空隙部には、電子写真プロセス部をコントロールするプロセスコントロールユニット（ＰＣＵ）基板、装置外部からの画像データを受け入れるインターフェイス基板、インターフェイス基板から受け入れられた画像データおよび原稿画像読取装置１１が読み取った画像データに対して所定の画像処理を施し、光走査ユニットにより画像として走査記録させるためのイメージコントロールユニット（ＩＣＵ）基板、そして、これら各種基板、ならびにユニットに対して電力を供給する電源ユニット等が配置されている。
【０１８６】
なお、画像記録装置１２単体でもインターフェイス基板を介してパーソナルコンピュータなどの外部機器と接続し、外部機器からの画像データを記録材に形成するプリンタとして動作させることが可能である。
【０１８７】
上記の説明においては、画像記録装置１２内に内装された記録材供給部２０は１つとして説明しているが、これに限定されるものではなく、例えば、それ以上の記録材供給部を装置内に内装することも可能である。
【０１８８】
図１２は、増設ユニットの記録材供給装置１３の構成を示す断面図である。記録材供給装置１３は、記録材供給部２０だけでは記録材の数量が不足する場合などに画像記録装置１２の一部として増設することができる。
【０１８９】
記録材供給装置１３は、記録材供給部２０に収容される記録材よりも大きなサイズの記録材を収容することも可能であり、収容されている記録材を１枚ずつ分離して、記録材供給装置１３上面に設けられた記録材排出部３３に向かって搬出する。
【０１９０】
記録材供給装置１３において、トレイは、記録材収容トレイ３４ａ〜３４ｃの３段からなり、積層された記録材収容トレイ３４ａ〜３４ｃの中から所望する記録材を収容した記録材収容トレイを、ＰＣＵなどが制御して選択的に動作させ、収容されている記録材を分離搬出する。
【０１９１】
搬出された記録材は、記録材排出部３３から画像記録装置１２の下部に設けられた記録材受け入れ部３２を通って電子写真プロセス部へと至る。なお、記録材供給装置１３に記録材をセットする場合は、記録材供給装置１３の前面側方向に記録材収容トレイ３４ａ〜３４ｃのいずれかを引き出して記録材の補給、あるいは記録材の交換などを行うものである。
【０１９２】
上記の説明では３つの記録材収容トレイ３４ａ〜３４ｃが積層された場合について説明しているが、積層するトレイの数は、例えば、少なくとも１つ、もしくは３つ以上とすることができる。
【０１９３】
なお、記録材供給装置１３面には、複数の車輪３５…が設けられており、増設時などに容易に記録材供給装置１３を含む画像形成装置本体が移動可能となっている。また、ストッパ３６によって設置場所に固定することも可能である。
【０１９４】
図１３は、外部記録材供給装置１５の構成を示す図である。外部記録材供給装置１５は、画像記録装置１２が備える記録材供給装置１３に収容可能な種類および数量を越える記録材を収容することが可能であるとともに、収容されている記録材を１枚ずつ分離して、装置の側面上部に設けられた記録材排出部３７に向かって搬出する。
【０１９５】
記録材排出部３７から搬出された記録材は、画像記録装置１２の側面下部に設けられた外部記録材受け入れ部３８（図１１参照）へと受け渡される。
【０１９６】
外部記録材供給装置１５に記録材をセットする場合は、外部記録材供給装置１５の上部に形成された図８に示す補給口１５１から記録材の補給、あるいは記録材の交換などを行う。また、補給口１５１には開閉可能な蓋１５２が設けられ、補給あるいは交換などの場合以外では、補給口が閉じられている構成にしてもよい。
【０１９７】
なお、外部記録材供給装置１５下面には、図１３に示すように、複数の車輪３９…が設けられており、増設時などに容易に移動可能となっている。また、ストッパによって設置場所に固定することも可能である。
【０１９８】
図１４は、後処理装置１４の構成を示す図である。後処理装置１４は、図９に示すように、画像形成装置本体と所定の距離を隔てて設置される。後処理装置１４と画像形成装置本体とは、外部搬送部１９によって接続されており、画像形成装置本体によって画像が印刷された記録材は、外部搬送部１９を経て後処理装置１４に搬送される。
【０１９９】
なお、外部搬送部１９の一端は、画像記録装置１２の外部排出部２１２と接続し、他端は、後処理装置１４の記録材受け入れ部４１と接続している。
【０２００】
後処理装置１４は、図１４に示すように、搬送された記録材を排出トレイ４２あるいは排出トレイ４３に選択的に排出可能なソート搬送部４４を有している。ソート搬送部４４は、複数のローラ４５…、ガイドおよび搬送方向切換ガイド４６からなり、搬送方向切換ガイド４６を制御することによって排出先のトレイを切り換えることができる。ユーザは、記録材の排出先として排出トレイ４２・４３のいずれかを選択することが可能で、画像が印刷された記録材を区別して排出することができる。
【０２０１】
なお、後処理としては、上述のようなソータ処理以外に、所定枚数の記録材に対してステープル処理を施したり、Ｂ４，Ａ３サイズなどの印刷用紙を紙折りしたり、記録材にファイリング用の穴をあけたりする後処理を施すことも可能である。
【０２０２】
また、後処理装置１４の下面には、車輪４８が設けられており、容易に移動させることが可能である。
【０２０３】
なお、外部搬送部１９の構成としては特に限定されるものではなく、外部搬送部１９が後処理装置１４に備えられ、外部搬送部１９と画像記録装置１２とが着脱可能に構成されていてもよいし、外部搬送部１９と後処理装置１４および画像形成装置本体２０とが、着脱可能に構成されていてもよい。
【０２０４】
図１０は、原稿画像読取装置１１の構成を示す図である。原稿画像読取装置１１は、シート状の原稿を自動原稿供給装置（ＡＤＦ）により自動的に供給して１枚ずつ順次露光走査し、原稿を読み取る自動読み取りモードと、ブック状の原稿、もしくはＡＤＦによる自動供給が不可能なシート状の原稿を手動操作によりセットして原稿を読み取る手動読み取りモードとで動作可能である。
【０２０５】
自動もしくは手動によって読取部である透明な原稿読取台４９上にセットされた原稿の画像は、露光走査して光電変換素子上に結像され、電気的信号に変換されて画像データを取得する。取得した画像データは、画像記録装置１２との接続部を介して出力される。
【０２０６】
また、両面原稿を読み取る場合、原稿搬送経路に沿って原稿を搬送する過程において、原稿の両面から原稿画像を同時に走査して読み取ることが可能である。
【０２０７】
原稿の下面の読み取りについては、原稿台下面を走査する移動走査露光光学系が、原稿搬送経路の所定の位置に停止した状態でＣＣＤまで光像を導き、原稿画像を読み取る構成となっている。また、原稿の上面の読み取りについては、原稿搬送経路の上方に位置し、原稿を露光する光源、光像を光電変換素子まで導く光学レンズ、光像を画像データに変換する光電変換素子などから一体的に構成される密着センサ（ＣＩＳ）が配置されている。
【０２０８】
両面原稿の読み取りが選択されると、原稿供給部１１１にセットされた原稿が順次搬送され、搬送に伴って両面の画像がほぼ同時に読み取られる。
【０２０９】
原稿画像読取装置１１には、原稿トレイ１８が取り付けられている。原稿トレイ１８、読み取り前の原稿を供給する場合、もしくは読み取り済みの原稿を受ける場合に使用する。原稿を供給する場合、原稿トレイ１８に読み取り前の原稿を載置すると、ＡＤＦの取り込み部が原稿を取り込み、原稿読取台４９に搬送する。読み取られた原稿は、原稿排出部によって、装置外に排出される。原稿を受ける場合、原稿供給部１１１に原稿を載置すると、ＡＤＦの取り込み部が原稿を取り込み、原稿読取台４９に搬送する。読み取られた原稿は、原稿排出部によって、原稿トレイ１８に排出される。
【０２１０】
図１５は、両面印刷用搬送装置２１の構成を示す図である。両面印刷用搬送装置２１は、両面印刷用搬送部を有し、図１１に示した画像記録装置１２の側面に取り付けられる。
【０２１１】
両面印刷用搬送部は、複数のローラ２１０…を備え、定着装置２３から排出された記録材を、画像記録装置上部の記録材排出部１６を用いてスイッチバック搬送する。即ち、記録材の表裏を反転し、再度、画像記録装置１２の電子写真プロセス部の感光体ドラム２２と転写装置２６との間に向かって記録材を供給することができる。
【０２１２】
なお、画像形成装置１２において、装置上部の記録材排出部１６に向かって記録材を排出する搬送経路において印刷された記録材をスイッチバック搬送することにより、図１４に示す後処理装置１４や図１５に示す両面印刷用装置２１に記録材を導くことが可能となる。
【０２１３】
〔実施の形態２〕
本発明の他の実施の一形態について図１および図７に基づいて説明すれば、以下の通りである。なお、本実施の形態において、実施の形態１における構成要素と同等の機能を有する構成要素については、同一の符号を付記してその説明を省略する。
【０２１４】
ここで、本実施の形態における定着装置は、加熱手段として図１に示す外部加熱ローラ２３３のかわりに、図７に示すように、誘導加熱コイル（外部加熱部材）２４１を備えている。誘導加熱コイル２４１には、図示しない駆動電源が接続されている。また、図７においては、クリーニングローラは図示していない。
【０２１５】
本実施の形態における加圧ローラ２３２は、芯金２３２ａと、芯金２３２ａの外周表面にはシリコーンゴム等からなる耐熱弾性材層２３２ｂと、更にその外側に発熱層２３２ｄと、そして最外層には離型層２３２ｃとが設けられ、４層構造となっている。
【０２１６】
直径２８ｍｍで、アルミニウム、鉄もしくはステンレス鋼等の金属からなる芯金２３２ａ上には、厚さ６ｍｍの発泡シリコーンゴムからなる耐熱弾性体層２３２ｂが形成されている。
【０２１７】
なお、芯金２３２ａの材料としては、誘導加熱による発熱を防止するため、アルミニウムがより望ましい。
【０２１８】
発熱層２３２ｄは、誘導加熱作用により発熱する発熱体であり、表面温度の立ち上がり時間を短縮するために、その肉厚は、４０μｍ〜５０μｍと薄肉化されている。
【０２１９】
また、発熱層２３２ｄは、誘導加熱（電磁誘導によって加熱電流を発生させる加熱）により加熱されるため、鉄やＳＵＳ４３０ステンレス鋼等、磁性および導電性を有する材料からなるものであればよい。特に比透磁率が高い（例えば、１以上）材料が好ましく、珪素鋼板や電磁鋼板、ニッケル鋼等であってもよい。
【０２２０】
なお、非磁性体であっても、ＳＵＳ３０４ステンレス材など抵抗値の高い（例えば、９．８×１０^−６Ω・ｃｍ以上）材料であれば誘導加熱できるのでこれを使用してもよい。また、非磁性のベース部材（例えば、セラミックスからなる部材等）であっても、比透磁率の高い上記材料が導電性を有するように配置されているような構成であればそれでもよい。ここでは、発熱層２３２ｄに電鋳法により作製した厚さ４０μｍのニッケルを使用している。また、発熱層２３２ｄは、発熱量を増大させるために、発熱層を複数の材料からなる層で構成しても良い。
【０２２１】
また、発熱層２３２ｄ表面（外周面）には、定着ニップ部Ｙで加熱され粘度が低下したトナーＴが加熱ローラ２３１に付着するのを防止するために、ＰＴＦＥ（ポリテトラフルオロエチレン）、ＰＦＡ（テトラフルオロエチレンとペルフルオロアルキルビニルエーテルとの共重合体）等のフッ素樹脂、あるいはシリコーンゴム、フッ素ゴム、フロロシリコンゴム等の弾性体、若しくはこれらが複数積層された離型層２３２ｃが被覆されている。
【０２２２】
そして、加圧ローラ２３２は、図示しないばね等の加圧部材により定着ローラ２３１に２７４Ｎの力で圧接され、これにより、定着ローラ２３１との間に幅が約７ｍｍの定着ニップ部Ｙが形成されるよう構成されている。
【０２２３】
加圧ローラ２３２を加熱する加熱手段としては、図に示すように誘導加熱コイル２４１から構成されており、加圧ローラ２３２の外周を取り囲むように構成されている。このように構成すると曲率が存在するため、誘導加熱コイル２４１の中心側に磁束が集中し、渦電流の発生量が多くなるため、加圧ローラ２３２の表面温度をすばやく立ち上げるのに都合が良い。
【０２２４】
誘導加熱コイル２４１の材料としては、ここでは、耐熱性を考慮してアルミニウム単線（表面絶縁層（例えば、酸化膜）あり）を使用しているが、銅線もしくは銅ベースの複合部材線であっても良いし、リッツ線（エナメル線等を撚り線にしたもの）であってもよい。何れの線材を使用しても、誘導加熱コイル２４１でのジュール損を抑えるためには、誘導加熱コイル２４１の全抵抗値は、０．５Ω以下、望ましくは０．１Ω以下であるほうがよい。また、誘導加熱コイル２４１は、トナーＴを定着させる記録紙Ｐのサイズに応じて複数個配置しても良い。
【０２２５】
励磁回路（図示せず）よりこの誘導加熱コイル２４１に高周波電流を流すことで生じる交番磁界により、加圧ローラ２３２は誘導加熱される。
【０２２６】
また、加圧ローラ２３２の周面には、温度検知手段としてのサーミスタ（温度線センサ）２４９が配設されており、加圧ローラ２３２の表面温度を検出するようになっている。そして、検出された温度データに基づいて、図示しない温度制御手段（制御手段）は、加圧ローラ２３２表面の温度が所定の温度となるよう誘導加熱コイル２４１への通電を制御する。
【０２２７】
ここで、加圧ローラ２３２の加熱手段として誘導加熱コイル２４１（誘導加熱方式）を用いた場合（構成▲４▼）と、実施の形態１において上述した外部加熱ローラ２３３（加熱ローラ方式）を用いた場合（構成▲２▼）とについて、通紙時（２０枚）における加熱効率（＝加圧ローラ２３２に伝わった熱量／電源への投入電力）および平均消費電力を比較した結果を表４に示す。
【０２２８】
【表４】

【０２２９】
表４に示すように、加熱ローラ方式では、温度差を利用した加熱ローラ２３１から加圧ローラ２３３への熱伝導により熱供給を行うのに対し、誘導加熱方式では、直接加圧ローラ２３２自体を発熱させるため、加熱ローラ方式に比べ、誘導加熱方式は、加熱効率に優れている。
【０２３０】
また、誘導加熱方式では、誘導加熱コイル２４１自体はほとんど発熱せず、加熱ローラ方式のような雰囲気中への放熱ロスがほとんど無いため、通紙中の平均消費電力が加熱ローラ方式の３７％と、消費電力化の低減を図ることができる。
【０２３１】
本発明は上述した各実施の形態に限定されるものではなく、請求項に示した範囲で種々の変更が可能であり、異なる実施の形態にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施の形態についても本発明の技術的範囲に含まれる。
【０２３２】
【発明の効果】
本発明の加熱装置は、以上のように、第２加熱部材を、該第２加熱部材の外側から加熱する外部加熱部材を備え、被加熱材上の任意の一点が圧接領域を通過する通過時間は２．３×１０^−２秒以下であり、第１加熱部材の表面温度をＴ１（℃）とし、第２加熱部材の表面温度をＴ２（℃）とすると、表面温度Ｔ１およびＴ２は、Ｔ１−Ｔ２≦１００（℃）を満足する構成である。
【０２３３】
あるいは、本発明の加熱装置は、第１加熱部材の表面温度Ｔ１および第２加熱部材の表面温度Ｔ２が、Ｔ１−Ｔ２≦７０（℃）を満足する構成である。
【０２３４】
これにより、被加熱材上の任意の一点が圧接領域を通過する通過時間が２．３×１０^−２秒以下の高速機であっても、圧接領域の面圧を大きくしなくてすむ。即ち、加熱部材にかかる荷重を小さくすることができる。
【０２３５】
従って、加熱部材の薄型化を図ることができ、熱容量を低減することができる。これにより、加熱装置のウォームアップ時間を短縮することがでる。この結果、加熱部材を予熱する必要がなく、ウォームアップ時および待機時にかかる消費電力の低減を図ることができる。
【０２３６】
また、加熱部材にかかる荷重が小さいことにより、例えば、加熱部材におけるクリープの発生やライフの短縮化を防止できる。
【０２３７】
さらに、加熱部材の薄型化が可能なことにより、加熱装置の小型化を図ることができる。また、加熱部材の駆動トルクを小さくすることができるため、消費電力の削減を図ることができると共に、駆動部品のライフの短縮化を防止できるといった効果を奏する。
【０２３８】
本発明の加熱装置は、第１加熱部材の表面温度と第２加熱部材の表面温度との差が、外部加熱部材により制御される構成である。
【０２３９】
具体的には、本発明の加熱装置は、外部加熱部材の表面温度を検出する温度検出手段と、該温度検出手段の検出結果に基づいて、外部加熱部材の表面温度を制御する制御手段とを備える構成である。
【０２４０】
これにより、外部加熱部材が第２加熱部材の外側から第２加熱部材を加熱するため、第２加熱部材の表面温度を簡単に制御することができる。
【０２４１】
従って、第１加熱部材の表面温度と第２加熱部材の表面温度との差を簡単な構成で制御することができるといった効果を奏する。
【０２４２】
本発明の加熱装置は、第１加熱部材の表面温度は略一定に保持されるように制御される構成である。
【０２４３】
これにより、第１加熱部材の表面温度は略一定に保持されるため、第１加熱部材の表面温度と第２加熱部材の表面温度との差は、外部加熱部材によって第２加熱部材の表面温度のみにより制御することができるといった効果を奏する。
【０２４４】
本発明の加熱装置は、圧接領域における上記被加熱材への面圧をＰ（ｋＰａ）とすると、第１加熱部材の表面温度Ｔ１（℃）と第２加熱部材の表面温度Ｔ２（℃）とは、Ｔ１−Ｔ２≦３０×ｌｎ（Ｐ）−７２．５を満足する構成である。
【０２４５】
これにより、Ｔ１−Ｔ２を小さくすることができ、被加熱材に伝達される熱量を増加させることができる。従って、加熱部材にかかる荷重を小さくすることができるといった効果を奏する。
【０２４６】
本発明の加熱装置は、以上のように、被加熱材上の任意の一点が圧接領域を通過する通過時間は２．３×１０^−２秒以下であり、被加熱材の通過時に、第１加熱部材から被加熱材に伝達される熱量をＱ１とし、第２加熱部材から被加熱材に伝達される熱量をＱ２とすると、熱量Ｑ１およびＱ２は、Ｑ２／（Ｑ１＋Ｑ２）≧０．２５を満足する構成である。
【０２４７】
あるいは、本発明の加熱装置は、熱量Ｑ１およびＱ２が、Ｑ２／（Ｑ１＋Ｑ２）≧０．３を満足する構成である。
【０２４８】
これにより、加熱部材がどのような材料からなるものであっても、上述した第１加熱部材の表面温度Ｔ１および第２加熱部材の表面温度Ｔ２がＴ１−Ｔ２≦７０（℃）を満足するように規定した場合と同様の効果を得ることができる。
【０２４９】
即ち、加熱部材にかかる荷重を小さくすることができ、消費電力の低減を図ることができるといった効果を奏する。
【０２５０】
本発明の加熱装置は、第２加熱部材を、該第２加熱部材の外側から加熱する外部加熱部材と、外部加熱部材の表面温度を制御することにより、第２加熱部材から被加熱材に伝達される熱量Ｑ２と、被加熱材に伝達される総熱量Ｑ１＋Ｑ２との比Ｑ２／（Ｑ１＋Ｑ２）を制御する制御手段とを備える構成である。
【０２５１】
これにより、外部加熱部材によりＱ２／（Ｑ１＋Ｑ２）を制御することができる。従って、簡単な構成で、Ｑ２／（Ｑ１＋Ｑ２）の制御を可能とすることができるといった効果を奏する。
【０２５２】
本発明の加熱装置は、圧接領域における被加熱材への面圧をＰ（ｋＰａ）とすると、第２加熱部材から被加熱材に伝達される熱量Ｑ２（Ｊ）と、被加熱材に伝達される総熱量Ｑ１＋Ｑ２（Ｊ）との比Ｑ２／（Ｑ１＋Ｑ２）は、Ｑ２／（Ｑ１＋Ｑ２）≧−０．０７８×ｌｎ（Ｐ）＋０．７を満足する構成である。
【０２５３】
これにより、第２加熱部材から被加熱材に伝達される熱量Ｑ２の割合を大きくすることができ、必要定着荷重を低減することができる。従って、消費電力の低減を図ることができるといった効果を奏する。
【０２５４】
本発明の加熱装置は、圧接領域における被加熱材への面圧が、３００（ｋＰａ）以下である構成である。
【０２５５】
これにより、加熱部材および被加熱材にかかる荷重を小さくすることができるといった効果を奏する。
【０２５６】
本発明の加熱装置は、外部加熱部材が、熱源体を有し、第２加熱部材の表面に接することで第２加熱部材を加熱する構成である。
【０２５７】
これにより、第２加熱部材の表面を直接加熱することができるため、外部加熱部材の構成を簡単にすることができ、また、省スペース化が可能となる。従って、例えば、クリーニングローラ等、他の部品の設置を容易にすることができるといった効果を奏する。
【０２５８】
本発明の加熱装置は、外部加熱部材が、第２加熱部材に外接して該第２加熱部材と共に回転するローラである構成である。
【０２５９】
これにより、簡単な構成で、第２加熱部材を加熱することができる。従って、省スペース化を図ることができ、例えばクリーニング部材等、他の部品の設置が容易となるといった効果を奏する。
【０２６０】
本発明の加熱装置は、第２加熱部材が、誘導加熱作用により発熱する発熱体を備え、外部加熱部材は、第２加熱部材を誘導加熱する誘導加熱コイルである構成である。
【０２６１】
これにより、第２加熱部材を直接発熱させることができることにより、第２加熱部材表面からの放射、対流による熱損失が少ない。また、外部加熱部材自体はほとんど発熱しないため、外部加熱部材自体の熱損失は少ない。従って、さらに熱効率の向上を図ることができるといった効果を奏する。
【０２６２】
本発明の加熱装置は、外部加熱部材の形状が曲率を有する構成である。
【０２６３】
これにより、外部加熱部材としての誘導加熱コイルの中心側に磁束が集中し、渦電流の発生量が多くなる。従って、第２加熱部材の発熱の立ち上がりをはやくすることができるといった効果を奏する。
【０２６４】
本発明の加熱装置は、第１加熱部材の表面が、単位長さ当りの熱容量が２００Ｊ／（ｍ・℃）以下である構成である。
【０２６５】
これにより、例えば、ウォームアップ時間を３０秒以下にすることができ、待機時における消費電力を大幅に削減することができるといった効果を奏する。
【０２６６】
本発明の加熱装置は、第１加熱部材および第２加熱部材が回動可能なローラであり、圧接領域を被加熱材が通過することにより、被加熱材上のトナーを定着させる構成である。
【０２６７】
これにより、加熱装置を定着装置として用いることができる。従って、トナーの定着性を確保しつつ、荷重が小さいことにより消費電力の低減が図れると共に、被加熱材である記録紙（記録媒体）において紙しわやカールが発生することを防止できるといった効果を奏する。
【０２６８】
本発明の画像形成装置は、以上のように、被加熱材上に未定着のトナーからなる画像を形成する像転写装置と、被加熱材上の未定着のトナーを定着させる上記記載の加熱装置とを備える構成である。
【０２６９】
これにより、消費電力の小さな画像形成装置を提供することができる。また、例えば、加熱装置を定着装置として用いることができる。従って、トナーの定着性を確保しつつ、荷重が小さいことにより消費電力の低減が図れると共に、被加熱材である記録紙（記録媒体）において紙しわやカールが発生することを防止できる。
【０２７０】
さらに、加熱部材や駆動部品の長寿命化を図ることができる加熱装置を用いた画像形成装置を提供できるといった効果を奏する。
【０２７１】
本発明の加熱方法は、以上のように、第１加熱部材と第２加熱部材とが圧接する圧接領域を、被加熱材の任意の一点が２．３×１０^−２秒以内に通過するように上記被加熱材を通過させることにより、上記被加熱材を加熱する加熱方法であって、上記第１加熱部材の表面温度をＴ１（℃）とし、上記第２加熱部材の表面温度をＴ２（℃）とすると、上記表面温度Ｔ１・Ｔ２が、Ｔ１−Ｔ２≦１００（℃）を満足するように、上記第２加熱部材を、該第２加熱部材の外側から外部加熱部材により加熱する構成である。
【０２７２】
あるいは、本発明の加熱方法は、第１および第２加熱部材の表面温度Ｔ１・Ｔ２が、Ｔ１−Ｔ２≦７０（℃）を満足するように、第２加熱部材を、該第２加熱部材の外側から外部加熱部材により加熱する構成である。
【０２７３】
これにより、被加熱材上の任意の一点が圧接領域を通過する通過時間が２．３×１０^−２秒以下の高速機であっても、圧接領域の面圧を大きくしなくてすむ。即ち、加熱部材にかかる荷重を小さくすることができる。
【０２７４】
従って、加熱部材の薄型化を図ることができ、熱容量を低減することができる。これにより、上記加熱方法を用いた加熱装置のウォームアップ時間を短縮することがでる。この結果、加熱部材を予熱する必要がなく、ウォームアップ時および待機時にかかる消費電力の低減を図ることができるといった効果を奏する。
【０２７５】
本発明の加熱方法は、外部加熱部材の表面温度を制御することにより、第１加熱部材の表面温度と第２加熱部材の表面温度との差を制御する構成である。
【０２７６】
これにより、第１加熱部材の表面温度と第２加熱部材の表面温度との差を簡単な構成で制御することができるといった効果を奏する。
【０２７７】
本発明の加熱方法は、圧接領域における被加熱材への面圧をＰ（ｋＰａ）とすると、第１加熱部材の表面温度Ｔ１（℃）と第２加熱部材の表面温度Ｔ２（℃）とは、Ｔ１−Ｔ２≦３０×ｌｎ（Ｐ）−７２．５を満足するように、表面温度Ｔ１およびＴ２を制御する構成である。
【０２７８】
これにより、加熱部材にかかる荷重を小さくすることができるといった効果を奏する。
【０２７９】
本発明の加熱方法は、以上のように、第１加熱部材と第２加熱部材とが圧接する圧接領域を、被加熱材の任意の一点が２．３×１０^−２秒以内に通過するように上記被加熱材を通過させることにより、上記被加熱材を加熱する加熱方法であって、上記圧接領域において上記被加熱材の通過時に、上記第１加熱部材から上記被加熱材に伝達される熱量をＱ１とし、上記第２加熱部材から上記被加熱材に伝達される熱量をＱ２とすると、上記熱量Ｑ１・Ｑ２が、Ｑ２／（Ｑ１＋Ｑ２）≧０．２５を満足するように制御する構成である。
【０２８０】
あるいは、本発明の加熱方法は、熱量Ｑ１・Ｑ２が、Ｑ２／（Ｑ１＋Ｑ２）≧０．３を満足するように制御する構成である。
【０２８１】
これにより、加熱部材の温度ではなく、被加熱材に伝達される熱量について規定しているため、加熱部材がどのような材料からなるものであっても、上述した第１加熱部材の表面温度Ｔ１および第２加熱部材の表面温度Ｔ２がＴ１−Ｔ２≦７０（℃）を満足するように規定した場合と同様の効果を得ることができる。即ち、加熱部材にかかる荷重を小さくすることができ、消費電力の低減を図ることができるといった効果を奏する。
【０２８２】
本発明の加熱方法は、第２加熱部材を外側から加熱する外部加熱部材によって第２加熱部材の表面温度を制御することにより、第２加熱部材から被加熱材に伝達される熱量Ｑ２と、被加熱材に伝達される総熱量Ｑ１＋Ｑ２との比Ｑ２／（Ｑ１＋Ｑ２）を制御する構成である。
【０２８３】
これにより、外部加熱部材によりＱ２／（Ｑ１＋Ｑ２）を制御することができる。従って、簡単な構成で、Ｑ２／（Ｑ１＋Ｑ２）の制御を可能とすることができるといった効果を奏する。
【０２８４】
本発明の加熱方法は、圧接領域における上記被加熱材への面圧をＰ（ｋＰａ）とすると、上記第２加熱部材から上記被加熱材に伝達される熱量Ｑ２（Ｊ）と、上記被加熱材に伝達される総熱量Ｑ１＋Ｑ２（Ｊ）との比Ｑ２／（Ｑ１＋Ｑ２）は、Ｑ２／（Ｑ１＋Ｑ２）≧−０．０７８×ｌｎ（Ｐ）＋０．７を満足するように、制御されている構成である。
【０２８５】
これにより、第２加熱部材から被加熱材に伝達される熱量Ｑ２の割合を大きくすることができ、必要定着荷重を低減することができる。従って、消費電力の低減を図ることができるといった効果を奏する。
【図面の簡単な説明】
【図１】本発明の実施の一形態に係る定着装置の要部の構成を示す図である。
【図２】必要面圧（ｋＰａ）と、加熱ローラの表面温度Ｔ１と加圧ローラの表面温度Ｔ２との温度差（℃）との関係を示すグラフである。
【図３】ウォームアップ時間（秒）およびエネルギー消費効率（Ｗｈ／ｈ）と、加熱ローラの表面温度Ｔ１と加圧ローラの表面温度Ｔ２との温度差（℃）との関係を示すグラフである
【図４】加熱ローラにおける軸方向の単位長さ当りの熱容量（Ｊ／ｍ℃）と、ウォームアップ時間（秒）との関係について示すグラフ
【図５】必要面圧Ｐ（ｋＰａ）と、加圧ローラから記録紙Ｐに伝わる熱エネルギーＱ２の総熱量Ｑ１＋Ｑ２に対する割合Ｑ２／Ｑ１＋Ｑ２との関係を示すグラフである。
【図６】ウォームアップ時間およびエネルギー消費効率と、総熱量Ｑ１＋Ｑ２に対する熱量Ｑ２の割合Ｑ２／Ｑ１＋Ｑ２との間の関係を示すグラフである。
【図７】本発明の実施の他の一形態に係る定着装置の要部の構成を示す図である。
【図８】図８は、図１に示す定着装置を備えた画像形成装置を外側から見た構成を示す斜視図である。
【図９】上記画像形成装置の内部の構成を示す図である。
【図１０】上記画像形成装置における原稿画像読取装置の構成を示す図である。
【図１１】上記画像形成装置における画像記録装置の構成を示す図である。
【図１２】上記画像形成装置における記録材供給装置の構成を示す図である。
【図１３】上記画像形成装置における外部記録材供給装置の構成を示す図である。
【図１４】上記画像形成装置における後処理装置の構成を示す図である。
【図１５】上記画像形成装置における両面印刷用搬送部の構成を示す図である。
【図１６】従来の中低速機および高速機でのニップ通過時間と、ローラ温度および定着ニップ部を通過する記録紙にかかる面圧との関係を示したグラフである。
【符号の説明】
２３ 定着装置
２３１ 加熱ローラ（第１加熱部材）
２３２ 加圧ローラ（第２加熱部材）
２３２ｄ 発熱層（発熱体）
２３３ 外部加熱ローラ（外部加熱部材）
２３４，２３５，２３９ ヒータランプ（熱源体）
２３６，２３７，２４２，２４９ 温度センサ（温度検出手段）
２４０ クリーニングローラ
２４１ 誘導加熱コイル（外部加熱部材）
Ｙ 定着ニップ部（圧接領域）
Ｐ 記録紙（被加熱材、記録媒体）
Ｔ トナー[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heating device for heating a medium by heat and pressure, an image forming apparatus including the heating device, and a heating method.
[0002]
[Prior art]
When a heating device that heats a medium by heat and pressure is used as a fixing device that fixes a developer on a recording medium in an electrophotographic image forming apparatus such as a copying machine or a printer, a heating roller fixing method is generally used. Is often used.
[0003]
A fixing device having a heat roller fixing system includes a pair of rollers (a heating roller and a pressure roller) pressed against each other. Further, a heating means such as a halogen heater is provided inside a roller (heating roller) in contact with the toner image surface side of the recording medium (recording paper).
[0004]
Then, after the heating roller is heated to a predetermined temperature (fixing temperature) by the heating means, the recording medium on which the unfixed toner image is formed is passed through a pressure contact portion (fixing nip portion) between the heating roller and the pressure roller. Then, the toner image is fixed by heat and pressure.
[0005]
However, in this heat roller fixing method, the time (warm-up time) from when the heating of the heating roller starts to when the heating roller reaches the fixing temperature is long. Therefore, it is necessary to preheat the heating roller even during standby from the viewpoint of usability, so that there is a problem that a large amount of power is consumed during warm-up and during standby.
[0006]
In order to solve such a problem, a fixing device using a thin-walled heat roller fixing system has been proposed in recent years (for example, see Patent Document 1).
[0007]
In the fixing device of the thin heat roller fixing method, the core of the heating roller is thinned, and the heat capacity of the heating roller is reduced. As a result, the warm-up time can be reduced, and power consumption during warm-up and standby can be reduced.
[0008]
[Patent Document 1]
JP-A-9-244448 (published on September 19, 1997)
[0009]
[Problems to be solved by the invention]
However, the thin heat roller fixing method can reduce the thickness of the heating roller in a medium-to-low speed machine (for example, when the A4 size recording paper is horizontally fed and the copy speed is less than 50 sheets / min), but the high speed machine ( For example, when the A4 size recording paper is fed horizontally and the copy speed is 50 sheets / min or more), it is difficult to reduce the thickness of the heating roller.
[0010]
Therefore, in a high-speed machine, the warm-up time is long (usually 3 minutes or more), and the power consumption increases. The reason why it is difficult to reduce the thickness of the heating roller with a high-speed machine will be described below with reference to FIG.
[0011]
FIG. 16 is a graph showing the relationship between the nip passage time in a conventional medium-speed machine and high-speed machine, the temperature of the heating roller (roller temperature), and the pressure (surface pressure) applied to the recording paper passing through the fixing nip. is there.
[0012]
Here, the nip transit time is also called a dwell time, and is a value obtained by dividing the width of the fixing nip by the fixing speed (recording paper conveyance speed), and it is necessary for any one point on the recording paper to pass through the fixing nip. Indicates the time required. Therefore, normally, the higher the copy speed, the shorter the nip passage time.
[0013]
As shown in FIG. 16, in the medium-to-low speed machine, the copy speed is increased and the reduced nip transit time is covered by increasing the fixing roller temperature, thereby giving a necessary amount of heat to the recording paper and sufficient fixability. You can see that it is secured. Therefore, the surface pressure is almost constant regardless of the nip passing time.
[0014]
However, since the fixing speed of the high-speed machine is higher than that of the medium-low-speed machine, the nip passing time is 23 msec (2.3 × 10 ^-2 Seconds) or less. On the other hand, the always-used temperature of the heating roller generally has a limit (for example, 200 ° C.). Therefore, the temperature of the heating roller cannot be increased to the limit temperature or more due to the problem of heat resistance of the heating roller. For this reason, in the high-speed machine, the fixing property is secured by setting the surface pressure to be high while the heating roller temperature is kept constant (limit temperature).
[0015]
For this reason, since a large load is applied to the heating roller, it is not possible to reduce the thickness of the heating roller in a high-speed machine as in a medium-to-low-speed machine, and therefore, it is difficult to shorten a warm-up time, and power consumption is reduced. growing.
[0016]
In addition, when a large load is applied to the heating roller, creep and reduction in roller life of the heating roller occur, and paper wrinkles and curls occur on the recording paper.
[0017]
Further, it is difficult to reduce the thickness of the heating roller, which leads to an increase in the size of the apparatus. In addition, the driving torque of the heating roller increases, which leads to an increase in power consumption and a reduction in the life of the driving parts.
[0018]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a heating device capable of reducing a load applied to a heating roller and reducing power consumption, an image forming apparatus including the heating device, and a heating device. It is to provide a method.
[0019]
[Means for Solving the Problems]
In order to solve the above-described problems, a heating device of the present invention includes a first heating member and a second heating member that are in pressure contact with each other, and covers a pressure contact region in which the first heating member and the second heating member are in pressure contact with each other. In the heating device in which the heating material is heated by passing the heating material, the heating device includes an external heating member that heats the second heating member from outside the second heating member. The time required for one point to pass through the pressure contact area is 2.3 × 10 ^-2 Second or less, and assuming that the surface temperature of the first heating member is T1 (° C.) and the surface temperature of the second heating member is T2 (° C.), the surface temperatures T1 and T2 are T1−T2 ≦ 100 ( ° C).
[0020]
In the above heating device, it is further preferable that the surface temperature T1 of the first heating member and the surface temperature T2 of the second heating member satisfy T1−T2 ≦ 70 (° C.).
[0021]
According to the above configuration, the surface temperature T1 (° C.) of the first heating member and the surface temperature T2 of the second heating member are T1-T2 ≦ 100 (° C.) or T1-T2 ≦ 70 (° C.) Is satisfied, the passage time of an arbitrary point on the material to be heated passing through the pressure contact area is 2.3 × 10 3 ^-2 Even with a high-speed machine of less than a second, it is not necessary to increase the surface pressure in the pressure contact area. That is, the load applied to the heating member can be reduced.
[0022]
Therefore, the thickness of the heating member can be reduced, and the heat capacity can be reduced. Thereby, the warm-up time of the heating device can be reduced. As a result, it is not necessary to preheat the heating member, and it is possible to reduce power consumption during warm-up and standby.
[0023]
Further, since the load applied to the heating member is small, it is possible to prevent, for example, generation of creep and shortening of the life of the heating member.
[0024]
Further, since the thickness of the heating member can be reduced, the size of the heating device can be reduced. Further, since the driving torque of the heating member can be reduced, the power consumption can be reduced, and the life of the driving parts can be prevented from being shortened.
[0025]
In the above heating device, it is preferable that the difference between the surface temperature of the first heating member and the surface temperature of the second heating member is controlled by an external heating member.
[0026]
Specifically, the above-described heating device includes a temperature detection unit that detects a surface temperature of the external heating member, and a control unit that controls the surface temperature of the external heating member based on a detection result of the temperature detection unit. Is preferred.
[0027]
According to the above configuration, since the external heating member heats the second heating member from outside the second heating member, the surface temperature of the second heating member can be easily controlled.
[0028]
Therefore, the difference between the surface temperature of the first heating member and the surface temperature of the second heating member can be controlled with a simple configuration.
[0029]
It is preferable that the heating device is controlled so that the surface temperature of the first heating member is kept substantially constant.
[0030]
According to the above configuration, since the surface temperature of the first heating member is kept substantially constant, the difference between the surface temperature of the first heating member and the surface temperature of the second heating member is determined by the external heating member. It can be controlled only by the surface temperature of the member.
[0031]
When the surface pressure on the material to be heated in the pressure contact region is P (kPa), the above-described heating device has a surface temperature T1 (° C.) of the first heating member and a surface temperature T2 (° C.) of the second heating member. , T1−T2 ≦ 30 × ln (P) −72.5.
[0032]
According to the above configuration, T1-T2 can be reduced, and the amount of heat transmitted to the material to be heated can be increased. Therefore, the load applied to the heating member can be reduced.
[0033]
In order to solve the above-described problems, a heating device of the present invention includes a first heating member and a second heating member that are in pressure contact with each other, and heats a pressure contact area where the first heating member and the second heating member are in pressure contact with each other. In the heating device in which the material to be heated is heated by the passage of the material, the time required for any one point on the material to be heated to pass through the pressure contact area is 2.3 × 10 ^-2 Second or less, and the amount of heat transmitted from the first heating member to the material to be heated when passing through the material to be heated is Q1, and the amount of heat transmitted from the second heating member to the material to be heated is Q2. Then, the heat quantity Q1 and the heat quantity Q2 are characterized by satisfying Q2 / (Q1 + Q2) ≧ 0.25.
[0034]
Further, in the above-described heating device, it is preferable that the heat quantity Q1 and the heat quantity Q2 satisfy Q2 / (Q1 + Q2) ≧ 0.3.
[0035]
For example, even if the surface temperature of the second heating member is maintained at a high temperature, if the thermal conductivity of the material forming the second heating member is extremely low, a sufficient amount of heat is supplied from the second heating member to the material to be heated. Not transmitted and heating may be insufficient.
[0036]
However, according to the above configuration, not the temperature of the heating member but the amount of heat transmitted to the material to be heated is specified. The same effect as in the case where the surface temperature T1 of the heating member and the surface temperature T2 of the second heating member are defined so as to satisfy T1−T2 ≦ 70 (° C.) can be obtained.
[0037]
That is, the load applied to the heating member can be reduced, and power consumption can be reduced.
[0038]
The above-described heating device transmits the second heating member from the second heating member to the material to be heated by controlling the surface temperature of the external heating member and the external heating member that heats the second heating member from outside the second heating member. It is preferable to include control means for controlling a ratio Q2 / (Q1 + Q2) of the heat quantity Q2 to be heated and the total heat quantity Q1 + Q2 transmitted to the material to be heated.
[0039]
According to the above configuration, Q2 / (Q1 + Q2) can be controlled by the external heating member. Therefore, it is possible to control Q2 / (Q1 + Q2) with a simple configuration.
[0040]
In the above heating device, when the surface pressure on the material to be heated in the pressure contact region is P (kPa), the amount of heat Q2 (J) transmitted from the second heating member to the material to be heated and the amount of heat transmitted to the material to be heated. It is preferable that the ratio Q2 / (Q1 + Q2) to the total amount of heat Q1 + Q2 (J) satisfies Q2 / (Q1 + Q2) ≧ −0.078 × ln (P) +0.7.
[0041]
According to the above configuration, Q2 / (Q1 + Q2) (that is, the ratio of the amount of heat Q2 transmitted from the second heating member to the material to be heated) can be increased, and the required fixing load can be reduced. Therefore, power consumption can be reduced.
[0042]
In the above heating device, it is preferable that the surface pressure on the material to be heated in the pressure contact region is 300 (kPa) or less.
[0043]
According to the above configuration, the load applied to the heating member and the material to be heated can be reduced.
[0044]
In the above heating device, it is preferable that the external heating member has a heat source body and heats the second heating member by being in contact with the surface of the second heating member.
[0045]
According to the above configuration, since the surface of the second heating member can be directly heated, the configuration of the external heating member can be simplified, and the space can be saved. Therefore, it is possible to easily install other components such as a cleaning roller.
[0046]
In the above-described heating device, it is preferable that the external heating member is a roller that is circumscribed with the second heating member and rotates together with the second heating member.
[0047]
According to the above configuration, the second heating member can be heated with a simple configuration. Therefore, space can be saved, and other components such as a cleaning member can be easily installed.
[0048]
In the above-described heating device, it is preferable that the second heating member includes a heating element that generates heat by induction heating, and the external heating member is an induction heating coil that performs induction heating of the second heating member.
[0049]
According to the above configuration, since the second heating member can directly generate heat, heat loss due to radiation and convection from the surface of the second heating member is small. Further, since the external heating member itself hardly generates heat, heat loss of the external heating member itself is small. Therefore, the thermal efficiency can be further improved.
[0050]
In the above heating device, it is preferable that the shape of the external heating member has a curvature.
[0051]
According to the above configuration, the magnetic flux concentrates on the center side of the induction heating coil as the external heating member, and the amount of eddy current generated increases. Therefore, the rise of heat generation of the second heating member can be made faster.
[0052]
In the above heating device, the surface of the first heating member preferably has a heat capacity per unit length of 200 J / (m · ° C.) or less.
[0053]
According to the above configuration, for example, the warm-up time can be set to 30 seconds or less, and the power consumption during standby can be significantly reduced.
[0054]
It is preferable that the heating device is a roller in which the first heating member and the second heating member are rotatable, and the toner on the heated material is fixed by passing the heated material through the pressure contact area.
[0055]
According to the above configuration, the heating device can be used as a fixing device. Therefore, the power consumption can be reduced due to the small load while securing the fixing property of the toner, and wrinkles and curls can be prevented from occurring on the recording paper (recording medium) as the material to be heated.
[0056]
An image forming apparatus according to the present invention includes: an image transfer device that forms an image made of unfixed toner on a material to be heated; and the above-described heating device that fixes unfixed toner on a material to be heated. Features.
[0057]
According to the above configuration, it is possible to provide an image forming apparatus with low power consumption. Further, for example, a heating device can be used as a fixing device. Accordingly, the power consumption can be reduced due to the small load while securing the fixing property of the toner, and wrinkles and curls can be prevented from occurring on the recording paper as the material to be heated.
[0058]
Further, it is possible to provide an image forming apparatus using a heating device capable of extending the life of the heating member and the driving components.
[0059]
According to the heating method of the present invention, in order to solve the above-mentioned problem, an arbitrary point of the material to be heated is set at 2.3 × 10 ^-2 A heating method for heating the material to be heated by passing the material to be heated so as to pass within seconds, wherein the surface temperature of the first heating member is T1 (° C.), and the second heating member is When the surface temperature of the second heating member is T2 (° C.), the second heating member is externally heated from outside the second heating member so that the surface temperature T1 · T2 satisfies T1−T2 ≦ 100 (° C.). It is characterized by heating by a member.
[0060]
Further, the above-mentioned heating method includes the steps of: placing the second heating member outside the second heating member so that the surface temperatures T1 and T2 of the first and second heating members satisfy T1−T2 ≦ 70 (° C.). It is more preferable to heat with an external heating member.
[0061]
According to the above method, the surface temperature T1 (° C.) of the first heating member and the surface temperature T2 of the second heating member are T1−T2 ≦ 100 (° C.) or T1−T2 ≦ 70 (° C.) Is satisfied, the passage time of an arbitrary point on the material to be heated passing through the pressure contact area is 2.3 × 10 3 ^-2 Even with a high-speed machine of less than a second, it is not necessary to increase the surface pressure in the pressure contact area. That is, the load applied to the heating member can be reduced.
[0062]
Therefore, the thickness of the heating member can be reduced, and the heat capacity can be reduced. Thereby, the warm-up time of the heating device using the above-described heating method can be reduced. As a result, it is not necessary to preheat the heating member, and it is possible to reduce power consumption during warm-up and standby.
[0063]
In the above-described heating method, it is preferable to control the difference between the surface temperature of the first heating member and the surface temperature of the second heating member by controlling the surface temperature of the external heating member.
[0064]
According to the above method, the difference between the surface temperature of the first heating member and the surface temperature of the second heating member can be controlled with a simple configuration.
[0065]
In the above-mentioned heating method, when the surface pressure on the material to be heated in the pressure contact region is P (kPa), the surface temperature T1 (° C.) of the first heating member and the surface temperature T2 (° C.) of the second heating member are: It is preferable to control the surface temperatures T1 and T2 so as to satisfy T1−T2 ≦ 30 × ln (P) −72.5.
[0066]
According to the above method, T1-T2 can be reduced, and the amount of heat transferred to the material to be heated can be increased. Therefore, the load applied to the heating member can be reduced.
[0067]
According to the heating method of the present invention, in order to solve the above-mentioned problem, an arbitrary point of the material to be heated has a pressure contact area where the first heating member and the second heating member press against each other at 2.3 × 10 3. ^-2 A heating method for heating the material to be heated by passing the material to be heated so that the material to be heated is passed within seconds. Assuming that the amount of heat transmitted to the heating material is Q1, and the amount of heat transmitted from the second heating member to the material to be heated is Q2, the amount of heat Q1 · Q2 satisfies Q2 / (Q1 + Q2) ≧ 0.25. Is controlled in such a manner.
[0068]
Further, in the above-described heating method, it is preferable to control the heat amounts Q1 and Q2 so as to satisfy Q2 / (Q1 + Q2) ≧ 0.3.
[0069]
According to the above method, since the amount of heat transmitted to the material to be heated is defined instead of the temperature of the heating member, the first heating member described above can be used regardless of what material the heating member is made of. The same effect as in the case where the surface temperature T1 and the surface temperature T2 of the second heating member are defined so as to satisfy T1−T2 ≦ 70 (° C.) can be obtained. That is, the load applied to the heating member can be reduced, and power consumption can be reduced.
[0070]
The above heating method controls the surface temperature of the second heating member by an external heating member that heats the second heating member from the outside, so that the heat quantity Q2 transmitted from the second heating member to the material to be heated, It is preferable to control the ratio Q2 / (Q1 + Q2) to the total amount of heat Q1 + Q2 transmitted to the material.
[0071]
According to the above method, Q2 / (Q1 + Q2) can be controlled by the external heating member. Therefore, it is possible to control Q2 / (Q1 + Q2) with a simple configuration.
[0072]
In the above heating method, assuming that the surface pressure on the material to be heated in the pressure contact region is P (kPa), the amount of heat Q2 (J) transmitted from the second heating member to the material to be heated and the material to be heated are Is controlled so that the ratio Q2 / (Q1 + Q2) to the total amount of heat Q1 + Q2 (J) transmitted to the motor satisfies Q2 / (Q1 + Q2) ≧ −0.078 × ln (P) +0.7. preferable.
[0073]
According to the above method, the ratio Q2 / (Q1 + Q2) (that is, the ratio of the amount of heat Q2 transmitted from the second heating member to the material to be heated) can be increased, and the required fixing load can be reduced. Therefore, power consumption can be reduced.
[0074]
BEST MODE FOR CARRYING OUT THE INVENTION
[Embodiment 1]
One embodiment of the present invention is described below with reference to FIGS. 1 to 6 and FIGS. 8 to 15.
[0075]
FIG. 1 shows a configuration of a main part of a fixing device (heating device) 23 according to the present embodiment. As shown in the figure, the fixing device 23 includes a heating roller (first heating member) 231, a pressure roller (second heating member) 232, an external heating roller (external heating member) 233, and a cleaning roller 240. ing.
[0076]
Hereinafter, an example of a configuration when the fixing device 23 is applied to an electrophotographic copying machine will be described. The fixing device 23 fixes the toner T on the recording paper P by applying heat and pressure to the recording paper P on which the image formed of the unfixed toner T is formed.
[0077]
As shown in FIG. 1, the heating roller 231 is a roller that is rotatable in the direction of arrow A in the figure, and a fixing nip portion Y described later (when the heating roller 231 and the pressure roller 232 described later contact the recording paper P). To heat the recording paper P passing through the area where the toner T is fixed on the recording paper P). The heating roller 231 includes a cylindrical core 231a and a release layer 231b.
[0078]
The core metal 231a is a main body of the heating roller 231 and has a hollow cylindrical shape. As the material of the cored bar 231a, it is preferable to use metals such as iron, aluminum, and copper, or alloys thereof, and for example, stainless steel and carbon steel. Here, as the core 231a, a core made of iron (STKM (carbon steel)) having a diameter of 40 mm and a thickness of 0.4 mm to reduce heat capacity is used.
[0079]
The release layer 231b is formed on the outer peripheral surface of the cored bar 231a in order to prevent the toner T on the recording paper P from being offset. As a material of the release layer 231b, a fluororesin such as PFA (perfluoroalkoxyalkane: a copolymer of tetrafluoroethylene and perfluoroalkylvinyl ether) or PTFE (polytetrafluoroethylene), a silicone rubber, a fluororubber, or the like is suitable. ing. Here, the release layer 231b is formed by applying a mixture of PFA and PTFE to a core metal 231a to a thickness of 25 μm and firing it.
[0080]
In addition, heater lamps 234 and 235 (heating sources) including halogen heaters are arranged in the core metal 231 a of the heating roller 231. The heater lamps 234 and 235 emit light with a predetermined heat generation distribution and emit infrared rays when energized by a control circuit (not shown). Thereby, the inner peripheral surface of the heating roller 231 is heated.
[0081]
That is, the heating roller 231 is heated by the heater lamps 234 and 235 to a predetermined temperature (here, 200 ° C.). Thereby, the recording paper P on which the unfixed toner image passing through the fixing nip portion (pressure contact area) Y is formed can be heated, and therefore, the toner T can be melted and fixed on the recording paper P. Here, the total rated output of the heater lamps 234 and 235 is 700 W.
[0082]
Further, a guide portion 238 is provided near the outer periphery of the heating roller 231 and downstream of the vicinity of the fixing nip portion Y to guide the recording paper P on which the toner T is fixed so as to be separated from the heating roller 231.
[0083]
The pressure roller 232 is a roller that can rotate in the direction of arrow B in the figure, and is pressed against the heating roller 231 with a force of, for example, 274N by a pressure member such as a spring (not shown). Thus, a fixing nip portion Y having a width of about 7 mm is formed between the heating roller 231 and the heating roller 231. The pressure roller 232 includes a metal core 232a, a heat-resistant elastic layer 232b, and a release layer 232c.
[0084]
The core metal 232a is a main body of the pressure roller 232 and has a hollow cylindrical shape. It is preferable to use a metal such as iron or aluminum, or an alloy thereof, for example, as the material of the cored bar 232a. For example, stainless steel or carbon steel is used. Here, here, it is assumed that a stainless steel core having a diameter of 28 mm is used as the core 232a.
[0085]
The heat-resistant elastic layer 232b is formed on the outer peripheral surface of the cored bar 232a, and is made of foamed silicone rubber having a thickness of 6 mm. That is, the heat-resistant elastic layer 232b has elasticity so that it can be deformed by the pressure from the pressure member, and has resistance to heating from the external heating roller 233 described later.
[0086]
The release layer 232c is formed on the surface of the heat-resistant elastic layer 232b and is made of, for example, a 50 μm-thick PFA tube made of a fluororesin. The release layer 232c has a release property.
[0087]
The external heating roller 233 has a heater lamp (heat source body) 239 therein and heats the pressure roller 232. The configuration of the heater lamp 239 is the same as the configuration of the heater lamps 234 and 235 described above, and the rated output is 300 W here. The external heating roller 233 is arranged on the upstream side of the fixing nip portion Y with respect to the pressure roller 232, and presses with a predetermined pressing force.
[0088]
When the external heating roller 233 is pressed against the pressure roller 232 with a predetermined pressing force, a heating nip Z is formed between the external heating roller 233 and the pressure roller 232. Here, the width of the heating nip portion Z (the length in the direction of arrow B in the figure) is 3 mm.
[0089]
The external heating roller 233 includes a core bar 233a and a heat-resistant release layer 233b. The core bar 233a is a main body of the external heating roller 233, and is preferably made of a metal such as iron, aluminum, or copper, or an alloy thereof. Here, as the core metal 233a, an aluminum cylindrical shaft having a diameter of 15 mm and a thickness of 0.5 mm is used.
[0090]
As the material of the heat-resistant release layer 233b, a synthetic resin material having excellent heat resistance and release properties, for example, an elastomer such as silicone rubber or fluoro rubber, or a fluoro resin such as PFA or PEFE is used. Here, as the material of the heat-resistant release layer 233b, a material obtained by blending PFA and PEFE is used, and this material is coated on a cored bar 233a to a thickness of 25 μm and fired to form a heat-resistant release layer. A layer 233b is to be formed.
[0091]
A temperature sensor (temperature detecting means) 237 for detecting the temperature of the surface of the heating roller 231 is provided near the outer periphery of the heating roller 231. Based on the temperature detected by the temperature sensor 237, a control circuit (control means) (not shown) controls the energization of the heater lamps 234 and 235 so that the surface temperature of the heating roller 231 becomes a predetermined temperature.
[0092]
A temperature sensor (temperature detecting means) 242 for detecting the temperature of the surface of the pressure roller 232 is arranged near the outer periphery of the pressure roller 232. A temperature sensor (temperature detecting means) 236 for detecting the surface temperature of the external heating roller 233 is disposed near the outer periphery of the external heating roller 233.
[0093]
A control circuit (control means) (not shown) calculates the surface temperature of the external heating roller 233 based on the surface temperature of the pressure roller 232 detected by the temperature sensor 242 and the surface temperature of the external heating roller 233 detected by the temperature sensor 236. Is controlled to a predetermined temperature. Thus, by controlling the energization of the heater lamp 239, the surface temperature of the pressure roller 232 and the surface temperature of the external heating roller 233 are controlled.
[0094]
For example, the temperature condition of the external heating roller 233 is determined in advance so that the temperature difference between the surface temperature of the heating roller 231 and the surface temperature of the pressure roller 232 becomes a desired value. When a method of controlling the temperature of the roller 233 is used, the temperature sensor 242 may be omitted.
[0095]
A cleaning roller 240 is disposed around the pressure roller 232 on the upstream side of the external heating roller 233.
[0096]
The cleaning roller 240 is for removing toner, paper dust, and the like attached to the pressure roller 232 and preventing the external heating roller 233 from being stained. Further, the cleaning roller 240 is provided on the upstream side of the heating nip Z with the pressure roller 232, and is configured to be in pressure contact with a predetermined pressing force.
[0097]
Further, the cleaning roller 240 is supported so as to rotate following the rotation of the pressure roller 232. The cleaning roller 240 is a core material made of a metal such as aluminum or stainless steel, and has a cylindrical shape. Here, stainless steel is used as the material of the cleaning roller 240.
[0098]
Note that the configurations (for example, materials, sizes, shapes, and the like) of the heating roller 231, the pressure roller 232, the external heating roller 233, and the cleaning roller 240 are not particularly limited to the above-described configurations.
[0099]
Here, the operation of the fixing device 23 will be described. As shown in FIG. 1, a recording sheet P on which an image made of unfixed toner T is formed is conveyed in the direction of arrow C in FIG. The recording paper P is heated by the heater lamps 234 and 235 to 200 ° C. and heated by the external heating roller 233 to a predetermined temperature, and the pressing roller 232 pressed against the heating roller 231. , Ie, passes through the fixing nip portion Y.
[0100]
At this time, the unfixed toner T is melted and pressed on the recording paper P by the heat and pressure from the rollers 231 and 232. Thus, the fixing device 23 having the above configuration can fix the toner T on the recording paper P passing between the rollers 231 and 232.
[0101]
The time required for an arbitrary point on the recording paper P to pass through the fixing nip portion Z, that is, the width (mm) of the fixing nip portion Y / the transport (fixing) speed (mm / sec) of the recording paper P is expressed by: Assuming the nip passing time, the nip passing time in the present embodiment is 23 milliseconds or less.
[0102]
A copying machine is generally driven in a copy mode, a warm-up mode, a standby mode, or the like.
[0103]
The warm-up mode is a mode in which the copying machine is turned on after the power of the copying machine is turned on. In this mode, the copier first energizes the heater lamps 234 and 235 and heats the heating roller 231 until the heating roller 231 reaches a predetermined temperature (here, 200 ° C.). When the temperature of the heating roller 231 reaches a predetermined temperature, the drive motor is turned ON, and the rollers 231 232 233 are driven to rotate at a peripheral speed (fixing speed) of 365 mm / sec. Then, heating is performed until the external heating roller 233 reaches a predetermined temperature (here, 170 ° C.).
[0104]
The copy mode is a mode for forming an image on the recording paper P, and the fixing device 23 fixes toner on the recording paper P in this mode. In the copy mode, the heater lamps 234, 235, and 239 are set so that the heating roller 231 and the pressing roller 232 maintain a predetermined temperature (here, the heating roller 231 is 200 ° C., and the pressing roller 232 is 135 ° C.). Is controlled.
[0105]
That is, the heater lamp 239 of the external heating roller 233 is set to a temperature required to maintain the surface temperature of the pressure roller 232 at a predetermined temperature (here, 135 ° C.). (Here, 170 ° C.).
[0106]
The standby mode is a mode in which the power is maintained so that the copying machine can immediately shift to the copy mode when a printing request is made in the copying machine. After the copying is completed, the standby mode is maintained for a while until the mode shifts to the low power mode.
[0107]
In order to fix the toner T on the recording paper P, a certain surface pressure between the heating roller 231 and the pressure roller 232 in the fixing nip Y is required. That is, it is necessary that a load for fixing the toner T be applied to the recording paper P passing through the fixing nip Y.
[0108]
Hereinafter, a relationship between a load required for fixing the toner T (hereinafter, referred to as a necessary fixing load), a surface temperature T1 of the heating roller 231 and a surface temperature T2 of the pressure roller 232 will be described with reference to Table 1. explain. The surface temperature T1 of the heating roller 231 is set to 200 ° C. Further, a value obtained by dividing the required fixing load (N) by the area of the fixing nip Y where the toner T is fixed is referred to as a required surface pressure (kPa).
[0109]
Here, in the fixing device 23, the surface temperature T2 of the pressure roller 232 is set at 105 ° C., the configuration (1), the configuration at 130 ° C. is configured (2), and the configuration at 135 ° C. is configured (3). And
[0110]
In addition, as a comparative example, a configuration in which the external heating roller 233 is not provided and the pressure roller 232 is not heated is described in Comparative Examples (1) and (2). A comparative example (3) in which a heater lamp is provided inside and the heating roller 232 is heated by the heater lamp.
[0111]
[Table 1]

[0112]
In the comparative examples (2) and (3), and the configurations (1) to (3), the nip passing time is 19.2 milliseconds (msec) (transport paper is fed by using an A4 size recording paper P). , The copy speed is 65 sheets / min), and the width of the fixing nip portion Y (the length in the direction of arrow A in the figure) (the fixing nip width) is 7 mm. In Comparative Example (1), the nip passage time is 17.8 milliseconds and the fixing nip width is 6.5 mm.
[0113]
As shown in Table 1, it is understood that the comparative examples (1) and (2) in which the pressure roller 232 is not heated require a very high surface pressure (360 kPa or more).
[0114]
This is because, despite the fact that the surface temperature T1 of the heating roller 231 is controlled to the limit temperature of 200 ° C., the nip passage time is very short, so that the heat energy necessary for melting the toner is generated from the heating roller 231. This is because it does not reach the recording paper P. Further, since the pressure roller 232 does not have a heat source (for example, heating means such as an external heating roller 233 or a heater lamp), the surface temperature T2 of the pressure roller 232 is 100 ° C. or less (that is, T1−T2> 100). ° C (deg))), and the heat energy transmitted from the pressure roller 232 to the recording paper P is small, and a very high fixing load is required to compensate for this.
[0115]
On the other hand, by providing a heating means (external heating roller 233 or heater lamp) for heating the pressure roller 233 as in the comparative example (3) and the configurations (1) to (3), the surface temperature of the pressure roller 232 is increased. If T2 is maintained in a high temperature state (that is, T1−T2 ≦ 100 (° C. (deg))), the heat energy transmitted from the pressure roller 232 to the recording paper P increases, so that the required fixing load is reduced to 300 kPa or less. can do.
[0116]
Here, FIG. 2 shows the relationship between the required surface pressure (kPa) shown in Table 1 and the difference (T1-T2 (° C.)) between the surface temperature T1 of the heating roller 231 and the surface temperature T2 of the pressure roller 232. It is a graph shown.
[0117]
As shown in the drawing, based on the comparative examples (1) to (3) and the configurations (1) to (3), the required surface pressure P (kPa) and the temperature difference T1− between the heating roller 231 and the pressure roller 232 are obtained. When the relationship with T2 (° C.) is approximated by the least squares method, it can be approximated as T1−T2 = 30 × ln (P) −72.5.
[0118]
Further, as described above, the smaller the temperature difference T1−T2 (° C.) between the heating roller 231 and the pressure roller 232 is, the more heat energy transmitted from the pressure roller 232 to the recording paper P increases, so that the necessary fixing Considering that the load can be reduced, the relationship between the required surface pressure P (kPa) and the temperature difference T1-T2 (° C.) between the heating roller 231 and the pressure roller 232 is expressed by the following equation (1). Is preferred.
[0119]
T1−T2 ≦ 30 × ln (P) −72.5 (1)
As described above, if the pressure roller 232 is heated and maintained by the external heating roller 233, a sufficient fixing property can be secured.
[0120]
As described above, the fixing device 23 includes the heating roller 231 and the pressure roller 232 that are in pressure contact with each other, and the fixing nip portion Y (pressure contact area) where the heating roller 231 and the pressure roller 232 are in pressure contact with each other. Then, the recording paper P is heated. Thus, the toner T on the recording paper P is fixed.
[0121]
The external heating roller 233 heats the pressure roller 232 from outside the pressure roller 232. The passage time of an arbitrary point on the recording paper P passing through the fixing nip portion Y is 2.3 × 10 ^-2 Seconds or less. That is, the fixing device 23 is applied to a high-speed machine. At this time, assuming that the surface temperature of the heating roller 231 is T1 (° C.) and the surface temperature of the pressure roller 232 is T2 (° C.), the surface temperatures T1 and T2 satisfy T1−T2 ≦ 100 (° C.). Alternatively, it is more preferable that T1−T2 ≦ 70 (° C.) is satisfied.
[0122]
According to the above configuration, it is not necessary to increase the surface pressure of the fixing nip portion Y even in a high-speed machine. That is, the load applied to the rollers 231 and 232 can be reduced.
[0123]
Therefore, it is possible to reduce the thickness of the roller, especially the heating roller 231, and to reduce the heat capacity. Thereby, the warm-up time of the fixing device 23 can be reduced. As a result, it is not necessary to preheat the fixing device 23, and power consumption during warm-up and standby can be reduced.
[0124]
Further, since the load applied to the rollers 231 and 232 is small, for example, it is possible to prevent the occurrence of creep and shortening of the life of the rollers 231 and 232.
[0125]
Further, since the thickness of the rollers 231 and 232 can be reduced, the size of the fixing device 23 can be reduced. Further, since the driving torque of the rollers 231 and 232 can be reduced, power consumption can be reduced, and shortening of the life of driving components can be prevented.
[0126]
The difference between the surface temperature of the heating roller 231 and the surface temperature of the pressure roller 232 is controlled by the external heating roller 233.
[0127]
Specifically, the fixing device 23 includes a temperature sensor 236 for detecting the surface temperature of the external heating roller 233 and a control unit (not shown) for controlling the surface temperature of the external heating roller 233 based on the detection result. Prepare.
[0128]
Thus, the surface temperature of the heating roller 231 and the surface temperature of the pressure roller 232 can be controlled with a simple configuration.
[0129]
On the other hand, the surface temperature of the heating roller 231 is controlled to be kept substantially constant.
[0130]
Thus, the difference between the surface temperature of the heating roller 231 and the surface temperature of the pressure roller 232 can be controlled by the external heating roller 233 only by the surface temperature of the pressure roller 232.
[0131]
Further, assuming that the surface pressure on the recording paper P at the fixing nip Y is P (kPa), the fixing device 23 determines the surface temperature T1 (° C.) of the heating roller 231 and the surface temperature T2 (° C.) of the pressure roller 232. Preferably satisfies T1−T2 ≦ 30 × ln (P) −72.5.
[0132]
Thereby, T1-T2 can be reduced, and the amount of heat transmitted to the recording paper P can be increased. Therefore, the load applied to the pressure roller 232 can be reduced.
[0133]
Next, a comparison between the warm-up time and the energy consumption efficiency will be made using Table 2 for the comparative example (3) and the configurations (1) to (3) described above. The thickness of the core metal 231a of the heating roller 231 was set so that the amount of deflection of the heating roller 231 was less than or equal to the allowable amount for each required fixing load. .
[0134]
[Table 2]

[0135]
FIG. 3 is a graph showing the relationship between the warm-up time and the energy consumption efficiency shown in Table 2 and the temperature difference T1-T2 (° C.) between the heating roller 231 and the pressure roller 232.
[0136]
As shown in Table 2, the comparative example (3) is different from the configurations (1) to (3) in that the pressure roller 232 is heated from the inside by the heater lamp, so that the warm-up time is 424 seconds. Which is extremely long as compared with the configurations (1) to (3).
[0137]
Since the heat capacity of the pressure roller 232 is large and the heat conductivity of the heat-resistant elastic layer 232b made of silicone rubber is poor, the surface of the pressure roller 232 is heated to a predetermined temperature (130 ° C. in this case). However, it takes a very long time.
[0138]
Therefore, as a method of heating the pressure roller 232, an external heating method of heating from the outside by the external heating roller 233 or the like is preferable to an internal heating method using a heater lamp or the like.
[0139]
Furthermore, according to Table 2 and FIG. 3, among those using the external heating method (configurations (1) to (3)), the viewpoint of energy consumption efficiency (power consumption per hour (Wh / h)) Therefore, when the pressure roller 232 is heated so that T1−T2 ≦ 70 (° C.) as in the configuration (2) or (3), the energy consumption efficiency is higher than the configuration (1). Can be reduced.
[0140]
This is because, when T1−T2 ≦ 70 (° C.), the warm-up time (time required for the heating roller to reach the fixing temperature (predetermined predetermined temperature)) can be set to 30 seconds or less. This is because the off mode can be set within 15 minutes or less of the transition time to the low power mode (standby mode). Here, the standby mode time is set to 6 minutes.
[0141]
Here, FIG. 4 shows the heat capacity (J / m ° C.) per unit length (m) in the axial direction of the heating roller 231 and the warm-up time (second) for the constitutions (1) to (3) according to Table 2. FIG.
[0142]
According to the figure, the warm-up time can be reduced to 30 seconds or less by setting the heat capacity per unit length in the axial direction of the heating roller 231 to 200 (J / m ° C.) or less. .
[0143]
By the way, as described above, even if the surface temperature T2 of the pressure roller 232 is set to a high temperature state (that is, T1−T2 ≦ 100 (° C.) or T1−T2 ≦ 70 (° C.)), for example, When the thermal conductivity of the material forming the pressure roller 232 is extremely low, etc., a sufficient amount of heat is not transmitted from the pressure roller 232 to the recording paper P, and the toner T may have a fixing failure.
[0144]
Therefore, the relationship between the heat energy transmitted from the heating roller 231 and the pressure roller 232 to the recording paper P and the required fixing load (N) (the required surface pressure (kPa)) will be discussed below.
[0145]
Here, for the comparative examples (1) to (3) and the constitutions (1) to (3), the heat energy Q1 transmitted from the heating roller 231 to the recording paper P (per sheet) and the recording from the pressure roller 232 are described. The thermal energy Q2 transmitted to the paper (per sheet) P is obtained by a two-dimensional heat transfer simulation. Table 3 shows the thermal energies Q1 and Q2, the ratio of the thermal energies Q1 and Q2, the required fixing load (N), the required surface pressure (kPa), the warm-up time, and the energy consumption efficiency.
[0146]
[Table 3]

[0147]
As shown in Table 3, the ratio (Q2 / (Q1 + Q2)) of the thermal energy Q2 transmitted from the pressure roller 232 to the recording paper P with respect to the total heat amount (total thermal energy) (Q1 + Q2) transmitted to the recording paper P is represented by a heating means. In Comparative Examples (1) and (2), which are not provided, there is only about 22%. Therefore, a very high fixing load (350 kPa or more in surface pressure) was required.
[0148]
On the other hand, in Comparative Example (3) and Configuration Examples (1) to (3), since the heating means for heating the pressure roller 232 is provided, the heat energy Q2 transmitted from the pressure roller 232 to the recording paper P is increased. Is 25% or more. As a result, the required surface pressure becomes 300 kPa or less, and the required fixing load can be reduced.
[0149]
Here, FIG. 5 is a graph showing the relationship between the required surface pressure P (kPa) shown in Table 3 and the ratio Q2 / Q1 + Q2 of the amount of heat Q2 transmitted from the pressure roller 232 to the recording paper P with respect to the total amount of heat Q1 + Q2. .
[0150]
As shown in the figure, the relationship between the required surface pressure P (kPa) and the ratio Q2 / Q1 + Q2 of the heat quantity Q2 to the total heat quantity Q1 + Q2, based on Comparative Examples (1) to (3) and Configurations (1) to (3). Is approximated by the least squares method, it can be approximated as Q2 / Q1 + Q2 = −0.078 × ln (P) +0.7.
[0151]
Further, as described above, considering that a larger value of Q2 / (Q1 + Q2) can reduce a required fixing load because heat energy transmitted from the pressure roller 232 to the recording paper P increases, the required surface pressure P (kPa ) And the ratio Q2 / Q1 + Q2 of the heat quantity Q2 to the total heat quantity Q1 + Q2 is preferably represented by the following equation (2).
[0152]
Q2 / Q1 + Q2 ≧ −0.078 × ln (P) +0.7 (2)
As described above, if the pressure roller 232 is heated and maintained by the external heating roller 233, the ratio of Q2 / Q1 + Q2, that is, the ratio of the heat quantity Q2 transmitted from the pressure roller 232 to the recording paper P can be increased, and the necessary fixing can be performed. The load can be reduced. Accordingly, power consumption can be reduced, and sufficient fixability of the toner T on the recording paper P can be ensured.
[0153]
Next, the warm-up time and the energy consumption efficiency of the configurations (1) to (3) shown in Table 3 are compared with each other with reference to FIG.
[0154]
FIG. 6 is a graph showing the relationship between the warm-up time and energy consumption efficiency shown in Table 3 and the ratio Q2 / Q1 + Q2 of the heat quantity Q2 to the total heat quantity Q1 + Q2.
[0155]
As shown in Table 3 and FIG. 6, in the configuration (2) and (3), Q2 / Q1 + Q2 ≧ 0.313, and the energy consumption efficiency can be further reduced as compared with the configuration (1).
[0156]
This is because when Q2 / (Q1 + Q2) ≧ 0.313 (0.3), the warm-up time is 30 seconds or less, and the off-mode is 15 minutes or less of the transition time to the low power mode (standby mode). This is because setting can be performed. Here, the standby mode time is set to 6 minutes.
[0157]
The shape and material of the rollers 231, 232, 233 are not particularly limited to those described above.
[0158]
Also, the fixing device (heating device) 23 has been described as an example of the device having the configuration including the rollers 231, 232, and 233. However, the present invention is not limited to this. For example, the drying device in a wet electrophotographic image forming apparatus may be used. The present invention can be suitably used for an apparatus, a drying apparatus in an ink jet printer, or an erasing apparatus for rewritable media.
[0159]
Hereinafter, an example in which the above-described fixing device 23 is applied to a dry electrophotographic image forming apparatus will be described with reference to FIGS. 8 to 15.
[0160]
FIG. 8 is a perspective view showing the configuration of the image forming apparatus as viewed from the outside, and FIG. 9 is a diagram showing the internal configuration of the image forming apparatus.
[0161]
As shown in FIGS. 8 and 9, the image forming apparatus includes a document image reading device 11, an image recording device 12, a recording material supply device 13, a post-processing device 14, and an external recording material supply device 15. The fixing device 23 (see FIG. 11) is provided in the image recording device 12, as described later.
[0162]
As shown in FIG. 9, an image recording device 12 as an image forming unit, a recording material supply device 13 as a recording material supply unit, and a recording material from the recording material supply device 13 to the recording material discharge unit 16 via the image recording device 12. An image forming apparatus main body such as a digital printer is configured by the transport unit 17 that transports the (recording paper P). By further providing the document image reading device 11 as an image reading device, a digital copying machine, a facsimile device, and the like can be configured.
[0163]
The operation of the image forming apparatus main body will be described below.
[0164]
First, the document image reading device 11 reads a document to acquire image data, and outputs the image data to the image recording device 12. The image recording device 12 performs appropriate image processing on the input image data.
[0165]
On the other hand, sheet-like recording materials such as printing paper and OHP (Over Head Projector) sheets are separated and carried out one by one from the recording material supply device 13, and the image recording device is transported by the first transport path of the transport unit 17. 12 is conveyed.
[0166]
Then, the image recording device 12 forms an image based on the image data on the recording material by printing or the like. The recording material on which the image is printed is conveyed to the recording material discharge unit 16 by the second conveyance path of the conveyance unit 17 and is discharged outside the apparatus.
[0167]
Further, as shown in FIG. 10, a document tray 18 serving as a document supply unit or a document collection unit is attached to the document image reading device 11.
[0168]
When the document tray 18 functions as a document supply unit, a series of documents including a plurality of pages is placed on the document tray 18. In this case, the document tray 18 can separate the placed documents one by one and supply them continuously to the reading unit.
[0169]
On the other hand, when the document tray 18 functions as a document collection unit, the read document that is continuously discharged is received and held by the document tray 18.
[0170]
For example, when printing a plurality of copies of a series of read originals, if the printed recording material is discharged to the recording material discharge unit 16 shown in FIG. 9, the recording material on which the same page is printed is continuously discharged. Therefore, the user must separate the recording materials after printing.
[0171]
Therefore, for example, the post-processing device 14 can separately discharge the recording material into a plurality of discharge trays so that the recording material does not mix with the main body of the image forming apparatus. Further, the image forming apparatus main body and the post-processing device 14 are installed at a predetermined distance from each other, and a space is formed between the image forming apparatus main body and the post-processing device 14.
[0172]
The image forming apparatus main body and the post-processing device 14 are connected by an external transport unit 19, and the recording material on which the image is printed is transported from the transport unit 17 to the post-processing device 14 via the external transport unit 19. .
[0173]
In addition, from the viewpoint of energy saving and cost reduction, a recording material such as printing paper is required to have a function of printing an image on both surfaces thereof. This function can be realized by the double-sided printing transport unit 21 that reverses the recording material having the image printed on one side thereof and transports the recording material to the image recording apparatus 12 again.
[0174]
The recording material printed on one side is not conveyed to the recording material discharge unit 16 or the post-processing device 14, is turned upside down in the double-sided printing conveyance unit 21, and is conveyed again to the image recording device 12. The image recording device 12 can perform double-sided printing by printing an image on a surface on which no image is printed.
[0175]
Further, when it is desired to supply a recording material exceeding the type or quantity that can be held in the recording material supply device 13, the external recording material supply device 15 is connected to the image forming apparatus main body as a peripheral device for function expansion, and the desired type and quantity are The recording material of the quantity can be supplied by being accommodated in the external recording material supply device 15.
[0176]
Next, each device and parts constituting the image forming apparatus will be described in detail.
[0177]
FIG. 11 is a diagram illustrating a configuration of the image recording device 12. As shown in the figure, an electrophotographic processing section centered on the photosensitive drum 22 is disposed substantially on the left side of the center of the image recording apparatus 12.
[0178]
A charging unit 31 that uniformly charges the surface of the photosensitive drum 22 around the photosensitive drum 22 and a light that scans the uniformly charged photosensitive drum 22 with an optical image to write an electrostatic latent image A scanning unit 24, a developing unit 25 that develops the electrostatic latent image written by the optical scanning unit 24 with a developer, a transfer unit 26 that transfers an image recorded and developed on the surface of the photosensitive drum 22 to a recording material, A cleaning unit 27 and the like that enable the developer remaining on the surface of the photosensitive drum 22 to be removed and a new image to be recorded on the photosensitive drum 22 are sequentially arranged.
[0179]
Above the electrophotographic process unit (image transfer device), a fixing device 23 is disposed, which sequentially receives the recording material on which the image has been transferred by the transfer unit 26 and receives the developer (toner) transferred on the recording material. Heat and fix.
[0180]
The recording material on which the image is printed is discharged from the recording material discharge unit 16 on the upper part of the image recording apparatus 12 with the printing surface facing down (face down). The residual developer removed by the cleaning unit 27 is collected, returned to the developer supply unit 25a of the developing unit 25, and reused.
[0181]
Below the image recording device 12, a recording material supply unit 20 for accommodating a recording material is arranged inside the device. The recording material supply unit 20 separates the recording materials one by one and supplies them to the electrophotographic processing unit.
[0182]
The transport unit 17 includes a plurality of rollers 28 and guides. The recording material is supplied from a recording material supply unit 20 to first rollers defined between rollers, between guides, between the photosensitive drums 22 and the transfer unit 26, and the like. After the image is printed along the transport path, the image is discharged to the recording material discharge unit 16 through a second transport path defined between rollers, between guides, between the fixing units 31, and the like.
[0183]
When the recording material is set in the recording material supply unit 20, the recording material is supplied by pulling out the recording material storage tray in a direction perpendicular to the conveying direction of the image recording apparatus 12, that is, in the front side direction, or the recording material is supplied. Exchange of the etc.
[0184]
The lower surface of the image recording device 12 receives the recording material sent from the recording material supply device 13 (see FIG. 12) of the extension unit, and sequentially supplies the recording material between the photosensitive drum 22 and the transfer unit 26. A recording material receiving section 32 for performing the recording is provided.
[0185]
Further, a process control unit (PCU) board for controlling the electrophotographic process section, an interface board for receiving image data from the outside of the apparatus, an image data received from the interface board, and a document image are provided in the space around the optical scanning unit 24. An image control unit (ICU) substrate for performing predetermined image processing on the image data read by the reading device 11 and scanning and recording as an image by an optical scanning unit, and supplying power to these various substrates and units. A power supply unit and the like for supplying are arranged.
[0186]
The image recording apparatus 12 alone can be connected to an external device such as a personal computer via an interface board and operated as a printer that forms image data from the external device on a recording material.
[0187]
In the above description, the recording material supply unit 20 provided inside the image recording apparatus 12 has been described as one, but the present invention is not limited to this. It is also possible to decorate inside.
[0188]
FIG. 12 is a cross-sectional view illustrating a configuration of the recording material supply device 13 of the extension unit. The recording material supply device 13 can be added as a part of the image recording device 12 when the recording material supply unit 20 alone does not have enough recording material.
[0189]
The recording material supply device 13 can also accommodate a recording material having a size larger than the recording material accommodated in the recording material supply unit 20, and separates the contained recording materials one by one to form a recording material. The sheet is carried out toward the recording material discharge section 33 provided on the upper surface of the supply device 13.
[0190]
In the recording material supply device 13, the tray is composed of three stages of recording material storage trays 34a to 34c, and a recording material storage tray that stores a desired recording material from among the stacked recording material storage trays 34a to 34c is replaced by a PCU. And the like to control and selectively operate to separate and carry out the stored recording material.
[0191]
The transported recording material passes from the recording material discharge unit 33 to the electrophotographic process unit through the recording material receiving unit 32 provided below the image recording apparatus 12. When the recording material is set in the recording material supply device 13, one of the recording material storage trays 34 a to 34 c is pulled out toward the front side of the recording material supply device 13 to supply the recording material or replace the recording material. Is what you do.
[0192]
In the above description, a case is described in which three recording material storage trays 34a to 34c are stacked, but the number of stacked trays can be, for example, at least one, or three or more.
[0193]
A plurality of wheels 35 are provided on the surface of the recording material supply device 13, so that the main body of the image forming apparatus including the recording material supply device 13 can be easily moved at the time of expansion or the like. Further, it is also possible to fix to the installation place by the stopper 36.
[0194]
FIG. 13 is a diagram illustrating a configuration of the external recording material supply device 15. The external recording material supply device 15 is capable of accommodating recording materials exceeding the kind and quantity that can be accommodated in the recording material supply device 13 provided in the image recording device 12, and the recording materials accommodated one by one. After being separated, the sheet is carried out toward the recording material discharge section 37 provided at the upper side of the apparatus.
[0195]
The recording material discharged from the recording material discharge unit 37 is transferred to an external recording material receiving unit 38 (see FIG. 11) provided at a lower part of the side surface of the image recording device 12.
[0196]
When the recording material is set in the external recording material supply device 15, replenishment of the recording material or replacement of the recording material is performed from a supply port 151 shown in FIG. Further, the supply port 151 may be provided with a lid 152 that can be opened and closed, and the supply port may be closed except for replenishment or replacement.
[0197]
As shown in FIG. 13, a plurality of wheels 39 are provided on the lower surface of the external recording material supply device 15, and can be easily moved at the time of expansion or the like. It is also possible to fix to the installation place by a stopper.
[0198]
FIG. 14 is a diagram illustrating a configuration of the post-processing device 14. As shown in FIG. 9, the post-processing device 14 is installed at a predetermined distance from the image forming apparatus main body. The post-processing device 14 and the image forming apparatus main body are connected by an external transport unit 19, and the recording material on which the image is printed by the image forming device main body is transported to the post-processing device 14 via the external transport unit 19. .
[0199]
Note that one end of the external transport unit 19 is connected to the external discharge unit 212 of the image recording device 12, and the other end is connected to the recording material receiving unit 41 of the post-processing device 14.
[0200]
As shown in FIG. 14, the post-processing device 14 has a sort conveyance unit 44 that can selectively discharge the conveyed recording material to the discharge tray 42 or the discharge tray 43. The sort transport section 44 includes a plurality of rollers 45, a guide, and a transport direction switching guide 46. By controlling the transport direction switching guide 46, the tray of the discharge destination can be switched. The user can select one of the discharge trays 42 and 43 as a discharge destination of the recording material, and can discharge the recording material on which the image is printed in a distinguished manner.
[0201]
In addition, as post-processing, in addition to the sorter processing as described above, stapling processing is performed on a predetermined number of recording materials, B4 or A3 size printing paper is folded, or filing is performed on the recording materials. It is also possible to perform post-processing such as drilling.
[0202]
Further, wheels 48 are provided on the lower surface of the post-processing device 14, and can be easily moved.
[0203]
The configuration of the external transport unit 19 is not particularly limited, and the external transport unit 19 may be provided in the post-processing device 14 and the external transport unit 19 and the image recording device 12 may be configured to be detachable. Alternatively, the external transport unit 19, the post-processing device 14, and the image forming apparatus main body 20 may be configured to be detachable.
[0204]
FIG. 10 is a diagram illustrating a configuration of the document image reading device 11. The document image reading device 11 automatically supplies a sheet-shaped document by an automatic document feeder (ADF), sequentially exposes and scans one sheet at a time, and reads an original in an automatic reading mode and a book-shaped document or an ADF. The apparatus can be operated in a manual reading mode in which a sheet-shaped document that cannot be automatically supplied is set by manual operation and the document is read.
[0205]
An image of a document set on a transparent document reading table 49, which is a reading unit, automatically or manually, is exposed and scanned to form an image on a photoelectric conversion element, and is converted into an electrical signal to obtain image data. The acquired image data is output via a connection to the image recording device 12.
[0206]
Further, when reading a double-sided document, it is possible to simultaneously scan and read a document image from both sides of the document in the process of transporting the document along the document transport path.
[0207]
As for reading the lower surface of the document, a moving scanning exposure optical system that scans the lower surface of the document table guides an optical image to the CCD in a state where the optical system stops at a predetermined position on the document transport path and reads the document image. For reading the upper surface of the original, the light source that exposes the original, the optical lens that guides the optical image to the photoelectric conversion element, the photoelectric conversion element that converts the optical image to image data, etc., are integrated. A contact sensor (CIS), which is configured in a typical manner, is arranged.
[0208]
When the reading of the double-sided document is selected, the documents set in the document supply unit 111 are sequentially conveyed, and the images on both sides are read almost simultaneously with the conveyance.
[0209]
A document tray 18 is attached to the document image reading device 11. The document tray 18 is used to supply a document before reading or to receive a read document. When a document is supplied, when the document before reading is placed on the document tray 18, the loading unit of the ADF captures the document and transports the document to the document reading table 49. The read document is discharged out of the apparatus by the document discharge unit. When a document is received, the document is placed on the document supply unit 111 and the loading unit of the ADF captures the document and transports the document to the document reading table 49. The read document is discharged to the document tray 18 by the document discharge unit.
[0210]
FIG. 15 is a diagram illustrating the configuration of the transport device 21 for double-sided printing. The double-sided printing transport device 21 has a double-sided printing transport unit, and is attached to the side surface of the image recording device 12 shown in FIG.
[0211]
The double-sided printing transport unit includes a plurality of rollers 210, and switches back and transports the recording material discharged from the fixing device 23 by using the recording material discharge unit 16 at the upper part of the image recording device. That is, the recording material can be turned over, and the recording material can be supplied again between the photosensitive drum 22 and the transfer device 26 in the electrophotographic process unit of the image recording device 12.
[0212]
In the image forming apparatus 12, the printed recording material is switch-back-conveyed in a conveyance path for discharging the recording material toward the recording material discharge unit 16 in the upper portion of the apparatus, so that the post-processing device 14 shown in FIG. It is possible to guide the recording material to the double-sided printing device 21 shown in FIG.
[0213]
[Embodiment 2]
Another embodiment of the present invention will be described below with reference to FIGS. Note that, in the present embodiment, components having the same functions as the components in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
[0214]
Here, the fixing device in the present embodiment includes an induction heating coil (external heating member) 241 as a heating unit, instead of the external heating roller 233 shown in FIG. 1, as shown in FIG. A drive power supply (not shown) is connected to the induction heating coil 241. In FIG. 7, the cleaning roller is not shown.
[0215]
The pressure roller 232 according to the present embodiment includes a metal core 232a, a heat-resistant elastic material layer 232b made of silicone rubber or the like on the outer peripheral surface of the metal core 232a, a heat generating layer 232d further outside the metal core 232a, and an outermost layer. A release layer 232c is provided to form a four-layer structure.
[0216]
A heat-resistant elastic layer 232b made of foamed silicone rubber and having a thickness of 6 mm is formed on a metal core 232a having a diameter of 28 mm and made of metal such as aluminum, iron or stainless steel.
[0219]
As a material of the core bar 232a, aluminum is more preferable in order to prevent heat generation due to induction heating.
[0218]
The heat generating layer 232d is a heat generating element that generates heat by an induction heating action, and its thickness is reduced to 40 μm to 50 μm in order to shorten the rise time of the surface temperature.
[0219]
The heating layer 232d is heated by induction heating (heating that generates a heating current by electromagnetic induction), and therefore may be made of a material having magnetism and conductivity, such as iron or SUS430 stainless steel. Particularly, a material having a high relative magnetic permeability (for example, 1 or more) is preferable, and a silicon steel sheet, an electromagnetic steel sheet, a nickel steel, or the like may be used.
[0220]
In addition, even if it is a non-magnetic material, it has a high resistance value (for example, 9.8 × 10 ^-6 (Ω · cm or more) If a material can be used for induction heating, it may be used. Further, a non-magnetic base member (for example, a member made of ceramics) may be used as long as the material having a high relative magnetic permeability is arranged to have conductivity. Here, nickel having a thickness of 40 μm manufactured by an electroforming method is used for the heating layer 232d. Further, the heat generating layer 232d may be configured by a layer made of a plurality of materials in order to increase the amount of heat generated.
[0221]
Further, on the surface (outer peripheral surface) of the heat generating layer 232d, PTFE (polytetrafluoroethylene), PFA ( A fluororesin such as a copolymer of tetrafluoroethylene and perfluoroalkylvinylether), or an elastic body such as silicone rubber, fluororubber, or fluorosilicone rubber, or a release layer 232c formed by laminating a plurality of these layers.
[0222]
The pressing roller 232 is pressed against the fixing roller 231 with a force of 274N by a pressing member such as a spring (not shown), thereby forming a fixing nip portion Y having a width of about 7 mm with the fixing roller 231. It is configured to:
[0223]
The heating means for heating the pressure roller 232 includes an induction heating coil 241 as shown in the figure, and is configured to surround the outer circumference of the pressure roller 232. With such a configuration, since there is a curvature, the magnetic flux concentrates on the center side of the induction heating coil 241 and the amount of eddy current generated increases, so that it is convenient to quickly raise the surface temperature of the pressure roller 232. .
[0224]
As the material of the induction heating coil 241, an aluminum single wire (with a surface insulating layer (for example, an oxide film)) is used in consideration of heat resistance, but a copper wire or a copper-based composite member wire is used. It may be a litz wire (a wire obtained by twisting an enamel wire or the like). Regardless of which wire is used, the total resistance of the induction heating coil 241 should be 0.5Ω or less, preferably 0.1Ω or less in order to suppress the Joule loss in the induction heating coil 241. Further, a plurality of induction heating coils 241 may be arranged according to the size of the recording paper P on which the toner T is fixed.
[0225]
The pressure roller 232 is induction-heated by an alternating magnetic field generated by applying a high-frequency current to the induction heating coil 241 from an excitation circuit (not shown).
[0226]
A thermistor (temperature line sensor) 249 as a temperature detecting means is provided on the peripheral surface of the pressure roller 232 so as to detect the surface temperature of the pressure roller 232. Then, based on the detected temperature data, a temperature control unit (control unit) (not shown) controls energization to the induction heating coil 241 so that the temperature of the surface of the pressure roller 232 becomes a predetermined temperature.
[0227]
Here, when the induction heating coil 241 (induction heating method) is used as the heating means of the pressure roller 232 (configuration (4)), the external heating roller 233 (heating roller method) described in the first embodiment is used. Table 4 shows the results of comparison of the heating efficiency (= the amount of heat transmitted to the pressure roller 232 / the power supplied to the power supply) and the average power consumption when the paper is passed (20 sheets) with the case (configuration (2)). Show.
[0228]
[Table 4]

[0229]
As shown in Table 4, in the heating roller method, heat is supplied by heat conduction from the heating roller 231 to the pressure roller 233 using a temperature difference, whereas in the induction heating method, the pressure roller 232 itself is directly heated. In order to generate heat, the induction heating method is superior in heating efficiency to the heating roller method.
[0230]
In addition, in the induction heating method, the induction heating coil 241 itself hardly generates heat, and there is almost no heat loss to the atmosphere as in the heating roller method, so that the average power consumption during paper passing is 37% of that of the heating roller method. In addition, power consumption can be reduced.
[0231]
The present invention is not limited to the embodiments described above, and various modifications are possible within the scope shown in the claims, and are obtained by appropriately combining the technical means disclosed in the different embodiments. Embodiments are also included in the technical scope of the present invention.
[0232]
【The invention's effect】
As described above, the heating device of the present invention includes the external heating member that heats the second heating member from outside the second heating member, and the passage time at which any one point on the material to be heated passes through the pressure contact area. Is 2.3 × 10 ^-2 Second or less, and assuming that the surface temperature of the first heating member is T1 (° C.) and the surface temperature of the second heating member is T2 (° C.), the surface temperatures T1 and T2 are T1−T2 ≦ 100 (° C.). It is a configuration that satisfies.
[0233]
Alternatively, the heating device of the present invention is configured such that the surface temperature T1 of the first heating member and the surface temperature T2 of the second heating member satisfy T1−T2 ≦ 70 (° C.).
[0234]
As a result, the passage time of an arbitrary point on the material to be heated passing through the pressure contact area is 2.3 × 10 3 ^-2 Even with a high-speed machine of less than a second, it is not necessary to increase the surface pressure in the pressure contact area. That is, the load applied to the heating member can be reduced.
[0235]
Therefore, the thickness of the heating member can be reduced, and the heat capacity can be reduced. Thereby, the warm-up time of the heating device can be reduced. As a result, it is not necessary to preheat the heating member, and it is possible to reduce power consumption during warm-up and standby.
[0236]
Further, since the load applied to the heating member is small, it is possible to prevent, for example, generation of creep and shortening of the life of the heating member.
[0237]
Further, since the thickness of the heating member can be reduced, the size of the heating device can be reduced. In addition, since the driving torque of the heating member can be reduced, power consumption can be reduced, and the life of the driving component can be prevented from being shortened.
[0238]
The heating device of the present invention has a configuration in which the difference between the surface temperature of the first heating member and the surface temperature of the second heating member is controlled by an external heating member.
[0239]
Specifically, the heating device of the present invention includes a temperature detecting unit that detects a surface temperature of the external heating member, and a control unit that controls the surface temperature of the external heating member based on a detection result of the temperature detecting unit. It is a configuration provided.
[0240]
Thereby, since the external heating member heats the second heating member from outside the second heating member, the surface temperature of the second heating member can be easily controlled.
[0241]
Therefore, there is an effect that the difference between the surface temperature of the first heating member and the surface temperature of the second heating member can be controlled with a simple configuration.
[0242]
The heating device of the present invention is configured so that the surface temperature of the first heating member is controlled to be kept substantially constant.
[0243]
As a result, the surface temperature of the first heating member is kept substantially constant, and the difference between the surface temperature of the first heating member and the surface temperature of the second heating member is determined by the external heating member. There is an effect that the control can be performed only by the control.
[0244]
In the heating device of the present invention, assuming that the surface pressure on the material to be heated in the pressure contact region is P (kPa), the surface temperature T1 (° C.) of the first heating member and the surface temperature T2 (° C.) of the second heating member are obtained. Is a configuration satisfying T1−T2 ≦ 30 × ln (P) −72.5.
[0245]
Thereby, T1-T2 can be reduced, and the amount of heat transmitted to the material to be heated can be increased. Therefore, there is an effect that the load applied to the heating member can be reduced.
[0246]
As described above, according to the heating device of the present invention, the passage time for an arbitrary point on the material to be heated to pass through the pressure contact area is 2.3 × 10 ^-2 Second or less, and when the material to be heated passes, the amount of heat transmitted from the first heating member to the material to be heated is Q1, and the amount of heat transmitted from the second heating member to the material to be heated is Q2. Q2 is a configuration that satisfies Q2 / (Q1 + Q2) ≧ 0.25.
[0247]
Alternatively, the heating device of the present invention is configured such that the amounts of heat Q1 and Q2 satisfy Q2 / (Q1 + Q2) ≧ 0.3.
[0248]
Accordingly, the surface temperature T1 of the first heating member and the surface temperature T2 of the second heating member described above satisfy T1−T2 ≦ 70 (° C.) regardless of the material of the heating member. The same effect as in the case defined in (1) can be obtained.
[0249]
That is, it is possible to reduce the load applied to the heating member and to reduce power consumption.
[0250]
The heating device of the present invention transmits the second heating member from the second heating member to the material to be heated by controlling the surface temperature of the external heating member and the external heating member for heating the second heating member from outside the second heating member. And a control means for controlling the ratio Q2 / (Q1 + Q2) of the heat quantity Q2 to be transmitted and the total heat quantity Q1 + Q2 transmitted to the material to be heated.
[0251]
Thereby, Q2 / (Q1 + Q2) can be controlled by the external heating member. Therefore, there is an effect that Q2 / (Q1 + Q2) can be controlled with a simple configuration.
[0252]
In the heating device of the present invention, when the surface pressure on the material to be heated in the pressure contact region is P (kPa), the amount of heat Q2 (J) transmitted from the second heating member to the material to be heated and the amount of heat Q2 (J) transmitted to the material to be heated. The ratio Q2 / (Q1 + Q2) to the total amount of heat Q1 + Q2 (J) satisfies Q2 / (Q1 + Q2) ≧ −0.078 × ln (P) +0.7.
[0253]
Thus, the ratio of the heat amount Q2 transmitted from the second heating member to the material to be heated can be increased, and the required fixing load can be reduced. Therefore, there is an effect that power consumption can be reduced.
[0254]
The heating device of the present invention has a configuration in which the surface pressure on the material to be heated in the pressure contact region is 300 (kPa) or less.
[0255]
Thereby, there is an effect that the load applied to the heating member and the material to be heated can be reduced.
[0256]
The heating device of the present invention has a configuration in which the external heating member has a heat source body and heats the second heating member by being in contact with the surface of the second heating member.
[0257]
Thereby, since the surface of the second heating member can be directly heated, the configuration of the external heating member can be simplified, and the space can be saved. Therefore, for example, there is an effect that installation of other components such as a cleaning roller can be facilitated.
[0258]
The heating device of the present invention has a configuration in which the external heating member is a roller that is circumscribed with the second heating member and rotates together with the second heating member.
[0259]
Thereby, the second heating member can be heated with a simple configuration. Therefore, it is possible to save space, and it is possible to easily install other components such as a cleaning member.
[0260]
The heating device of the present invention has a configuration in which the second heating member includes a heating element that generates heat by induction heating, and the external heating member is an induction heating coil that induction-heats the second heating member.
[0261]
This allows the second heating member to directly generate heat, thereby reducing heat loss due to radiation and convection from the surface of the second heating member. Further, since the external heating member itself hardly generates heat, heat loss of the external heating member itself is small. Therefore, there is an effect that the thermal efficiency can be further improved.
[0262]
The heating device of the present invention has a configuration in which the shape of the external heating member has a curvature.
[0263]
Thereby, magnetic flux concentrates on the center side of the induction heating coil as the external heating member, and the amount of eddy current generated increases. Therefore, there is an effect that the rise of heat generation of the second heating member can be made faster.
[0264]
The heating device of the present invention has a configuration in which the surface of the first heating member has a heat capacity per unit length of 200 J / (m · ° C.) or less.
[0265]
As a result, for example, the warm-up time can be reduced to 30 seconds or less, and the power consumption during standby can be significantly reduced.
[0266]
The heating device of the present invention is configured such that the first heating member and the second heating member are rotatable rollers, and are configured to fix the toner on the heated material by passing the heated material through the pressure contact area.
[0267]
Thus, the heating device can be used as a fixing device. Therefore, the power consumption can be reduced due to the small load while securing the fixing property of the toner, and wrinkles and curling of the recording paper (recording medium) as the material to be heated can be prevented. Play.
[0268]
As described above, the image forming apparatus of the present invention includes an image transfer device that forms an image made of unfixed toner on a material to be heated and a heating device that fixes unfixed toner on a material to be heated. It is a configuration provided with:
[0269]
Thus, an image forming apparatus with low power consumption can be provided. Further, for example, a heating device can be used as a fixing device. Therefore, the power consumption can be reduced due to the small load while securing the fixing property of the toner, and wrinkles and curls can be prevented from occurring on the recording paper (recording medium) as the material to be heated.
[0270]
Further, there is an effect that an image forming apparatus using a heating device capable of extending the life of the heating member and the driving components can be provided.
[0271]
As described above, according to the heating method of the present invention, any one point of the material to be heated is set to 2.3 × 10 ^-2 A heating method for heating the material to be heated by passing the material to be heated so as to pass within seconds, wherein the surface temperature of the first heating member is T1 (° C.), and the second heating member is When the surface temperature of the second heating member is T2 (° C.), the second heating member is externally heated from outside the second heating member so that the surface temperature T1 · T2 satisfies T1−T2 ≦ 100 (° C.). This is a configuration in which heating is performed by a member.
[0272]
Alternatively, the heating method of the present invention includes the step of: heating the second heating member so that the surface temperatures T1 and T2 of the first and second heating members satisfy T1−T2 ≦ 70 (° C.). In this configuration, heating is performed by an external heating member from the outside.
[0273]
As a result, the passage time of an arbitrary point on the material to be heated passing through the pressure contact area is 2.3 × 10 3 ^-2 Even with a high-speed machine of less than a second, it is not necessary to increase the surface pressure in the pressure contact area. That is, the load applied to the heating member can be reduced.
[0274]
Therefore, the thickness of the heating member can be reduced, and the heat capacity can be reduced. Thereby, the warm-up time of the heating device using the above-described heating method can be reduced. As a result, it is not necessary to preheat the heating member, and the effect of reducing power consumption during warm-up and standby can be achieved.
[0275]
The heating method of the present invention is configured to control the difference between the surface temperature of the first heating member and the surface temperature of the second heating member by controlling the surface temperature of the external heating member.
[0276]
Thereby, there is an effect that the difference between the surface temperature of the first heating member and the surface temperature of the second heating member can be controlled with a simple configuration.
[0277]
In the heating method of the present invention, assuming that the surface pressure on the material to be heated in the pressure contact region is P (kPa), the surface temperature T1 (° C.) of the first heating member and the surface temperature T2 (° C.) of the second heating member are: , T1−T2 ≦ 30 × ln (P) −72.5, and controls the surface temperatures T1 and T2.
[0278]
Thereby, there is an effect that the load applied to the heating member can be reduced.
[0279]
As described above, according to the heating method of the present invention, any one point of the material to be heated is set to 2.3 × 10 ^-2 A heating method for heating the material to be heated by passing the material to be heated so that the material to be heated is passed within seconds. Assuming that the amount of heat transmitted to the heating material is Q1, and the amount of heat transmitted from the second heating member to the material to be heated is Q2, the amount of heat Q1 · Q2 satisfies Q2 / (Q1 + Q2) ≧ 0.25. The configuration is such that control is performed as follows.
[0280]
Alternatively, the heating method of the present invention is configured so that the heat amounts Q1 and Q2 are controlled so as to satisfy Q2 / (Q1 + Q2) ≧ 0.3.
[0281]
With this, not the temperature of the heating member but the amount of heat transmitted to the material to be heated is specified. Therefore, regardless of what kind of material the heating member is made of, the surface temperature T1 of the first heating member described above. The same effect as in the case where the surface temperature T2 of the second heating member is defined to satisfy T1−T2 ≦ 70 (° C.) can be obtained. That is, it is possible to reduce the load applied to the heating member and to reduce power consumption.
[0282]
The heating method of the present invention controls the surface temperature of the second heating member by an external heating member that heats the second heating member from the outside, so that the amount of heat Q2 transmitted from the second heating member to the material to be heated, In this configuration, the ratio Q2 / (Q1 + Q2) to the total amount of heat Q1 + Q2 transmitted to the heating material is controlled.
[0283]
Thereby, Q2 / (Q1 + Q2) can be controlled by the external heating member. Therefore, there is an effect that Q2 / (Q1 + Q2) can be controlled with a simple configuration.
[0284]
In the heating method of the present invention, assuming that the surface pressure on the material to be heated in the pressure contact region is P (kPa), the amount of heat Q2 (J) transmitted from the second heating member to the material to be heated is the same as that of the material to be heated. The ratio Q2 / (Q1 + Q2) to the total amount of heat Q1 + Q2 (J) transmitted to the material is controlled so as to satisfy Q2 / (Q1 + Q2) ≧ −0.078 × ln (P) +0.7. It is.
[0285]
Thus, the ratio of the heat amount Q2 transmitted from the second heating member to the material to be heated can be increased, and the required fixing load can be reduced. Therefore, there is an effect that power consumption can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a main part of a fixing device according to an embodiment of the present invention.
FIG. 2 is a graph showing a relationship between a required surface pressure (kPa) and a temperature difference (° C.) between a surface temperature T1 of a heating roller and a surface temperature T2 of a pressure roller.
FIG. 3 is a graph showing a relationship between a warm-up time (second) and energy consumption efficiency (Wh / h), and a temperature difference (° C.) between a surface temperature T1 of a heating roller and a surface temperature T2 of a pressure roller.
FIG. 4 is a graph showing the relationship between the heat capacity per unit length in the axial direction of the heating roller (J / m ° C.) and the warm-up time (second).
FIG. 5 is a graph showing a relationship between a required surface pressure P (kPa) and a ratio Q2 / Q1 + Q2 of a thermal energy Q2 transmitted from a pressure roller to a recording sheet P with respect to a total heat amount Q1 + Q2.
FIG. 6 is a graph showing a relationship between a warm-up time and energy consumption efficiency, and a ratio Q2 / Q1 + Q2 of a heat quantity Q2 to a total heat quantity Q1 + Q2.
FIG. 7 is a diagram showing a configuration of a main part of a fixing device according to another embodiment of the present invention.
FIG. 8 is a perspective view illustrating a configuration of an image forming apparatus including the fixing device illustrated in FIG. 1 when viewed from the outside.
FIG. 9 is a diagram illustrating an internal configuration of the image forming apparatus.
FIG. 10 is a diagram illustrating a configuration of a document image reading device in the image forming apparatus.
FIG. 11 is a diagram illustrating a configuration of an image recording apparatus in the image forming apparatus.
FIG. 12 is a diagram illustrating a configuration of a recording material supply device in the image forming apparatus.
FIG. 13 is a diagram illustrating a configuration of an external recording material supply device in the image forming apparatus.
FIG. 14 is a diagram illustrating a configuration of a post-processing device in the image forming apparatus.
FIG. 15 is a diagram illustrating a configuration of a conveyance unit for double-sided printing in the image forming apparatus.
FIG. 16 is a graph showing a relationship between a nip passage time in a conventional medium-speed machine and a high-speed machine, a roller temperature, and a surface pressure applied to a recording sheet passing through a fixing nip portion.
[Explanation of symbols]
23 Fixing device
231 heating roller (first heating member)
232 pressure roller (second heating member)
232d Heating layer (heating element)
233 External heating roller (external heating member)
234, 235, 239 Heater lamp (heat source)
236, 237, 242, 249 Temperature sensor (temperature detecting means)
240 cleaning roller
241 Induction heating coil (external heating member)
Y Fixing nip (pressure contact area)
P Recording paper (material to be heated, recording medium)
T toner

Claims (26)

A first heating member and a second heating member that are in pressure contact with each other are provided, and the material to be heated is heated by the material to be heated passing through a pressure contact region where the first heating member and the second heating member are in pressure contact with each other. In the heating device,
An external heating member that heats the second heating member from outside the second heating member,
The time required for any one point on the material to be heated to pass through the pressure contact area is 2.3 × 10 ⁻² seconds or less,
Assuming that the surface temperature of the first heating member is T1 (° C.) and the surface temperature of the second heating member is T2 (° C.), the surface temperature T1 and the surface temperature T2 are:
T1-T2 ≦ 100 (° C.)
A heating device characterized by satisfying the following. The surface temperature T1 of the first heating member and the surface temperature T2 of the second heating member are:
T1-T2 ≦ 70 (° C.)
The heating device according to claim 1, wherein the following conditions are satisfied. The heating device according to claim 1, wherein a difference between a surface temperature of the first heating member and a surface temperature of the second heating member is controlled by the external heating member. The heating device according to claim 3, wherein the surface temperature of the first heating member is controlled to be kept substantially constant. Temperature detection means for detecting the surface temperature of the external heating member,
The heating device according to claim 3, further comprising control means for controlling a surface temperature of the external heating member based on a detection result of the temperature detection means. Assuming that the surface pressure on the material to be heated in the pressure contact region is P (kPa), the surface temperature T1 (° C.) of the first heating member and the surface temperature T2 (° C.) of the second heating member are:
T1−T2 ≦ 30 × ln (P) −72.5
The heating device according to claim 1, wherein the following conditions are satisfied. A first heating member and a second heating member that are in pressure contact with each other are provided, and the material to be heated is heated by the material to be heated passing through a pressure contact region where the first heating member and the second heating member are in pressure contact with each other. In the heating device,
The time required for any one point on the material to be heated to pass through the pressure contact area is 2.3 × 10 ⁻² seconds or less,
When the amount of heat transmitted from the first heating member to the material to be heated when passing through the material to be heated is Q1, and the amount of heat transmitted to the material to be heated from the second heating member is Q2, the amount of heat Q1 And the heat quantity Q2 is
Q2 / (Q1 + Q2) ≧ 0.25
A heating device characterized by satisfying the following. The amount of heat Q1 transmitted from the first heating member to the material to be heated and the amount of heat Q2 transmitted from the second heating member to the material to be heated are:
Q2 / (Q1 + Q2) ≧ 0.3
The heating device according to claim 7, wherein An external heating member that heats the second heating member from outside the second heating member,
By controlling the surface temperature of the external heating member, the ratio Q2 / (Q1 + Q2) of the amount of heat Q2 transmitted from the second heating member to the material to be heated and the total amount of heat Q1 + Q2 transmitted to the material to be heated. The heating device according to claim 7, further comprising control means for controlling the temperature of the heating device. Assuming that the surface pressure on the material to be heated in the pressure contact region is P (kPa), the amount of heat Q2 (J) transmitted from the second heating member to the material to be heated and the total amount of heat transmitted to the material to be heated. The ratio Q2 / (Q1 + Q2) to the calorific value Q1 + Q2 (J) is
Q2 / (Q1 + Q2) ≧ −0.078 × ln (P) +0.7
The heating device according to claim 7, wherein The heating device according to claim 1, wherein a surface pressure on the material to be heated in the pressure contact region is 300 (kPa) or less. The heating device according to claim 1, wherein the external heating member has a heat source body, and heats the second heating member by being in contact with a surface of the second heating member. The heating device according to claim 1, wherein the external heating member is a roller that circumscribes the second heating member and rotates together with the second heating member. The second heating member includes a heating element that generates heat by an induction heating action,
The said external heating member is an induction heating coil which induction-heats the said 2nd heating member, The heating apparatus of Claim 1 or 7 characterized by the above-mentioned. The heating device according to claim 14, wherein the shape of the external heating member has a curvature. The heating device according to claim 1, wherein the surface of the first heating member has a heat capacity per unit length of 200 J / (m · ° C.) or less. 2. The method according to claim 1, wherein the first heating member and the second heating member are rotatable rollers, and fix the toner on the heated material by passing the heated material through a pressure contact area. 8. The heating device according to 7. An image transfer device that forms an image composed of unfixed toner on the material to be heated,
An image forming apparatus comprising: the heating device according to any one of claims 1 to 17 for fixing unfixed toner on the material to be heated. By passing the above-mentioned heated material so that an arbitrary point of the heated material passes within a pressure contact area where the first heating member and the second heating member are pressed against each other within 2.3 × 10 ⁻² seconds, A heating method for heating a material to be heated,
If the surface temperature of the first heating member is T1 (° C.) and the surface temperature of the second heating member is T2 (° C.), the surface temperature T1 and the surface temperature T2 are:
T1-T2 ≦ 100 (° C.)
A heating method, wherein the second heating member is heated by an external heating member from outside the second heating member so as to satisfy the following. The surface temperature T1 of the first heating member and the surface temperature T2 of the second heating member are:
T1-T2 ≦ 70 (° C.)
20. The heating method according to claim 19, wherein the second heating member is heated by an external heating member from outside the second heating member so as to satisfy the following. The heating method according to claim 19, wherein a difference between a surface temperature of the first heating member and a surface temperature of the second heating member is controlled by controlling a surface temperature of the external heating member. Assuming that the surface pressure on the material to be heated in the pressure contact region is P (kPa), the surface temperature T1 (° C.) of the first heating member and the surface temperature T2 (° C.) of the second heating member are:
T1−T2 ≦ 30 × ln (P) −72.5
20. The heating method according to claim 19, wherein the surface temperature T1 and the display temperature T2 are controlled so as to satisfy the following. By passing the above-mentioned heated material so that an arbitrary point of the heated material passes within a pressure contact area where the first heating member and the second heating member are pressed against each other within 2.3 × 10 ⁻² seconds, A heating method for heating a material to be heated,
When the amount of heat transmitted from the first heating member to the material to be heated when passing through the material to be heated in the pressure contact region is Q1, the amount of heat transmitted to the material to be heated from the second heating member is Q2. , The heat quantity Q1 and the heat quantity Q2,
Q2 / (Q1 + Q2) ≧ 0.25
A heating method characterized by controlling so as to satisfy the following. The amount of heat Q1 transmitted from the first heating member to the material to be heated and the amount of heat Q2 transmitted from the second heating member to the material to be heated are:
Q2 / (Q1 + Q2) ≧ 0.3
The heating method according to claim 23, wherein the heating is controlled so as to satisfy the following condition. By controlling the surface temperature of the second heating member with an external heating member that heats the second heating member from the outside, the amount of heat Q2 transmitted from the second heating member to the material to be heated, 24. The heating method according to claim 23, wherein a ratio Q2 / (Q1 + Q2) with respect to a total amount of heat Q1 + Q2 transmitted to the heater is controlled. Assuming that the surface pressure on the material to be heated in the pressure contact region is P (kPa), the amount of heat Q2 (J) transmitted from the second heating member to the material to be heated and the total amount of heat transmitted to the material to be heated are The ratio Q2 / (Q1 + Q2) to the calorific value Q1 + Q2 (J) is
Q2 / (Q1 + Q2) ≧ −0.078 × ln (P) +0.7
The heating method according to claim 23, wherein the heating is controlled so as to satisfy the following.

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