JP2004279661A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safe fixing device for preventing smoking, ignition, or the like. <P>SOLUTION: The fixing device comprises a drive operation detection means 350 for detecting that a drive means 360 for rotating or moving a heating roller 130 and a heat-resistant belt 150 is operated normally; a heat generation member rotation movement detection means 340 for detecting that the heating roller 130 and the heat-resistant belt 150 are rotated or moved normally; an invertor circuit 310; and a control circuit 320 for controlling the invertor circuit 310. When abnormality is detected by the drive operation detection means 350 or the heat generation member rotation movement detection means 340, the control circuit 320 stops or restricts the output of the invertor circuit 310, thus preventing the smoking, ignition, or the like, in advance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００８６】
【表２】

【００８７】
【表３】

【００８８】
【表４】

【００８９】
【表５】

【００９０】
【表６】

【００９１】
まず、ＣＰＵ３７０は発熱部材検知手段からの信号ＦＳＲが「１」であることを確認し、モード設定レジスタ３２３に「２」を書込む（信号ＭＯＤは「２」となる）。信号ＦＳＲが「０」の場合、印字動作は行なわない。次に、ＣＰＵ３７０は駆動手段３６０への信号ＭＯＮを「１」にすることで駆動手段３６０は回転駆動を開始する。所定時間Ｔ１に駆動手段３６０が所定の回転数になると駆動動作検知手段３５０は信号ＬＤを「１」にし、所定時間Ｔ２後に加熱ローラ１３０および耐熱性ベルト１５０が正常に回転すると、回転移動検知手段３４０は信号ＲＯＴを「１」にする。ＣＰＵは信号ＬＤと信号ＲＯＴのどちらも「１」であることを確認し、信号ＩＨＯＮを「１」にするとともにパワー設定レジスタ３２４に所定のデータ（ここでは「８０Ｈ」）を書き込む。
【００９２】
制御回路３２０内のイネーブル生成回路３２１は信号ＭＯＤ＝２（印字時）の場合、（表３）に示すように信号ＦＳＲ、信号ＬＤ、信号ＲＯＴが全て「１」の時、信号ＩＨＯＮと同じ状態を信号ＩＨＥＮＢに出力する。また、パルス生成回路３２２は信号ＭＯＤ＝２（印字時）の場合、（表６）に示すように信号ＬＤ、信号ＲＯＴが全て「１」の時、パワー設定レジスタ３２４に設定されているデータである信号ＰＷ分のパルスを信号ＩＨＰＯＷＥＲに出力する。この場合、パワー設定レジスタ３２４には「８０Ｈ」が設定されているので信号ＩＨＰＯＷＥＲはデューティ５０％のパルスとなる。
【００９３】
インバータ回路３１０は信号ＩＨＥＮＢがイネーブル状態であるので、信号ＩＨＰＯＷＥＲのデューティに従ったパワーを出力する。この場合、信号ＩＨＰＯＷＥＲのデューティ５０％であるので約５００Ｗのパワーが出力され、加熱ローラ１３０および耐熱性ベルト１５０が加熱される。
【００９４】
定着された最終のシート材９０が排紙トレイ（図示せず）へ搬送されるとＣＰＵ３７０は信号ＩＨＯＮを「０」にするとともにパワー設定レジスタ３２４へ「００Ｈ」を書き込み、その後信号ＭＯＮを「０」にし駆動手段３６０を停止させ、定着動作が終了する。
【００９５】
ここでＣＰＵ３７０は信号ＦＳＲが「１」であることを確認してからインバータ回路３１０の出力をイネーブルにすること、また印字加熱中（ＭＯＤ＝２）において、何らかの原因で信号ＦＳＲが「０」になると異常が発生したと認識し、信号ＩＨＯＮを「０」にするとともにパワー設定レジスタ３２４へ「００Ｈ」を書き込み、加熱を停止させることにより、定着装置１２０が正常に装着されていなければインバータ回路の出力を停止させ不要な電磁波の漏洩を防ぐことができる。
【００９６】
また印字加熱中（ＭＯＤ＝２）において、何らかの原因で信号ＬＤまたは信号ＲＯＴの何れかが「０」になると異常が発生したと認識し、信号ＩＨＯＮを「０」にするとともにパワー設定レジスタ３２４へ「００Ｈ」を書き込み、加熱を停止させることにより、加熱ローラ１３０および耐熱性ベルト１５０が局所的に加熱されることがなくなり、発煙や発火を未然に防ぐことできる。
【００９７】
上述の異常が発生した時には、制御回路３２０は（表３）および（表６）に示すようにＣＰＵ３７０と同様に加熱を停止させる。つまり上述の異常が発生した場合は、ソフトウェアを介さずに加熱を停止させるため、異常時に何らかの原因でＣＰＵ３７０が加熱を停止させない状態においても、確実に加熱を停止させることができる。
【００９８】
次に図７、（表１）〜（表６）を用いて加熱を行なう待機時の定着装置の動作について説明する。
【００９９】
まず、ＣＰＵ３７０は発熱部材検知手段からの信号ＦＳＲが「１」であることを確認し、モード設定レジスタ３２３に「１」を書込む（信号ＭＯＤは「１」となる）。次に、信号ＩＨＯＮを「１」にするとともにパワー設定レジスタ３２４に所定のデータ（ここでは「４０Ｈ」）を書き込む。この待機状態での加熱は、定着装置を１００℃程度に保温するための加熱であり、低いパワーが設定される。
【０１００】
制御回路３２０内のイネーブル生成回路３２１は信号ＭＯＤ＝１（加熱を行なう待機状態）の場合、（表２）に示すように信号ＦＳＲが「１」の時、信号ＩＨＯＮと同じ状態を信号ＩＨＥＮＢに出力する。また、パルス生成回路３２２は信号ＭＯＤ＝１（加熱を行なう待機状態）の場合、（表５）に示すように信号ＬＤ、信号ＲＯＴの状態に無関係にパワー設定レジスタ３２４に設定されているデータである信号ＰＷ分のパルスを信号ＩＨＰＯＷＥＲに出力する。ただし、信号ＰＷが信号ＥＰＷより大きな値に設定されても、信号ＩＨＰＯＷＥＲは信号ＥＰＷより大きな値にはならない。ここでは、信号ＥＰＷは「５０Ｈ」が固定値として設定されている。また、パワー設定レジスタ３２４には「４０Ｈ」が設定されているので信号ＩＨＰＯＷＥＲはデューティ２５％のパルスとなる。
【０１０１】
インバータ回路３１０は信号ＩＨＥＮＢがイネーブル状態であるので、信号ＩＨＰＯＷＥＲのデューティに従ったパワーを出力する。この場合、信号ＩＨＰＯＷＥＲのデューティ２５％であるので約２５０Ｗのパワーが出力され、加熱ローラ１３０および耐熱性ベルト１５０が加熱される。
【０１０２】
ここで、何らかの原因でＣＰＵ３７０がパワー設定レジスタ３２４に大きな値（例えば「ＦＦＨ」）を設定したとしても、制御回路３２０は信号ＥＰＷより大きな値のパルスを信号ＩＨＰＯＷＥＲに出力することがないので、加熱ローラ１３０および耐熱性ベルト１５０が回転していない状態において大きなパワーで加熱されることがなく、発煙や発火を未然に防ぐことできる。
【０１０３】
次に本発明の第二の実施の形態について、図８、図９、（表７）〜（表１２）を用いて説明する。
【０１０４】
図８は本発明の第二の実施の形態である電磁誘導加熱方式による定着装置の制御回路およびその周辺回路を示すブロック図である。図９は図８の電磁誘導加熱方式による印字時の動作を示すタイミングチャートである。（表７）〜（表９）は本発明の第二の実施の形態である電磁誘導加熱方式におけるイネーブル生成回路の入力と出力の関係を示す表である。（表１０）〜（表１２）は本発明の第二の実施の形態である電磁誘導加熱方式におけるパルス生成回路の入力と出力の関係を示す表である。
【０１０５】
【表７】

【０１０６】
【表８】

【０１０７】
【表９】

【０１０８】
【表１０】

【０１０９】
【表１１】

【０１１０】
【表１２】

【０１１１】
図９においてＣＰＵ監視回路３２６は信号ＴＧＬの状態をモニターし、信号ＴＧＬの状態が所定の時間Ｔ３内に「０」から「１」または「１」から「０」へ変化すると信号ＷＤに「１」を出力し、Ｔ３以内に変化がない場合は「０」を出力する。
【０１１２】
イネーブル生成回路３２１は（表７）〜（表９）に示すように、信号ＷＤが「１」の時のみ第一の実施例の表１のように信号ＩＨＯＮを出力する。信号ＷＤが「０」の時は信号ＩＨＯＮに常に「０」を出力する。
【０１１３】
パルス生成回路３２２は表４に示すように、信号ＷＤが「１」の時のみ第一の実施例の表２のように信号ＩＨＰＯＷＥＲを出力する。信号ＷＤが「０」の時は信号ＩＨＰＯＷＥＲに常に「０」を出力する。
【０１１４】
ここで印字時の定着装置の動作について説明する。
【０１１５】
まず、ＣＰＵ３７０は発熱部材検知手段からの信号ＦＳＲが「１」であることを確認し、モード設定レジスタ３２３に「２」を書込むとともに信号ＴＧＬを現在の状態と違う状態にする。ここでは信号ＴＧＬを「０」から「１」にし、その後、時間Ｔ４毎に状態を変化させ続ける。ＣＰＵ監視回路３２６は所定の時間Ｔ３以内に信号ＴＧＬの状態が変化した時点で信号ＷＤに「１」を出力する（時間Ｔ４とＴ３はＴ４＞Ｔ３の関係にある）。
【０１１６】
次に、ＣＰＵ３７０は駆動手段３６０への信号ＭＯＮを「１」にすることで駆動手段３６０は回転駆動を開始する。所定時間Ｔ１に駆動手段３６０が所定の回転数になると駆動動作検知手段３５０は信号ＬＤを「１」にし、所定時間Ｔ２後に加熱ローラ１３０および耐熱性ベルト１５０が正常に回転すると、回転移動検知手段３４０は信号ＲＯＴを「１」にする。ＣＰＵは信号ＬＤと信号ＲＯＴのどちらも「１」であることを確認し、信号ＩＨＯＮを「１」にするとともにパワー設定レジスタ３２４に所定のデータ（ここでは「８０Ｈ」）を書き込む。
【０１１７】
制御回路３２０内のイネーブル生成回路３２１は信号ＭＯＤ＝２（印字時）の場合、（表９）に示すように信号ＷＤ、信号ＦＳＲ、信号ＬＤ、信号ＲＯＴが全て「１」の時、信号ＩＨＯＮと同じ状態を信号ＩＨＥＮＢに出力する。また、パルス生成回路３２２は信号ＭＯＤ＝２（印字時）の場合、（表１２）に示すように信号ＷＤ、信号ＬＤ、信号ＲＯＴが全て「１」の時、パワー設定レジスタ３２４に設定されているデータである信号ＰＷ分のパルスを信号ＩＨＰＯＷＥＲに出力する。ここではパワー設定レジスタ３２４には「８０Ｈ」が設定されているので信号ＩＨＰＯＷＥＲはデューティ５０％のパルスとなる。
【０１１８】
インバータ回路３１０は信号ＩＨＥＮＢがイネーブル状態であるので、信号ＩＨＰＯＷＥＲのデューティに従ったパワーを出力する。この場合、信号ＩＨＰＯＷＥＲのデューティ５０％であるので約５００Ｗのパワーが出力され、加熱ローラ１３０および耐熱性ベルト１５０が加熱される。
【０１１９】
定着された最終のシート材９０が排紙トレイ（図示せず）へ搬送されるとＣＰＵ３７０は信号ＩＨＯＮを「０」にするとともにパワー設定レジスタ３２４へ「００Ｈ」を書き込む。その後信号ＴＧＬの状態を変化させることを止め、ＣＰＵ監視回路３２６は信号ＴＧＬの状態変化がＴ３以内に行なわれなくなった時点で信号ＷＤに「０」を出力する。さらにＣＰＵ３７０は信号ＭＯＮを「０」にし駆動手段３６０を停止させ、定着動作が終了する。
【０１２０】
ここでＣＰＵ監視回路３２６は常に信号ＴＧＬをモニターしているので、ＣＰＵ３７０が何らかの原因で印字加熱中に暴走したとしても、その暴走を未然に認識し、信号ＩＨＥＮＢと信号ＩＨＰＯＷＥＲは「０」になり、加熱を停止させることで発煙や発火を未然に防ぐことできる。
【０１２１】
次に本発明の第三の実施の形態について、図１０を用いて説明する。
【０１２２】
図１０は本発明の第三の実施の形態である電磁誘導加熱方式による定着装置のインバータ回路と制御回路の接続を示すブロック図である。
【０１２３】
スイッチ４００は定着器交換時に使われるドア（図示せず）の開閉に連動したスイッチである。制御回路３２０からの出力信号ＩＨＥＮＢはスイッチ４００を介してインバータ回路３１０に接続され、前述のドア（図示せず）が開いた状態（定着器交換時）の時は「Ｈｉ−Ｚ」となり、インバータ回路は出力停止状態となる。通常の印字状態では前述のドアは閉められた状態であり、信号ＩＨＥＮＢはそのまま状態でインバータ回路へ伝達される。
【０１２４】
このように制御回路３２０とインバータ回路３１０との接続を、定着器交換時のドアに連動したスイッチを介して行ない、スイッチがオープン状態（ドア開）の時は、インバータ回路の出力を停止することでユーザーが安全に定着器の交換をすることが可能である。
【０１２５】
【発明の効果】
以上のように、本発明によれば発熱部材を駆動する駆動手段が正常に動作していることを検知する駆動動作検知手段と発熱部材が正常に回転、移動していることを検知する発熱部材回転移動検知手段を設け、どちらかの検知結果が異常の場合はインバータ回路の出力を停止または制限することで、発煙や発火等を防止できるという有効な効果が得られる。
【０１２６】
また、定着器（発熱部材）が正常に装着されていることを検知する発熱部材検知手段を設け、正常に装着されていなければインバータ回路の出力を停止することで、不要な電磁波の漏洩を防ぐことができるという有効な効果が得られる。
【０１２７】
また、制御回路が駆動動作検知手段と発熱部材回転移動検知手段のどちらかの検知結果が異常の場合のインバータ回路の出力停止または制限と、発熱部材検知手段の検知結果が異常な場合のインバータ回路の出力停止をソフトウェアを介さずに行なうことで、より確実に発煙や発火等を防止できるという有効な効果が得られる。
【０１２８】
また、加熱中はソフトウェアの状態を常に監視することで、ソフトウェア暴走を即座に検知しインバータ回路の出力を停止することで、ソフトウェア暴走時においても発煙や発火等を防止できるという有効な効果が得られる。
【０１２９】
また、インバータ回路とその制御回路との接続を、定着器交換時のドアに連動したスイッチを介して行ない、スイッチがオープン状態（ドア開）の時は、インバータ回路の出力を停止することで、ユーザーが安全に定着器の交換ができるという有効な効果が得られる。
【図面の簡単な説明】
【図１】本発明の一実施の形態である定着装置を備えた画像形成装置の構成図
【図２】図１の画像形成装置に用いられる本発明の一実施の形態である電磁誘導加熱方式による定着装置の構成図
【図３】図２の定着装置を構成する本発明の一実施の形態である加熱ローラの断面図
【図４】図２の定着装置を構成する本発明の一実施の形態である励磁コイル、ショートリングの構成図
【図５】本発明の一実施の形態である電磁誘導加熱方式による定着装置のインバータ回路と制御回路およびその周辺回路を示すブロック図
【図６】図５の電磁誘導加熱方式による印字時の動作を示すタイミングチャート
【図７】図５の電磁誘導加熱方式による加熱を行なう待機時の動作を示すタイミングチャート
【図８】本発明の第二の実施の形態である電磁誘導加熱方式による定着装置の制御回路およびその周辺回路を示すブロック図
【図９】図８の電磁誘導加熱方式による印字時の動作を示すタイミングチャート
【図１０】本発明の第三の実施の形態である電磁誘導加熱方式による定着装置のインバータ回路と制御回路の接続を示すブロック図
【図１１】従来の電磁誘導加熱方式による定着装置の模式図
【符号の説明】
１３０ 加熱ローラ
１４０ 定着ローラ
１５０ 耐熱性ベルト
１８０ 誘導加熱手段
３１０ インバータ回路
３２０ 制御回路
３３０ 発熱部材検知手段
３４０ 回転移動検知手段
３５０ 駆動動作検知手段
３７０ ＣＰＵ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer, and more particularly, to a fixing device using electromagnetic induction.
[0002]
[Prior art]
In recent years, market demands for energy saving and high speed have been increasing for image forming apparatuses such as printers, copiers, and facsimile machines. In order to achieve these required performances, it is important to improve the thermal efficiency of a fixing device used in an image forming apparatus.
[0003]
In an image forming apparatus, an unfixed toner image is recorded on a sheet material, printing paper, photosensitive paper, electrostatic recording paper, or the like by an image transfer method or a direct method by an image forming process such as electrophotographic recording, electrostatic recording, or magnetic recording. Formed on the medium. As a fixing device for fixing an unfixed toner image, a contact heating type fixing device such as a heat roller system, a film heating system, and an electromagnetic induction heating system is widely used.
[0004]
As a fixing device of the electromagnetic induction heating type, in Japanese Patent Application Laid-Open No. Hei 8-22206, Joule heat is generated by an eddy current generated in a heating member, which is a magnetic metal member, by a magnetic field of an induction heating unit including an exciting coil. Techniques for generating electromagnetic induction have been proposed.
[0005]
The configuration of a conventional electromagnetic induction heating type fixing device will be described below. Here, FIG. 11 is a schematic view showing a fixing device using a conventional electromagnetic induction heating method.
[0006]
As shown in FIG. 11, the fixing device includes an excitation coil unit 1001 composed of a ferrite core 1001a and an excitation coil 1001b, a heating roller 1002 composed of a magnetic metal member, a fixing roller 1003 having an elastic layer on its surface, and a heating roller. The fixing belt 1004 includes a fixing belt 1004 having a release layer on a surface layer and being stretched by a roller 1002 and a fixing roller 1003, and a pressing roller 1005 that presses the fixing roller 1003 so as to face the fixing roller 1003. A nip is formed between them. The heating roller 1002, the fixing roller 1003, the fixing belt 1004, and the pressure roller 1005 are driven by driving means (not shown), and rotate and move in the direction of arrow D, respectively.
[0007]
The exciting coil 1001b is energized by an inverter circuit (not shown) based on a result calculated by software so that the fixing belt 1004 maintains a predetermined temperature based on the temperature information detected by the temperature detecting means 1006, and an alternating magnetic field. (Not shown). The alternating magnetic field generated by the exciting coil 1001 b generates an eddy current in the heating roller 1002, and this eddy current is converted into heat (Joule heat) by the electric resistance of the heating roller 1002, causing the heating roller 1002 to generate heat. Heated.
[0008]
In a state where the fixing belt 1004 has risen to a predetermined temperature, an unfixed toner image 1008 formed by an image forming unit (not shown) is provided in a nip formed by the fixing roller 1003 and the pressure roller 1005. When the recording material 1007 is introduced, the recording material 1007 is conveyed to the fixing nip portion by being sandwiched between the fixing belt 1004 and the pressure roller 1005, so that the unfixed toner image 1008 on the recording material 1007 is placed on the recording material 1007. It is fused and fixed.
[0009]
Further, the heating roller 1002, the fixing roller 1003, the fixing belt 1005, the pressure roller 1005, and the temperature detecting means 1006 are configured as a single unit of the fixing device 1009, and can be replaced by a user when the life is over.
[0010]
In the fixing device configured as described above, the heat generation efficiency is improved, and the warm-up can be further reduced. At the exit of the fixing nip, the recording material 1007 that has passed is separated from the surface of the fixing belt 1004 and is conveyed to a discharge tray (not shown).
[0011]
In the fixing device configured as described above, the heat generation efficiency is improved, and the warm-up can be further reduced.
[0012]
[Patent Document 1]
JP-A-8-22206
[0013]
[Problems to be solved by the invention]
In such a fixing device of the electromagnetic induction heating type, the heating section has good heat generation efficiency, but the temperature rises very quickly. There was a safety problem that it was locally heated and smoke and ignite.
[0014]
Further, since the heating value of the heating roller is based on the calculation result of software, there is a safety problem that smoke or fire occurs even when the software runs away.
[0015]
In addition, if the user replaces the fixing device 1009 without turning off the power, or if the user forgets to attach the fixing device and heats the printing, unnecessary electromagnetic waves leak to the user and surrounding devices. Was.
[0016]
Therefore, the present invention provides a driving operation detecting means for detecting that the driving means for driving the heat generating member is operating normally, and a heat generating member rotation movement detecting means for detecting that the heat generating member is rotating and moving normally. It is an object of the present invention to provide a safe fixing device that can stop or limit the output of the inverter circuit when either of the detection results is abnormal.
[0017]
In addition, a heat-generating member detecting means for detecting that the fixing device (heat-generating member) is normally mounted is provided. If the fixing device is not properly mounted, the output of the inverter circuit is stopped to prevent unnecessary leakage of electromagnetic waves. It is an object of the present invention to provide a fixing device that can perform the fixing.
[0018]
Also, the connection between the inverter circuit and its control circuit must be made via a switch linked to the door when the fuser is replaced, etc., and when the switch is open (door open), the output of the inverter circuit must be stopped. It is another object of the present invention to provide a fixing device that allows a user to safely exchange a fixing device.
[0019]
Further, the control circuit stops or limits the output of the inverter circuit when the detection result of either the driving operation detecting means or the heating member rotation movement detecting means is abnormal, and the inverter circuit when the detection result of the heating member detecting means is abnormal. It is an object of the present invention to provide a more reliable and safe fixing device by stopping the output of the fixing device without using software.
[0020]
Another object of the present invention is to provide a safe fixing device capable of immediately detecting software runaway and stopping the output of the inverter circuit by constantly monitoring the state of software during heating.
[0021]
[Means for Solving the Problems]
In order to solve this problem, a heat generating device and a fixing device according to the present invention include a heat generating member, an induction heating unit that is disposed to face the heat generating member, and generates heat by heating the heat generating member by electromagnetic induction. A driving means for moving, a driving operation detecting means for detecting that the driving means is operating normally, a heating member rotation movement detecting means for detecting that the heating member rotates or moves normally, and the guide An inverter circuit that drives a heating unit; and a control circuit that controls the inverter circuit. When the driving operation detection unit or the heating member rotation movement detection unit detects an abnormality, the control circuit includes the inverter circuit. Output can be stopped or limited.
[0022]
Also, a heating member, an induction heating means arranged to face the heating member and causing the heating member to generate heat by electromagnetic induction, a driving means for rotating or moving the heating member, and the driving means are operating normally. Operation detecting means for detecting that the heat generating member is rotating or moving normally, and heat generating member detecting means for detecting that the heat generating member is normally mounted. And an inverter circuit for driving the induction heating means, and a control circuit for controlling the inverter circuit, wherein when the drive operation detection means or the heating member rotation movement detection means detects an abnormality, the control circuit Stops or limits the output of the inverter circuit, and when the heat generating member detecting means detects an abnormality, the control circuit It is of configuration that can stop the output.
[0023]
Also, a heating member, an induction heating means arranged to face the heating member and causing the heating member to generate heat by electromagnetic induction, a driving means for rotating or moving the heating member, and the driving means are operating normally. Operation detecting means for detecting that the heat generating member is rotating or moving normally, and heat generating member detecting means for detecting that the heat generating member is normally mounted. An inverter circuit for driving the induction heating means, a control circuit for controlling the inverter circuit, a door for attaching and detaching the heating member, and a switch for opening and closing in conjunction with opening and closing of the door. The control circuit stops the output of the inverter circuit when the driving operation detecting means or the heating member rotational movement detecting means detects an abnormality. The control circuit stops the output of the inverter circuit when the heating member detecting means detects an abnormality, and the output of the inverter circuit stops when the switch is open. It is a configuration that can be done.
[0024]
Further, the control circuit is configured to stop or limit the output of the inverter circuit without using software.
[0025]
Further, the control circuit is configured to be able to stop the output of the inverter circuit when there is no access from software regularly within a predetermined time.
[0026]
Thereby, a driving operation detecting unit that detects that the driving unit that drives the heating member is operating normally and a heating member rotation movement detecting unit that detects that the heating member is rotating and moving normally are provided. If either of the detection results is abnormal, the output of the inverter circuit can be stopped or limited.
[0027]
In addition, a heat-generating member detecting means for detecting that the fixing device (heat-generating member) is normally mounted is provided. If the fixing device is not properly mounted, the output of the inverter circuit is stopped to prevent unnecessary leakage of electromagnetic waves. Is possible.
[0028]
In addition, the connection between the inverter circuit and its control circuit must be made via a switch linked to the door when the fuser is replaced, and when the switch is open (the door is open), the output of the inverter circuit is stopped. Thus, the user can safely exchange the fixing device.
[0029]
Further, the control circuit stops or limits the output of the inverter circuit when the detection result of either the driving operation detecting means or the heating member rotation movement detecting means is abnormal, and the inverter circuit when the detection result of the heating member detecting means is abnormal. Can be stopped without software.
[0030]
In addition, by constantly monitoring the state of software during heating, it is possible to immediately detect software runaway and stop the output of the inverter circuit.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
According to a first aspect of the present invention, there is provided a heating member, an induction heating unit disposed to face the heating member and causing the heating member to generate heat by electromagnetic induction, a driving unit for rotating or moving the heating member, and a driving unit. A drive operation detecting means for detecting normal operation, a heat generating member rotational movement detecting means for detecting normal rotation or movement of the heat generating member, an inverter circuit for driving the induction heating means, and an inverter circuit. And a control circuit for controlling the output of the inverter circuit when the drive operation detecting means or the heat-generating member rotational movement detecting means detects an abnormality.
[0032]
The invention according to claim 2 of the present invention is directed to a heating member, an induction heating unit disposed to face the heating member and causing the heating member to generate heat by electromagnetic induction, a driving unit for rotating or moving the heating member, and a driving unit. Driving operation detecting means for detecting normal operation, heat generating member rotational movement detecting means for detecting normal rotation or movement of the heat generating member, and detecting that the heat generating member is normally mounted. Heating member detecting means, an inverter circuit for driving the induction heating means, and a control circuit for controlling the inverter circuit, when the driving operation detecting means or the heating member rotation movement detecting means detects an abnormality, the control circuit The control circuit can stop or limit the output of the inverter circuit when the heating member detecting unit detects that the output of the inverter circuit is abnormal or abnormal. It has the effect of say.
[0033]
The invention according to claim 3 of the present invention is characterized in that the heating member, an induction heating means arranged to face the heating member and causing the heating member to generate heat by electromagnetic induction, a driving means for rotating or moving the heating member, and a driving means Driving operation detecting means for detecting normal operation, heat generating member rotation / movement detecting means for detecting normal rotation or movement of the heat generating member, and detecting that the heat generating member is normally mounted Heating member detecting means, an inverter circuit for driving the induction heating means, a control circuit for controlling the inverter circuit, a door for mounting and removing the heating member, and a switch for opening and closing in conjunction with opening and closing of the door. If the driving operation detecting means or the heating member rotational movement detecting means detects an abnormality, the control circuit stops or limits the output of the inverter circuit, If the detected abnormality, the control circuit stops the output of the inverter circuit, when the switch is open, the output of the inverter circuit has the effect that it is possible to stop.
[0034]
According to a fourth aspect of the present invention, in the first to third aspects of the invention, the control circuit can stop or limit the output of the inverter circuit without using software. Having.
[0035]
According to a fifth aspect of the present invention, in the first to fourth aspects of the invention, the control circuit stops the output of the inverter circuit when there is no access from the software periodically within a predetermined time. Has the effect that it becomes possible.
[0036]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 7 and (Table 1) to (Table 6). In these drawings, the same members are denoted by the same reference numerals, and redundant description is omitted.
[0037]
FIG. 1 is a configuration diagram of an image forming apparatus provided with a fixing device using an electromagnetic induction heating system according to an embodiment of the present invention, and FIG. 2 is an embodiment of the present invention used in the image forming apparatus of FIG. FIG. 3 is an exploded view showing a configuration of a heating roller constituting the fixing device of FIG. 2 cut away, and FIG. 4 is an excitation coil and a short ring constituting the fixing device of FIG. FIG. 5 is a block diagram showing an inverter circuit, a control circuit, and peripheral circuits of a fixing device using an electromagnetic induction heating system according to an embodiment of the present invention. FIG. 6 is a timing chart showing an operation at the time of printing by the electromagnetic induction heating method according to one embodiment of the present invention. FIG. 7 is a timing chart showing an operation at the time of standby for performing heating by the electromagnetic induction heating method according to one embodiment of the present invention.
[0038]
First, an outline of an image forming apparatus according to the present invention will be described. The image forming apparatus described in the present embodiment is provided with a developing device for each of the four basic color toners that particularly contribute to the color development of a color image among the devices employing the electrophotographic method, and the transfer member has four color toners. This is a tandem method in which images are superimposed and collectively transferred to a sheet material. However, it is needless to say that the present invention is not limited to the tandem type image forming apparatus, and can be applied to any type of image forming apparatus regardless of the number of developing devices, the presence or absence of the intermediate transfer member, and the like. .
[0039]
In FIG. 1, charging means 20a, 20b, 20c, which uniformly charge the surface of each of the photosensitive drums 10a, 10b, 10c, 10d to a predetermined potential, are provided around the photosensitive drums 10a, 10b, 10c, 10d. Exposure means for forming an electrostatic latent image by irradiating the charged photosensitive drums 10a, 10b, 10c, and 10d with scanning lines 30K, 30C, 30M, and 30Y of laser beams corresponding to image data of a specific color. 30, developing means 40a, 40b, 40c, 40d for visualizing the electrostatic latent images formed on the photosensitive drums 10a, 10b, 10c, 10d, and visible images on the photosensitive drums 10a, 10b, 10c, 10d Transfer means 50a, 50b, 50c, 50d for transferring the converted toner image to an endless intermediate transfer belt (intermediate transfer body) 70, and photosensitive drums 10a, 10b, 0c, the photosensitive drum 10a after the toner image has been transferred to the intermediate transfer belt 70 from 10d, 10b, 10c, cleaning means 60a for removing residual toner remaining 10d, 60b, 60c, 60d are respectively disposed.
[0040]
Here, the exposing means 30 is arranged with a predetermined inclination with respect to the photosensitive drums 10a, 10b, 10c, 10d. The intermediate transfer belt 70 rotates in the direction of arrow A in the illustrated case. In the image forming stations Pa, Pb, Pc, and Pd, a black image, a cyan image, a magenta image, and a yellow image are formed, respectively. Then, the single-color images of the respective colors formed on the photosensitive drums 10a, 10b, 10c, and 10d are sequentially transferred onto the intermediate transfer belt 70 so as to form a full-color image.
[0041]
At the lower part of the apparatus, there is provided a paper feed cassette 100 in which a sheet material (recording medium) 90 such as printing paper is stored. Then, the sheet material 90 is sent out from the sheet feeding cassette 100 to the sheet conveying path one by one by the sheet feeding roller 80.
[0042]
On the sheet transport path, a sheet material transfer roller 110 that contacts the outer peripheral surface of the intermediate transfer belt 70 for a predetermined amount and transfers the color image formed on the intermediate transfer belt 70 to the sheet material 90, A fixing device 120 is provided for fixing the transferred color image to the sheet material 90 by the pressure and heat generated by the rotation of the rollers.
[0043]
Further, the door 125 forms a housing of the image forming apparatus, and is opened and closed when the fixing unit 120 is replaced or jam processing is performed.
[0044]
In the image forming apparatus having such a configuration, first, the charging unit 20a and the exposing unit 30 of the image forming station Pa form the latent image of the black component color of the image information on the photosensitive drum 10a. This latent image is visualized as a black toner image by the developing unit 40a having black toner by the developing unit 40a, and is transferred as a black toner image onto the intermediate transfer belt 70 by the transfer unit 50a.
[0045]
On the other hand, while the black toner image is being transferred to the intermediate transfer belt 70, a latent image of a cyan component color is formed in the image forming station Pb, and then the cyan toner image of the cyan toner is visualized by the developing unit 40b. You. Then, the cyan toner image is transferred by the transfer means 50b of the image station Pb to the intermediate transfer belt 70 where the transfer of the black toner image has been completed at the previous image station Pa, and is superimposed on the black toner image.
[0046]
Hereinafter, image formation is performed for the magenta toner image and the yellow toner image in the same manner, and when the superposition of the four color toner images on the intermediate transfer belt 70 is completed, the paper is fed from the paper feed cassette 100 by the paper feed roller 80. The four color toner images are collectively transferred onto the sheet material 90 by the sheet material transfer roller 110. Then, the transferred toner image is heated and fixed to the sheet material 90 by the fixing device 120, and a full-color image is formed on the sheet material 90.
[0047]
Next, a fixing device used in such an image forming apparatus will be described.
[0048]
As shown in FIG. 2, the fixing device includes a heating roller (heating member) 130 heated by electromagnetic induction of induction heating means 180, a fixing roller 140 arranged in parallel with heating roller 130, An endless belt-shaped heat-resistant belt (toner heating medium) 150, which is stretched between rollers 140, is heated by the heating roller 130, and is rotated in at least one of these rollers in the direction of arrow B; And a pressure roller 160 that is pressed against the fixing roller 140 through the heat roller 150 and rotates in the forward direction with respect to the heat-resistant belt 150.
[0049]
The heating roller 130 is made of a rotating body of a hollow cylindrical magnetic metal member such as iron, cobalt, nickel or an alloy of these metals, and has an outer diameter of, for example, 20 mm, a wall thickness of, for example, 0.3 mm, and has a low heat capacity and a temperature rise. It has a fast configuration.
[0050]
As shown in FIG. 3, both ends of the heating roller 130 are rotatably supported by bearings 132 fixed to a supporting side plate 131 made of a galvanized steel plate. The heating roller 130 is driven to rotate by a driving unit shown in FIG. The heating roller 130 is made of a magnetic material that is an alloy of iron, nickel, and chromium, and is adjusted so that its Curie point is 300 ° C. or higher. The heating roller 130 is formed in a pipe shape having a thickness of 0.3 mm.
[0051]
The surface of the heating roller 130 is coated with a release layer (not shown) made of a fluororesin having a thickness of 20 μm in order to impart release properties. As the release layer, a resin or rubber having good releasability such as PTFE, PFA, FEP, silicone rubber, and fluororubber may be used alone or in combination. When the heating roller 130 is used for fixing a monochrome image, only the releasability may be secured, but when the heating roller 130 is used for fixing a color image, it is desirable to impart elasticity. Need to form a thicker rubber layer.
[0052]
The fixing roller 140 includes a metal core 140a made of, for example, stainless steel, and an elastic member 140b in which heat-resistant silicone rubber is solid or foamed to cover the core 140a. Then, in order to form a fixing nip portion N having a predetermined width between the pressing roller 160 and the fixing roller 140 by the pressing force from the pressing roller 160, the outer diameter is set to about 30 mm and is made larger than that of the heating roller 130. . The elastic member 140b has a thickness of about 3 to 8 mm and a hardness of about 15 to 50 ° (Asker hardness: 6 to 25 ° in JIS A hardness). With this configuration, since the heat capacity of the heating roller 130 is smaller than the heat capacity of the fixing roller 140, the heating roller 130 is rapidly heated, and the warm-up time is reduced.
[0053]
The heat-resistant belt 150 stretched between the heating roller 130 and the fixing roller 140 is heated at a contact portion of the heating roller 130 heated by the induction heating unit 180. Then, the inner surface of the heat resistant belt 150 is continuously heated by the rotation of the heating roller 130 and the fixing roller 140, and as a result, the entire belt is heated.
[0054]
The heat-resistant belt 150 is made of a heat-generating layer made of a metal having magnetism such as iron, cobalt, nickel or the like or an alloy made of them, and a silicone rubber or a fluorine rubber provided so as to cover the surface thereof. And a release layer made of an elastic member such as a composite layer belt (not shown).
[0055]
The use of the composite belt makes it possible to directly heat the belt, improve the heat generation efficiency, and increase the response.
[0056]
Also, even if for some reason, for example, a foreign matter is mixed between the heat-resistant belt 150 and the heating roller 130 to form a gap, even if the heat-generating layer of the heat-resistant belt 150 generates heat due to electromagnetic induction, the heat-resistant belt 150 itself is not heated. Generates heat, so that the temperature non-uniformity is small and the reliability of fixing is increased.
[0057]
In FIG. 2, a pressure roller 160 includes a metal core 160a made of a cylindrical member made of a metal having high thermal conductivity such as copper or aluminum, and heat resistance and toner releasability provided on the surface of the metal core 160a. High elastic member 160b. SUS may be used for the metal core 160a in addition to the above metals.
[0058]
The pressing roller 160 forms a fixing nip portion N that presses the fixing roller 140 via the heat-resistant belt 150 to pinch and convey the sheet material 90. In the present embodiment, the hardness of the pressing roller 160 is By making the fixing roller 140 harder than the fixing roller 140, the pressure roller 160 bites into the fixing roller 140 (and the heat-resistant belt 150), so that the sheet material 90 follows the circumferential shape of the surface of the pressure roller 160. Therefore, the sheet member 90 has an effect of easily separating from the surface of the heat resistant belt 150. The outer diameter of the pressure roller 160 is about 30 mm, which is the same as that of the fixing roller 140, but the wall pressure is about 2 to 5 mm, which is thinner than the fixing roller 140, and the hardness is 20 to 60 ° (Asker hardness: JIS A hardness). As described above, the fixing roller 140 is harder than the fixing roller 140. In the vicinity of the entrance side of the fixing nip portion N, the temperature of the belt inner surface is detected by a temperature detecting means 240 including a thermosensitive element having a high thermal response such as a thermistor disposed in contact with the inner surface of the heat resistant belt 150.
[0059]
Next, the configuration of the induction heating means 180 will be described.
[0060]
The induction heating means 180 for heating the heating roller 130 by electromagnetic induction is arranged to face the outer peripheral surface of the heating roller 130 as shown in FIG. The induction heating means 180 is provided with a support frame (coil guide member) 190 having a storage chamber 200 for storing the heating roller 130 which is curved so as to cover the heating roller 130. The support frame 190 is made of a flame-retardant resin.
[0061]
A portion for detecting the temperature of the thermostat 210 is provided so as to be partially exposed from the support frame 190 toward the heating roller 130 and the heat-resistant belt 150. Thereby, the temperatures of the heating roller 130 and the heat-resistant belt 150 are detected, and when the abnormal temperature is detected, the connection between the exciting coil 220 and the inverter circuit shown in FIG. 5 is forcibly cut off.
[0062]
On the outer peripheral surface of the support frame 190, an exciting coil 220 of a wire bundle, which is a magnetic field generating means and is a bundle of wires whose surfaces are insulated, is wound. The exciting coil 220 is formed by alternately winding a single long exciting coil wire in the axial direction of the heating roller 130 along the support frame 190 (not shown). The length around which the coil is wound is substantially the same as the area where the heat resistant belt 150 and the heating roller 130 are in contact.
[0063]
The excitation coil 220 is connected to the inverter circuit 310 shown in FIG. 5 and is supplied with a high-frequency AC current of 10 kHz to 1 MHz, preferably a high-frequency AC current of 20 kHz to 800 kHz, thereby generating an alternating magnetic field. The alternating magnetic field acts on the heating layer of the heating roller 130 and the heat-resistant belt 150 in the contact area between the heating roller 130 and the heat-resistant belt 150 and in the vicinity thereof. Eddy currents flow.
[0064]
This eddy current generates Joule heat in accordance with the resistance of the heating layer of the heating roller 130 and the heat-resistant belt 150, and the heating roller 130 and the heat-resistant property mainly in the contact area between the heating roller 130 and the heat-resistant belt 150 and in the vicinity thereof. The belt 150 is heated by electromagnetic induction.
[0065]
As shown in FIG. 4, a short ring 230 is provided outside the support frame 190 so as to surround the storage room 200. An eddy current is generated in the short ring 230 in such a direction as to cancel out a leakage magnetic flux leaking to the outside among magnetic fluxes generated by applying a current to the exciting coil 220. When an eddy current is generated, a magnetic field is generated in a direction to cancel the magnetic field of the leakage magnetic flux by Fleming's law, thereby preventing unnecessary radiation due to the leakage magnetic flux.
[0066]
The short ring 230 is made of, for example, highly conductive copper or aluminum. Further, the short ring 230 only needs to be at least at a position where a magnetic flux for canceling the leakage magnetic flux can be generated.
[0067]
An excitation coil core 250 is provided so as to surround the storage room 200 of the support frame 190, and a C-shaped coil core 260 is provided above the excitation coil core 250 so as to straddle the storage room 200 of the support frame 190.
[0068]
By providing the exciting coil core 250 and the C-shaped coil core 260, the inductance of the exciting coil 220 is increased, and the electromagnetic coupling between the exciting coil 220 and the heating roller 130 is improved. For this reason, a large amount of electric power can be supplied to the heating roller 130 even with the same coil current, and a fixing device with a short warm-up time can be realized.
[0069]
A housing 270 that covers the inside of the induction heating means 180 is attached to the opposite side of the heating roller 130 with the excitation coil 220 interposed therebetween. The housing 270 is made of, for example, resin, and is attached to the support frame 190 in a roof shape that covers the C-shaped coil core 260 and the thermostat 210. The housing 270 may be made of a material other than resin. A plurality of heat radiation holes 280 are formed in the housing 270 shown in FIG. 4 so that heat radiated from the internal support frame 190, the exciting coil 220, the C-shaped coil core 260, and the like are released to the outside. .
[0070]
A short ring 290 is attached to the support frame 190 in a shape that does not block the heat radiation holes 280 formed in the housing 270.
[0071]
The short ring 290 is similar to the above-described short ring 230, and is located on the back surface of the C-shaped coil core 260 or the like as shown in FIG. An eddy current is generated in a direction to cancel the leakage magnetic flux, thereby generating a magnetic field in a direction to cancel the magnetic field of the leakage magnetic flux, thereby preventing unnecessary radiation due to the leakage magnetic flux.
[0072]
Next, the configuration of the control circuit 320 and its surroundings will be described with reference to FIG.
[0073]
The control circuit 320 includes a heating member detecting unit 330 that detects that the fixing device 120 including the heating roller 130, the fixing roller 140, and the heat resistant belt 150 is normally mounted, the heating roller 130 or the heat resistant belt 150. Operation detection means 340 for detecting that the rotation means for detecting normal rotation of the heating roller 130, the fixing roller 140, and the heat-resistant belt 150 are normally operated. 350, a CPU 370 for controlling the temperature of the fixing device, and an inverter circuit 310.
[0074]
The control circuit 320 includes an enable generation circuit 321 for generating a signal IHENB for controlling the enable / disable of the output of the inverter circuit 310, a pulse generation circuit 322 for generating a signal IHPOWER for controlling the output power of the inverter circuit 310, and a standby state. , A power setting register 324 that determines the output power of the inverter circuit 310, and an abnormal power register 325 that determines the output power of the inverter circuit 310 when abnormal. When the signal IHENB is “0” or “Hi-Z”, the output of the inverter circuit 310 is disabled (stopped), and when the signal IHENB is “1”, the output is enabled. The signal IHPOWER is a pulse signal, and the output power of the inverter circuit 310 is determined by the ratio (duty) between the high time and the low time. The output power increases as the duty increases (the higher the time is longer than the lower time). For example, the output power is about 300 W when the duty is 30% and about 800 W when the duty is 80%.
[0075]
The mode setting register 323 is a 2-bit register, and its data MOD is written from the CPU 370 via the data bus D and the address bus A. When the data is "0", the mode is a standby mode in which heating is not performed. When "1", mode 1 is a heating standby state (a state in which heating is performed even when the heating roller 130 and the heat-resistant belt 150 are not rotating). When data is "2", a printing state (heating) is set. Mode 2 in which heating is performed only when the roller 130 and the heat-resistant belt 150 are rotating normally.
[0076]
The enable generation circuit 321 receives a signal IHENB from the signal IHON from the CPU 370, the signal FSR from the heating member detection means 330, the signal ROT from the rotational movement detection means 340, the signal LD from the drive detection means 350, and the signal MOD from the mode setting register. Is output as "0" or "1".
[0077]
The power setting register 324 is an 8-bit register, and its data PW is written from the CPU 370 via the data bus D and the address bus A. The larger the data, the higher the output power of the inverter circuit. The abnormal-time power register 325 is an 8-bit register, and its data EPW is a fixed value, which is a value that does not pose a safety problem even if the heating roller 130 and the heat-resistant belt 150 are heated without being rotated.
[0078]
The pulse generation circuit 322 includes a signal ROT from the rotational movement detecting means 340, a signal LD from the drive detecting means 350, a signal PW from the power setting register 324, a signal EPW from the abnormal power register 325, and a signal MOD from the mode setting register. Outputs a pulse signal to the signal IHPOWER.
[0079]
The heat generating member detecting means 330 includes a heat generating member detecting circuit 331 and an optical sensor 332 such as a photo interrupter. When the fixing device 120 including the heating roller 130, the fixing roller 140, the heat-resistant belt 150, and the like is normally mounted, the optical sensor 332 is in a light-shielding state, and the heating member detection circuit 331 outputs “1” to the signal FSR. In a state where it is not properly mounted, the optical sensor 332 is in a transmitting state, and the heat generating member detection circuit 331 outputs "0" to the signal FSR.
[0080]
The rotation movement detecting means 340 includes an encoder plate 341 that rotates in conjunction with the heating roller 130 and the heat resistant belt 150, a rotation movement detection circuit 342, and an optical sensor 343 such as a photo interrupter. The rotation of the encoder plate 341 causes the optical sensor 343 to repeat the light blocking state and the transmitting state. When the repetition period becomes a predetermined time or less, the rotation detection circuit 342 causes the heating roller 130 and the heat resistant belt 150 to rotate normally. And outputs "1" to the signal ROT, and outputs "0" if the repetition period is longer than a predetermined time.
[0081]
The drive means 360 such as a DC brushless motor rotates when the signal MON from the CPU 370 is "1", drives the rotary heating roller 130, the fixing roller 140, and the heat resistant belt 150, and stops when the signal MOT is "0". . The driving operation detecting means 350 using a hall sensor or the like (not shown) outputs a signal LD “1” during a period when the driving means 360 is rotating at a predetermined rotational speed, and outputs “0” during other periods. I do.
[0082]
The CPU 370 controls the temperature of the fixing device based on a ROM 380 in which a program (software) is stored, a RAM 390 as a work area, and a signal TH from the temperature detecting means 240. Further, the CPU 370 can recognize the state of the signal FSR from the heat generating member detecting means, the signal ROT from the rotational movement detecting means, and the signal LD from the driving operation detecting means by the address bus A and the data bus D.
[0083]
Next, the operation of the fixing device at the time of printing will be described with reference to FIG. 6 and (Table 1) to (Table 6).
[0084]
FIG. 6 is a timing chart showing the operation of the fixing device during printing, (Tables 1) to (Table 3) are tables showing the relationship between inputs and outputs of the enable generation circuit 321 and (Tables 4 to 6) are pulses. 4 is a table showing a relationship between an input and an output of a generation circuit 322.
[0085]
[Table 1]

[0086]
[Table 2]

[0087]
[Table 3]

[0088]
[Table 4]

[0089]
[Table 5]

[0090]
[Table 6]

[0091]
First, the CPU 370 confirms that the signal FSR from the heat generating member detecting means is “1”, and writes “2” into the mode setting register 323 (the signal MOD becomes “2”). When the signal FSR is "0", no printing operation is performed. Next, the CPU 370 sets the signal MON to the driving unit 360 to “1”, so that the driving unit 360 starts rotating. When the driving means 360 reaches a predetermined number of revolutions at a predetermined time T1, the driving operation detecting means 350 sets the signal LD to "1", and when the heating roller 130 and the heat resistant belt 150 rotate normally after the predetermined time T2, the rotation movement detecting means. 340 sets the signal ROT to “1”. The CPU confirms that both the signal LD and the signal ROT are “1”, sets the signal IHON to “1”, and writes predetermined data (here, “80H”) to the power setting register 324.
[0092]
When the signal MOD = 2 (at the time of printing), the enable generation circuit 321 in the control circuit 320 has the same state as the signal IHON when the signal FSR, the signal LD, and the signal ROT are all “1” as shown in (Table 3). To the signal IHENB. When the signal MOD = 2 (at the time of printing), as shown in (Table 6), when the signal LD and the signal ROT are all “1”, the pulse generation circuit 322 uses the data set in the power setting register 324. A pulse corresponding to a certain signal PW is output as a signal IHPOWER. In this case, since “80H” is set in the power setting register 324, the signal IHPOWER becomes a pulse with a duty of 50%.
[0093]
Since signal IHENB is enabled, inverter circuit 310 outputs power according to the duty of signal IHPOWER. In this case, since the duty of the signal IHPOWER is 50%, a power of about 500 W is output, and the heating roller 130 and the heat resistant belt 150 are heated.
[0094]
When the final fixed sheet material 90 is conveyed to a paper discharge tray (not shown), the CPU 370 sets the signal IHON to “0”, writes “00H” to the power setting register 324, and then sets the signal MON to “0”. To stop the driving means 360, and the fixing operation ends.
[0095]
Here, the CPU 370 confirms that the signal FSR is "1" and then enables the output of the inverter circuit 310. Also, during printing heating (MOD = 2), the signal FSR becomes "0" for some reason. Then, it is recognized that an abnormality has occurred, the signal IHON is set to "0", "00H" is written to the power setting register 324, and the heating is stopped. Output can be stopped to prevent unnecessary leakage of electromagnetic waves.
[0096]
In addition, during printing heating (MOD = 2), if either the signal LD or the signal ROT becomes “0” for some reason, it is recognized that an abnormality has occurred, the signal IHON is set to “0”, and the power setting register 324 is sent to the power setting register 324. By writing “00H” and stopping the heating, the heating roller 130 and the heat-resistant belt 150 are not locally heated, and smoke and ignition can be prevented.
[0097]
When the above-described abnormality occurs, the control circuit 320 stops heating similarly to the CPU 370 as shown in (Table 3) and (Table 6). In other words, when the above-described abnormality occurs, the heating is stopped without the intervention of software. Therefore, even if the CPU 370 does not stop the heating for some reason at the time of the abnormality, the heating can be surely stopped.
[0098]
Next, the operation of the fixing device in a standby state where heating is performed will be described with reference to FIG. 7 and (Table 1) to (Table 6).
[0099]
First, the CPU 370 confirms that the signal FSR from the heat generating member detecting means is “1”, and writes “1” into the mode setting register 323 (the signal MOD becomes “1”). Next, the signal IHON is set to “1” and predetermined data (here, “40H”) is written to the power setting register 324. This heating in the standby state is heating for keeping the fixing device at about 100 ° C., and low power is set.
[0100]
When the signal MOD = 1 (standby state in which heating is performed), the enable generation circuit 321 in the control circuit 320 changes the same state as the signal IHON to the signal IHENB when the signal FSR is “1” as shown in (Table 2). Output. When the signal MOD = 1 (standby state in which heating is performed), the pulse generation circuit 322 uses the data set in the power setting register 324 regardless of the state of the signal LD and the signal ROT as shown in (Table 5). A pulse corresponding to a certain signal PW is output as a signal IHPOWER. However, even if signal PW is set to a value greater than signal EPW, signal IHPOWER does not take a value greater than signal EPW. Here, “50H” is set as a fixed value of the signal EPW. Also, since “40H” is set in the power setting register 324, the signal IHPOWER is a pulse with a duty of 25%.
[0101]
Since signal IHENB is enabled, inverter circuit 310 outputs power according to the duty of signal IHPOWER. In this case, since the duty of the signal IHPOWER is 25%, about 250 W of power is output, and the heating roller 130 and the heat resistant belt 150 are heated.
[0102]
Here, even if the CPU 370 sets a large value (for example, “FFH”) in the power setting register 324 for some reason, the control circuit 320 does not output a pulse having a value larger than the signal EPW to the signal IHPOWER. In a state where the roller 130 and the heat-resistant belt 150 are not rotating, the heating is not performed with a large power, so that smoke and ignition can be prevented.
[0103]
Next, a second embodiment of the present invention will be described with reference to FIGS. 8, 9, and (Table 7) to (Table 12).
[0104]
FIG. 8 is a block diagram showing a control circuit of a fixing device using an electromagnetic induction heating system according to a second embodiment of the present invention and its peripheral circuits. FIG. 9 is a timing chart showing an operation at the time of printing by the electromagnetic induction heating method of FIG. (Table 7) to (Table 9) are tables showing the relationship between the input and output of the enable generation circuit in the electromagnetic induction heating system according to the second embodiment of the present invention. (Table 10) to (Table 12) are tables showing the relationship between input and output of the pulse generation circuit in the electromagnetic induction heating system according to the second embodiment of the present invention.
[0105]
[Table 7]

[0106]
[Table 8]

[0107]
[Table 9]

[0108]
[Table 10]

[0109]
[Table 11]

[0110]
[Table 12]

[0111]
In FIG. 9, the CPU monitoring circuit 326 monitors the state of the signal TGL, and when the state of the signal TGL changes from “0” to “1” or “1” to “0” within a predetermined time T3, the signal WD changes to “1”. And outputs "0" if there is no change within T3.
[0112]
As shown in (Table 7) to (Table 9), the enable generation circuit 321 outputs the signal IHON as in Table 1 of the first embodiment only when the signal WD is "1". When the signal WD is "0", "0" is always output to the signal IHON.
[0113]
As shown in Table 4, the pulse generation circuit 322 outputs the signal IHPOWER as shown in Table 2 of the first embodiment only when the signal WD is "1". When the signal WD is "0", "0" is always output to the signal IHPOWER.
[0114]
Here, the operation of the fixing device during printing will be described.
[0115]
First, the CPU 370 confirms that the signal FSR from the heat generating member detecting means is “1”, writes “2” into the mode setting register 323, and sets the signal TGL to a state different from the current state. Here, the signal TGL is changed from “0” to “1”, and thereafter, the state is continuously changed every time T4. The CPU monitoring circuit 326 outputs “1” to the signal WD when the state of the signal TGL changes within a predetermined time T3 (time T4 and T3 have a relationship of T4> T3).
[0116]
Next, the CPU 370 sets the signal MON to the driving unit 360 to “1”, so that the driving unit 360 starts rotating. When the driving means 360 reaches a predetermined number of revolutions at a predetermined time T1, the driving operation detecting means 350 sets the signal LD to "1", and when the heating roller 130 and the heat resistant belt 150 rotate normally after the predetermined time T2, the rotation movement detecting means. 340 sets the signal ROT to “1”. The CPU confirms that both the signal LD and the signal ROT are “1”, sets the signal IHON to “1”, and writes predetermined data (here, “80H”) to the power setting register 324.
[0117]
When the signal MOD = 2 (at the time of printing), the enable generation circuit 321 in the control circuit 320 outputs the signal IHON when the signal WD, the signal FSR, the signal LD, and the signal ROT are all “1” as shown in (Table 9). Is output to the signal IHENB. When the signal MOD = 2 (at the time of printing), the signal WD is set in the power setting register 324 when the signal WD, the signal LD, and the signal ROT are all “1” as shown in (Table 12). A pulse corresponding to the signal PW, which is the present data, is output to the signal IHPOWER. Here, since "80H" is set in the power setting register 324, the signal IHPOWER is a pulse with a duty of 50%.
[0118]
Since signal IHENB is enabled, inverter circuit 310 outputs power according to the duty of signal IHPOWER. In this case, since the duty of the signal IHPOWER is 50%, a power of about 500 W is output, and the heating roller 130 and the heat resistant belt 150 are heated.
[0119]
When the final fixed sheet material 90 is conveyed to a discharge tray (not shown), the CPU 370 sets the signal IHON to “0” and writes “00H” to the power setting register 324. Thereafter, the state of the signal TGL is not changed, and the CPU monitoring circuit 326 outputs “0” to the signal WD when the state change of the signal TGL is not performed within T3. Further, the CPU 370 sets the signal MON to "0" to stop the driving means 360, and the fixing operation ends.
[0120]
Here, since the CPU monitoring circuit 326 constantly monitors the signal TGL, even if the CPU 370 runs away during printing heating for some reason, the CPU 370 recognizes the runaway beforehand, and the signal IHENB and the signal IHPOWER become “0”. By stopping the heating, smoke and ignition can be prevented.
[0121]
Next, a third embodiment of the present invention will be described with reference to FIG.
[0122]
FIG. 10 is a block diagram showing a connection between an inverter circuit and a control circuit of a fixing device using an electromagnetic induction heating system according to a third embodiment of the present invention.
[0123]
The switch 400 is a switch linked to opening and closing of a door (not shown) used when exchanging the fixing device. The output signal IHENB from the control circuit 320 is connected to the inverter circuit 310 via the switch 400, and becomes "Hi-Z" when the above-mentioned door (not shown) is opened (when the fixing device is replaced), and The circuit enters the output stop state. In a normal printing state, the door is closed, and the signal IHENB is transmitted to the inverter circuit as it is.
[0124]
As described above, the connection between the control circuit 320 and the inverter circuit 310 is performed via the switch linked to the door when the fixing unit is replaced, and when the switch is in the open state (door open), the output of the inverter circuit is stopped. Thus, the user can safely exchange the fixing device.
[0125]
【The invention's effect】
As described above, according to the present invention, the drive operation detecting means for detecting that the drive means for driving the heat generating member is operating normally and the heat generating member for detecting that the heat generating member is rotating and moving normally By providing a rotational movement detecting means and stopping or restricting the output of the inverter circuit when either of the detection results is abnormal, it is possible to obtain an effective effect of preventing smoke and ignition.
[0126]
Further, a heating member detecting means for detecting that the fixing device (heating member) is normally mounted is provided, and if it is not properly mounted, the output of the inverter circuit is stopped to prevent unnecessary leakage of electromagnetic waves. An effective effect is obtained.
[0127]
Further, the control circuit stops or limits the output of the inverter circuit when the detection result of either the driving operation detection means or the heating member rotation movement detection means is abnormal, and the inverter circuit when the detection result of the heating member detection means is abnormal. By stopping the output without using software, it is possible to obtain an effective effect that smoke and ignition can be more reliably prevented.
[0128]
Also, by monitoring the software status constantly during heating, the software runaway is immediately detected and the output of the inverter circuit is stopped, so that an effective effect that smoke and fire can be prevented even during software runaway can be obtained. Can be
[0129]
Also, the connection between the inverter circuit and its control circuit is made via a switch linked to the door when the fuser is replaced, and when the switch is open (door open), the output of the inverter circuit is stopped. There is an effective effect that the user can safely exchange the fixing device.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an image forming apparatus including a fixing device according to an embodiment of the present invention.
FIG. 2 is a configuration diagram of an electromagnetic induction heating type fixing device according to an embodiment of the present invention used in the image forming apparatus of FIG. 1;
FIG. 3 is a cross-sectional view of a heating roller according to an embodiment of the present invention which forms the fixing device of FIG. 2;
FIG. 4 is a configuration diagram of an exciting coil and a short ring according to an embodiment of the present invention which constitutes the fixing device of FIG. 2;
FIG. 5 is a block diagram showing an inverter circuit, a control circuit, and peripheral circuits of a fixing device using an electromagnetic induction heating system according to an embodiment of the present invention;
FIG. 6 is a timing chart showing an operation at the time of printing by the electromagnetic induction heating method of FIG. 5;
7 is a timing chart showing an operation at the time of standby for performing heating by the electromagnetic induction heating method of FIG. 5;
FIG. 8 is a block diagram showing a control circuit of a fixing device based on an electromagnetic induction heating system and a peripheral circuit thereof according to a second embodiment of the present invention;
9 is a timing chart showing an operation at the time of printing by the electromagnetic induction heating method of FIG.
FIG. 10 is a block diagram showing connection between an inverter circuit and a control circuit of a fixing device using an electromagnetic induction heating system according to a third embodiment of the present invention.
FIG. 11 is a schematic diagram of a fixing device using a conventional electromagnetic induction heating method.
[Explanation of symbols]
130 heating roller
140 fixing roller
150 heat resistant belt
180 Induction heating means
310 Inverter circuit
320 control circuit
330 Heating member detection means
340 Rotational movement detecting means
350 Driving operation detecting means
370 CPU

Claims (5)

A heat-generating member, an induction heating means arranged to face the heat-generating member and generating heat by electromagnetic induction, a driving means for rotating or moving the heat-generating member, and that the driving means is operating normally. A drive operation detecting means for detecting, a heat generating member rotational movement detecting means for detecting that the heat generating member rotates or moves normally, an inverter circuit for driving the induction heating means, and a control circuit for controlling the inverter circuit. And a control circuit that stops or limits the output of the inverter circuit when the driving operation detecting unit or the heating member rotational movement detecting unit detects an abnormality. A heat-generating member, an induction heating means arranged to face the heat-generating member and causing the heat-generating member to generate heat by electromagnetic induction, a driving means for rotating or moving the heat-generating member, and that the driving means is operating normally. Driving operation detecting means for detecting, heating member rotation movement detecting means for detecting that the heating member rotates or moves normally, and heating member detecting means for detecting that the heating member is normally mounted, An inverter circuit for driving the induction heating means, and a control circuit for controlling the inverter circuit, wherein when the drive operation detection means or the heating member rotation movement detection means detects an abnormality, the control circuit is The output of the inverter circuit is stopped or limited, and when the heating member detecting means detects an abnormality, the control circuit outputs the output of the inverter circuit. Fixing apparatus characterized by stopping. A heat-generating member, an induction heating means arranged to face the heat-generating member and causing the heat-generating member to generate heat by electromagnetic induction, a driving means for rotating or moving the heat-generating member, and that the driving means is operating normally. Driving operation detecting means for detecting, heating member rotation movement detecting means for detecting that the heating member rotates or moves normally, and heating member detecting means for detecting that the heating member is normally mounted, An inverter circuit for driving the induction heating means, a control circuit for controlling the inverter circuit, a door for attaching and detaching the heating member, and a switch for opening and closing in conjunction with opening and closing of the door, The control circuit stops the output of the inverter circuit when the driving operation detecting means or the heating member rotation movement detecting means detects an abnormality, or The control circuit stops the output of the inverter circuit when the heating member detecting means detects an abnormality, and the output of the inverter circuit stops when the switch is in an open state. Fixing device. The control circuit stops or restricts the output of the inverter circuit without using software when the drive operation detection unit, the heating member rotation movement detection unit, or the heating member detection unit detects an abnormality. The fixing device according to claim 1, wherein 5. The fixing device according to claim 1, wherein the control circuit stops the output of the inverter circuit when there is no access from software periodically within a predetermined time.

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