JP5863627B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

  As a method for fixing a toner image formed on a recording material such as paper or film in an image forming apparatus such as a printer, a copying machine, or a multifunction device, a heat fixing method in which toner is melted by heat and fixed on the recording material is generally used. Has been used.

  In recent years, a belt system with a small heat capacity has been proposed in order to reduce the warm-up time and save energy. As a heating method, an IH (Induction Heating) method (induction heating method) capable of rapid heating and high-efficiency heating has been proposed.

  In general, a fixing roller in an IH fixing device includes a cored bar, an elastic layer around the cored bar, and an outermost induction heating layer. In such a configuration, the leakage magnetic flux from the induction heating layer passes through the cored bar and the cored bar is heated, and power is consumed wastefully. For this reason, in a certain fixing device, a magnetic layer is provided around the cored bar to shield leakage magnetic flux that enters the cored bar from the induction heating layer (see, for example, Patent Document 1).

International Publication No. 03/039197

  However, as described above, when the magnetic layer is provided around the cored bar, the cost of the fixing device is increased due to factors such as the cost and workability of the magnetic layer itself.

  The present invention has been made in view of the above problems, and an object of the present invention is to obtain a fixing device and an image forming apparatus that suppress induction heating of a core metal at low cost.

  In order to solve the above problems, the present invention is configured as follows.

The fixing device according to the present invention includes a cored bar, an induction heating layer disposed around the cored bar, and a nonmagnetic material having a lower specific resistance than the cored bar and disposed between the cored bar and the induction heating layer. A roller having a metal nonmagnetic metal layer, an induction heating device for induction heating the induction heating layer, a bearing portion of the cored bar, and an end portion of the nonmagnetic metal layer and the bearing portion And a nonmagnetic metal ring made of a nonmagnetic metal having a specific resistance smaller than that of the cored bar, which is disposed at any position and through which the cored bar is inserted .

  Thus, induction heating of the cored bar is suppressed at low cost by using a nonmagnetic metal layer that is easy to process and can be formed at a relatively low cost.

In addition, the fixing device according to the present invention includes a cored bar, an induction heating layer disposed around the cored bar, and is disposed between the cored bar and the induction heating layer and has a lower specific resistance than the cored bar. A roller having a nonmagnetic metal layer made of a nonmagnetic metal, an induction heating device for induction heating the induction heating layer, a bearing portion of the cored bar, and fixed to the bearing unit, through which the cored bar is inserted And a nonmagnetic metal ring made of a nonmagnetic metal having a specific resistance smaller than that of the core metal.

  In addition to the above fixing device, the fixing device according to the present invention may be as follows. In this case, the fixing device further includes a pressure roller. The roller is a fixing roller that nips the recording body together with the pressure roller.

  In addition to the above fixing device, the fixing device according to the present invention may be as follows. In this case, the fixing device further includes a pressure roller and a fixing roller that nips the recording medium together with the pressure roller. The induction heat generating layer is hung on the roller and the fixing roller.

  In addition to the above fixing device, the fixing device according to the present invention may be as follows. In this case, the metal core is made of stainless steel or free-cutting steel, and the nonmagnetic metal layer is made of aluminum, aluminum alloy, copper, or copper alloy.

  An image forming apparatus according to the present invention includes the above-described fixing device.

  According to the present invention, induction heating of the cored bar in the fixing device is suppressed at low cost.

FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of an example of the fixing device according to Embodiment 1 in a direction perpendicular to the axial direction. FIG. 3 is a cross-sectional view in the axial direction of an example of the fixing device according to the first embodiment. FIG. 4 is a diagram for explaining the magnetic flux in the fixing device shown in FIGS. 2 and 3. FIG. 5 is a cross-sectional view in the axial direction of an example of the fixing device according to the second embodiment. FIG. 6 is a cross-sectional view of an example of the fixing device according to Embodiment 3 in a direction perpendicular to the axial direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.

  FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus is an apparatus having an electrophotographic printing function, such as a printer, a facsimile machine, a copying machine, or a multifunction machine.

  The image forming apparatus of this embodiment has a tandem color developing device. The color developing device includes photosensitive drums 1a to 1d, exposure devices 2a to 2d, and developing devices 3a to 3d. The photoconductor drums 1a to 1d are four-color photoconductors of cyan, magenta, yellow, and black. The exposure apparatuses 2a to 2d are apparatuses that form electrostatic latent images by irradiating the photosensitive drums 1a to 1d with laser light. The exposure apparatuses 2a to 2d include a laser scanning unit having a laser diode that is a light source of laser light and an optical element (lens, mirror, polygon mirror, etc.) that guides the laser light to the photosensitive drums 1a to 1d. A device for cleaning the optical element and the like is also provided.

  Further, around the photosensitive drums 1a to 1d, a charger such as a scorotron, a cleaning device, a static eliminator and the like are arranged. The cleaning device removes residual toner on the photosensitive drums 1a to 1d after the primary transfer, and the static eliminator neutralizes the photosensitive drums 1a to 1d after the primary transfer. The charger is provided with a device for cleaning the charger.

  To the developing devices 3a to 3d, toner cartridges filled with toners of four colors of cyan, magenta, yellow, and black are mounted, respectively, and toner is supplied from the toner cartridge, and constitutes a developer together with the carrier. The developing devices 3a to 3d attach the toner to the electrostatic latent images on the photosensitive drums 1a to 1d to form toner images.

  The photosensitive drum 1a, the exposure device 2a, and the developing device 3a develop magenta, and the photosensitive drum 1b, the exposure device 2b, and the developing device 3b develop cyan, the photosensitive drum 1c, and the exposure device. Yellow development is performed by the device 2c and the developing device 3c, and black development is performed by the photosensitive drum 1d, the exposure device 2d, and the developing device 3d.

  The intermediate transfer belt 4 is an annular image carrier that contacts the photosensitive drums 1a to 1d and primarily transfers the toner images on the photosensitive drums 1a to 1d. The intermediate transfer belt 4 is a kind of intermediate transfer member. The intermediate transfer belt 4 is stretched around the driving roller 5 and circulates in the direction from the contact position with the photosensitive drum 1d to the contact position with the photosensitive drum 1a by the driving force from the driving roller 5.

  The transfer roller 6 brings a conveyed recording body (printing paper or the like) into contact with the intermediate transfer belt 4 and secondarily transfers the toner image on the intermediate transfer belt 4 to the recording body. The recording material to which the toner image has been transferred is conveyed to the fixing device 9.

  The roller 7 has a cleaning brush. The roller 7 is brought into contact with the intermediate transfer belt 4 to remove the toner remaining on the intermediate transfer belt 4 after the toner image is transferred to the recording medium.

  The sensor 8 irradiates a predetermined region of the intermediate transfer belt 4 with a light beam and detects reflected light (measurement light) at the time of calibration of toner density and / or gradation, and an electrical signal corresponding to the light amount. Is output.

  The fixing device 9 fixes the toner image on the recording medium by a heat fixing method using induction heating.

  FIG. 2 is a cross-sectional view of an example of the fixing device 9 according to Embodiment 1 in a direction perpendicular to the axial direction. FIG. 3 is a cross-sectional view in the axial direction of an example of the fixing device 9 according to the first embodiment. The fixing device 9 in the first embodiment is of a uniaxial belt type.

  In the fixing device 9 shown in FIGS. 2 and 3, the fixing roller 11 and the pressure roller 12 are arranged in contact with each other, and the induction heating device 13 is arranged around the fixing roller 11.

  In the fixing roller 11, the core metal 21 is a columnar metal member made of, for example, stainless steel (SUS304 or the like) or free-cutting steel (SUM), and a cylindrical nonmagnetic metal is disposed on the outer periphery of the core metal 21. Layer 22 is formed. The core metal 21 may be made of other iron alloys.

  The nonmagnetic metal layer 22 is, for example, a pipe material made of aluminum or copper, and the core metal 21 is press-fitted into the hollow portion of the nonmagnetic metal layer 22 so that the nonmagnetic metal layer 22 is fixed to the core metal 21. The The nonmagnetic metal layer 22 may be made of an aluminum alloy or a copper alloy. Further, an elastic layer 23 made of, for example, silicone sponge and having a predetermined thickness is formed on the outer periphery of the nonmagnetic metal layer 22.

  Furthermore, an induction heating layer 24 having a predetermined thickness made of, for example, nickel is formed on the outer periphery of the elastic layer 23, and a predetermined thickness made of, for example, fluororesin (PFA), on the outer periphery of the induction heating layer 24. The release layer 25 is fixed with silicone rubber having a predetermined thickness. The induction heating layer 24 is induction heated by the induction heating device 13.

  As described above, the nonmagnetic metal layer 22 is disposed between the cored bar 21 and the induction heating layer 24, and has a lower bending resistance than the cored bar 21 but has a lower specific resistance (electric resistance) than the cored bar 21. It is made of metal.

  Further, as shown in FIG. 3, bearing portions 26 are provided in the vicinity of both ends of the cored bar 21. The bearing portion 26 is a stainless steel (SUS304 or the like) bearing.

  In addition, a nonmagnetic metal ring 27 is disposed at any position between the bearing portion 26 of the core metal 21 and the end portion of the nonmagnetic metal layer 22. A cored bar 21 is inserted into a hollow portion of the nonmagnetic metal ring 27 and fixed to the cored bar 21.

  The nonmagnetic metal ring 27 is formed of a nonmagnetic metal having a specific resistance smaller than that of the core metal 21. For example, the nonmagnetic metal ring 27 is made of the same material as the nonmagnetic metal layer 22.

  The fixing roller 11 has such a structure.

  Further, as shown in FIG. 2, the induction heating device 13 includes a bobbin 31, a core 32, and a coil 33 wound around the bobbin 31, and during induction heating (that is, during fixing operation) A current is conducted to the coil 33, and a magnetic flux generated by the current passes through the fixing roller 11.

  Next, the operation of the fixing device 9 will be described.

  During the fixing operation, the fixing roller 11 and the pressure roller 12 rotate, and the induction heating device 13 generates magnetic flux. Accordingly, the fixing roller 11 and the pressure roller 12 nip the recording body 101, and the induction heating device 13 induction-heats the induction heat generation layer 24 of the fixing roller 11.

  Then, the recording body 101 passes between the fixing roller 11 and the pressure roller 12, and the recording body 101 is heated while being pressed, and the toner image on the recording body 101 is fixed.

  FIG. 4 is a diagram for explaining the magnetic flux in the fixing device 9 shown in FIGS. 2 and 3. In addition, the arrow in a figure represents the path | route of magnetic flux.

  At this time, as shown in FIG. 4 (A), out of the magnetic flux from the induction heating device 13, the leakage magnetic flux from the induction heating layer 24 tends to go to the core metal 21, but as shown in FIG. 4 (B). The eddy current in the nonmagnetic metal layer 22 caused by the leakage magnetic flux generates a reverse magnetic flux that reduces the leakage magnetic flux. As a result, the magnetic flux entering the cored bar 21 is reduced.

  Further, as shown in FIG. 4A, the induction heating device 13 does not enter the induction heating layer 24 at the portion where the cored bar 21 is exposed from the end of the induction heating layer 24 to the bearing portion 26 side. However, as shown in FIG. 4B, a reverse magnetic flux that reduces the magnetic flux component by eddy current in the nonmagnetic metal ring 27 due to this magnetic flux component exists. As a result, the magnetic flux entering the core metal 21 is reduced.

  As described above, according to the first embodiment, in the fixing roller 11, the nonmagnetic metal layer 22 made of a nonmagnetic metal having a lower specific resistance than the cored bar 21 between the cored bar 21 and the induction heating layer 24. Is provided. Thereby, the induction heating of the cored bar 21 is suppressed at a low cost by using the nonmagnetic metal layer 22 that is easy to process and can be formed at a relatively low cost.

  As a result, useless power consumption can be reduced, and embrittlement of the elastic layer 23 caused by the temperature rise of the cored bar 21 can be suppressed. In addition, since the specific resistance of the nonmagnetic metal layer 22 is small, generation of Joule heat due to eddy current can be reduced.

  Further, since a magnetic material can be used as the material of the cored bar 21, a material having a high bending strength and a low cost can be used for the cored bar 21, so even if the bending strength of the nonmagnetic metal layer 22 is low. no problem.

  In addition, although it is possible to suppress the induction heating by forming the cored bar 21 with a nonmagnetic metal having a small specific resistance such as aluminum, in that case, it is difficult to obtain the flexural strength, which is not practical.

Embodiment 2. FIG.

  In the image forming apparatus according to the second embodiment of the present invention, the nonmagnetic metal ring in the fixing device 9 is installed at a position different from that in the first embodiment.

  In the second embodiment, a nonmagnetic metal ring 51 similar to the nonmagnetic metal ring 27 is fixed to the bearing portion 26.

  FIG. 5 is a sectional view in the axial direction of an example of the fixing device 9 according to the second embodiment. For example, as shown in FIG. 5, the nonmagnetic metal ring 51 is fixed to the outer periphery of the bearing portion 26.

  Since the other configuration and operation of the image forming apparatus according to the second embodiment are the same as those of the first embodiment, the description thereof is omitted.

Embodiment 3 FIG.

  In the image forming apparatus according to Embodiment 3 of the present invention, a biaxial belt type fixing device 9 is used.

  FIG. 6 is a cross-sectional view of an example of the fixing device 9 according to Embodiment 3 in a direction perpendicular to the axial direction.

  In the third embodiment, the fixing roller 61 nips the recording body 101 together with the pressure roller 62, and another roller 63 around which the belt 71 is laid is provided together with the fixing roller 61. An induction heating device 64 is provided around the roller 63.

  The belt 71 has the same induction heat generating layer and release layer as in the first embodiment. Therefore, the belt 71 (that is, the induction heating layer) is heated on the roller 63 by the induction heating device 64, and the fixing is performed on the fixing roller 61 by the heated belt 71 (that is, the induction heating layer).

  In the roller 63, a nonmagnetic metal layer 73 is formed around the cored bar 72. The metal core 72 and the nonmagnetic metal layer 73 are the same as the metal core 21 and the nonmagnetic metal layer 22 in the first embodiment.

  Further, in the roller 63, a nonmagnetic metal ring similar to the nonmagnetic metal ring 27 in the first embodiment is provided between a bearing portion (not shown) of the core metal 72 and the nonmagnetic metal layer 73.

  Since the other configuration and operation of the image forming apparatus according to the third embodiment are the same as those of the first embodiment, the description thereof is omitted.

  As described above, according to the third embodiment, in the biaxial belt type fixing device 9, induction heating of the core metal 72 of the roller 63 around which the induction heating device 64 is arranged is suppressed at low cost. The

Embodiment 4 FIG.

  In the image forming apparatus according to the fourth embodiment of the present invention, the nonmagnetic metal ring in the biaxial belt type fixing device 9 is installed at a position different from that in the third embodiment.

  In the fourth embodiment, a nonmagnetic metal ring similar to the nonmagnetic metal ring 51 of the second embodiment is fixed to the bearing portion of the core metal 72. For example, the nonmagnetic metal ring is fixed to the outer periphery of the bearing portion.

  Note that other configurations and operations of the image forming apparatus according to the fourth embodiment are the same as those of the third embodiment, and thus the description thereof is omitted.

  Each embodiment described above is a preferred example of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. It is.

  For example, the image forming apparatus in the above-described embodiment is an indirect transfer type color image forming apparatus, but the same configuration is applied to a fixing apparatus such as a direct transfer type image forming apparatus or a monochrome image forming apparatus. Can be applied.

  The present invention is applicable to, for example, an electrophotographic image forming apparatus.

DESCRIPTION OF SYMBOLS 9 Fixing device 11,61 Fixing roller 12,62 Pressure roller 21,72 Core metal 22,73 Nonmagnetic metal layer 24 Induction heating layer 26 Bearing part 27,51 Nonmagnetic metal ring 63 Roller 71 Belt (an example of induction heating layer) )

Claims (6)

A cored bar, an induction heating layer disposed around the cored bar, and a nonmagnetic metal layer made of a nonmagnetic metal having a lower specific resistance than the cored bar, disposed between the cored bar and the induction heating layer. A roller having
An induction heating device for induction heating the induction heating layer;
A bearing portion of the core metal;
A nonmagnetic metal ring made of a nonmagnetic metal having a smaller specific resistance than the cored bar, which is disposed at any position between the end of the nonmagnetic metal layer and the bearing part, and through which the cored bar is inserted. ,
A fixing device comprising: A cored bar, an induction heating layer disposed around the cored bar, and a nonmagnetic metal layer made of a nonmagnetic metal having a lower specific resistance than the cored bar, disposed between the cored bar and the induction heating layer. A roller having
An induction heating device for induction heating the induction heating layer;
A bearing portion of the core metal;
A nonmagnetic metal ring made of a nonmagnetic metal having a lower specific resistance than the cored bar, which is fixed to the bearing portion and through which the cored bar is inserted;
Constant Chakusochi you, characterized in that to obtain Bei the. A pressure roller,
The roller is a fixing roller that nips a recording medium together with the pressure roller;
The fixing device according to claim 1 or claim 2 wherein. A pressure roller;
A fixing roller that nips the recording body together with the pressure roller;
The induction heating layer is hung on the roller and the fixing roller;
The fixing device according to claim 1 or claim 2 wherein. The core bar is made of stainless steel or free-cutting steel,
The nonmagnetic metal layer is made of aluminum, aluminum alloy, copper, or copper alloy,
The fixing device according to any one of claims 1 to 4 , wherein Image forming apparatus characterized by claim 1 comprising a fixing device according to any one of claims 5.

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