JP2006267392A - Image fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt-nip system image fixing device capable of preventing irregularities in an image from occurring by the scattering of a toner image by water vapor produced from a moisture containing recording medium and thermally expanded air. <P>SOLUTION: An elastic layer 121c is provided on the rear surface side of an endless belt 121. In a gap formed between a plurality of pressuring members 122 and 125 pressing the endless belt 121 on the surface of a rotating body 111, the endless belt 121 is pressed on the surface of the rotating body 111 by the plurality of pressuring members 122 and 125, whereby the elastic layer 121c is deformed so that the thickness of the endless belt 121 may be equal to or above that of the belt 121 in a non-load state, and subject was solved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image fixing apparatus used in an image forming apparatus such as a copying machine, a printer, or a facsimile that employs an electrophotographic system, an ink jet recording system, and the like, and in particular, while conveying the sheet material while heating the sheet material. The present invention relates to an image fixing device that heats and pressurizes an unfixed toner image or an undried ink image formed thereon and fixes the toner image or ink image to a sheet material.

Japanese Patent Laid-Open No. 3-65976 JP-A-8-262903

  Conventionally, as this type of image fixing device, for example, those disclosed in Japanese Patent Laid-Open Nos. 3-65976 and 8-262903 are known. Such an image fixing device has the advantage that a relatively small and long fixing nip can be formed by pressing an endless belt stretched around a plurality of rolls against the fixing roll, and a high fixing speed can be realized. .

  More specifically, the fixing device according to Japanese Patent Laid-Open No. 3-65976 has a fixing sheet sandwiched between a fixing roller having a heat source therein and the fixing roller stretched between a pair of rollers. An endless belt for conveying, and the endless belt is configured as an endless belt unit in which the roller shaft end sides of the pair of rollers are rotatably supported by one roller support plate on each side, Further, each roller support plate can be rotated around a pivot point provided between one roller shaft end support portion and the other roller shaft end support portion, and can be moved in the contact / separation direction with respect to the fixing roller. And an urging means for urging and urging the endless belt unit in the direction in which the endless belt is in pressure contact with the fixing roller.

  In addition, an image fixing apparatus according to the above-mentioned Japanese Patent Application Laid-Open No. 8-262903 includes a rotatable heating and fixing roll whose surface is elastically deformed, an endless belt that can run while being in contact with the heating and fixing roll, and an inner side of the endless belt. The endless belt is pressed against the heat-fixing roll, and a belt nip is provided between the endless belt and the heat-fixing roll, and a surface of the heat-fixing roll. And a pressure pad for elastically deforming.

  However, the conventional technique has the following problems. That is, in the case of the image fixing device disclosed in the above Japanese Patent Laid-Open Nos. 3-65976 and 8-262903, etc., the endless belt is configured to be pressed against the surface of the heat-fixing roll with a pressure pad. However, a part of the nip where the endless belt is pressed against the surface of the heat fixing roll is pressed against the heat fixing roll only by the tension of the endless belt. It is enough. Therefore, in the image fixing apparatus, when the recording medium carrying the toner image is heated and pressurized, the recording is performed in an area where the pressure contact force of the endless belt is insufficient due to water vapor or thermally expanded air generated from the water-containing recording medium. The medium partially floats in the nip portion of the image fixing roll, causing a problem that the toner image is scattered and the image is disturbed.

  As shown in FIG. 6, the scattering of the toner image has a V-shaped white background portion at the leading end in the sheet passing direction of the solid image, and the width of the white background portion gradually increases along the sheet passing direction. In an image that becomes narrower, water vapor or thermally expanded air generated from the recording medium concentrates along the V-shaped white background portion, so that it is remarkably generated as shown in FIG.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to generate water vapor and thermal expansion generated from a water-containing recording medium in a belt nip type image fixing apparatus. An object of the present invention is to provide an image fixing apparatus capable of preventing image disturbance caused by scattering of a toner image due to the air.

In order to solve the above-mentioned problem, the invention described in claim 1 is a nip portion that sandwiches and conveys a rotating body and a sheet member that is in contact with the rotating body and carries an unfixed image or an undried image. Forming an endless belt, a plurality of pressure members disposed inside the endless belt and pressing the endless belt against the surface of the rotating body, and heating one or both of the rotating body and the endless belt In an image fixing device provided with a heating means,
While providing an elastic layer on the back side of the endless belt,
In the gap generated between the plurality of pressure members that press the endless belt against the surface of the rotating body, the endless belt is reduced in thickness by pressing the endless belt against the surface of the rotating body with the plurality of pressure members. An image fixing device in which an elastic layer is deformed so as to be equal to or greater than a thickness of a belt in a loaded state.

  According to a second aspect of the present invention, in the image fixing apparatus according to the first aspect, the plurality of pressure members arranged on the inner side of the endless belt are a rotating body, a fixed sliding member, or both. An image fixing device comprising a combination of the above.

  Furthermore, the invention described in claim 3 is the image fixing apparatus according to claim 1 or 2, wherein a heating source is disposed inside the rotating body, and the rotating body is an unfixed image or an undried image. An image fixing device configured to be in contact with an image.

  According to a fourth aspect of the present invention, in the image fixing apparatus according to any one of the first to third aspects, the endless belt comprises a belt having at least one elastic layer, and the endless belt. Any of the one or more elastic layers constituting the endless belt is set to have the largest ratio to the total thickness of the endless belt, and a release layer is provided on the outermost layer of the endless belt, so that the total thickness of the endless belt is In the image fixing device, a reinforcing layer having a tensile strength higher than that of the elastic layer is disposed on the surface side of the elastic layer having the largest thickness ratio.

  Furthermore, the invention described in claim 5 is the image fixing apparatus according to claim 4, wherein the release layer is made of a resin containing a fluorine element.

  The invention described in claim 6 is the image fixing device according to claim 4, wherein the reinforcing layer is made of polyimide resin.

  Furthermore, the invention described in claim 7 is the image fixing apparatus according to claim 4, wherein the reinforcing layer is made of metal.

  According to the present invention, the elastic layer is provided on the back surface side of the endless belt, and in the gap generated between the plurality of pressure members that press the endless belt against the surface of the rotating body, the endless belt is attached by the plurality of pressure members. Since the elastic layer is deformed so that the thickness of the endless belt becomes equal to or greater than the thickness of the unloaded belt by pressing against the surface of the rotating body, the endless belt can be moved between a plurality of pressure members. Internal stress generated by the deformed elastic layer of the belt acts to press the endless belt against the rotating body. Therefore, the adhesion between the endless belt and the rotating body between the plurality of pressure members can be improved, and the endless belt may be separated from the rotating body by water vapor or thermally expanded air generated from the water-containing recording medium. In addition, it is possible to prevent image disturbance due to scattering of the toner image.

  According to the present invention, in the image fixing apparatus of the belt nip type, the image fixing apparatus capable of preventing the occurrence of image disturbance due to the scattering of the toner image due to the water vapor or the thermally expanded air generated from the water-containing recording medium. Can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1 is a cross-sectional configuration diagram showing an image fixing apparatus according to a first embodiment of the present invention.

  In FIG. 1, reference numeral 111 denotes a fixing roll as a rotating body. The fixing roll 111 is formed by coating an aluminum cored bar 112 with an elastic layer 113 made of silicone rubber having a thickness of 1.5 mm. Further, a roll having an outer diameter of 65 mm is used in which the surface of the elastic layer 113 is coated with a tube 114 made of PFA resin having a thickness of 30 μm as a release layer.

  In addition, a halogen lamp 115 is inserted as a heating source inside the fixing roll 111, and the surface temperature of the fixing roll 111 is detected by a temperature sensor (not shown) and controlled by a temperature controller. The surface is controlled to a predetermined temperature.

  An endless belt 121 is wound around the surface of the fixing roll 111. The endless belt 121 is stretched by three tension rolls 122 to 124 arranged inside the endless belt 121, and by a tension roll 122 as a plurality of pressure members and a fixed sliding member 125. The fixing nip 131 is formed by being pressed against the surface of the fixing roll 111 which is a rotating body.

  As shown in FIG. 1, the fixed sliding member 125 includes a pressure plate 126 made of stainless steel and a support plate 128 on which an elastic layer 127 such as silicone rubber fixed on the pressure plate 126 is laminated. It is composed of

  In the present embodiment, the belt pressing member is described using a combination of the rotating body 122 and the fixed sliding member 125, but the present invention is not limited to these combinations, and the rotating body A combination of each other or fixed sliding members may be used. In this embodiment, the member that contacts the unfixed toner image or the undried ink image is described as a rotating body. However, even if the member that contacts the unfixed toner image or the undried ink image is an endless belt. Good.

  By the way, the image fixing apparatus according to this embodiment includes an endless belt that forms a nip portion that heats and fixes a rotating body and a sheet member that is in contact with the rotating body and carries an unfixed image or an undried image. And a plurality of pressure members that are arranged inside the endless belt and press the endless belt against the surface of the rotating body, and heating means that heats one or both of the rotating body and the endless belt. In the image fixing apparatus, an elastic layer is provided on the back side of the endless belt, and an endless belt is formed by a plurality of pressure members in a gap generated between the pressure members that press the endless belt against the surface of the rotating body. Is pressed against the surface of the rotating body so that the thickness of the endless belt is equal to or greater than the thickness of the unloaded belt. It is configured to deform the elastic layer.

  In this embodiment, the endless belt is composed of a belt having at least one elastic layer, and one of the one or more elastic layers constituting the endless belt has the highest ratio to the total thickness of the endless belt. The release layer is provided on the outermost surface layer of the endless belt, and the tensile strength is higher than that of the elastic layer on the surface side of the elastic layer having the largest thickness ratio to the total thickness of the endless belt. A large reinforcing layer is arranged.

  That is, as shown in FIG. 2, the endless belt 121 is composed of an endless belt having an elastic layer 121c made of at least one layer of silicone rubber or the like, and the elastic layer 121c constituting the endless belt 121 is composed of the endless belt 121. The ratio with respect to the total thickness is set to be the largest. Further, a release layer 121 a made of a copolymer resin of tetrafluoroethylene and perfluoroalkoxyethylene (hereinafter abbreviated as “PFA resin”) or the like is provided on the outermost layer of the endless belt 121. In addition, a reinforcing layer 121b made of a polyimide resin having a tensile strength higher than that of the elastic layer 121c is arranged on the surface side of the elastic layer 121c having the largest thickness ratio to the total thickness of the endless belt 121. Further, a release layer 121 d made of PFA resin or the like is provided on the back side of the endless belt 121.

  Further, in this embodiment, as shown in FIG. 3, in the gap 130 formed between the tension roll 122 that presses the endless belt 121 against the surface of the fixing roll 111 and the fixed sliding member 125, these tension rolls When the endless belt 121 is pressed against the surface of the fixing roll 111 by 122 and the fixed sliding member 125, the elastic layer 121c is deformed so that the thickness of the endless belt 121 is equal to or greater than the thickness of the belt 121 in the no-load state. It is configured to let you.

  In this embodiment, as the fixed sliding member 125 that presses the endless belt 121 against the fixing roll 111, a pressure plate 126 made of stainless steel or the like, and an elastic layer such as silicone rubber fixed on the pressure plate 126. Since the one constituted by the support plate 128 on which 127 is laminated is used, a release layer 121d made of PFA resin is formed on the inner surface of the endless belt 121 in order to reduce sliding resistance.

  Further, in this embodiment, since the fixed sliding member 125 is used as one member of the belt pressure member, the low sliding resistance layer 121d made of the PFA resin layer is provided on the belt inner surface. When all are rotating bodies, the low sliding resistance layer 121d is not necessarily required. The outermost release layer 121a is not limited to the PFA resin, and is not particularly limited as long as it has a good release property.

  In the present embodiment, only one elastic layer 121c is provided. However, the elastic layer may be a plurality of layers. For example, an elastic layer may be provided between the release layer 121a and the reinforcing layer 121b. Good. However, in this case, the thickness of the elastic layer provided on the front surface side of the reinforcing layer 121b is desirably thinner than the elastic layer 121c provided on the back surface side of the reinforcing layer 121b.

  The endless belt 121 used in the image fixing apparatus according to the above embodiment is repeatedly subjected to bending stress by being driven to rotate. At this time, when the thickness of the endless belt 121 is increased and the separation layer 121a made of PFA resin is formed on the surface of the elastic layer 121c, the elastic layer 121c is formed according to the thickness and curvature of the endless belt 121. Since the surface side expands and contracts, the separation layer 121a made of the PFA resin on the outermost surface is also subjected to expansion and contraction stress. Further, a torsional stress is generated due to a difference in the belt moving speed in the axial direction of the fixing roll 111. Also in this case, since the tensile strength of the elastic layer 121c is weak and easily deformed, torsion occurs, which reaches the release layer 121a on the surface.

  In general, a fluororesin having good releasability is weak in tensile strength, and therefore, when deformed together with the elastic layer, it easily deforms to the plastic region, and the endless belt 121 is likely to be wrinkled to cause image defects.

  In the present embodiment, as shown in FIG. 2, since the reinforcing layer 121b having a higher tensile strength than the elastic layer 121c exists in the vicinity of the surface layer of the endless belt 121, the amount of expansion and contraction of the belt surface can be minimized. Wrinkling of the release layer 121a can also be prevented. For this reason, the material of the reinforcing layer 121b is preferably a material having a higher tensile strength than the elastic layer 121c, and is not particularly limited as long as it has a heat resistance that can withstand the fixing temperature. A metal material such as stainless steel or nickel can be used. Further, the reinforcing layer 121b has a surface side more than the center in the thickness direction of the elastic layer 121c having the largest thickness ratio with respect to the total thickness of the endless belt 121 in order to minimize deformation of the surface release layer 121a. In addition, it is desirable to arrange it at a position closer to the vicinity of the surface.

  FIG. 3 is a schematic diagram for explaining belt deformation at the time of pressing by the pressure member to the fixing roll of the endless belt, which is a feature of the present invention.

  As shown in FIG. 2, the endless belt 121 has an elastic layer 121 c, and the elastic layer 121 c is incompressible, so that the tension roll 122 and the fixed sliding member 125 press the fixing roll 111. The elastic layer 121c pushed out by is pushed out to the portion of the gap 130 that is not in contact with the tension roll 122 and the fixed sliding member 125 on the inner surface of the belt opposite to the fixing roll 111 side where deformation is restricted. For this reason, the belt thickness of the tension roll 122 and the fixed sliding member 125 becomes thicker than the belt thickness at the time of non-pressurization due to the extruded elastic layer 121c, and the strength is increased. Further, due to the internal stress of the extruded elastic body 121c, a force F that presses the endless belt 121 against the fixing roll 111 is also generated in a portion where the tension roll 122 and the fixed sliding member 125 are not in contact with each other. Therefore, it is possible to prevent the recording medium P as a sheet-like member from being peeled off from the fixing roll 111 by water vapor or air heated in the fixing nip portion 131.

  At this time, depending on the distance between the tension roll 122 and the fixed sliding member 125 and the elastic modulus and thickness of the elastic layer 121c of the endless belt 121, as shown in FIG. A portion where the elastic layer 121c is not pushed out by pressing with 125 is formed. In this case, the force for pressing the recording medium P against the fixing roll 111 becomes insufficient, and image defects such as toner scattering occur. Therefore, it is desirable that the endless belt 121 is deformed in the entire region between the tension roll 122 and the fixed sliding member 125.

  In FIG. 1, reference numeral 140 denotes a peeling member for the recording medium P, 141 denotes a guide member for guiding the recording medium P, and 142 denotes an exit roll of the image fixing device.

  In the image fixing apparatus according to this embodiment having the above configuration, the toner image is scattered by the water vapor or the thermally expanded air generated from the water-containing recording medium in the belt nip type image fixing apparatus as follows. It is possible to prevent image disturbance due to the like.

  That is, in the image fixing apparatus according to this embodiment, as shown in FIG. 1, the recording medium P carrying the unfixed toner image T is conveyed to the fixing nip 131 by the endless belt 121, and the recording medium P Is fixed on the recording medium P while the toner passes through the fixing nip portion 131.

  At this time, the endless belt 121 is pressed against the surface of the fixing roll 111 by the fixed sliding member 125 on the inlet side of the fixing nip portion 131, and the recording medium P passing through the fixing nip portion 131 passes through the fixing roll 111. The fixing roll 111 and the endless belt 121 are pressed while being heated by heat conduction from the fixing roll 111. Further, when the recording medium P moves to the exit side of the fixing nip portion 131, the endless belt 121 is pressed against the surface of the fixing roll 111 by the stretching roll 122 and passes through the exit portion of the fixing nip portion 131. The recording medium P is fixed by being pressed by the fixing roll 111 and the endless belt 121 while being heated by heat conduction from the fixing roll 111.

  By the way, in the fixing nip portion 131, a gap 130 inevitably exists between the fixed sliding member 125 and the stretching roll 122, and in the gap 130, the endless belt 121 is directly on the surface of the fixing roll 111. There is no member to press.

  However, in the gap 130 formed between the tension roll 122 that presses the endless belt 121 against the surface of the fixing roll 111 and the fixed sliding member 125, as shown in FIG. When the endless belt 121 is pressed against the surface of the fixing roll 111 by the member 125, the elastic layer 121c is deformed so that the thickness of the endless belt 121 is equal to or greater than the thickness of the belt 121 in an unloaded state. Yes. In FIG. 5, the elastic layer 127 of the fixed sliding member 125 is drawn away from the endless belt 121 for convenience, but the elastic layer 127 is of course in pressure contact with the endless belt 121. .

  As shown in FIG. 2, the endless belt 121 has an elastic layer 121c. The elastic layer 121c is made of silicone rubber or the like and is non-compressible. Therefore, the endless belt 121 is fixed by the tension roll 122 and the fixed sliding member 125. The elastic layer 121c pushed out by pressing the roll 111 is a portion of the gap 130 on the inner surface of the belt opposite to the fixing roll 111 side where deformation is restricted, and not in contact with the tension roll 122 and the fixed sliding member 125. Extruded. For this reason, the belt thickness of the tension roll 122 and the fixed sliding member 125 becomes thicker than the belt thickness at the time of non-pressurization due to the extruded elastic layer 121c, and the strength is increased. Further, due to the internal stress of the extruded elastic body 121c, a force F that presses the endless belt 121 against the fixing roll 111 is also generated in a portion where the tension roll 122 and the fixed sliding member 125 are not in contact with each other. For this reason, it is possible to prevent the recording medium P from being peeled off from the fixing roll 111 by water vapor or air heated in the fixing nip portion 131, and by water vapor generated from the water-containing recording medium P or thermally expanded air, It is possible to prevent image disturbance due to toner image scattering.

Example 1
In this embodiment, as shown in FIG. 1, the image fixing apparatus according to the above-described embodiment is embodied. As the fixing roll 111, a roller having an outer diameter of 65 mm in which a silicone rubber 113 having a thickness of 1.5 mm and a PFA resin 114 having a thickness of 30 μm are coated on an aluminum core metal 112 is used. A halogen lamp heater 115 is disposed inside the fixing roll 111, and the surface temperature of the fixing roll 111 is monitored by a temperature sensor (not shown) and controlled to a predetermined temperature. The endless belt 121 has a 60 mm inner diameter belt in which 30 μm of PFA resin 121a is formed on the surface of a 75 μm thick polyimide resin layer 121b, and a 1 mm thick silicone rubber layer 121c on the surface of a 30 μm thick PFA resin layer 121d. Two formed belts having an outer diameter of 59 mm were prepared. A thin two-component thermosetting silicone rubber was applied to a belt surface having an outer diameter of 59 mm, and then a belt having an inner diameter of 60 mm was coated thereon, and the protruding silicone rubber was removed. As a result, as the endless belt 121, a PFA resin 121a, a polyimide resin layer 121b, a silicone rubber layer 121c, and a PFA resin layer 121d are laminated from the surface side.

  The endless belt 121 was stretched with a tension of 10 kg by three tension rolls 122 to 124, that is, a lead roll 124, a pressure roll 122 and a tension roll 123. The diameters of the rolls 124, 122, and 123 were 20 mm, 23 mm, and 20 mm, and stainless steel cores coated with a PFA resin tube as a heat insulating layer were used. The endless belt 121 is pressed against the fixing roll 111 by a pressure roll 122 and a fixed sliding member 125. As the fixed sliding member 125, a silicone rubber member 127 having a curvature along the shape of the fixing roll 111 is disposed on a metal holder 126, and the surface thereof is covered with an embossed polyimide sheet (not shown). .

  The present inventors conducted an experiment using the image fixing apparatus configured as described above to change the fixing temperature and confirm the occurrence of image defects.

In the experiment, as shown in FIG. 6, cyan, magenta, yellow, and black on a double-side coated paper having a basis weight of 84 g / m ² using a machine modified from Fuji Xerox Co., Ltd. A sample on which an unfixed toner image T on which the four colors were superimposed was formed was prepared. The unfixed image was fixed at a process speed of 250 mm / s by changing the temperature of the fixing roll from 150 ° C. to 190 ° C. every 10 ° C., and the presence or absence of image defects as shown in FIG. 7 was confirmed.

  As a comparative example, a similar experiment was performed using an endless belt having a belt having an inner diameter of 60 mm in which a PFA resin having a thickness of 30 μm was formed on the surface of a polyimide resin layer having a thickness of 75 μm.

  Table 1 is a chart showing the results of the experiment. In Example 1, as shown in Table 1, the image defect generation temperature was improved by 30 ° C. relative to the comparative example. At this time, in Example 1, generation of wrinkles was not observed in the release layer 121a on the belt surface.

Example 2
Example 2 is a specific example of the image fixing apparatus according to Embodiment 1 described above.
FIG. 8 is a cross-sectional configuration diagram showing an image fixing apparatus according to Embodiment 2 of the present invention. In this embodiment, the endless belt is configured as a fixing belt 231 that contacts an unfixed image. The fixing belt 221 includes a belt having an inner diameter of 160 mm in which a PFA resin layer having a thickness of 30 μm is formed on the surface of a polyimide resin layer having a thickness of 75 μm, and a silicone rubber layer having a thickness of 1 mm on the surface of the PFA resin layer having a thickness of 30 μm. Two belts having an outer diameter of 159 mm were prepared. A thin two-component thermosetting silicone rubber was applied to the belt surface having an outer diameter of 159 mm, and then the belt having an inner diameter of 160 mm was coated thereon, and the protruding silicone rubber was removed. . The fixing belt 221 is in contact with the heating roll 211 to form a fixing nip portion. A heating roll 211 having an outer diameter of 65 mm in which a PFA resin 213 having a thickness of 30 μm is formed on an aluminum cored bar 212 is used. A halogen lamp heater 214 was disposed inside the heating roll 211, and the temperature was monitored by a temperature sensor (not shown) to control the temperature at 140 ° C. The fixing belt 221 was stretched at a tension of 10 kg by three tension rolls from the inside, that is, a lead roll 222, a pressure roll 223, a tension roll 224, and an outer belt heating roll 225. The outer diameter of each roll is 20 mm, 23 mm, 20 mm, and 50 mm. Three rolls on the inner side of the belt are stainless steel cores, and the outer heating roll 225 is a PFA resin tube on an aluminum core. The coated one was used. A halogen lamp heater 226 is disposed inside the heating roll 225. The fixing belt 221 is pressed against the heating roll 211 by a pressure roll 223 and a fixed sliding member 227. As the fixed sliding member 227, a silicone rubber member 229 having a curvature along the shape of the heating roll 211 was placed on a metal holder 228, and the surface thereof was covered with an embossed polyimide sheet (not shown). .

  The present inventors conducted an experiment using the image fixing apparatus configured as described above to change the fixing temperature and confirm the occurrence of image defects.

In the same manner as in Example 1 in the experiment, cyan shown in Fig. 5 on both sides coated paper having a basis weight of 84 g / m ² by Fuji Xerox Co., Ltd. MFP DocuCentreColor500cp was modified to unfixed image can be taken mechanically, magenta, A sample on which an unfixed toner image T in which four colors of yellow and black were superimposed was prepared. The unfixed image was sequentially fixed at a process speed of 250 mm / s by changing the temperature of the heating roll 211 from 150 ° C. to 190 ° C. every 10 ° C., and the presence or absence of image defects shown in FIG. 6 was confirmed.

  As a comparative example, a similar experiment was performed using an endless belt 221 having a belt having an inner diameter of 160 mm and a surface of a polyimide resin layer having a thickness of 75 μm coated with PFA resin to a thickness of 30 μm.

  Table 2 is a chart showing the results of the experiment. In Example 2, as shown in Table 2, the image defect generation temperature could be improved by 30 ° C. relative to the comparative example. At this time, in Example 2, wrinkles were not observed in the surface release layer of the endless belt 221.

  As described above, the image fixing apparatus according to the present invention includes an endless belt that forms a nip portion that heats and fixes a rotating member and a sheet member that is in contact with the rotating member and carries an unfixed image or an undried image. And a plurality of pressure members that are arranged inside the endless belt and press the endless belt against the surface of the rotating body, and heating means that heats one or both of the rotating body and the endless belt. In the image fixing apparatus, an elastic layer is provided on the back side of the endless belt, and an endless belt is formed by a plurality of pressure members in a gap generated between the pressure members that press the endless belt against the surface of the rotating body. Is pressed against the surface of the rotating body so that the thickness of the endless belt is equal to or greater than the thickness of the unloaded belt. It is obtained by configured to deform the elastic layer.

  For this reason, in the entire region where the endless belt does not contact the pressure member in the rotation direction of the endless belt between the pressure members arranged on the inner side of the endless belt, the belt in which the deformation in the belt thickness direction is unloaded toward the inner side of the belt Since the deformation of the belt exceeds the thickness of the belt, the mechanical strength of the belt between the pressure members increases, and the belt internal stress due to the deformation acts to press the belt against the rotating body. Adhesion with the rotating body can be improved, the recording medium can be prevented from floating from the fixing member, and image defects due to floating can be prevented.

FIG. 1 is a cross-sectional configuration diagram showing Embodiment 1 of an image fixing apparatus to which the present invention is applied. FIG. 2 is a cross-sectional configuration diagram showing an endless belt of an image fixing apparatus to which the present invention is applied. FIG. 3 is a first schematic diagram for explaining belt deformation when the endless belt is pressed against the rotating body by the pressure member of the image fixing apparatus to which the present invention is applied. FIG. 4 is a second schematic diagram for explaining the belt deformation when the endless belt is pressed against the rotating body by the pressure member of the image fixing apparatus to which the present invention is applied. FIG. 5 is a schematic view for explaining belt deformation when the endless belt is pressed against the rotating body by the pressure member of the image fixing apparatus to which the present invention is applied. FIG. 6 is an explanatory diagram of an image in which an image defect of a fixed image is likely to occur. FIG. 7 is an explanatory diagram of an example of occurrence of an image defect in a fixed image. FIG. 8 is a cross-sectional configuration diagram showing Embodiment 2 of the image fixing apparatus to which the present invention is applied.

Explanation of symbols

  111: fixing roll (rotating body), 112: aluminum core, 113: elastic layer, 114: PFA tube, 115: halogen lamp, 121: endless belt, 121a: release layer, 121b: reinforcing layer, 121c: Elastic layer, 121d: release layer, 122: pressure roll (pressure member), 123-124: tension roll, 125: fixed sliding member (pressure member).

Claims (7)

A rotating member, an endless belt that forms a nip portion that heats and fixes a sheet member that is in contact with the rotating member and carries an unfixed image or an undried image, and is disposed inside the endless belt. In an image fixing apparatus comprising: a plurality of pressure members that press the belt against the surface of the rotating body; and a heating unit that heats one or both of the rotating body and the endless belt.
While providing an elastic layer on the back side of the endless belt,
In the gap formed between a plurality of pressure members that press the endless belt against the surface of the rotating body, the endless belt is reduced in thickness by pressing the endless belt against the surface of the rotating body with the plurality of pressure members. An image fixing apparatus, wherein an elastic layer is deformed so as to be equal to or greater than a thickness of a belt in a loaded state. 2. The image fixing apparatus according to claim 1, wherein a plurality of pressure members arranged inside the endless belt are made of a rotating body, a fixed sliding member, or a combination of both. 3. The image fixing device according to claim 1, wherein a heating source is disposed inside the rotating body, and the rotating body is configured to contact an unfixed image or an undried image. An image fixing device. 4. The image fixing device according to claim 1, wherein the endless belt includes a belt having at least one elastic layer, and one of the one or more elastic layers constituting the endless belt includes: The ratio of the endless belt to the total thickness is set to be the largest, and a release layer is provided on the outermost layer of the endless belt, and the elastic layer has the largest thickness ratio to the total thickness of the endless belt. An image fixing apparatus comprising a reinforcing layer having a tensile strength higher than that of the elastic layer. 5. The image fixing device according to claim 4, wherein the release layer is made of a resin containing a fluorine element. 5. The image fixing device according to claim 4, wherein the reinforcing layer is made of polyimide resin. 5. The image fixing device according to claim 4, wherein the reinforcing layer is made of metal.

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