JP4208772B2 - Fixing device and heater used in the fixing device - Google Patents

Fixing device and heater used in the fixing device Download PDF

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JP4208772B2
JP4208772B2 JP2004182418A JP2004182418A JP4208772B2 JP 4208772 B2 JP4208772 B2 JP 4208772B2 JP 2004182418 A JP2004182418 A JP 2004182418A JP 2004182418 A JP2004182418 A JP 2004182418A JP 4208772 B2 JP4208772 B2 JP 4208772B2
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power supply
heating
heat generation
heater
supply circuit
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JP2006004860A5 (en
JP2006004860A (en
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岩崎  敦志
加藤  明
朋之 牧平
宏明 酒井
洋 高見
前田  雅文
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Canon Inc
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Canon Inc
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Priority to CN2009101718808A priority patent/CN101692161B/en
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本発明は、電子写真複写機や電子写真プリンタ等の画像形成装置に搭載される定着装置、及びその定着装置に用いられるヒータに関するThe present invention is a fixing device mounted on an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer, and to a heater for use in the fixing device.

電子写真複写機や電子写真プリンタに搭載される定着装置における加熱方式として、フィルム加熱方式が提案され(特許文献1)、実用化されている。 As heating system definitive the constant wearing location to be mounted on an electrophotographic copying machine or an electrophotographic printer, a film heating type is proposed (Patent Document 1), it has been put to practical use.

このフィルム加熱方式は、加熱体に加熱用回転体である耐熱性の薄膜フィルム(定着フィルム)を加圧部材としての加圧用回転体(弾性ローラ)で密着させて摺動搬送させ、この定着フィルムを挟んで加熱体と加圧用回転体とで形成される圧接ニップ部に未定着画像を担持した記録材としての被加熱材を導入して定着フィルムと一緒に搬送させて、定着フィルムを介して付与される加熱体からの熱と圧接ニップ部の加圧力によって未定着画像を転写材上に加熱定着させるものである。 In this film heating method, a heat-resistant thin film (fixing film), which is a heating rotator, is brought into close contact with a heating rotator (elastic roller) as a pressure member, and is slid and conveyed. A material to be heated as a recording material carrying an unfixed image is introduced into a pressure nip formed by a heating body and a pressure rotating body across the sheet and conveyed together with the fixing film, The unfixed image is heated and fixed on the transfer material by the heat applied from the heating member and the pressure applied at the pressure nip.

このフィルム加熱方式の定着装置は、定着装置全体を低熱容量部材で構成することができるため、省電力化・ウェイトタイム短縮化(クイックスタート性)が可能である。   In this film heating type fixing device, since the entire fixing device can be constituted by a low heat capacity member, it is possible to save power and shorten the wait time (quick start property).

例えば加熱体としては、アルミナ(Al)や窒化アルミニウム(AlN)等、低熱容量の板状セラミック基材をベースとし、その一面に銀パラジウム(Ag/Pd)・TaN等を用いた発熱パターン、および前記発熱パターンに通電させるためのAg等の低抵抗材材料よりなる給電電極パターンをスクリーン印刷等で形成具備させ、さらに前記発熱パターン形成面を薄肉ガラス保護層で覆ってなるものである。 For example, the heating body is based on a plate-shaped ceramic substrate with a low heat capacity such as alumina (Al 2 O 3 ) or aluminum nitride (AlN), and silver palladium (Ag / Pd) · Ta 2 N is used on one side. A heat generating pattern, and a power supply electrode pattern made of a low-resistance material such as Ag for energizing the heat generating pattern is formed by screen printing or the like, and the heat generating pattern forming surface is covered with a thin glass protective layer It is.

この加熱体は、給電電極パターンを介して発熱パターンに通電がなされることにより発熱し、加熱体全体が急速昇温する。この加熱体の昇温を、加熱体に当接あるいは近傍に配置された温度検知手段としてのサーミスタにより検知し、通電駆動制御部へフィードバックされる。通電制御部はサーミスタで検知される加熱体温度が所定のほぼ一定温度(定着温度)に維持されるように発熱パターンに対する通電を制御する。すなわち加熱体は所定の定着温度に加熱制御される。   This heating body generates heat by energizing the heating pattern through the power supply electrode pattern, and the entire heating body rapidly rises in temperature. This temperature rise of the heating body is detected by a thermistor as temperature detection means disposed in contact with or near the heating body and fed back to the energization drive control unit. The energization control unit controls energization of the heat generation pattern so that the temperature of the heating body detected by the thermistor is maintained at a predetermined substantially constant temperature (fixing temperature). That is, the heating body is controlled to be heated to a predetermined fixing temperature.

この種の定着装置は、低熱容量であることによりクイックスタート性に優れている反面、低熱容量であるがゆえの問題を有している。被加熱材の長手方向長さが加熱体の長手方向長さに対して比較的狭い場合、ニップ部において被加熱材が通る通紙部と通らない非通紙部とでは、加熱体から奪われる熱量が大きく異なり、従って、被加熱材に熱量が奪われない非通紙部の温度は通紙していくにしたがって徐々に上昇していく、いわゆる非通紙部昇温現象を生じやすく、低熱容量であるフィルム加熱方式においては一層厳しくなる。過度の非通紙部昇温は定着装置の構成部材を熱損させて装置寿命を低下させる等の弊害を生じさせるため、これを解決するための加熱体構成および定着装置の制御方法が提案されている。   This type of fixing device is excellent in quick start due to its low heat capacity, but has a problem due to its low heat capacity. When the longitudinal direction length of the heated material is relatively narrow with respect to the longitudinal length of the heated body, the heated body is deprived of the sheet passing portion through which the heated material passes and the non-sheet passing portion that does not pass through the nip portion. The amount of heat differs greatly. Therefore, the temperature of the non-sheet passing portion where the amount of heat is not taken away by the heated material gradually increases as the sheet passes, so that a so-called non-sheet passing portion temperature rise phenomenon is likely to occur and the temperature is low. The film heating method, which is a heat capacity, becomes more severe. Excessive temperature rise in the non-sheet-passing section causes problems such as heat loss of the components of the fixing device and shortening the life of the device. Therefore, a heating element configuration and a fixing device control method for solving this problem have been proposed. ing.

特許文献2には、図12(a)に示すような構成の加熱体700を用いて、上記非通紙部昇温を低減させる方法が提案されている。図13(a)に加熱体駆動回路70を示す。   Patent Document 2 proposes a method of reducing the temperature rise of the non-sheet passing portion by using a heating body 700 having a configuration as shown in FIG. FIG. 13A shows the heating element driving circuit 70.

図12(a)の加熱体700は、セラミック基材704の長手方向において発熱領域が異なる複数の発熱パターン701a・701bを有し、それぞれの発熱パターンが独立に通電され得る給電電極702a・702b、共通電極703を有する加熱体である。   The heating body 700 in FIG. 12A has a plurality of heat generation patterns 701a and 701b having different heat generation regions in the longitudinal direction of the ceramic substrate 704, and the heat generation patterns 701a and 702b that can be independently energized. It is a heating body having a common electrode 703.

図13(a)の加熱体駆動回路70は、前記加熱体700の通電制御をつかさどる駆動回路の概略一例である。加熱体700にサーミスタ50が当接あるいはその近傍に配置され、加熱体700の温度検知結果をCPU71に出力している。CPU71はサーミスタ50の温度検知結果に基づいて所望の温度制御をするべくトライアック72a・72bの点灯タイミングを駆動制御する。ここでCPU71は、トライアック72a・72bの点灯比率を決定でき、所望の発熱比率をもって上記温度制御を施すことができる。また、加熱体700の過昇温を防止する安全素子60(温度ヒューズ、サーモスイッチ等)が通電ライン上に直列接続され、加熱体700に当接あるいはその近傍に配置されることにより、加熱体700の熱暴走時に前記安全素子60を作動させて加熱体700への通電を遮断できるように構成されている。   A heating body drive circuit 70 in FIG. 13A is a schematic example of a drive circuit that controls energization control of the heating body 700. The thermistor 50 is placed in contact with or near the heating body 700, and the temperature detection result of the heating body 700 is output to the CPU 71. The CPU 71 drives and controls the lighting timings of the triacs 72a and 72b to perform desired temperature control based on the temperature detection result of the thermistor 50. Here, the CPU 71 can determine the lighting ratio of the triacs 72a and 72b, and can perform the temperature control with a desired heat generation ratio. In addition, a safety element 60 (temperature fuse, thermo switch, etc.) for preventing overheating of the heating body 700 is connected in series on the energization line, and is in contact with the heating body 700 or disposed in the vicinity thereof. When the thermal runaway of 700, the safety element 60 is operated to cut off the energization to the heating body 700.

図12(a)の加熱体700を具備した、通紙基準が長手中央である定着装置を用いると、例えば長手方向長さが比較的大きい被加熱材(以下、大サイズ紙という)を定着させる場合には電極702b・703間に通電させて発熱パターン701bを発熱させ、長手方向長さが比較的小さい被加熱材(以下、小サイズ紙という)を定着させる場合には電極702a・703間に通電させて発熱パターン701aを発熱させることによって上記非通紙部昇温を低減することが可能となる。   When a fixing device including the heating body 700 of FIG. 12A and having a sheet passing reference centered in the longitudinal direction is used, for example, a heated material having a relatively long longitudinal length (hereinafter referred to as large size paper) is fixed. In this case, electricity is applied between the electrodes 702b and 703 to cause the heat generation pattern 701b to generate heat, and when a heated material having a relatively small length in the longitudinal direction (hereinafter referred to as a small size paper) is fixed, the electrodes 702a and 703 are By energizing the heat generating pattern 701a to generate heat, it is possible to reduce the temperature rise of the non-sheet passing portion.

特許文献3には、同様の加熱体構成として、図12(b)に示すような3本の発熱パターンをそれぞれ独立に通電駆動する方式の加熱体も提案されている。この場合、加熱体800は、セラミック基材804面上に、発熱パターン801a・801b・801c、給電電極802a・802b・802c、共通電極803を有し、加熱体800を図13(b)に示す加熱体駆動回路75によって駆動制御させることにより、それぞれの発熱パターンは独立に通電駆動され得る。   Patent Document 3 also proposes a heating body of a type in which three heating patterns as shown in FIG. 12B are individually energized and driven as a similar heating body configuration. In this case, the heating body 800 has heating patterns 801a, 801b, 801c, power supply electrodes 802a, 802b, 802c, and a common electrode 803 on the surface of the ceramic substrate 804, and the heating body 800 is shown in FIG. By performing drive control by the heating element drive circuit 75, each heat generation pattern can be independently energized and driven.

特許文献4には、更に、種々の紙サイズに応じて多段階的な発熱制御をおこなうことにより、定着性を確保しながら非通紙部昇温を一定の範囲内に抑えることが可能な円弧型発熱分布を形成しうる加熱体を用いた定着装置も提案されている。   Patent Document 4 further discloses an arc that can suppress non-sheet passing portion temperature rise within a certain range while ensuring fixability by performing multi-step heat generation control according to various paper sizes. A fixing device using a heating body capable of forming a mold heat generation distribution has also been proposed.

図12(c)の加熱体900は、セラミック基材904の長手方向において発熱分布が異なる複数の発熱パターン901a・901bを有し、それぞれの発熱パターンが独立に通電され得る給電電極902a・902b、共通電極903を有する加熱体である。そして発熱体パターン901aは、長手中央付近から端部にかけて多段階的に発熱パターン幅を広げることによって単位長さ当りの抵抗値を小さくし、通電させた場合に長手中央を発熱ピークとする山型発熱分布をなし、発熱体パターン901bは、長手中央から端部にかけて発熱パターン幅を狭めることによって単位長さ当りの抵抗値を大きくし、通電させた場合に長手中央を発熱ボトムとする谷型発熱分布をなすように形成されている。   A heating body 900 in FIG. 12C includes a plurality of heat generation patterns 901a and 901b having different heat generation distributions in the longitudinal direction of the ceramic base 904, and the heat generation patterns 901a and 902b that can be independently energized. This is a heating body having a common electrode 903. The heating element pattern 901a has a mountain shape in which the resistance value per unit length is reduced by enlarging the heating pattern width in multiple steps from the vicinity of the longitudinal center to the end portion, and the longitudinal center is a heating peak when energized. The heating element pattern 901b has a heat generation distribution, the resistance value per unit length is increased by narrowing the heating pattern width from the longitudinal center to the end, and when it is energized, a valley-shaped heating with the longitudinal center as the heating bottom It is formed to have a distribution.

加熱体900を図13(a)の加熱体駆動回路70に組み込み、CPU71でトライアック72a・72bの点灯比率を決定して駆動制御させることにより、加熱体900の長手発熱分布に円滑な勾配を持たせることが可能となる。この加熱体900を具備した、通紙基準が中央基準である定着装置を用いた場合、例えば被加熱材の長手方向長さに応じてトライアック72aと72bの点灯比率10:10〜10:0のいずれかを選択させることにより、非通紙部昇温と定着性をより厳密に両立させることが可能となる。
特開昭63−313182号公報 特開2000−162909号公報 特開2000−250337号公報 特開平10−177319号公報
The heating element 900 is incorporated in the heating element driving circuit 70 of FIG. 13A, and the CPU 71 determines the lighting ratio of the triacs 72a and 72b to control the driving, thereby providing a smooth gradient in the longitudinal heat generation distribution of the heating element 900. It becomes possible to make it. In the case of using the fixing device having the heating body 900 and the paper passing reference being the central reference, for example, the lighting ratio of the triacs 72a and 72b is 10:10 to 10: 0 according to the longitudinal length of the heated material. By selecting one of them, it is possible to more strictly satisfy the temperature rise of the non-sheet passing portion and the fixing property.
JP-A-63-313182 JP 2000-162909 A JP 2000-250337 A Japanese Patent Laid-Open No. 10-177319

しかしながら、従来のセラミック加熱体を用いたフィルム加熱方式の定着装置においては、例えば定着装置内のトライアックが故障した場合など、いわゆる定着装置の暴走によって加熱体が過昇温し、加熱体に当接される安全素子(温度ヒューズ、サーモスイッチ)が作動する以前に加熱体に加わる熱ストレスによってセラミック基材が割れてしまう可能性があった。セラミック基材の割れ方によっては、発熱パターンを含む抵抗回路側(一次)と加熱体の温度検知をつかさどる温度検知素子側(二次)回路との間の絶縁耐圧を満足することができなくなり、上記定着装置を具備する画像形成装置本体に漏れた電流によって二次系回路を破壊する可能性があった。   However, in a conventional film heating type fixing device using a ceramic heating body, for example, when the triac in the fixing device breaks down, the heating body overheats due to a so-called runaway of the fixing device and comes into contact with the heating body. There is a possibility that the ceramic base material is broken by the thermal stress applied to the heating body before the safety element (thermal fuse, thermo switch) to be operated is activated. Depending on how the ceramic substrate is cracked, it will not be possible to satisfy the withstand voltage between the resistance circuit side (primary) including the heat generation pattern and the temperature detection element side (secondary) circuit that controls the temperature detection of the heating element. There is a possibility that the secondary circuit is destroyed by the current leaked to the image forming apparatus main body having the fixing device.

基材の一断面に加わる熱ストレスσは、基材の一断面内の温度分布が対称の場合、基材の線膨張係数εとヤング率E、基材内の温度差ΔTとして下式のように示される。ΔTは基材の熱伝導率に依存する。   When the temperature distribution in one cross section of the base material is symmetrical, the thermal stress σ applied to one cross section of the base material is expressed by the following equation as the linear expansion coefficient ε and Young's modulus E of the base material and the temperature difference ΔT in the base material: Shown in ΔT depends on the thermal conductivity of the substrate.

σ=ε・E・ΔT
しかし、温度分布が非対称である場合には、基材に対する曲げモーメントが加わるために温度差ΔTに単純比例しなくなり、一般的に基材のたわみ側の引張りストレスが大きくなる傾向がある。この引張りストレスが基材の曲げ強度(破断強度)を超えると破損に至る。
σ = ε · E · ΔT
However, when the temperature distribution is asymmetric, a bending moment is applied to the base material, so that it is not simply proportional to the temperature difference ΔT, and generally there is a tendency for tensile stress on the deflection side of the base material to increase. If this tensile stress exceeds the bending strength (breaking strength) of the base material, it will be damaged.

例えば、基板長さ370mm、基板幅10mm、基板厚1mmのアルミナ基材の一面に、長さ方向に沿って発熱パターンを形成した加熱体の場合、最も大きな熱ストレスが加わるのが基板幅方向断面であることが知られている。したがって、熱ストレスによる加熱体破損は、基板幅方向の温度分布に大きく依存すると考えてよい。   For example, in the case of a heating body in which a heat generation pattern is formed along the length direction on one surface of an alumina base material having a substrate length of 370 mm, a substrate width of 10 mm, and a substrate thickness of 1 mm, the largest thermal stress is applied to the cross section in the substrate width direction. It is known that Therefore, it may be considered that the heating element breakage due to thermal stress largely depends on the temperature distribution in the substrate width direction.

ここで、従来における複数ドライブ加熱体、すなわち複数のトライアックで複数の発熱パターンを独立に通電発熱させる加熱体においては、1つのトライアックが故障して加熱体が熱暴走した場合、基板幅方向断面の温度分布の非対称度が大きくなり、それに伴って前記引張りストレスが強く作用していたため、加熱体の破損に対するマージンが少なかった。   Here, in a conventional multiple drive heating element, that is, a heating element in which a plurality of heat generation patterns are independently energized and heated by a plurality of triacs, if one of the triacs fails and the heating element runs out of heat, Since the degree of asymmetry of the temperature distribution was increased and the tensile stress was acting strongly along with this, the margin for damage to the heating element was small.

例えば、図12(a)の加熱体700では、基板の幅方向(短手方向)の略中央(以下基板短手方向略中央と記す)Cに対して発熱パターン701aが非対称な領域に形成されているために、図13(a)におけるトライアック72aの故障時において基板幅方向断面の温度分布の非対称度が大きくなり、前記破損マージンが少なかった。   For example, in the heating body 700 of FIG. 12A, the heat generation pattern 701a is formed in an asymmetric region with respect to the approximate center (hereinafter referred to as the approximate center of the substrate short direction) C in the width direction (short direction) of the substrate. For this reason, when the triac 72a in FIG. 13A failed, the degree of asymmetry of the temperature distribution in the cross section in the substrate width direction increased, and the damage margin was small.

図12(b)の加熱体800では、発熱パターン全体の構成としては基板短手方向略中央Cに対して対称な領域に形成されているものの、個々の発熱パターンが独立駆動され得る構成のために、図13(b)におけるトライアック77aもしくはトライアック77cのうちいずれか1つの故障時において、前記温度分布の非対称度が大きくなり、前記破損マージンが少なかった。   In the heating element 800 of FIG. 12B, although the entire heat generation pattern is formed in a region symmetric with respect to the substantially center C in the lateral direction of the substrate, the individual heat generation patterns can be driven independently. In addition, when any one of the triacs 77a and 77c in FIG. 13B fails, the degree of asymmetry of the temperature distribution increases and the damage margin is small.

図12(c)の加熱体900においても同様に、発熱パターン全体の構成としては基板短手方向略中央Cに対して略対称な領域に形成されているものの、個々の発熱パターン901a・901bのいずれか1つの熱暴走により非対称度が大きくなり、前記破損マージンが少なかった。   Similarly, in the heating element 900 of FIG. 12C, the entire heat generation pattern is formed in a region that is substantially symmetric with respect to the substantially center C in the lateral direction of the substrate, but each of the heat generation patterns 901a and 901b has the same structure. Any one thermal runaway increased the degree of asymmetry, and the damage margin was small.

本発明は、ヒータに設けられる3本の発熱抵抗体のうち中央の1本の発熱抵抗体を、ヒータの長手方向中央部から両端部に向かって長手方向の単位長さあたりの抵抗値が徐々に小さくなる抵抗値分布のものとする場合よりも、基板が折れるまでの時間を稼ぐことが可能な定着装置、及びその定着装置に用いられるヒータに関する。 According to the present invention, the resistance value per unit length in the longitudinal direction of one heating resistor in the center of the three heating resistors provided in the heater is gradually increased from the longitudinal center portion of the heater toward both ends. The present invention relates to a fixing device and a heater used in the fixing device, which can increase the time until the substrate is bent, compared to a case where the resistance value distribution becomes smaller.

本発明に係る定着装置、及びその定着装置に用いられるヒータの構成は以下のとおりである。 The configuration of the fixing device according to the present invention and the heater used in the fixing device are as follows.

筒状の定着フィルムと、セラミック基板と前記セラミック基板上に設けられた発熱抵抗体とを有し前記定着フィルムの内面に接触するヒータと、前記定着フィルムを介して前記ヒータと共にトナー像を担持する記録材を挟持搬送する定着ニップ部を形成する加圧部材と、商用電源から前記発熱抵抗体へ供給する電力を制御する制御手段と、商用電源から前記発熱抵抗体への電力供給回路に設けられており前記ヒータの異常昇温により作動して前記電力供給回路を遮断する安全素子と、を有し、前記セラミック基板上には前記セラミック基板の短手方向の中央に1本、前記中央を基準にして対称な位置関係で2本、合計3本の発熱抵抗体が設けられており、前記基準に対して対称の位置関係にある2本の発熱抵抗体は常に同時に発熱するように一対の電極間に直列または並列に接続されており、商用電源から前記対称な位置関係の2本の発熱抵抗体への電力供給回路には前記制御手段からの信号に応じて電力供給回路を導通状態と遮断状態に切り換える第1の駆動素子が設けられており、商用電源から前記中央の1本の発熱抵抗体への電力供給回路には前記制御手段からの信号に応じて電力供給回路を導通状態と遮断状態に切り換える第2の駆動素子が設けられている定着装置において、前記対称な位置関係の2本の発熱抵抗体は、前記ヒータの長手方向中央部から両端部に向かって前記長手方向の単位長さあたりの抵抗値が徐々に小さくなる抵抗値分布となっており、前記中央の1本の発熱抵抗体は、前記ヒータの長手方向中央部から両端部に向かって前記長手方向の単位長さあたりの抵抗値が徐々に大きくなる抵抗値分布となっていることを特徴とする。A heater having a cylindrical fixing film, a ceramic substrate and a heating resistor provided on the ceramic substrate, and contacting the inner surface of the fixing film, and carrying a toner image together with the heater via the fixing film A pressure member that forms a fixing nip for nipping and conveying the recording material; a control unit that controls power supplied from a commercial power source to the heating resistor; and a power supply circuit from a commercial power source to the heating resistor. And a safety element that operates due to an abnormal temperature rise of the heater and shuts off the power supply circuit. One on the ceramic substrate in the short direction center of the ceramic substrate and the center as a reference In total, three heating resistors are provided in a symmetrical positional relationship, and the two heating resistors in a symmetrical positional relationship with respect to the reference always generate heat at the same time. The power supply circuit is connected in series or in parallel between the pair of electrodes, and the power supply circuit from the commercial power supply to the two heating resistors having the symmetrical positional relationship is electrically connected according to the signal from the control means. A first drive element that switches between a state and a cut-off state is provided, and the power supply circuit from the commercial power supply to the one heating resistor at the center is connected to the power supply circuit according to a signal from the control means In the fixing device provided with the second drive element that switches between the state and the cut-off state, the two heating resistors having the symmetrical positional relationship are arranged in the longitudinal direction from the center in the longitudinal direction of the heater toward both ends. The resistance value per unit length gradually decreases, and the central one heating resistor is a unit in the longitudinal direction from the central portion in the longitudinal direction of the heater toward both ends. Length Wherein the resistance value of becomes gradually larger resistance distribution.

筒状の定着フィルムと、セラミック基板と前記セラミック基板上に設けられた発熱抵抗体とを有し前記定着フィルムの内面に接触するヒータと、前記定着フィルムを介して前記ヒータと共にトナー像を担持する記録材を挟持搬送する定着ニップ部を形成する加圧部材と、商用電源から前記発熱抵抗体へ供給する電力を制御する制御手段と、商用電源から前記発熱抵抗体への電力供給回路に設けられており前記ヒータの異常昇温により作動して前記電力供給回路を遮断する安全素子と、を有し、前記セラミック基板上には前記セラミック基板の短手方向の中央に1本、前記中央を基準にして対称な位置関係で2本、合計3本の発熱抵抗体が設けられており、前記基準に対して対称の位置関係にある2本の発熱抵抗体は常に同時に発熱するように一対の電極間に直列または並列に接続されており、商用電源から前記対称な位置関係の2本の発熱抵抗体への電力供給回路には前記制御手段からの信号に応じて電力供給回路を導通状態と遮断状態に切り換える第1の駆動素子が設けられており、商用電源から前記中央の1本の発熱抵抗体への電力供給回路には前記制御手段からの信号に応じて電力供給回路を導通状態と遮断状態に切り換える第2の駆動素子が設けられている定着装置、に用いられるヒータにおいて、前記対称な位置関係の2本の発熱抵抗体は、前記ヒータの長手方向中央部から両端部に向かって前記長手方向の単位長さあたりの抵抗値が徐々に小さくなる抵抗値分布となっており、前記中央の1本の発熱抵抗体は、前記ヒータの長手方向中央部から両端部に向かって前記長手方向の単位長さあたりの抵抗値が徐々に大きくなる抵抗値分布となっていることを特徴とする。A heater having a cylindrical fixing film, a ceramic substrate and a heating resistor provided on the ceramic substrate, and contacting the inner surface of the fixing film, and carrying a toner image together with the heater via the fixing film A pressure member that forms a fixing nip for nipping and conveying the recording material; a control unit that controls power supplied from a commercial power source to the heating resistor; and a power supply circuit from a commercial power source to the heating resistor. And a safety element that operates due to an abnormal temperature rise of the heater and shuts off the power supply circuit. One on the ceramic substrate in the short direction center of the ceramic substrate and the center as a reference In total, three heating resistors are provided in a symmetrical positional relationship, and the two heating resistors in a symmetrical positional relationship with respect to the reference always generate heat at the same time. The power supply circuit is connected in series or in parallel between the pair of electrodes, and the power supply circuit from the commercial power supply to the two heating resistors having the symmetrical positional relationship is electrically connected according to the signal from the control means. A first drive element that switches between a state and a cut-off state is provided, and the power supply circuit from the commercial power supply to the one heating resistor at the center is connected to the power supply circuit according to a signal from the control means In the heater used in the fixing device provided with the second drive element that switches between the state and the cut-off state, the two heating resistors having the symmetrical positional relationship are arranged at both ends from the longitudinal center of the heater. The resistance value distribution per unit length in the longitudinal direction gradually decreases toward the end, and the one heating resistor at the center is directed from the longitudinal center of the heater toward both ends. The head Wherein the resistance value per unit length in the direction becomes gradually larger resistance distribution.

本発明によれば、ヒータに設けられる3本の発熱抵抗体のうち中央の1本の発熱抵抗体を、ヒータの長手方向中央部から両端部に向かって長手方向の単位長さあたりの抵抗値が徐々に小さくなる抵抗値分布のものとする場合よりも、基板が折れるまでの時間を稼ぐことが可能な定着装置、及びその定着装置に用いられるヒータを提供できる。 According to the present invention, among the three heating resistors provided in the heater, one central heating resistor is connected to the resistance value per unit length in the longitudinal direction from the longitudinal center portion to both ends of the heater. Therefore, it is possible to provide a fixing device that can increase the time until the substrate is broken and a heater used in the fixing device, as compared with the case where the resistance value distribution gradually decreases.

以下、本発明の実施例を図面に基づき説明する。   Embodiments of the present invention will be described below with reference to the drawings.

(1)画像形成装置例
図11に、本発明に係る加熱装置として画像加熱定着装置(以下、定着装置と記す)を備えた画像形成装置の一例を示す。同図に示す画像形成装置は、電子写真プロセス利用のレーザービームプリンタである。
(1) Example of Image Forming Apparatus FIG. 11 shows an example of an image forming apparatus provided with an image heat fixing device (hereinafter referred to as a fixing device) as a heating device according to the present invention. The image forming apparatus shown in the figure is a laser beam printer using an electrophotographic process.

画像形成装置は、像担持体としてドラム型の電子写真感光体(以下、感光ドラムと記す)1を備えている。感光ドラム1は、装置本体Mによって回転自在に支持されており、駆動手段(不図示)によって矢印R1方向に所定のプロセススピードで回転駆動される。   The image forming apparatus includes a drum-type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 1 as an image carrier. The photosensitive drum 1 is rotatably supported by the apparatus main body M, and is rotationally driven at a predetermined process speed in the direction of arrow R1 by a driving unit (not shown).

感光ドラム1の周囲には、その回転方向に沿って、帯電ローラ(帯電装置)2、露光手段3、現像装置4、転写ローラ(転写装置)5、クリーニング装置6がその順に配設されている。   Around the photosensitive drum 1, a charging roller (charging device) 2, an exposure unit 3, a developing device 4, a transfer roller (transfer device) 5, and a cleaning device 6 are arranged in that order along the rotation direction. .

また、装置本体Mの下部には、紙等のシート状の記録材Pを被加熱材として収納した給紙カセット7が配置されており、記録材Pの搬送経路に沿って上流側から順に、給紙ローラ15、搬送ローラ8、トップセンサー9、搬送ガイド10、本発明に係る加熱体を含む定着装置11、搬送ローラ12、排紙ローラ13、排紙トレイ14が配置されている。   In addition, a sheet feeding cassette 7 in which a sheet-like recording material P such as paper is stored as a material to be heated is disposed below the apparatus main body M, and sequentially from the upstream side along the conveyance path of the recording material P. A paper feed roller 15, a transport roller 8, a top sensor 9, a transport guide 10, a fixing device 11 including a heating body according to the present invention, a transport roller 12, a paper discharge roller 13, and a paper discharge tray 14 are arranged.

次に、上述構成の画像形成装置の動作を説明する。   Next, the operation of the image forming apparatus having the above configuration will be described.

駆動手段(不図示)によって矢印R1方向に回転駆動された感光ドラム1は、帯電ローラ2によって所定の極性、所定の電位に一様に帯電される。   The photosensitive drum 1 that is rotationally driven in the direction of arrow R1 by a driving means (not shown) is uniformly charged to a predetermined polarity and a predetermined potential by a charging roller 2.

帯電後の感光ドラム1は、その表面に対しレーザー光学系等の露光手段3によって画像情報に基づいた画像露光Lがなされ、露光部分の電荷が除去されて静電潜像が形成される。   The photosensitive drum 1 after charging is subjected to image exposure L based on the image information by the exposure means 3 such as a laser optical system on the surface, and the charge of the exposed portion is removed to form an electrostatic latent image.

静電潜像は、現像装置4によって現像される。現像装置4は、現像ローラ4aを有しており、この現像ローラ4aに現像バイアスを印加し、感光ドラム1上の静電潜像にトナーを付着させることで、トナー像としての現像(顕像化)をおこなう。   The electrostatic latent image is developed by the developing device 4. The developing device 4 includes a developing roller 4a. A developing bias is applied to the developing roller 4a, and toner is attached to the electrostatic latent image on the photosensitive drum 1, thereby developing the toner image (a visible image). ).

トナー像は、転写ローラ5によって紙等の記録材Pに転写される。記録材Pは、給紙カセット7に収納されており、給紙ローラ15・搬送ローラ8によって給紙・搬送され、トップセンサー9を介して、感光ドラム1と転写ローラ5との間の転写ニップ部に搬送される。このとき記録材Pは、トップセンサー9によって先端が検知され、感光ドラム1上のトナー像と同期がとられる。転写ローラ5には、転写バイアスが印加され、これにより感光ドラム1上のトナー像が記録材P上の所定の位置に転写される。   The toner image is transferred to the recording material P such as paper by the transfer roller 5. The recording material P is stored in a paper feed cassette 7, fed and transported by a paper feed roller 15 and a transport roller 8, and a transfer nip between the photosensitive drum 1 and the transfer roller 5 via a top sensor 9. It is conveyed to the part. At this time, the leading edge of the recording material P is detected by the top sensor 9 and synchronized with the toner image on the photosensitive drum 1. A transfer bias is applied to the transfer roller 5, whereby the toner image on the photosensitive drum 1 is transferred to a predetermined position on the recording material P.

転写によって表面に未定着トナー像を担持した記録材Pは、搬送ガイド10に沿って定着装置11に搬送され、ここで未定着トナー像が加熱・加圧されて記録材P表面に定着される。なお、定着装置11については後に詳述する。   The recording material P carrying the unfixed toner image on the surface by transfer is transported to the fixing device 11 along the transport guide 10, where the unfixed toner image is heated and pressurized and fixed on the surface of the recording material P. . The fixing device 11 will be described in detail later.

トナー像定着後の記録材Pは、搬送ローラ12・排出ローラ13によって装置本体M上面の排紙トレイ14上に搬送・排出される。   The recording material P after the toner image is fixed is transported and discharged onto a paper discharge tray 14 on the upper surface of the apparatus main body M by a transport roller 12 and a discharge roller 13.

一方、トナー像転写後の感光ドラム1は、記録材Pに転写されないで表面に残ったトナー(転写残トナー)がクリーニング装置6のクリーニングブレード6aによって除去され、次の画像形成に備える。 On the other hand, the photosensitive drum 1 after the toner image transfer, the toner remaining on the surface without being transferred to the recording material P (rolling Utsushizan toner over) is removed by a cleaning blade 6a of the cleaning device 6, ready for the next image formation.

以上の動作を繰り返すことで、次々と画像形成を行うことができる。   By repeating the above operation, image formation can be performed one after another.

(2)定着装置11
図1に、本発明に基づくフィルム加熱方式の定着装置の概略断面図を示す。
(2) Fixing device 11
FIG. 1 is a schematic cross-sectional view of a film heating type fixing device according to the present invention.

本実施例の定着装置11は加圧ローラ駆動式であり、加熱体(ヒータ)100を保持させた加熱体支持体20を、可撓性部材としての円筒状の耐熱性フィルム(筒状の定着フィルム)30を介して加圧部材である加圧ローラ40に所定の押圧力をもって圧接させ、加熱体100との間に定着ニップ部Nを形成している。 The fixing device 11 of this embodiment is a pressure roller drive type heater (Heater) 100 heating member support body 20 is held with a cylindrical heat-resistant film as the flexible member (tubular The fixing nip portion N is formed between the heating member 100 and the pressure roller 40, which is a pressure member, with a predetermined pressing force.

回転制御手段としての回転駆動部80によって加圧ローラ40が矢印bの方向に回転駆動され、加圧ローラ40の回転による耐熱性フィルム30外面との摺動摩擦力により、フィルム30に回転力が作用してフィルム30がフィルム30の内面と加熱体100が接触した状態に(図1参照)加熱体支持体20の外回りを矢印aの方向に回転し、電力供給手段としての加熱体駆動回路70によって加熱体100に対して通電加熱されることにより加熱体100が所定のプリント温調に制御される。この状態において、未定着トナー像Tを担持した記録材Pを定着ニップ部Nで矢印cの方向に挟持搬送することにより、加熱体100の熱が耐熱性フィルム30を介して記録材Pに付与され、未定着トナー像Tが記録材P面に熱定着される。定着ニップ部Nを通過した記録材Pは耐熱性フィルム30の面から曲率分離されて排紙される。なお、本実施例の定着装置において、記録材Pの通紙基準は各部材の長手方向(記録材Pの搬送方向cに直交する方向)における中央部としている。 The pressure roller 40 is rotationally driven in the direction of arrow b by the rotation drive unit 80 as a rotation control means, and the rotational force acts on the film 30 by the sliding frictional force with the outer surface of the heat resistant film 30 due to the rotation of the pressure roller 40. Then, the film 30 rotates in the direction of the arrow a in a state where the inner surface of the film 30 and the heating body 100 are in contact with each other (see FIG. 1), and is heated by a heating body driving circuit 70 as power supply means. When the heating body 100 is energized and heated, the heating body 100 is controlled to a predetermined print temperature control. In this state, the recording material P carrying the unfixed toner image T is nipped and conveyed in the direction of the arrow c at the fixing nip N, so that the heat of the heating body 100 is applied to the recording material P through the heat resistant film 30. Then, the unfixed toner image T is thermally fixed on the recording material P surface. The recording material P that has passed through the fixing nip N is separated from the surface of the heat resistant film 30 and is discharged. In the fixing device of this embodiment, the sheet passing reference of the recording material P is the central portion in the longitudinal direction of each member (direction perpendicular to the conveyance direction c of the recording material P).

加熱体100は、細長いアルミナ等の耐熱性の基板104上に、3本の発熱パターン101a(101a−1・101a−2)・101bと、該発熱体を被覆する表面保護層105を形成具備させたものである。加熱体100については次の(3)項でさらに詳しく説明する。   The heating element 100 includes three heat generation patterns 101a (101a-1, 101a-2), 101b and a surface protection layer 105 covering the heat generation element on a heat resistant substrate 104 such as elongated alumina. It is a thing. The heating element 100 will be described in more detail in the next item (3).

円筒状の耐熱性フィルム30は例えば厚み30μm〜100μm程度のポリイミドを基層とした薄膜筒で、基層の上にプライマー層を介してPFA、PTFE等のコートが施されており、トナーとの離型性を保っている。また、フィルム30内面と加熱体支持体20との間には不図示の摺動グリスが塗布されており、フィルム30の摺動性を保っている。   The cylindrical heat-resistant film 30 is, for example, a thin film cylinder having a polyimide base layer with a thickness of about 30 μm to 100 μm. The base layer is coated with PFA, PTFE, etc. via a primer layer, and is released from the toner. Keeps sex. Further, a sliding grease (not shown) is applied between the inner surface of the film 30 and the heating body support 20 to maintain the slidability of the film 30.

加圧ローラ30は芯金上に例えばシリコーンゴムなどの弾性層を基層とした回転体で、基層の上にプライマー層を介して10〜100μm程度の厚みを有するFEP、PFA等の離型層を設けて構成され、トナーとの離型性を保っている。   The pressure roller 30 is a rotating body having an elastic layer such as silicone rubber as a base layer on a core metal, and a release layer such as FEP or PFA having a thickness of about 10 to 100 μm is provided on the base layer through a primer layer. It is provided and maintains releasability from the toner.

加熱体支持体20は、断熱性・高耐熱性・剛性を有する、例えばポリフェニレンサルファイド(PPS)・ポリアミドイミド(PAI)・ポリイミド(PI)・ポリエーテルエーテルケトン(PEEK)・液晶ポリマー等の高耐熱性樹脂や、これ等の樹脂とセラミックス・金属・ガラス等との複合材料等で構成される。   The heating element support 20 has heat insulation, high heat resistance, and rigidity, such as high heat resistance such as polyphenylene sulfide (PPS), polyamide imide (PAI), polyimide (PI), polyether ether ketone (PEEK), and liquid crystal polymer. Or a composite material of these resins and ceramics, metal, glass or the like.

回転駆動部80は、加圧ローラ40を回転駆動するモータ81と、モータ81の回転を制御する制御部(CPU)82などを有する。モータ81としては、例えばDCモータやステッピングモータ等を使用することができる。   The rotational drive unit 80 includes a motor 81 that rotationally drives the pressure roller 40, a control unit (CPU) 82 that controls the rotation of the motor 81, and the like. As the motor 81, for example, a DC motor or a stepping motor can be used.

(3)加熱体100
図2に加熱体100の発熱パターン形成面と基板幅方向断面の概略構成図を示す。
(3) Heating body 100
FIG. 2 shows a schematic configuration diagram of a heating pattern forming surface of the heating body 100 and a cross section in the substrate width direction.

加熱体100は、例えば、長さ370mm・幅10mm・厚さ1mmのアルミナ、窒化アルミ等の耐熱性・電気絶縁性・低熱容量のセラミック基材(本実施例1ではアルミナ)を用いた細長い基板(セラミック基板)104の片面側(セラミック基板上)に、Ag/Pd等の3本の発熱パターン(発熱抵抗体)101a(101a−1・101a−2)及び101bと、前記発熱パターン101に給電し得る電極パターンとしての給電電極102(102a・102b)及び共通電極103を形成している。つまり基板014上には、基板104の幅方向(短手方向)の中央に1本、前記中央を基準にして対称な位置関係で2本、合計3本の発熱101a−1・101a−2,101bが設けられている。 The heating body 100 is, for example, an elongated substrate using a ceramic base material (alumina in this embodiment 1) having a heat resistance, electrical insulation, and low heat capacity, such as alumina having a length of 370 mm, a width of 10 mm, and a thickness of 1 mm. feeding the (ceramic substrate) 104 one side of (on a ceramic substrate), three heating pattern (heat generating resistor), such as Ag / Pd 101a and (101a-1 · 101a-2 ) and 101b, the heating pattern 101 The power supply electrodes 102 (102a and 102b) and the common electrode 103 are formed as possible electrode patterns. That is, on the substrate 014, one heat generation 101 a-1 and 101 a-2 in total, one at the center in the width direction (short direction) of the substrate 104 and two in a symmetrical positional relationship with respect to the center. 101b is provided.

次に、発熱パターン101a・101bの詳細構成について説明する。   Next, a detailed configuration of the heat generation patterns 101a and 101b will be described.

2本の発熱パターン101a−1・101a−2は、基板片面の長手方向一端部側に設けた給電電極102aから長手方向他端部側に設けた共通電極103にかけて通電され得る発熱抵抗体であり、図2(a)のように基板幅方向(基板短手方向)の一端側と他端側に配置され、基板104の長手方向に沿って形成されている。この発熱パターン101a−1・101a−2は、互いに直列に接続されて第1の導通経路を構成し、それぞれ基板短手方向略中央Cを基準にして略対称な領域に形成されている。つまり前記基準に対して対称の位置関係にある2本の発熱パターン101a−1・101a−2は常に同時に発熱するように一対の電極間(給電電極102aと共通電極103の間)に直列に接続されている。そして発熱パターン101a−1・101a−2はそれぞれ、長手中央付近から端部にかけて多段階的にパターン幅を広げることによって単位長さ当り抵抗値(抵抗値分布)を小さくし、通電させた場合に基板104の長さ方向における所定の基準位置すなわち略長手中央(発熱パターン形成領域の略中央位置)を発熱ピークとする山型発熱分布(発熱量分布)をなすように形成されている(以下、「山型発熱パターン」ともいう)。本実施例では、発熱パターン101a−1・101a−2において、図2(a)の長手中央付近の基板幅方向のα−α線分付近における単位長さ当り抵抗値を端部付近の基板幅方向のβ−β線分付近における単位長さ当り抵抗値の1.2倍となるように、発熱パターン101a−1・101a−2それぞれのパターン幅を調整している。 The two heat generation patterns 101a-1 and 101a-2 are heat generation resistors that can be energized from the feeding electrode 102a provided on one side of the substrate in the longitudinal direction to the common electrode 103 provided on the other side in the longitudinal direction. As shown in FIG. 2A, they are disposed on one end side and the other end side in the substrate width direction (substrate short direction), and are formed along the longitudinal direction of the substrate 104. The heat generation patterns 101a-1 and 101a-2 are connected to each other in series to form a first conduction path, and are formed in regions that are substantially symmetrical with respect to the approximate center C in the short-side direction of the substrate. In other words, the two heat generation patterns 101a-1 and 101a-2 having a symmetrical positional relationship with respect to the reference are connected in series between a pair of electrodes (between the feeding electrode 102a and the common electrode 103) so as to always generate heat simultaneously. Has been. Each of the heat generation patterns 101a-1 and 101a-2 has a resistance value (resistance value distribution) per unit length that is reduced by enlarging the pattern width in multiple steps from the vicinity of the longitudinal center to the end portion. It is formed so as to form a mountain-shaped heat generation distribution (heat generation amount distribution) having a heat generation peak at a predetermined reference position in the length direction of the substrate 104, that is, approximately the center in the longitudinal direction (substantially the center position of the heat generation pattern formation region ) Also called “mountain heat generation pattern”). In this embodiment, in the heat generation patterns 101a-1 and 101a-2, the resistance value per unit length in the vicinity of the α-α line segment in the substrate width direction in the vicinity of the longitudinal center in FIG. The pattern widths of the heat generation patterns 101a-1 and 101a-2 are adjusted so that the resistance value per unit length near the β-β line segment in the direction is 1.2 times.

発熱パターン101bは、基板片面の長手方向一端部側に設けた給電電極102bから上記の共通電極103にかけて通電され得る発熱抵抗体であり、基板幅方向において前記発熱体パターン101a−1と101a−2との間に挟まれる位置(第1の導通経路の形成領域より内側の位置)に配置されて該発熱体パターンを含む導通経路以外の第2の導通経路を構成し、基板104の長さ方向に沿って形成されている。この発熱パターン101bも基板短手方向略中央Cを基準にして略対称な領域に形成されている。そして発熱パターン101bは、長手中央付近から端部にかけて多段階的にパターン幅を狭めることによって単位長さ当り抵抗値(抵抗値分布)を大きくし、通電させた場合に上記の所定の基準位置である略長手中央を発熱ボトムとする谷型発熱分布(発熱量分布)をなすように形成されている(以下、「谷型発熱パターン」ともいう)。本実施例では、発熱パターン101bにおいて、図2(a)の上記β−β線分付近における単位長さ当り抵抗値をα−α線分付近における単位長さ当り抵抗値の1.2倍となるように、発熱パターン101bのパターン幅を調整している。従って、発熱パターン101a−1・101a−2と発熱パターン101bにおいて、発熱パターン101a−1・101a−2は基板104の長手方向における単位長さ当りの発熱量分布が当該発熱パターン以外の発熱パターン101bと異なっている。また、発熱パターン101bは基板104の長手方向における単位長さ当りの発熱量分布が当該発熱パターン以外の発熱パターン101a−1・101a−2と異なっている。 The heat generation pattern 101b is a heat generation resistor that can be energized from the power supply electrode 102b provided on one end side in the longitudinal direction on one side of the substrate to the common electrode 103, and the heat generation element patterns 101a-1 and 101a-2 in the substrate width direction. And a second conduction path other than the conduction path including the heating element pattern is disposed at a position sandwiched between (a position inside the region where the first conduction path is formed) and the length direction of the substrate 104 It is formed along. The heat generation pattern 101b is also formed in a substantially symmetric region with respect to the approximate center C in the lateral direction of the substrate. The heat generation pattern 101b increases the resistance value (resistance value distribution) per unit length by narrowing the pattern width in multiple steps from the vicinity of the longitudinal center to the end, and when energized, at the predetermined reference position described above. It is formed so as to form a valley-shaped heat generation distribution (heat generation amount distribution) having a heat generation bottom at a substantially longitudinal center (hereinafter also referred to as “valley-type heat generation pattern”). In this embodiment, in the heat generation pattern 101b, the resistance value per unit length near the β-β line segment in FIG. 2A is 1.2 times the resistance value per unit length near the α-α line segment. Thus, the pattern width of the heat generation pattern 101b is adjusted. Accordingly, in the heat generation patterns 101a-1 and 101a-2 and the heat generation pattern 101b, the heat generation patterns 101a-1 and 101a-2 have a heat generation amount distribution per unit length in the longitudinal direction of the substrate 104 of the heat generation pattern 101b other than the heat generation pattern. Is different. The heat generation pattern 101b is different from the heat generation patterns 101a-1 and 101a-2 other than the heat generation pattern in the heat generation amount distribution per unit length in the longitudinal direction of the substrate 104.

また発熱パターン101a・101bの抵抗値は各々Ra=20Ω(直列接続のためRa1=Ra2=10Ω)、Rb=20Ωに設定されており、それぞれの発熱パターンに対して120V印加させた場合に720Wずつの電力が発生されるように設定している。この抵抗設定の場合、図2(b)におけるα−α線分上の発熱パターン幅の関係について、例えばWa1=Wa2=1.6mm、Wb=0.8mm、パターン間隙0.5mmのような幅設定にすることにより、それぞれの発熱パターンを同一配合材料で形成させることが可能となる。   The resistance values of the heat generation patterns 101a and 101b are set to Ra = 20Ω (Ra1 = Ra2 = 10Ω for series connection) and Rb = 20Ω, respectively, and 720W when 120V is applied to each heat generation pattern. The power is set to be generated. In the case of this resistance setting, regarding the relationship of the heat generation pattern width on the α-α line segment in FIG. 2B, for example, a width such as Wa1 = Wa2 = 1.6 mm, Wb = 0.8 mm, and a pattern gap of 0.5 mm. By setting, it becomes possible to form each heat generation pattern with the same compounding material.

そして図2(b)に示すように、発熱パターン101a及び101bの形成領域Whは、加熱体基材104の基板幅Wcに対して略対称となるように形成され、定着ニップN内に収まるような領域幅に設定されている。本実施例ではWc=10mm、Wh=5mmに設定されている。   As shown in FIG. 2B, the formation regions Wh of the heat generating patterns 101a and 101b are formed so as to be substantially symmetric with respect to the substrate width Wc of the heating body base material 104 so as to be within the fixing nip N. Is set to an appropriate area width. In this embodiment, Wc = 10 mm and Wh = 5 mm are set.

図3の加熱体駆動回路70は、前記加熱体100の通電制御をつかさどる駆動回路の概略一例である。加熱体100に温度検知手段としてのサーミスタ50が当接あるいはその近傍に配置され、加熱体100の温度検知結果を制御部(制御手段)(CPU)71に出力している。CPU71はサーミスタ50の温度検知結果に基づいて所望の温度制御をするべく商用電源73に接続されたトライアック72a・72bの点灯タイミングを駆動制御する。ここでCPU71は、トライアック72a・72bの点灯比率を決定でき、所望の発熱比率をもって上記温度制御を施すことができる。そして商用電源73から発熱パターン101a−1・101a−2へのACラインには、CPU71からの信号に応じてACラインを導通状態と遮断状態に切り換えるトライアック(第1の駆動素子)72aが設けられている。また商用電源73から発熱パターン101bへのACラインには、CPU71からの信号に応じてACラインを導通状態と遮断状態に切り換えるトライアック(第2の駆動素子)72bが設けられている。加熱体駆動回路70による加熱体100への電力制御は、電源波形の半波ごとに通電の実行と停止を制御するゼロクロス波数制御や、電源波形の半波ごとに通電する位相角を制御する位相制御等の多段階電力制御方法を用いている。 The heating body drive circuit 70 of FIG. 3 is a schematic example of a drive circuit that controls energization control of the heating body 100. A thermistor 50 as a temperature detecting means is in contact with or near the heating body 100, and the temperature detection result of the heating body 100 is output to a control unit (control means) (CPU) 71. The CPU 71 drives and controls lighting timings of the triacs 72a and 72b connected to the commercial power source 73 to perform desired temperature control based on the temperature detection result of the thermistor 50. Here, the CPU 71 can determine the lighting ratio of the triacs 72a and 72b, and can perform the temperature control with a desired heat generation ratio. The AC line from the commercial power supply 73 to the heat generation patterns 101a-1 and 101a-2 is provided with a triac (first drive element) 72a that switches the AC line between a conductive state and a cut-off state according to a signal from the CPU 71. ing. The AC line from the commercial power supply 73 to the heat generation pattern 101b is provided with a triac (second drive element) 72b that switches the AC line between a conductive state and a cut-off state in accordance with a signal from the CPU 71. The electric power control to the heating body 100 by the heating body driving circuit 70 includes zero-cross wave number control for controlling the execution and stop of energization for each half wave of the power supply waveform, and a phase for controlling the phase angle for energization for each half wave of the power supply waveform. A multi-stage power control method such as control is used.

また、加熱体100の過昇温を防止する安全素子60(温度ヒューズ、サーモスイッチ等)が通電ライン(電力供給回路)上に直列接続され、加熱体100に当接あるいは近傍に配置されることにより、加熱体100の熱暴走時(異常昇温時)に前記安全素子を作動させて加熱体100への通電を遮断できるように構成されている。本実施例1で用いた定着装置においては、安全素子60としてワコー電子社製サーモスイッチ:CH−16[定格作動温度250℃]を用いており、980W(抵抗値20Ωに対して電圧140V印加)の電力で暴走した場合、10±1秒で上記サーモスイッチ60が作動することが事前検討においてわかっている。 Further, a safety element 60 (temperature fuse, thermo switch, etc.) for preventing overheating of the heating body 100 is connected in series on the energization line (power supply circuit) and is placed in contact with or near the heating body 100. Thus, the heating element 100 is configured to be able to shut off the energization to the heating element 100 by operating the safety element during the thermal runaway of the heating element 100 ( at the time of abnormal temperature rise) . In the fixing device used in Example 1, a thermo switch manufactured by Wako Electronics Co., Ltd .: CH-16 [rated operating temperature 250 ° C.] is used as the safety element 60, and 980 W (voltage 140 V applied to a resistance value of 20Ω). It has been found in the preliminary examination that the thermo switch 60 operates in 10 ± 1 second when runaway with a power of 10 μm.

図4に、本実施例の定着装置においてトライアック72a・72bのうち一方が故障して加熱体100が熱暴走した場合に、加熱体100の幅方向断面に加わる熱ストレス分布をそれぞれ示す。本実施例では線膨張係数ε=7.2×10−6/℃、ヤング率E=340GPa、曲げ強度300MPaのアルミナ基板104を用いている。各々の分布は、常温からの140V印加時にトライアックが故障して熱暴走した3秒後における熱ストレス分布であり、上方が圧縮ストレス側、下方引張りストレス側を示す。前述のように引張りストレスの大きさが破損に関わり、引張りストレスの絶対値が大きいほど破損マージンが小さく、破損にいたるまでの時間が短くなる。 FIG. 4 shows thermal stress distributions applied to the cross-section in the width direction of the heating body 100 when one of the triacs 72a and 72b breaks down and the heating body 100 runs out of heat in the fixing device of this embodiment. In this embodiment, an alumina substrate 104 having a linear expansion coefficient ε = 7.2 × 10 −6 / ° C., Young's modulus E = 340 GPa, and bending strength 300 MPa is used. Each distribution is a thermal stress distribution after 3 seconds when the triac fails and thermal runaway occurs when 140 V is applied from room temperature, and the upper side indicates the compression stress side and the lower tensile stress side. As described above, the magnitude of the tensile stress is related to breakage, and the larger the absolute value of the tensile stress, the smaller the breakage margin and the shorter the time to breakage.

まず、トライアック72aが故障して山型発熱パターン101aが熱暴走した場合、引張りストレスの絶対値が最大になる箇所は、図2におけるα−α断面の基板両端部であり、140V印加3秒後において106MPaに達した。これはβ−β断面における引っ張りストレス最大値の約1.2倍の大きさである。サーモスイッチ60がなければ上記α−α断面の基板エッジ部から加熱体破損が生じ、発明者が検証したところ、破損に至るまでの所要時間は16秒であった。前述のようにサーモスイッチ60は熱暴走開始から10±1秒で作動するため、実施例1の定着装置においてトライアック72aが故障し熱暴走しても加熱体100が破損することなくサーモスイッチ60が作動して加熱体100への通電が停止される。   First, when the triac 72a breaks down and the mountain-shaped heat generation pattern 101a goes out of control, the portion where the absolute value of the tensile stress becomes maximum is the both ends of the substrate in the α-α cross section in FIG. Reached 106 MPa. This is about 1.2 times the maximum tensile stress in the β-β cross section. Without the thermo switch 60, the heating element was damaged from the substrate edge portion of the α-α cross section, and as a result of verification by the inventor, the time required to reach the damage was 16 seconds. As described above, since the thermo switch 60 operates in 10 ± 1 seconds from the start of the thermal runaway, even if the triac 72a fails in the fixing device of the first embodiment and the thermal runaway occurs, the thermo switch 60 is not damaged. The heater 100 is actuated to stop energizing the heating element 100.

また、トライアック72bが故障して谷型発熱パターン101bが熱暴走した場合、引張りストレスの絶対値が最大になる箇所は、図2におけるβ−β断面の基板両端部であり、140V印加3秒後において172MPaに達した。これはα−α断面における引っ張りストレス最大値の約1.2倍の大きさである。サーモスイッチ60がなければ上記β−β断面の基板エッジ部から加熱体破損が生じ、発明者が検証したところ、破損に至るまでの所要時間は12秒であった。すなわち、実施例1の定着装置においてトライアック72bが故障し熱暴走しても加熱体100が破損することなくサーモスイッチ60が作動して加熱体100への通電が停止される。   When the triac 72b breaks down and the valley-shaped heat generation pattern 101b runs out of heat, the location where the absolute value of the tensile stress becomes maximum is the both ends of the substrate in the β-β cross section in FIG. At 172 MPa. This is about 1.2 times the maximum tensile stress in the α-α cross section. Without the thermo switch 60, the heating element was damaged from the substrate edge portion of the β-β cross section, and as a result of verification by the inventor, the time required until the damage was 12 seconds. That is, even if the triac 72b breaks down in the fixing device of the first embodiment and the thermal runaway occurs, the thermoswitch 60 operates without stopping the heating body 100 and the energization to the heating body 100 is stopped.

比較例として、従来の加熱体900の場合について説明する。図12(c)に示すように加熱体900は、基板904の片面側に、発熱パターン901a及び901b、給電電極902a・902b、及び共通電極903等を形成している。   As a comparative example, the case of a conventional heating body 900 will be described. As shown in FIG. 12C, the heating element 900 has heating patterns 901a and 901b, power supply electrodes 902a and 902b, a common electrode 903, and the like formed on one side of the substrate 904.

発熱パターン901aは、給電電極902aから共通電極903にかけて通電され得る
1本の発熱抵抗体であり、長手中央付近から端部にかけて多段階的にパターン幅を広げることによって単位長さ当り抵抗値を小さくした山型発熱パターンを形成している。図12(c)のα−α線分付近における単位長さ当り抵抗値はβ−β線分付近における単位長さ当り抵抗値の1.2倍となっている。
The heat generation pattern 901a is a single heat generation resistor that can be energized from the feeding electrode 902a to the common electrode 903, and the resistance value per unit length is reduced by increasing the pattern width in multiple steps from the vicinity of the center to the end. A chevron-shaped heat generation pattern is formed. The resistance value per unit length near the α-α line segment in FIG. 12C is 1.2 times the resistance value per unit length near the β-β line segment.

発熱パターン901bは、給電電極902bから共通電極903にかけて通電され得る1本の発熱抵抗体であり、長手中央付近から端部にかけて多段階的にパターン幅を狭めることによって単位長さ当り抵抗値を大きくした谷型発熱パターンを形成している。図12(c)のβ−β線分付近における単位長さ当り抵抗値はα−α線分付近における単位長さ当り抵抗値の1.2倍となっている。   The heat generation pattern 901b is a single heat generation resistor that can be energized from the feeding electrode 902b to the common electrode 903, and the resistance value per unit length is increased by narrowing the pattern width in multiple steps from the vicinity of the longitudinal center to the end. A valley-shaped heat generation pattern is formed. The resistance value per unit length near the β-β line segment in FIG. 12C is 1.2 times the resistance value per unit length near the α-α line segment.

発熱パターン901a・901bの抵抗値は各々Ra=20Ω、Rb=20Ωに設定されており、それぞれの発熱パターンに対して120V印加させた場合に720Wずつの電力が発生されるように設定している。この抵抗設定の場合、図12(d)におけるα−α線分上の発熱パターン幅の関係について、例えばWa=2mm、Wb=2.4mm、パターン間隙0.6mmのような幅設定にすることにより、それぞれの発熱パターンを同一配合材料で形成させることが可能となる。   The resistance values of the heat generation patterns 901a and 901b are set to Ra = 20Ω and Rb = 20Ω, respectively, and set to generate 720 W of power when 120V is applied to each heat generation pattern. . In the case of this resistance setting, regarding the relationship between the heat generation pattern widths on the α-α line segment in FIG. 12 (d), for example, width settings such as Wa = 2 mm, Wb = 2.4 mm, and pattern gap 0.6 mm are set. Thus, it becomes possible to form each heat generation pattern with the same blending material.

そして図12(d)に示すように、発熱パターン901a及び901bの形成領域Whは、加熱体基材904の基板幅Wcに対して略対称となるように形成され、定着ニップN内に収まるような領域幅に設定されており、本比較例ではWc=10mm、Wh=5mmに設定されている。   Then, as shown in FIG. 12D, the formation regions Wh of the heat generation patterns 901a and 901b are formed so as to be substantially symmetric with respect to the substrate width Wc of the heating element base 904 so as to be within the fixing nip N. In this comparative example, Wc = 10 mm and Wh = 5 mm are set.

上記加熱体900を図13(a)に示す加熱体駆動回路70に組み込んだ定着装置において、トライアック72a・72bのうち一方が故障して加熱体900が熱暴走した場合に、加熱体900の幅方向断面に加わる熱ストレス分布を図14に示す。   In the fixing device in which the heating body 900 is incorporated in the heating body drive circuit 70 shown in FIG. 13A, when one of the triacs 72a and 72b breaks down and the heating body 900 runs out of heat, the width of the heating body 900 is increased. FIG. 14 shows the thermal stress distribution applied to the directional cross section.

まず、トライアック72aが故障して山型発熱パターン901aが熱暴走した場合、引張りストレスの絶対値が最大になる箇所は、図12(c)におけるα−α断面の基板端部A1であり、140V印加3秒後において225MPaに達した。破損に至るまでの所要時間を検証したところ、8秒となり、サーモスイッチ60の作動以前に加熱体900が破損した。   First, when the triac 72a breaks down and the mountain-shaped heat generation pattern 901a goes out of control, the portion where the absolute value of the tensile stress becomes maximum is the substrate end A1 of the α-α cross section in FIG. It reached 225 MPa after 3 seconds of application. When the time required to reach the breakage was verified, it was 8 seconds, and the heating element 900 was broken before the thermoswitch 60 was activated.

同様に、トライアック72bが故障して谷型発熱パターン901bが熱暴走した場合、引張りストレスの絶対値が最大になる箇所は、図12(c)におけるβ−β断面の基板端部A2であり、140V印加3秒後において225MPaに達した。破損に至るまでの所要時間を検証したところ、8秒となり、サーモスイッチ60の作動以前に加熱体900が破損した。   Similarly, when the triac 72b fails and the valley-shaped heat generation pattern 901b runs out of heat, the place where the absolute value of the tensile stress becomes maximum is the substrate end A2 of the β-β cross section in FIG. It reached 225 MPa after 3 seconds of 140 V application. When the time required to reach the breakage was verified, it was 8 seconds, and the heating element 900 was broken before the thermoswitch 60 was activated.

上記のように本実施例によると、従来に対して発熱パターンの熱暴走時における熱ストレスを大幅に緩和でき、加熱体破損に対するマージンを確保でき、なおかつ非通紙部昇温の低減と定着性確保とを両立することが可能となった。これは主に、基板短手方向略中央Cを基準にした各発熱パターン配置構成の対称度合いによるものであり、従来の複数駆動発熱パターンにおいてはそれぞれの発熱パターンが非対称に配置されていたものを、本例のように同じ導通経路上の2つの発熱パターンを基板幅の一端側と他端側に配置し、他の導通経路上の発熱パターンを基板幅方向で挟み込むことによって、いずれの通電においても上記基板短手方向略中央Cに対する発熱対称度を確保できる構成にすることが可能となったためである。これによってヒータの耐久性・信頼性を向上でき、ひいては定着装置の品質・信頼性を向上させることができる。   As described above, according to the present embodiment, the thermal stress during the thermal runaway of the heat generation pattern can be greatly reduced compared to the conventional case, the margin for the heating element breakage can be secured, and the non-sheet passing portion temperature rise can be reduced and the fixing property can be secured. It has become possible to balance securing. This is mainly due to the degree of symmetry of each heat generation pattern arrangement configuration with reference to approximately the center C in the lateral direction of the substrate. In the conventional multiple drive heat generation pattern, each heat generation pattern is arranged asymmetrically. As in this example, two heating patterns on the same conduction path are arranged on one end side and the other end side of the substrate width, and the heating pattern on the other conduction path is sandwiched in the substrate width direction, so This is because it is possible to achieve a configuration that can secure the degree of heat generation symmetry with respect to the approximate center C in the short-side direction of the substrate. As a result, the durability and reliability of the heater can be improved, and as a result, the quality and reliability of the fixing device can be improved.

なお、本実施例1においては山型発熱分布をなす発熱パターンを基板幅方向の両端側、谷型発熱分布をなす発熱パターンをその内側に配置した場合について説明したが、図5(a)に示すように逆の発熱分布構成を有する加熱体110でも同様な効果を得ることができる。   In the first embodiment, the case where the heat generation pattern forming the mountain-shaped heat generation distribution is arranged at both ends in the substrate width direction and the heat generation pattern forming the valley-type heat generation distribution is arranged inside thereof is shown in FIG. As shown, the same effect can be obtained with the heating element 110 having the opposite heat generation distribution configuration.

また、本実施例1においては基板幅方向に対して全く対称な発熱パターン配置構成について説明したが、これに限らず、同じ導通経路上の発熱パターンを基板幅の一端側と他端側に配置し、他の導通経路上の発熱パターンを基板幅方向で挟み込んでさえいれば、基板幅方向で完全対称な構成でなくとも相応の作用効果を期待できる。すなわち、図5(b)に示すように基板幅の一端側と他端側とで発熱分布が若干異なっている加熱体120においても、従来構成より発熱対称度を保つことができるため、加熱体破損に対するマージンをあまり損なわない。   In the first embodiment, the heat generation pattern arrangement configuration that is completely symmetrical with respect to the substrate width direction has been described. However, the present invention is not limited to this, and heat generation patterns on the same conduction path are arranged on one end side and the other end side of the substrate width. However, as long as the heat generation pattern on another conduction path is sandwiched in the substrate width direction, a corresponding effect can be expected even if the configuration is not completely symmetric in the substrate width direction. That is, as shown in FIG. 5 (b), even in the heating element 120 in which the heat generation distribution is slightly different between the one end side and the other end side of the substrate width, the degree of heat generation symmetry can be maintained compared to the conventional configuration. Not much damage margin for damage.

実施例1による作用効果は、以下に示す実施例2の構成によっても達成される。   The effect by Example 1 is achieved also by the structure of Example 2 shown below.

本実施例2に用いる加熱体200の概略構成の一例を図6に示す。加熱体200は、加熱体基板204の幅方向両端側に発熱パターン201a−1・201a−2を形成し、その内側に発熱パターン201bを形成している。上記発熱パターン201a−1・201a−2と201bのうち、発熱パターン201a−1・201a−2は給電電極202aと共通電極203との間に、互いに並列に接続されて第1の導通経路が形成されている。発熱パターン201bは給電電極202bと共通電極203との間に第2の導通経路を形成している。   An example of a schematic configuration of the heating body 200 used in the second embodiment is shown in FIG. In the heating body 200, heat generation patterns 201a-1 and 201a-2 are formed on both ends in the width direction of the heating body substrate 204, and a heat generation pattern 201b is formed inside thereof. Of the heat generation patterns 201a-1, 201a-2, and 201b, the heat generation patterns 201a-1 and 201a-2 are connected in parallel to each other between the power supply electrode 202a and the common electrode 203 to form a first conduction path. Has been. The heat generation pattern 201 b forms a second conduction path between the power supply electrode 202 b and the common electrode 203.

発熱パターン201a−1・201a−2は、実施例1と同様に長手中央付近から端部にかけて多段階的にパターン幅を広げることによって単位長さ当り抵抗値(抵抗値分布)を小さくした山型発熱パターンを形成している。発熱パターン201a−1・201a−2において、図6(a)の長手中央付近の基板幅方向のα−α線分付近における単位長さ当り抵抗値は端部付近の基板幅方向のβ−β線分付近における単位長さ当り抵抗値の1.2倍となっている。 The heat generation patterns 201a-1 and 201a-2 have a mountain shape in which the resistance value (resistance value distribution) per unit length is reduced by increasing the pattern width in multiple steps from the vicinity of the longitudinal center to the end as in the first embodiment. A heat generation pattern is formed. In the heat generation patterns 201a-1 and 201a-2, the resistance value per unit length in the vicinity of the α-α line segment in the substrate width direction near the longitudinal center in FIG. 6A is β-β in the substrate width direction in the vicinity of the edge. The resistance value per unit length in the vicinity of the line segment is 1.2 times.

発熱パターン201bは、実施例1と同様に長手中央付近から端部にかけて多段階的にパターン幅を狭めることによって単位長さ当り抵抗値を大きくした谷型発熱パターンを形成している。発熱パターン201bにおいて、図6(a)の上記β−β線分付近における単位長さ当り抵抗値(抵抗値分布)はα−α線分付近における単位長さ当り抵抗値の1.2倍となっている。 As in the first embodiment, the heat generation pattern 201b forms a valley heat generation pattern in which the resistance value per unit length is increased by narrowing the pattern width in multiple steps from the vicinity of the longitudinal center to the end. In the heat generation pattern 201b, the resistance value per unit length (resistance value distribution) near the β-β line segment in FIG. 6A is 1.2 times the resistance value per unit length near the α-α line segment. It has become.

発熱パターン201a・201bの抵抗値は各々Ra=20Ω(並列接続のためRa1=Ra2=40Ω)、Rb=20Ωに設定されており、それぞれの発熱パターンに対して120V印加させた場合に720Wずつの電力が発生されるように設定している。この抵抗設定の場合、図6(b)における発熱パターン幅の関係について、例えばWa1=Wa2=1mm、Wb=2mm、パターン間隙0.5mmのような幅設定にすることにより、それぞれの発熱パターンを同一配合材料で形成させることが可能となる。   The resistance values of the heat generation patterns 201a and 201b are set to Ra = 20Ω (Ra1 = Ra2 = 40Ω for parallel connection) and Rb = 20Ω, respectively. When 120V is applied to each heat generation pattern, the resistance value is 720W. The power is set to be generated. In the case of this resistance setting, with respect to the relationship between the heat generation pattern widths in FIG. 6B, for example, by setting the width such as Wa1 = Wa = 2 = 1 mm, Wb = 2 mm, and the pattern gap 0.5 mm, the respective heat generation patterns are changed. It becomes possible to form with the same compounding material.

そして図6(b)に示すように、発熱パターン201a及び201bの形成領域Whは、加熱体基材204の基板幅Wcに対して略対称となるように形成され、定着ニップN内に収まるような領域幅に設定されており、本実施例ではWc=10mm、Wh=5mmに設定されている。   As shown in FIG. 6B, the formation regions Wh of the heat generation patterns 201a and 201b are formed so as to be substantially symmetric with respect to the substrate width Wc of the heating body base material 204, and fit within the fixing nip N. In this embodiment, Wc = 10 mm and Wh = 5 mm.

実施例2では、上記Wa1・Wa2とWbとの関係が実施例1と異なる。加熱体基板204の両端側に形成された発熱パターン201a−1・201a−2は並列接続されて1つの導通経路をなしているため、実施例1と同じ電力を発生させるための発熱パターン201a−1・201a−2それぞれの抵抗設定は実施例1より高く設定されている(実施例1ではRa1=Ra2=10Ω、本実施例2ではRa1=Ra2=40Ω)。それに伴って、図6(b)におけるWa1とWa2をWbの約1/2倍に設定することが可能となる(実施例1におけるWa1とWa2はWbの約2倍)。   In the second embodiment, the relationship between the Wa1, Wa2, and Wb is different from the first embodiment. Since the heat generation patterns 201a-1 and 201a-2 formed on both ends of the heating body substrate 204 are connected in parallel to form one conduction path, the heat generation pattern 201a- for generating the same electric power as in the first embodiment is used. The resistance settings of 1.201a-2 are set higher than those in the first embodiment (Ra1 = Ra2 = 10Ω in the first embodiment, Ra1 = Ra2 = 40Ω in the second embodiment). Accordingly, Wa1 and Wa2 in FIG. 6B can be set to about ½ times Wb (Wa1 and Wa2 in Example 1 are about twice Wb).

上記加熱体200を図7に示す加熱体駆動回路70に組み込んだ定着装置において、トライアック72a・72bのうち一方が故障して加熱体200が熱暴走した場合に、加熱体200の幅方向断面に加わる熱ストレス分布を図8に示す。   In the fixing device in which the heating body 200 is incorporated in the heating body drive circuit 70 shown in FIG. 7, when one of the triacs 72 a and 72 b fails and the heating body 200 runs out of heat, a cross section in the width direction of the heating body 200 is obtained. The applied heat stress distribution is shown in FIG.

基板204の幅方向両端側に形成した発熱パターン201a−1・201a−2のパターン幅Wa1・Wa2が実施例1の場合より細いとき、トライアック72aの故障による加熱体200の熱暴走時において、基板幅中心部の温度上昇が抑えられ、基板幅両端部の温度上昇が促進される傾向となるため、図8(a)に示すような熱ストレス分布となり、加熱体200の基板幅方向両端に加わる引張りストレスの最大値は、実施例1の場合より小さくなる。   When the pattern widths Wa1 and Wa2 of the heat generation patterns 201a-1 and 201a-2 formed on both ends in the width direction of the substrate 204 are narrower than in the case of the first embodiment, the substrate is subjected to thermal runaway due to a failure of the triac 72a. Since the temperature rise at the width center portion is suppressed and the temperature rise at both ends of the substrate tends to be promoted, a thermal stress distribution as shown in FIG. 8A is obtained and applied to both ends of the heating body 200 in the substrate width direction. The maximum value of tensile stress is smaller than that in the first embodiment.

また、発熱パターン201a−1・201a−2の内側に形成した発熱パターン201bのパターン幅Wbが実施例1の場合より太いとき、トライアック72bの故障による加熱体200の熱暴走時において、基板幅中心部の温度上昇が抑えられ、基板幅両端部の温度上昇が促進される傾向となるため、図8(b)に示すような熱ストレス分布となり、加熱体200の基板幅方向両端に加わる引張りストレスの最大値は、実施例1の場合より小さくなる。   When the pattern width Wb of the heat generation pattern 201b formed inside the heat generation patterns 201a-1 and 201a-2 is thicker than in the case of the first embodiment, the center of the substrate width at the time of thermal runaway of the heating body 200 due to the failure of the triac 72b Temperature rise at the both ends of the substrate tends to be suppressed, resulting in a thermal stress distribution as shown in FIG. 8B, and tensile stress applied to both ends of the heating body 200 in the substrate width direction. Is smaller than that in the first embodiment.

実施例1、実施例2、及び比較例における、山型発熱パターンと谷型発熱パターンそれぞれを980Wで熱暴走させたときの3秒後の引張りストレス最大値、熱暴走時加熱体破損の有無(安全素子60がない場合の破損時間)、安全素子60の作動有無についての検証結果を表1にまとめる。   In Example 1, Example 2, and Comparative Example, the maximum value of tensile stress after 3 seconds when each of the mountain-shaped heat generation pattern and the valley-shaped heat generation pattern was subjected to thermal runaway at 980 W, whether or not the heated body was damaged during thermal runaway ( Table 1 summarizes the verification results regarding whether or not the safety element 60 is activated).

以上、本実施例2のように加熱体基板幅方向両端側の発熱パターンを並列接続させて1つの導通経路を形成することにより、いずれかの発熱パターンの熱暴走時における引張りストレスを更に軽減することが可能となり、加熱体破損に対するマージンを上げることができた。   As described above, by forming a single conduction path by connecting the heating patterns at both ends in the width direction of the heating element substrate in parallel as in the second embodiment, the tensile stress during thermal runaway of any heating pattern is further reduced. It was possible to increase the margin for damage to the heating element.

実施例1による作用効果は、以下に示す実施例3の構成によっても達成される。   The effect by Example 1 is achieved also by the structure of Example 3 shown below.

実施例1、2においては、記録材の通紙基準が長手中央に設けられた定着装置およびそれに具備される加熱体について説明したが、本実施例3は記録材Pの通紙基準が各部材の長手方向(記録材Pの搬送方向cに直交する方向)における端部(長手端部)に設けられた定着装置およびそれに具備される加熱体の実施形態である。   In the first and second embodiments, the description has been given of the fixing device in which the sheet passing reference of the recording material is provided in the longitudinal center and the heating body provided in the fixing device. 3 is an embodiment of a fixing device provided at an end portion (longitudinal end portion) in a longitudinal direction (a direction orthogonal to the conveyance direction c of the recording material P) and a heating body provided therein.

図9は、通紙基準が長手端部に設けられた定着装置に具備される加熱体構成の一例である。加熱体構成以外の構成については実施例1、2と同様とした。加熱体300は、加熱体基板304の幅方向両端側に発熱パターン301a−1・301a−2を形成し、その内側に発熱パターン301bを形成している。上記発熱パターン301a−1・301a−2と301bのうち、発熱パターン301a−1・301a−2は給電電極302aと共通電極303との間に、互いに直列ないし並列に接続されて第1の導通経路が形成されている(本実施例では並列接続)。発熱パターン301bは給電電極302bと共通電極303との間に形成されて第2の導通経路を形成している。   FIG. 9 is an example of a heating element configuration provided in the fixing device in which the sheet passing reference is provided at the longitudinal end portion. The configuration other than the heating body configuration was the same as in Examples 1 and 2. In the heating body 300, heating patterns 301a-1 and 301a-2 are formed on both ends in the width direction of the heating body substrate 304, and a heating pattern 301b is formed on the inside thereof. Of the heat generation patterns 301a-1, 301a-2, and 301b, the heat generation patterns 301a-1 and 301a-2 are connected in series or in parallel to each other between the power supply electrode 302a and the common electrode 303 to form a first conduction path. Are formed (parallel connection in this embodiment). The heat generation pattern 301b is formed between the power supply electrode 302b and the common electrode 303 to form a second conduction path.

そして本実施例3において、発熱パターン301a(301a−1・301a−2)は加熱体300の長手方向の一端側(通紙基準S側)から他端側にかけて多段階的にパターン幅を広げることによって単位長さ当り抵抗値を小さくし、通電させた場合に基板104の長さ方向における所定の基準位置すなわち通紙基準S側(発熱パターン形成領域の端部近傍)から他端にかけて発熱量が小さくなるように形成されている。発熱パターン301bは逆に多段階的にパターン幅を狭めることによって単位長さ当り抵抗値を大きくし、通電させた場合に所定の基準位置である通紙基準S側から他端にかけて発熱量が大きくなるように形成されている。 In the third embodiment, the heat generation pattern 301a (301a-1 and 301a-2) has a pattern width that is increased in multiple steps from one end side (sheet passing reference S side) in the longitudinal direction of the heating body 300 to the other end side. The resistance value per unit length is reduced by the above, and when energized, the amount of heat generated from a predetermined reference position in the length direction of the substrate 104, that is, the sheet passing reference S side (near the end of the heat generation pattern forming region) to the other end. It is formed to be smaller. On the contrary, the heat generation pattern 301b increases the resistance value per unit length by narrowing the pattern width in multiple steps, and when energized, the heat generation amount increases from the paper passing reference S side, which is a predetermined reference position, to the other end. It is formed to become.

本実施例3の構成によれば、記録材の通紙基準が長手端部に設けられた定着装置において、加熱体に加わる熱ストレスを従来に対して低減させて定着装置暴走時の加熱体破損マージンを確保し、なおかつ非通紙部昇温の低減と定着性確保とを両立することが可能となった。   According to the configuration of the third embodiment, in the fixing device in which the sheet passing reference of the recording material is provided at the longitudinal end, the heat stress applied to the heating member is reduced as compared with the conventional case, and the heating member breaks when the fixing device runs away. It has become possible to secure a margin and achieve both reduction of the temperature rise at the non-sheet passing portion and securing of fixing property.

以上、本発明の実施例を説明したが、本発明はこれらの実施例にとらわれるものではなく技術思想内でのあらゆる変形が可能である。   Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be modified in various ways within the technical concept.

図10の(a)は本発明におけるヒータの他の例の説明図である。本発明の実施例においては、各発熱パターン幅の調整によって長手発熱分布を異ならせた加熱体の例を説明したが、図10(a)に示す加熱体310のように、基板314に設けられた3本の発熱パターン311a−1・311a−2・311bのパターン厚みや材料配合を長手で変化させることによって長手発熱分布を異ならせてもよい。また、長手発熱分布は滑らかに変化しなくてもよく、階段状の発熱分布を形成しうる加熱体であってもよい。なお、312a・312bは給電電極であり、313は共通電極である。 (A) of FIG. 10 is explanatory drawing of the other example of the heater in this invention. In the embodiment of the present invention, the example of the heating body in which the longitudinal heat generation distribution is made different by adjusting each heating pattern width has been described. However, like the heating body 310 shown in FIG. Further, the longitudinal heat generation distribution may be varied by changing the pattern thickness and material composition of the three heat generation patterns 311a-1, 311a-2, 311b in the longitudinal direction. The longitudinal heat generation distribution may not change smoothly, and may be a heating body that can form a step-like heat generation distribution. Note that 312a and 312b are power supply electrodes, and 313 is a common electrode.

同様に、図10(b)に示す加熱体320のように、基板324に設けられ長手発熱領域を異ならせた3本の発熱パターン321a−1・321a−2・321bにおいて、それぞれの配置・接続構成を本発明の技術思想内で構成してもよい。なお、322a・322bは給電電極であり、323は共通電極である。なお、図10(b)に示す加熱体320は本発明に係るヒータの参考例である。 Similarly, in the three heat generation patterns 321a-1, 321a-2, and 321b provided on the substrate 324 and having different longitudinal heat generation regions as in the heating body 320 shown in FIG. You may comprise a structure within the technical thought of this invention. Reference numerals 322a and 322b are power supply electrodes, and reference numeral 323 is a common electrode. In addition, the heating body 320 shown in FIG.10 (b) is a reference example of the heater which concerns on this invention.

さらに、図10(c)に示すように、3ドライブ以上の独立通電経路を有する加熱体330においても本発明の技術思想内で構成することが可能である。即ち、長手発熱分布の異なる3本以上の発熱パターン331a−1・331a−2・331b−1・331b−2・331cを基板324に設けるようにしてもよい。なお、332a・332bは給電電極であり、333は共通電極である。なお、図10(c)に示す加熱体330は本発明に係るヒータの参考例である。 Furthermore, as shown in FIG. 10 (c), a heating body 330 having an independent energization path of three or more drives can be configured within the technical idea of the present invention. That is, three or more heat generation patterns 331a-1, 331a-2, 331b-1, 331b-2, and 331c having different longitudinal heat generation distributions may be provided on the substrate 324. Note that 332a and 332b are power supply electrodes, and 333 is a common electrode. In addition, the heating body 330 shown in FIG.10 (c) is a reference example of the heater which concerns on this invention.

その他、加熱体基材はアルミナに限らず、窒化アルミニウム等、種々のセラミック基材において有用であり、発熱パターン形成面は加熱体基板の表裏いずれでも構わない。   In addition, the heating body base material is not limited to alumina but is useful for various ceramic base materials such as aluminum nitride, and the heating pattern forming surface may be on either the front or back side of the heating body substrate.

本発明における定着装置の概略断面図Schematic sectional view of a fixing device according to the present invention 実施例1における加熱体100の概略構成図Schematic configuration diagram of the heating element 100 in the first embodiment. 実施例1における加熱体100を用いた加熱体駆動回路の概略一例Schematic example of a heating element driving circuit using the heating element 100 in Example 1 実施例1における熱暴走時の熱ストレス分布Thermal stress distribution during thermal runaway in Example 1 実施例1におけるその他の加熱体構成例Example of other heating element configuration in Example 1 実施例2における加熱体200の概略構成図Schematic configuration diagram of the heating element 200 in the second embodiment. 実施例2における加熱体200を用いた加熱体駆動回路の概略一例Schematic example of a heating element driving circuit using the heating element 200 in the second embodiment 実施例2における熱暴走時の熱ストレス分布Thermal stress distribution during thermal runaway in Example 2 実施例3における加熱体300の概略構成図Schematic block diagram of heating element 300 in Example 3 (a)は本発明におけるヒータの他の例の説明図、(b)及び(c)はそれぞれ参考例のヒータの説明図(A) is explanatory drawing of the other example of the heater in this invention, (b) and (c) are explanatory drawings of the heater of a reference example, respectively. 本発明における定着装置を備える画像形成装置の概略構成図1 is a schematic configuration diagram of an image forming apparatus including a fixing device according to the present invention. 従来の加熱体構成例Conventional heating element configuration example 従来の加熱体を用いた加熱体駆動回路の概略一例Schematic example of a heating element drive circuit using a conventional heating element 従来の加熱体における熱暴走時の熱ストレス分布Thermal stress distribution during thermal runaway in conventional heating elements

符号の説明Explanation of symbols

100・110・120・200・300‥‥加熱体
20 ‥‥加熱体支持体
30 ‥‥耐熱性フィルム
40 ‥‥加圧ローラ
50 ‥‥サーミスタ
60 ‥‥安全素子
70 ‥‥加熱体駆動回路
72a・72b‥‥トライアック
N ‥‥定着ニップ
P ‥‥記録材
C ‥‥基板短手方向略中央
100, 110, 120, 200, 300 ... heating element 20 ... heating element support 30 ... heat resistant film 40 ... pressure roller 50 ... thermistor 60 ... safety element 70 ... heating element drive circuit 72a 72b ··· Triac N ··· Fixing nip P · · · Recording material C · · · Substrate in the short direction of the substrate

Claims (2)

筒状の定着フィルムと、セラミック基板と前記セラミック基板上に設けられた発熱抵抗体とを有し前記定着フィルムの内面に接触するヒータと、前記定着フィルムを介して前記ヒータと共にトナー像を担持する記録材を挟持搬送する定着ニップ部を形成する加圧部材と、商用電源から前記発熱抵抗体へ供給する電力を制御する制御手段と、商用電源から前記発熱抵抗体への電力供給回路に設けられており前記ヒータの異常昇温により作動して前記電力供給回路を遮断する安全素子と、を有し、前記セラミック基板上には前記セラミック基板の短手方向の中央に1本、前記中央を基準にして対称な位置関係で2本、合計3本の発熱抵抗体が設けられており、前記基準に対して対称の位置関係にある2本の発熱抵抗体は常に同時に発熱するように一対の電極間に直列または並列に接続されており、商用電源から前記対称な位置関係の2本の発熱抵抗体への電力供給回路には前記制御手段からの信号に応じて電力供給回路を導通状態と遮断状態に切り換える第1の駆動素子が設けられており、商用電源から前記中央の1本の発熱抵抗体への電力供給回路には前記制御手段からの信号に応じて電力供給回路を導通状態と遮断状態に切り換える第2の駆動素子が設けられている定着装置において、A heater having a cylindrical fixing film, a ceramic substrate and a heating resistor provided on the ceramic substrate, and contacting the inner surface of the fixing film, and carrying a toner image together with the heater via the fixing film A pressure member that forms a fixing nip for nipping and conveying the recording material; a control unit that controls power supplied from a commercial power source to the heating resistor; and a power supply circuit from a commercial power source to the heating resistor. And a safety element that operates due to an abnormal temperature rise of the heater and shuts off the power supply circuit. One on the ceramic substrate in the short direction center of the ceramic substrate and the center as a reference In total, three heating resistors are provided in a symmetrical positional relationship, and the two heating resistors in a symmetrical positional relationship with respect to the reference always generate heat at the same time. The power supply circuit is connected in series or in parallel between the pair of electrodes, and the power supply circuit from the commercial power supply to the two heating resistors having the symmetrical positional relationship is electrically connected according to the signal from the control means. A first drive element that switches between a state and a cut-off state is provided, and the power supply circuit from the commercial power supply to the one heating resistor at the center is connected to the power supply circuit according to a signal from the control means In the fixing device provided with the second drive element for switching between the state and the cutoff state,
前記対称な位置関係の2本の発熱抵抗体は、前記ヒータの長手方向中央部から両端部に向かって前記長手方向の単位長さあたりの抵抗値が徐々に小さくなる抵抗値分布となっており、前記中央の1本の発熱抵抗体は、前記ヒータの長手方向中央部から両端部に向かって前記長手方向の単位長さあたりの抵抗値が徐々に大きくなる抵抗値分布となっていることを特徴とする定着装置。The two heating resistors having the symmetrical positional relationship have a resistance value distribution in which the resistance value per unit length in the longitudinal direction gradually decreases from the longitudinal center portion of the heater toward both ends. The one heating resistor at the center has a resistance value distribution in which the resistance value per unit length in the longitudinal direction gradually increases from the longitudinal center portion of the heater toward both ends. A fixing device characterized.
筒状の定着フィルムと、セラミック基板と前記セラミック基板上に設けられた発熱抵抗体とを有し前記定着フィルムの内面に接触するヒータと、前記定着フィルムを介して前記ヒータと共にトナー像を担持する記録材を挟持搬送する定着ニップ部を形成する加圧部材と、商用電源から前記発熱抵抗体へ供給する電力を制御する制御手段と、商用電源から前記発熱抵抗体への電力供給回路に設けられており前記ヒータの異常昇温により作動して前記電力供給回路を遮断する安全素子と、を有し、前記セラミック基板上には前記セラミック基板の短手方向の中央に1本、前記中央を基準にして対称な位置関係で2本、合計3本の発熱抵抗体が設けられており、前記基準に対して対称の位置関係にある2本の発熱抵抗体は常に同時に発熱するように一対の電極間に直列または並列に接続されており、商用電源から前記対称な位置関係の2本の発熱抵抗体への電力供給回路には前記制御手段からの信号に応じて電力供給回路を導通状態と遮断状態に切り換える第1の駆動素子が設けられており、商用電源から前記中央の1本の発熱抵抗体への電力供給回路には前記制御手段からの信号に応じて電力供給回路を導通状態と遮断状態に切り換える第2の駆動素子が設けられている定着装置、に用いられるヒータにおいて、A heater having a cylindrical fixing film, a ceramic substrate and a heating resistor provided on the ceramic substrate, and contacting the inner surface of the fixing film, and carrying a toner image together with the heater via the fixing film A pressure member that forms a fixing nip for nipping and conveying the recording material; a control unit that controls power supplied from a commercial power source to the heating resistor; and a power supply circuit from a commercial power source to the heating resistor. And a safety element that operates due to an abnormal temperature rise of the heater and shuts off the power supply circuit. One on the ceramic substrate in the short direction center of the ceramic substrate and the center as a reference In total, three heating resistors are provided in a symmetrical positional relationship, and the two heating resistors in a symmetrical positional relationship with respect to the reference always generate heat at the same time. The power supply circuit is connected in series or in parallel between the pair of electrodes, and the power supply circuit from the commercial power supply to the two heating resistors having the symmetrical positional relationship is electrically connected according to the signal from the control means. A first drive element that switches between a state and a cut-off state is provided, and the power supply circuit from the commercial power supply to the one heating resistor at the center is connected to the power supply circuit according to a signal from the control means In a heater used in a fixing device provided with a second drive element that switches between a state and a cutoff state,
前記対称な位置関係の2本の発熱抵抗体は、前記ヒータの長手方向中央部から両端部に向かって前記長手方向の単位長さあたりの抵抗値が徐々に小さくなる抵抗値分布となっており、前記中央の1本の発熱抵抗体は、前記ヒータの長手方向中央部から両端部に向かって前記長手方向の単位長さあたりの抵抗値が徐々に大きくなる抵抗値分布となっていることを特徴とするヒータ。The two heating resistors having the symmetrical positional relationship have a resistance value distribution in which the resistance value per unit length in the longitudinal direction gradually decreases from the longitudinal center portion of the heater toward both ends. The one heating resistor at the center has a resistance value distribution in which the resistance value per unit length in the longitudinal direction gradually increases from the longitudinal center portion of the heater toward both ends. Characteristic heater.
JP2004182418A 2004-06-21 2004-06-21 Fixing device and heater used in the fixing device Active JP4208772B2 (en)

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CNB2005100772775A CN100555111C (en) 2004-06-21 2005-06-21 Image heater and be used for the well heater of this device
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