JP2005227612A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device in which recording paper is steadily conveyed by realizing a structure which prevents slide friction between a pressure application member and an endless belt which form a wide nip between them. <P>SOLUTION: The fixing device includes: a heat roll 611; a pressing belt member 63 in which a pressing belt 612 is stretched tight by tension rolls 613, 614, and 615; a fixing belt 610 stretched tight between the heat roll 611 and the pressing belt member 63; and a pressure roll 62 which forms the nip N between the fixing belt 610 and the pressure roller 62 itself by abutting on the peripheral face of the fixing belt 610 in the area where the fixing belt 610 is wrapped in the pressing belt member 63. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fixing device and the like, and more particularly to a fixing device used in an image forming apparatus using an electrophotographic system.

  In an image forming apparatus such as a copying machine or a printer using an electrophotographic method, for example, a photosensitive member formed in a drum shape is uniformly charged, and the photosensitive member is exposed to light controlled based on image information. An electrostatic latent image is formed on the photoreceptor. The electrostatic latent image is converted into a visible image (toner image) with toner, and the toner image is further transferred onto a recording sheet and fixed by a fixing device to form an image.

  In a fixing device used in such an image forming apparatus, as shown in FIG. 6, a heating source 113 is provided inside a cylindrical metal core 111, and a release layer 112 is formed on the outer peripheral surface of the metal core 111. The fixing roll 110 and the fixing roll 110 are pressed against each other, and a heat-resistant elastic layer 122 and a release layer 123 made of a heat-resistant resin film or a heat-resistant rubber film are formed on the outer peripheral surface of the core metal 121. It is comprised with the pressure roll 120. Then, the recording paper carrying the unfixed toner image is passed between the fixing roll 110 and the pressure roll 120, and the unfixed toner image is heated and pressed to thereby apply the toner to the recording paper. The image is fixed. Such a fixing device is called a heating roll method and is generally widely used.

By the way, when it is intended to increase the speed of the heating roll type fixing device, it is necessary to widen the nip width in proportion to the fixing speed in order to supply a sufficient amount of heat to the toner and the recording paper. As a method of widening the nip width, there are a method of increasing the load between the fixing roll and the pressure roll, a method of increasing the thickness of the elastic body, and a method of increasing the roll diameter.
However, in the method of increasing the load and the method of increasing the thickness of the elastic body, the uneven nip width and paper wrinkle occur because the shape of the nip width due to the deflection of the roll becomes non-uniform along the roll axis. This causes image quality problems such as In addition, the method of increasing the roll diameter causes problems that the apparatus is increased in size and the time (warm-up time) until the roll is raised from room temperature to a fixable temperature is increased.

  Therefore, in order to solve these problems and realize a fixing device corresponding to the speedup of the image forming apparatus, the applicant of the present invention has a tension roll formed by a fixing roll whose surface is covered with an elastic body and a plurality of support rolls. And a fixing device including a pressure applying member having a pressure contact surface that presses the endless belt along the surface of the fixing roll so as to form a nip region between the endless belt and the fixing roll. A technique has been proposed (see, for example, Patent Document 1).

  Furthermore, the present applicant has a rotatable fixing roll whose surface is elastically deformed, an endless belt that can run while being in contact with the fixing roll, and a pressure pad that is arranged in a non-rotating state inside the endless belt. The endless belt is pressed against the fixing roll so that a contact surface with the fixing roll is formed by the pressure pad, and a belt nip is provided between the endless belt and the fixing roll to pass the sheet. A technique related to a fixing device configured to locally elastically deform the exit side of the sheet on the surface has been proposed (see, for example, Patent Document 2).

  In the techniques described in Patent Document 1 and Patent Document 2, an endless belt is pressed against a fixing roll by a pressure applying member to form a belt nip. By adopting such a configuration, the width of the belt nip formed by the fixing roll and the endless belt can be easily made larger than the width of the conventional roll nip between the fixing roll and the pressure roll. The speed of the forming apparatus can be increased, and the apparatus can be easily downsized.

Japanese Patent Laid-Open No. 9-34291 (pages 5-7) Japanese Patent No. 3298354 (pages 4-7)

  By the way, in the fixing devices described in Patent Document 1 and Patent Document 2 (collectively referred to as “belt nip method”), a wide nip is formed and a uniform and high nip pressure is applied to the nip portion. However, since a configuration in which the endless belt is pressed against the fixing roll by a pressure applying member (pressure pad) is adopted, sliding friction is generated between the pressure applying member and the endless belt. Therefore, a lubricant is applied between the pressure applying member and the endless belt, or a low friction member is disposed on the pressure applying member, and a lubricant is applied to the friction surface between the low friction member and the endless belt. By applying it, the sliding property of both is improved.

However, in order to maintain good slipperiness when the endless belt slides on the pressure applying member that applies a uniform and high nip pressure in the nip portion, a lubricant is applied to the inner peripheral surface of the endless belt for a long period of time. It is necessary to supply it stably. Further, since the pressure is applied between the pressure applying member and the endless belt, the applied lubricant is slid in the sliding portion between the pressure applying member and the endless belt as the endless belt moves. Since the force pushed out from the moving part acts, it is necessary to stably hold the lubricant in the sliding part corresponding to the pushing force. Furthermore, it is necessary to prevent the sliding property between the low friction member and the endless belt from being deteriorated due to wear of the sliding surface of the low friction member with the endless belt due to the decrease in the amount of the lubricant.
As described above, the belt nip type fixing device requires a configuration for forming a uniform and high nip pressure and maintaining good slipperiness between the pressure applying member and the endless belt. If the contact resistance (sliding resistance) between the pressure-applying member and the endless belt increases, there is a possibility that the recording paper will be poorly conveyed and image defects such as paper wrinkles and image misalignment may occur. It was.

  Accordingly, the present invention has been made to solve the above technical problems, and an object of the present invention is to provide a sliding device between a pressure applying member that forms a wide nip and an endless belt in a fixing device. An object of the present invention is to realize a configuration that suppresses dynamic friction and to stably convey recording paper.

For this purpose, the fixing device of the present invention includes a heating roll, a pressing belt member in which the pressing belt is stretched between a plurality of stretching rolls, and a fixing belt that is stretched between the heating roll and the pressing belt member. The pressure belt member includes a pressure member that abuts on the outer peripheral surface of the fixing belt in a region where the fixing belt is wound and forms a nip portion with the fixing belt.
Here, the pressing belt member can employ a configuration in which the pressing belt has an elastic layer and a surface layer having a higher tensile strength than the elastic layer. The pressing belt member may be characterized in that the fixing belt is disposed so as to cover a part of the pressing member.
In addition, the pressing belt member and the pressing member can be pressed with a pressing force on the downstream side higher than the upstream side in the moving direction of the fixing belt. Further, the pressing belt member can be configured such that one of the plurality of stretching rolls is positioned downstream of the contact portion between the fixing belt and the pressure member in the fixing belt moving direction.

The fixing device of the present invention is a fixing device for fixing a toner image carried on a recording material, and is inscribed in a rotatable first belt member and a part of the outer periphery of the first belt member. It is characterized by comprising a rotatable second belt member and a pressure member that abuts on the second belt member and forms a nip portion with the second belt member.
Here, it can be set as the structure further provided with the heating member which heats a 2nd belt member or / and a pressurization member. Further, the pressurizing member may be an elastic belt that is stretched around a plurality of rolls and is configured to be rotatable, or a pressurizing roll. Further, the pressure member may be configured to include a rotatable first endless belt and a rotatable second endless belt that is inscribed in a part of the outer periphery of the first endless belt. .

  Further, the present invention is regarded as an image forming apparatus. The image forming apparatus of the present invention includes a toner image forming unit that forms a toner image, and a transfer unit that transfers a toner image formed by the toner image forming unit onto a recording material. Fixing means for fixing the toner image transferred onto the recording material to the recording material, the fixing means comprising a heating roll, a pressing belt member having a pressing belt stretched over a plurality of stretching rolls, and a heating roll A fixing belt stretched between the pressure belt member and the pressure belt member, and a pressure member that abuts on the outer peripheral surface of the fixing belt in a region where the fixing belt of the pressure belt member is wound and forms a nip portion with the fixing belt It is characterized by having.

  As an effect of the present invention, it is possible to stably convey the recording paper in the fixing device, and it is possible to form a high-quality image while suppressing the occurrence of paper wrinkles and image displacement over a long period of time.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
[Embodiment 1]
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus to which the exemplary embodiment is applied. The image forming apparatus shown in FIG. 1 is an intermediate transfer type image forming apparatus generally called a tandem type, and a plurality of image forming units 1Y, 1M, 1C, and 1K on which toner images of respective color components are formed by electrophotography. The primary transfer unit 10 that sequentially transfers (primary transfer) the color component toner images formed by the image forming units 1Y, 1M, 1C, and 1K to the intermediate transfer belt 15, and the superimposed toner image transferred onto the intermediate transfer belt 15. Are provided with a secondary transfer unit 20 that collectively transfers (secondary transfer) to a paper P that is a recording material (recording paper), and a fixing device 60 that fixes the secondary transferred image onto the paper P. Moreover, it has the control part 40 which controls operation | movement of each apparatus (each part).

  In the present embodiment, each of the image forming units 1Y, 1M, 1C, and 1K has a charger 12 that charges the photosensitive drum 11 around the photosensitive drum 11 that rotates in the direction of arrow A, and the photosensitive drum 11. A laser exposure device 13 for writing an electrostatic latent image thereon (exposure beam is indicated by a symbol Bm in the figure), each color component toner is accommodated, and the electrostatic latent image on the photosensitive drum 11 is visualized with toner. A developing unit 14, a primary transfer roll 16 that transfers each color component toner image formed on the photosensitive drum 11 to the intermediate transfer belt 15 in the primary transfer unit 10, and a drum cleaner that removes residual toner on the photosensitive drum 11. 17 and the like are sequentially arranged. These image forming units 1Y, 1M, 1C, and 1K are arranged in a substantially straight line from the upstream side of the intermediate transfer belt 15 in the order of yellow (Y), magenta (M), cyan (C), and black (K). Has been.

The intermediate transfer belt 15 as an intermediate transfer member is constituted by a film-like endless belt in which an appropriate amount of an antistatic agent such as carbon black is contained in a resin such as polyimide or polyamide. And the volume resistivity is formed so that it may become 10 < ⁶ > -10 < ¹⁴ > (omega | ohm) cm, The thickness is comprised by about 0.1 mm, for example. The intermediate transfer belt 15 is circulated and driven (rotated) at a predetermined speed in the direction B shown in FIG. 1 by various rolls. As these various rolls, a drive roll 31 that is driven by a motor (not shown) having excellent constant speed and rotates the intermediate transfer belt 15, and an intermediate that extends substantially linearly along the arrangement direction of the photosensitive drums 11. A support roll 32 that supports the transfer belt 15, a tension roll 33 that functions as a correction roll that applies a constant tension to the intermediate transfer belt 15 and prevents meandering of the intermediate transfer belt 15, and a backup provided in the secondary transfer unit 20. A cleaning backup roll 34 provided in a cleaning unit for scraping off residual toner on the roll 25 and the intermediate transfer belt 15 is provided.

The primary transfer unit 10 includes a primary transfer roll 16 that is disposed to face the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. The primary transfer roll 16 includes a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is a cylindrical bar made of metal such as iron or SUS. The sponge layer is a sponge-like cylindrical roll formed of a blend rubber of NBR, SBR, and EPDM containing a conductive agent such as carbon black and having a volume resistivity of 10 ⁷ to 10 ⁹ Ωcm. The primary transfer roll 16 is placed in pressure contact with the photosensitive drum 11 with the intermediate transfer belt 15 in between, and the primary transfer roll 16 has a voltage (with negative polarity; the same applies hereinafter) having a polarity opposite to that of the toner. (Primary transfer bias) is applied. As a result, the toner images on the respective photosensitive drums 11 are sequentially electrostatically attracted to the intermediate transfer belt 15 so as to form superimposed toner images on the intermediate transfer belt 15.

The secondary transfer unit 20 includes a secondary transfer roll 22 disposed on the toner image carrying surface side of the intermediate transfer belt 15 and a backup roll 25. The backup roll 25 is composed of a tube of EPDM and NBR blend rubber with carbon dispersed on the surface, and EPDM rubber on the inside. And it is formed so that the surface resistivity may be 10 ⁷ to 10 ¹⁰ Ω / □, and the hardness is set to 70 ° (Asker C: manufactured by Kobunshi Keiki Co., Ltd., the same applies hereinafter). The backup roll 25 is disposed on the back side of the intermediate transfer belt 15 to form a counter electrode of the secondary transfer roll 22, and a metal power supply roll 26 to which a secondary transfer bias is stably applied is disposed in contact with the backup roll 25. ing.

On the other hand, the secondary transfer roll 22 includes a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is a cylindrical bar made of metal such as iron or SUS. The sponge layer is a sponge-like cylindrical roll formed of a blend rubber of NBR, SBR, and EPDM containing a conductive agent such as carbon black and having a volume resistivity of 10 ⁷ to 10 ⁹ Ωcm. The secondary transfer roll 22 is disposed in pressure contact with the backup roll 25 with the intermediate transfer belt 15 interposed therebetween. Further, the secondary transfer roll 22 is grounded, and a secondary transfer bias is formed between the secondary transfer roll 22 and the backup roll 25. The toner image is secondarily transferred onto the paper P conveyed to the transfer unit 20.

  Further, on the downstream side of the secondary transfer portion 20 of the intermediate transfer belt 15, an intermediate transfer belt that removes residual toner and paper dust on the intermediate transfer belt 15 after the secondary transfer and cleans the surface of the intermediate transfer belt 15. A cleaner 35 is provided so as to be able to contact and separate. On the other hand, on the upstream side of the yellow image forming unit 1Y, a reference sensor (home position sensor) 42 that generates a reference signal serving as a reference for taking image forming timings in the image forming units 1Y, 1M, 1C, and 1K. It is arranged. Further, an image density sensor 43 for adjusting image quality is disposed on the downstream side of the black image forming unit 1K. The reference sensor 42 recognizes a predetermined mark provided on the back side of the intermediate transfer belt 15 and generates a reference signal. Each image forming unit is instructed by an instruction from the control unit 40 based on the recognition of the reference signal. 1Y, 1M, 1C, and 1K are configured to start image formation.

  Further, in the image forming apparatus according to the present embodiment, as a paper transport system, a paper tray 50 that stores paper P, a pickup roll 51 that picks up and transports the paper P accumulated in the paper tray 50 at a predetermined timing, and a pickup A transport roll 52 that transports the paper P fed by the roll 51, a transport chute 53 that feeds the paper P transported by the transport roll 52 to the secondary transfer unit 20, and transported after being secondarily transferred by the secondary transfer roll 22. A conveyance belt 55 that conveys the paper P to be fixed to the fixing device 60 and a fixing inlet guide 56 that guides the paper P to the fixing device 60 are provided.

  Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described. In an image forming apparatus as shown in FIG. 1, image data output from an image reading device (IIT) not shown or a personal computer (PC) not shown is subjected to predetermined image processing by an image processing device (IPS) not shown. After being applied, the image forming operation is executed by the image forming units 1Y, 1M, 1C, and 1K. In IPS, the input reflectance data is subjected to predetermined image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, moving editing, and other various image editing. Is done. The image data that has undergone image processing is converted into color material gradation data of four colors, Y, M, C, and K, and is output to the laser exposure unit 13.

  The laser exposure unit 13 irradiates the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K, for example, with an exposure beam Bm emitted from a semiconductor laser in accordance with the input color material gradation data. Yes. In each of the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K, the surface is charged by the charger 12, and then the surface is scanned and exposed by the laser exposure unit 13 to form an electrostatic latent image. The formed electrostatic latent images are developed as toner images of respective colors Y, M, C, and K by the respective image forming units 1Y, 1M, 1C, and 1K.

  The toner images formed on the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K are transferred onto the intermediate transfer belt 15 in the primary transfer unit 10 where the photosensitive drums 11 and the intermediate transfer belt 15 come into contact with each other. Transcribed. More specifically, in the primary transfer portion 10, a voltage (primary transfer bias) having a polarity opposite to the toner charging polarity (minus polarity) is applied to the base material of the intermediate transfer belt 15 by the primary transfer roll 16, and the toner image. Are sequentially superimposed on the surface of the intermediate transfer belt 15 to perform primary transfer.

  After the toner images are sequentially primary transferred onto the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves and the toner image is conveyed to the secondary transfer unit 20. When the toner image is transported to the secondary transfer unit 20, in the paper transport system, the pick-up roll 51 rotates in accordance with the timing at which the toner image is transported to the secondary transfer unit 20, and the paper of a predetermined size is transferred from the paper tray 50. P is supplied. The paper P supplied by the pickup roll 51 is transported by the transport roll 52 and reaches the secondary transfer unit 20 via the transport chute 53. Before reaching the secondary transfer unit 20, the paper P is temporarily stopped, and a registration roll (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 15 on which the toner image is carried. And the position of the toner image are aligned.

  In the secondary transfer unit 20, the secondary transfer roll 22 is pressed against the backup roll 25 via the intermediate transfer belt 15. At this time, the sheet P conveyed at the same timing is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. At this time, when a voltage (secondary transfer bias) having the same polarity as the toner charging polarity (negative polarity) is applied from the power supply roll 26, a transfer electric field is formed between the secondary transfer roll 22 and the backup roll 25. Is done. The unfixed toner image carried on the intermediate transfer belt 15 is collectively electrostatically transferred onto the paper P in the secondary transfer unit 20 pressed by the secondary transfer roll 22 and the backup roll 25. .

Thereafter, the sheet P on which the toner image has been electrostatically transferred is transported as it is while being peeled off from the intermediate transfer belt 15 by the secondary transfer roll 22, and transported downstream of the secondary transfer roll 22 in the sheet transport direction. It is conveyed to the belt 55. The conveyance belt 55 conveys the paper P to the fixing device 60 in accordance with the optimum conveyance speed in the fixing device 60. The unfixed toner image on the paper P conveyed to the fixing device 60 is fixed on the paper P by being subjected to a fixing process by heat and pressure by the fixing device 60. Then, the paper P on which the fixed image is formed is conveyed to a paper discharge placement unit provided in a discharge unit of the image forming apparatus.
On the other hand, after the transfer onto the paper P is completed, the residual toner remaining on the intermediate transfer belt 15 is conveyed to the cleaning unit as the intermediate transfer belt 15 rotates, and the cleaning backup roll 34 and the intermediate transfer belt cleaner 35 are transferred. Is removed from the intermediate transfer belt 15.

Next, the fixing device 60 used in the image forming apparatus of the present embodiment will be described.
FIG. 2 is a diagram illustrating the configuration of the fixing device 60 according to the present embodiment. The fixing device 60 includes a fixing belt module 61 and a pressure roll 62 as an example of a pressure member.
The fixing belt module 61 includes a fixing belt (second belt member) 610 that rotates in the direction of arrow A, a heating roll 611 in which a halogen heater 616 as a heat generating member is disposed, and a fixing belt 610 that is a pressure roll 62. It is comprised by the press belt member (1st belt member) 63 which presses. The fixing belt 610 is stretched around a heating roll 611 and a pressing belt member 63.

  The fixing belt 610 has a base layer made of polyimide resin having a thickness of 75 μm, an elastic intermediate layer having a thickness of 300 μm laminated on the base layer, and a release layer on the surface side (outer peripheral surface side). It is an endless belt having a multilayer structure composed of a surface layer formed of 30 μm PFA resin (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin). Here, the elastic intermediate layer is provided to improve the image quality especially for color images, and in this embodiment, a silicone rubber having a hardness of 20 ° (JIS-A) is used.

The heating roll 611 is a hard roll made of aluminum having a thickness of 5 mm and having an outer diameter of 65 mmφ and a length of 350 mm. The heating roll 611 is rotated in the direction of arrow B by a drive motor (not shown) to rotate the fixing belt 610 in the direction of arrow A at a surface speed of 220 mm / s.
A halogen heater 616 rated at 1200 W is disposed inside the heating roll 611 to heat the fixing belt 610. At that time, in the heating roll 611, based on the measured values of the temperature sensor 617 a arranged to contact the surface of the fixing belt 610 and the temperature sensor 617 b arranged to contact the surface of the heating roll 611. The control unit 40 (see FIG. 1) of the image forming apparatus controls the surface temperature of the heating roll 611 when the rotation is stopped to 190 ° C. and the surface temperature of the fixing belt 610 during the rotation operation to 170 ° C. ing.

The pressing belt member 63 is configured by a pressing belt 612 that is rotatably stretched by three stretching rolls 613, 614, and 615. The pressing belt member 63 is configured to stretch the fixing belt 610 and follow the fixing belt 610 as the fixing belt 610 rotates. Further, the pressing belt member 63 presses the fixing belt 610 from the inner side to the pressure roll 62 side to form a nip portion N.
The pressing belt 612 includes a silicone rubber layer having a hardness of 50 ° (JIS-A) and a thickness of 4 mm, and a polyimide layer having a thickness of 75 μm formed on the outer surface of the silicone rubber layer. The tension rolls 613, 614, and 615 have a stainless steel roll as a core, and an outer surface of which is coated with an elastic layer made of silicone rubber having a hardness of 30 ° (JIS-A) and a thickness of 3 mm. It is a roll of.

On the other hand, the pressure roll 62 is a roll having an outer diameter of 60 mmφ and a length of 350 mm, in which a core formed of aluminum having a thickness of 5 mm is covered with a PFA resin layer having a thickness of 30 μm. The pressure roll 62 is rotated in the direction of the arrow C at a surface speed of 220 mm / s by a drive motor (not shown), like the fixing belt 610.
The pressure roll 62 is disposed so as to be pressed from the fixing belt module 61 between the tension roll 613 and the tension roll 615 inside the pressing belt member 63 in the fixing belt module 61. The surface of the pressure roll 62 is configured to be covered (wrapped) with the fixing belt 610 and further with the pressing belt 612 at the contact portion (nip portion N) with the fixing belt module 61.

Next, a fixing operation in the fixing device 60 of the present embodiment will be described.
The sheet P on which the unfixed toner image is electrostatically transferred in the secondary transfer unit 20 (see FIG. 1) of the image forming apparatus is conveyed toward the nip N of the fixing apparatus 60 by the conveyance belt 55 and the fixing inlet guide 56. It will be. The unfixed toner image on the surface of the paper P passing through the nip portion N is fixed on the paper P by pressure (nip pressure) acting on the nip portion N and heat.
At that time, the nip pressure acting at the nip portion N is formed by the pressing belt member 63. That is, in the nip portion N, the pressing belt 612 and further the fixing belt 610 wrap around the tension roll 613 inside the pressing belt member 63 so that a part of the surface of the pressing roll 62 is wrapped evenly. The tension roll 615 is disposed so as to be parallel to the pressure roll 62, and the pressure roll 62 is disposed between the tension roll 613 and the tension roll 615.

FIG. 3 is a diagram illustrating the nip pressure in the nip portion N. As shown in FIG. 3, the tension rolls 613 and 615 are arranged in parallel to the pressure roll 62, and the pressure roll 62 enters between the tension roll 613 and the tension roll 615. By arranging in this way, in the nip portion N, a tension toward the tension roll 613 and the tension roll 615 acts on the pressing belt 612. Therefore, the tension of the pressure belt 612 generates a force toward the pressure roll 62 and constitutes a part of the nip pressure. Further, in the pressing belt 612, a silicone rubber layer having a thickness of 4 mm is deformed (bent) between the stretching roll 613 and the stretching roll 615, so that internal stress is generated in the pressing belt 612 at the nip portion N. To do. Therefore, this internal stress also generates a force toward the pressure roll 62, and constitutes a part of the nip pressure.
Further, since the tension toward the tension roll 613 and the tension roll 615 also acts on the fixing belt 610, the tension of the fixing belt 610 generates a force toward the pressure roll 62, and the nip pressure is reduced. Parts. Since the fixing belt 610 is not provided with a silicone rubber layer having a thickness similar to that of the pressing belt 612, the internal stress is extremely small and is negligible as an element constituting the nip pressure.

Thus, in the nip portion N, it is possible to form a uniform high nip pressure of 0.5 to 0.6 kgf / cm ² over the entire area of the nip portion N by the pressing belt 612 and further the fixing belt 610. . Therefore, when the sheet P is heated and conveyed through the nip portion N, “floating” between the sheet P and the fixing belt 610 caused by water vapor generated from the sheet P can be suppressed. Good adhesion can be maintained. As a result, it is possible to suppress the occurrence of partial gloss unevenness due to such “floating” and form a high-quality fixed image.
Further, the nip portion N can be set wide by the configuration in which the fixing belt 610 is wrapped around the pressure roll 62, so that stable fixing performance corresponding to high speed can be ensured.

Further, the pressing belt member 63 is configured such that the pressing belt 612 follows the fixing belt 610 as the fixing belt 610 rotates. For this reason, since the fixing belt 610 has a very small sliding resistance in the nip portion N due to its structure, the fixing belt 610 can always rotate smoothly.
By the way, for example, in the configuration in which the nip portion N is pressed by a fixed pressure applying member, a sliding resistance is generated between the fixing belt 610 and the pressure applying member. Therefore, when the paper P is transported through the nip portion N by the driving force of the pressure roll 62, the paper P is transported by the pressure roll due to the sliding resistance that the paper P receives from the pressure applying member via the fixing belt 610. In some cases, slippage may occur between the paper P and the pressure roll 62 because the rotation of 62 cannot follow. As a result, the smooth conveyance of the paper P is hindered, and there is a risk of image misalignment and paper wrinkling on the paper P.

On the other hand, in the fixing device 60 of the present embodiment, the pressing belt 612 is driven by the fixing belt 610 as the fixing belt 610 rotates, so that the sliding resistance received by the fixing belt 610 is extremely small, and the pressure roll The rotation at the same speed as 62 can be maintained. Therefore, the paper P conveyed by the pressure roll 62 does not receive sliding resistance from the fixing belt 610, and is smoothly conveyed without causing slip while always following the rotation of the pressure roll 62. Therefore, it is possible to suppress image misalignment and paper wrinkles on the paper P.
In particular, the pressure belt 612 has a polyimide layer formed on the outer surface of the silicone rubber layer on the fixing belt 610 side. Since this polyimide layer has an extremely high tensile strength compared to the silicone rubber layer and is difficult to expand and contract, it has a function of preventing the deformation of the silicone rubber layer at the nip N described above from being transmitted to the fixing belt 610. Therefore, the surface speed of the pressing belt 612 can be made constant over the entire area of the nip portion N regardless of the deformation of the silicone rubber layer. Therefore, the fixing belt 610 can prevent deformation of the silicone rubber layer at the nip portion N. It is possible to rotate at the same speed as the pressure roll 62 without being affected.

  In the fixing device 60 according to the present embodiment, the pressure belt member 63 is configured such that the pressure belt 612 is configured to be freely rotated by three tension rolls 613, 614, and 615. Any other configuration can be adopted as long as it is configured to press the rotatable pressing belt 612 with the nip portion N having a certain width or more toward the pressure roll 62 side. For example, a configuration in which the pressing belt 612 is configured to be rotatably rotated by two stretching rolls 613 and 615, or a configuration in which the pressing belt 612 is stretched by four or more stretching rolls is also used. Can do.

Subsequently, the heat acting on the nip portion N is supplied by the fixing belt 610. The fixing belt 610 is configured to be heated through a heating roll 611 from a halogen heater 616 disposed inside a heating roll 611 that is a heating member. The fixing belt 610 directly heats the paper P to fix the toner image on the paper P.
In such a configuration, the fixing belt 610 for heating the paper P has an extremely small heat capacity. In the case where the sheet P is heated by the fixing roll as in the conventional belt nip type fixing device so far, after the surface layer of the fixing roll passes through the region where the sheet P contacts the sheet P, the sheet P Although it is necessary to return the fixing roll to a predetermined fixing temperature during one rotation until returning to the contact area, since the heat capacity of the fixing roll is large, it is not possible to return to the predetermined fixing temperature in one rotation. There were cases where such a situation occurred. However, the fixing belt 610 has an extremely small heat capacity, and in addition, since the fixing belt 610 can contact the heating roll 611 that is a heating member with a wide wrap area (large winding angle), the fixing belt 610 is rotated during one rotation of the fixing belt 610. Can be returned to the required fixing temperature. Therefore, sufficient heat can be supplied to the paper P that is continuously passed.

In the nip portion N, the pressure roll 62 is disposed between the tension roll 613 and the tension roll 615 inside the pressing belt member 63. With such an arrangement, a convex curve is formed in the nip portion N from the pressure roll 62 toward the pressing belt member 63. Therefore, a down curl is formed on the paper P that has passed through the nip portion N. At the discharge port of the nip portion N, the down curl of the paper P and the tension roll 613 disposed on the downstream side of the pressing belt member 63 are formed. Depending on the curvature, the paper P can be easily peeled off from the fixing belt 610.
In particular, if the pressing belt member 63 is configured to press between the tension roll 613 and the pressure roll 62 and the pressing force on the downstream side of the nip portion N is increased, it is formed on the surface of the tension roll 613. A concave elastic deformation can be caused in the formed elastic layer. Therefore, the down curl generated on the paper P can be further increased, and thereby, the paper P can be more reliably separated from the fixing belt 610 at the discharge port of the nip portion N.

  Note that the sheet P peeled off from the fixing belt 610 at the nip portion N is on the downstream side in the rotation direction A of the fixing belt 610 of the nip portion N, and the peeling guide plates 671 and 672 disposed near the surface of the fixing belt 610. Is guided to the discharge guide 68. Then, the paper is transported and placed by a discharge roll 69 to a paper discharge mounting portion (not shown) provided in the discharge portion of the image forming apparatus.

Next, using the fixing device 60 of the present embodiment, an experiment on image quality evaluation and generation of paper wrinkles on the paper P was performed. In this experiment, the fixing device 60 was incorporated into a DocuCenter Color 500CP manufactured by Fuji Xerox Co., Ltd., and a single-side coated paper having a basis weight of 127 g / m ² was used as the paper P. After controlling the surface temperature of the fixing belt 610 to 170 ° C. and driving for 5 minutes without passing paper, the process speed was set to 220 mm / s, and a blue toner image having a margin of 20 mm on the periphery was supported. Ten sheets of paper P in the “blue solid” state were passed. As a result, no gloss unevenness due to partial “lifting” between the fixing belt 610 and the paper P occurs in any of the papers P, and no paper wrinkles occur.

As described above, in the fixing device 60 of the present embodiment, in the fixing device 60 of the present embodiment, the pressing belt 612 is rotatably stretched by the three stretching rolls 613, 614, and 615. The configured pressing belt member 63 can form the nip portion N and set a uniform high nip pressure over the entire nip portion N. Therefore, good adhesion between the fixing belt 610 and the paper P can be maintained in the nip portion N, so that a high-quality fixed image free from uneven gloss due to “floating” due to water vapor or the like from the paper P can be formed. Is possible.
Further, the pressing belt member 63 is configured such that the pressing belt 612 is driven by the fixing belt 610 as the fixing belt 610 rotates, so that the sliding resistance acting on the fixing belt 610 in the nip portion N is structural. The fixing belt 610 can always rotate smoothly. As a result, the paper P conveyed by the pressure roll 62 does not receive sliding resistance from the fixing belt 610, and is smoothly conveyed without causing slip while always following the rotation of the pressure roll 62. Therefore, it is possible to suppress image misalignment and paper wrinkles on the paper P.
Furthermore, by using the fixing belt 610 having an extremely small heat capacity, the fixing belt 610 can be returned to a necessary fixing temperature in a short time during one rotation of the fixing belt 610. Accordingly, it is possible to always maintain a predetermined fixing temperature in the nip portion N.

[Embodiment 2]
In the first embodiment, the image forming apparatus in which the fixing device 60 using the pressure roll 62 as the pressure member facing the fixing belt module 61 is mounted has been described. In the second embodiment, the fixing device is mounted on the image forming apparatus shown in FIG. 1 and uses a pressure belt module 64 stretched around a roll as a pressure member facing the fixing belt module 61. Will be described. In addition, about the structure similar to Embodiment 1, the same code | symbol is used and the detailed description is abbreviate | omitted here.

FIG. 4 is a side sectional view showing the configuration of the fixing device 70 according to the present embodiment. The fixing device 70 of the present embodiment is different except that a pressure belt module 64 in which a pressure belt 641 is stretched around three rolls 643, 644, and 645 is used as a pressure member. This is the same as the fixing device 60 of the first embodiment.
In the fixing device 70 of the present embodiment, the pressure belt module 64 includes a rotatable pressure belt 641, a driving roll 643 connected to a driving motor (not shown) and rotating in the direction of arrow E, and fixing at a nip portion N. A tension roll 644 that faces the belt module 61 and a tension roll 645 that stretches the pressure belt 641 are configured. The pressure belt 641 is stretched around a drive roll 643, a tension roll 644, and a tension roll 645, and the surface speed of the pressure belt 641 is 220 mm / s by the drive roll 643 as in the fixing belt module 61. Rotate in the direction of arrow D so that

  The pressure belt 641 has a hardness of 50 ° (JIS-A) and a 4 mm-thick silicone rubber layer as a base layer, a 75 μm-thick polyimide resin layer laminated on the base layer, and a surface side (outer peripheral surface side). And an endless belt having a multilayer structure composed of a surface layer made of PFA resin having a thickness of 30 μm. As the base layer, any known material can be used as long as it has elasticity. In addition to silicone rubber, fluorine rubber, polyolefin rubber, urethane rubber, etc. are appropriately selected according to the usage environment such as temperature. It can also be used.

As the surface layer, a material having good releasability such as PFA resin is used in order to prevent toner adhesion. In addition, the polyimide resin layer has an extremely high tensile strength compared to the silicone rubber layer as the base layer and is difficult to expand and contract. Therefore, the pressure belt is caused by deformation of the silicone rubber layer that occurs when the pressure belt 641 rotates. The surface speed non-uniformity of 641 can be suppressed. Therefore, the surface speed of the pressure belt 641 can be made constant over the entire area of the nip portion N regardless of the deformation of the silicone rubber layer. The sheet P can be conveyed at a constant speed without being affected by the deformation. Therefore, in the polyimide resin layer, a metal or the like can be used in addition to the polyimide resin as long as the material has a higher tensile strength than the base layer.
Further, the pressure belt 641 may be configured such that an elastic intermediate layer is provided between the polyimide resin layer and the surface layer. This elastic intermediate layer can improve the image quality especially for color images. For example, silicone rubber having a hardness of 20 ° (JIS-A) can be used.

  The fixing belt module 61 and the pressure belt module 64 include a tension roll 644 of the pressure belt module 64 between the tension roll 613 and the tension roll 615 inside the pressing belt member 63 in the fixing belt module 61. It is arranged so as to be pressed toward the fixing belt module 61 side. Further, the tension roll 615 of the fixing belt module 61 is disposed between the driving roll 643 and the tension roll 644 in the pressure belt module 64 so as to be pressed toward the pressure belt module 64. With such an arrangement, the fixing belt 610 and the pressure belt 641 are wrapped together at the contact portion (nip portion N) between the pressure belt module 64 and the fixing belt module 61.

As described above, in the fixing device 70 of the present embodiment, the downstream side of the nip portion N, that is, the tension roll 613 and the tension roll 615 of the fixing belt module 61 and the tension roll 644 of the pressure belt module 64 are used. In the formed region, a nip pressure is formed by pressing the pressing belt member 63 against the tension roll 644 of the pressing belt module 64. Further, in the region upstream of the nip portion N, that is, in the region formed by the tension roll 615 of the fixing belt module 61 and the drive roll 643 and the tension roll 644 of the pressure belt module 64, the tension belt 63 is stretched. A nip pressure is formed by pressing the pressure belt module 64 against the roll 615.
Therefore, in the nip portion N, a uniform high nip pressure of 0.5 to 0.6 kgf / cm ² can be set over the entire nip portion N, so that the paper P is heated and conveyed through the nip portion N. In this case, “floating” between the paper P and the fixing belt 610 due to water vapor generated from the paper P can be suppressed, and good adhesion between the fixing belt 610 and the paper P can be maintained. Accordingly, partial gloss unevenness due to such “floating” does not occur, and a high-quality fixed image can be formed.
Further, since the nip portion N can be set wide by the configuration in which the fixing belt 610 is wrapped around the pressure belt module 64, stable fixing performance corresponding to high speed can be ensured.

Further, the pressing belt member 63 of the fixing belt module 61 is configured such that the pressing belt 612 is driven by the fixing belt 610 as the fixing belt 610 rotates. Only a small sliding resistance works, and the fixing belt 610 can always rotate smoothly. Accordingly, the paper P conveyed by the pressure belt module 64 does not receive sliding resistance from the fixing belt 610, and smoothly follows the rotation of the pressure belt module 64 without causing slip. Since it is conveyed, the occurrence of image misalignment and paper wrinkles on the paper P can be suppressed.
In addition, by using the fixing belt 610 having an extremely small heat capacity, the fixing belt 610 can be returned to a necessary fixing temperature in a short time during one rotation of the fixing belt 610. Accordingly, it is possible to always maintain a predetermined fixing temperature in the nip portion N.

By the way, in the fixing device 70 of the present embodiment, the tension roll 644 of the pressure belt module 64 is positioned upstream of the tension roll 613 of the pressing belt member 63 of the fixing belt module 61 in the conveyance direction of the paper P. It is configured. With such an arrangement, a convex curve is formed on the downstream side of the nip portion N from the tension roll 644 of the pressure belt module 64 toward the pressing belt member 63 of the fixing belt module 61. Therefore, a down curl is formed on the paper P that has passed through the nip portion N. At the discharge port of the nip portion N, the down curl of the paper P and the tension roll 613 disposed on the downstream side of the pressing belt member 63 are formed. Depending on the curvature, it is possible to peel the paper P from the fixing belt 610 satisfactorily.
At that time, if it is configured to press between the tension roll 613 of the pressing belt member 63 and the tension roll 644 of the pressure belt module 64 and the pressing force on the downstream side of the nip portion N is increased, the tension is increased. Concave elastic deformation can be caused in the elastic layer formed on the surface of the roll 613. Therefore, the down curl generated on the paper P can be formed larger, and the paper P can be peeled off from the fixing belt 610 more reliably.

Next, using the fixing device 70 of the present embodiment, an experiment on image quality evaluation and generation of paper wrinkles on the paper P was performed. In this experiment, the fixing device 70 was incorporated into a DocuCenter Color 500CP manufactured by Fuji Xerox Co., Ltd., and a single-side coated paper having a basis weight of 127 g / m ² was used as the paper P. After controlling the surface temperature of the fixing belt 610 at 170 ° C. for 5 minutes, the paper was driven for 5 minutes, and then a blue toner image having a margin of 20 mm on the periphery was carried at a process speed of 220 mm / s. Ten sheets of paper P in the “blue solid” state were passed. As a result, no gloss unevenness due to partial “lifting” between the fixing belt 610 and the paper P occurs in any of the papers P, and no paper wrinkles occur.

[Embodiment 3]
In the first embodiment, the fixing device 60 uses a pressure roll 62 as a pressure member facing the fixing belt module 61. In the second embodiment, the pressure belt module 64 is used as a pressure member facing the fixing belt module 61. The image forming apparatus equipped with the fixing device 70 using the above has been described. In the third embodiment, the fixing device is a fixing device mounted on the image forming apparatus shown in FIG. 1 and uses a heating belt module in which a heated belt is stretched as a pressure member facing the fixing belt module 61. The apparatus will be described. In addition, about the structure similar to Embodiment 1, the same code | symbol is used and the detailed description is abbreviate | omitted here.

FIG. 5 is a side sectional view showing the configuration of the fixing device 80 according to the present embodiment. The fixing device 80 according to the present embodiment is different from the fixing device 80 except that the heating belt 650 uses a heating belt module 65 stretched between a heating roll 651 and a pressing belt member 66 as a pressing unit. This is the same as the fixing device 60 of the first embodiment.
In the fixing device 80 of the present embodiment, the heating belt module 65 includes a heating belt (second endless belt) 650 that rotates in the direction of arrow G, and a heating roll in which a halogen heater 656 as a heat generating member is disposed. 651 and a pressing belt member 66 that presses the heating belt 650 against the fixing belt module 61. The heating belt 650 is stretched between the heating roll 611 and the pressing belt member 63.

The heating belt 650 has a base layer made of polyimide resin having a thickness of 75 μm, an elastic intermediate layer having a thickness of 300 μm laminated on the base layer, and a release layer on the surface side (outer peripheral surface side). This is an endless belt having a multilayer structure composed of a surface layer made of 30 μm PFA resin.
A heating roll 651 as a heating member is a hard roll having an outer diameter of 65 mmφ and a length of 350 mm formed of aluminum having a thickness of 5 mm. The heating roll 651 is rotated in the direction of arrow F by a drive motor (not shown), thereby rotating the heating roll 651 in the direction of arrow G at a surface speed of 220 mm / s.
A halogen heater 656 having a rating of 600 W is disposed inside the heating roll 651 to heat the heating belt 650. At that time, in the heating roll 651, based on the measured values of the temperature sensor 617c arranged to contact the surface of the heating belt 650 and the temperature sensor 617d arranged to contact the surface of the heating roll 651, The controller 40 (see FIG. 1) of the image forming apparatus controls the surface temperature of the heating roll 651 when the rotation is stopped to 120 ° C. and the surface temperature of the heating belt 650 during the rotation operation to 100 ° C. ing.

The pressing belt member 66 is configured such that a pressing belt (first endless belt) 652 is rotatably stretched by three stretching rolls 653, 654, 655. The pressing belt member 66 stretches the heating belt 650 and presses the heating belt 650 from the inner side to the fixing belt module 61 side. Therefore, the pressing belt member 66 forms a nip portion N with the fixing belt module 61, and the pressing belt 652 is configured to follow the heating belt 650 as the heating belt 650 rotates. .
The pressing belt 652 includes a silicone rubber layer having a hardness of 50 ° (JIS-A) and a thickness of 4 mm, and a polyimide layer having a thickness of 75 μm formed on the outer surface of the silicone rubber layer.
Further, the stretching rolls 653, 654, 655 have a stainless steel roll as a core, and an outer surface of which is coated with an elastic layer made of silicone rubber having a hardness of 30 ° (JIS-A) and a thickness of 3 mm. It is a roll of.

  The fixing belt module 61 and the heating belt module 65 are arranged between the tension roll 613 and the tension roll 615 inside the pressing belt member 63 in the fixing belt module 61 and inside the pressure belt member 66 in the heating belt module 65. The tension roll 655 is disposed so as to be pressed toward the fixing belt module 61. Further, the tension roll 615 of the fixing belt module 61 is disposed between the tension roll 653 and the tension roll 655 of the heating belt module 65 so as to be pressed toward the heating belt module 65. With such an arrangement, the fixing belt 610 and the heating belt 650 are wrapped with each other at the contact portion (nip portion N) between the heating belt module 65 and the fixing belt module 61.

As described above, the fixing device 80 according to the present embodiment is also formed on the downstream side of the nip portion N, that is, the tension roll 613 and the tension roll 615 of the fixing belt module 61 and the tension roll 655 of the heating belt module 65. In the region to be applied, a nip pressure is formed by the pressing of the pressing belt member 63 against the stretching roll 655 of the heating belt module 65. Further, in the upstream side of the nip portion N, that is, in the region formed by the tension roll 615 of the fixing belt module 61 and the tension roll 653 and the tension roll 655 of the heating belt module 65, the tension belt 63 is stretched. A nip pressure is applied by pressing the heating belt module 65 against the roll 615.
Therefore, in the nip portion N, a uniform high nip pressure of 0.5 to 0.6 kgf / cm ² can be set over the entire nip portion N, so that the paper P is heated and conveyed through the nip portion N. In this case, “floating” between the paper P and the fixing belt 610 due to water vapor generated from the paper P can be suppressed, and good adhesion between the fixing belt 610 and the paper P can be maintained. Accordingly, partial gloss unevenness due to such “floating” does not occur, and a high-quality fixed image can be formed.
In addition, since the nip portion N can be set wide by the configuration in which the fixing belt 610 is wrapped around the heating belt module 65, stable fixing performance corresponding to high speed can be ensured.

Further, the pressing belt member 63 of the fixing belt module 61 is configured such that the pressing belt 612 is driven by the fixing belt 610 as the fixing belt 610 rotates, so that the fixing belt 610 is extremely small at the nip portion N. Only the sliding resistance works, and the fixing belt 610 can always rotate smoothly. As a result, the sheet P conveyed by the heating belt module 65 does not receive sliding resistance from the fixing belt 610, and is smoothly conveyed without causing slip while always following the rotation of the heating belt module 65. Therefore, it is possible to suppress image misalignment and paper wrinkles on the paper P.
In addition, by using the fixing belt 610 having an extremely small heat capacity, the fixing belt 610 can be returned to a necessary fixing temperature in a short time during one rotation of the fixing belt 610. Accordingly, it is possible to always maintain a predetermined fixing temperature in the nip portion N.

  Also in the heating belt module 65, the pressing belt member 66 of the heating belt module 65 is configured such that the pressing belt 652 is driven by the heating belt 650 as the heating belt 650 rotates. In this case, only a very small sliding resistance acts on the heating belt 650. For this reason, the heating belt 650 can be rotated smoothly by the rotation of the heating roll 651 without causing slippage, so that the paper P can be transported smoothly.

Further, the heating belt 650 of the heating belt module 65 is heated by the heat supplied from the halogen heater 656 disposed inside the heating roll 651 and is conveyed to the nip portion N to heat the paper P from the back surface. Therefore, at the nip portion N, the front side of the paper P can be heated by the fixing belt 610 of the fixing belt module 61 and the back surface of the paper P can be heated by the heating belt 650 of the heating belt module 65. For this reason, the amount of heat supplied to the nip portion N can be greatly increased, so that stable fixing is performed even for the paper P that is continuously conveyed in a short time, corresponding to the increase in the speed of the image forming apparatus. It becomes possible.
At this time, the heating belt 650 of the heating belt module 65 also has an extremely small heat capacity, similarly to the fixing belt 610 of the fixing belt module 61, and in addition, the heating belt 651 that is a heat supply member has a large lap area (large Therefore, the heating belt 650 can be returned to a necessary fixing temperature while the heating belt 650 rotates once. Therefore, sufficient heat can be supplied to the paper P that is continuously passed.

By the way, in the fixing device 80 of the present embodiment, the stretching roll 655 of the pressing belt member 66 of the heating belt module 65 is upstream of the stretching roll 613 of the pressing belt member 63 of the fixing belt module 61 in the transport direction of the paper P. It is configured to be located on the side. With such an arrangement, a convex curve is formed on the downstream side of the nip portion N from the tension roll 655 of the heating belt module 65 toward the pressing belt member 63 of the fixing belt module 61. Therefore, a down curl is formed on the paper P that has passed through the nip portion N. At the discharge port of the nip portion N, the down curl of the paper P and the tension roll 613 disposed on the downstream side of the pressing belt member 63 are formed. Depending on the curvature, it is possible to peel the paper P from the fixing belt 610 satisfactorily.
At that time, if the pressing force on the downstream side of the nip portion N is increased by pressing between the tension roll 613 of the pressing belt member 63 and the tension roll 655 of the heating belt module 65, the tension is increased. A concave elastic deformation can be caused in the elastic layer formed on the surface of the roll 613. Therefore, the down curl generated on the paper P can be formed even larger, and the paper P can be peeled off from the fixing belt 610 more reliably.

Next, using the fixing device 80 of the present embodiment, an experiment regarding image quality evaluation and generation of paper wrinkles on the paper P was performed. In this experiment, the fixing device 80 was incorporated in DocuCenter Color500CP manufactured by Fuji Xerox Co., Ltd., and a single-side coated paper having a basis weight of 127 g / m ² was used as the paper P. After controlling the surface temperature of the fixing belt 610 to 170 ° C. and the surface temperature of the heating belt 650 to 100 ° C., a non-sheet-passing drive is performed for 5 minutes, and then a margin of 20 mm is formed at the peripheral portion at a process speed of 220 mm / s. Ten sheets of paper P in the “blue solid” state carrying the provided blue toner image were passed. As a result, no gloss unevenness occurred due to partial “floating” between the fixing belt 610 and the paper P, and no paper wrinkle occurred on any of the papers P.

  As an application example of the present invention, application to an image forming apparatus such as a copying machine or a printer using an electrophotographic method, for example, application to a fixing apparatus that fixes an unfixed toner image carried on a recording paper (paper). is there. Further, there is application to an image forming apparatus such as a copying machine or a printer using an ink jet method, for example, to a fixing device that dries an undried ink image carried on a recording paper (paper).

1 is a schematic configuration diagram showing an image forming apparatus of the present invention. 2 is a diagram illustrating a configuration of a fixing device according to Embodiment 1. FIG. It is a figure explaining the nip pressure in a nip part. 6 is a diagram illustrating a configuration of a fixing device according to Embodiment 2. FIG. 6 is a diagram illustrating a configuration of a fixing device according to Embodiment 3. FIG. FIG. 10 is a side sectional view showing a configuration of a conventional fixing device.

Explanation of symbols

1Y, 1M, 1C, 1K ... image forming unit, 11 ... photosensitive drum, 12 ... charger, 13 ... laser exposure device, 14 ... developing device, 15 ... intermediate transfer belt, 16 ... primary transfer roll, 17 ... drum cleaner , 20 ... secondary transfer section, 60, 70, 80 ... fixing device, 61 ... fixing belt module, 62 ... pressure roll, 63, 66 ... pressure belt member, 64 ... pressure belt module, 65 ... heating belt module, 610: Fixing belt, 611,651 ... Heating roll, 612,652 ... Pressing belt, 616,656 ... Halogen heater, 613,614,615,644,645,653,654,655 ... Stretching roll, 641 ... Pressure Belt, 643 ... Driving roll

Claims (10)

A heating roll;
A pressing belt member in which the pressing belt is stretched between a plurality of stretching rolls;
A fixing belt stretched between the heating roll and the pressing belt member;
A fixing member, comprising: a pressing member that contacts an outer peripheral surface of the fixing belt in a region where the fixing belt of the pressing belt member is wound and forms a nip portion with the fixing belt. apparatus.   The fixing device according to claim 1, wherein the pressing belt member includes an elastic layer and a surface layer having a higher tensile strength than the elastic layer.   The fixing device according to claim 1, wherein the pressing belt member is disposed so that the fixing belt covers a part of the pressure member.   The fixing device according to claim 1, wherein the pressing belt member and the pressing member are pressed with a pressing force on the downstream side higher than the upstream side in the moving direction of the fixing belt.   The press belt member is characterized in that one of the plurality of tension rolls is located downstream of the contact portion between the fixing belt and the pressure member in the moving direction of the fixing belt. Item 4. The fixing device according to Item 1. A fixing device for fixing a toner image carried on a recording material,
A rotatable first belt member;
A rotatable second belt member inscribed in a part of the outer periphery of the first belt member;
A fixing device, comprising: a pressing member that contacts the second belt member and forms a nip portion with the second belt member.   The fixing device according to claim 6, further comprising a heating member that heats the second belt member and / or the pressure member.   The fixing device according to claim 6, wherein the pressure member is an elastic belt stretched around a plurality of rolls so as to be rotatable, or a pressure roll.   The pressurizing member includes a rotatable first endless belt and a rotatable second endless belt inscribed in a part of the outer periphery of the first endless belt. 8. The fixing device according to 7. Toner image forming means for forming a toner image;
Transfer means for transferring the toner image formed by the toner image forming means onto a recording material;
Fixing means for fixing the toner image transferred onto the recording material to the recording material,
The fixing means is
A heating roll;
A pressing belt member in which the pressing belt is stretched between a plurality of stretching rolls;
A fixing belt stretched between the heating roll and the pressing belt member;
And a pressure member that abuts on the outer peripheral surface of the fixing belt in a region where the fixing belt of the pressing belt member is wound and forms a nip portion with the fixing belt. Forming equipment.

Images