JP2001023767A - Heat roller device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce heat capacity and quicken temperature rise time by installing a magnetic metal pipe or a magnetic metal film being induction-heated with a magnetic flux generating from a heating coil formed by wining on ferrite set to specified Curie temperature by adjusting composition. SOLUTION: Curie temperature of ferrite 9 on which a heating coil is wound, arranged inside a heating roller 8 in a induction heating part for heating a magnetic metal pipe 7 is set at about 200 deg.C slightly higher than the melting temperature of toner in a fixing device of a copying machine. Supply current from a high frequency power source 11 to a heating coil 10 in which magnetic resistance of the ferrite 9 which becomes nonmagnetic by increase in temperature to a higher value than Curie temperature is increased, and inductance is decreased is limited to the specified amount same as a magnetic state, and thereby, a magnetic flux for interlinking the magnetic metal pipe 7 is decreased. Self-temperature control capability caused by reduction of heating values according to decrease in induction current is developed. Even if temperature in a paperless part is increased to Curie temperature or higher, temperature is corrected to eliminate uneven temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat roller device used in a heat fixing device for toner such as a copying machine or a laser beam printer, or a laminating device for a steel plate.

[0002]

2. Description of the Related Art Most fixing units of copying machines such as copiers and laser beam printers are usually constructed as shown in FIG. A sheet 1 such as paper transfers toner powder 2 by static electricity or the like, and passes between a heat roller 3 and a pressure roller 4 heated to a high temperature. As a result, the toner powder 2 transferred onto the sheet 1 is heated and melted, and is pressed and fixed on the sheet 1. As a heating source of the heat roller 3, a heat roller 3
The halogen lamp heater 5 arranged in the center of the above is used. Further, the surface temperature of the heat roller 3 is detected by a thermistor sensor 6 arranged in contact with the surface of the heat roller 3, and the output of the halogen lamp heater 5 is controlled so that this temperature becomes a predetermined temperature. Is what it is.

[0003]

A conventionally known heat roller device represented by the above-mentioned copying apparatus has a problem that it is very difficult to control the temperature of the heat roller. That is, for the convenience of the user, the copying apparatus is adapted to various sizes of paper. For example, the heat roller to be used is one capable of supporting A3 size paper, and is capable of copying a size from A5 size paper to A3 size paper. At this time, A5
When copying the size paper, if the temperature of the portion through which the paper passes is made constant, the temperature of the heat roller will rise excessively because the heat is not taken by the paper in the portion through which the paper does not pass. Therefore, in order to make the temperature of the heat roller uniform, it is necessary to manufacture the heat roller from aluminum or the like having good heat conductivity, and to increase the thickness of the plate in order to improve heat conduction. Therefore, there is a problem that the heat capacity of the heat roller becomes large and it takes time for the temperature to rise. Then, this invention aims at providing the heat roller apparatus which solved the above-mentioned conventional problem.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional structure, and uses a heating coil wound around a ferrite having a predetermined Curie temperature by adjusting the composition. The heat roller device directly heats a magnetic metal pipe or a magnetic metal film by induction heating.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention described in claim 1 is a heating coil wound on a ferrite having a predetermined Curie temperature by adjusting the composition, and a magnetic induction heating by a magnetic flux generated from the heating coil. A metal pipe or a magnetic metal film is provided, and when the ferrite rises above the Curie temperature by heat conduction and becomes non-magnetic by induction heating the magnetic metal pipe or the magnetic metal film, the magnetic resistance of the ferrite increases and the heating coil Since the inductance is small, if the current supplied to the heating coil is limited to the same amount as that for magnetism, the magnetic flux linking the magnetic metal pipe or magnetic metal film to be heated decreases, the induced current decreases, and the heat generation decreases. With self-temperature controllability, this configuration can be used with a toner fixing device, a steel plate or plastic. Heat b by performing the heat roller apparatus for use in laminating device or the like - to reduce the heat capacity of the color device, it is possible to rise time of temperature as fast heat roller device.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a perspective view of a main part of a heat roller device according to the present invention. A first embodiment will be described with reference to FIG. The heat roller device of the present embodiment is used for a fixing device of a copying machine. The composition of the material of the ferrite 9 is adjusted so that the Curie temperature is about 200 ° C., which is a suitable temperature, that is, a temperature slightly higher than the temperature at which the toner is melted. When the composition is used for another purpose, the composition is changed so that the Curie temperature according to the purpose is obtained.

[0008] The magnetic metal pipe 7 is heated by an induction heating unit for inductively heating the magnetic metal pipe 7. The induction heating unit is composed of a heating coil 10 wound around a ferrite 9 disposed inside a pressure roller 8 made of silicon rubber or the like, and a high frequency power supply 11 for supplying a predetermined amount of high frequency current to the heating coil 10. ing.

The operation of this embodiment will be described below. When a switch (not shown) is operated, the high-frequency power supply 11 starts operating and supplies a high-frequency current to the induction heating coil 10. A high-frequency magnetic field corresponding to the supplied high-frequency current is generated from the induction heating coil 10. The high-frequency magnetic field penetrates through the pressure roller 8 and interlinks with the magnetic metal pipe 7 to heat the magnetic metal pipe 7 by induction. Since the composition of the ferrite 9 is adjusted so as to have a Curie temperature at an appropriate temperature, when the ferrite rises above the Curie temperature due to heat conduction and becomes non-magnetic, the magnetic resistance increases and the inductance of the heating coil 10 decreases. Therefore, if the current supplied from the high-frequency power supply 11 to the heating coil 10 is limited to the same predetermined amount as in the case of magnetism, the magnetic flux interlinking the magnetic metal pipe 7 to be heated is reduced, the induced current is reduced, and the calorific value is significantly reduced. Therefore, the temperature of the magnetic metal pipe 7 decreases and the temperature of the ferrite also decreases. In this manner, self-temperature controllability in which the temperature is stabilized near the Curie temperature is provided. Further, if the temperature of the portion without paper is higher than the Curie temperature with or without paper, the temperature of the magnetic metal pipe 7 decreases as described above. Even if the temperature is partially non-uniform, it works to compensate for it.

[0010]

According to the first aspect of the present invention, there is provided a heating coil wound on a ferrite having a predetermined Curie temperature by adjusting the composition, and a magnetic metal pipe which is induction-heated by a magnetic flux generated from the heating coil. Alternatively, by employing a configuration including a magnetic metal film, the heat capacity can be reduced and the rise time of the temperature can be shortened.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a heat roller device according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a main part of a conventional heat roller device.

[Explanation of symbols]

 7 Magnetic metal pipe 8 Pressure roller 9 Ferrite 10 Heating coil 11 High frequency power supply

Claims (1)

[Claims] 1. A heating roller provided with a heating coil wound around a ferrite whose composition is adjusted to a predetermined Curie temperature, and a magnetic metal pipe or a magnetic metal film which is induction-heated by a magnetic flux generated from the heating coil. apparatus.