JP6129248B2 - Heater and image heating apparatus equipped with the heater - Google Patents
Heater and image heating apparatus equipped with the heater Download PDFInfo
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- JP6129248B2 JP6129248B2 JP2015138173A JP2015138173A JP6129248B2 JP 6129248 B2 JP6129248 B2 JP 6129248B2 JP 2015138173 A JP2015138173 A JP 2015138173A JP 2015138173 A JP2015138173 A JP 2015138173A JP 6129248 B2 JP6129248 B2 JP 6129248B2
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Description
本発明は、電子写真複写機、電子写真プリンタなどの画像形成装置に搭載される加熱定着装置に利用すれば好適なヒータ、及びこのヒータを搭載する像加熱装置に関する。 The present invention relates to a heater suitable for use in a heating and fixing device mounted in an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer, and an image heating apparatus including the heater.
複写機やプリンタに搭載する定着装置として、エンドレスベルトと、エンドレスベルトの内面に接触するセラミックヒータと、エンドレスベルトを介してセラミックヒータと定着ニップ部を形成する加圧ローラと、を有する装置がある。この定着装置を搭載する画像形成装置で小サイズ紙を連続プリントすると、定着ニップ部長手方向において紙が通過しない領域の温度が徐々に上昇するという現象（非通紙部昇温）が発生する。非通紙部の温度が高くなり過ぎると、装置内の各パーツへダメージを与えたり、非通紙部昇温が生じている状態で大サイズ紙にプリントすると、小サイズ紙の非通紙部に相当する領域でトナーが高温オフセットすることもある。 As a fixing device mounted on a copying machine or a printer, there is an apparatus having an endless belt, a ceramic heater that contacts an inner surface of the endless belt, and a pressure roller that forms a fixing nip portion with the ceramic heater via the endless belt. . When small-size paper is continuously printed by an image forming apparatus equipped with this fixing device, a phenomenon (temperature increase of the non-sheet passing portion) occurs in which the temperature of the region where the paper does not pass in the longitudinal direction of the fixing nip portion gradually increases. If the temperature of the non-sheet passing part becomes too high, the parts in the device will be damaged, or if printing on large size paper with the non-sheet passing part temperature rise, the non-sheet passing part of small size paper The toner may be offset at a high temperature in a region corresponding to.
この非通紙部昇温を抑制する手法の一つとして、セラミック基板上の発熱抵抗体を負の抵抗温度特性を有する材質で形成することが考えられている。非通紙部が昇温しても非通紙部の発熱抵抗体の抵抗値は下がるので、非通紙部の発熱抵抗体に電流が流れても非通紙部の発熱が抑えられるという発想である。負の抵抗温度特性は、温度が上がると抵抗が下がる特性であり、以後ＮＴＣ（Ｎｅｇａｔｉｖｅ Ｔｅｍｐｅｒａｔｕｒｅ Ｃｏｅｆｆｉｃｉｅｎｔ）と称する。逆に、発熱抵抗体を正の抵抗温度特性を有する材質で形成することも考えられている。非通紙部が昇温すると非通紙部の発熱抵抗体の抵抗値が昇温し、非通紙部の発熱抵抗体に流れる電流が抑制されることにより非通紙部の発熱を抑制するという発想である。正の抵抗温度特性は、温度が上がると抵抗が上がる特性であり、以後ＰＴＣ（Ｐｏｓｉｔｉｖｅ Ｔｅｍｐｅｒａｔｕｒｅ Ｃｏｅｆｆｉｃｉｅｎｔ）と称する。 As one method for suppressing the temperature rise of the non-sheet passing portion, it is considered that the heating resistor on the ceramic substrate is formed of a material having a negative resistance temperature characteristic. Since the resistance value of the heating resistor in the non-sheet-passing portion decreases even when the temperature of the non-sheet-passing portion rises, the idea that heat generation in the non-sheet-passing portion can be suppressed even if current flows through the heating resistor in the non-sheet passing portion It is. The negative resistance temperature characteristic is a characteristic in which the resistance decreases as the temperature increases, and is hereinafter referred to as NTC (Negative Temperature Coefficient). Conversely, it is also considered that the heating resistor is formed of a material having a positive resistance temperature characteristic. When the temperature of the non-sheet-passing part rises, the resistance value of the heating resistor in the non-sheet-passing part rises, and the current flowing through the heating resistor in the non-sheet-passing part is suppressed, thereby suppressing the heat generation in the non-sheet passing part. This is the idea. The positive resistance temperature characteristic is a characteristic in which the resistance increases as the temperature rises, and is hereinafter referred to as PTC (Positive Temperature Coefficient).
しかしながら、一般的にＮＴＣの材質は体積抵抗が非常に高く、一本のヒータに形成する発熱抵抗体の総抵抗を、商用電源で使用できる範囲内に設定するのは非常に難しい。逆にＰＴＣの材質は体積抵抗が非常に低く、ＮＴＣの場合と同様、一本のヒータの発熱抵抗体の総抵抗を、商用電源で使用できる範囲内に設定するのは非常に難しい。 However, in general, the material of NTC has a very high volume resistance, and it is very difficult to set the total resistance of the heating resistor formed in one heater within a range that can be used with a commercial power source. On the contrary, the material of PTC has a very low volume resistance, and it is very difficult to set the total resistance of the heating resistor of one heater within a range that can be used with a commercial power source, as in the case of NTC.
そこで、セラミック基板上に形成する発熱抵抗体をヒータの長手方向で複数のブロックに分割し、各ブロックではヒータの短手方向（記録紙の搬送方向）に電流が流れるように二本の電極を基板の短手方向の両端に配置する。更に複数のブロックを電気的に直列に繋ぐ構成が特許文献１に開示されている。このような形状にすれば、発熱抵抗体の材質がＮＴＣの場合、各ブロックの抵抗値が低くなり、ヒータの長手方向に電流を流す場合と比較してヒータ全体の総抵抗を低く抑えることができる。また、発熱抵抗体の材質がＰＴＣの場合、複数のブロックに分割せずにヒータの短手方向に電流を流す場合と比較してヒータ全体の総抵抗を高くすることができる。 Therefore, the heating resistor formed on the ceramic substrate is divided into a plurality of blocks in the longitudinal direction of the heater, and each block has two electrodes so that current flows in the short direction of the heater (recording paper transport direction). It arrange | positions at the both ends of the transversal direction of a board | substrate. Further, Patent Document 1 discloses a configuration in which a plurality of blocks are electrically connected in series. With such a shape, when the material of the heating resistor is NTC, the resistance value of each block is low, and the total resistance of the entire heater can be kept low compared with the case where current flows in the longitudinal direction of the heater. it can. Further, when the material of the heating resistor is PTC, the total resistance of the entire heater can be increased as compared with the case where a current is passed in the short direction of the heater without being divided into a plurality of blocks.
ただし、発熱抵抗体を複数の発熱ブロックに分割すると、隣り合う発熱ブロック間に隙間ができてしまい、発熱分布ムラができてしまう。そこで、特許文献１では、発熱ブロックの形状を平行四辺形にすることで、ヒータ長手方向で発熱しない領域が生じないようにしている。 However, when the heat generating resistor is divided into a plurality of heat generating blocks, a gap is formed between adjacent heat generating blocks, resulting in uneven heat generation distribution. Therefore, in Patent Document 1, the shape of the heat generation block is a parallelogram so that no region that does not generate heat in the longitudinal direction of the heater does not occur.
しかしながら、特許文献１に開示されている発熱ブロックの形状では、発熱分布ムラを抑制する効果として不十分であることがその後の検討で判明した。図１２はこのヒータの一部を示している。２２ａは細長い基板であり、この基板上に導電パターン２９ｑ（２２ｑ１、２２ｑ２・・・）と導電パターン２９ｒ（２２ｒ１、２２ｒ２・・・）を基板長手方向に沿って設けてある。導電パターン２２ｑと２２ｒは、共に基板長手方向の複数個所で分断されており、導電パターン２２ｑと導電パターン２２ｒの間には発熱抵抗体２９ｂ（２９ｂ１、２９ｂ２・・・）が接続されている。２２ｅ１は給電用コネクタを接続する電極である（他端側の電極の図示は省略してある）。 However, the shape of the heat generation block disclosed in Patent Document 1 has been found by subsequent studies to be insufficient as an effect of suppressing heat generation distribution unevenness. FIG. 12 shows a part of this heater. 22a is an elongated substrate, and conductive patterns 29q (22q1, 22q2...) And conductive patterns 29r (22r1, 22r2...) Are provided on the substrate along the longitudinal direction of the substrate. The conductive patterns 22q and 22r are both divided at a plurality of positions in the longitudinal direction of the substrate, and a heating resistor 29b (29b1, 29b2,...) Is connected between the conductive pattern 22q and the conductive pattern 22r. 22e1 is an electrode for connecting a power feeding connector (illustration of the electrode on the other end side is omitted).
図１２に示すように発熱ブロックの形状を平行四辺形にして、記録紙上の任意の点が必ず発熱抵抗体２９ｂの存在する領域を通過するようにしても、ヒータ長手方向で発熱抵抗体がオーバーラップしている領域Ｂには電流があまり流れない。なぜなら、オーバーラップしている領域Ｂ以外の領域に図１２に示すように最短電流経路が存在し、電流の多くはこの最短電流経路を流れてしまうからである。発熱量は電流の二乗に比例するので、流れる電流量が少ない領域の発熱量は低下してしまい、ヒータ長手方向における発熱分布ムラを抑制する効果は小さくなってしまう。このように発熱分布ムラが大きいと画像の加熱ムラが生じてしまう。また、一つの発熱ブロック内においても、電流が流れやすい領域と流れにくい領域が存在してしまうと、上述と同様に発熱分布ムラの課題が生じる。 As shown in FIG. 12, even if the shape of the heat generation block is a parallelogram and an arbitrary point on the recording paper always passes through the region where the heat generation resistor 29b exists, the heat generation resistor is overrun in the longitudinal direction of the heater. The current does not flow so much in the wrapping region B. This is because the shortest current path exists in a region other than the overlapping region B as shown in FIG. 12, and most of the current flows through this shortest current path. Since the heat generation amount is proportional to the square of the current, the heat generation amount in the region where the flowing current amount is small decreases, and the effect of suppressing the heat generation unevenness in the heater longitudinal direction becomes small. Thus, if the heat generation distribution unevenness is large, uneven heating of the image occurs. In addition, if a region where current easily flows and a region where current does not flow easily exist in one heat generating block, a problem of uneven heat generation occurs as described above.
上述の課題を解決するための本発明は、基板と、前記基板上に設けられている第１発熱ブロックと、前記基板の長手方向において前記第１発熱ブロックが設けられた位置とは異なる前記基板上の位置に設けられている第２発熱ブロックと、前記基板の長手方向において前記第１発熱ブロック及び前記第２ブロックが設けられた位置とは異なる前記基板上の位置に設けられている第３発熱ブロックと、を有し、前記第１、第２、及び第３発熱ブロックは、各々、前記基板の一方の長辺から他方の長辺に向う方向において、第１の導電体と、前記第１の導電体に接続されている発熱抵抗体と、前記発熱抵抗体に接続されている第２の導電体と、をこの順に有しており、前記第１、第２、及び第３発熱ブロック夫々の前記第１の導電体、前記発熱抵抗体、前記第２の導電体は全て、前記基板の前記長手方向と前記基板の短手方向の両方向に対して傾斜して設けられており、前記第２発熱ブロックの前記第１の導電体の前記基板の前記長手方向における一方の端部側の第１の端部が、前記第１発熱ブロックの前記第２の導電体の前記基板の前記長手方向における他方の端部側の第２の端部のみと接続されていることにより、前記第１発熱ブロックから前記第２発熱ブロックへ流れる電流が前記第１発熱ブロックの前記第２の導電体の前記第２の端部から前記第２発熱ブロックの前記第１導電体の前記第１の端部を通過するルートのみとなるように前記第１発熱ブロックと前記第２発熱ブロックが電気的に接続されており、前記第３発熱ブロックの前記第１の導電体の前記基板の前記長手方向における前記一方の端部側の第１の端部が、前記第２発熱ブロックの前記第２の導電体の前記基板の前記長手方向における前記他方の端部側の第２の端部のみと接続されていることにより、前記第２発熱ブロックから前記第３発熱ブロックへ流れる電流が前記第２発熱ブロックの前記第２の導電体の前記第２の端部から前記第３発熱ブロックの前記第１導電体の前記第１の端部を通過するルートのみとなるように前記第２発熱ブロックと前記第３発熱ブロックが電気的に接続されていることを特徴とする。 The present invention for solving the above-described problems includes a substrate, a first heat generation block provided on the substrate, and the substrate different from the position where the first heat generation block is provided in the longitudinal direction of the substrate. A second heat generating block provided at an upper position and a third heat generating block provided at a position on the substrate different from a position at which the first heat generating block and the second block are provided in the longitudinal direction of the substrate. It has a heating block, wherein the first, second, and third heating blocks, each in one of a direction toward the other long side from the long side of the substrate, a first conductor, said first A heating resistor connected to the first conductor and a second conductor connected to the heating resistor in this order, and the first, second, and third heating blocks. Each of the first conductor and the exothermic resistor And the second conductor are all inclined with respect to both the longitudinal direction of the substrate and the short direction of the substrate, and the first conductor of the second heat generating block is provided. A first end on one end side in the longitudinal direction of the substrate is a second end on the other end side in the longitudinal direction of the second conductor of the first heat generating block. By being connected only to the portion , the current flowing from the first heat generation block to the second heat generation block causes the second heat generation block from the second end of the second conductor of the first heat generation block. The first heat generation block and the second heat generation block are electrically connected so that only a route passing through the first end of the first conductor of the first conductor is formed. The longitudinal direction of the substrate of one conductor The first end portion on the one end portion side of the second heat generating block is connected only to the second end portion on the other end portion side in the longitudinal direction of the substrate of the second conductor of the second heat generating block. As a result, the current flowing from the second heat generation block to the third heat generation block flows from the second end of the second conductor of the second heat generation block to the first heat generation block. The second heat generation block and the third heat generation block are electrically connected so that only a route passing through the first end portion of the conductor is provided.
本発明によれば、ヒータ長手方向における発熱分布ムラを抑えることができる。 According to the present invention, uneven heat generation distribution in the heater longitudinal direction can be suppressed.
図１は像加熱装置としての定着装置６の断面図である。定着装置６は、筒状のフィルム（エンドレスベルト）２３と、フィルム２３の内面に接触するヒータ２２と、フィルム２３を介してヒータ２２と共に定着ニップ部Ｎを形成する加圧ローラ（ニップ部形成部材）２４と、を有する。フィルムのベース層の材質は、ポリイミド等の耐熱樹脂、またはステンレス等の金属である。加圧ローラ２４は、鉄やアルミニウム等の材質の芯金２４ａと、シリコーンゴム等の材質の弾性層２４ｂ、ＰＦＡ等の材質の離型層２４ｃを有する。ヒータ２２は耐熱樹脂製の保持部材２１に保持されている。保持部材２１はフィルム２３の回転を案内するガイド機能も有している。加圧ローラ２４はモータＭから動力を受けて矢印ｂ方向に回転する。加圧ローラ２４が回転することによってフィルム２３が従動して回転する。 FIG. 1 is a sectional view of a fixing device 6 as an image heating device. The fixing device 6 includes a cylindrical film (endless belt) 23, a heater 22 that contacts the inner surface of the film 23, and a pressure roller (nip part forming member) that forms a fixing nip N together with the heater 22 via the film 23. 24). The material of the base layer of the film is a heat resistant resin such as polyimide, or a metal such as stainless steel. The pressure roller 24 includes a cored bar 24a made of iron or aluminum, an elastic layer 24b made of silicone rubber or the like, and a release layer 24c made of PFA or the like. The heater 22 is held by a holding member 21 made of heat resistant resin. The holding member 21 also has a guide function for guiding the rotation of the film 23. The pressure roller 24 receives power from the motor M and rotates in the arrow b direction. When the pressure roller 24 rotates, the film 23 is driven and rotated.
ヒータ２２は、セラミック製のヒータ基板２２ａと、基板２２ａ上に形成された発熱抵抗体２２ｂと、導電パターン（導電体）２２ｃ及び２２ｄと、発熱抵抗体２２ｂ及び導電パターン２２ｃ及び２２ｄを覆う絶縁性（本実施例ではガラス）の表面保護層２２ｆを有する。ヒータ基板２２ａの裏面側にはサーミスタ等の温度検知素子２２ｇが当接している。温度検知素子２２ｇの検知温度に応じて商用交流電源から発熱抵抗体２２ｂへ供給する電力が制御される。未定着トナー画像を担持する記録材は、定着ニップ部Ｎで挟持搬送されつつ加熱されて定着処理される。 The heater 22 includes a ceramic heater substrate 22a, a heating resistor 22b formed on the substrate 22a, conductive patterns (conductors) 22c and 22d, and an insulating property that covers the heating resistor 22b and the conductive patterns 22c and 22d. It has a surface protective layer 22f (glass in this embodiment). A temperature detection element 22g such as a thermistor is in contact with the back side of the heater substrate 22a. The power supplied from the commercial AC power source to the heating resistor 22b is controlled according to the temperature detected by the temperature detecting element 22g. The recording material carrying the unfixed toner image is heated and fixed while being nipped and conveyed at the fixing nip N.
次に、本実施例１のヒータ２２の形状及び特性について図２及び図３に基づき説明する。本実施例のヒータでは、基板２２ａとして幅１２ｍｍ、長さ２８０ｍｍ、厚さ０．６ｍｍの窒化アルミニウム基板を使用した。発熱抵抗体２２ｂ（２２ｂ１〜２２ｂ１３）は、酸化ルテニウム（ＲｕＯ２）、銀・パラジウム（Ａｇ・Ｐｄ）を主たる導電成分とする、特性がＮＴＣの発熱抵抗体である。また、ヒータ２２は、基板２２ａ上に基板長手方向に沿って設けられている第１導電パターン（第１導電体）２２ｃ（２２ｃ１〜２２ｃ６）と、基板２２ａ上に第１導電パターン２２ｃとは基板短手方向で異なる位置に基板長手方向に沿って設けられている第２導電パターン（第２導電体）２２ｄ（２２ｄ１〜２２ｄ６）を有する。発熱抵抗体２２ｂは第１導電パターン２２ｃと第２導電パターン２２ｄの間に接続されている。２２ｅ１、２２ｅ２は電力を供給するためのコネクタが接続される電極である。Ｓは記録材の搬送方向を示している。 Next, the shape and characteristics of the heater 22 according to the first embodiment will be described with reference to FIGS. In the heater of this example, an aluminum nitride substrate having a width of 12 mm, a length of 280 mm, and a thickness of 0.6 mm was used as the substrate 22a. The heat generating resistor 22b (22b1 to 22b13) is a heat generating resistor having a characteristic of NTC having ruthenium oxide (RuO 2 ) and silver / palladium (Ag · Pd) as main conductive components. The heater 22 includes a first conductive pattern (first conductor) 22c (22c1 to 22c6) provided on the substrate 22a along the longitudinal direction of the substrate, and the first conductive pattern 22c on the substrate 22a. A second conductive pattern (second conductor) 22d (22d1 to 22d6) is provided along the longitudinal direction of the substrate at different positions in the short direction. The heating resistor 22b is connected between the first conductive pattern 22c and the second conductive pattern 22d. 22e1 and 22e2 are electrodes to which connectors for supplying power are connected. S indicates the conveyance direction of the recording material.
図３に示すように、第１導電パターン２２ｃと第２導電パターン２２ｄは、いずれも基板長手方向に複数本に分割されている。また、発熱抵抗体２２ｂは第１導電パターン２２ｃと第２導電パターン２２ｄの間に並列に複数本接続されている。本実施例では第１導電パターン２２ｃと第２導電パターン２２ｄは、いずれも６本に分割されている。第１導電パターン２２ｃの一部である第１導電パターン２２ｃ１と、第２導電パターン２２ｄの一部である第２導電パターン２２ｄ１の間には１３本の発熱抵抗体２２ｂ１〜２２ｂ１３が電気的に並列に接続されており、第１の発熱ブロックＨ１を形成している。また、第２導電パターン２２ｄ１と第１導電パターン２２ｃ２の間にも１３本の発熱抵抗体２２ｂ１〜２２ｂ１３が電気的に並列に接続されており、第２の発熱ブロックＨ２を形成している。本実施例のヒータでは、同様にして発熱ブロックが合計１１個（Ｈ１〜Ｈ１１）形成されており、１１個の発熱ブロック（Ｈ１〜Ｈ１１）は電気的に直列に接続されている。このようにヒータ２２は発熱ブロックを複数有する構成となっている。 As shown in FIG. 3, each of the first conductive pattern 22c and the second conductive pattern 22d is divided into a plurality of pieces in the substrate longitudinal direction. A plurality of heating resistors 22b are connected in parallel between the first conductive pattern 22c and the second conductive pattern 22d. In the present embodiment, each of the first conductive pattern 22c and the second conductive pattern 22d is divided into six. Thirteen heating resistors 22b1 to 22b13 are electrically in parallel between the first conductive pattern 22c1 which is a part of the first conductive pattern 22c and the second conductive pattern 22d1 which is a part of the second conductive pattern 22d. And the first heat generation block H1 is formed. In addition, 13 heat generating resistors 22b1 to 22b13 are also electrically connected in parallel between the second conductive pattern 22d1 and the first conductive pattern 22c2 to form a second heat generating block H2. Similarly, in the heater of this embodiment, a total of 11 heat generating blocks (H1 to H11) are formed, and the 11 heat generating blocks (H1 to H11) are electrically connected in series. As described above, the heater 22 has a plurality of heat generating blocks.
次に、発熱抵抗体２２ｂの形状について説明する。図３に示すように各発熱ブロック中の１３本の発熱抵抗体２２ｂ１〜２２ｂ１３の形状は、いずれも平行四辺形である。そして、図３（ａ）に示すように、各発熱抵抗体中の最短電流経路は記録材搬送方向Ｓに対して斜めに傾いており、且つ、各発熱抵抗体の最短電流経路は、隣り合う発熱抵抗体の最短電流経路に対して基板長手方向でオーバーラップしている。図３（ａ）のＷ１が発熱抵抗体２２ｂ２の最短電流経路の基板長手方向における領域を示しており、Ｗ２が発熱抵抗体２２ｂ２の隣の発熱抵抗体２２ｂ３の最短電流経路の基板長手方向における領域を示している。領域Ｗ１と領域Ｗ２が基板長手方向においてオーバーラップしていることが判る。発熱抵抗体２２ｂの形状をこのように設計すると、記録材搬送方向Ｓに対して平行にヒータを見たときに、ヒータの長手方向に亘って最短電流経路が隙間無く存在する。よって、記録材が定着ニップ部Ｎを通過する時、記録材上の任意の点は、電流が流れて発熱する領域を必ず通過するので、記録材上のトナー像が部分的に加熱不足となる現象を抑えることができる。 Next, the shape of the heating resistor 22b will be described. As shown in FIG. 3, the 13 heating resistors 22b1 to 22b13 in each heating block are all parallelograms. As shown in FIG. 3A, the shortest current paths in the respective heating resistors are inclined with respect to the recording material transport direction S, and the shortest current paths of the respective heating resistors are adjacent to each other. It overlaps in the substrate longitudinal direction with respect to the shortest current path of the heating resistor. In FIG. 3A, W1 indicates a region in the substrate longitudinal direction of the shortest current path of the heating resistor 22b2, and W2 indicates a region in the substrate longitudinal direction of the shortest current path of the heating resistor 22b3 adjacent to the heating resistor 22b2. Is shown. It can be seen that the region W1 and the region W2 overlap in the substrate longitudinal direction. When the shape of the heating resistor 22b is designed in this way, when the heater is viewed in parallel to the recording material conveyance direction S, the shortest current path exists without a gap in the longitudinal direction of the heater. Therefore, when the recording material passes through the fixing nip portion N, an arbitrary point on the recording material always passes through a region where current flows and generates heat, so that the toner image on the recording material is partially underheated. The phenomenon can be suppressed.
次に、記録材搬送方向Ｓに対して平行にヒータを見たときに、ヒータの長手方向に亘って最短電流経路が隙間無く存在する場合の発熱抵抗体の形状に関して詳しく説明する。なお、ヒータ長手方向において最短電流経路が隙間無く存在する範囲は、像加熱装置或いは画像形成装置で使用可能な最大サイズとして設定されている定型の記録材の幅設けてあればよい。 Next, the shape of the heating resistor when the heater is viewed in parallel with the recording material conveyance direction S and the shortest current path exists in the longitudinal direction of the heater with no gap will be described in detail. It should be noted that the range in which the shortest current path exists in the longitudinal direction of the heater without any gap may be provided by the width of the standard recording material set as the maximum size that can be used in the image heating apparatus or the image forming apparatus.
図３（ｂ）に示すヒータの部分的平面図において、平行四辺形の発熱抵抗体２２ｂの長辺長さをｇ１、短辺長さをｃ１、一つの発熱ブロック中の隣り合う発熱抵抗体２２ｂの間隔をｅ１、発熱抵抗体２２ｂの傾斜角度をβ１とする。この場合、発熱抵抗体２２ｂの形状及び隙間ｅ１を（式１）で表される関係に設定すれば、各発熱抵抗体の最短電流経路が、隣り合う発熱抵抗体の最短電流経路に対して基板長手方向でオーバーラップする関係を形成できる。
ｇ１×ｃｏｓ（β１）≧ｃ１＋ｅ１ （式１）
In the partial plan view of the heater shown in FIG. 3B, the long side length of the parallelogram heating resistor 22b is g1, the short side length is c1, and the adjacent heating resistors 22b in one heating block. E1 and the inclination angle of the heating resistor 22b is β1. In this case, if the shape of the heating resistor 22b and the gap e1 are set to the relationship represented by (Equation 1), the shortest current path of each heating resistor is a substrate with respect to the shortest current path of the adjacent heating resistor. A relationship that overlaps in the longitudinal direction can be formed.
g1 × cos (β1) ≧ c1 + e1 (Formula 1)
また、隣り合う二つの発熱ブロックの境界を形成している２本の発熱抵抗体（例えば発熱ブロックＨ１の発熱抵抗体２２ｂ１３と、発熱ブロックＨ２の発熱抵抗体２２ｂ１）の関係も（式２）を満たすように設定すればよい。
ｇ１×ｃｏｓ（β１）≧ｃ１＋ｄ１ （式２）
Further, the relationship between two heating resistors (for example, the heating resistor 22b13 of the heating block H1 and the heating resistor 22b1 of the heating block H2) forming the boundary between two adjacent heating blocks is also expressed by the following equation (2). What is necessary is just to set so that it may satisfy | fill.
g1 × cos (β1) ≧ c1 + d1 (Formula 2)
本実施例のヒータは、ｅ１＝ｄ１に設定してある。なお、本実施例のヒータにおける各部位の寸法は以下の通りである。ヒータ基板の短手方向の幅ａ１は１２ｍｍ、発熱抵抗体２２ｂの基板短手方向の幅ｂ１は５ｍｍ、発熱抵抗体２２ｂの長辺ｇ１は６．２８ｍｍ、短辺ｃ１は１．４ｍｍである。傾斜角度β１は約５２．８°、隣り合う導電パターン２２ｄ間の距離ｄ１（隣り合う導電パターン２２ｃ間の距離もｄ１である）は０．５ｍｍ、一つの発熱ブロック内の隣り合う発熱抵抗体間の距離ｅ１は０．５ｍｍ、導電パターン２２ｃ及び２２ｄの基板短手方向の幅ｆ１は１．５ｍｍである。なお、発熱抵抗体２２ｂを設けた領域のヒータ長手方向の総幅は２３７ｍｍである。これらの値を（式１）に当てはめると、ｇ１×ｃｏｓ（β１）≒３．８、ｃ１＋ｅ１＝１．９となり、（式１）が成り立つ。また、ｃ１＋ｄ１＝１．９なので（式２）も成り立つ。 In the heater of this embodiment, e1 = d1 is set. In addition, the dimension of each site | part in the heater of a present Example is as follows. The width a1 in the short side direction of the heater substrate is 12 mm, the width b1 in the short side direction of the heating resistor 22b is 5 mm, the long side g1 of the heating resistor 22b is 6.28 mm, and the short side c1 is 1.4 mm. The inclination angle β1 is about 52.8 °, the distance d1 between adjacent conductive patterns 22d (the distance between adjacent conductive patterns 22c is also d1), 0.5 mm, and between adjacent heating resistors in one heating block The distance e1 is 0.5 mm, and the width f1 of the conductive patterns 22c and 22d in the short-side direction of the substrate is 1.5 mm. The total width in the heater longitudinal direction of the region where the heating resistor 22b is provided is 237 mm. When these values are applied to (Expression 1), g1 × cos (β1) ≈3.8 and c1 + e1 = 1.9 are satisfied, and (Expression 1) is established. Since c1 + d1 = 1.9, (Expression 2) also holds.
本実施例では、発熱抵抗体２２ｂの温度抵抗係数（ＴＣＲ：Ｔｅｍｐｅｒａｔｕｒｅ Ｃｏｅｆｆｉｃｉｅｎｔ ｏｆ Ｒｅｓｉｓｔａｎｃｅ）が−４５５ｐｐｍ／℃、即ちＮＴＣとなるペースト材料を用い、ヒータの総抵抗値が２０Ωとなるように導電パターンや発熱抵抗体の形状を設定した。ここで述べるＴＣＲは、一般的に高温側のＴＣＲ値として用いられる２５℃〜１２５℃間の数値である。 In this embodiment, a paste material having a temperature resistance coefficient (TCR: Temperature Coefficient of Resistance) of the heating resistor 22b of −455 ppm / ° C., that is, NTC is used, and the conductive pattern and the resistance of the heater are set to 20Ω. The shape of the heating resistor was set. The TCR described here is a numerical value between 25 ° C. and 125 ° C. that is generally used as a TCR value on the high temperature side.
以上のように、一つの発熱ブロック中の発熱抵抗体の形状を、基板長手方向において幅広くするのではなく基板短手方向に細長くして並列接続することによって、最短電流経路を短手方向Ｓに対して傾けることができる。この構成に加えて、各発熱抵抗体の最短電流経路が、隣り合う発熱抵抗体の最短電流経路に対して基板長手方向においてオーバーラップするように配置することで、基板長手方向におけるヒータの発熱分布ムラを小さく抑えることが出来る。 As described above, the shape of the heating resistor in one heating block is not widened in the longitudinal direction of the substrate, but is elongated in the lateral direction of the substrate and connected in parallel, thereby making the shortest current path in the lateral direction S. Can be tilted. In addition to this configuration, by arranging the shortest current path of each heating resistor to overlap the shortest current path of adjacent heating resistors in the substrate longitudinal direction, the heat generation distribution of the heater in the substrate longitudinal direction Unevenness can be reduced.
図４〜図６を用いて実施例２のヒータを説明する。図４に示すように実施例２のヒータ２２は、発熱抵抗体２５ｂの形状が実施例１で示した平行四辺形形状ではなく長方形であり、導電パターン２５ｃ及び２５ｄの形状も実施例１と異なっている。発熱抵抗体２５ｂ、導電パターン２５ｃ及び２５ｄ以外の、基板２２ａ、給電用電極２２ｅ１及び２２ｅ２は、それぞれ実施例１と同様の材料、形状にて形成した。なお、発熱抵抗体２５ｂを設けた領域のヒータ長手方向の総幅は２３７ｍｍである。また、総抵抗値が実施例１と同じ２０Ωになるように材料や混合比を調整して発熱抵抗体２５ｂを形成し、２５℃〜１２５℃におけるＴＣＲは−４３０ｐｐｍ／℃であった。 The heater according to the second embodiment will be described with reference to FIGS. As shown in FIG. 4, in the heater 22 of the second embodiment, the shape of the heating resistor 25b is not the parallelogram shape shown in the first embodiment but a rectangle, and the shapes of the conductive patterns 25c and 25d are also different from the first embodiment. ing. The substrate 22a and the power feeding electrodes 22e1 and 22e2 other than the heating resistor 25b and the conductive patterns 25c and 25d were formed of the same material and shape as in Example 1, respectively. The total width in the heater longitudinal direction of the region where the heating resistor 25b is provided is 237 mm. In addition, the heating resistor 25b was formed by adjusting the materials and mixing ratio so that the total resistance value would be the same 20Ω as in Example 1, and the TCR at 25 ° C. to 125 ° C. was −430 ppm / ° C.
実施例２のヒータも実施例１のヒータ同様、発熱抵抗体２５ｂを１１個の発熱ブロックに分けている。また、一つの発熱抵抗体の最短電流経路が記録材搬送方向に対して斜めに傾くようにするため、一つの発熱ブロック中で１３個の発熱抵抗体に分割している点も実施例１と同じである。この１３個の長方形に分割された発熱抵抗体２５ｂ（２５ｂ１〜２５ｂ１３）は電気的に並列に接続されて一つの発熱ブロックを構成している。また、１３個の発熱抵抗体２５ｂの群、つまり発熱ブロックは１１個あり、１１個の発熱ブロック（Ｈ１〜Ｈ１１）は電気的に直列に接続されている。 Similarly to the heater of the first embodiment, the heater of the second embodiment also divides the heating resistor 25b into 11 heat generating blocks. Further, in order to make the shortest current path of one heating resistor obliquely incline with respect to the recording material conveyance direction, it is divided into 13 heating resistors in one heating block as in the first embodiment. The same. The heat generating resistors 25b (25b1 to 25b13) divided into 13 rectangles are electrically connected in parallel to form one heat generating block. In addition, there are 11 groups of 13 heating resistors 25b, that is, 11 heating blocks, and 11 heating blocks (H1 to H11) are electrically connected in series.
本実施例では、発熱抵抗体が長方形で形成されているため、個々の発熱抵抗体２５ｂに存在する最短電流経路は単一線ではなく発熱抵抗体の全面になる。本実施例においても実施例１と同様に記録材搬送方向Ｓに対して最短電流経路が斜めに構成されている。図５（ａ）には最短電流経路の方向を示してある。実施例１のヒータよりも一つの発熱抵抗体中の最短電流経路が広いので個々の発熱抵抗体に対して２本の矢印を引いてある。また、図６に示すように、各発熱抵抗体の形状を長方形とするため、導電パターン２５ｃ及び２５ｄはΔ（デルタ）形状領域を有している。導電パターンのΔ形状領域は、発熱抵抗体を長方形にするためであれば他の形状でもよく、形状をΔに特定するものではない。 In this embodiment, since the heating resistors are formed in a rectangular shape, the shortest current path existing in each heating resistor 25b is not a single line but the entire surface of the heating resistors. Also in this embodiment, as in the first embodiment, the shortest current path is formed obliquely with respect to the recording material conveyance direction S. FIG. 5A shows the direction of the shortest current path. Since the shortest current path in one heating resistor is wider than that of the heater of the first embodiment, two arrows are drawn for each heating resistor. Further, as shown in FIG. 6, in order to make each heating resistor have a rectangular shape, the conductive patterns 25c and 25d have a Δ (delta) shape region. The Δ shape region of the conductive pattern may have another shape as long as the heating resistor is rectangular, and does not specify the shape as Δ.
本実施例のように、個々の発熱抵抗体２５ｂに存在する最短電流経路を実施例１のような単一線でなく平面にすることで、実施例１の構成に比べて、フィルム２３及び記録材への伝熱効率が向上するメリットがある。また、本実施例においても、各発熱抵抗体の最短電流経路が、隣り合う発熱抵抗体の最短電流経路に対して基板長手方向においてオーバーラップしているので、ヒータの発熱分布ムラを小さく抑えることができる。なお、図５（ａ）のＷ３が発熱抵抗体２５ｂ１の最短電流経路の基板長手方向における領域を示しており、Ｗ４が発熱抵抗体２５ｂ１の隣の発熱抵抗体２５ｂ２の最短電流経路の基板長手方向における領域を示している。領域Ｗ３と領域Ｗ４が基板長手方向においてオーバーラップしていることが判る。発熱抵抗体２５ｂの形状をこのように設計すると、記録材搬送方向Ｓに対して平行にヒータを見たときに、ヒータの長手方向に亘って最短電流経路が隙間無く存在する。よって、記録材が定着ニップ部Ｎを通過する時、記録材上の任意の点は、電流が流れて発熱する領域を必ず通過するので、記録材上のトナー像が部分的に加熱不足となる現象を抑えることができる。 As in this embodiment, the shortest current path existing in each heating resistor 25b is not a single line as in the first embodiment but a plane, so that the film 23 and the recording material are compared with the configuration of the first embodiment. There is a merit to improve heat transfer efficiency. Also in this embodiment, since the shortest current path of each heating resistor overlaps the shortest current path of adjacent heating resistors in the longitudinal direction of the substrate, the uneven heat distribution of the heater can be kept small. Can do. Note that W3 in FIG. 5A indicates a region in the substrate longitudinal direction of the shortest current path of the heating resistor 25b1, and W4 is a substrate longitudinal direction of the shortest current path of the heating resistor 25b2 adjacent to the heating resistor 25b1. The area | region in is shown. It can be seen that the region W3 and the region W4 overlap in the substrate longitudinal direction. When the shape of the heating resistor 25b is designed in this way, when the heater is viewed in parallel to the recording material conveyance direction S, the shortest current path exists without a gap along the longitudinal direction of the heater. Therefore, when the recording material passes through the fixing nip portion N, an arbitrary point on the recording material always passes through a region where current flows and generates heat, so that the toner image on the recording material is partially underheated. The phenomenon can be suppressed.
各発熱抵抗体の最短電流経路が、隣り合う発熱抵抗体の最短電流経路に対して基板長手方向においてオーバーラップ関係にするには、（式３）のように設定すればよい。
ｇ２×ｃｏｓ（β２）−ｈ２×ｃｏｓ（β２）／ｔａｎ（β２）≧ｅ２ （式３）
In order that the shortest current path of each heating resistor overlaps with the shortest current path of adjacent heating resistors in the longitudinal direction of the substrate, the following equation (3) may be set.
g2 × cos (β2) −h2 × cos (β2) / tan (β2) ≧ e2 (Formula 3)
ここで、図５（ｂ）に示すように、長方形の発熱抵抗体２５ｂの長辺長さをｇ２、短辺長さをｈ２、隣り合う発熱抵抗体２５ｂ同士の間隔をｅ２、発熱抵抗体２５ｂの傾斜角度β２とする。また、隣り合う二つの発熱ブロックの境界を形成している２本の発熱抵抗体（例えば発熱ブロックＨ１の発熱抵抗体２５ｂ１３と、発熱ブロックＨ２の発熱抵抗体２５ｂ１）の関係も（式３）のｅ２をｄ２に置き換えた（式４）を満たすように設定すればよい。
ｇ２×ｃｏｓ（β２）−ｈ２×ｃｏｓ（β２）／ｔａｎ（β２）≧ｄ２ （式４）
Here, as shown in FIG. 5B, the long side length of the rectangular heating resistor 25b is g2, the short side length is h2, the interval between the adjacent heating resistors 25b is e2, and the heating resistor 25b. The inclination angle is β2. In addition, the relationship between two heating resistors (for example, the heating resistor 25b13 of the heating block H1 and the heating resistor 25b1 of the heating block H2) forming the boundary between two adjacent heating blocks is also expressed by (Expression 3). What is necessary is just to set so that (Formula 4) may be satisfied by replacing e2 with d2.
g2 × cos (β2) −h2 × cos (β2) / tan (β2) ≧ d2 (Formula 4)
本実施例のヒータにおける各部位の寸法は以下の通りである。ヒータ基板の短手方向の幅ａ２は１２ｍｍ、発熱抵抗体２６ｂの長辺ｇ２は７．０ｍｍ、短辺ｈ２は１．０ｍｍ、傾斜角度β２は約５２．８°、発熱抵抗体間の距離ｅ２及びｄ２は０．５ｍｍとした。この数値を当てはめると、ｇ２×ｃｏｓ（β２）−ｈ２×ｃｏｓ（β２）／ｔａｎ（β２）≒３．８、ｅ２＝０．５となり（式２）が成り立つ。同様に（式４）も成り立つ。 The dimension of each part in the heater of a present Example is as follows. The width a2 in the short direction of the heater substrate is 12 mm, the long side g2 of the heating resistor 26b is 7.0 mm, the short side h2 is 1.0 mm, the inclination angle β2 is about 52.8 °, and the distance e2 between the heating resistors. And d2 was 0.5 mm. When this numerical value is applied, g2 × cos (β2) −h2 × cos (β2) / tan (β2) ≈3.8 and e2 = 0.5 (equation 2) is established. Similarly, (Expression 4) also holds.
図７及び図８を用いて実施例３のヒータを説明する。図７に示すように実施例３のヒータ２２は発熱抵抗体２６ｂを３２個の発熱ブロック（Ｈ１〜Ｈ３２）に分け、各発熱ブロック中では最短電流経路が記録材搬送方向に対して斜めになるように５本の発熱抵抗体（２６ｂ１〜２６ｂ５）に分割している。この５本の長方形に分割された発熱抵抗体２６ｂは電気的に並列に接続されている。また、３２個の発熱抵抗体２６ｂの群、つまり発熱ブロックＨ１〜Ｈ３２は電気的に直列に接続されている。図７に示すように、本実施例では、導電パターン２６ｈ１〜２６ｈ３３が基板長手方向に対して平行ではなく傾いているが、基板長手方向に沿って設けられている。発熱ブロックＨ１においては、導電パターン２６ｈ１が第１の導電体に相当し、導電パターン２６ｈ２が第２の導電体に相当する。また、発熱ブロックＨ２においては、導電パターン２６ｈ２が第１の導電体に相当し、導電パターン２６ｈ３が第２の導電体に相当する。なお、発熱抵抗体２６ｂを形成しているヒータ長手方向の総幅は２２４．２ｍｍである。発熱抵抗体２６ｂは総抵抗値が実施例１、２と同じ２０Ωになるように、材料や混合比を調整して形成し、２５℃〜１２５℃におけるＴＣＲを−４３５ｐｐｍ／℃とした。 The heater of Example 3 is demonstrated using FIG.7 and FIG.8. As shown in FIG. 7, in the heater 22 of the third embodiment, the heating resistor 26b is divided into 32 heating blocks (H1 to H32), and the shortest current path is inclined with respect to the recording material conveyance direction in each heating block. Thus, it is divided into five heating resistors (26b1 to 26b5). The heating resistors 26b divided into the five rectangles are electrically connected in parallel. Further, the group of 32 heat generating resistors 26b, that is, the heat generating blocks H1 to H32 are electrically connected in series. As shown in FIG. 7, in this embodiment, the conductive patterns 26h1 to 26h33 are not parallel to the substrate longitudinal direction but are inclined, but are provided along the substrate longitudinal direction. In the heat generation block H1, the conductive pattern 26h1 corresponds to the first conductor, and the conductive pattern 26h2 corresponds to the second conductor. In the heat generation block H2, the conductive pattern 26h2 corresponds to the first conductor, and the conductive pattern 26h3 corresponds to the second conductor. The total width in the longitudinal direction of the heater forming the heating resistor 26b is 224.2 mm. The heating resistor 26b was formed by adjusting the materials and mixing ratio so that the total resistance value was the same as that of Examples 1 and 2, and the TCR at 25 ° C. to 125 ° C. was −435 ppm / ° C.
本実施例においても発熱抵抗体が長方形で形成されているため個々の発熱抵抗体２６ｂに存在する最短電流経路は単一線ではなく発熱抵抗体全面となる。各発熱ブロック中で複数本の発熱抵抗体を並列に接続しているので、本実施の形態においても実施例１、２と同様に記録材搬送方向Ｓに対して最短電流経路が斜めに構成されている（図８（ａ））。また、各発熱抵抗体の最短電流経路が、隣り合う発熱抵抗体の最短電流経路に対して基板長手方向においてオーバーラップするように発熱抵抗体が形成されており、ヒータ長手方向における発熱分布ムラが小さく抑えられるようになっている。図８（ｂ）に示すように、本実施例のヒータにおける各部位の寸法は以下の通りである。ヒータ基板の短手方向の幅ａ３は１２ｍｍ、発熱抵抗体２６ｂの短辺ｇ３は１．３ｍｍ、長辺ｈ３は２．５ｍｍ、隣り合う発熱ブロック同士の間隔ｅ３は２．６ｍｍ、隣り合う発熱抵抗体２６ｂ同士の間隔ｅ３１は０．５ｍｍ、傾斜角度β３は３５°とした。 Also in this embodiment, since the heating resistors are formed in a rectangular shape, the shortest current path existing in each heating resistor 26b is not the single line but the entire heating resistor. Since a plurality of heat generating resistors are connected in parallel in each heat generating block, the shortest current path is configured obliquely with respect to the recording material conveyance direction S in this embodiment as in Examples 1 and 2. (FIG. 8A). In addition, the heating resistor is formed so that the shortest current path of each heating resistor overlaps the shortest current path of the adjacent heating resistor in the longitudinal direction of the substrate, and uneven heat generation distribution in the longitudinal direction of the heater is caused. It is designed to be kept small. As shown in FIG. 8B, the dimensions of each part in the heater of this example are as follows. The width a3 in the short direction of the heater substrate is 12 mm, the short side g3 of the heating resistor 26b is 1.3 mm, the long side h3 is 2.5 mm, the interval e3 between adjacent heating blocks is 2.6 mm, and the adjacent heating resistance The interval e31 between the bodies 26b was 0.5 mm, and the inclination angle β3 was 35 °.
また、最短電流経路がオーバーラップしている点を視覚的に現したのが図８（ａ）である。Ｗ５は発熱抵抗体２６ｂ１の最短電流経路の基板長手方向における領域、同様にＷ６は発熱抵抗体２６ｂ１の隣の発熱抵抗体２６ｂ２の基板長手方向における領域を示している。図８（ａ）より明らかなように、隣り合う発熱抵抗体の最短電流経路が基板長手方向でオーバーラップしているので、記録材搬送方向Ｓに対して平行にヒータを見たときに、ヒータの長手方向に亘って最短電流経路が必ず存在する構成となっている。また、隣り合う二つの発熱ブロックの境界を形成している２本の発熱抵抗体（例えば発熱ブロックＨ１の発熱抵抗体２６ｂ５と、発熱ブロックＨ２の発熱抵抗体２６ｂ１）の関係も、互いの最短電流経路がオーバーラップする関係になっている。 Further, FIG. 8A visually shows the point where the shortest current paths overlap. W5 represents a region in the substrate longitudinal direction of the shortest current path of the heating resistor 26b1, and W6 represents a region in the substrate longitudinal direction of the heating resistor 26b2 adjacent to the heating resistor 26b1. As is clear from FIG. 8A, since the shortest current paths of adjacent heating resistors overlap in the longitudinal direction of the substrate, when the heater is viewed in parallel to the recording material conveyance direction S, the heater The shortest current path always exists in the longitudinal direction. Further, the relationship between the two heat generating resistors (for example, the heat generating resistor 26b5 of the heat generating block H1 and the heat generating resistor 26b1 of the heat generating block H2) forming the boundary between two adjacent heat generating blocks is also the shortest current between them. The route is in an overlapping relationship.
図９及び図１０を用いて実施例４のヒータを説明する。図９に示すように実施例４のヒータ２２は、発熱抵抗体２７ｂの形状が実施例２で示した形状と同様に長方形であり、長辺の長さが実施例２の発熱抵抗体２５ｂの半分である。また、給電用電極２２ｅ１から供給される電流が、ヒータ長手方向で電極２２ｅ１が設けられた端部とは反対側のヒータ端部まで達した後に、折り返して給電用電極２２ｅ２に達するよう構成されており、発熱抵抗体が複数列設けられている所謂往復発熱パターンとなっている。このため導電パターンが基板短手方向において４列（２７ｉ、２７ｊ、２７ｍ、２７ｋ）設けられている。実施例１〜３のヒータは、二つの給電用電極がヒータ長手方向両端部に１つずつ配置されていた。これに対して本実施例の構成は、二つの給電用電極２２ｅ１及び２２ｅ２が両方ともヒータの長手方向において片側の端部にあるので、電極に接続するコネクタを１つにすることが出来るというメリットがある。 The heater of Example 4 is demonstrated using FIG.9 and FIG.10. As shown in FIG. 9, in the heater 22 of the fourth embodiment, the shape of the heating resistor 27b is rectangular similarly to the shape shown in the second embodiment, and the length of the long side is the same as that of the heating resistor 25b of the second embodiment. It is half. In addition, the current supplied from the power supply electrode 22e1 reaches the heater end opposite to the end where the electrode 22e1 is provided in the longitudinal direction of the heater, and then turns back to reach the power supply electrode 22e2. Thus, a so-called reciprocating heat generation pattern is provided in which a plurality of heating resistors are provided. For this reason, four rows (27i, 27j, 27m, 27k) of conductive patterns are provided in the short direction of the substrate. In the heaters of Examples 1 to 3, two power feeding electrodes are arranged one by one at both ends of the heater in the longitudinal direction. On the other hand, the configuration of this embodiment is advantageous in that the two power feeding electrodes 22e1 and 22e2 are both at one end in the longitudinal direction of the heater, so that one connector can be connected to the electrodes. There is.
基板２２ａは実施例１と同様の材料、形状にて形成した。なお、複数に分割された発熱抵抗体２７ｂが形成されている領域のヒータ長手方向の総幅は２３７ｍｍである。また、総抵抗値が実施例１と同じ２０Ωになるように、材料や混合比を調整して発熱抵抗体２７ｂを形成し、２５℃〜１２５℃におけるＴＣＲを−２３０ｐｐｍ／℃に設定した。 The substrate 22a was formed with the same material and shape as in Example 1. The total width in the heater longitudinal direction of the region where the heating resistor 27b divided into a plurality of portions is formed is 237 mm. Further, the heating resistor 27b was formed by adjusting the material and the mixing ratio so that the total resistance value was 20Ω, which was the same as in Example 1, and the TCR at 25 ° C. to 125 ° C. was set to −230 ppm / ° C.
なお、発熱抵抗体２７ｂをヒータ２２の長手方向に２２個の発熱ブロックに分け（１１個の発熱ブロック×１往復）、最短電流経路が記録材搬送方向に対して斜めになるよう一つの発熱ブロック中で発熱抵抗体は７個に分割（２７ｂ１〜２７ｂ７）されている。この７個の長方形に分割された発熱抵抗体２７ｂは電気的に並列に接続され、２２個の発熱ブロックＨ１〜Ｈ２２は電気的に直列に接続されている。本実施例においても、個々の発熱抵抗体が長方形で形成されているため、個々の発熱抵抗体２７ｂに存在する最短電流経路は発熱抵抗体全面になる。 The heating resistor 27b is divided into 22 heating blocks in the longitudinal direction of the heater 22 (11 heating blocks × 1 reciprocation), and one heating block so that the shortest current path is inclined with respect to the recording material conveyance direction. Among them, the heating resistor is divided into seven pieces (27b1 to 27b7). The heat generating resistors 27b divided into the seven rectangles are electrically connected in parallel, and the 22 heat generating blocks H1 to H22 are electrically connected in series. Also in this embodiment, since each heating resistor is formed in a rectangular shape, the shortest current path existing in each heating resistor 27b is the entire heating resistor.
ところで、本実施例では、上述のように、発熱ブロックが基板の短手方向において異なる位置に複数列（本実施例では二列）設けられている。そして、短手方向における一方の列の発熱ブロック内の各発熱抵抗体の最短電流経路が、他方の列の発熱ブロック内の各発熱抵抗体の最短電流経路に対して、長手方向においてオーバーラップしている。具体的には、図１０（ａ）に示すように、一つの発熱ブロック内の隣り合う二つの発熱抵抗体（例えば発熱ブロックＨ１内の発熱抵抗体２７ｂ１と発熱抵抗体２７ｂ２）の最短電流経路は基板長手方向でオーバーラップしていない。しかしながら、列が異なる発熱ブロック間で長手方向に隣り合う二つの発熱抵抗体（例えば発熱ブロックＨ１内の発熱抵抗体２７ｂ５（領域Ｗ７）と発熱ブロックＨ２２内の発熱抵抗体２７ｂ５）の最短電流経路は、基板長手方向でオーバーラップしている。このような形状でも、ヒータの長手方向における発熱分布ムラを小さく抑えることができる。 In the present embodiment, as described above, the heat generating blocks are provided in a plurality of rows (two rows in this embodiment) at different positions in the short direction of the substrate. The shortest current path of each heating resistor in the heating block of one row in the short direction overlaps the shortest current path of each heating resistor in the heating block of the other row in the longitudinal direction. ing. Specifically, as shown in FIG. 10A, the shortest current path of two adjacent heating resistors (for example, the heating resistor 27b1 and the heating resistor 27b2 in the heating block H1) in one heating block is There is no overlap in the longitudinal direction of the substrate. However, the shortest current path of two heating resistors (for example, the heating resistor 27b5 (region W7) in the heating block H1 and the heating resistor 27b5 in the heating block H22) adjacent in the longitudinal direction between the heating blocks in different columns is , Overlapping in the longitudinal direction of the substrate. Even with such a shape, it is possible to reduce the uneven heat generation distribution in the longitudinal direction of the heater.
なお、図１０（ｂ）に示すように、本実施例のヒータにおける各部位の寸法は以下の通りである。ヒータ基板２２ａの基板短手方向の幅ａ４は１２ｍｍ、発熱抵抗体２７ｂの長辺ｇ４は３．５ｍｍ、短辺ｈ４は１．０ｍｍ、傾斜角度β４は約５２．８°、７個に分割された発熱抵抗体間の距離ｅ４１は２．３ｍｍとした。発熱ブロック間の距離ｅ４も２．３ｍｍとした。 In addition, as shown in FIG.10 (b), the dimension of each site | part in the heater of a present Example is as follows. The width a4 of the heater substrate 22a in the short direction of the substrate is 12 mm, the long side g4 of the heating resistor 27b is 3.5 mm, the short side h4 is 1.0 mm, the inclination angle β4 is about 52.8 °, and is divided into seven pieces. The distance e41 between the heating resistors was 2.3 mm. The distance e4 between the heat generating blocks was also 2.3 mm.
図１１を用いて実施例５のヒータを説明する。このヒータの形状は実施例１のヒータの変形例であり、図１１に示すように、二本の導電パターン２８ｎ及び２８ｐが基板長手方向において分割されていない。したがって発熱ブロックが１つしかない形態である。導電パターン２８ｎと導電パターン２８ｐの間に並列に接続される発熱抵抗体は１４３本（２８ｂ１〜２８ｂ１４３）である。隣り合う発熱抵抗体同士の最短電流経路が基板長手方向でオーバーラップしている点は実施例１と同様である。ただし、発熱抵抗体がＮＴＣではなくＰＴＣである。ＰＴＣの材質は体積抵抗が非常に低く、実施例１のように発熱ブロックを複数個に分割する構成が有効であるが、発熱抵抗体として体積抵抗が比較的高いＰＴＣの材質を用いることができれば、本実施例の形状でも構わない。 The heater of Example 5 is demonstrated using FIG. The shape of this heater is a modification of the heater of Example 1, and as shown in FIG. 11, the two conductive patterns 28n and 28p are not divided in the substrate longitudinal direction. Therefore, there is only one heat generating block. There are 143 heating resistors (28b1 to 28b143) connected in parallel between the conductive pattern 28n and the conductive pattern 28p. Similar to the first embodiment, the shortest current paths between adjacent heating resistors overlap in the longitudinal direction of the substrate. However, the heating resistor is not PTC but PTC. The PTC material has a very low volume resistance, and it is effective to divide the heat generating block into a plurality of pieces as in the first embodiment. However, if the PTC material having a relatively high volume resistance can be used as the heat generating resistor, The shape of this embodiment may be used.
なお、上述した実施例１〜４は、発熱抵抗体としてＮＴＣのものを例に示した。しかしながら、ＰＴＣの発熱抵抗体の場合でも、その形状を実施例１〜４のように、最短電流経路をオーバーラップさせる構成にすれば基板長手方向における発熱分布ムラを小さく抑えることが出来る。 In Examples 1 to 4 described above, NTC's heating resistor is shown as an example. However, even in the case of a PTC heating resistor, if the shape is configured to overlap the shortest current paths as in the first to fourth embodiments, the heat generation unevenness in the longitudinal direction of the substrate can be kept small.
本発明は、未定着トナー像を記録材に定着する定着装置だけでなく、記録材上に定着済みのトナー像を再度加熱することによって、画像の光沢度を向上させる光沢付与装置などの像加熱装置にも適用できる。 The present invention provides not only a fixing device that fixes an unfixed toner image on a recording material, but also an image heating device such as a gloss applying device that improves the glossiness of an image by reheating the toner image that has been fixed on the recording material. It can also be applied to devices.
２２ ヒータ
２２ａ ヒータ基板
２２ｂ 発熱抵抗体
２２ｃ、２２ｄ 導電パターン
２２ｅ１、２２ｅ２ 電極
２３ フィルム
２４ 加圧ローラ
Ｐ 記録材
Ｎ 定着ニップ部
22 heater 22a heater substrate 22b heating resistor 22c, 22d conductive pattern 22e1, 22e2 electrode 23 film 24 pressure roller P recording material N fixing nip portion
Claims (4)
前記第１、第２、及び第３発熱ブロックは、各々、前記基板の一方の長辺から他方の長辺に向う方向において、第１の導電体と、前記第１の導電体に接続されている発熱抵抗体と、前記発熱抵抗体に接続されている第２の導電体と、をこの順に有しており、
前記第１、第２、及び第３発熱ブロック夫々の前記第１の導電体、前記発熱抵抗体、前記第２の導電体は全て、前記基板の前記長手方向と前記基板の短手方向の両方向に対して傾斜して設けられており、
前記第２発熱ブロックの前記第１の導電体の前記基板の前記長手方向における一方の端部側の第１の端部が、前記第１発熱ブロックの前記第２の導電体の前記基板の前記長手方向における他方の端部側の第２の端部のみと接続されていることにより、前記第１発熱ブロックから前記第２発熱ブロックへ流れる電流が前記第１発熱ブロックの前記第２の導電体の前記第２の端部から前記第２発熱ブロックの前記第１導電体の前記第１の端部を通過するルートのみとなるように前記第１発熱ブロックと前記第２発熱ブロックが電気的に接続されており、
前記第３発熱ブロックの前記第１の導電体の前記基板の前記長手方向における前記一方の端部側の第１の端部が、前記第２発熱ブロックの前記第２の導電体の前記基板の前記長手方向における前記他方の端部側の第２の端部のみと接続されていることにより、前記第２発熱ブロックから前記第３発熱ブロックへ流れる電流が前記第２発熱ブロックの前記第２の導電体の前記第２の端部から前記第３発熱ブロックの前記第１導電体の前記第１の端部を通過するルートのみとなるように前記第２発熱ブロックと前記第３発熱ブロックが電気的に接続されていることを特徴とするヒータ。 A substrate, a first heat generation block provided on the substrate, and a second heat generation block provided at a position on the substrate different from the position at which the first heat generation block is provided in the longitudinal direction of the substrate And a third heat generating block provided at a position on the substrate different from the position where the first heat generating block and the second block are provided in the longitudinal direction of the substrate ,
The first, second, and third heat generating blocks are respectively connected to the first conductor and the first conductor in a direction from one long side to the other long side of the substrate. A heating resistor and a second conductor connected to the heating resistor in this order,
The first conductor, the heating resistor, and the second conductor of each of the first, second, and third heating blocks are all in both the longitudinal direction of the substrate and the short direction of the substrate. Is inclined with respect to
The first end of the first conductor of the second heat generation block on one end side in the longitudinal direction of the substrate is the first end of the substrate of the second conductor of the first heat generation block. By being connected only to the second end on the other end side in the longitudinal direction , the current flowing from the first heat generating block to the second heat generating block is the second conductor of the first heat generating block. The first heat generation block and the second heat generation block are electrically connected so that only a route from the second end of the second heat generation block passes through the first end of the first conductor of the second heat generation block. Connected ,
The first end on the one end side in the longitudinal direction of the substrate of the first conductor of the third heat generating block is the first end of the substrate of the second conductor of the second heat generating block. By being connected only to the second end portion on the other end side in the longitudinal direction, the current flowing from the second heat generating block to the third heat generating block is the second heat generating block second current. The second heat generation block and the third heat generation block are electrically connected so that only a route from the second end portion of the conductor to the first end portion of the first conductor of the third heat generation block is provided. A heater characterized in that it is connected in a mechanical manner .
前記ヒータが請求項１〜３いずれか１項に記載のヒータであることを特徴とする像加熱装置。 An endless belt, a heater that contacts an inner surface of the endless belt, and a nip portion forming member that forms a nip portion together with the heater via the endless belt, and a recording material that carries an image at the nip portion. In an image heating apparatus for heating while nipping and conveying,
An image heating apparatus, wherein the heater is the heater according to claim 1.
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