JP2004219634A - Heating roller for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the rise time and standby period by enhancing the electro-thermal conversion efficiency of the heat roller of an electrophotographic image forming apparatus. <P>SOLUTION: The heating roller 13 for the image forming apparatus causes a heat generation layer 4 to generate heat by high frequency electromagnetic waves emitted from an IH (induction heating) coil 1 and fixes transferred toner 10 on paper 9 under heat and pressure. In the heat roller 13, the heat generation layer 4 is disposed between the IH coil 1 and a high magnetically permeable resin layer 5 that is a dielectric layer having higher electromagnetic permeability than the heat generation layer 4. High frequency electromagnetic waves emitted from the IH coil 1 are thus concentrated in the heat generation layer 4, thereby enhancing the electro-thermal conversion efficiency and, accordingly, shortening the rise time and standby period of the image forming apparatus. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heating roller of a fixing unit having a function of fixing a toner transferred onto a recording material by heating and pressing in an electrophotographic image forming apparatus such as a laser printer and a copying machine.
[0002]
[Prior art]
Conventionally, in a fixing unit of an image forming apparatus such as an electrophotographic laser printer or a copying machine, a printing material such as a toner is transferred and adhered to a recording medium using a photoconductor or the like and heated and pressed. It is generally performed to fix the image.
[0003]
FIG. 2 is a schematic configuration diagram illustrating an example of a fixing unit of a conventional image forming apparatus. In the fixing section, a halogen lamp 12 is used as a heat source, and the heating roller 13 is heated by turning on the halogen lamp 12 disposed inside the shaft member 6 constituting the heating roller 13. In the case of this image forming apparatus, the apparatus is in a standby state until a temperature required for transferring and attaching a printing material such as the toner 10 is reached. Further, in order to keep the temperature of the heating roller 13 constant, the halogen lamp 12 is repeatedly turned on and off.
[0004]
On the other hand, FIG. 3 is a schematic configuration diagram showing a conventional IH type heating roller. In the fixing unit, a high-frequency electromagnetic wave generated by the IH coil 1 is radiated as a heat source to a heating element that generates heat by induction, and heat generated by eddy current generated in the heating element is used. The heating roller 13 is heated by the heating IH coil 1 disposed inside the shaft core member 6 causing the external heating element (derivative layer 4) to directly generate heat. At this time, in order to keep the temperature of the heating roller 13 constant, the current and frequency applied to the IH coil 1 are adjusted by ON-OFF control or inverter control.
[0005]
In the fixing section of these electrophotographic image forming apparatuses, a printing material such as toner 10 is transferred and adhered to paper 9 and is fixed by heating and pressing. Therefore, a heating roller 13 is required when a fixing operation is requested. It was necessary to wait for the operation to reach the temperature or to perform a preheating operation in which heating was performed in advance in order to reduce the waiting time.
[0006]
Therefore, in recent years, as shown in FIG. 4, in a fixing unit, a high-frequency electromagnetic wave generated by the IH coil 1 as a heat source is applied to a heating element (derivative layer 4) on the heating roller 13. However, in this case, in order to efficiently irradiate the derivative layer 4 with the electromagnetic wave, the derivative layer 4 is formed on the outer peripheral portion of the heating roller 13 which heats and presses the paper 9 on which the printing material such as the toner 10 is transferred and adhered. In some cases, the IH coil 1 is arranged near the dielectric layer 4.
[0007]
Further, the heating means comprises a heating member configured as a cylindrical heat roller made of a material that is heated by eddy current, and an induction heating body that heats the heat roller by induction heating, and the induction heating body is formed on the outer periphery of the heat roller. There is one arranged along a surface (for example, see Patent Document 1).
[0008]
[Patent Document 1]
JP-A-7-295414 (pages 1-5, FIG. 2)
[0009]
[Problems to be solved by the invention]
However, as shown in FIG. 4, the derivative layer 4 is formed on the outer periphery of the heating roller 13 that heats and presses the paper 9 on which the printing material such as the toner 10 is transferred and adhered. In the fixing section in which the coil 1 is arranged, the dielectric layer 4 as a heating element is efficiently electrothermally converted by an eddy current generated by irradiating a high-frequency electromagnetic wave generated by the IH coil 1. Fever. The amount of heat generated at this time is determined by a change in magnetic flux density passing through the dielectric layer 4 and an electric resistance value of the dielectric layer 4 having temperature dependency.
[0010]
For this reason, a magnetic material having a high magnetic permeability is used for the dielectric layer 4. However, such a magnetic material has a relatively high electric resistance value, and the heat resistance increases the electric resistance value and the magnetic characteristics are increased. As a result, the electromagnetic conversion efficiency decreases.
[0011]
On the other hand, when the dielectric layer 4 is formed using a material having a low electric resistance value and a small increase in electric resistance value due to heat generation, such a material has a low magnetic permeability and cannot not only efficiently convert an electromagnetic wave into heat and heat. Since unnecessary magnetism may leak out of the apparatus, it is necessary to shield the leaked magnetism so as not to affect external electronic devices.
[0012]
In addition, in order to effectively use the heat generated in the derivative layer 4, the heat generated in the derivative layer 4 is applied to parts other than the members constituting the fixing unit that heats and presses the paper 9 on which the printing material such as the toner 10 is transferred and adhered. In order to prevent the transmission of the heat, it is necessary that the heating roller 13 has heat insulation performance.
[0013]
Further, the heating roller 13 needs to have a flexibility to reduce a change in pressure that changes due to the shape and thickness of the transfer object and exert sufficient pressure to apply to the transfer object. In order to heat and press the paper 9 to which the printing material has been transferred and attached, the heating roller 13 also needs to have appropriate rigidity. Further, since the heat generating layer, the magnetically permeable layer, the heat insulating layer, and the like constituting the heating roller 13 have greatly different characteristics, it is necessary to form a plurality of different layers using materials and forming methods according to the respective characteristics. There is.
[0014]
SUMMARY OF THE INVENTION It is an object of the present invention to increase the electrothermal conversion efficiency and shorten the startup time and the standby time in a heating roller of an electrophotographic image forming apparatus.
[0015]
[Means for Solving the Problems]
In order to solve this problem, the present invention relates to a heating roller of an image forming apparatus that heats and heats a toner transferred onto a recording material to fix a toner transferred onto a recording material by causing a heating layer to generate heat by high-frequency electromagnetic waves emitted from an IH coil. , The heat generating layer is disposed between the IH coil and a dielectric layer having a higher magnetic permeability than the heat generating layer.
[0016]
Thereby, in the heating roller of the electrophotographic image forming apparatus, the electrothermal conversion efficiency can be increased, and the start-up time and the standby time can be reduced.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
The invention according to claim 1 of the present application is directed to a heating roller of an image forming apparatus that causes a heating layer to generate heat by a high-frequency electromagnetic wave irradiated from an IH coil, and heats and presses and fixes toner transferred onto a recording material. Wherein the heat generating layer is disposed between the IH coil and the derivative layer having a higher magnetic permeability than the heat generating layer, and the high frequency electromagnetic waves emitted from the IH coil are concentrated on the heat generating layer to increase the electrothermal conversion efficiency. It has the action of:
[0018]
The second aspect of the present invention is such that the electric resistance value of the heat generating layer is made smaller than the electric resistance value of the dielectric layer, and has an effect of increasing the amount of heat generated by increasing the current value flowing through the heat generating layer.
[0019]
According to the third aspect of the present invention, the electric resistance value of the heat generating layer is set to be 1.4 × 10 ^{−8 to} 9.0 × 10 ⁻⁸ Ωm, and has an effect of increasing the electrothermal conversion efficiency of the heat generating layer. .
[0020]
According to a fourth aspect of the present invention, a functional layer having at least one of a heat insulating function, a pressure reducing function, and a magnetic shielding function is provided between the heat generating layer and the dielectric layer. It has the effect of exerting a pressure relaxing function and a magnetic shielding function.
[0021]
Hereinafter, an embodiment of the present invention will be described with reference to FIG.
[0022]
(Embodiment 1)
FIG. 1 is a schematic configuration diagram showing a heating roller according to an embodiment of the present invention.
[0023]
As shown in FIG. 1, a magnetic field generated by passing a current through an IH coil 1 is effectively collected by an IH magnetic core 2 formed of a material having a high magnetic permeability, and a high magnetic permeability resin layer serving as a dielectric layer is formed. A magnetic circuit is formed between the heating layer 5 and the magnetic layer 5, and a current is generated in the heating layer 4 by electromagnetic induction generated by a magnetic field passing through the heating layer 4, and heat corresponding to the resistance value of the heating layer 4 is generated.
[0024]
In the heating roller 13, if the shaft core 6 is formed of a non-magnetic material, the shaft core 6 does not generate heat without the high magnetic permeability resin layer 5, but the magnetic flux passing through the heat generating layer 4 is not generated. The heat generation efficiency is greatly reduced. In the present embodiment, since the IH coil 1 and the high-permeability resin layer 5 are arranged so as to sandwich the heating layer 4, high-frequency electromagnetic waves emitted from the IH coil 1 concentrate on the heating layer 4. , High electrothermal conversion efficiency can be obtained. Further, since the electric resistance value of the heat generating layer 4 is smaller than the electric resistance value of the high magnetic permeability resin layer 5, the current flowing through the heat generating layer 4 has a high current value and a large amount of heat is generated.
[0025]
The resin layer 3, which is a functional layer having a heat insulating function, is disposed between the heat generating layer 4 and the high magnetic permeability resin layer 5 so that the heat generated in the heat generating layer 4 does not escape through the shaft member 6. Since the resin layer 3 requires heat resistance and flame retardancy, it is formed using a silicon resin or the like having these properties. Silicon resin exhibits various characteristics depending on the material to be added. In this embodiment, in order to exhibit high magnetic permeability characteristics, a high magnetic permeability material is added by 50% or more of the volume ratio of the silicon resin. Is used.
[0026]
On the other hand, the high-permeability resin layer 5 needs to have high magnetic permeability and not generate heat due to a magnetic field, and therefore needs to be formed of a material having a high electric resistance value. Therefore, iron-nickel-based permalloy metal powder, iron-silicon-aluminum three-element metal sendust material powder, or magnetic metal powder such as iron and nickel, and metal oxide, which are high magnetic permeability materials having high resistance values It is formed using a resin to which ferrite powder or the like made of manganese, zinc, iron, nickel or the like as a raw material is added. Except for the ferrite powder, a fine powder is used because the resistance value is small when the volume is large, and it is necessary that the inside of the resin be in a non-conductive state.
[0027]
Also, in order to provide the high magnetic permeability resin layer 5 with heat insulating performance, a gas such as air or nitrogen, a vacuum inside or a fine capsule in which gas is sealed, a porous material having heat insulating properties, and the like are mixed. Resin can also be used. Even if additives having different properties like these are added, since silicone resin is the main material, they are joined without performing any special bonding work by performing vulcanization and firing after lamination, and a large number of man-hours are added. Not only reduction is possible, but also high quality can be obtained.
[0028]
Next, the heat generating layer 4 is formed of a material having an electric resistance value of about 1.4 × 10 ^{−8 to} 9.0 × 10 ⁻⁸ Ωm, so that the heat generating layer 4 has a relatively small volume. The value of the flowing current can be increased, whereby not only the temperature can be quickly reached to the set temperature, but also the effect that the thickness of the heat generating layer 4 can be greatly reduced can be obtained.
[0029]
As a material having an electric resistance value of about 1.4 × 10 ^{−8 to} 9.0 × 10 ⁻⁸ Ωm, metals such as gold, silver, platinum, copper, and aluminum are preferable. It can be used in the form or as a powder. When used as a powder, it is necessary that they be in a conductive state with each other even in a resin serving as a base material, so that it is necessary to contain 60% or more of a metal powder. If a needle-like or flat metal powder is used, conduction can be obtained at a content of less than 60%.
[0030]
At this time, polyimide or polyether-based resin is used because a resin serving as a base material needs excellent properties of heat resistance and toughness, but these resins are used for the purpose of improving strength. It is also effective to laminate glass-based fibers and carbon-based fibers. Further, a fibrous sheet or mesh made of the above-mentioned metal material can be used in order to increase electric conductivity and obtain strength.
[0031]
Next, the resin layer 3 constituting the heating roller 13 is made of a silicone resin containing air bubbles, a highly flexible resin component, a mixture of a silicone monomer, a silicone oil, and the like, thereby enhancing flexibility and having a pressure relief function. I have.
[0032]
【The invention's effect】
According to the present invention, the following effects can be obtained.
[0033]
(1) According to the first aspect of the invention, the electrothermal conversion efficiency can be increased, and the start-up time and the standby time of the image forming apparatus can be reduced.
[0034]
(2) According to the second aspect of the invention, the amount of heat generated can be increased by increasing the value of the current flowing through the heat generating layer.
[0035]
(3) According to the third aspect of the invention, it is possible to increase the electrothermal conversion efficiency of the heating layer.
[0036]
(4) According to the fourth aspect of the present invention, it is possible to prevent adverse effects due to the leaked electromagnetic waves, enhance the pressing property on the transfer target, and avoid unnecessary temperature rise.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a heating roller according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a conventional halogen lamp type heating roller. FIG. 3 is a schematic diagram showing a conventional IH type heating roller. FIG. 4 is a schematic diagram showing a conventional IH type heating roller.
REFERENCE SIGNS LIST 1 IH coil 2 IH magnetic core 3 resin layer 4 heating layer (derivative layer)
5 High Permeability Resin Layer 6 Shaft Core 7 Release Layer 8 Pressure Roller 9 Paper 10 Toner 11 Separation Claw 12 Halogen Lamp 13 Heating Roller

Claims (4)

A heating roller of an image forming apparatus for heating a heating layer by high-frequency electromagnetic waves irradiated from an IH coil and heating and pressing the toner transferred onto a recording material to fix the toner, wherein the heating layer is formed of the IH A heating roller for an image forming apparatus, wherein the heating roller is disposed between a coil and two or more layers including a derivative layer having a higher magnetic permeability than the heat generating layer. 2. The heating roller according to claim 1, wherein the electric resistance of the heat generating layer is smaller than the electric resistance of the dielectric layer. The heating roller of the image forming apparatus according to claim 1, wherein an electric resistance value of the heat generating layer is in a range of 1.4 × 10 ^{−8 to} 9.0 × 10 ⁻⁸ Ωm. The functional layer according to any one of claims 1 to 3, wherein a functional layer having at least one of a heat insulating function, a pressure relaxing function, and a magnetic shielding function is provided between the heat generating layer and the derivative layer. Heating roller of the image forming apparatus.

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