JP2011085636A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device for preventing a reduction in lifetime of the fixing device and an increase in size of the device caused by a polishing means, in the fixing device provided with the polishing means. <P>SOLUTION: The fixing device includes: a fixing means configured to fix a toner image on a recording material by heat and pressure, by allowing the sheet-like recording material with an unfixed toner image carried thereon to pass through a fixing nip N formed by press-bonding a pressure roller 16 to a fixing roller 15 through a fixing belt 17; and a polishing mode control means for polishing the surface of the fixing belt 17 by giving a linear speed difference between the fixing belt 17 and the pressure roller 16, for a predetermined time at predetermined timing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fixing device and an image forming apparatus.

  There is a fixing device as one of the constituents of an electrophotographic image forming apparatus. As is well known, this fixing device has an unfixed fixing nip formed by rotatably contacting a pair of rotating bodies composed of a roller-shaped or belt-shaped fixing section and a roller-shaped pressurizing section. The toner image is melted and fixed on the recording material with heat and pressure through a sheet-like recording material carrying the toner image.

  In this fixing device, various recording materials of different sizes, thicknesses, materials, etc. are passed through the fixing nip, so that the surface of the fixing unit is scratched or separated by a separation claw that separates the recording material from the fixing unit. The surface may be scratched, and as a result, streaky uneven gloss may occur in the recording material after fixing.

  In order to solve this problem, for example, there is a technique in which a roller-shaped polishing unit is pressed against a belt-shaped fixing unit and is polished by rotation of the fixing unit (see, for example, Patent Document 1).

The fixing device provided with the above-described polishing means is preferable because even if the surface of the fixing portion is damaged, the fixing device is suitable for immediate removal. However, the polishing means is always in contact with the belt-like fixing portion. Therefore, the life of the release layer, which is the surface layer of the fixing belt, and thus the life of the fixing device is shortened.
Further, since the polishing means is provided outside the fixing belt and protrudes, there is a possibility that the apparatus becomes large. If the polishing means is provided in the belt-like fixing unit so as to be able to advance and retreat, the life of the fixing belt is extended, but the apparatus becomes large.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device and an image forming apparatus that can solve the above-described problems.

In order to solve the above problems, the fixing device and the image forming apparatus according to the present invention employ the following technical means.
According to the first aspect of the present invention, the toner image is transferred by heat and pressure through a sheet-like recording material carrying an unfixed toner image through a fixing nip formed by pressing a pair of rotating members rotatably. Fixing means comprising fixing means configured to be able to fix to a recording material, and polishing mode control means for polishing the surface of the rotating body with a linear velocity difference between the pair of rotating bodies at a predetermined timing for a predetermined time. Features the device.
According to a second aspect of the present invention, in the first aspect, the fixing unit includes a first fixing unit that melts the toner image and closely contacts the recording material, and the pair of rotating bodies. And a second fixing unit that imparts smoothness to the toner image that is in close contact with the recording material via a fixing unit and fixes the toner image on the recording material.
According to a third aspect of the present invention, in the first or second aspect, the predetermined timing is determined in advance by either the number of sheets that have passed the recording material through the fixing nip or the rotation time or the rotational travel distance of the pair of rotating bodies. When it becomes more than the set predetermined value, or when any two of these three combinations exceed the predetermined value, or when all of these exceed the predetermined value It is characterized by.
According to a fourth aspect of the present invention, in the third aspect, the predetermined value is set in plural according to the type of the recording material, the thickness of the recording material, and the size of the recording material, and the polishing mode control means includes: The predetermined value can be appropriately changed in accordance with the change in the type of the recording material, the thickness of the recording material, and the size of the recording material.
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the polishing mode control means is configured to be executable when a fixing operation for passing the recording material through the fixing nip is not executed. It is characterized by that.
According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the polishing mode control unit may cause the pair of rotating bodies to have a linear velocity after the temperature of the fixing unit is set within a predetermined temperature range. A polishing operation for providing a difference is executed.
According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the fixing unit is configured to extend the axial distance of the pair of rotating bodies so that the pressure of the fixing nip can be reduced. The mode control means is characterized in that after the axial distance of the pair of rotating bodies is extended to reduce the pressure in the fixing nip, a polishing operation is performed to give a linear velocity difference between the pair of rotating bodies.
According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the pair of rotating bodies includes the pair of rotating bodies so that a surface of the rotating body on the toner image side of the recording material is polished. The rotator is configured as described above.
According to a ninth aspect of the invention, there is provided an image forming apparatus including the fixing device according to any one of the first to eighth aspects.

  According to the present invention, the fixing device includes the polishing mode control means for polishing the surface of the rotating body by providing a linear velocity difference between the pair of rotating bodies forming the fixing nip at a predetermined timing for a predetermined time. It is possible to eliminate scratches on the surface of the rotating body without shortening the service life, and since the polishing mode control means does not protrude, it is possible to eliminate the possibility that the apparatus becomes large.

1 is a schematic diagram illustrating an outline of an image forming apparatus including a fixing device according to an exemplary embodiment. 1 is a schematic diagram illustrating an outline of a fixing device according to a first embodiment; 2 is a flowchart 1 illustrating an operation of the fixing device according to the first exemplary embodiment; 3 is a flowchart 2 illustrating an operation of the fixing device according to the first exemplary embodiment; FIG. 6 is a schematic diagram showing another aspect 1 of the fixing device according to the first exemplary embodiment; FIG. 6 is a schematic diagram illustrating another aspect 2 of the fixing device according to the first exemplary embodiment; FIG. 3 is a schematic diagram illustrating an outline of a fixing device according to a second embodiment. FIG. 6 is a schematic diagram illustrating another aspect 1 of the fixing device according to the second exemplary embodiment; FIG. 10 is a schematic diagram illustrating another aspect 2 of the fixing device according to the second exemplary embodiment;

An embodiment of an image forming apparatus provided with a fixing device according to the present invention will be described.
The image forming apparatus according to the present embodiment exemplifies a so-called in-body discharge type image forming apparatus capable of full color output, in which a discharge tray portion 1 is provided in the middle of the side surface of the casing. Before describing the embodiments, first, an outline of the components related to image formation common to the embodiments will be described.

  The image forming apparatus according to the present embodiment is a device in which a middle part of one side surface is formed in a substantially U shape inwardly, and a paper discharge tray unit 1 is provided, and each component unit is supported inside. A frame 2, an opening / closing door 3 provided on the top surface portion of the device machine frame 2 so as to be opened and closed, and a document glass 4 provided in the top surface portion of the device machine frame 2, are placed on the document glass 4. An image reading unit 5 that optically reads an image of a document, a plurality of paper feed trays 6 provided at the lower part of the apparatus, and a photoconductor provided at an intermediate part of the apparatus and based on image data read by the image reading unit 5 7, a plurality of image forming units 8 that form toner images, an intermediate transfer belt 9 that transfers and conveys the toner image formed on the photoconductor 7, and a sheet that is conveying the toner image conveyed by the intermediate transfer belt 9. Transfer portion 10 to be transferred to a sheet-like recording material, and the transfer portion A registration roller 11 that feeds a sheet-like recording material at a predetermined timing toward 0, a fixing device 12 that is provided in the vicinity of the transfer unit 10 and fixes the toner image to the sheet-like recording material, a plurality of guide plates, The sheet-shaped recording material is conveyed from the sheet feeding tray 6 to the sheet discharge tray 1 via the transfer unit 10 and the fixing device 12 and includes a conveying roller, a switching claw, a pair of sheet discharge rollers 14, and the fixing device. And a recording material conveyance unit 13 that conveys the sheet-shaped recording material that has come out of the sheet 12 while being reversed to the transfer unit 10 again.

  In the image forming apparatus configured as described above, a plurality of image forming units 8 are provided on each photoconductor 7 based on image data generated by the image reading unit 5 reading an image of the document placed on the document glass 4. Toner images corresponding to the color (yellow, magenta, cyan, black) are formed and transferred to the intermediate transfer belt 9 so that the toner images of the respective colors overlap, and the intermediate transfer belt 9 transfers the toner image to the transfer unit 10. Transport.

  On the other hand, the sheet-like recording material in the paper feed tray 6 starts to be conveyed by the recording material conveyance unit 13, and the registration roller 11 sandwiches and waits. The registration roller 11 sends the sheet-like recording material to the transfer unit 10 at a predetermined timing immediately before the toner image is positioned on the transfer unit 10, so that the toner image is transferred to the sheet-like recording material by the transfer unit 10. . The sheet-like recording material carrying the toner image is moved to the fixing device 12 by the recording material conveying unit 13, and the fixing device 12 applies heat and pressure to the sheet-like recording material carrying the toner image to form the toner image. Fix to sheet-like recording material. The paper discharge roller 14 discharges the sheet-like recording material on which the toner image has been fixed discharged from the fixing device 12 toward the paper discharge tray unit 1. The sheet-like recording material for single-sided printing is discharged to the paper discharge tray unit 1 with the image forming surface facing downward.

Next, the fixing device which is the main part of the present invention will be described in detail.
(Embodiment 1)
As shown in FIG. 2, the fixing device 12 according to the first exemplary embodiment includes a fixing unit and a polishing mode control unit 26.
The fixing unit includes a fixing roller 15, a heating roller 16, a fixing belt 17, a heat source 18, a pressure roller 19, a driving unit, and a fixing temperature control unit 22. The fixing roller 15, the heating roller 16, and the fixing belt 17 constitute a fixing unit, the pressure roller 19 includes a pressing unit, and the fixing unit and the pressing unit are paired with each other. A rotating body is formed.

  The fixing roller 15 is provided with a highly heat-insulating elastic layer made of foamed silicon rubber or the like on a core metal such as aluminum, stainless steel, or iron, and is rotatably supported by a machine frame of the fixing device 12. Yes. As described above, by using the foamed silicon rubber for the elastic layer, it is possible to reduce the thermal conductivity, prevent the movement of heat from the fixing belt 17 described later, and reduce the apparent heat capacity. As specific dimensional values of the fixing roller 15 in the radial direction, the outer diameter is 30 to 50 mm, and the elastic layer is 2 to 15 mm.

  The heating roller 16 is formed of a non-magnetic material such as stainless steel (for example, SUS304) in a thin cylindrical shape capable of ensuring a required strength, and a core made of a ferromagnetic material such as ferrite faces a heat source 18 described later. In the cylinder, the machine frame of the fixing device 12 is rotatably supported at a position away from the fixing roller 15 by a predetermined distance. By forming the heating roller 16 into a thin cylindrical body having a required strength, the heat capacity is reduced, and the temperature can be raised to a desired temperature in a short time. As specific dimensional values of the heating roller 16 in the radial direction, the outer diameter is φ15 to 25, and the thickness of the cylinder is 300 to 1000 μm.

  The fixing belt 17 has a multilayer structure in which an elastic layer made of silicon rubber or the like is provided on a base layer made of polyimide resin or the like, and a release layer (surface layer) made of a fluorine compound or the like is further provided thereon. And endlessly hangs around the fixing roller 15 and the heating roller 16. With the above-described release layer, releasability with respect to the toner is ensured. Specific dimension values of the fixing belt 17 are 50 to 200 μm for the base layer, 70 to 300 μm for the elastic layer, and 5 to 50 μm for the release layer.

  The heat source 18 is configured by incorporating an IH coil in a horseshoe-shaped frame, and is provided so as to cover the half circumferential surface of the heating roller 16 opposite to the fixing roller 15 side. The heat source 18 configured in this manner heats the heating roller 16 by inductively heating the core by energizing the IH coil. The heat of the heating roller 16 is transmitted to the fixing belt 17.

  The pressure roller 19 is provided with a high elastic layer made of fluorine rubber, silicon rubber or the like on a core metal such as aluminum, stainless steel, or iron, and further, a release layer made of fluorine compound or the like is further provided thereon. Thus, the elastic layer of the fixing roller 15 is rotatably supported by a link mechanism (not shown) attached to the machine frame of the fixing device 12 so that the elastic layer of the fixing roller 15 is elastically deformed with the fixing belt 17 interposed therebetween. A portion where the fixing roller 15 and the pressure roller 19 are in pressure contact with each other with the fixing belt 17 interposed therebetween is a fixing nip N. As specific dimensional values of the pressure roller 19 in the radial direction, the outer diameter is φ30 to 50, the elastic layer is 1 to 10 mm, and the release layer is 5 to 50 μm.

  A guide plate 20 for guiding the conveyance of the recording material is provided on the inlet side of the fixing nip N, and the conveyance of the recording material is guided on the outlet side of the fixing nip N so that the recording material is fed from the fixing belt 17. A separation claw 21 that facilitates separation is provided.

  The drive unit (not shown) includes a first gear provided on the pressure roller 19, a drive motor M having a pinion gear meshed with the first gear, and an inner ring (clutch C) Of the clutch C, the second gear attached to the outer ring of the clutch C and meshed with the first gear, the pressure roller 19 is rotatably supported, and the fixing roller 15 is pressurized. And a link mechanism configured to be able to advance and retract the roller 19 (can extend the axial distance of the pair of rotating bodies). Note that the numbers of teeth of the first gear and the second gear described above are different even when the outer diameter of the fixing roller 15 and the outer diameter of the pressure roller 19 are the same.

  In the drive unit configured as described above, during the normal fixing operation, the rotation of the pinion gear by the drive motor M is transmitted to the first gear, the pressure roller 19 rotates, and the rotation of the first gear is transmitted. The second gear rotates idly by the clutch C (the clutch C is disengaged), and the fixing roller 15 is rotated by the pressure roller 19 via the fixing nip N.

  In a polishing mode, which will be described later, the clutch C is engaged, and the pressure roller 19 is forcibly rotated by the drive motor M via the first gear, the second gear, and the like. At this time, the number of teeth of the first gear and the second gear is different (or the number of teeth is different and the outer diameter of the fixing roller 15 and the pressure roller 19 is different). There is a difference between the speed and the linear speed of the pressure roller 19, and slip occurs in the area of the fixing nip N. As a result, scratches on the fixing belt 17 that affect the image quality are polished and leveled. The linear velocity difference at this time is preferably around 5% from the experimental results.

The fixing temperature control unit 22 includes an IH control unit 23 and a fixing control unit 24.
The IH control unit 23 includes an inverter circuit for induction heating, and is electrically connected to the heat source 18, a power source, and a fixing control unit 24 described later.
The fixing control unit 24 is electrically connected to a thermistor 25 provided to be able to detect the temperature of the fixing belt 17, a power source, and the IH control unit 23, and the temperature of the fixing belt 17 is based on the temperature detected by the thermistor 25. The heat source 18 is controlled via the IH control unit 23 so that the temperature becomes a predetermined fixing temperature.

  The polishing mode control means 26 includes means (not shown) for detecting physical quantities such as the number of sheets (the number of fixed sheets) passed through the fixing nip N (the number of fixed sheets), the rotation time of the fixing belt 17 and the rotational travel distance. In the predetermined time, the drive unit is controlled so that a linear velocity difference is provided between the fixing belt 17 and the pressure roller 19 as a pair of rotating bodies, and the surface of the fixing belt 17 is mainly polished (polishing mode). )

  The predetermined timing is a separation claw for scratching the surface of the fixing belt 17 by passing various recording materials of different sizes, thicknesses, materials, etc. through the fixing nip N or separating the recording material from the fixing belt 17. 21, the surface of the fixing belt 17 may be scratched, but the number of sheets that have passed the recording material through the fixing nip N immediately before the recording material after fixing appears as streaky uneven gloss (the number of fixings). The rotation time and the rotation travel distance of the fixing belt 17 are stored in advance as a predetermined value X, and all of the detected number of sheets, the rotation time of the fixing belt 17 and the rotation travel distance are detected each time. It is assumed that the value exceeds X (preset).

  As another example of this predetermined timing, a configuration using any two of these three of the number of sheets (integrated number) passed through the fixing nip N, the rotation time of the fixing belt 17 and the rotation travel distance is used. Or any one of them may be used.

Next, the operation by the polishing mode control means 26 of the fixing device 12 according to the first embodiment configured as described above will be described with reference to FIG.
First, a fixing operation for allowing the recording material to pass through the fixing nip N is started (S11). Each time, the number of sheets (fixed number of sheets) passed through the fixing nip N, the rotation time of the fixing belt 17, and the rotational travel distance are set. A physical quantity is detected (S12).

Each physical quantity is compared with a predetermined value X corresponding to each physical quantity (S13), and when all the physical quantities exceed the predetermined value X (S13; Yes), the mode is shifted to the polishing mode and the drive unit is controlled. Then, a linear speed difference is generated between the fixing belt 17 and the pressure roller 19 for a predetermined time (S14). When this polishing operation is completed, the physical quantities of the number of recording materials passed through the fixing nip N (fixed number of sheets), the rotation time of the fixing belt 17 and the rotational travel distance are initialized (S15). Prepare for fixing operations.
In S13, when all the physical quantities do not exceed the predetermined value X (S13; No), it is determined that there is no need to shift to the polishing mode, and the next fixing operation is prepared.

  As described above, according to the first embodiment, the polishing mode control unit 26 mainly polishes the surface of the fixing belt 17 by giving a linear velocity difference between the fixing belt 17 and the pressure roller 19 at a predetermined timing for a predetermined time. With this, it is possible to eliminate the scratches on the surface of the fixing belt 17 without shortening the life of the fixing device 12, and in addition, the linear velocity difference between the fixing belt 17 and the pressure roller 19 can be reduced. Therefore, the surface of the fixing belt 17 is mainly used as a means for polishing (polishing mode control means 26). Therefore, the polishing mode control means 26 does not physically protrude, and the risk of an increase in the size of the apparatus is eliminated. it can.

  The first embodiment described above exemplifies the case where all physical quantities exceed the predetermined value X and immediately shift to the polishing mode. However, in addition to this, for example, the number of printed sheets is plural, and during the printing When all the physical quantities exceed the predetermined value X, the mode is shifted to the polishing mode when all the printing is completed, or the mode is shifted to the polishing mode when the image forming apparatus is in the sleep mode. It is possible to temporarily suspend the transition to the polishing mode, such as shifting to the polishing mode at the time of up, and then shift to the polishing mode after it does not interfere with the use of the image forming apparatus by the user. In this case, usability is improved.

  Further, in the example of the polishing mode control means 26 described above, the temperature control and the polishing mode of the fixing belt 17 are independently operated, but in order to reduce the polishing time by reducing the hardness of the surface layer of the fixing belt 17. In order to reduce the hardness of the surface layer of the fixing belt 17 by raising the temperature of the fixing belt 17 to a predetermined temperature in cooperation with the fixing temperature control means 22 (so that the polishing time is not prolonged), the mode is shifted to the polishing mode. May be.

(Embodiment 2)
The second embodiment is a modification of the polishing mode control means 26 exemplified in the first embodiment. In other words, in addition to the configuration of the polishing mode control unit 26 according to the first embodiment, the polishing mode control unit according to the second embodiment sets the predetermined value X to the type of recording material, the thickness of the recording material, and the size of the recording material. In this example, a plurality of values are set in accordance with the recording material type, the thickness of the recording material, and the size and size of the recording material, and the predetermined value X can be changed as appropriate.

For example, when the recording material is thick, the fixing belt 17 (FIG. 2) is greatly damaged at the edge of the recording material, or recording materials of the same width are continuously fed to the fixing nip N (FIG. 2). When the recording material is passed through and when the recording material having different widths is continuously passed through the fixing nip N, in the former case, a flaw is quickly generated at a predetermined position of the fixing belt 17, or even with the same width and thickness. Since the damage received by the fixing belt 17 varies depending on the stiffness of the recording material and the like, there are various values depending on the recording material. In addition to the rotation time of the fixing belt 17 and the rotational travel distance, a plurality of recording materials are set according to the type of recording material, the thickness of the recording material, and the size of the recording material. Whether to migrate or not In addition to changing the predetermined value X, the operating time in the polishing mode is lengthened depending on conditions.
By configuring in this way, the reliability as an apparatus for polishing scratches is improved as compared with the first embodiment.

(Embodiment 3)
In the third embodiment, in addition to the configuration exemplified in the first or second embodiment, the pressure roller 19 (FIG. 2) is rotatably supported, and the pressure roller 19 is advanced and retracted with respect to the fixing roller 15 (FIG. 2). This is an example in which a link mechanism that is configured to operate is operated in conjunction with a polishing mode.

  The operation of the polishing mode control means of the fixing apparatus according to the third embodiment will be described with reference to FIG. 4. First, a fixing operation for passing the recording material through the fixing nip is started (S31), and the fixing is performed each time. Physical quantities such as the number of sheets passed through the nip N (fixed number of sheets), the rotation time of the fixing belt, and the rotational travel distance are detected (S32).

  Each physical quantity is compared with a predetermined value X corresponding to each physical quantity (S33), and when all the physical quantities exceed the predetermined value X (S33; Yes), the process proceeds to the polishing mode. Then, the pressure of the fixing nip N (FIG. 2) is lowered by operating the link mechanism so that the pressure roller 19 (FIG. 2) moves backward from the fixing roller 15 (FIG. 2) (S34). After the predetermined amount has decreased, the drive unit is controlled to generate a linear speed difference between the fixing belt and the pressure roller for a predetermined time (S35). When this polishing operation is completed, the physical quantities of the number of recording materials passed through the fixing nip (fixed number of sheets), the rotation time of the fixing belt, and the rotational travel distance are initialized (S36). Prepare for.

In S33, when all the physical quantities do not exceed the predetermined value X (S33; No), it is determined that there is no need to shift to the polishing mode, and the next fixing operation is prepared.
With this configuration, the burden on each component is reduced, and improvement of the polishing state (surface roughness of the fixing belt 17) can be expected by gradually and gently grinding the fixing belt.

(Embodiment 4)
In the fourth embodiment, among the configurations of the first to third embodiments, the fixing belt 17 and the pressure roller 19 (see FIG. 2) are surely polished so that the surface of the fixing belt 17 (FIG. 2) that greatly affects the image quality is polished. 2) is optimized.
That is, the surface roughness of the release layer (surface layer) of the fixing belt 17 and the release layer (surface layer) of the pressure roller 19 is made different. For example, the release layer of the fixing belt 17 is made of PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) which is a normal fluorine resin, and the release layer of the pressure roller 19 is made of carbon and fluorine resin. By adding the filler, the surface roughness of each surface layer can be varied. The pressure roller 19 composed of carbon filler has a rougher surface roughness, and in the polishing mode, the flaws on the release layer of the fixing belt 17 on the image surface side during fixing can be more efficiently polished.

  As the fixing device 12 of the first to fourth embodiments described above, the fixing device 17 of the fixing belt 17 type in which the heat source 18 is an induction heating type is exemplified. However, the fixing device 12 can be applied to, for example, the fixing device shown in FIGS. It is. The fixing device shown in FIGS. 5 to 9 will be described below. Note that the same reference numerals as those in the first embodiment are assigned to components common to the first embodiment.

The fixing device 27 shown in FIG. 5 uses a halogen heater 28 in the heating roller 16 instead of a heat source in which an IH coil is incorporated. In this case, as a matter of course, the IH control unit 23 including the inverter circuit for induction heating is not necessary.
A fixing device 29 shown in FIG. 6 is a fixing roller type fixing device instead of the fixing belt type fixing device, and the heat source 18 includes an IH coil incorporated therein. Although not shown, a fixing roller type fixing device may be used, and a halogen heater 28 may be used as the heat source 18 in the fixing roller 15.

  Furthermore, in the fixing device, as shown in FIGS. 7 to 9, a first fixing unit that melts a toner image and adheres to the recording material, and a toner that adheres to the recording material via the first fixing unit Some include a second fixing unit that imparts smoothness to an image and fixes the image on a recording material. In this case, the second fixing unit that greatly affects the image quality is constituted by a pair of rotating bodies, and the second fixing unit is controlled by the above-described polishing mode control unit.

  The fixing device 30 shown in FIG. 7 has the same configuration as that of FIG. 5 as the first fixing unit 31, the second fixing unit 32, and the fixing roller having the halogen heater 28 as the heat source 18 provided therein. And a pressure roller 40 brought into pressure contact with the gloss applying roller 39, and the second fixing unit 32 is controlled by the above-described polishing mode control unit 26. Control is performed. The configuration of the gloss imparting roller 39 and the pressure roller 40 is as follows.

  The gloss imparting roller 39 is provided with a highly heat-insulating elastic layer made of foamed silicon rubber or the like on a core metal such as aluminum, stainless steel, or iron, and a release layer made of a fluorine compound or the like on the elastic layer. A surface layer) and is rotatably supported by the machine frame of the fixing device. Specific dimensional values of the gloss imparting roller in the radial direction are an outer diameter of φ30 to 50, an elastic layer of 0.5 to 5 mm, and a release layer of 5 to 50 μm.

  The pressure roller 40 is provided with an elastic layer made of fluorine rubber, silicon rubber or the like on a core metal such as aluminum, stainless steel, or iron, and a release layer (surface layer) made of a fluorine compound or the like thereon. ) And is rotatably supported by the machine frame of the fixing device. As specific dimension values of the pressure roller 40 in the radial direction, the outer diameter is φ30 to 50, the elastic layer is 1 to 30 mm, and the release layer is 5 to 50 μm.

  In the fixing device 33 shown in FIG. 8, both the first fixing unit 34 and the second fixing unit 35 are configured by the fixing unit having the same configuration as that in FIG. Control by the above-described polishing mode control means is performed.

In the fixing device 36 shown in FIG. 9, the first fixing unit 37 is configured by a fixing unit having the same configuration as in FIG. 5, and the second fixing unit 38 is connected to the fixing roller 15 configuring the fixing unit in FIG. Instead, a pair of small-diameter fixing rollers 41 and 42 is used, and one fixing roller 42 on the downstream side of the recording material conveyance is used as a driving roller by the driving motor M, and the above-described polishing mode control unit 26 is used as the second fixing unit 38. It is equipped with.
As described above, any fixing device can be applied as long as the fixing device is configured to form the fixing nip N with a pair of rotating bodies.

  The embodiment of the image forming apparatus provided with the fixing device according to the present invention has been described above. However, the above-described embodiment shows an example of a preferred embodiment of the present invention. The present invention is not limited, and various modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 12 ... Fixing device 15 ... Fixing roller 16 ... Heating roller 17 ... Fixing belt 18 ... Heat source 19 ... Pressure roller 20 ... Guide plate 21 ... Separation claw 22 ... Fixing temperature control means 23 ... IH control part 24 ... Fixing control part 25 ... Thermistor 26. Polishing mode control means 28 Halogen heater N Fixing nip M Drive motor C Clutch

JP 2006-317881 A

Claims (9)

A sheet-like recording material carrying an unfixed toner image is passed through a fixing nip formed by pressing a pair of rotating members in a rotatable manner, and the toner image can be fixed to the recording material with heat and pressure. Fixing means,
A fixing device comprising: a polishing mode control unit configured to polish a surface of the rotating body with a linear velocity difference between the pair of rotating bodies at a predetermined timing for a predetermined time. The fixing means is
First fixing means for fusing the toner image and closely contacting the recording material;
And a second fixing unit that includes the pair of rotating members and adds smoothness to the toner image that is in close contact with the recording material via the first fixing unit and fixes the toner image to the recording material. The fixing device according to claim 1.   The predetermined timing is determined when either the number of sheets that have passed the recording material through the fixing nip or the rotation time or the rotational travel distance of the pair of rotating bodies is equal to or greater than a predetermined value, or 3 3. The fixing device according to claim 1, wherein one of two arbitrary combinations is equal to or greater than the predetermined value, or all are equal to or greater than the predetermined value. A plurality of the predetermined values are set according to the type of the recording material, the thickness of the recording material, and the size of the recording material,
The polishing mode control means is configured such that the predetermined value can be appropriately changed according to a change in the type of the recording material, the thickness of the recording material, and the size of the recording material. Item 4. The fixing device according to Item 3.   5. The fixing device according to claim 1, wherein the polishing mode control unit is configured to be executed when a fixing operation for passing the recording material through the fixing nip is not executed. 6. .   6. The polishing mode control unit according to claim 1, wherein after the temperature of the fixing unit is set within a predetermined temperature range, a polishing operation is performed to give a linear velocity difference between the pair of rotating bodies. The fixing device according to claim 1. The fixing unit is configured to extend the axial distance of the pair of rotating bodies so as to reduce the pressure of the fixing nip.
The polishing mode control means executes a polishing operation for extending the axial distance of the pair of rotating bodies to reduce the pressure of the fixing nip and then causing the pair of rotating bodies to have a linear speed difference. The fixing device according to any one of claims 1 to 6.   8. The pair of rotating bodies is configured such that, of the pair of rotating bodies, a surface of the rotating body on the toner image side of the recording material is polished. The fixing device according to claim 1.   An image forming apparatus comprising the fixing device according to claim 1.

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