JP4231717B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present inventionElectronicIt is installed in image forming devices configured as photographic printers, facsimiles, copiers, or multifunction devices with at least two of these functions.RuFixing deviceIn particular, it relates to the heat insulating material.
[0002]
[Prior art]
In an image forming apparatus using toner for forming a visible image, a fixing device is provided for fixing a toner image onto a recording material such as transfer paper. As a fixing device, a heat fixing method, a pressure fixing method, a solvent fixing method, or the like has been conventionally known. Among them, the heat fixing method is a method widely used in the past, in which heat and pressure are applied to the toner on the recording material at the nip portion to fix the toner image on the recording material.
[0003]
In a fixing device using a fixing member that forms a nip portion, it is necessary to simultaneously satisfy the two requirements of shortening the warm-up time and preventing the rigidity of the fixing member from being lowered.
[0004]
With respect to such a point, by using a heat insulating layer having high heat insulating properties, it is possible to obtain a configuration having a small effective heat capacity, a high temperature rise, and a low heat energy consumption while being a highly rigid member. In this way, the heat insulating layer is formed on the outer periphery of the core metal and heated by radiation and heat transfer from the outside (for example, Patent Document 1); the conductive layer is disposed on the outer periphery of the heat insulating layer, and the induced current Alternatively, there are those that are heated by direct current.
[Patent Document 1]
JP 2002-40855 A
[0005]
As a member having good thermal insulation, a member containing a gas such as air having low thermal conductivity is generally considered, and foamed silicone rubber is often used in fixing devices (for example, Patent Document 2).
[Patent Document 2]
JP 2000-2056815 A
[0006]
Examples of the heat insulating material having high rigidity and small deformation include porous ceramics, porous resin (Patent Document 3), and hollow particles mixed with a binder (Patent Document 4).
[Patent Document 3]
JP 2002-40855 A
[Patent Document 4]
JP 2000-275996 A
[0007]
[Problems to be solved by the invention]
  In view of the conventional technology as described above, the present invention provides a heat insulating material having higher heat insulating properties.Equipped with a fixing deviceThe issue is to provide.
[0008]
[Means for Solving the Problems]
  The above issuesA fixing rotator having an elastic layer; a pressure rotator that presses against the fixing rotator to form a nip; and a heating unit that heats the fixing rotator. In the fixing device that clamps the paper between the body and fixes the toner to the paper, the pressure rotating body includes a heat insulating layer, and the heat insulating layer is a resin fiber layer in which the outer circumferences of the adjacent hollow fibers are in contact with each other And a binder for fixing the resin fiber layer, 1-10 kg / cm of the heat insulating layer ² The thermal conductivity when pressurized with 0.08 to 0.09 W / mK and the JIS-A rubber hardness is 60 to 90 HsCan be solved.
[0009]
  The resin fiber layer may be wound around the core of the pressure rotating body, or may be a sheet in which the hollow fiber is knitted into a cloth shape.The hollow fiber preferably has a partition when viewed in cross section..
[0010]
  Conveniently, the internal space of the hollow fiber is sealed, and the sealed space in the hollow fiber is filled with xenon, krypton, argon or carbon dioxide.
[0011]
  It is preferable that the heating means is a halogen heater provided inside the fixing rotator.
[0012]
  The fixing rotating body has a resin fiber layer in which the outer peripheries of adjacent hollow fibers are in contact with each other, and the heating means is connected to the induction coil disposed inside the resin fiber layer and the resin fiber layer. Inductive heating means including a conductive layer provided on the outer periphery is preferable.
[0013]
  It is also preferable that the heating unit is provided outside the fixing rotator, and the fixing rotator includes a resin fiber layer in which the outer circumferences of adjacent hollow fibers are in contact with each other inside the elastic layer.
[0014]
  It is also preferable that the fixing rotator is a fixing belt, and a heat insulating material is disposed on the fixing belt side of a pressure member for forming a nip by pressing the fixing belt against the pressure rotator.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
In general, when considering the heat insulating material or heat insulating layer, how much heat insulating gas such as air or space such as vacuum can be included in addition to the point of material, and convection does not occur in the case of gas The ideal condition for a heat insulating material or heat insulating layer is that it can be accommodated in a minute closed space. The foamed silicone rubber or sponge rubber is an example of a heat insulating material. However, since the foamed rubber is not a complete closed cell aggregate, convection is generated inside, and there is a problem that it does not necessarily have high heat insulating properties. In addition, these materials also have a problem that, in a pressurized state, bubbles are compressed and only a heat insulating property close to that of solid rubber can be obtained.
[0016]
In the heat insulating material containing hollow particles, even if the hollow particles are considered to have zero particle walls, the filling rate is at most 74% (close-packed uniform particles in three dimensions √2π / 6). High heat insulation cannot be obtained. In addition, when the hollow particles are kneaded into the material or used under pressure, the particles are damaged, and high heat insulating properties cannot be obtained.
[0017]
The following publication describes the thermal conductivity in the case where there is a heat flow perpendicular to a solid fiber containing open bubbles and sealed bubbles in the material.
[Non-Patent Document 1]
Heat Transfer Engineering Material Revision 3rd Edition (published by the 2nd edition of 1976, Publisher: Japan Society of Mechanical Engineers), page 264
This Non-Patent Document 1 describes a theoretical formula when the fibers are arranged in a direction orthogonal to the heat transfer direction, and the relationship between the polyimide volume ratio and the thermal conductivity based on the formula is as shown in FIG. For comparison, the case of a hollow fiber having a closed space is plotted together. From this, it will be understood that the thermal conductivity of the hollow fiber is low.
[0018]
  Heat insulating material in fixing device according to the present inventionThen, adjacent hollow fibers are bent or wound around a core material (FIG. 2) so that the outer circumferences come into contact with each other. For example, such an aspect can be obtained by arranging in a spiral shape. By arranging a plurality of hollow fibers to face in the same direction (FIG. 3) or stacking them (FIG. 4), the outer peripheries of adjacent hollow fibers come into contact with each other. In the direction (cross section) perpendicular to the axial direction of the hollow fiber, the contact area between the hollow fibers that can be the main path of heat transfer is small, and the heat conduction is small. Further, convection hardly occurs in a small closed space, and convective heat transfer hardly occurs. Due to these facts, it is possible to obtain a heat insulating layer having excellent heat insulating properties by using hollow fibers. As described above, while the volume content of air in the closed space in the heat insulating layer of the hollow particles is 74% (the presence of air in the non-closed space is large), as can be seen from FIG. The air volume content in the hollow fiber is 91% (π / 2√3), and in the case of the same wall thickness, the hollow fiber can contain more closed space.
[0019]
  The partition which the said hollow fiber can have in a cross section is a thing as shown, for example in FIG. The presence of the partition makes it possible to reduce the closed space and further suppress the occurrence of convection. Even if pressure is applied depending on the material and thickness of the partition, the deformation can be reduced by the rigidity of the partition. The fixing member may be a binder that is interposed between hollow fibers as shown in FIG. 7 and prevents displacement of the hollow fibers. However, as shown in FIG. 8, the fixing member surrounds the outer periphery of the aggregate of adjacent hollow fibers. The surrounding member (bag) may be in contact with the assembly. In the case of such a surrounding member, the fibers are fixed by the bag being crushed at atmospheric pressure, and the overall shape is maintained. In particular, it is suitable for a relatively thick heat insulating layer in which the heat conduction of the bag itself can be neglected. 1-10kg / cm²Conductivity when pressurized withIs0.08 ~ 0.09W / mKis there.
[0020]
In the method for producing a heat insulating material as described above, the first step of arranging the hollow fibers so that the outer peripheries of the adjacent hollow fibers are in contact with each other, and the second step of filling the binder between the hollow fibers, In addition to following the order, they can be performed simultaneously, or a sheet winding method in which a prepreg sheet having a binder attached thereto is prepared and wound, or a filament winding method in which a binder is supplied while winding fibers. The sheet winding method is superior during mass production.
[0021]
In the case of further comprising a step of reducing the internal space of the hollow fiber from the atmospheric pressure and a step of sealing the internal space in a state where the internal space of the hollow fiber is decompressed, the sealing is performed by, for example, an end heat press It is carried out by heat welding.
[0022]
A cylindrical or columnar member having a cylindrical outer layer and an inner layer located on the inner peripheral side thereof, and having a heat insulating layer between the outer layer and the inner layer, wherein the heat insulating layer adjoins the hollow fiber. Constructed so that the outer circumferences of the hollow fibers are in contact with each other, and when an external force acting in a direction to separate the outer circumferences of the adjacent hollow fibers is applied, the outer circumferences of the adjacent hollow fibers are in contact with each other. In the case of a cylindrical or cylindrical heat insulating member, it is not necessary to use a binder or the like as a fixing means by simply winding the hollow fiber firmly. A cylindrical member having a cylindrical outer layer and a columnar inner layer, wherein the inner layer has hollow fibers such that the outer peripheries of adjacent hollow fibers abut against each other, and the outer peripheries of adjacent hollow fibers are separated from each other The same applies to the cylindrical heat insulating member that maintains the state where the outer peripheries of adjacent hollow fibers are in contact with each other when an external force acting on is applied.
[0023]
The above heat insulating material or heat insulating member is preferably used as a fixing device or an image forming apparatus by using at least a part of a heating member such as a fixing member, a pressure member, or a transfer fixing member. Here, the transfer fixing member means a member that heats the toner transferred from the photosensitive member or the intermediate transfer member, and then presses and fixes the toner onto the paper.
[0024]
In the external heating method disclosed in Patent Document 1 described above, the heat of the surface layer actually escapes to the inside that does not require heating or to the pressure roller, etc., so the rise is higher than the theoretical calculation that heats only the surface layer. Return response from time and temperature drop is delayed. Therefore, the use of a heat insulating material, such as providing a heat insulating layer below the surface layer, is preferred. Even if a heat insulating material is used on the pressure side, it can contribute to a high temperature rise without absorbing heat on the fixing side. A structure in which the belt is pressed from the inside by a fixing member or the like for both fixing and pressing is also known, but it is also effective to use a heat insulating layer for the fixing member. However, the well-known foamed silicone rubber contains air and thus has a low thermal conductivity and good heat insulation properties, but is compressed in the nip to reduce the air content, and the thermal conductivity changes and increases. In addition, since the surface is compressed and deformed, high surface pressure cannot be applied; Furthermore, since the radius of rotation changes due to compression, there is a disadvantage that it is not suitable as a driving roller for conveying a recording material at a constant speed. In porous ceramics and porous resins, which are other well-known heat insulating materials, it is difficult to form pores with a uniform and stable distribution, shape, and size, and is known as another heat insulating material. Similarly, it is difficult to uniformly and stably form a fibrous molded body in which heat-resistant fibers are bonded with a binder and there are voids between the fibers. With the heat insulating material or the heat insulating member according to the present invention, the above problems can be solved.
[0025]
A member having the above-described heat insulating material or heat insulating member as a heat insulating layer, a heat insulating pressing member that performs contact pressurization to a high-temperature part, and a rotating body having the above heat insulating material or heat insulating member as a heat insulating layer, and having a room temperature or higher In addition, a heat insulating pressing member that performs rotary contact pressurization, and a pressing member that performs pressure reduction or release when not in use are suitable for application of the heat insulating material or the heat insulating member according to the present invention.
[0026]
As the fiber material constituting the hollow fiber, glass and resin are conceivable, and hygroscopic materials such as polyimide, polyester, polyamideimide, polybenzimidazole are particularly preferable. The thermal conductivity of glass is 0.55 to 0.75 W / mK, and that of resin is 0.12 to 0.25 W / mK. Although it is difficult to deform with glass fiber, in the case of resin fiber, it is possible to give flexibility by reducing the wall thickness, so that it is possible to give necessary elasticity depending on the application. The entire resin fiber layer has a JIS-A rubber hardness of about 60 to 90 Hs.
[0027]
It is preferable if the sealed space in the hollow fiber is filled with a gas having a lower thermal conductivity than air. For example, xenon (thermal conductivity at 0 ° C. and normal pressure: 0.0052 W / mK), krypton (0.0087 W / mK), argon (0.0163 W / mK), carbon dioxide (0.0145 W / mK) ( The thermal conductivity of air is 0.0241 W / mK). And the said enclosed space may be pressure-reduced to 1 Pa or less, and 0.1 Pa or less is desirable.
[0028]
For example, the hollow fiber is assumed to have an outer diameter of 230 μm and an inner diameter of 150 μm, and thus a wall thickness of about 40 μm. The length is 1000 m, for example. Such a hollow fiber may have a partition when viewed in cross section, and the partition has a thickness that can be ignored.
[0029]
The binder as the fixing means is made of, for example, silicone rubber or silicone resin, and has a thermal conductivity of 0.24 W / mk and a JIS-A rubber hardness of about 60 to 90 Hs. The thermal conductivity of the aggregate of hollow fibers fixed with a binder is 0.08 to 0.09 W / mK, which is 1 to 10 kg / cm.²No change even when pressure is applied. Incidentally, the thermal conductivity of the heat insulating material in the conventional silicone sponge configuration is 1 kg / cm.²What was 0.09 W / mk at the time of pressurization was 3 kg / cm²The pressure was 0.11 W / mK at the time of pressurization and 0.23 W / mK at the time of 10 kg / cm2 pressurization, and the sponge was compressed at the time of high pressurization and became equivalent to solid rubber. This is shown in FIG.
[0030]
The hollow fiber assembly fixed with a binder has a hardness of about JIS-A rubber hardness of about 60 to 90 Hs, and is harder than about JIS-A rubber hardness of about 5 to 30 Hs, which is a heat insulating material hardness of a conventional silicone sponge structure.
[0031]
When the surrounding member that surrounds the outer periphery of the adjacent hollow fiber assembly and is in contact with the assembly is a fixing means, it is a film made of a resin such as polyester, polyamide, or polyamideimide, and surrounds the hollow fiber assembly. It is also preferable to depressurize the internal space, that is, the space between the hollow fiber and the surrounding member, and in that case, the resin may be coated with aluminum in order to maintain airtightness. The thickness of the film is, for example, 0.1 to 0.3 mm. The thermal conductivity of the hollow fiber assembly surrounded by the film is 0.06 W / mK, and the hardness of the hollow fiber assembly surrounded by the film is also about JIS-A rubber hardness 60 to 90 Hs.
[0032]
You may have a heat generating member and an electroconductive member in the outer periphery of the aggregate | assembly of an adjacent hollow fiber. The conductive member can be obtained by copper sulfide treatment or silver plating, and the conductive member may be directly joined to the hollow fiber, or may be in a state in which a metal foil, a mesh, or the like is in close contact. At this time, the thickness of the conductive layer is advantageously 0.1 to 30 μm.
[0033]
FIG. 10 shows a depiction when the internal space is sealed in a state where the internal space of the hollow fiber is decompressed, when the hollow fiber itself is sealed, and when the surrounding member surrounding the hollow fiber assembly is sealed. Moreover, the process of the above heat insulation member manufacturing method is illustrated in steps in FIG. If necessary, a step of grinding and polishing the outer diameter can be included in the middle of this step. In addition, the curing of the binder depends on heat, thereby shortening the time. The conductive sheet may be a conductive sheet processed on the outermost hollow fiber sheet. By having the hollow fiber layer directly under the heating element, it is possible to release the moisture from inside the hollow fiber even if moisture rapidly evaporates at the heating element interface.
[0034]
In the cylindrical or cylindrical heat insulating member, adjacent hollow fibers may be wound spirally, or may be substantially orthogonal to or parallel to the axial direction of the cylindrical shape. The heat insulating layer is surrounded and contacted by the outer layer surface and the inner layer surface, so that when an external force acting in the direction of separating the outer circumferences of the adjacent hollow fibers is applied, the outer circumferences of the adjacent hollow fibers are The contact state can be maintained, but when the external force acting in the direction of separating the outer periphery of the adjacent hollow fibers is applied to the outer periphery of the heat insulating layer, the outer periphery of the adjacent hollow fibers is maintained in contact with each other. For this purpose, it is more effective if it is provided with a surrounding member or a binder between the hollow fibers.
[0035]
For example, the outer layer material is silicone rubber or fluororesin, and the inner layer material is metal, glass, or ceramics. And you may provide the heat-generating member and the electrically-conductive member outside the heat insulation layer outer periphery. When such a cylindrical or cylindrical heat insulating member is applied to an image forming apparatus, it can be used as a fixing member.
[0036]
In the method of manufacturing a cylindrical outer layer and an inner layer located on the inner peripheral side thereof, and further a cylindrical or cylindrical heat insulating member having a heat insulating material between the outer layer and the inner layer, a hollow fiber is used as an adjacent hollow fiber. A heat insulating material that maintains a state in which the outer peripheries of adjacent hollow fibers are in contact with each other when an external force acting in a direction to separate the outer peripheries of adjacent hollow fibers is applied. The 1st process arrange | positioned cylindrically on the outer periphery of this, and the 2nd process of arrange | positioning an outer layer on the outer periphery of a heat insulating material are provided. Between the 1st process and the 2nd process, the process of arrange | positioning a heat generating member or a electrically-conductive member on the heat insulating material surface may be included. The process of the manufacturing method of such a heat insulation member is illustrated in steps in FIG.
[0037]
【Example】
The details of the present invention will be described based on examples shown in the drawings. FIG. 13 shows a tandem digital color printer to which the present invention is applied, and the configuration of the entire image forming apparatus is basically the same as that of the conventional one.
[0038]
This color printer can be configured by assembling an image scanner, an automatic document feeder ADF, a sorter, and others (becomes a digital color copier having a composite function). A description of the scanner is omitted. In this color printer, four image forming units are arranged along the belt running side of the transfer belt 10 of the transfer conveyance belt unit, and the image forming unit forms toner images of four colors of yellow, magenta, cyan, and black. (The differences between the colors are represented by a, b, c, and d in the figure). The transfer belt 10 is an endless belt supported by a driving roller 9, a tension roller 13a, and a driven roller 13b. Since the tension roller 13a pushes down the belt 10 with a spring (not shown), the tension of the belt 10 is maintained almost constant. The
[0039]
Each image forming unit has a photosensitive drum 6 as an image carrier. When image data of each color is sent to a writing unit (multi-beam writing) 5, the photosensitive drum 6 is driven by a driving device (not shown). The laser light corresponding to the image information of the color is exposed for each unit on the portion rotated clockwise and uniformly charged by the charging means. The electrostatic latent image formed by this exposure is developed by the developing device 7 to become a toner image and reaches a position facing the transfer belt 10.
[0040]
On the other hand, paper is fed from the paper feed unit 8, and the fed paper is conveyed onto the transfer belt 10 in synchronization with the above-described toner image by the registration roller, and the toner image is transferred by the action of the transfer unit 11. To do.
[0041]
In the case of full-color printing, a yellow toner image formed by the first image forming unit is transferred to the paper, and a magenta component color latent image is formed in the second image forming unit. When a magenta toner image by magenta toner is obtained, the magenta toner image is transferred onto the paper that has been transferred by the first image forming unit and is superimposed on the yellow toner image. Thereafter, image formation is similarly performed on the cyan toner image and the black toner image, and the four color toner images are superimposed on the paper. The paper on which the four color toner images are superimposed is separated from the transfer belt 10 and conveyed to the fixing device 12. Each photosensitive member that has been transferred is removed from the residual toner by the cleaning means, and is prepared for the next subsequent image formation.
[0042]
A monochrome type image forming apparatus is shown in FIG. 14, for example, and the basic configuration is the same as that conventionally known. The photosensitive drum 6 of the image forming unit rotates clockwise, and the charging unit 2 charges the surface of the photosensitive member with a predetermined polarity. The charged surface is irradiated with the beam L emitted from the writing unit 5 and statically charged. An electrostatic latent image is formed. The electrostatic latent image is visualized as a toner image by the developing device 7, and the toner image is transferred onto the paper fed from the feeding unit 8 by the action of the transfer device 3. The sheet on which the toner image has been transferred passes through the fixing device 12 to fix the toner image. On the other hand, the transfer residual toner adhering to the surface of the photoreceptor after the toner image transfer is removed by the cleaning device 4.
[0043]
The main details of the fixing device 12 mounted on these image forming apparatuses are shown in FIG. A fixing roller 21 that is in pressure contact with the pressure roller 20 by a pressure unit (not shown) rotates clockwise in this figure, and a sheet having a toner image to be fixed is transferred to the fixing roller 21 and the pressure roller 20. The sheet is clamped by and conveyed in the left direction in the figure. An oil application roller, a thermistor, a thermal fuse, and a separation claw are disposed around the fixing roller 21, but are not shown for simplicity. A halogen heater 22 is installed inside the fixing roller as a heating means, and is controlled so that the fixing roller reaches a set temperature. The fixing roller 21 is formed, for example, by coating a teflon layer of t = 10 μm as a release layer 24 on the surface of a metal core 23 having a diameter of 30 mm. For example, the pressure roller 20 has an outer diameter of 30 m, and a winder is used to wind a hollow fiber around the metal core 25 so as to form a coiled t = 2 mm layer. FIG. 16 schematically shows the winding image. Actually, as shown in FIG. 17, the layers are wound densely and laminated so as to contact each other. The hollow fiber layer 26 having high rigidity can be formed by tightly winding the hollow fibers. On the hollow fiber layer 26, a silicone rubber layer of t = 1 mm is formed as an elastic layer 27, and a PFA tube of t = 15 μm is coated as a release layer 28 on the surface layer. The elastic layer 27 is provided to form a nip by pressure contact with the hard fixing roller 21, but this elastic layer is indispensable when the pressure contact partner has an elastic layer or is used as a belt support roller. Absent.
[0044]
As described above, hollow fibers are made of polyimide, polyester, polyamideimide, polybenzimidazole, polybenzobisoxazole, polyphenylene sulfite, aramid, alumina, glass, ceramics, metal, etc. In this example, polyimide is adopted in consideration of heat resistance, thermal conductivity of the material itself, and strength. The polyimide hollow fiber is a simple tube as shown in FIG. 18 and has an outer diameter of φ230 μm and an inner diameter of φ150 μm, for example. By tightly winding the hollow fiber, the void inside the hollow fiber and the gap between the hollow fibers are combined. A porosity of 48% is achieved.
[0045]
The surface pressure of the fixing roller 21 and the pressure roller 20 of this configuration is 3 kg / cm.²As a result, the hollow fiber layer 26 hardly deformed and a uniform nip could be formed. In the present invention, a hollow fiber having a thickness of 40 μm is used, but the thinner the thickness, the higher the porosity and the higher the heat insulation performance. On the other hand, since the rigidity becomes weaker as the wall thickness becomes thinner, it is desirable to make the wall thickness as thin as possible within the allowable range of the load applied to the hollow fiber layer 26 and the deformation amount of the hollow fiber layer at that load.
[0046]
FIG. 19 shows another example of a fixing device (second embodiment). The fixing roller 31 and the pressure roller 30 have the same configuration. As schematically shown in FIG. 20, a sheet of hollow fiber knitted in a cloth shape is wound around a metal core 25 to form a hollow fiber of t = 2 mm. Layer 32 is formed. On the hollow fiber layer, a silicone rubber layer of t = 0.3 mm is formed as the elastic layer 27, and the surface layer is covered with a PFA tube of t = 20 μm. A halogen heater 22 is installed above the fixing roller as a heating means, and is covered with a reflection plate 34 so that radiant heat is reflected to the fixing roller side. Since the hollow fiber layer is knitted in a cloth shape, it is not as dense as the first embodiment, and the gaps between the hollow fibers are increased. Since there are many voids, the rigidity is slightly weakened, and when the same load as in the first embodiment is applied, the deformation of the hollow fiber layer becomes slightly large. By forming the nip using this deformation, an equivalent nip can be formed with a thinner elastic layer than in the first embodiment. As shown in FIG. 21, the hollow fiber layer 32 as an elastic layer may be obtained by laminating hollow fibers in random directions and bonding them with a binder.
[0047]
FIG. 22 shows a cross section of an example fixing device (third embodiment) using a belt. The fixing belt 41 is formed by using a belt in which polyimide hollow fibers are knitted endlessly as a base, on which a silicone rubber layer t = 0.2 mm is formed as an elastic layer and a PFA coat layer t = 10 μm is formed as a release layer. The fixing belt 41 is stretched around the first suspension member 42, the driving roller 43, and the support roller 44, and the first suspension member 42 and the driving roller 43 are wound around the pressure roller 40 so as to partially wrap the fixing belt 41. And is in pressure contact with the pressure roller. A halogen heater 22 is provided upstream of the nip as a heat source, and the fixing belt 41 is heated from the surface layer side by using a reflector 34. However, since a hollow fiber layer is used for the belt base, heat insulation is high. The heat does not escape to the suspension member 42, the drive roller 43, and the support roller 44 so much.
[0048]
In such a fixing device configured to wind the fixing belt 41 and form a nip, a wide nip can be formed without applying a large load to the belt suspension member or the pressure roller. In the drive roller 43 and the pressure roller 40, a hollow fiber layer serving as a heat insulating layer is obtained by mixing and molding a hollow fiber having an appropriate length and a binder. Since a high load is unnecessary, the hollow fiber layer itself joined with a binder without a metal core can be used as a roller core. Since no metal core is required, weight reduction is possible. As the binder, rubber, heat-resistant resin, ceramics, cement, and the like can be used. In this example, silicone rubber was used. The rigidity of the hollow fiber layer can be adjusted by adjusting the type of the binder and the mixing ratio of the binder and the hollow fiber.
[0049]
FIG. 23 shows an example of a fixing device using induction heating (fourth embodiment). The fixing roller 51 has a heat-resistant resin roller or glass roller 52 as a core material, and, as shown in FIG. 24, for example, hollow fibers are laminated in parallel with the roller axial direction to form a heat insulating layer 53. This heat insulating layer can naturally be formed by winding a hollow fiber spirally as shown in FIG. 16 or a hollow fiber sheet as shown in FIG. On the hollow fiber layer 53, a silicone rubber layer 0.2 mm as a first elastic layer, a conductive layer 54 in which a PFA tube 20 μm is made conductive with copper sulfide as a heating element, and t = 0.2 mm as a second elastic layer. A silicone rubber layer is formed, and the surface layer is coated with a PFA tube of t = 20 μm. As the conductive layer 54, a nickel sleeve t = 40 μm or the like, or a layer of about 10 μm mainly composed of silver can be used alone or in combination. An induction coil 55 is disposed in the fixing roller 51. The hollow fiber layer is blown by a fan (not shown) so that air flows from one end in the axial direction to the other end. The induction coil 55 becomes less efficient as the temperature rises. Since the hollow fiber layer has good heat insulation, the heat generated by the nickel sleeve is not transmitted to the coil side much, but the heat shielding effect is further improved by flowing air through the hollow fiber layer to remove the heat.
[0050]
The roller core material is not limited to resin, and glass is also suitable in terms of heat resistance and rigidity. It can also be comprised from the composite material of a metal, resin, glass, and a metal. In addition, the conductive layer was not a nickel sleeve, but the outermost hollow fiber formed with a conductive polymer, plated, carbon-containing, or a combination of these showed quick rise characteristics. . Instead of providing the conductive layer 54, the outermost layer of the heat insulating layer 53 is subjected to a conductive treatment, and the conductive layer can be heated by receiving an induced current from the induction coil 55.
[0051]
FIG. 25 shows an example belt fixing apparatus using a fixed pressure member (fifth embodiment). A halogen heater 22 is disposed inside the fixing belt 61 to heat the fixing belt directly. A fixed pressure member inside the fixing belt is pressed against the pressure roller 40 via the fixing belt 61 to form a nip. However, in order to form a nip uniformly without bending, the pressure frame 62 is rigid. It must be a high metal frame and has a large heat capacity. Since the pressure frame 62 is not related to heating, it is not desired to heat it as much as possible. Therefore, a reflector 64 is provided between the halogen heater 22 so that the radiant heat from the halogen heater 22 is not transmitted, and the heat that can be transmitted from the fixing belt 61 at the nip is blocked by the heat insulating material 63 in which hollow fibers are laminated. To do.
[0052]
Each embodiment shows a normal fixing process in which the toner is transferred onto the paper and then heated and fixed. However, the same applies to the transfer and fixing process in which the toner is transferred onto the fixing member and then the heated toner is fixed on the paper. It was effective.
[0053]
【The invention's effect】
  According to the invention of claim 1,The pressure rotator includes a heat insulating layer, and the heat insulating layer includes a resin fiber layer in which outer peripheries of adjacent hollow fibers are in contact with each other, and a binder that fixes the resin fiber layer. -10kg / cm ² The thermal conductivity when pressurized with 0.08 to 0.09 W / mK and the JIS-A rubber hardness is 60 to 90 Hs.Therefore, a heat insulating layer having excellent heat insulating properties can be obtained.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between polyimide volume ratio and thermal conductivity when fibers are arranged in a direction perpendicular to the heat transfer direction.
FIG. 2 is a view showing a state in which a hollow fiber is wound around a core material.
FIG. 3 is a diagram conceptually showing a state in which a plurality of hollow fibers are arranged to face in the same direction.
FIG. 4 is a diagram conceptually showing a state in which a plurality of hollow fibers are laminated.
FIG. 5 is a graph showing the volume content of air in a closed space of hollow particles and hollow fibers.
FIG. 6 is two examples showing a partition of a hollow fiber.
FIG. 7 shows an example in which the fixing member is a binder that is interposed between hollow fibers and prevents displacement of the hollow fibers.
FIG. 8 shows an example in which the fixing member is a surrounding member.
FIG. 9 is a graph showing a change in thermal conductivity with respect to pressure applied in a sponge, solid rubber, and hollow fiber assembly.
FIG. 10 is a diagram depicting an example of sealing a hollow fiber fiber situation and an example of sealing an surrounding member when the internal space is sealed in a state where the internal space of the hollow fiber is decompressed.
FIG. 11 is a diagram showing steps of a heat insulating member manufacturing method step by step.
FIG. 12 is a diagram showing steps of another heat insulating member manufacturing method step by step.
FIG. 13 is an overall configuration diagram of a color image forming apparatus according to the present invention.
FIG. 14 is an overall configuration diagram of a monochrome image forming apparatus according to the present invention.
FIG. 15 is a schematic main view of a fixing device according to the present invention.
FIG. 16 is a schematic view showing an example of winding of a hollow fiber.
FIG. 17 is a partial view of a roller cross section.
FIG. 18 is a perspective view showing an appearance of a hollow fiber.
FIG. 19 is a configuration example of another fixing device.
FIG. 20 is a schematic view showing an example in which a hollow fiber sheet is mounted on a cored bar.
FIG. 21 is a schematic view showing an example in which short fiber hollow fibers are arranged around a cored bar.
FIG. 22 is a configuration example of another fixing device.
FIG. 23 is a configuration example of still another fixing device.
FIG. 24 is a schematic view showing an example in which hollow fibers are arranged along the core metal axis direction.
FIG. 25 is a configuration example of another fixing device.
[Explanation of symbols]
20 Pressure roller
21 Fixing roller
22 Halogen heater
23, 25 Core
24, 28 Release layer
26 Heat insulation layer (hollow fiber layer)
27 Elastic layer

Claims (10)

A fixing rotator having an elastic layer; a pressure rotator that presses against the fixing rotator to form a nip; and a heating unit that heats the fixing rotator. In a fixing device that clamps a sheet with a body and fixes toner on the sheet,
The pressure rotating body includes a heat insulating layer,
The heat insulating layer includes a resin fiber layer in which outer peripheries of adjacent hollow fibers are in contact with each other, and a binder that fixes the resin fiber layer,
The thermal conductivity of the heat insulating layer when pressurized at 1 to 10 kg / cm ² is 0.08 to 0.09 W / mK, and the JIS-A rubber hardness is 60 to 90 Hs. A fixing device. The fixing device according to claim 1,
The fixing device, wherein the resin fiber layer is wound around a core metal of the pressure rotating body. The fixing device according to claim 2,
The fixing device, wherein the resin fiber layer is a sheet obtained by knitting the hollow fiber in a cloth shape. The fixing device according to any one of claims 1 to 3,
The fixing device according to claim 1, wherein the hollow fiber includes a partition in an internal space. In the fixing device according to any one of claims 1 to 4,
A fixing device, wherein an inner space of the hollow fiber is sealed, and xenon, krypton, argon, or carbon dioxide is sealed in a sealed space in the hollow fiber. In the fixing device according to any one of claims 1 to 5,
The fixing device, wherein the heating means is a halogen heater provided inside the fixing rotator. In the fixing device according to any one of claims 1 to 5,
The fixing rotator has a resin fiber layer in which the outer circumferences of adjacent hollow fibers are in contact with each other,
Fixing, wherein the heating means is induction heating means including an induction coil disposed inside the resin fiber layer and a conductive layer provided on the outer periphery of the resin fiber layer. apparatus. In the fixing device according to any one of claims 1 to 5,
The fixing device is characterized in that the heating means is provided outside the fixing rotator, and the fixing rotator includes a resin fiber layer in which the outer circumferences of adjacent hollow fibers are in contact with each other inside the elastic layer. In the fixing device according to any one of claims 1 to 5,
The fixing rotator is a fixing belt, and a heat insulating material is disposed on the fixing belt side of a pressure member for forming a nip by pressing the fixing belt against the pressure rotator. .   An image forming apparatus comprising the fixing device according to claim 1.

Images