JP4529249B2

JP4529249B2 - Fixing device

Info

Publication number: JP4529249B2
Application number: JP2000226577A
Authority: JP
Inventors: 和徳松尾; 政博醒井; 智之野口
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2000-07-27
Filing date: 2000-07-27
Publication date: 2010-08-25
Anticipated expiration: 2020-07-27
Also published as: JP2002040839A

Description

【０００１】
【発明の属する技術分野】
本発明は、複写機やファクシミリ、プリンタなどの静電記録式の画像形成装置に使用される定着装置に関するものである。
【０００２】
【従来の技術】
昨今、ＯＡ機器の省エネルギー化の動向から、プリンタや複写機等に用いられる定着装置も省エネルギーおよびクイックスタートの要求が高まりつつある。そして、その要求に応えるため、従来の一般的な熱ローラ方式の定着装置に代わり、定熱容量の定着ベルトを用いたベルト定着方式の定着装置が提案されている。
【０００３】
また、従来から、加熱ローラの加熱手段としてハロゲンランプや抵抗発熱体等が用いられている。これらはそれ自体に熱容量がある等の理由から加熱ローラの発熱効率が悪く、さらに発熱効率を向上させる加熱手段として、電磁誘導加熱方式の研究も行われている。
【０００４】
以下に電磁誘導方式を用いた定着装置について説明する。
【０００５】
図１０は電磁誘導加熱方式が用いられた従来の定着装置を示す模式図、図１１は図１０の定着装置の要部を示す説明図、図１２は図１０の定着装置の動作を示すフローチャートである。
【０００６】
図示する定着装置は、導電性部材から構成されて誘導加熱手段１の電磁誘導により加熱される加熱ローラ２と、表層に弾性体層を有して加熱ローラ２と平行に配置された定着ローラ３と、表層に離型層が形成され、加熱ローラ２と定着ローラ３とに張架されて加熱ローラ２により加熱されるとともにこれらのローラの回転により周回動する無端帯状の定着ベルト５と、定着ベルト５を介して定着ローラ３に圧接されるとともに定着ベルト５に対して順方向に回転する加圧ローラ４とから構成されている。
【０００７】
そして、定着ローラ３と加圧ローラ４との押圧力により、定着ベルト５と加圧ローラ４との間に所定幅のニップ部が形成される。
【０００８】
加熱ローラ２と定着ローラ３とに張架された定着ベルト５は、誘導加熱手段１に加熱される加熱ローラ２との接触部位で加熱される。そして、ローラ２，３の回転に伴う回転によって定着ベルト５の内面が連続的に加熱され、結果としてベルト全体に渡って加熱される。
【０００９】
電磁誘導により加熱ローラ２を加熱する誘導加熱手段１は、磁界発生手段である励磁コイル１ｂと、励磁コイル１ｂの外側において励磁コイル１ｂが巻き回された強磁性体よりなるフェライトコア１ａが配置されている。なお、励磁コイル１ｂは、発振回路が周波数可変とされた励磁回路（図示せず）に接続されている。
【００１０】
そして、加熱ローラ２と定着ベルト５との接触領域およびその近傍部において、励磁コイル１ｂにより発生した交番磁界が加熱ローラ２に作用し、その内部では交番磁界の変化を妨げる方向に渦電流が流れる。
【００１１】
この渦電流が加熱ローラ２の抵抗に応じたジュール熱を発生させ、主として加熱ローラ２と定着ベルト５との接触領域ａ（図１１）において加熱ローラ２が電磁誘導発熱して加熱され、このような加熱ローラ２により定着ベルト５が加熱される。
【００１２】
このようにして加熱された定着ベルト５のニップ部の入口側近傍における温度を測定するため、定着ベルト５の内面側に当接して、サーミスタなどの熱応答性の高い感温素子からなる温度検出手段６が配置されている。そして、温度検出手段６が検出する温度に基づき、定着ベルト５が一定の温度を保つように励磁回路により励磁コイル１ｂへの通電が制御され、誘導加熱手段１による加熱ローラ２の発熱温度がコントロールされる。
【００１３】
以上のように構成された定着装置では発熱効率も向上し、さらなるウォームアップの短縮が可能である。また、ウォームアップの短縮が可能になったことで、定着装置を常に暖めて待機状態にしておく必要がなくなり、消費電力を小さくすることが可能である。
【００１４】
【発明が解決しようとする課題】
このような電磁誘導加熱方式の定着装置において、誘導加熱手段１は発熱効率が良い反面、温度上昇が非常に速いため、定着ベルト５を回転しない状態で加熱してしまうと、温度検出位置と加熱位置とが離れているので、温度検出位置でのベルトの温度は上がらない。
【００１５】
すると、加熱ＯＮの信号が送り続けられて誘導加熱手段１の近傍が局所的に加熱され、温度が異常上昇するという問題があった。
【００１６】
次に、このような定着装置が用いられた従来の画像形成装置の動作について、図１２のフローチャートを用いて説明する。
【００１７】
プリンタが印字開始の信号を受信すると、先ず、定着駆動用のモータにモータＯＮの信号が送られる（Ｓ２１）。
【００１８】
次に、モータのリモート信号を確認して（Ｓ２２）、リモートが確認できた場合は、誘導加熱の励磁回路に通電されて加熱が開始される（Ｓ２３）。また、モータのリモートが確認されなかった場合は、エラー検出され（Ｓ３０）、印字動作はキャンセルされる。
【００１９】
Ｓ２３において加熱が開始されたならば、温度検出手段６により検出された定着ベルト５の温度が印字開始温度に到達したかが判断される（Ｓ２４）。そして、到達していれば、定着ベルト５が制御温度で制御されて印字が開始される（Ｓ２５）。また、予め決められた時間内に印字開始温度に到達しなかった場合には、温度検知手段６の異常、誘導加熱の励磁回路の異常、定着ベルト５の回転停止などの不具合の可能性があるため、エラー検出され（Ｓ３１）、印字動作がキャンセルされる。
【００２０】
印字が終了したならば（Ｓ２６）、誘導加熱手段１への通電がＯＦＦされ（Ｓ２７）、定着ベルト５の温度を検出する温度検知手段６により検出された温度が、予め決められた駆動停止温度に到達したかどうかが判断される（Ｓ２８）。そして、駆動停止温度に到達したならば、定着駆動用モータにモータＯＦＦの信号が送られ（Ｓ２９）、印字動作が終了する。また、予め決められた時間内に駆動停止温度に到達しなかった場合には、誘導加熱手段１の励磁回路への通電がＯＦＦされていない可能性があるため、エラー検出され（Ｓ３２）、Ｓ２７に戻る。
【００２１】
このように定着装置駆動用のモータをスタートさせ、モータのクロック信号確認後に加熱を開始する従来の技術では、そのモータの駆動対象である定着装置への駆動伝達（モータより下流側）に不具合があり、モータの駆動力が定着ベルトへ伝わらなかった場合には定着ベルト５が回転していない可能性があり、局所的な温度の異常上昇の問題がある。
【００２２】
ここで、温度検知手段６による定着ベルト５の温度と加熱ＯＮ信号の関係から定着ベルト５の回転状態を推測することが考えられるが、制御プログラムが複雑になるのみならず誤検知の可能性もあり、有効な手段とはいえない。
【００２３】
そこで、本発明は、定着ベルトの回転状態を確実に検出することのできる定着装置を提供することを目的とする。
【００２４】
【課題を解決するための手段】
この課題を解決するために、本発明の定着装置は、誘導加熱手段の電磁誘導により加熱される加熱ローラと、加熱ローラと平行に配置された定着ローラと、加熱ローラと定着ローラとに張架されて加熱ローラにより加熱されるとともにこれらのローラによって回転される無端状の定着ベルトと、加熱ローラと定着ベルトとの接触領域以外の定着ベルトに当接して温度を検出する温度検出手段と、定着ベルトに形成された少なくとも一つの検知孔と、定着ベルトの回転に伴う検知孔の定着ベルトの回転方向への移動を検知する検知手段と、定着ベルトを介して定着ローラに圧接されるとともに定着ベルトに対して順方向に回転してニップ部を形成する加圧ローラとを有し、検知手段の検知結果に基づいて定着ベルトの移動が確認されると誘導加熱手段による加熱を開始するとともに、誘導加熱手段による加熱が終了し、温度検出手段により検出された温度が予め決められた温度に到達すると定着ベルトの回転を停止する構成としたものである。
【００２５】
このように検知孔の移動を検知手段で検知することにより、定着ベルトの回転状態を確実に検出することが可能になる。
【００２６】
【発明の実施の形態】
本発明の請求項１に記載の発明は、誘導加熱手段の電磁誘導により加熱される加熱ローラと、加熱ローラと平行に配置された定着ローラと、加熱ローラと定着ローラとに張架されて加熱ローラにより加熱されるとともにこれらのローラによって回転される無端状の定着ベルトと、加熱ローラと定着ベルトとの接触領域以外の定着ベルトに当接して温度を検出する温度検出手段と、定着ベルトに形成された少なくとも一つの検知孔と、定着ベルトの回転に伴う検知孔の定着ベルトの回転方向への移動を検知する検知手段と、定着ベルトを介して定着ローラに圧接されるとともに定着ベルトに対して順方向に回転してニップ部を形成する加圧ローラとを有し、検知手段の検知結果に基づいて定着ベルトの移動が確認されると誘導加熱手段による加熱を開始するとともに、誘導加熱手段による加熱が終了し、温度検出手段により検出された温度が予め決められた温度に到達すると定着ベルトの回転を停止する定着装置であり、検知孔の移動を検知手段で検知することにより、定着ベルトの回転状態を確実に検出することが可能になるという作用を有する。
【００２７】
本発明の請求項２に記載の発明は、誘導加熱手段の電磁誘導により加熱される加熱ローラと、加熱ローラの回転軸に取り付けられた遮光手段と、加熱ローラの回転に伴う遮光手段の回転を検知する検知手段と、加熱ローラと平行に配置された定着ローラと、加熱ローラと定着ローラとに張架されて加熱ローラにより加熱されるとともにこれらのローラによって回転される無端状の定着ベルトと、加熱ローラと定着ベルトとの接触領域以外の定着ベルトに当接して温度を検出する温度検出手段と、定着ベルトを介して定着ローラに圧接されるとともに定着ベルトに対して順方向に回転してニップ部を形成する加圧ローラとを有し、検知手段の検知結果に基づいて定着ベルトの移動が確認されると誘導加熱手段による加熱を開始するとともに、誘導加熱手段による加熱が終了し、温度検出手段により検出された温度が予め決められた温度に到達すると定着ベルトの回転を停止する定着装置であり、遮光手段の回転を検知手段で検知することにより、加熱ローラを介して定着ベルトの回転状態を確実に検出することが可能になるという作用を有する。
【００２８】
本発明の請求項３に記載の発明は、誘導加熱手段の電磁誘導により加熱される加熱ローラと、加熱ローラと平行に配置された定着ローラと、定着ローラの回転軸に取り付けられた遮光手段と、定着ローラの回転に伴う遮光手段の回転を検知する検知手段と、加熱ローラと定着ローラとに張架されて加熱ローラにより加熱されるとともにこれらのローラによって回転される無端状の定着ベルトと、加熱ローラと定着ベルトとの接触領域以外の定着ベルトに当接して温度を検出する温度検出手段と、定着ベルトを介して定着ローラに圧接されるとともに定着ベルトに対して順方向に回転してニップ部を形成する加圧ローラとを有し、検知手段の検知結果に基づいて定着ベルトの移動が確認されると誘導加熱手段による加熱を開始するとともに、誘導加熱手段による加熱が終了し、温度検出手段により検出された温度が予め決められた温度に到達すると定着ベルトの回転を停止する定着装置であり、遮光手段の回転を検知手段で検知することにより、定着ローラを介して定着ベルトの回転状態を確実に検出することが可能になるという作用を有する。
【００２９】
本発明の請求項４に記載の発明は、誘導加熱手段の電磁誘導により加熱される加熱ローラと、加熱ローラと平行に配置された定着ローラと、定着ローラを回転駆動する駆動手段に取り付けられた遮光手段と、駆動手段の回転に伴う遮光手段の回転移動を検知する検知手段と、加熱ローラと定着ローラとに張架されて加熱ローラにより加熱されるとともにこれらのローラによって回転される無端状の定着ベルトと、加熱ローラと定着ベルトとの接触領域以外の定着ベルトに当接して温度を検出する温度検出手段と、定着ベルトを介して定着ローラに圧接されるとともに定着ベルトに対して順方向に回転してニップ部を形成する加圧ローラとを有し、検知手段の検知結果に基づいて定着ベルトの移動が確認されると誘導加熱手段による加熱を開始するとともに、誘導加熱手段による加熱が終了し、温度検出手段により検出された温度が予め決められた温度に到達すると定着ベルトの回転を停止する定着装置であり、遮光手段の回転移動を検知手段で検知することにより、駆動手段を介して定着ベルトの回転状態を確実に検出することが可能になるという作用を有する。
【００３０】
以下、本発明の実施の形態について、図１から図９を用いて説明する。なお、これらの図面において同一の部材には同一の符号を付しており、また、重複した説明は省略されている。
【００３１】
図１は本発明の一実施の形態である電磁誘導加熱方式が用いられた定着装置の要部を正面から示す模式図、図２は図１の定着装置を側面から示す模式図、図３は本発明の他の実施の形態である電磁誘導加熱方式が用いられた定着装置の要部を正面から示す模式図、図４は図３の定着装置を側面から示す模式図、図５は本発明のさらに他の実施の形態である電磁誘導加熱方式が用いられた定着装置の要部を正面から示す模式図、図６は図５の定着装置を側面から示す模式図、図７は本発明のさらに他の実施の形態である電磁誘導加熱方式が用いられた定着装置の要部を正面から示す模式図、図８は図７の定着装置を側面から示す模式図、図９は本発明の実施の形態における定着装置の動作を示すフローチャートである。
【００３２】
図１および図２に示す定着装置は、導電性部材から構成されて誘導加熱手段１の電磁誘導により加熱される加熱ローラ２と、表層に弾性体層を有して加熱ローラ２と平行に配置された定着ローラ３と、表層に離型層が形成され、加熱ローラ２と定着ローラ３とに張架されて加熱ローラ２により加熱されるとともに定着ローラ３を駆動する駆動ギヤ９の回転により周回動する無端帯状の定着ベルト５と、定着ベルト５を介して定着ローラ３に圧接されるとともに定着ベルト５に対して順方向に回転する加圧ローラ４とから構成されている。
【００３３】
そして、定着ローラ３と加圧ローラ４との押圧力により、定着ベルト５と加圧ローラ４との間に所定幅のニップ部が形成される。
【００３４】
加熱ローラ２と定着ローラ３とに張架された定着ベルト５は、誘導加熱手段１に加熱される加熱ローラ２との接触部位で加熱される。そして、ローラ２，３の回転に伴う回転によって定着ベルト５の内面が連続的に加熱され、結果としてベルト全体に渡って加熱される。
【００３５】
電磁誘導により加熱ローラ２を加熱する誘導加熱手段１は、磁界発生手段である励磁コイル１ｂと、励磁コイル１ｂの外側において励磁コイル１ｂが巻き回された強磁性体よりなるフェライトコア１ａが配置されている。なお、励磁コイル１ｂは、発振回路が周波数可変とされた励磁回路（図示せず）に接続されている。
【００３６】
そして、加熱ローラ２と定着ベルト５との接触領域およびその近傍部において、励磁コイル１ｂにより発生した交番磁界が加熱ローラ２に作用し、その内部では交番磁界の変化を妨げる方向に渦電流が流れる。
【００３７】
この渦電流が加熱ローラ２の抵抗に応じたジュール熱を発生させ、主として加熱ローラ２と定着ベルト５との接触領域において加熱ローラ２が電磁誘導発熱して加熱され、このような加熱ローラ２により定着ベルト５が加熱される。
【００３８】
このようにして加熱された定着ベルト５のニップ部の入口側近傍における温度を測定するため、定着ベルト５の内面側に当接して、サーミスタなどの熱応答性の高い感温素子からなる温度検出手段６が配置されている。そして、温度検出手段６が検出する温度に基づき、定着ベルト５が一定の温度を保つように励磁回路により励磁コイル１ｂへの通電が制御され、誘導加熱手段１による加熱ローラ２の発熱温度がコントロールされる。
【００３９】
定着ベルト５の幅方向の端部には、検知孔８が全周にわたって複数形成されている。そして、定着ベルト５の回転に伴う検知孔８の定着ベルト５の回転方向への移動を検知するために、透過型センサ（検知手段）７が設けられている。なお、検知孔８は定着ベルト５の一箇所にのみ形成されていてもよい。
【００４０】
したがって、検知孔８の移動を透過型センサ７で検知することにより、定着ベルト５の回転状態を確実に検出することが可能になる。そして、これにより、定着ベルト５が回転されていない状態で誘導加熱手段１により加熱された加熱ローラ２により定着ベルト５の温度が異常上昇するという事態を回避することが可能になる。
【００４１】
次に、本発明の他の実施の形態を図３および図４を用いて説明する。
【００４２】
ここでは、検知孔８を透過型センサ７で検知するのではなく、図示するように、定着ベルト５により従動回転される加熱ローラ２の回転軸に、加熱ローラ２と同位相で回転する遮光部材（遮光手段）１０ａを取り付け、この遮光部材１０ａの回転を透過型センサ７で検知している。
【００４３】
このように、加熱ローラ２の回転軸に設けられた遮光部材１０ａの回転を透過型センサ７で検知するようにしても、加熱ローラ２の回転状態を介して定着ベルト５の回転を確実に検出することが可能になる。
【００４４】
次に、本発明のさらに他の実施の形態を図５および図６を用いて説明する。
【００４５】
ここでは、定着ベルト５を回転駆動する定着ローラ３の回転軸に、定着ローラ３と同位相で回転する遮光部材（遮光手段）１０ｂを取り付け、この遮光部材１０ｂの回転を透過型センサ７で検知している。
【００４６】
このように、定着ローラ３の回転軸に設けられた遮光部材１０ｂの回転を透過型センサ７で検知するようにしても、定着ローラ３の回転状態を介して定着ベルト５の回転を確実に検出することが可能になる。
【００４７】
次に、本発明のさらに他の実施の形態を図７および図８を用いて説明する。
【００４８】
ここでは、定着ベルト５を回転駆動する駆動ギヤ９に、駆動ギヤ９と同位相で回転移動する遮光部材（遮光手段）１０ｃを取り付け、この遮光部材１０ｃの回転移動を透過型センサ７で検知している。
【００４９】
このように、駆動ギヤ９に設けられた遮光部材１０ｃの回転移動を透過型センサ７で検知するようにしても、駆動ギヤ９の回転状態を介して定着ベルト５の回転を確実に検出することが可能になる。
【００５０】
ここで、本実施の形態の定着装置の動作について、図９のフローチャートを用いて説明する。
【００５１】
プリンタが印字開始の信号を受信すると、先ず、定着駆動用のモータにモータＯＮの信号が送られる（Ｓ１）。
【００５２】
次に、透過型センサ７の検出結果に基づいて定着ベルト５が回転しているかどうかが確認され（Ｓ２）、定着ベルト５の回転状態が確認されたときには誘導加熱の励磁回路に通電されて加熱が開始される（Ｓ３）。また、定着ベルト５の回転状態が確認されなかったときは、エラー検出され（Ｓ１０）、印字動作はキャンセルされる。
【００５３】
Ｓ３において加熱が開始されたならば、温度検出手段６により検出された定着ベルト５の温度が印字開始温度に到達したかが判断される（Ｓ４）。そして、到達していれば、定着ベルト５が制御温度で制御されて印字が開始される（Ｓ５）。また、予め決められた時間内に印字開始温度に到達しなかった場合には、温度検知手段６の異常、誘導加熱の励磁回路の異常、定着ベルト５の回転停止などの不具合の可能性があるため、エラー検出され（Ｓ１１）、印字動作がキャンセルされる。
【００５４】
印字が終了したならば（Ｓ６）、誘導加熱手段１への通電がＯＦＦされ（Ｓ７）、定着ベルト５の温度を検出する温度検知手段６により検出された温度が、予め決められた駆動停止温度に到達したかどうかが判断される（Ｓ８）。そして、駆動停止温度に到達したならば、定着駆動用モータにモータＯＦＦの信号が送られ（Ｓ９）、印字動作が終了する。また、予め決められた時間内に駆動停止温度に到達しなかった場合には、誘導加熱手段１の励磁回路への通電がＯＦＦされていない可能性があるため、エラー検出され（Ｓ１２）、Ｓ７に戻る。
【００５５】
このように、本実施の形態によれば、定着ベルト５、加熱ローラ２、定着ローラ３または駆動ギヤ９の回転状態を透過型センサ７で検知することが可能になる。
【００５６】
そして、定着ベルト５の回転状態が確認されなかったときはエラー検出するようになっているので、定着ベルト５が回転されていない状態で誘導加熱手段１により加熱された加熱ローラ２により定着ベルト５の温度が異常上昇するという事態を回避することが可能になる。
【００５７】
【発明の効果】
以上のように、本発明によれば、検知手段で定着ベルトの回転を直接または加熱ローラ、定着ローラ、駆動手段を介して間接に検知しているので、定着ベルトの回転状態を確実に検出することが可能になるという有効な効果が得られる。
【００５８】
これにより、定着ベルトが回転されていない状態で誘導加熱手段により加熱された加熱ローラにより定着ベルトの温度が異常上昇するという事態を回避することが可能にな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電磁誘導加熱方式が用いられた定着装置の要部を正面から示す模式図
【図２】図１の定着装置を側面から示す模式図
【図３】本発明の他の実施の形態である電磁誘導加熱方式が用いられた定着装置の要部を正面から示す模式図
【図４】図３の定着装置を側面から示す模式図
【図５】本発明のさらに他の実施の形態である電磁誘導加熱方式が用いられた定着装置の要部を正面から示す模式図
【図６】図５の定着装置を側面から示す模式図
【図７】本発明のさらに他の実施の形態である電磁誘導加熱方式が用いられた定着装置の要部を正面から示す模式図
【図８】図７の定着装置を側面から示す模式図
【図９】本発明の実施の形態における定着装置の動作を示すフローチャート
【図１０】電磁誘導加熱方式が用いられた従来の定着装置を示す模式図
【図１１】図１０の定着装置の要部を示す説明図
【図１２】図１０の定着装置の動作を示すフローチャート
【符号の説明】
１誘導加熱手段
２加熱ローラ
３定着ローラ
４加圧ローラ
５定着ベルト
７透過型センサ（検知手段）
８検知孔
９駆動ギヤ（駆動手段）
１０ａ，１０ｂ，１０ｃ遮光部材（遮光手段）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixing device used in an electrostatic recording type image forming apparatus such as a copying machine, a facsimile, or a printer.
[0002]
[Prior art]
In recent years, due to the trend of energy saving in OA equipment, there is an increasing demand for energy saving and quick start for fixing devices used in printers and copiers. In order to meet the demand, a belt fixing type fixing device using a fixing belt having a constant heat capacity has been proposed instead of a conventional general heat roller type fixing device.
[0003]
Conventionally, a halogen lamp, a resistance heating element, or the like is used as a heating means of the heating roller. These have poor heat generation efficiency of the heating roller because they have their own heat capacity, and electromagnetic induction heating methods have been studied as heating means for further improving the heat generation efficiency.
[0004]
A fixing device using an electromagnetic induction method will be described below.
[0005]
FIG. 10 is a schematic diagram showing a conventional fixing device using an electromagnetic induction heating method, FIG. 11 is an explanatory diagram showing the main part of the fixing device in FIG. 10, and FIG. 12 is a flowchart showing the operation of the fixing device in FIG. is there.
[0006]
The illustrated fixing device includes a heating roller 2 made of a conductive member and heated by electromagnetic induction of induction heating means 1, and a fixing roller 3 having an elastic layer as a surface layer and arranged in parallel with the heating roller 2. A release layer is formed on the surface layer, is stretched between the heating roller 2 and the fixing roller 3 and is heated by the heating roller 2 and rotates endlessly by the rotation of these rollers; The pressure roller 4 is pressed against the fixing roller 3 via the belt 5 and rotates in the forward direction with respect to the fixing belt 5.
[0007]
A nip portion having a predetermined width is formed between the fixing belt 5 and the pressure roller 4 by the pressing force between the fixing roller 3 and the pressure roller 4.
[0008]
The fixing belt 5 stretched between the heating roller 2 and the fixing roller 3 is heated at a contact portion with the heating roller 2 heated by the induction heating means 1. The inner surface of the fixing belt 5 is continuously heated by the rotation accompanying the rotation of the rollers 2 and 3, and as a result, the entire belt is heated.
[0009]
The induction heating means 1 that heats the heating roller 2 by electromagnetic induction includes an exciting coil 1b that is a magnetic field generating means, and a ferrite core 1a made of a ferromagnetic material around which the exciting coil 1b is wound outside the exciting coil 1b. ing. The exciting coil 1b is connected to an exciting circuit (not shown) whose oscillation circuit has a variable frequency.
[0010]
An alternating magnetic field generated by the exciting coil 1b acts on the heating roller 2 in the contact area between the heating roller 2 and the fixing belt 5 and in the vicinity thereof, and an eddy current flows in a direction that prevents the change of the alternating magnetic field therein. .
[0011]
This eddy current generates Joule heat according to the resistance of the heating roller 2, and the heating roller 2 is heated by electromagnetic induction heat mainly in the contact area a (FIG. 11) between the heating roller 2 and the fixing belt 5, and thus The fixing belt 5 is heated by the heating roller 2.
[0012]
In order to measure the temperature in the vicinity of the inlet side of the nip portion of the fixing belt 5 heated in this way, the temperature detection is made of a thermosensitive element such as a thermistor that is in contact with the inner surface side of the fixing belt 5. Means 6 are arranged. Then, based on the temperature detected by the temperature detection means 6, the energization to the excitation coil 1b is controlled by the excitation circuit so that the fixing belt 5 maintains a constant temperature, and the heat generation temperature of the heating roller 2 by the induction heating means 1 is controlled. Is done.
[0013]
In the fixing device configured as described above, the heat generation efficiency is improved and the warm-up can be further shortened. In addition, since the warm-up can be shortened, it is not necessary to always warm the fixing device to a standby state, and the power consumption can be reduced.
[0014]
[Problems to be solved by the invention]
In such an electromagnetic induction heating type fixing device, the induction heating means 1 has good heat generation efficiency, but the temperature rises very fast. Therefore, if the fixing belt 5 is heated without being rotated, the temperature detection position and the heating are detected. Since the position is distant, the belt temperature at the temperature detection position does not rise.
[0015]
Then, the heating ON signal is continuously sent, the vicinity of the induction heating means 1 is locally heated, and the temperature rises abnormally.
[0016]
Next, the operation of a conventional image forming apparatus using such a fixing device will be described with reference to the flowchart of FIG.
[0017]
When the printer receives a print start signal, first, a motor ON signal is sent to the fixing drive motor (S21).
[0018]
Next, the remote signal of the motor is confirmed (S22). If the remote is confirmed, the induction heating excitation circuit is energized and heating is started (S23). If the remote motor is not confirmed, an error is detected (S30) and the printing operation is cancelled.
[0019]
If heating is started in S23, it is determined whether the temperature of the fixing belt 5 detected by the temperature detecting means 6 has reached the printing start temperature (S24). If it has reached, the fixing belt 5 is controlled at the control temperature and printing is started (S25). If the print start temperature is not reached within a predetermined time, there is a possibility that the temperature detecting means 6 is abnormal, the induction heating excitation circuit is abnormal, the fixing belt 5 is stopped rotating, or the like. Therefore, an error is detected (S31), and the printing operation is canceled.
[0020]
When the printing is completed (S26), the power supply to the induction heating unit 1 is turned off (S27), and the temperature detected by the temperature detecting unit 6 that detects the temperature of the fixing belt 5 is a predetermined drive stop temperature. Is determined (S28). When the drive stop temperature is reached, a motor OFF signal is sent to the fixing drive motor (S29), and the printing operation is completed. If the drive stop temperature is not reached within a predetermined time, the energization to the excitation circuit of the induction heating means 1 may not be turned off, so an error is detected (S32) and S27. Return to.
[0021]
As described above, in the conventional technique in which the fixing device driving motor is started and heating is started after the clock signal of the motor is confirmed, there is a problem in the drive transmission ( downstream from the motor ) to the fixing device that is the driving target of the motor. If the driving force of the motor is not transmitted to the fixing belt, there is a possibility that the fixing belt 5 is not rotating, and there is a problem of local abnormal temperature rise.
[0022]
Here, it is conceivable to estimate the rotation state of the fixing belt 5 from the relationship between the temperature of the fixing belt 5 by the temperature detection means 6 and the heating ON signal. However, the control program becomes complicated, and there is a possibility of erroneous detection. Yes, it is not an effective means.
[0023]
SUMMARY An advantage of some aspects of the invention is that it provides a fixing device capable of reliably detecting the rotation state of a fixing belt.
[0024]
[Means for Solving the Problems]
In order to solve this problem, a fixing device of the present invention includes a heating roller that is heated by electromagnetic induction of an induction heating unit, a fixing roller that is arranged in parallel to the heating roller, and a tension roller that is stretched between the heating roller and the fixing roller. An endless fixing belt which is heated by the heating roller and rotated by these rollers, a temperature detecting means for detecting the temperature by contacting the fixing belt other than the contact area between the heating roller and the fixing belt, and fixing At least one detection hole formed in the belt, detection means for detecting movement of the detection hole in the rotation direction of the fixing belt as the fixing belt rotates, and the fixing belt being pressed against the fixing roller via the fixing belt have a pressure roller to form a nip portion to rotate in the forward direction relative, guided movement of the fixing belt is confirmed based on the detection results of the detecting means pressurizing Starts the heating by means, induction heating means heating is finished by is obtained by a configuration for stopping the rotation of the fixing belt and the temperature detected reaches a predetermined temperature by the temperature detection means.
[0025]
Thus, by detecting the movement of the detection hole by the detection means, the rotation state of the fixing belt can be reliably detected.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, a heating roller heated by electromagnetic induction of the induction heating means, a fixing roller arranged in parallel with the heating roller, and the heating roller and the fixing roller are stretched and heated. An endless fixing belt heated by the rollers and rotated by these rollers, temperature detecting means for detecting the temperature by contacting the fixing belt other than the contact area between the heating roller and the fixing belt, and formed on the fixing belt At least one detection hole formed therein, detection means for detecting movement of the detection hole in the rotation direction of the fixing belt accompanying rotation of the fixing belt, pressure contacted with the fixing roller via the fixing belt, and against the fixing belt It has a pressure roller to form a nip portion to rotate in the forward direction, by the induction heating means and the movement is confirmed of the fixing belt on the basis of the detection result detecting means pressurizing It starts the induction heating means heating is finished by a fixing device for stopping the rotation of the fixing belt and the temperature detected reaches a predetermined temperature by the temperature detection means, detecting a movement of the detection hole means By detecting at, the rotation state of the fixing belt can be reliably detected.
[0027]
According to a second aspect of the present invention, there is provided a heating roller heated by electromagnetic induction of the induction heating means, a light shielding means attached to a rotating shaft of the heating roller, and rotation of the light shielding means accompanying the rotation of the heating roller. Detection means for detecting, a fixing roller arranged in parallel with the heating roller, an endless fixing belt stretched between the heating roller and the fixing roller and heated by the heating roller and rotated by these rollers; A temperature detecting means for detecting the temperature by contacting the fixing belt other than the contact area between the heating roller and the fixing belt, and a pressure nip that is pressed against the fixing roller via the fixing belt and rotates in the forward direction with respect to the fixing belt. part possess a pressure roller to form a, starts the heating by the induction heating means and the movement of the fixing belt is confirmed based on the detection result of the detection means, induction Heating is completed by the heating means, a fixing device for stopping the rotation of the fixing belt and the temperature detected reaches a predetermined temperature by the temperature detection means, by detecting the detection means the rotation of the shielding means, This has the effect that the rotation state of the fixing belt can be reliably detected via the heating roller.
[0028]
According to a third aspect of the present invention, there is provided a heating roller heated by electromagnetic induction of the induction heating means, a fixing roller arranged in parallel with the heating roller, and a light shielding means attached to the rotating shaft of the fixing roller. Detecting means for detecting the rotation of the light shielding means accompanying the rotation of the fixing roller; an endless fixing belt stretched between the heating roller and the fixing roller and heated by the heating roller and rotated by these rollers; A temperature detecting means for detecting the temperature by contacting the fixing belt other than the contact area between the heating roller and the fixing belt, and a pressure nip that is pressed against the fixing roller via the fixing belt and rotates in the forward direction with respect to the fixing belt. part possess a pressure roller to form a, starts the heating by the induction heating means and the movement of the fixing belt is confirmed based on the detection result of the detection means, induced Heating is completed by the heating means, a fixing device for stopping the rotation of the fixing belt and the temperature detected reaches a predetermined temperature by the temperature detection means, by detecting the detection means the rotation of the shielding means, This has the effect that the rotation state of the fixing belt can be reliably detected via the fixing roller.
[0029]
The invention according to claim 4 of the present invention is attached to a heating roller heated by electromagnetic induction of the induction heating means, a fixing roller arranged in parallel with the heating roller, and a driving means for rotationally driving the fixing roller. A light-shielding means, a detection means for detecting the rotational movement of the light-shielding means accompanying the rotation of the driving means, and an endless shape that is stretched between the heating roller and the fixing roller and heated by the heating roller and rotated by these rollers A fixing belt, temperature detecting means for detecting a temperature by contacting the fixing belt other than a contact area between the heating roller and the fixing belt, and a pressure contact with the fixing roller via the fixing belt and a forward direction with respect to the fixing belt; rotation to have a pressure roller that forms a nip portion starts heating by the induction heating means and the movement of the fixing belt on the basis of the detection result detecting means is confirmed Rutotomoni, induction heating means heating is finished by a fixing device for stopping the rotation of the fixing belt and the temperature detected reaches a predetermined temperature by the temperature detection means, the detection means rotational movement of the shielding means By detecting it, there is an effect that the rotation state of the fixing belt can be reliably detected via the driving means.
[0030]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. In these drawings, the same members are denoted by the same reference numerals, and redundant description is omitted.
[0031]
FIG. 1 is a schematic diagram showing the main part of a fixing device using an electromagnetic induction heating system according to an embodiment of the present invention from the front, FIG. 2 is a schematic diagram showing the fixing device of FIG. 1 from the side, and FIG. FIG. 4 is a schematic diagram showing the main part of a fixing device using an electromagnetic induction heating method according to another embodiment of the present invention from the front, FIG. 4 is a schematic diagram showing the fixing device of FIG. 3 from the side, and FIG. FIG. 6 is a schematic diagram showing the main part of a fixing device using an electromagnetic induction heating method, which is still another embodiment of the present invention, from the front, FIG. 6 is a schematic diagram showing the fixing device of FIG. 5 from the side, and FIG. FIG. 8 is a schematic diagram showing the main part of a fixing device using an electromagnetic induction heating method as another embodiment from the front, FIG. 8 is a schematic diagram showing the fixing device of FIG. 7 from the side, and FIG. 6 is a flowchart showing the operation of the fixing device in the embodiment.
[0032]
The fixing device shown in FIGS. 1 and 2 includes a heating roller 2 made of a conductive member and heated by electromagnetic induction of the induction heating means 1, and an elastic body layer on the surface layer and arranged in parallel with the heating roller 2. A release layer is formed on the fixing roller 3 and the surface layer. The release roller is stretched around the heating roller 2 and the fixing roller 3 and is heated by the heating roller 2 and rotates around the driving gear 9 that drives the fixing roller 3. An endless belt-like fixing belt 5 that moves, and a pressure roller 4 that is pressed against the fixing roller 3 via the fixing belt 5 and rotates in the forward direction with respect to the fixing belt 5.
[0033]
A nip portion having a predetermined width is formed between the fixing belt 5 and the pressure roller 4 by the pressing force between the fixing roller 3 and the pressure roller 4.
[0034]
The fixing belt 5 stretched between the heating roller 2 and the fixing roller 3 is heated at a contact portion with the heating roller 2 heated by the induction heating means 1. The inner surface of the fixing belt 5 is continuously heated by the rotation accompanying the rotation of the rollers 2 and 3, and as a result, the entire belt is heated.
[0035]
The induction heating means 1 that heats the heating roller 2 by electromagnetic induction includes an exciting coil 1b that is a magnetic field generating means, and a ferrite core 1a made of a ferromagnetic material around which the exciting coil 1b is wound outside the exciting coil 1b. ing. The exciting coil 1b is connected to an exciting circuit (not shown) whose oscillation circuit has a variable frequency.
[0036]
An alternating magnetic field generated by the exciting coil 1b acts on the heating roller 2 in the contact area between the heating roller 2 and the fixing belt 5 and in the vicinity thereof, and an eddy current flows in a direction that prevents the change of the alternating magnetic field therein. .
[0037]
This eddy current generates Joule heat corresponding to the resistance of the heating roller 2, and the heating roller 2 is heated by electromagnetic induction heat mainly in the contact area between the heating roller 2 and the fixing belt 5. The fixing belt 5 is heated.
[0038]
In order to measure the temperature in the vicinity of the inlet side of the nip portion of the fixing belt 5 heated in this way, the temperature detection is made of a thermosensitive element such as a thermistor that is in contact with the inner surface side of the fixing belt 5. Means 6 are arranged. Then, based on the temperature detected by the temperature detection means 6, the energization to the excitation coil 1b is controlled by the excitation circuit so that the fixing belt 5 maintains a constant temperature, and the heat generation temperature of the heating roller 2 by the induction heating means 1 is controlled. Is done.
[0039]
A plurality of detection holes 8 are formed at the end of the fixing belt 5 in the width direction over the entire circumference. In order to detect the movement of the detection hole 8 in the rotation direction of the fixing belt 5 accompanying the rotation of the fixing belt 5, a transmission type sensor (detecting means) 7 is provided. The detection hole 8 may be formed only at one place of the fixing belt 5.
[0040]
Accordingly, the rotation state of the fixing belt 5 can be reliably detected by detecting the movement of the detection hole 8 with the transmission sensor 7. As a result, it is possible to avoid a situation in which the temperature of the fixing belt 5 is abnormally increased by the heating roller 2 heated by the induction heating unit 1 when the fixing belt 5 is not rotated.
[0041]
Next, another embodiment of the present invention will be described with reference to FIGS.
[0042]
Here, the detection hole 8 is not detected by the transmissive sensor 7, but, as shown in the figure, a light shielding member that rotates on the rotating shaft of the heating roller 2 driven and rotated by the fixing belt 5 in the same phase as the heating roller 2. (Light shielding means) 10 a is attached, and the transmission sensor 7 detects the rotation of the light shielding member 10 a.
[0043]
As described above, even if the rotation of the light shielding member 10 a provided on the rotation shaft of the heating roller 2 is detected by the transmission type sensor 7, the rotation of the fixing belt 5 is reliably detected through the rotation state of the heating roller 2. It becomes possible to do.
[0044]
Next, still another embodiment of the present invention will be described with reference to FIGS.
[0045]
Here, a light shielding member (light shielding means) 10 b that rotates in the same phase as the fixing roller 3 is attached to the rotation shaft of the fixing roller 3 that rotationally drives the fixing belt 5, and the rotation of the light shielding member 10 b is detected by the transmission type sensor 7. is doing.
[0046]
Thus, even if the rotation of the light shielding member 10 b provided on the rotation shaft of the fixing roller 3 is detected by the transmission type sensor 7, the rotation of the fixing belt 5 is reliably detected through the rotation state of the fixing roller 3. It becomes possible to do.
[0047]
Next, still another embodiment of the present invention will be described with reference to FIGS.
[0048]
Here, a light-shielding member (light-shielding means) 10c that rotates and moves in the same phase as the drive gear 9 is attached to a drive gear 9 that rotationally drives the fixing belt 5, and the rotational movement of the light-shielding member 10c is detected by the transmission type sensor 7. ing.
[0049]
As described above, even if the rotational movement of the light shielding member 10 c provided in the drive gear 9 is detected by the transmission sensor 7, the rotation of the fixing belt 5 can be reliably detected through the rotation state of the drive gear 9. Is possible.
[0050]
Here, the operation of the fixing device of the present embodiment will be described with reference to the flowchart of FIG.
[0051]
When the printer receives a print start signal, first, a motor ON signal is sent to the fixing drive motor (S1).
[0052]
Next, whether or not the fixing belt 5 is rotating is confirmed based on the detection result of the transmission type sensor 7 (S2). When the rotation state of the fixing belt 5 is confirmed, the induction heating excitation circuit is energized and heated. Is started (S3). If the rotation state of the fixing belt 5 is not confirmed, an error is detected (S10), and the printing operation is canceled.
[0053]
If heating is started in S3, it is determined whether the temperature of the fixing belt 5 detected by the temperature detecting means 6 has reached the printing start temperature (S4). If it has reached, the fixing belt 5 is controlled at the control temperature and printing is started (S5). If the print start temperature is not reached within a predetermined time, there is a possibility that the temperature detecting means 6 is abnormal, the induction heating excitation circuit is abnormal, the fixing belt 5 is stopped rotating, or the like. Therefore, an error is detected (S11), and the printing operation is canceled.
[0054]
When printing is completed (S6), the energization to the induction heating unit 1 is turned off (S7), and the temperature detected by the temperature detection unit 6 that detects the temperature of the fixing belt 5 is a predetermined drive stop temperature. It is determined whether or not (S8). When the drive stop temperature is reached, a motor OFF signal is sent to the fixing drive motor (S9), and the printing operation is completed. Further, if the drive stop temperature is not reached within a predetermined time, the energization to the excitation circuit of the induction heating means 1 may not be turned off, so an error is detected (S12) and S7. Return to.
[0055]
As described above, according to the present embodiment, the rotation state of the fixing belt 5, the heating roller 2, the fixing roller 3, or the drive gear 9 can be detected by the transmission type sensor 7.
[0056]
When the rotation state of the fixing belt 5 is not confirmed, an error is detected. Therefore, the fixing belt 5 is heated by the heating roller 2 heated by the induction heating means 1 while the fixing belt 5 is not rotated. It is possible to avoid a situation in which the temperature of the battery rises abnormally.
[0057]
【The invention's effect】
As described above, according to the present invention, since the rotation of the fixing belt is detected directly by the detection unit or indirectly through the heating roller, the fixing roller, and the driving unit, the rotation state of the fixing belt is reliably detected. The effective effect that it becomes possible is acquired.
[0058]
Accordingly, an effective effect is obtained that it is possible to avoid a situation in which the temperature of the fixing belt is abnormally increased by the heating roller heated by the induction heating unit in a state where the fixing belt is not rotated.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the main part of a fixing device using an electromagnetic induction heating method according to an embodiment of the present invention from the front side. FIG. 2 is a schematic diagram showing the fixing device of FIG. FIG. 4 is a schematic diagram showing the main part of a fixing device using an electromagnetic induction heating method according to another embodiment of the present invention from the front. FIG. 4 is a schematic diagram showing the fixing device of FIG. 3 from the side. FIG. 6 is a schematic diagram showing a main part of a fixing device using an electromagnetic induction heating method according to still another embodiment of the present invention from the front. FIG. 6 is a schematic diagram showing the fixing device of FIG. 5 from the side. FIG. 8 is a schematic diagram showing the main part of a fixing device using an electromagnetic induction heating method according to still another embodiment of the present invention from the front. FIG. 8 is a schematic diagram showing the fixing device of FIG. 7 from the side. FIG. 10 is a flowchart showing the operation of the fixing device in the embodiment. Flowchart [EXPLANATION OF SYMBOLS] showing the operation of need the explanatory view showing the principal part of the fixing device in the schematic diagram FIG. 11 FIG. 10 showing the conventional fixing device 12 is a fixing device of FIG. 10
DESCRIPTION OF SYMBOLS 1 Induction heating means 2 Heating roller 3 Fixing roller 4 Pressure roller 5 Fixing belt 7 Transmission type sensor (detection means)
8 Detection hole 9 Drive gear (drive means)
10a, 10b, 10c Light shielding member (light shielding means)

Claims

A heating roller heated by electromagnetic induction of induction heating means;
A fixing roller disposed in parallel with the heating roller;
An endless fixing belt that is stretched between the heating roller and the fixing roller and heated by the heating roller and rotated by these rollers;
Temperature detecting means for detecting a temperature in contact with the fixing belt other than a contact area between the heating roller and the fixing belt;
At least one detection hole formed in the fixing belt;
Detection means for detecting movement of the detection hole in the rotation direction of the fixing belt with rotation of the fixing belt;
Have a pressure roller to form a nip portion to rotate in a forward direction with respect to the fixing belt while being pressed against the fixing roller via the fixing belt,
When the movement of the fixing belt is confirmed based on the detection result of the detection means, the heating by the induction heating means is started, the heating by the induction heating means is finished, and the temperature detected by the temperature detection means is A fixing device , wherein when the temperature reaches a predetermined temperature, the rotation of the fixing belt is stopped .

A heating roller heated by electromagnetic induction of induction heating means;
A light shielding means attached to the rotating shaft of the heating roller;
Detecting means for detecting rotation of the light shielding means accompanying rotation of the heating roller;
A fixing roller disposed in parallel with the heating roller;
An endless fixing belt that is stretched between the heating roller and the fixing roller and heated by the heating roller and rotated by these rollers;
Temperature detecting means for detecting a temperature in contact with the fixing belt other than a contact area between the heating roller and the fixing belt;
Have a pressure roller to form a nip portion to rotate in a forward direction with respect to the fixing belt while being pressed against the fixing roller via the fixing belt,
When the movement of the fixing belt is confirmed based on the detection result of the detection means, the heating by the induction heating means is started, the heating by the induction heating means is finished, and the temperature detected by the temperature detection means is A fixing device , wherein when the temperature reaches a predetermined temperature, the rotation of the fixing belt is stopped .

A heating roller heated by electromagnetic induction of induction heating means;
A fixing roller disposed in parallel with the heating roller;
A light shielding means attached to the rotation shaft of the fixing roller;
Detecting means for detecting rotation of the light shielding means accompanying rotation of the fixing roller;
An endless fixing belt that is stretched between the heating roller and the fixing roller and heated by the heating roller and rotated by these rollers;
Temperature detecting means for detecting a temperature in contact with the fixing belt other than a contact area between the heating roller and the fixing belt;
Have a pressure roller to form a nip portion to rotate in a forward direction with respect to the fixing belt while being pressed against the fixing roller via the fixing belt,
When the movement of the fixing belt is confirmed based on the detection result of the detection means, the heating by the induction heating means is started, the heating by the induction heating means is finished, and the temperature detected by the temperature detection means is A fixing device , wherein when the temperature reaches a predetermined temperature, the rotation of the fixing belt is stopped .

A heating roller heated by electromagnetic induction of induction heating means;
A fixing roller disposed in parallel with the heating roller;
A light shielding means attached to a driving means for rotationally driving the fixing roller;
Detecting means for detecting rotational movement of the light shielding means accompanying rotation of the driving means;
An endless fixing belt that is stretched between the heating roller and the fixing roller and heated by the heating roller and rotated by these rollers;
Temperature detecting means for detecting a temperature in contact with the fixing belt other than a contact area between the heating roller and the fixing belt;
Have a pressure roller to form a nip portion to rotate in a forward direction with respect to the fixing belt while being pressed against the fixing roller via the fixing belt,
When the movement of the fixing belt is confirmed based on the detection result of the detection means, the heating by the induction heating means is started, the heating by the induction heating means is finished, and the temperature detected by the temperature detection means is A fixing device , wherein when the temperature reaches a predetermined temperature, the rotation of the fixing belt is stopped .