JP2005049390A - Fixing device - Google Patents
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、主に電子写真方式によって画像形成を行う複写機、プリンタ等の画像形成装置に用いられる、電磁誘導方式の定着装置に関するものである。
【０００２】
【従来の技術】
図４は従来の典型的な定着装置の説明図である。定着装置内には、内部にハロゲンヒータ１４４等の熱源を有する定着ローラ１０１とこれに圧接して定着ニップ部を形成する加圧ローラ１０８が配設してある。
【０００３】
定着ローラ１０１の温度は、温度検知手段としてのサーミスタ１１１が定着ローラ１０１の外周面に接触して温度を検知し、その検知信号によりハロゲンヒータのＯＮ／ＯＦＦ制御を行なっている。
【０００４】
ここで、実際に制御したい温度は、定着ローラ１０１と加圧ローラ１０８との定着ニップ部Ｎでの温度である。しかし、定着ニップ部Ｎの表面温度を直接検知することはできない。その代わりとして、定着ニップ部以外の定着ローラ１０１の温度を検知して、定着ローラ１０１の定着ニップ部の温度を予測して制御を行なっている。
【０００５】
また、定着ローラ１０１の温度は、制御部等の故障による暴走で異常に高温になることがある。このような異常時に、ヒータへの電力を断つため、定着ローラ１０１の表面に異常時の電力遮断手段としてサーモスイッチ１３１が備えられている。
【０００６】
定着ローラ１０１には、該ローラの外側表面に、不図示のトナー離型層があり、ＰＴＦＥ１０〜５０μｍやＰＦＡ１０〜５０μｍで構成されている。また、トナー離型層の内側にはゴム層を用いる構成も公知とされている。
【０００７】
不図示の転写部位において静電的に形成されたトナー像を担持する記録材Ｓが記録材搬送路Ｈ（一点鎖線）を矢印Ｃ方向から定着ニップ部Ｎに搬送される。
【０００８】
また、図５に示すように、磁束を発生させる磁束発生手段４と、前記磁束発生手段の発生磁束の作用により電磁誘導発熱する誘導発熱体１（定着ローラ）とを有し、記録材上の画像を加熱する誘導加熱の手法を用いた定着装置が提案されている。
【０００９】
誘導加熱装置の場合では、前記定着ローラの内面に前記定着ローラの温度を検知する検知手段を設けた定着装置も提案されている（特許文献１参照）。
【００１０】
【特許文献１】
特開２００２−１０８１２３号公報
【００１１】
【発明が解決しようとする課題】
しかし、上記の定着装置では、以下のような問題がある。
【００１２】
上記ハロゲンランプを用いた定着装置においては、定着ローラ１０１の温度検知手段であるサーミスタ１１１や異常温度検知手段であるサーモスイッチ１３１が定着ローラ１０１の外表面に接触している。
【００１３】
このため、定着ローラ１０１と温度検知手段との間に異物（トナーや紙片）が挟まったり定着ローラ１０１に紙が巻きついたりすると、定着ローラと温度検知手段が適切に接触しなくなる。よって、定着ローラの温度を実温度よりも低いと誤検知してしまい、定着ローラの温度を更に上げようとヒータへの電力を過剰に供給してしまう。従って、定着ローラの温度は所望の制御温度よりも過度に上昇し、近傍の構造部品を故障させてしまう恐れがあった。
【００１４】
また特許文献１のように、電磁誘導加熱の定着ローラ内面に温度検知手段を設けて温度制御する定着器では、次のような問題を抱えている。
【００１５】
定着ローラ１０１の温調制御は、定着ローラ１０１の外周面温度を適切に制御することが目的である。本構成では、定着ローラ内面に温度検知手段を設けて定着ローラ外周面の温度制御をしている。
【００１６】
しかし、定着ローラ外周面の異物付着等により、定着ローラ外周面の性状が著しく変化した場合に、定着ローラの内周面から外周面への熱伝導状態が変化しまう。このため、定着ローラ内周面の温度検知手段によって適切な定着ローラ外周面の温度を正確に検知制御することが困難となる。従って、記録紙Ｓに十分な熱供給が成されずに定着不足などの画像不良を伴う可能性があった。
【００１７】
そこで、本発明は上述の問題を鑑みたものである。
【００１８】
その目的は、定着ローラと温度検知手段との間に異物（トナーや紙片）が挟まったりすることにより、定着ローラ温度が急激に異常温度になることを防止すると伴に、定着ローラ表面性状が急激に変化しても定着ローラ外周面の温度低下による定着不良の発生を防止することにある。
【００１９】
【課題を解決するための手段】
本発明は、上記課題を解決すべく、
通電することで磁束を発生する磁束発生手段と、
前記磁束発生手段に通電する通電手段と、
前記磁束発生手段が発生する磁束の作用により電磁誘導発熱する誘導発熱体と、
前記誘導発熱体の温度を検知する温度検知手段と、
前記温度検知手段の検知温度に基き、前記通電手段の通電する通電量を制御する制御手段と、
を有し、前記誘導発熱体の熱により転写材にトナーを定着する定着装置であって、
前記温度検知手段は、前記誘導発熱体の内面の温度を検知する第１の温度検知手段と、
前記誘導発熱体の外面の温度を検知する第２の温度検知手段とを設け、
前記制御手段は前記第１の温度検知手段と前記第２の温度検知手段で得られた温度情報に基いて異常検知することで解決している。
【００２０】
【発明の実施の形態】
（実施例１）
以下、図１を用いて本発明の実施形態の説明をする。
【００２１】
図１は本実施例の主要構成部である誘導加熱定着部の模式断面図である。図５と同じ要素に対しては同じ番号を付してある。
【００２２】
１は鉄など高透磁率の部材で中空円筒状に形成された定着ローラであり、１ｍｍ以下の薄肉に成形されている。４は磁束発生手段で６の磁束制御芯材としてのフェライトコアとその周りに巻回された導電コイル５で構成されている。１１は定着ローラ１の外周に接して温度を測定するよう設置された外面温度検知手段（第２の温度検知手段）であるサーミスタである。１２は定着ローラ１を挟んでサーミスタ１１に対して略対向位置に設けられた内面温度検知手段（第１の温度検知手段）であるサーミスタである。このように定着ローラを挟んで略対向位置にサーミスタを設けることにより、定着ローラ円周方向での温度むらなどに影響することなく定着ローラ内周面及び外周面の温度を検知することができるため、円周上の任意の位置にて定着ローラ内周面と外周面の温度差をより正確に検知することができ、定着ローラの適切な温調制御が可能となる。但し、前記外面温度検知手段１１、内面温度検知手段１２が必ずしも対向していなくても、例えば外面温度検知手段１１の定着ローラ１に対する設置位置Ａ及び内面温度検知手段１２の定着ローラ１に対する設置位置Ｂとすると、円弧ＡＢを定着ローラ１の回転速度で割って算出した時間分だけずらして内外面温度検知手段の出力結果を比較することで、定着ローラ円周方向での温度むらなどに影響することなく定着ローラの内周面及び外周面の温度を検知することもできる。
【００２３】
９は温度制御部（制御手段）で以下の過昇温防止部（不図示）と温度調整部（不図示）を含んでいる。すなわち、外面温度検知手段の出力に対応する検知温度Ｔｏｕｔと基準温度Ｔ１を比較し、
Ｔｏｕｔ≧Ｔ１
のとき不図示の励磁電源へ駆動停止信号（ＳＴＯＰ）を出力する第１の過昇温防止比較部（不図示）と、内面温度検知手段の出力に対応する検知温度Ｔｉｎと基準温度Ｔ２を比較し、
Ｔｉｎ≧Ｔ２
のとき不図示の励磁電源へ駆動停止信号（ＳＴＯＰ）を出力する第２の過昇温防止比較部（不図示）と、外面温度検知手段の検知温度Ｔｏｕｔと内面温度検知手段の検知温度Ｔｉｎの温度差△Ｔ（＝Ｔｉｎ−Ｔｏｕｔ）と基準温度Ｔｎを比較し、
△Ｔ≧Ｔｎ
のとき不図示の励磁電源へ駆動停止信号（ＳＴＯＰ）を出力する第３の過昇温防止比較部（不図示）とを含んでおり、さらに外面温度検知手段の出力Ｔｏｕｔと基準温度Ｔｔを比較して、差をできるだけ少なくするように電源へ制御信号（ＰＯＷＥＲ）を出力する温度調整部（不図示）を含んでいる。
【００２４】
なお、コイル５が定着ローラ１の内面に配置されている場合は、一般に内面温度の方が外面温度より高いので
Ｔ２＞Ｔ１
となるように設定されている。また、１０は定着ローラ１へのシートの巻きつきを防止する分離爪である。
【００２５】
図２、図３は当実施例の定着器で加熱制御を行ったときのスタンバイ及びコピー時の温度上昇波形である。外面温度検知手段の検知温度Ｔｏｕｔと内面温度検知手段の検知温度Ｔｉｎの加熱開始から温度推移が示されている。
【００２６】
不図示の駆動手段により定着ローラ１を回転させつつ、コイルへの電力投入を行うことでサーミスタ１１、１２の検知温度はほぼ同時に上昇していく。定着ローラ温度の加熱開始時は，立ち上がり時間を短縮する為、投入電力は最大電力を投入している。そして定着ローラ温度がＴｔに到達するとＴｏｕｔが
Ｔｏｕｔ≒Ｔｔ
となるように制御手段である温度調整部からの出力に応じて励磁電源（不図示）は電力を印加する。このように、定着ローラ１は定着ローラ内面温度ではなく、外面温度により温度制御しているので、定着ローラ１の外側の温度を正確に制御することができる。しかし、この加熱中に何らかの異常などでローラの温度が上昇し、サーミスタ１１やサーミスタ１２の検知温度Ｔｏｕｔ、Ｔｉｎが基準温度Ｔ１、Ｔ２にまで達すると過昇温防止比較部（不図示）がＳＴＯＰ信号を出力し、励磁電源は動作を停止する。（図２中のａ〜ｄ曲線の×ポイント）
また、図３の曲線ｅ〜ｋように、ローラの内外面の温度差をみて、前記温度差ΔＴが所定温度Ｔｎ以上差が開くと過昇温防止比較部（不図示）がＳＴＯＰ信号を出力し、励磁電源は動作を停止する。
【００２７】
図３の曲線ｅ〜ｋは上記温度制御によって異常と判断して通電を停止した場合を示している。（図３中のｅ〜ｋ曲線の×ポイント）例えば、定着ローラ異物付着などにより、外面温度検知手段１１の感度が低下し、定着ローラ外周温度を上げようと、過剰な電力を投入し、内周面の温度が異常昇温し、△Ｔ≧Ｔｎ［ｄｅｇ］となる場合や、内面または外面温度検知手段どちらか一方の故障により△Ｔ≧Ｔｎとなり、異常と判断する等が挙げられる。
【００２８】
このように本発明は、図２のように上限値を設けて異常判断する場合はローラ温度が高温であるＴ１、Ｔ２にならなければ異常を検知できなかったが、図３のように定着ローラ内外の温度差をみることで異常を検知するため、図３の曲線ｅ、ｆのようにローラ温度が低い状態でも、素早く異常を検知することができる。従って、装置本体、もしくは定着装置の動作制限をよりはやくかけられるため、装置としてのダウンタイムを低減することが可能となる。
【００２９】
なお、所定の温度差Ｔｎは外面温度検知手段１１及び内面温度検知手段１２の温度検知分解能Ｔｓｔｅｐにより制限される。上記定着ローラの温度差を検知する際、温度検知手段の温度検知分解能よりも小さな温度差を正確に検知することはできない。従って、定着ローラ内外に配設した各々の温度検知分解能Ｔｓｔｅｐの加算値以上の温度差しか検知することができない。よって所定の温度差Ｔｎと温度検知分解能Ｔｓｔｅｐの関係をＴｎ≧２Ｔｓｔｅｐと定めた。なお、今回は温度検知手段の温度検知分解能は、測定温度に±４％の温度検知分解能をもっている。すなわち、定着ローラの温調温度Ｔｔ＝２００℃を±８℃の精度をもって検知することができる。そのため、内外に設けた二つの温度検知手段による検知分解能は１６℃となるため、所定の温度差をそれよりも大きな２０［ｄｅｇ］と定め、温度検知手段による誤検知を伴わない制御手段とした。
【００３０】
また、本実施例では温度検知手段１１，１２は定着ローラ１に接することで温度検知していたが、非接触にて検知してもよい。この場合、サーミスタ１１にトナーや紙片といった異物が付着することによる誤検知が防止でき、さらに定着ローラの表面削れ、傷など防止することができ定着ローラの耐久性が向上される。また、組立ての際には、サーミスタ１２と定着ローラ１との接触を回避することができるため、サービス性の向上が実現される。
【００３１】
また、本実施例では異常と判断する内外面温度差Ｔｎは常に一定であったが、加熱開始からの時間に応じて変えても良い。すなわち加熱開始時ではローラの温度差は大きい傾向にあるのでＴｎは大きく設定し、所定温調温度に達したらローラ内外面温度差は小さい傾向になるので、所定温調温度時にはＴｎを小さく設定すれば、状況に応じたより適切な異常検知が行うことができる。
【００３２】
なお、温度検知手段の配置構成は、定着ローラ円周方向については、本実施例では、図示はしていないが、温度検知手段を定着ローラと磁束発生手段の対向する位置近傍の円周位置に配置した。こうすることで定着ローラの発熱領域温度を検知することができるため、定着ローラ外周面の性状変化による定着ローラの異常昇温を短時間で検知することが可能となる。
【００３３】
また、本実施例は温度検知手段の配置構成について定着ローラ円周方向についてのみ言及したが、同温度検知手段が定着ローラ長手方向の如何なる位置に配置されても本発明の効果は損なわれることはない。
【００３４】
【発明の効果】
以上に説明したように本発明によれば、誘導発熱体の外面及び内面に温度検知手段を略対向に配設したので、各々の温度検知手段の検知温度、ないし誘導発熱体の温度差に基づいて異常検知でき、定着ローラの温度状態に依存することなく、定着ローラの異常温度をいち早く検知し、装置停止や定着装置の動作制限することができるため、装置停止などによるダウンタイムを短縮することが可能となった。
【図面の簡単な説明】
【図１】本発明の定着装置の概略図
【図２】第一または第二の温度検知手段による温度上昇波形図
【図３】内外面温度差により過昇温防止を示した温度上昇波形図
【図４】従来の定着装置の概略図
【図５】従来の定着装置の概略図
【符号の説明】
Ｈ 記録材搬送路
Ｎ ニップ部
Ｓ 記録材
１ 定着ローラ
４ 磁束発生手段
５ 磁性コイル
６ 磁性体コア
８ 加圧ローラ
９ 温調制御手段
１０ 分離爪
１１ サーミスタ（第２の温度検知手段）
１２ サーミスタ（第１の温度検知手段）
１０１ 定着ローラ
１０８ 加圧ローラ
１１０ 分離爪
１１１ サーミスタ
１３１ サーモスイッチ
１４４ ハロゲンヒータ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic induction type fixing device used mainly in an image forming apparatus such as a copying machine or a printer that forms an image by an electrophotographic method.
[0002]
[Prior art]
FIG. 4 is an explanatory view of a conventional typical fixing device. In the fixing device, a fixing roller 101 having a heat source such as a halogen heater 144 and the like and a pressure roller 108 that is in pressure contact therewith to form a fixing nip portion are disposed.
[0003]
The temperature of the fixing roller 101 is detected by a
[0004]
Here, the temperature to be actually controlled is the temperature at the fixing nip N between the fixing roller 101 and the pressure roller 108. However, the surface temperature of the fixing nip N cannot be directly detected. Instead, the temperature of the fixing roller 101 other than the fixing nip is detected, and the temperature of the fixing nip of the fixing roller 101 is predicted and controlled.
[0005]
Further, the temperature of the fixing roller 101 may become abnormally high due to runaway due to a failure of the control unit or the like. A thermo switch 131 is provided on the surface of the fixing roller 101 as a power cut-off means at the time of abnormality in order to cut off the power to the heater in such an abnormality.
[0006]
The fixing roller 101 has a toner release layer (not shown) on the outer surface of the roller, and is composed of PTFE 10 to 50 μm or PFA 10 to 50 μm. In addition, a configuration in which a rubber layer is used inside the toner release layer is also known.
[0007]
A recording material S carrying a toner image electrostatically formed at a transfer portion (not shown) is conveyed to a fixing nip portion N from the direction of arrow C along a recording material conveyance path H (dashed line).
[0008]
Further, as shown in FIG. 5, it has a magnetic flux generating means 4 for generating a magnetic flux, and an induction heating element 1 (fixing roller) that generates electromagnetic induction heat by the action of the magnetic flux generated by the magnetic flux generating means. A fixing device using an induction heating method for heating an image has been proposed.
[0009]
In the case of an induction heating device, there has also been proposed a fixing device in which detection means for detecting the temperature of the fixing roller is provided on the inner surface of the fixing roller (see Patent Document 1).
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-108123
[Problems to be solved by the invention]
However, the above fixing device has the following problems.
[0012]
In the fixing device using the halogen lamp, a
[0013]
For this reason, if a foreign object (toner or a piece of paper) is caught between the fixing roller 101 and the temperature detecting means or if paper is wound around the fixing roller 101, the fixing roller and the temperature detecting means are not properly in contact with each other. Therefore, it is erroneously detected that the temperature of the fixing roller is lower than the actual temperature, and excessive power is supplied to the heater to further increase the temperature of the fixing roller. Therefore, the temperature of the fixing roller is excessively higher than the desired control temperature, and there is a risk of causing a nearby structural component to fail.
[0014]
Further, as in Patent Document 1, a fixing device that controls temperature by providing temperature detection means on the inner surface of an electromagnetic induction heating fixing roller has the following problems.
[0015]
The purpose of the temperature control of the fixing roller 101 is to appropriately control the outer peripheral surface temperature of the fixing roller 101. In this configuration, temperature detection means is provided on the inner surface of the fixing roller to control the temperature of the outer peripheral surface of the fixing roller.
[0016]
However, when the property of the outer peripheral surface of the fixing roller changes significantly due to adhesion of foreign matter on the outer peripheral surface of the fixing roller, the heat conduction state from the inner peripheral surface of the fixing roller to the outer peripheral surface changes. For this reason, it becomes difficult to accurately detect and control the appropriate temperature of the outer peripheral surface of the fixing roller by the temperature detecting means on the inner peripheral surface of the fixing roller. Therefore, the recording paper S may not be supplied with sufficient heat and may be accompanied by image defects such as insufficient fixing.
[0017]
Therefore, the present invention has been made in view of the above problems.
[0018]
The purpose is to prevent the fixing roller temperature from suddenly becoming abnormal due to foreign matter (toner or paper piece) being caught between the fixing roller and the temperature detecting means, and at the same time, the surface property of the fixing roller is suddenly changed. This is to prevent the occurrence of fixing failure due to a decrease in the temperature of the outer peripheral surface of the fixing roller even if it changes.
[0019]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention
Magnetic flux generating means for generating magnetic flux when energized,
Energizing means for energizing the magnetic flux generating means;
An induction heating element that generates electromagnetic induction heat by the action of magnetic flux generated by the magnetic flux generation means;
Temperature detecting means for detecting the temperature of the induction heating element;
Control means for controlling the energization amount of the energization means based on the detected temperature of the temperature detection means;
A fixing device for fixing toner to a transfer material by heat of the induction heating element,
The temperature detection means includes first temperature detection means for detecting the temperature of the inner surface of the induction heating element;
Providing a second temperature detecting means for detecting the temperature of the outer surface of the induction heating element;
The control means solves the problem by detecting an abnormality based on the temperature information obtained by the first temperature detection means and the second temperature detection means.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
(Example 1)
Hereinafter, an embodiment of the present invention will be described with reference to FIG.
[0021]
FIG. 1 is a schematic cross-sectional view of an induction heating fixing unit which is a main component of the present embodiment. The same elements as those in FIG.
[0022]
Reference numeral 1 denotes a fixing roller formed of a high permeability member such as iron in a hollow cylindrical shape, and is formed into a thin wall having a thickness of 1 mm or less. Reference numeral 4 denotes magnetic flux generating means, which is composed of a ferrite core 6 as a magnetic flux control core material and a conductive coil 5 wound around the ferrite core. Reference numeral 11 denotes a thermistor which is an outer surface temperature detecting means (second temperature detecting means) installed so as to measure the temperature in contact with the outer periphery of the fixing roller 1. A thermistor 12 is an inner surface temperature detecting means (first temperature detecting means) provided substantially opposite to the thermistor 11 across the fixing roller 1. By providing the thermistor at a substantially opposite position across the fixing roller in this way, it is possible to detect the temperature of the inner peripheral surface and the outer peripheral surface of the fixing roller without affecting the temperature unevenness in the circumferential direction of the fixing roller. The temperature difference between the inner peripheral surface and the outer peripheral surface of the fixing roller can be detected more accurately at an arbitrary position on the circumference, and appropriate temperature control of the fixing roller can be performed. However, even if the outer surface temperature detection means 11 and the inner surface temperature detection means 12 are not necessarily opposed to each other, for example, the installation position A of the outer surface temperature detection means 11 with respect to the fixing roller 1 and the installation position of the inner surface temperature detection means 12 with respect to the fixing roller 1. Assuming B, the output result of the inner and outer surface temperature detecting means is compared by shifting the arc AB by the time calculated by dividing the rotation speed of the fixing roller 1, thereby affecting the temperature unevenness in the circumferential direction of the fixing roller. It is also possible to detect the temperatures of the inner and outer peripheral surfaces of the fixing roller without any problem.
[0023]
Reference numeral 9 denotes a temperature control unit (control means) including the following excessive temperature rise prevention unit (not shown) and a temperature adjustment unit (not shown). That is, the detected temperature Tout corresponding to the output of the outer surface temperature detecting means is compared with the reference temperature T1,
Tout ≧ T1
At this time, the first overheating prevention comparison unit (not shown) that outputs a drive stop signal (STOP) to an excitation power source (not shown) and the detected temperature Tin corresponding to the output of the inner surface temperature detecting means and the reference temperature T2 are compared. And
Tin ≧ T2
At this time, a second overheating prevention comparator (not shown) that outputs a drive stop signal (STOP) to an excitation power supply (not shown), a detection temperature Tout of the outer surface temperature detection means, and a detection temperature Tin of the inner surface temperature detection means Compare the temperature difference ΔT (= Tin−Tout) with the reference temperature Tn,
ΔT ≧ Tn
A third overheating prevention comparator (not shown) that outputs a drive stop signal (STOP) to an excitation power source (not shown) at the time, and further compares the output Tout of the outer surface temperature detecting means with the reference temperature Tt. Thus, a temperature adjustment unit (not shown) that outputs a control signal (POWER) to the power supply so as to minimize the difference is included.
[0024]
When the coil 5 is disposed on the inner surface of the fixing roller 1, the inner surface temperature is generally higher than the outer surface temperature, so that T2> T1.
It is set to become. Reference numeral 10 denotes a separation claw for preventing the sheet from being wound around the fixing roller 1.
[0025]
2 and 3 are temperature rise waveforms during standby and copying when the heating control is performed by the fixing device of this embodiment. The temperature transition is shown from the start of heating of the detected temperature Tout of the outer surface temperature detecting means and the detected temperature Tin of the inner surface temperature detecting means.
[0026]
The detected temperature of the thermistors 11 and 12 rises almost simultaneously by turning on the power while rotating the fixing roller 1 by a driving means (not shown). At the start of heating the fixing roller temperature, the maximum power is input to reduce the rise time. When the fixing roller temperature reaches Tt, Tout becomes Tout≈Tt.
An excitation power source (not shown) applies electric power in accordance with the output from the temperature adjustment unit as the control means. Thus, since the temperature of the fixing roller 1 is controlled not by the inner surface temperature of the fixing roller but by the outer surface temperature, the temperature outside the fixing roller 1 can be accurately controlled. However, when the temperature of the roller rises due to some abnormality during the heating, and the detected temperatures Tout and Tin of the thermistor 11 and the thermistor 12 reach the reference temperatures T1 and T2, an excessive temperature rise prevention comparison unit (not shown) is stopped. A signal is output and the excitation power supply stops operating. (X points of curves a to d in FIG. 2)
Further, as shown by the curves e to k in FIG. 3, the temperature difference between the inner and outer surfaces of the roller is observed, and when the temperature difference ΔT is larger than the predetermined temperature Tn, an excessive temperature rise prevention comparator (not shown) outputs a STOP signal. The excitation power supply stops operating.
[0027]
Curves e to k in FIG. 3 show a case where energization is stopped by determining that the temperature control is abnormal. (X point of ek curve in FIG. 3) For example, the sensitivity of the outer surface temperature detecting means 11 decreases due to adhesion of foreign matter on the fixing roller, and excessive power is applied to increase the outer peripheral temperature of the fixing roller. For example, when the temperature of the peripheral surface is abnormally increased and ΔT ≧ Tn [deg], or when either the inner surface or the outer surface temperature detecting means fails, ΔT ≧ Tn, and it is determined that there is an abnormality.
[0028]
As described above, according to the present invention, when an abnormality is determined by setting an upper limit value as shown in FIG. 2, the abnormality cannot be detected unless the roller temperature becomes high T 1 and T 2 , but as shown in FIG. Since the abnormality is detected by looking at the temperature difference between the inside and outside of the fixing roller, the abnormality can be detected quickly even when the roller temperature is low as shown by the curves e and f in FIG. Accordingly, since the operation restriction of the apparatus main body or the fixing apparatus can be applied more quickly, it is possible to reduce the downtime of the apparatus.
[0029]
The predetermined temperature difference Tn is limited by the temperature detection resolution Tstep of the outer surface temperature detection means 11 and the inner surface temperature detection means 12. When detecting the temperature difference of the fixing roller, a temperature difference smaller than the temperature detection resolution of the temperature detection means cannot be detected accurately. Therefore, it is not possible to detect a temperature difference that is equal to or greater than the added value of each temperature detection resolution Tstep disposed inside and outside the fixing roller. Therefore, the relationship between the predetermined temperature difference Tn and the temperature detection resolution Tstep is determined as Tn ≧ 2Tstep. Note that this time, the temperature detection resolution of the temperature detection means is ± 4% of the measurement temperature. That is, the temperature adjustment temperature Tt = 200 ° C. of the fixing roller can be detected with an accuracy of ± 8 ° C. Therefore, since the detection resolution by the two temperature detection means provided inside and outside is 16 ° C., the predetermined temperature difference is set to 20 [deg] larger than that, and the control means is not accompanied by erroneous detection by the temperature detection means. .
[0030]
Further, in this embodiment, the temperature detecting means 11 and 12 detect the temperature by contacting the fixing roller 1, but they may be detected in a non-contact manner. In this case, it is possible to prevent erroneous detection due to adhesion of foreign matter such as toner or paper pieces to the thermistor 11, and further to prevent the surface of the fixing roller from being scraped or scratched, thereby improving the durability of the fixing roller. Further, when assembling, the contact between the thermistor 12 and the fixing roller 1 can be avoided, so that the serviceability is improved.
[0031]
In this embodiment, the inner / outer surface temperature difference Tn determined as abnormal is always constant, but may be changed according to the time from the start of heating. That is, since the roller temperature difference tends to be large at the start of heating, Tn is set large, and when the temperature reaches a predetermined temperature adjustment temperature, the temperature difference between the inner and outer surfaces of the roller tends to be small. Thus, more appropriate abnormality detection according to the situation can be performed.
[0032]
Although the arrangement of the temperature detection means is not shown in the present embodiment in the circumferential direction of the fixing roller, the temperature detection means is placed at a circumferential position in the vicinity of the position where the fixing roller and the magnetic flux generation means face each other. Arranged. By doing so, it is possible to detect the heat generation region temperature of the fixing roller, so that it is possible to detect an abnormal temperature increase of the fixing roller due to a change in the property of the outer peripheral surface of the fixing roller in a short time.
[0033]
In this embodiment, the arrangement of the temperature detection means is described only in the circumferential direction of the fixing roller. However, the effect of the present invention is not impaired regardless of the position of the temperature detection means in the longitudinal direction of the fixing roller. Absent.
[0034]
【The invention's effect】
As described above, according to the present invention, since the temperature detecting means is disposed substantially opposite to the outer surface and the inner surface of the induction heating element, it is based on the detected temperature of each temperature detection means or the temperature difference between the induction heating elements. It is possible to detect abnormalities and to detect the abnormal temperature of the fixing roller quickly without depending on the temperature state of the fixing roller, and to stop the device and limit the operation of the fixing device. Became possible.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a fixing device of the present invention. FIG. 2 is a temperature rise waveform diagram by first or second temperature detecting means. FIG. FIG. 4 is a schematic diagram of a conventional fixing device. FIG. 5 is a schematic diagram of a conventional fixing device.
H Recording material conveyance path N Nip portion S Recording material 1 Fixing roller 4 Magnetic flux generating means 5 Magnetic coil 6 Magnetic core 8 Pressure roller 9 Temperature control means 10 Separation claw 11 Thermistor (second temperature detection means)
12 Thermistor (first temperature detection means)
101 Fixing roller 108 Pressure roller 110
Claims (6)
前記磁束発生手段に通電する通電手段と、
前記磁束発生手段が発生する磁束の作用により電磁誘導発熱する誘導発熱体と、
前記誘導発熱体の温度を検知する温度検知手段と、
前記温度検知手段の検知温度に基き、前記通電手段の通電する通電量を制御する制御手段と、
を有し、前記誘導発熱体の熱により転写材にトナーを定着する定着装置であって、
前記温度検知手段は、前記誘導発熱体の内面の温度を検知する第１の温度検知手段と、
前記誘導発熱体の外面の温度を検知する第２の温度検知手段とを設け、
前記制御手段は前記第１の温度検知手段と前記第２の温度検知手段で得られた温度情報に基いて異常検知することを特徴とする定着装置。Magnetic flux generating means for generating magnetic flux when energized,
Energizing means for energizing the magnetic flux generating means;
An induction heating element that generates electromagnetic induction heat by the action of magnetic flux generated by the magnetic flux generation means;
Temperature detecting means for detecting the temperature of the induction heating element;
Control means for controlling the energization amount of the energization means based on the detected temperature of the temperature detection means;
A fixing device for fixing toner to a transfer material by heat of the induction heating element,
The temperature detection means includes first temperature detection means for detecting the temperature of the inner surface of the induction heating element;
Providing a second temperature detecting means for detecting the temperature of the outer surface of the induction heating element;
The fixing device is characterized in that the control means detects an abnormality based on temperature information obtained by the first temperature detection means and the second temperature detection means.
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| JP2003202982A JP4262010B2 (en) | 2003-07-29 | 2003-07-29 | Fixing device |
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| JP2003202982A JP4262010B2 (en) | 2003-07-29 | 2003-07-29 | Fixing device |
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| JP4262010B2 JP4262010B2 (en) | 2009-05-13 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006259733A (en) * | 2005-03-17 | 2006-09-28 | Toshiba Corp | Fixing apparatus and heating apparatus control method |
| JP2008009183A (en) * | 2006-06-29 | 2008-01-17 | Matsushita Electric Ind Co Ltd | Fixing device, image forming apparatus using the same and abnormality decision method |
| JP2018013420A (en) * | 2016-07-21 | 2018-01-25 | 株式会社リコー | Temperature detection sensor abnormality determination device, heating device, image forming system, and detected temperature abnormality determination method |
| JP2018159824A (en) * | 2017-03-23 | 2018-10-11 | キヤノン株式会社 | Image forming apparatus |
| JP2020112623A (en) * | 2019-01-09 | 2020-07-27 | コニカミノルタ株式会社 | Fixing device, image forming apparatus, control method, and computer program |
-
2003
- 2003-07-29 JP JP2003202982A patent/JP4262010B2/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006259733A (en) * | 2005-03-17 | 2006-09-28 | Toshiba Corp | Fixing apparatus and heating apparatus control method |
| JP2008009183A (en) * | 2006-06-29 | 2008-01-17 | Matsushita Electric Ind Co Ltd | Fixing device, image forming apparatus using the same and abnormality decision method |
| JP2018013420A (en) * | 2016-07-21 | 2018-01-25 | 株式会社リコー | Temperature detection sensor abnormality determination device, heating device, image forming system, and detected temperature abnormality determination method |
| JP2018159824A (en) * | 2017-03-23 | 2018-10-11 | キヤノン株式会社 | Image forming apparatus |
| JP6991727B2 (en) | 2017-03-23 | 2022-01-12 | キヤノン株式会社 | Image forming device |
| JP2020112623A (en) * | 2019-01-09 | 2020-07-27 | コニカミノルタ株式会社 | Fixing device, image forming apparatus, control method, and computer program |
| JP7290027B2 (en) | 2019-01-09 | 2023-06-13 | コニカミノルタ株式会社 | FIXING DEVICE, IMAGE FORMING APPARATUS, CONTROL METHOD, AND COMPUTER PROGRAM |
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| JP4262010B2 (en) | 2009-05-13 |
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