JP2975435B2 - Fixing device, heated rotator and method of manufacturing the heated rotator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an electrophotographic apparatus, a heating rotator, and a method of manufacturing the heating rotator.

[0002]

2. Description of the Related Art As a fixing device for fixing an unfixed toner image on transfer paper in an apparatus utilizing an electrophotographic process, such as an electrophotographic copying machine, an electrostatic printer, and a facsimile, a mold is released from the surface of a cylindrical metal core. A heating roller formed with a conductive resin film, and a pressure roller which is in pressure contact with the heating roller and has an elastic body layer on its surface. A transfer sheet carrying an unfixed toner image in a nip portion between the pressure roller and the heat roller is used to heat and fix the toner image to the transfer sheet surface by applying heat and pressure so that the toner image surface contacts the heating roller. Roller fixing devices (fixing devices) are widely used.

Conventionally, as a heating method of a heating roller of this type of fixing device, a halogen lamp is inserted as a heat source into a hollow portion of a hollow cored bar of the heating roller, and a thermistor is provided in contact with or close to the surface of the heating roller. In general, a method of detecting the surface temperature of the heating roller and controlling the power supply of the halogen lamp to on / off to maintain the surface of the heating roller at a predetermined fixing temperature is generally adopted.

However, in this method, it takes several minutes for the heating roller surface temperature of the fixing device to reach a predetermined fixing temperature after the power supply of the apparatus main body is turned on. There was a drawback that a device was required and the mechanism was complicated. Further, in this method, the temperature control accuracy is poor and the image quality is unstable, which causes a remarkable drop in the temperature of the heating roller, especially during continuous paper feeding, causing problems such as a decrease in the fixing rate.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the conventional fixing device of the above-mentioned type, the present invention requires a heating roller to reach a predetermined fixing temperature in a short time and requires a complicated control device. It is an object of the present invention to provide a fixing device, a heating rotator, and a method of manufacturing the heating rotator, which enable high-precision temperature control without causing a decrease in roller surface temperature even during continuous paper feeding.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a heating rotator and a pressure rotator pressed against the heating rotator, wherein the heating rotator reaches a predetermined fixing temperature. Then, in a fixing device in which the transfer paper carrying the unfixed toner on the surface is passed through the nip portion of the pair of rotating members so that the toner carrying surface is in contact with the heating rotating member, and the fixing is performed, a high frequency power supply is used. A high-frequency induction heating device including an induction heating coil to which a voltage is applied; and a heating layer having magnetism provided on the heating rotator, wherein the heating layer has a Curie point substantially set to the fixing temperature. With
The apparatus is characterized in that heat is generated when a high frequency voltage is applied to the high frequency induction heating device from a high frequency power supply.

In order to solve the above-mentioned problems, the present invention comprises a heating rotator and a pressure rotator pressed against the heating rotator,
When the heating rotator reaches a predetermined fixing temperature, the transfer paper carrying the unfixed toner on the surface is passed through the nip portion of the rotator pair such that the toner carrying surface is in contact with the heating rotator. In a fixing device for performing fixing by heating, a high-frequency induction heating device including an induction heating coil to which a high-frequency voltage is applied by a high-frequency power supply, and a heating layer provided with the heating rotator and having a ferromagnetic powder dispersed therein are provided. The heat generating layer has a Curie point substantially set to the fixing temperature, and generates heat when a high frequency voltage is applied to the high frequency induction heating device from a high frequency power supply.

The present invention is effective when the Curie point of the ferromagnetic powder in the heat generating layer is approximately at the fixing temperature. Furthermore, in the present invention, the heating rotator has a base layer and a surface layer on the outermost peripheral surface, and the surface layer is formed of a release resin coating layer, and the base layer and the surface layer are formed by the heat generation. It is effective if adhered through the layers.

According to another aspect of the present invention, a high-frequency induction heating device including an induction heating coil to which a high-frequency voltage is applied by a high-frequency power source is heated to a predetermined fixing temperature. In a heating rotator employed in a fixing device for performing fixing by passing a transfer paper carrying unfixed toner on the surface thereof through a nip portion of the pair of rotators so that the toner carrying surface is in contact with the heating rotator, The Curie point of the magnetic heating layer provided on the heating rotator is substantially equal to the fixing temperature.

Further, in order to solve the above-mentioned problem, the present invention provides a high-frequency induction heating device comprising an induction heating coil to which a high-frequency voltage is applied by a high-frequency power supply, and the device is heated to a predetermined fixing temperature. In a heating rotator employed in a fixing device which performs fixing by passing a transfer sheet carrying unfixed toner on its surface through a nip portion of the pair of rotators so that the toner carrying surface is in contact with the heating rotator. ,
The heating rotator has a heating layer in which ferromagnetic powder is dispersed.

The present invention is effective when the Curie point of the ferromagnetic powder is approximately at the fixing temperature. Further, in the present invention, the heating rotator has a base layer and an outermost peripheral surface layer, the surface layer is formed of a release resin coating layer, and the heat generation layer is formed of the base layer and the surface layer. It is effective if it is made of an adhesive for bonding the two.

Further, in order to solve the above-mentioned problems, the present invention provides a method for manufacturing a heating rotator, wherein a step of forming an adhesive layer in which ferromagnetic powder is dispersed on a surface of a cylindrical cored bar, A step of applying a mold release resin powder to the electrostatic powder,
The method is characterized by having a step of baking in a heating furnace to bake the release resin layer, and a step of polishing the baked release resin layer surface in this order.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a heating roller 1 as a heating rotator of a fixing device according to the present invention. The heating roller 1 is configured by sequentially laminating an adhesive layer 3 in which ferromagnetic powder is dispersed and a release resin layer 4 on a cylindrical core 2. The core 2 is made of aluminum. The adhesive layer 3 is formed by dispersing ferromagnetic powder such as MnZn-based ferrite in an adhesive.

The release resin layer 4 is formed by baking on the adhesive layer 3. If a preferable example is specifically shown, a release resin powder containing a perfluoroalkoxy resin as a main component is applied onto the adhesive layer 3 by electrostatic powder coating. The baking is performed by firing in a heating furnace. The heating temperature for firing is around 360 ° C. In addition, the release resin layer 4
After baking, the surface is polished by a polishing means such as a grindstone or a buff. Note that the thickness of the release resin layer 4 is about 20 to 30 μm.

The heating roller 1 configured as described above is
The heat fixing device 5 is configured in combination with the pressure roller 6. Further, the fixing device is provided with a high-frequency induction heating device including an induction heating coil 7 to which a high-frequency voltage is applied by a high-frequency power supply 8, and the induction heating coil 7 is arranged close to and parallel to the heating roller 1. I have. Then, a high-frequency AC voltage is applied to the induction heating coil 7 from a high-frequency power supply 8.

The Curie point of the ferromagnetic powder dispersed in the adhesive layer 3 is about 180 ° C., and at this temperature, the ferromagnetic powder loses magnetism. Therefore, when an alternating current is applied to the induction heating coil 7 from the high-frequency power supply 8, in a state where the ferromagnetic powder has magnetism, a large current flows through the ferromagnetic powder and is heated to a high degree. However, since the ferromagnetic powder loses magnetism when it reaches the Curie point by heating, induction heating is not performed, and the surface of the heating roller 1 maintains a predetermined fixing temperature. If the temperature of the heating roller falls below the Curie point due to continuous paper passing, it is rapidly heated by induction heating, so that there is almost no decrease in temperature during continuous paper passing.

As a result of a paper passing test using the apparatus of the above embodiment, the surface of the heating roller 1 was found to have a fixing temperature of 180 ° C.
Was about 2 to 3 seconds, and the fluctuation in the surface temperature of the heating roller 1 during continuous paper passing was about ± 1 ° C.

[0018]

According to the above arrangement, the ferromagnetic material contained in the adhesive is instantaneously heated by the high frequency induction heating device until it reaches the Curie point, and loses magnetism when it reaches the Curie point. Keep the temperature constant without raising the temperature.
Since the Curie point of the ferromagnetic material is set substantially at the fixing temperature, the ferromagnetic material is generally maintained at the fixing temperature. Therefore, the rising time of the heating rotator can be shortened and high accuracy can be achieved without deteriorating the high releasability and heat resistance of the surface of the heating rotator required as a fixing device, and without requiring a complicated control device. Temperature control can be performed.

Heating bodies having different thicknesses and shapes of the core metal and the release resin layer have different heat capacities, but the rise time and the control can be controlled by adjusting the content of the ferromagnetic powder. Temperature accuracy can be improved.

Further, since the ferromagnetic powder loses magnetism at the Curie point, the toner containing the magnetic powder is attracted to the heating rotator by the magnetic force, and the offset does not occur.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a heating roller of a fixing device according to the present invention.

FIG. 2 is a perspective view illustrating a configuration of a fixing device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating roller 2 Core metal 3 Adhesive layer 4 Release resin coating part 5 Fixing device 6 Pressure roller 7 Induction heating coil 8 High frequency power supply

Claims (9)

(57) [Claims] 1. A transfer paper having a heating rotator and a pressure rotator in pressure contact with the heating rotator, the transfer paper carrying unfixed toner on the surface when the heating rotator reaches a predetermined fixing temperature, A fixing device that performs fixing by passing paper through a nip portion of the pair of rotating members so that a supporting surface is in contact with the heating rotating member; a high-frequency induction heating device including an induction heating coil to which a high-frequency voltage is applied by a high-frequency power source; A heating layer having magnetism provided on the heating rotator, wherein the heating layer has a Curie point substantially set to the fixing temperature, and a high-frequency voltage is applied to the high-frequency induction heating device by a high-frequency power supply. A fixing device that generates heat when heated. 2. A transfer paper, comprising a heating rotator and a pressure rotator pressed against the heating rotator, wherein a transfer paper carrying unfixed toner on a surface thereof is charged when the heating rotator reaches a predetermined fixing temperature. A fixing device that performs fixing by passing paper through a nip portion of the pair of rotating members so that a supporting surface is in contact with the heating rotating member; a high-frequency induction heating device including an induction heating coil to which a high-frequency voltage is applied by a high-frequency power source; A heating layer in which the ferromagnetic powder provided in the heating rotator is dispersed, and the heating layer has a Curie point substantially set to the fixing temperature, and a high-frequency power supply to the high-frequency induction heating device. A fixing device that generates heat when a high-frequency voltage is applied. 3. The fixing device according to claim 2, wherein the heat generating layer has a Curie point of the ferromagnetic powder substantially at the fixing temperature. 4. The heating rotator has a base layer and an outermost peripheral surface layer, wherein the surface layer is formed of a release resin coating layer, and the base layer and the surface layer are formed of the heat generating layer. 4. The fixing device according to claim 2, wherein the fixing device is adhered through the fixing device. 5. 5. A transfer sheet, which is heated to a predetermined fixing temperature by a high-frequency induction heating device comprising an induction heating coil to which a high-frequency voltage is applied by a high-frequency power supply, and in which the transfer paper carrying the unfixed toner on the surface is heated, A heating rotator employed in a fixing device that performs fixing by passing paper through a nip portion of the pair of rotators so that the toner carrying surface is in contact with the heating rotator, wherein a heat generated by magnetism provided on the heating rotator is provided. A heating rotator wherein the Curie point of the layer is approximately at the fixing temperature. 6. A transfer sheet carrying an unfixed toner on its surface heated to a predetermined fixing temperature by a high-frequency induction heating device comprising an induction heating coil to which a high-frequency voltage is applied by a high-frequency power supply. In a heating rotator employed in a fixing device for performing fixing by passing a paper through a nip portion of the pair of rotators so that the toner carrying surface is in contact with the heating rotator, the heating rotator has a ferromagnetic powder dispersed therein. A heating rotator comprising: a heating layer. 7. The heating rotator according to claim 6, wherein the Curie point of the ferromagnetic powder is approximately the fixing temperature. 8. The heating rotator has a base layer and an outermost peripheral surface layer, wherein the surface layer is formed of a release resin coating layer, and the heat generation layer is formed of the base layer and the surface layer. The heating rotator according to claim 6, wherein the heating rotator is configured by an adhesive for bonding the heating rotator. 9. The method of manufacturing a heating rotator according to claim 8, wherein the manufacturing method includes a step of forming an adhesive layer in which ferromagnetic powder is dispersed on the surface of the cylindrical cored bar, and a mold release thereon. Characterized in that it comprises, in this order, a step of applying an electrostatic powder to the conductive resin powder, a step of firing in a heating furnace to bake the release resin layer, and a step of polishing the baked release resin layer surface. Manufacturing method.