JP4886274B2

JP4886274B2 - Fixing device

Info

Publication number: JP4886274B2
Application number: JP2005324315A
Authority: JP
Inventors: 利充武内
Original assignee: Kyocera Mita Corp
Current assignee: Kyocera Document Solutions Inc
Priority date: 2005-11-09
Filing date: 2005-11-09
Publication date: 2012-02-29
Anticipated expiration: 2025-11-09
Also published as: JP2007133053A

Description

本発明は、静電写真式の複写機、プリンタ、ファクシミリなどの画像形成装置に装着される定着装置、更に詳しくは、駆動源により回転駆動される熱定着ローラと、熱定着ローラの回転方向上流側に配置された上流側支持ローラと、該回転方向下流側に配置された下流側支持ローラと、該ローラの各々間に巻き掛けられた無端状のベルトとを備え、該ローラの各々が、該ベルトを介して熱定着ローラに押圧されかつ該ベルトと共に従動させられる形態の定着装置に関する。 The present invention relates to a fixing device mounted on an image forming apparatus such as an electrophotographic copying machine, a printer, or a facsimile, and more specifically, a heat fixing roller that is rotationally driven by a driving source, and an upstream direction of rotation of the heat fixing roller. An upstream support roller disposed on the side, a downstream support roller disposed on the downstream side in the rotational direction, and an endless belt wound around each of the rollers, each of the rollers comprising: The present invention relates to a fixing device which is pressed by a heat fixing roller through the belt and driven together with the belt.

画像形成装置に装着される定着装置は、未定着トナーを用紙に定着させるため、高い温度と一定時間の圧力を必要としている。特に近年、ニーズが多くなってきているカラー画像形成装置においては、多色のトナーを重ねて印字するため、モノクロ機よりも高い熱量と圧力が必要とされる。この要求に応えるためには、熱定着ローラと圧ローラとのニップ幅が大きい定着装置が有利であるが、ニップ幅を更に大きくするためには、加圧側に無端ベルトを使用する、いわゆるベルトニップ式の定着装置が更に有利である。ベルト式定着装置としては、駆動源により回転駆動される熱定着ローラと、４個の支持ローラと、支持ローラの各々間に巻き掛けられた無端状のベルトとを備え、２個の支持ローラが、該ベルトを介して熱定着ローラに圧接されかつ該ベルトと共に従動させられるよう構成されたものがすでに開示されている（特許文献１参照）。 A fixing device mounted on an image forming apparatus requires high temperature and pressure for a certain time in order to fix unfixed toner on a sheet. In particular, in recent years, color image forming apparatuses, which have been in increasing demand, require a higher amount of heat and pressure than monochrome machines in order to print multiple color toners. In order to meet this requirement, a fixing device having a large nip width between the heat fixing roller and the pressure roller is advantageous, but in order to further increase the nip width, an endless belt is used on the pressure side, so-called belt nip. A fixing device of the type is further advantageous. The belt-type fixing device includes a heat fixing roller that is rotationally driven by a drive source, four support rollers, and an endless belt wound around each of the support rollers. There is already disclosed a structure in which the belt is pressed against the heat fixing roller via the belt and driven together with the belt (see Patent Document 1).

図５は、上記形態の定着装置の構成を模式図として概略的に示したもので、以下、該定着装置について更に詳細に説明する。図５に示された定着装置は、駆動源である電動モータＭにより、図５において時計方向に回転駆動される熱定着ローラ２と、熱定着ローラ２の半径方向外側において相互に周方向に間隔をおいて配置された上流側支持ローラ４及び下流側支持ローラ６と、上流側支持ローラ４及び下流側支持ローラ６間に巻き掛けられた無端状のベルト８とを備えている。上流側支持ローラ４は、熱定着ローラ２の回転方向上流側に配置され、下流側支持ローラ６は、熱定着ローラ２の回転方向下流側に配置されている。上流側及び下流側支持ローラ４及び６は、後の説明から容易に理解されるように、それぞれ、熱定着ローラ２に対し、該ベルト８を介して押圧され、該ベルト８の外周面における一部領域は、熱定着ローラ２の外周面における一部領域に押圧される。 FIG. 5 schematically shows the configuration of the fixing device of the above embodiment as a schematic diagram. The fixing device will be described in more detail below. The fixing device shown in FIG. 5 is spaced circumferentially between the heat fixing roller 2 that is driven to rotate clockwise in FIG. 5 by the electric motor M that is a driving source, and on the radially outer side of the heat fixing roller 2. The upstream side support roller 4 and the downstream side support roller 6 that are disposed at a distance from each other, and the endless belt 8 that is wound between the upstream side support roller 4 and the downstream side support roller 6. The upstream support roller 4 is disposed upstream of the heat fixing roller 2 in the rotation direction, and the downstream support roller 6 is disposed downstream of the heat fixing roller 2 in the rotation direction. The upstream and downstream support rollers 4 and 6 are each pressed against the heat fixing roller 2 via the belt 8 so as to be easily understood from the following description. The partial area is pressed against a partial area on the outer peripheral surface of the heat fixing roller 2.

図５と共に図６を参照して更に説明する。熱定着ローラ２は、アルミニウムなどの金属からなる円筒状本体１０と、円筒状本体１０の外周面に配設された、シリコンゴムなどの弾性材からなる弾性層１２とを備えている。弾性層１２は、該外周面の全領域を、実質的に一定の厚みで覆うよう配設されている。熱定着ローラ２の円筒状本体１０の両端には、円筒状本体１０よりも小径の円筒状の軸部１４が、両端から軸方向の両側に延び出すよう一体に形成されている。熱定着ローラ２の軸部１４の各々は、定着装置の、図示しない一対の側壁に、それぞれ図示しない軸受を介して回転自在に支持される。熱定着ローラ２の中心部には熱源であるハロゲンヒータＨが配設されている。ハロゲンヒータＨの両端部は、定着装置の該側壁の各々の外側に離脱自在に装着される側カバー（不図示）に、静止状態で支持される。 Further description will be given with reference to FIG. 6 together with FIG. The heat fixing roller 2 includes a cylindrical main body 10 made of a metal such as aluminum, and an elastic layer 12 made of an elastic material such as silicon rubber and disposed on the outer peripheral surface of the cylindrical main body 10. The elastic layer 12 is disposed so as to cover the entire area of the outer peripheral surface with a substantially constant thickness. At both ends of the cylindrical main body 10 of the heat fixing roller 2, cylindrical shaft portions 14 having a smaller diameter than the cylindrical main body 10 are integrally formed so as to extend from both ends to both sides in the axial direction. Each of the shaft portions 14 of the heat fixing roller 2 is rotatably supported by a pair of side walls (not shown) of the fixing device via bearings (not shown). A halogen heater H as a heat source is disposed at the center of the heat fixing roller 2. Both ends of the halogen heater H are supported in a stationary state by side covers (not shown) that are detachably mounted on the outsides of the side walls of the fixing device.

上流側支持ローラ４及び下流側支持ローラ６は、それぞれ、相互に実質的に同じ構成を有しているので、それらを代表して、上流側支持ローラ４の構成について説明する。上流側支持ローラ４の構成は、特許文献１には開示されていないが、一般的には、直径が実質的に一定の円形外周面を有する金属部材１６を備えている。アルミニウムなどの金属から構成される金属部材１６は、円柱状本体１８と、円柱状本体１８の両端から軸方向の両側に延び出す軸部２０とから構成することができる。軸部２０の各々は、円柱状本体１８よりも小径である。円柱状本体１８の外周面には、シリコンゴムなどの弾性材からなる弾性層２２が、該外周面の全領域を、実質的に一定の厚みで覆うよう配設される。 Since the upstream side support roller 4 and the downstream side support roller 6 have substantially the same configuration, the configuration of the upstream side support roller 4 will be described as a representative. The configuration of the upstream support roller 4 is not disclosed in Patent Document 1, but generally includes a metal member 16 having a circular outer peripheral surface having a substantially constant diameter. The metal member 16 composed of a metal such as aluminum can be composed of a columnar body 18 and a shaft portion 20 extending from both ends of the columnar body 18 to both sides in the axial direction. Each of the shaft portions 20 has a smaller diameter than the columnar body 18. An elastic layer 22 made of an elastic material such as silicon rubber is disposed on the outer peripheral surface of the columnar body 18 so as to cover the entire area of the outer peripheral surface with a substantially constant thickness.

上流側支持ローラ４及び下流側支持ローラ６の軸部２０の各々は、それぞれ、定着装置の、対応する側壁に形成された長穴２４に、相対回転可能にかつ長穴２４に沿って摺動可能に嵌合・支持される。長穴２４の各々は、熱定着ローラ２を軸方向に見て、熱定着ローラ２の軸心を通る図示しない仮想直線に平行な２本の図示しない仮想直線に沿って延在するよう形成されている。 Each of the shaft portions 20 of the upstream side support roller 4 and the downstream side support roller 6 is slidable along the long hole 24 so as to be relatively rotatable in a long hole 24 formed in the corresponding side wall of the fixing device. It is possible to fit and support. Each of the long holes 24 is formed to extend along two imaginary straight lines (not shown) parallel to a phantom straight line (not shown) passing through the axial center of the heat fixing roller 2 when the heat fixing roller 2 is viewed in the axial direction. ing.

上流側及び下流側支持ローラ４及び６における軸部２０の各々は、それぞれ、半円状の軸受部を有する軸受部材２６に回転自在に支持され、軸受部材２６の各々と、対応する該側板との間には、圧縮コイルばね２８が配設されている。圧縮コイルばね２８の各々は、対応する軸受部材２６を、熱定着ローラ２に向けて押圧している。圧縮コイルばね２８の各々の押圧方向は、熱定着ローラ２を軸方向に見て、熱定着ローラ２の軸心を通る上記仮想直線に平行な２本の上記仮想直線に沿って熱定着ローラ２に向かう方向である。上流側及び下流側支持ローラ４及び６の外周面における周方向の一部領域は、ベルト８を介して、熱定着ローラ２の外周面における周方向の一部領域に押圧される。ベルト８の外周面における周方向の一部領域は、熱定着ローラ２の外周面における周方向の一部領域に押圧される。熱定着ローラ２の円筒状本体１０、弾性層１２、上流側及び下流側支持ローラ４及び６の円柱状本体１８、弾性層２２及び該ベルト８の各々の幅（図６において左右方向の幅であって、相互に平行な熱定着ローラ２、上流側及び下流側支持ローラ４及び６の軸方向における幅）は、相互に実質的に同じでありかつ、最大通紙幅Ｗよりも広い。ベルト８は、ポリイミド樹脂から形成されている。 Each of the shaft portions 20 in the upstream and downstream support rollers 4 and 6 is rotatably supported by a bearing member 26 having a semicircular bearing portion, and each of the bearing members 26 and the corresponding side plate A compression coil spring 28 is disposed between them. Each of the compression coil springs 28 presses the corresponding bearing member 26 toward the heat fixing roller 2. Each pressing direction of the compression coil spring 28 is viewed along the two virtual straight lines parallel to the virtual straight line passing through the axial center of the heat fixing roller 2 when the heat fixing roller 2 is viewed in the axial direction. It is the direction toward. A partial region in the circumferential direction on the outer peripheral surfaces of the upstream and downstream support rollers 4 and 6 is pressed against a partial region in the circumferential direction on the outer peripheral surface of the heat fixing roller 2 via the belt 8. A partial region in the circumferential direction on the outer peripheral surface of the belt 8 is pressed against a partial region in the circumferential direction on the outer peripheral surface of the heat fixing roller 2. The width of the cylindrical main body 10 of the heat fixing roller 2, the elastic layer 12, the columnar main body 18 of the upstream and downstream support rollers 4 and 6, the elastic layer 22 and the belt 8 (the width in the horizontal direction in FIG. 6). The axial widths of the heat fixing roller 2 and the upstream and downstream support rollers 4 and 6 parallel to each other are substantially the same and wider than the maximum sheet passing width W. The belt 8 is made of a polyimide resin.

熱定着ローラ２が電動モータＭにより図５において時計方向に回転駆動されると、上流側及び下流側支持ローラ４及び６は、ベルト８と共に反時計方向に従動回転させられる。ハロゲンヒータＨが通電され、発熱が開始されると、熱定着ローラ２の昇温が開始される。熱定着ローラ２に伝達された熱は、ベルト８及び、ベルト８を介して上流側及び下流側支持ローラ４及び６にも伝達される。熱定着ローラ２の表面温度が常温から所定の温度に達した後、片面（上面）にトナーが転写された用紙Ｐが図５において右から左に向かって搬送され、熱定着ローラ２とベルト８とのニップ領域を通過すると、用紙Ｐの片面に転写された未定着トナーは、熱定着ローラ２によって用紙Ｐの片面に溶融定着される。 When the heat fixing roller 2 is rotated in the clockwise direction in FIG. 5 by the electric motor M, the upstream and downstream support rollers 4 and 6 are driven to rotate counterclockwise together with the belt 8. When the halogen heater H is energized and heat generation is started, the temperature of the heat fixing roller 2 is increased. The heat transmitted to the heat fixing roller 2 is also transmitted to the upstream side and downstream side support rollers 4 and 6 via the belt 8 and the belt 8. After the surface temperature of the heat fixing roller 2 reaches a predetermined temperature from room temperature, the sheet P on which the toner is transferred on one side (upper surface) is conveyed from right to left in FIG. The unfixed toner transferred on one side of the paper P is melted and fixed on one side of the paper P by the heat fixing roller 2.

上記形態の定着装置によれば、ベルト８の外周面における周方向の一部領域が熱定着ローラ２の外周面における周方向の一部領域にニップされるので、ニップ幅が、熱定着ローラと圧ローラとから形成されるニップ幅に較べて大幅に拡大される。その結果、用紙Ｐに十分な熱と圧力を与えることができるので、定着性を向上させることができる。 According to the fixing device of the above aspect, a partial region in the circumferential direction on the outer peripheral surface of the belt 8 is nipped by a partial region in the circumferential direction on the outer peripheral surface of the heat fixing roller 2. The nip width formed from the pressure roller is greatly enlarged. As a result, since sufficient heat and pressure can be applied to the paper P, the fixability can be improved.

ところで、上記形態の定着装置によりトナー画像が定着される用紙Ｐには、普通紙のほかに、ＯＨＰシート（ＯＨＰフィルム）、封筒などがある。ＯＨＰシートは、普通紙に較べて、表面が平滑でトナーが浸透しにくい合成樹脂製のフィルムから形成されているので、該ニップ領域において幅方向（搬送方向に直交する水平幅方向）における圧力が均一でなく（換言すれば、搬送力が均一でなく）、圧力にムラがあると（換言すれば、搬送力にムラがあると）、それに対応してトナーの溶融ムラ、すなわち画像乱れが発生するおそれがある。他方、封筒は、空気を介在した、比較的幅の狭い２枚の紙による二重構造であるため、該ニップ領域における圧力にムラがあると、上面側と下面側との間の搬送力の差が大きくなる、空気の抜け方が不均一となる、などの現象により、しわが発生しやすくなる。 Incidentally, the paper P on which the toner image is fixed by the fixing device of the above-described form includes, in addition to plain paper, an OHP sheet (OHP film), an envelope, and the like. Since the OHP sheet is made of a synthetic resin film that has a smooth surface and is less likely to penetrate toner compared to plain paper, the pressure in the width direction (horizontal width direction perpendicular to the conveying direction) is reduced in the nip region. If the pressure is not uniform (in other words, the transport force is not uniform) and the pressure is uneven (in other words, the transport force is uneven), the toner melts unevenly, that is, the image is disturbed. There is a risk. On the other hand, since the envelope has a double structure with two sheets of paper having a relatively narrow width with air interposed therebetween, if the pressure in the nip region is uneven, the conveyance force between the upper surface side and the lower surface side is reduced. Wrinkles are likely to occur due to phenomena such as a large difference and uneven air escape.

上記定着装置においては、先に述べたように、それぞれ一定の厚さで軸方向に直線状に延在する、上流側及び下流側支持ローラ４及び６の弾性層２２及び熱定着ローラ２の弾性層１２がベルト８を介して相対的に押圧されかつ、上流側及び下流側支持ローラ４及び６の両端から突出した軸部２０の各々を介して熱定着ローラ２に向う方向の力が付与されることに起因して、上流側及び下流側支持ローラ４及び６と熱定着ローラ２との間の、ベルト８を介した圧接力は、両端領域においては比較的高く、両端領域から中央領域に向って徐々に低くなるような圧力分布となる。すなわち、通紙領域においては、幅方向に不均一な圧力分布が形成される。 In the fixing device, as described above, the elastic layers 22 of the upstream and downstream support rollers 4 and 6 and the elasticity of the heat fixing roller 2 each extending linearly in the axial direction with a certain thickness. A force in a direction toward the heat fixing roller 2 is applied through each of the shaft portions 20 that the layer 12 is relatively pressed through the belt 8 and protrudes from both ends of the upstream and downstream support rollers 4 and 6. As a result, the pressure contact force between the upstream and downstream support rollers 4 and 6 and the heat fixing roller 2 via the belt 8 is relatively high in both end regions, and from the both end regions to the central region. The pressure distribution becomes gradually lower. That is, a non-uniform pressure distribution is formed in the width direction in the paper passing area.

熱定着ローラ２は、用紙Ｐが搬入されない場合には、押圧されたベルト８を直接搬送する（移動させる）。しかし、用紙Ｐが搬入された場合には、用紙Ｐの両側においては直接ベルト８を移動させるが、中間領域においては、用紙Ｐを介してベルト８を移動させることになる。このように、中間領域においては、ベルト８を搬送させる力として用紙Ｐが利用されるので、用紙Ｐに作用する圧接力が、先に述べたように幅方向に不均一であると（圧力ムラがあると）、ＯＨＰシートにおいては、該圧力ムラに対応して、トナーの溶融ムラ、すなわち画像乱れが発生するおそれがある。また封筒においては、空気を介在した、２枚の紙による二重構造であるため、封筒に作用する圧接力は、封筒が存在しない領域における圧接力に較べて過剰に高くなる。その結果、上面側と下面側との間の搬送力の差が大きくなる、空気の抜け方が不均一となる、などの現象により、しわが発生しやすくなる。このような不具合は、特に熱定着ローラ２と上流側支持ローラ４との、ベルト８を介したニップ部において発生しやすい。
特開平０８−２０２１８０号公報 The heat fixing roller 2 directly conveys (moves) the pressed belt 8 when the paper P is not carried in. However, when the paper P is carried in, the belt 8 is directly moved on both sides of the paper P, but the belt 8 is moved via the paper P in the intermediate region. In this way, in the intermediate region, the paper P is used as a force for transporting the belt 8, so that the pressure contact force acting on the paper P is uneven in the width direction as described above (pressure unevenness). In the case of the OHP sheet, there is a possibility that uneven melting of the toner, that is, image disturbance may occur corresponding to the pressure unevenness. Further, since the envelope has a double structure using two sheets of paper with air interposed therebetween, the pressure contact force acting on the envelope is excessively higher than the pressure contact force in a region where no envelope is present. As a result, wrinkles are likely to occur due to phenomena such as an increase in the difference in conveying force between the upper surface side and the lower surface side, and uneven air escape. Such a problem is likely to occur particularly in the nip portion between the heat fixing roller 2 and the upstream support roller 4 via the belt 8.
Japanese Patent Laid-Open No. 08-202180

本発明の目的は、ＯＨＰシートのトナー溶融ムラによる画像乱れ及び封筒におけるしわの発生を防止することを可能にする、新規な定着装置を提供することである。 An object of the present invention is to provide a novel fixing device that can prevent image distortion due to toner melting unevenness of an OHP sheet and generation of wrinkles in an envelope.

本発明の一局面によれば、
駆動源により回転駆動されかつ金属部材の外周面が弾性層により覆われるよう構成された熱定着ローラと、熱定着ローラの回転方向上流側に配置された上流側支持ローラと、該回転方向下流側に配置された下流側支持ローラと、該ローラの各々間に巻き掛けられた無端状のベルトとを備え、該ローラの各々が、該ベルトを介して熱定着ローラに押圧されかつ該ベルトと共に従動させられる定着装置において、上流側支持ローラの両端領域と、該両端領域に対応する、熱定着ローラの両端領域との間の、該ベルトを介した両端領域圧接力は、上流側支持ローラの該両端領域間の中間領域と、該中間領域に対応する、熱定着ローラの該両端領域間の中間領域との間の、該ベルトを介した中間領域圧接力よりも大きく、上流側支持ローラの該中間領域の幅は、最大通紙幅よりも広く形成され、上流側支持ローラは、相互に同じ直径の外周面を有する両端領域と、該両端領域よりも小さな直径の外周面を有する、該両端領域間の中間領域とを有する金属部材と；金属部材の該中間領域を覆うよう配設された弾性層と；を備え、
上流側支持ローラの該両端領域は、金属部材の該両端領域からなり、上流側支持ローラの該中間領域は、金属部材の該中間領域を覆う弾性層の領域からなり、かつ該中間領域を覆う弾性層の領域の外周面の直径は金属部材の該両端領域の外周面の直径と同じである、ことを特徴とする定着装置、が提供される。
本発明の他の局面によれば、
駆動源により回転駆動されかつ金属部材の外周面が弾性層により覆われるよう構成された熱定着ローラと、熱定着ローラの回転方向上流側に配置された上流側支持ローラと、該回転方向下流側に配置された下流側支持ローラと、該ローラの各々間に巻き掛けられた無端状のベルトとを備え、該ローラの各々が、該ベルトを介して熱定着ローラに押圧されかつ該ベルトと共に従動させられる定着装置において、上流側支持ローラの両端領域と、該両端領域に対応する、熱定着ローラの両端領域との間の、該ベルトを介した両端領域圧接力は、上流側支持ローラの該両端領域間の中間領域と、該中間領域に対応する、熱定着ローラの該両端領域間の中間領域との間の、該ベルトを介した中間領域圧接力よりも大きく、上流側支持ローラの該中間領域の幅は、最大通紙幅よりも広く形成され、上流側支持ローラは、相互に同じ直径の外周面を有する両端領域と、該両端領域よりも小さな直径の外周面を有する、該両端領域間の中間領域とを有する金属部材と；金属部材の該両端領域の外周面及び該中間領域の外周面を覆うよう配設された弾性層と；を備え、弾性層の外周面の直径は一定であり、上流側支持ローラの該両端領域は、金属部材の該両端領域を覆う弾性層の領域からなり、上流側支持ローラの該中間領域は、金属部材の該中間領域を覆う弾性層の領域からなる、ことを特徴とする定着装置、が提供される。
本発明の更に他の局面によれば、
駆動源により回転駆動されかつ金属部材の外周面が弾性層により覆われるよう構成された熱定着ローラと、熱定着ローラの回転方向上流側に配置された上流側支持ローラと、該回転方向下流側に配置された下流側支持ローラと、該ローラの各々間に巻き掛けられた無端状のベルトとを備え、該ローラの各々が、該ベルトを介して熱定着ローラに押圧されかつ該ベルトと共に従動させられる定着装置において、上流側支持ローラの両端領域と、該両端領域に対応する、熱定着ローラの両端領域との間の、該ベルトを介した両端領域圧接力は、上流側支持ローラの該両端領域間の中間領域と、該中間領域に対応する、熱定着ローラの該両端領域間の中間領域との間の、該ベルトを介した中間領域圧接力よりも大きく、上流側支持ローラの該中間領域の幅は、最大通紙幅よりも広く形成され、上流側支持ローラは、直径が一定の外周面を有する金属部材と、金属部材の外周面を一定の厚みで覆うよう配設された弾性層とを備え、弾性層の外周面の直径は一定であり、弾性層の両端領域における硬度は、弾性層の該両端領域間の中間領域における硬度よりも硬く、上流側支持ローラの該両端領域は、弾性層の該両端領域からなり、上流側支持ローラの該中間領域は、弾性層の該中間領域からなる、ことを特徴とする定着装置、が提供される。 According to one aspect of the present invention,
A heat fixing roller that is rotationally driven by a drive source and is configured so that the outer peripheral surface of the metal member is covered with an elastic layer; an upstream support roller that is disposed upstream in the rotation direction of the heat fixing roller; and a downstream side in the rotation direction A downstream support roller disposed on the roller, and an endless belt wound around each of the rollers, each of the rollers being pressed against the heat fixing roller via the belt and driven together with the belt In the fixing device to be caused, the both end region pressure contact force via the belt between the both end regions of the upstream support roller and the both end regions of the heat fixing roller corresponding to the both end regions is the same as that of the upstream support roller. The intermediate region pressure contact force between the intermediate region between the two end regions and the intermediate region between the two end regions of the heat fixing roller corresponding to the intermediate region is larger than the intermediate region pressing force via the belt, and the upstream support roller Middle territory The width is wide rather than the maximum paper width, the upstream support roller has both end regions having an outer peripheral surface of the same diameter to one another, the outer peripheral surface of smaller diameter than the both end region, between the both end region A metal member having an intermediate region of; and an elastic layer disposed to cover the intermediate region of the metal member;
The both end regions of the upstream support roller are composed of the both end regions of the metal member, and the intermediate region of the upstream support roller is composed of an elastic layer region covering the intermediate region of the metal member and covers the intermediate region. There is provided a fixing device characterized in that the diameter of the outer peripheral surface of the elastic layer region is the same as the diameter of the outer peripheral surface of the both end regions of the metal member .
According to another aspect of the invention,
A heat fixing roller that is rotationally driven by a drive source and is configured so that the outer peripheral surface of the metal member is covered with an elastic layer; an upstream support roller that is disposed upstream in the rotation direction of the heat fixing roller; and a downstream side in the rotation direction A downstream support roller disposed on the roller, and an endless belt wound around each of the rollers, each of the rollers being pressed against the heat fixing roller via the belt and driven together with the belt In the fixing device to be caused, the both end region pressure contact force via the belt between the both end regions of the upstream support roller and the both end regions of the heat fixing roller corresponding to the both end regions is the same as that of the upstream support roller. The intermediate region pressure contact force between the intermediate region between the two end regions and the intermediate region between the two end regions of the heat fixing roller corresponding to the intermediate region is larger than the intermediate region pressing force via the belt, and the upstream support roller Middle territory The width is wider than the maximum paper width, the upstream support roller, both ends region having an outer peripheral surface of the same diameter to one another, than the both end region having an outer peripheral surface of smaller diameter, between the both end region and the metal member and an intermediate region; and an elastic layer disposed to cover the outer peripheral surface of the outer peripheral surface and the intermediate region of the both end region of the metal member; with a diameter of the outer circumferential surface of the elastic layer is in a constant And the both end regions of the upstream support roller are made of elastic layer regions covering the both end regions of the metal member, and the intermediate region of the upstream support roller is made of the elastic layer region covering the intermediate region of the metal member. A fixing device characterized by the above is provided.
According to yet another aspect of the invention,
A heat fixing roller that is rotationally driven by a drive source and is configured so that the outer peripheral surface of the metal member is covered with an elastic layer; an upstream support roller that is disposed upstream in the rotation direction of the heat fixing roller; and a downstream side in the rotation direction A downstream support roller disposed on the roller, and an endless belt wound around each of the rollers, each of the rollers being pressed against the heat fixing roller via the belt and driven together with the belt In the fixing device to be caused, the both end region pressure contact force via the belt between the both end regions of the upstream support roller and the both end regions of the heat fixing roller corresponding to the both end regions is the same as that of the upstream support roller. The intermediate region pressure contact force between the intermediate region between the two end regions and the intermediate region between the two end regions of the heat fixing roller corresponding to the intermediate region is larger than the intermediate region pressing force via the belt, and the upstream support roller Middle territory The width is wider than the maximum paper width, the upstream support roller comprises a metal member having an outer peripheral surface of the constant diameter, elastic layer disposed to cover at regular thickness of the outer peripheral surface of the metal member The diameter of the outer peripheral surface of the elastic layer is constant, the hardness in the both end regions of the elastic layer is harder than the hardness in the intermediate region between the two end regions of the elastic layer, and the both end regions of the upstream support roller are There is provided a fixing device including the both end regions of the elastic layer, and the intermediate region of the upstream support roller is formed of the intermediate region of the elastic layer .

以下、本発明に従って構成された定着装置の好適な実施の形態を、添付図面を参照して詳細に説明する。 DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a fixing device configured according to the present invention will be described in detail with reference to the accompanying drawings.

先ず、図１及び図２を参照して、本発明に従って構成された定着装置の実施形態について説明する。なお、図１及び図２に示す本発明による定着装置が、図５及び図６に示す従来の定着装置と相違する構成は、上流側支持ローラ３０の構成のみであって、その他の構成は実質的に同一であるので、同一部分は同一符号で示し、説明は省略する。 First, an embodiment of a fixing device configured according to the present invention will be described with reference to FIGS. 1 and 2. The configuration of the fixing device according to the present invention shown in FIGS. 1 and 2 is different from the conventional fixing device shown in FIGS. 5 and 6 only in the configuration of the upstream support roller 30, and the other configurations are substantially the same. Therefore, the same parts are denoted by the same reference numerals, and description thereof is omitted.

上流側支持ローラ３０は、金属部材３２と弾性層３３とを備えている。アルミニウムなどの金属から構成される金属部材３２は、円柱状本体３４と、円柱状本体３４の両端から軸方向の両側に延び出す軸部３６を備えている。軸部３６の各々は、円柱状本体３４よりも小径である。円柱状本体３４は、相互に同じ直径の外周面を有する両端領域Ｗ１、Ｗ１（一端領域Ｗ１と他端領域Ｗ１とからなる両端領域Ｗ１、Ｗ１）と、両端領域Ｗ１、Ｗ１よりも小さな直径の外周面を有する、両端領域Ｗ１、Ｗ１間の中間領域Ｗ２とを有している。中間領域Ｗ２の直径は一定である。シリコンゴムなどの弾性材からなる弾性層３３は、金属部材３２の中間領域Ｗ２の全領域を覆うよう配設されている。弾性層３３の外周面の直径は、円柱状本体３４の両端領域Ｗ１、Ｗ１の外周面における直径と実質的に同じである。 The upstream support roller 30 includes a metal member 32 and an elastic layer 33. The metal member 32 made of a metal such as aluminum includes a columnar body 34 and shaft portions 36 that extend from both ends of the columnar body 34 to both sides in the axial direction. Each of the shaft portions 36 has a smaller diameter than the cylindrical main body 34. The cylindrical main body 34 has both end regions W1 and W1 (both end regions W1 and W1 composed of one end region W1 and the other end region W1) having outer peripheral surfaces having the same diameter, and a diameter smaller than both end regions W1 and W1. It has an intermediate area W2 between both end areas W1 and W1, which has an outer peripheral surface. The diameter of the intermediate region W2 is constant. The elastic layer 33 made of an elastic material such as silicon rubber is disposed so as to cover the entire area of the intermediate area W <b> 2 of the metal member 32. The diameter of the outer peripheral surface of the elastic layer 33 is substantially the same as the diameter of the outer peripheral surface of both end regions W1 and W1 of the cylindrical main body 34.

金属部材３２の円柱状本体３４における両端領域Ｗ１、Ｗ１は、上流側支持ローラ３０の両端領域Ｗ１、Ｗ１を構成し、金属部材３２の円柱状本体３４における中間領域Ｗ２を覆う弾性層３３の領域は、上流側支持ローラ３０の両端領域Ｗ１、Ｗ１間の中間領域Ｗ２を構成する。換言すれば、上流側支持ローラ３０の両端領域Ｗ１、Ｗ１は、金属部材３２の円柱状本体３４における両端領域Ｗ１、Ｗ１からなり、上流側支持ローラ３０の両端領域Ｗ１、Ｗ１間の中間領域Ｗ２は、金属部材３２の円柱状本体３４における中間領域Ｗ２を覆う弾性層３３の領域からなる。上流側支持ローラ３０の両端領域Ｗ１、Ｗ１間の中間領域Ｗ２の幅、すなわち金属部材３２の円柱状本体３４における中間領域Ｗ２の幅は、最大通紙幅Ｗよりも広い。 Both end regions W1 and W1 of the cylindrical member 34 of the metal member 32 constitute both end regions W1 and W1 of the upstream support roller 30 and a region of the elastic layer 33 that covers the intermediate region W2 of the columnar body 34 of the metal member 32. Constitutes an intermediate region W2 between both end regions W1, W1 of the upstream support roller 30. In other words, both end regions W1 and W1 of the upstream support roller 30 are composed of both end regions W1 and W1 in the cylindrical main body 34 of the metal member 32, and an intermediate region W2 between the both end regions W1 and W1 of the upstream support roller 30. Consists of a region of the elastic layer 33 covering the intermediate region W2 of the cylindrical main body 34 of the metal member 32. The width of the intermediate region W2 between both end regions W1 and W1 of the upstream support roller 30, that is, the width of the intermediate region W2 in the columnar body 34 of the metal member 32 is wider than the maximum sheet passing width W.

上記定着装置においては、先に述べたのと同じく、圧縮コイルばね２８の各々により、上流側支持ローラ３０が、ベルト８を介して熱定着ローラ２に押圧される。圧縮コイルばね２８の各々による押圧力は、上流側支持ローラ３０における軸部３６の各々を介して付与される。上流側支持ローラ３０の両端領域Ｗ１、Ｗ１は、金属部材３２の円柱状本体３４の外周面からなり、上流側支持ローラ３０の中間領域Ｗ２は、金属部材３２の円柱状本体３４における中間領域Ｗ２を覆う弾性層３３の外周面からなる。このような構成に起因して、上流側支持ローラ３０の両端領域Ｗ１、Ｗ１（すなわち金属部材３２の円柱状本体３４の外周面からなる両端領域Ｗ１、Ｗ１）と、両端領域Ｗ１、Ｗ１に対応する、熱定着ローラ２の両端領域との間の、ベルト８を介した両端領域圧接力は、上流側支持ローラ３０の中間領域Ｗ２と、中間領域Ｗ２に対応する、熱定着ローラ２の該両端領域間の中間領域との間の、ベルト８を介した中間領域圧接力よりも大きい。 In the fixing device, the upstream support roller 30 is pressed against the heat fixing roller 2 via the belt 8 by each of the compression coil springs 28 as described above. The pressing force by each of the compression coil springs 28 is applied via each of the shaft portions 36 in the upstream support roller 30. Both end regions W1 and W1 of the upstream support roller 30 are composed of the outer peripheral surface of the columnar body 34 of the metal member 32, and the intermediate region W2 of the upstream support roller 30 is the intermediate region W2 of the columnar body 34 of the metal member 32. It consists of the outer peripheral surface of the elastic layer 33 which covers. Due to such a configuration, both end regions W1 and W1 of the upstream support roller 30 (that is, both end regions W1 and W1 formed of the outer peripheral surface of the columnar body 34 of the metal member 32) correspond to both end regions W1 and W1. The both end region pressing force between the both end regions of the heat fixing roller 2 via the belt 8 is the intermediate region W2 of the upstream support roller 30 and the both ends of the heat fixing roller 2 corresponding to the intermediate region W2. It is larger than the intermediate region pressure contact force via the belt 8 between the intermediate regions between the regions.

上記定着装置において、熱定着ローラ２と上流側支持ローラ３０との、ベルト８を介したニップ部（正確には、該ニップ部における熱定着ローラ２とベルト８との間）にＯＨＰシート（不図示）が搬入された場合には、ＯＨＰシートは、中間領域Ｗ２における弾性層３３と、熱定着ローラ２の、対応する弾性層１２（図１）との間に沈み込んで搬送されるが、
ベルト８は、上記両端領域Ｗ１、Ｗ１において、上流側支持ローラ３０における金属部材３２の円柱状本体３４の外周面が、ベルト８を介して熱定着ローラ２の弾性層１２に押圧されているので、両端領域Ｗ１、Ｗ１においてしっかりと搬送される。その結果、ベルト８を搬送する力としてＯＨＰシートが実質的に利用されず、中間領域圧接力が、一端から他端にわたってほぼ一定となる（幅方向に均一な圧力分布となる）ので、ベルト８の搬送力とＯＨＰシートの搬送力とに差が生じにくく、ＯＨＰシートに作用する圧力はほぼ均一となりかつ直進させられるので、トナーの溶融ムラ、すなわち画像乱れが発生することはない。また、該ニップ部に封筒（不図示）が搬入された場合には、上面側と下面側との間の搬送力の差がほとんど無くなるので、しわの発生が防止される。 In the above fixing device, an OHP sheet (non-fixed) is placed in the nip portion between the heat fixing roller 2 and the upstream support roller 30 via the belt 8 (more precisely, between the heat fixing roller 2 and the belt 8 in the nip portion). When the OHP sheet is carried in, the OHP sheet is submerged and conveyed between the elastic layer 33 in the intermediate region W2 and the corresponding elastic layer 12 (FIG. 1) of the heat fixing roller 2.
In the belt 8, the outer peripheral surface of the cylindrical main body 34 of the metal member 32 in the upstream support roller 30 is pressed against the elastic layer 12 of the heat fixing roller 2 via the belt 8 in the both end regions W1 and W1. The two end regions W1 and W1 are securely conveyed. As a result, the OHP sheet is not substantially used as a force for conveying the belt 8, and the intermediate region pressure contact force is substantially constant from one end to the other end (a uniform pressure distribution in the width direction). Therefore, the difference between the transport force of the toner and the transport force of the OHP sheet is hardly generated, and the pressure acting on the OHP sheet is almost uniform and is made to advance straight, so that toner melting unevenness, that is, image disturbance does not occur. Further, when an envelope (not shown) is carried into the nip portion, the difference in conveying force between the upper surface side and the lower surface side is almost eliminated, so that generation of wrinkles is prevented.

図３には、本発明に従って構成された定着装置の他の実施形態の要部が示されている。図３に示す本発明による定着装置が、図１及び図２に示す定着装置と相違する構成は、上流側支持ローラ４０の構成のみであって、その他の構成は実質的に同一であるので、同一部分は同一符号で示し、説明は省略する。 FIG. 3 shows a main part of another embodiment of the fixing device constructed according to the present invention. The fixing device according to the present invention shown in FIG. 3 differs from the fixing device shown in FIGS. 1 and 2 only in the configuration of the upstream support roller 40, and the other configurations are substantially the same. The same parts are denoted by the same reference numerals, and description thereof is omitted.

上流側支持ローラ４０は、金属部材４２と弾性層４３とを備えている。アルミニウムなどの金属から構成される金属部材４２は、円柱状本体４４と、円柱状本体４４の両端から軸方向の両側に延び出す軸部４６を備えている。軸部４６の各々は、円柱状本体４４よりも小径である。円柱状本体４４は、相互に同じ直径の外周面を有する両端領域Ｗ１、Ｗ１（一端領域Ｗ１と他端領域Ｗ１とからなる両端領域Ｗ１、Ｗ１）と、両端領域Ｗ１、Ｗ１よりも小さな直径の外周面を有する、両端領域Ｗ１、Ｗ１間の中間領域Ｗ２とを有している。中間領域Ｗ２の直径は一定である。シリコンゴムなどの弾性体からなる弾性層４３は、金属部材４２の両端領域Ｗ１、Ｗ１の外周面及び中間領域Ｗ２の外周面を覆うよう配設される。弾性層４３の外周面の直径は実質的に一定である。 The upstream support roller 40 includes a metal member 42 and an elastic layer 43. The metal member 42 made of a metal such as aluminum includes a columnar body 44 and shaft portions 46 extending from both ends of the columnar body 44 to both sides in the axial direction. Each of the shaft portions 46 has a smaller diameter than the cylindrical main body 44. The cylindrical main body 44 has both end regions W1 and W1 (both end regions W1 and W1 composed of one end region W1 and the other end region W1) having outer peripheral surfaces having the same diameter, and a smaller diameter than both end regions W1 and W1. It has an intermediate area W2 between both end areas W1 and W1, which has an outer peripheral surface. The diameter of the intermediate region W2 is constant. The elastic layer 43 made of an elastic body such as silicon rubber is disposed so as to cover the outer peripheral surfaces of both end regions W1, W1 and the intermediate region W2 of the metal member 42. The diameter of the outer peripheral surface of the elastic layer 43 is substantially constant.

金属部材４２の円柱状本体４４における両端領域Ｗ１、Ｗ１を覆う弾性層４３の領域は、上流側支持ローラ４０の両端領域Ｗ１、Ｗ１を構成し、金属部材４２の中間領域Ｗ２を覆う弾性層４３の領域は、上流側支持ローラ４０の中間領域Ｗ２を構成する。換言すれば、上流側支持ローラ４０の両端領域は、金属部材４２の両端領域Ｗ１、Ｗ１を覆う弾性層４３の領域からなり、上流側支持ローラ４０の中間領域は、金属部材４２の中間領域Ｗ２を覆う弾性層４３の領域からなる。上流側支持ローラ４０の両端領域Ｗ１、Ｗ１間の中間領域Ｗ２の幅、すなわち金属部材４２の円柱状本体４４における中間領域Ｗ２の幅は、最大通紙幅Ｗよりも広い。 The region of the elastic layer 43 covering both end regions W1 and W1 in the cylindrical main body 44 of the metal member 42 constitutes both end regions W1 and W1 of the upstream support roller 40 and covers the intermediate region W2 of the metal member 42. This region constitutes an intermediate region W2 of the upstream support roller 40. In other words, both end regions of the upstream support roller 40 are formed by the elastic layer 43 region covering both end regions W1, W1 of the metal member 42, and the intermediate region of the upstream support roller 40 is the intermediate region W2 of the metal member 42. It consists of the area | region of the elastic layer 43 which covers. The width of the intermediate region W2 between both end regions W1 and W1 of the upstream support roller 40, that is, the width of the intermediate region W2 in the cylindrical main body 44 of the metal member 42 is wider than the maximum sheet passing width W.

この定着装置においては、上流側支持ローラ４０の両端領域Ｗ１、Ｗ１における弾性層４３の厚みが比較的薄く（例えば０．５ｍｍ）、中間領域Ｗ２における弾性層４３の厚みが比較的厚く（例えば２．０ｍｍ）形成されているので、上流側支持ローラ４０の両端領域Ｗ１、Ｗ１と中間領域Ｗ２における、弾性層４３の変形力の差により、ベルト８の搬送力が変化する。すなわち、上流側支持ローラ３０の両端領域Ｗ１、Ｗ１（弾性層４３の厚みが比較的薄い領域）と、両端領域Ｗ１、Ｗ１に対応する、熱定着ローラ２の両端領域との間の、ベルト８を介した両端領域圧接力が、上流側支持ローラ３０の中間領域Ｗ２（弾性層４３の厚みが比較的厚い領域）と、中間領域Ｗ２に対応する、熱定着ローラ２の該両端領域間の中間領域との間の、ベルト８を介した中間領域圧接力よりも大きくなる。その結果、中間領域Ｗ２においては、熱定着ローラ２とＯＨＰシート又は封筒との密着性が保持され、両端領域Ｗ１、Ｗ１においては、ベルト８を介して熱定着ローラ２と上流側支持ローラ４０との密着性が保持されるので、図１及び図２を参照して説明した先の実施形態と、実質的に同じ効果を得ることができる。 In this fixing device, the thickness of the elastic layer 43 in both end regions W1 and W1 of the upstream support roller 40 is relatively thin (for example, 0.5 mm), and the thickness of the elastic layer 43 in the intermediate region W2 is relatively thick (for example, 2). 0.0 mm), the conveying force of the belt 8 changes due to the difference in the deformation force of the elastic layer 43 in the both end regions W1, W1 and the intermediate region W2 of the upstream support roller 40. That is, the belt 8 between the both end regions W1 and W1 (the region where the elastic layer 43 is relatively thin) of the upstream support roller 30 and the both end regions of the heat fixing roller 2 corresponding to the both end regions W1 and W1. The intermediate area W2 between the both ends of the heat fixing roller 2 corresponding to the intermediate area W2 and the intermediate area W2 of the upstream support roller 30 corresponding to the intermediate area W2 It becomes larger than the intermediate | middle area | region press-contact force via the belt 8 between the area | regions. As a result, in the intermediate area W2, the adhesion between the heat fixing roller 2 and the OHP sheet or envelope is maintained, and in both end areas W1 and W1, the heat fixing roller 2 and the upstream support roller 40 are connected via the belt 8. Therefore, substantially the same effect as the previous embodiment described with reference to FIGS. 1 and 2 can be obtained.

図４には、本発明に従って構成された定着装置の他の実施形態の要部が示されている。図４に示す本発明による定着装置が、図１及び図２に示す定着装置と相違する構成は、上流側支持ローラ５０の構成のみであって、その他の構成は実質的に同一であるので、同一部分は同一符号で示し、説明は省略する。 FIG. 4 shows a main part of another embodiment of the fixing device constructed according to the present invention. The fixing device according to the present invention shown in FIG. 4 is different from the fixing device shown in FIGS. 1 and 2 only in the configuration of the upstream support roller 50 and the other configurations are substantially the same. The same parts are denoted by the same reference numerals, and description thereof is omitted.

上流側支持ローラ５０は、金属部材５２と弾性層５３とを備えている。アルミニウムなどの金属から構成される金属部材５２は、外周面の直径が一定の円柱状本体５４と、円柱状本体５４の両端から軸方向の両側に延び出す軸部５６を備えている。軸部５６の各々は、円柱状本体５４よりも小径である。シリコンゴムなどの弾性体からなる弾性層５３は、円柱状本体５４の外周面の全領域を実質的に一定の厚みで覆うよう配設されている。弾性層５３の外周面の直径は実質的に一定である。弾性層５３の両端領域Ｗ１、Ｗ１における硬度は、弾性層５３の両端領域Ｗ１、Ｗ１間の中間領域Ｗ２における硬度よりも硬い。弾性層５３の両端領域Ｗ１、Ｗ１は、上流側支持ローラ５０の両端領域Ｗ１、Ｗ１を構成し、弾性層５３の中間領域Ｗ２は、上流側支持ローラ５０の中間領域Ｗ２を構成する。換言すれば、上流側支持ローラ５０の両端領域は、弾性層５３の両端領域Ｗ１、Ｗ１からなり、上流側支持ローラ５０の中間領域Ｗ２は、弾性層５３の中間領域Ｗ２からなる。上流側支持ローラ５０の両端領域Ｗ１、Ｗ１間の中間領域Ｗ２の幅、すなわち金属部材５２の円柱状本体５４における中間領域Ｗ２の幅は、最大通紙幅Ｗよりも広い。 The upstream support roller 50 includes a metal member 52 and an elastic layer 53. The metal member 52 made of a metal such as aluminum includes a columnar body 54 having a constant outer peripheral diameter, and a shaft portion 56 that extends from both ends of the columnar body 54 to both sides in the axial direction. Each of the shaft portions 56 has a smaller diameter than the cylindrical main body 54. The elastic layer 53 made of an elastic body such as silicon rubber is disposed so as to cover the entire outer peripheral surface of the cylindrical main body 54 with a substantially constant thickness. The diameter of the outer peripheral surface of the elastic layer 53 is substantially constant. The hardness in the both end regions W1 and W1 of the elastic layer 53 is harder than the hardness in the intermediate region W2 between the both end regions W1 and W1 of the elastic layer 53. Both end regions W1 and W1 of the elastic layer 53 constitute both end regions W1 and W1 of the upstream support roller 50, and an intermediate region W2 of the elastic layer 53 constitutes an intermediate region W2 of the upstream support roller 50. In other words, both end regions of the upstream support roller 50 are composed of both end regions W1 and W1 of the elastic layer 53, and an intermediate region W2 of the upstream support roller 50 is composed of an intermediate region W2 of the elastic layer 53. The width of the intermediate region W2 between both end regions W1 and W1 of the upstream support roller 50, that is, the width of the intermediate region W2 in the cylindrical main body 54 of the metal member 52 is wider than the maximum sheet passing width W.

この定着装置においては、金属部材５２の円柱状本体５４の、直径が一定の外周面が、一定の厚さの弾性層５３により全領域にわたって覆われている。そして、弾性層５３の両端領域Ｗ１、Ｗ１の硬度は、比較的硬く（例えば、ＪＩＳ−Ａ：４０）、弾性層５３の中間領域Ｗ２の硬度はかなり柔らかく（例えば、ＪＩＳ−Ａ：５）形成されている。その結果、図１〜図３を参照して説明した先の二つの実施形態におけるのと実質的に同じ効果を得ることができる。 In this fixing device, the outer peripheral surface having a constant diameter of the cylindrical main body 54 of the metal member 52 is covered over the entire region by the elastic layer 53 having a constant thickness. And the hardness of the both ends area | regions W1 and W1 of the elastic layer 53 is comparatively hard (for example, JIS-A: 40), and the hardness of the intermediate | middle area | region W2 of the elastic layer 53 is quite soft (for example, JIS-A: 5) formation. Has been. As a result, substantially the same effect as in the previous two embodiments described with reference to FIGS. 1 to 3 can be obtained.

本願発明による定着装置の上記実施形態において、上流側支持ローラ３０、４０及び５０の金属部材３２、４２及び５２における円柱状本体３４、４４及び５４は、実軸により形成されているが、中空管により形成する実施形態もある。その場合、例えば、軸部３６、４６及び５６は、中空管と同心位置を延在するよう配置され、中空管との接続は、半径方向及び軸方向に延在する複数のブリッジ部によればよい。また、下流側支持ローラ６は、上流側支持ローラ３０、４０及び５０と実質的に同じ構成でもよいが、従来における構成（図５及び図６）であってもよい。 In the above embodiment of the fixing device according to the present invention, the cylindrical main bodies 34, 44 and 54 in the metal members 32, 42 and 52 of the upstream support rollers 30, 40 and 50 are formed by solid axes, but are hollow. There is also an embodiment formed by a tube. In that case, for example, the shaft portions 36, 46 and 56 are arranged so as to extend concentrically with the hollow tube, and the connection with the hollow tube is connected to a plurality of bridge portions extending in the radial direction and the axial direction. You can do it. The downstream support roller 6 may have substantially the same configuration as the upstream support rollers 30, 40, and 50, but may have a conventional configuration (FIGS. 5 and 6).

本発明に従って構成された定着装置の実施形態の要部を示す構成概略図であって、各ローラの軸方向に見た構成概略図である。FIG. 3 is a schematic configuration diagram illustrating a main part of an embodiment of a fixing device configured according to the present invention, and is a schematic configuration diagram viewed in the axial direction of each roller. 図１に示す定着装置における、熱定着ローラと上流側支持ローラとの、ベルトを介したニップ部における断面概略図である。FIG. 2 is a schematic cross-sectional view of a nip portion between a heat fixing roller and an upstream support roller via a belt in the fixing device shown in FIG. 1. 本発明に従って構成された定着装置の他の実施形態の要部を示す断面概略図であって、図２に対応する断面概略図である。FIG. 3 is a schematic cross-sectional view showing a main part of another embodiment of the fixing device configured according to the present invention, corresponding to FIG. 2. 本発明に従って構成された定着装置の更に他の実施形態の要部を示す断面概略図であって、図２に対応する断面概略図である。FIG. 6 is a schematic cross-sectional view showing a main part of still another embodiment of a fixing device configured according to the present invention, corresponding to FIG. 2. 従来の定着装置の要部を示す構成概略図であって、各ローラの軸方向に見た構成概略図である。It is the structure schematic which shows the principal part of the conventional fixing device, Comprising: It is the structure schematic seen in the axial direction of each roller. 図５に示す定着装置における、熱定着ローラと上流側支持ローラとの、ベルトを介したニップ部における横断面概略図である。FIG. 6 is a schematic cross-sectional view of a nip portion between a heat fixing roller and an upstream support roller via a belt in the fixing device shown in FIG. 5.

Explanation of symbols

２：熱定着ローラ
４、３０、４０、５０：上流側支持ローラ
６：下流側支持ローラ
８：無端状のベルト
１０：円筒状本体
１２、２２、３３、４３、５３：弾性層
１４、２０、３６、４６、５６：軸部
１６、３２、４２、５２：金属部材
１８、３４、４４、５４：円柱状本体
２４：長穴
２６：軸受部材
２８：圧縮コイルばね
Ｈ：ハロゲンヒータ
Ｍ：電動モータ
Ｐ：用紙
Ｗ：最大通紙幅
Ｗ１、Ｗ１：両端領域
Ｗ２：中間領域 2: heat fixing rollers 4, 30, 40, 50: upstream support roller 6: downstream support roller 8: endless belt 10: cylindrical body 12, 22, 33, 43, 53: elastic layers 14, 20, 36, 46, 56: Shaft portions 16, 32, 42, 52: Metal members 18, 34, 44, 54: Columnar body 24: Long hole 26: Bearing member 28: Compression coil spring H: Halogen heater M: Electric motor P: Paper W: Maximum sheet passing width W1, W1: Both end areas W2: Intermediate area

Claims

A heat fixing roller that is rotationally driven by a drive source and is configured so that the outer peripheral surface of the metal member is covered with an elastic layer; an upstream support roller that is disposed upstream in the rotation direction of the heat fixing roller; and a downstream side in the rotation direction A downstream support roller disposed on the roller, and an endless belt wound around each of the rollers, each of the rollers being pressed against the heat fixing roller via the belt and driven together with the belt In the fixing device to be
The both end region pressure contact force via the belt between the both end regions of the upstream support roller and the both end regions of the heat fixing roller corresponding to the both end regions is an intermediate region between the both end regions of the upstream support roller. And an intermediate region pressure contact force through the belt between the intermediate region between the both end regions of the heat fixing roller corresponding to the intermediate region,
Width of the intermediate region of the upstream support roller is formed widely than the maximum sheet width,
The upstream support roller includes a metal member having both end regions having outer peripheral surfaces having the same diameter, and an intermediate region between the both end regions having an outer peripheral surface having a smaller diameter than the both end regions; An elastic layer disposed to cover the intermediate region;
The both end regions of the upstream support roller are composed of the both end regions of the metal member, and the intermediate region of the upstream support roller is composed of an elastic layer region covering the intermediate region of the metal member and covers the intermediate region. The diameter of the outer peripheral surface of the region of the elastic layer is the same as the diameter of the outer peripheral surface of the both end regions of the metal member.
A fixing device.

A heat fixing roller that is rotationally driven by a drive source and is configured so that the outer peripheral surface of the metal member is covered with an elastic layer; an upstream support roller that is disposed upstream in the rotation direction of the heat fixing roller; and a downstream side in the rotation direction A downstream support roller disposed on the roller, and an endless belt wound around each of the rollers, each of the rollers being pressed against the heat fixing roller via the belt and driven together with the belt In the fixing device to be
The both end region pressure contact force via the belt between the both end regions of the upstream support roller and the both end regions of the heat fixing roller corresponding to the both end regions is an intermediate region between the both end regions of the upstream support roller. And an intermediate region pressure contact force through the belt between the intermediate region between the both end regions of the heat fixing roller corresponding to the intermediate region,
The width of the intermediate region of the upstream support roller is formed wider than the maximum sheet passing width ,
The upstream support roller includes a metal member having both end regions having outer peripheral surfaces having the same diameter, and an intermediate region between the both end regions having an outer peripheral surface having a smaller diameter than the both end regions; an elastic layer disposed to cover the outer peripheral surface and the outer peripheral surface of the intermediate region of the ends region; with a diameter of the outer circumferential surface of the elastic layer is a constant,
The both end regions of the upstream support roller are composed of elastic layer regions covering the both end regions of the metal member, and the intermediate region of the upstream support roller is composed of elastic layer regions covering the intermediate region of the metal member.
A fixing device.

A heat fixing roller that is rotationally driven by a drive source and is configured so that the outer peripheral surface of the metal member is covered with an elastic layer; an upstream support roller that is disposed upstream in the rotation direction of the heat fixing roller; and a downstream side in the rotation direction A downstream support roller disposed on the roller, and an endless belt wound around each of the rollers, each of the rollers being pressed against the heat fixing roller via the belt and driven together with the belt In the fixing device to be
The both end region pressure contact force via the belt between the both end regions of the upstream support roller and the both end regions of the heat fixing roller corresponding to the both end regions is an intermediate region between the both end regions of the upstream support roller. And an intermediate region pressure contact force through the belt between the intermediate region between the both end regions of the heat fixing roller corresponding to the intermediate region,
The width of the intermediate region of the upstream support roller is formed wider than the maximum sheet passing width ,
Upstream support roller comprises a metal member having an outer peripheral surface of the constant diameter, and an elastic layer of the outer peripheral surface is disposed so as to cover at regular thickness of the metal member, the diameter of the outer peripheral surface of the elastic layer constant And the hardness at both end regions of the elastic layer is harder than the hardness at the intermediate region between the both end regions of the elastic layer, and the both end regions of the upstream support roller are composed of the both end regions of the elastic layer, and the upstream support The intermediate region of the roller comprises the intermediate region of the elastic layer;
A fixing device.