JP3742807B2 - Fixing roller and fixing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixing device of an image forming apparatus in which a toner image is heated and melted and fixed on a transfer material to form an image, and more particularly to a fixing roller using electromagnetic induction heat and a fixing device using the fixing roller.
[0002]
[Prior art]
As a fixing roller (also called a heating roller) using electromagnetic induction heat generation, for example, there is an induction heat generation roller disclosed in Japanese Utility Model Publication No. 48-59458, and this induction heat generation roller is fixed on the outer surface of the fixed shaft. A coil is wound around the installed iron core, an AC power supply is connected to the coil, and a thin cylindrical rotating heating roller made of a non-magnetic material with high conductivity and high heat conductivity is fixed to the outer peripheral surface of the coil. The magnetic flux leakage of the alternating magnetic flux passing through the iron core that is induced when the coil is energized penetrates the circumferential side wall of the heat generating roller, thereby heating the roller. Yes.
[0003]
JP-A-53-50844 discloses a winding wound around a core made of a magnetic material fixed to a shaft, a heat-resistant heat insulating layer made of an elastic body disposed on the outer periphery of the winding, A technique has been disclosed in which the heating roller is made up of a flexible induction heating layer that covers the heat-resistant heat insulating layer, whereby the heating roller rises quickly and the lack of strength of the heating layer is resolved.
[0004]
[Problems to be solved by the invention]
A heat roller fixing device is generally used as a fixing device of an image forming apparatus using toner, such as an electrophotographic copying machine, a facsimile machine, and a printer. In this heat roller fixing device, a fixing roller having a heat source inside and a pressure roller having a mechanism pressed against the fixing roller are used, and the nip portion formed between the heat roller pair constituted by these is undecided. The toner is heated and melted by passing through the transfer material carrying the attached toner image, and fixed to the transfer material. In general, an infrared heater is used as the heat source for the fixing roller. However, it is inevitable that a part of the input electric power becomes visible light, and the inner wall of the fixing roller that receives infrared light. There is a limit of efficiency due to loss of light reception.
[0005]
On the other hand, as disclosed in Japanese Utility Model Laid-Open No. 48-59458, in the case of using electromagnetic induction heat generation as a heat generating roller, the fixing roller has an outer cylinder that is rotationally driven and an induction heat generated by the outer cylinder. The induction coil is composed of an inner cylinder with an electromagnetic induction heating mechanism, and the induction coil is connected to an AC power supply provided outside, and when the induction coil is excited by the AC power supply, an AC is applied to the inner wall of the outer cylinder. An eddy current is induced, and the vicinity of the inner wall generates heat. In this case, since the outer cylinder itself becomes a heat generation source, it is possible to eliminate a loss as in the case of using an infrared heater.
[0006]
By the way, the heating layer (metal layer) can be thinned in order to accelerate the temperature rise of the fixing roller using electromagnetic induction heat as described above, but the sheet is conveyed by pressing the fixing roller against another roller. In this case, there is a drawback in that it cannot withstand the pressure and hinders sheet conveyance. In order to speed up the rise of the heating roller in the technique described in JP-A-53-50844, which is an invention for improving this drawback and disclosed as a fixing roller (heating roller) using electromagnetic induction heat generation, The heat generation layer is made flexible (thin metal is thinned), and the heat generation layer is supported by an elastic body such as silicone rubber or fluororubber so that it can withstand the pressure when used as a pair of heat rollers. By comprising in this way, it came to be able to shorten rise time, maintaining the function of a heat roller pair.
[0007]
However, by using an elastic body for the support portion of the heat generating layer, the heat generating layer (thin metal layer) is repeatedly fatigued and damaged by pressure, or in a fixing device used for high-speed image formation, a pair of rollers is used. It is inevitable that the heat generation layer plastically deforms and cannot serve as a roller pair due to the extremely high pressure.
[0008]
This invention is made | formed in view of the said situation, Comprising: The subject (object) of this invention is described below.
(1) An object of the present invention is to provide an efficient fixing roller suitable for a pair of heat rollers that does not cause the above-described drawbacks, and a fixing device using the same.
(2) In addition to the object of (1), an object of the present invention is to provide a fixing roller with good exchangeability and a fixing device using the same.
(3) In addition to the object of (2), an object of the present invention is to provide a fixing roller that can further improve the exchangeability and secure the mounting position accuracy, and a fixing device using the same.
(4) In addition to the object of (3), an object of the present invention is to provide a fixing roller capable of simplifying the support method and a fixing device using the same.
(5) An object of the present invention is to provide a fixing roller capable of improving the yield and producing stably when the fixing roller of (1) is produced in large quantities.
(6) In addition to the object of (5), an object of the present invention is to provide a fixing roller having reduced weight and improved handleability.
(7) In the present invention, in addition to the purpose of (6), when the roller is overheated due to a failure of the temperature control mechanism of the fixing device, the roller is damaged, and a pair of hot rollers pressed by high pressure is scattered. An object of the present invention is to provide a fixing roller that can prevent the above-described problem.
[0009]
[Means for Solving the Problems]
As means for solving the above-mentioned problems, a fixing roller according to the present invention includes a magnetic field generating means, a conductive heating layer that is disposed so as to surround the outer periphery of the magnetic field generating means, and generates heat using electromagnetic induction heat generation. The non-conductive and non-magnetic fixed part and the movable part are supported to prevent the conductive heat generating layer, which is inferior in strength, from being deformed, and the outside can be detached from the movable part when detaching. Is.
The fixing roller according to the present invention is configured such that the thermal expansion coefficients of the fixed portion and the movable portion are such that the fixed portion> the movable portion .
More specifically, the fixing roller according to the present invention generates a magnetic field composed of a core made of a cylindrical magnetic body fixed to a shaft and a winding (induction coil) wound around the core. Means (because it has a cylindrical structure, this is called an inner cylinder) and a cylindrical heat generating part that is arranged so as to surround the outer periphery of the magnetic field generating means and generates heat using electromagnetic induction heat generation (the inner cylinder) The heat generating part (outer cylinder) is composed of three layers, a non-conductive heat-resistant support layer, a thin conductive heat-generating layer, and a release layer. It is configured.
[0010]
In the fixing roller according to the present invention, the heat generating part (outer cylinder) having the three-layer structure is integrally formed and is removable (relative to the fixed part side such as the inner cylinder).
[0011]
In the fixing roller according to the present invention, the non-conductive heat-resistant support layer is formed of two bodies, a fixed part and a movable part, and when removing, both parts are divided so that the outside can be detached from the movable part. (Claim 1 ).
In fixing roller according to the present invention further a thermal expansion coefficient of the fixed portion and the movable portion of the non-conductive heat-resistant support layer, and configured such that the fixed portion> the movable portion (claim 2).
Then, the fixing device according to the present invention using a fixing roller having the above configuration.
[0012]
In the fixing roller according to the present invention, the non-conductive heat-resistant support layer is made of a material whose heat-resistant temperature exceeds the temperature load when forming the release layer.
In the fixing roller according to the present invention, the non-conductive heat-resistant support layer is made of a heat-resistant resin.
Furthermore, in the fixing roller according to the present invention, the non-conductive heat-resistant support layer is made of a heat-resistant thermosetting resin such as polyimide resin or polybenzimidazole resin.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an example of the configuration of a fixing device using an induction heating type fixing roller in which the present invention is implemented. 2 is a cross-sectional view showing a cross section orthogonal to the roller axis of the fixing device shown in FIG. The fixing roller 21 includes an outer cylinder 1, an inner cylinder 2, and a rotatable flange 3. The inner cylinder 2 includes an iron core (core) 11 formed integrally with the shaft and an induction coil 12 wound around the iron core 11 to constitute a magnetic field generating means. The induction coil 12 is connected to an AC power supply 15 by a lead wire 14. The outer cylinder 1 which is a heat generating part is disposed concentrically so as to surround the outer periphery of the inner cylinder 2, and flanges 3 are installed on both sides of the outer cylinder 1 and are connected by screws or the like (not shown). The flange 3 is rotatably supported on the shaft of the iron core 11 of the inner cylinder 2 via a bearing 13, and a driving gear (not shown) is provided on one of the flanges, and a motor (not shown) is provided via the driving gear. Connected with. Therefore, the inner cylinder 2 is fixed to the fixing roller 21, and only the outer cylinder 1 is rotated.
[0014]
The pressure roller 22 uses an elastic body such as silicone rubber formed on a core metal, and is brought into contact with the fixing roller 21 with a predetermined pressure to form a heat roller pair, thereby forming a nip portion. The unfixed toner 32 carried on the transfer paper 31 is heated and melted by passing through the nip portion, and is fixed on the transfer paper 31. Temperature detection means 16 such as a thermistor is installed on the outer surface of the fixing roller 21. The surface temperature of the fixing roller 21 is detected by the temperature detection means 16, and the output current of the AC power supply 15 is controlled by a control means (not shown). Thus, the desired temperature is controlled.
[0015]
Here, in the conventional fixing roller using electromagnetic induction heat generation, the outer cylinder 1 of the fixing roller 21 is made of a conductor such as metal, and when the induction coil 12 of the inner cylinder 2 is excited by the AC power source 15, An alternating eddy current is induced on the inner wall of the outer cylinder 1, and the vicinity of the inner wall generates heat due to Joule heat. The generated heat is transmitted toward the outer side of the outer cylinder 1 in the radial direction, and the surface is heated. At this time, since the outer cylinder 1 is thinner, the heat capacity is smaller, so there is an advantage that the start-up time required for heating is reduced. However, when the thickness is reduced, the strength is reduced, and the roller cannot withstand the pressure when being pressed against the pressure roller, so that the roller is deformed, and the transportability of the transfer paper 31 and the fixing property of the toner 32 are hindered. Further, there is a method of supporting a thin outer cylinder with an elastic body, but there are problems described in the section of the problem.
[0016]
Therefore, in the present invention, the outer cylinder 1 constituting the heat generating portion of the fixing roller 21 is configured by three layers of a non-conductive heat-resistant support layer, a thin conductive heat generating layer, and a release layer. That is, by forming the outer cylinder of the fixing roller into a three-layer structure, it is possible to form a fixing roller that is efficient, has a short rise time, and has sufficient structural strength.
Hereinafter, specific examples of the present invention will be described.
[0017]
【Example】
FIG. 3 is a cross-sectional view of the fixing roller showing the first embodiment of the present invention. The outer cylinder 1 of the fixing roller 21 of the present invention includes a nonconductive heat resistant support layer 25, a conductive heat generating layer 26, and a release layer 27. The conductive heat generating layer 26 is made of a conductive material such as a metal thin film or a knitted carbon fiber, and is made thin so as to reduce the heat capacity. The non-conductive heat-resistant support layer 25 serves to support the conductive heat generating layer 26 that is inferior in strength so as not to be deformed, and uses non-conductive and non-magnetic materials such as glass, resin, and ceramics. Further, it is desirable to use a material having a small heat capacity or a material having a small thermal conductivity so as not to disturb the start-up time. As the release layer 27, a thin layer of 10 to 30 μm coated with a fluororesin such as PFA, PTFE, FEP or the like and processed into a tube shape, the toner melted at the nip portion adheres to the roller surface, The problem of so-called offset that adheres to the transfer paper again is prevented.
[0018]
Next, as a second embodiment, the material is selected and processed so that the three layers 25, 26 and 27 constituting the outer cylinder 1 of the fixing roller 2 shown in FIG. Specifically, on the surface of the non-conductive heat-resistant support layer 25, a metal, such as nickel, gold, or silver, is formed as a conductive heat generating layer 26 by a method such as plating, coating, vapor deposition, etc. The mold release layer 27 is formed by using a fine powder of fluororesin such as PFA, PTFE, FEP, etc., which has been coated and fired, or a thin layer tube covered and thermally shrunk. By doing so, the outer cylinder 1 having a three-layer structure can be integrally formed, and can be integrally removed from the flange 3 of the fixing roller 21, and there is no need to separate and remove each layer for replacement. The exchangability during maintenance is improved.
[0019]
Next, FIG. 4 shows a third embodiment. Here, the non-conductive heat-resistant support layer 25 of the outer cylinder 1 of the fixing roller 21 is composed of a fixed portion 251 and a movable portion 252. Then, the fixed portion 251 is fixed to the flange 3 of the fixing roller 21 shown in FIG. 1, and the movable portion 252 is installed on the fixed portion 251. With this configuration, when it is necessary to replace the fixing roller 21 due to the life of the release layer 27, the outer portion can be integrally removed from the movable portion 252, so that the driving portion and the inner cylinder 2 can be removed. There is no need to remove it, improving exchangeability.
[0020]
Next, as a fourth embodiment, in the fixing roller having the configuration shown in FIG. 4, the material of the fixed portion 251 and the movable portion 252 constituting the non-conductive heat-resistant support layer 25 of the outer cylinder 1 is the thermal expansion of the fixed portion 251. A material whose rate is larger than the thermal expansion coefficient of the movable portion 252 is used. For example, when PPS (polyphenyl sulfide) is used for the fixed portion 251 and PI (polyimide) is used for the movable portion 252, it becomes a natural constricting direction due to a temperature rise during use, so there is no need to take a special fixing method. This produces the merit. Furthermore, since the material of the fixed part 251 can be selected from a material having lower heat resistance than the material of the movable part 252, there is an advantage that it can be configured at low cost. Further, since the fixing portion 251 can be kept fixed to the flange 3, if it is attached with high accuracy during manufacturing, the positional accuracy is maintained even if maintenance is performed. This makes it difficult to happen.
[0021]
Next, as a fifth embodiment, in the fixing roller 21 having the configuration shown in FIG. 3, the heat resistance temperature of the non-conductive heat-resistant support layer 25 is set higher than the firing temperature of the fluororesin that forms the release layer 27. As a result, the yield is not reduced due to thermal deformation during manufacturing.
[0022]
Next, as a sixth embodiment, in the fixing roller 21 having the configuration shown in FIG. 3, the material constituting the nonconductive heat resistant support layer 25 is a heat resistant resin. As a result, the weight of the outer cylinder 1 can be reduced, torque fluctuation at the start of driving can be suppressed, and handling at the time of maintenance can be improved.
[0023]
Next, as a seventh embodiment, in the fixing roller 21 having the configuration shown in FIG. 3, the material constituting the nonconductive heat-resistant support layer 25 is thermosetting such as PI (polyimide) resin or PBI (polybenzimidazole) resin. The heat-resistant resin is used. As a result, a very high strength can be maintained in a wide temperature range. For example, even when the temperature of the fixing roller 21 rises abnormally due to a failure of the temperature control mechanism, the roller melts and breaks. There will be no accidents.
[0024]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
That is, in the present invention, the outer cylinder (heat generating portion) of the fixing roller has a three-layer structure of a non-conductive heat-resistant support layer, a thin conductive heat generating layer, and a release layer. A fixing roller having sufficient structural strength was obtained.
[0025]
In the present invention, it is possible to provide a fixing roller with good exchangeability by integrally forming the three-layer structure of the outer cylinder (heat generating portion).
[0026]
In the present invention, a non-conductive heat-resistant support layer is composed of two parts, a movable part and a fixed part, so that the fixing roller can further improve the exchangeability, keep the cost low, and secure the mounting position accuracy. Obtained.
[0027]
In the present invention, since the thermal expansion of the fixed part of the non-conductive heat-resistant support layer is larger than the thermal expansion of the movable part, the roller can be fixed naturally without using a special fixing method. A fixing roller capable of simplifying the supporting method was obtained.
[0028]
In the present invention, the heat resistance temperature of the non-conductive heat-resistant support layer is set to be higher than the firing temperature of the fluororesin. Therefore, when producing a large number of fixing rollers having the above structure, the yield is improved and stable production is achieved. A fixing roller capable of being obtained was obtained.
[0029]
In the present invention, since the material of the non-conductive heat-resistant support layer is made of resin, a fixing roller with reduced weight and improved handleability was obtained.
[0030]
In the present invention, since the material of the non-conductive heat-resistant support layer is a thermosetting resin such as PI or PBI, when the roller is overheated due to a failure of the temperature control mechanism of the fixing device, the roller is damaged and high pressure is applied. A fixing roller that can prevent accidents in which a pair of heated rollers that are pressed in place scatters was obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration example of a fixing device using an induction heating type fixing roller in which the present invention is implemented.
2 is a cross-sectional view illustrating a cross section orthogonal to a roller axis of the fixing device illustrated in FIG. 1;
FIG. 3 is a cross-sectional view of a fixing roller showing an embodiment of the present invention.
FIG. 4 is a perspective view illustrating a configuration example of an outer cylinder of a fixing roller according to the present invention.
[Explanation of symbols]
1 Outer cylinder (heat generating part)
2 Inner cylinder (magnetic field generating means)
3 Flange 11 Iron core (core)
12 Induction coil (winding)
13 Bearing 14 Lead wire 15 AC power supply 16 Temperature detecting means 21 Fixing roller 22 Pressure roller 25 Non-conductive heat resistant support layer 26 Conductive heat generating layer 27 Release layer 31 Transfer paper 32 Unfixed toner 251 Non-conductive heat resistant support layer Fixed part 252 Movable part of non-conductive heat-resistant support layer

Claims (2)

A magnetic field generating means, and a cylindrical heat generating portion that is disposed so as to surround the outer periphery of the magnetic field generating means and generates heat using electromagnetic induction heat generation , wherein the heat generating portion includes a non-conductive heat resistant support layer and a thin layer. In a fixing roller consisting of three layers, a conductive heat generating layer and a release layer,
A fixing roller characterized in that the non-conductive heat-resistant support layer is formed of two bodies of a fixed part and a movable part, and when removing, both parts are divided so that the outside can be detached from the movable part. 2. The fixing roller according to claim 1, wherein the thermal expansion coefficient of the fixed portion and the movable portion of the non-conductive heat-resistant support layer is set so that the fixed portion> the movable portion.

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