JPH1140320A - Heating roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating roller that prevents a metal base composing a heating roller from being deformed and thereby, the position of the outer surface of the heating roller is never changed exceeding an allowable range while the heating roller is being rotated. SOLUTION: In a heating roller 10 that comprises a cylindrical metal base 11, a ceramic insulating film 12 formed on the outer surface of the metal base 11, a heating resistor 13 formed on the insulating film 12, and a mold-releasing layer 15 formed on the outermost surface of the heating roller 10 so as to cover the heating resistor 13, the metal base 10 contains not less than 4.2 wt.% of magnesium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heating roller,
More specifically, it is used as a heating roller for a heat roller type heat fixing device used for fixing a toner image in an electrophotographic copying machine, a laser printer, a facsimile, etc., a heating roller for a sheet body surface coating device, and a heater for various heating devices. It relates to a heating roller.

In an electrophotographic copying machine or the like, a method for heating and fixing a toner image formed on a recording material is as follows.
Conventionally, a heat roller for fixing an unfixed toner image to a recording material by passing a recording material on which an unfixed toner image is formed between a heating roller and a pressure roller disposed in contact with the heating roller. The scheme is widely known.

In recent years, as shown in JP-A-56-109381, JP-A-63-182684, and JP-A-6-186877, those in which the heating roller itself has a self-heating function have been adopted. . Such a conventional heating roller will be described with reference to the drawings.

FIG. 1 is an explanatory view of the structure of a conventional heating roller. The heating roller 100 has a cylindrical metal base 110.
And an insulating film 12 formed on the outer surface of the metal base 110, and a heating resistor 13 formed on the insulating film 12.
And a protective film 14 formed so as to cover the heating resistor 13, a release layer 15 formed on the protective film 14 and serving as the outermost surface of the heating roller 100,
And power supply rings 21 and 22 for supplying a current to the power supply ring. In addition, as shown in an exploded schematic view of the heating resistor in FIG. 3, 131 and 132 are termination electrodes provided at one end of the heating resistor.

[0005] The terminal electrode 13 of the heating resistor 13
In joining the power supply rings 21 and 22 with the power supply rings 21 and 22, the inner surfaces of the power supply rings 21 and 22 are directly contacted and fixed to the terminal electrodes 131 and 132 of the heating resistor 13 using shrink fitting technology.

[0006]

However, when the above-described heating roller 100 rotates around the rotation axis XX as shown in FIG. 1, the position of the outer surface of the heating roller 100 is larger than an allowable range. To change significantly.
Specifically, in FIG. 1, there is a problem that the position of the outer surface of the heating roller 100 fluctuates in a vertical direction on the paper surface, a direction perpendicular to the paper surface, or the like.

More specifically, the metal substrate 110 is a hollow cylindrical member, and is formed by drawing. At this time, the metal substrate 110 is an aluminum A5056-based material from the viewpoint that the thickness can be reduced, the drawing processability is improved, and the hardness is improved. On the other hand, the insulating film 12 formed on the outer surface of the metal base 110 is a ceramic film for ensuring insulation between the metal base 110 and the heating resistor 13. The composition is formed by firing the composition at about 180 ° C. A heating resistor 13 is fired on the insulating film 12 at about 400 ° C., and a release layer 15
Fired at 80 ° C.

That is, the firing temperature of the heating resistor 13 and the firing temperature of the release layer 15 are considerably higher than the firing temperature of the insulating film 12, and the firing resistor 13 and the release layer 15 are fired. Of the insulating film 1
2 contracted, and the metal base 110 made of aluminum was deformed by the contraction force. As a result, there is a problem that when the heating roller 100 is rotated, the position of the outer surface of the heating roller 100 greatly changes beyond an allowable range. The change in the position of the outer surface of the heating roller is indicated by the amount of change in the position of the outer surface of the heating roller. If the amount of change is 80 μm or less, it is recognized as an allowable range of the heating roller.

When such a heating roller 100 is used in an electrophotographic copying machine, the position of the outer surface of the heating roller 100 changes beyond an allowable range. There is a problem in that a portion that is weak in pressing the image is generated, and in the portion where the pressing is weak, the toner is not completely fixed and a fixing failure occurs.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent deformation of a metal base material constituting a heating roller, and therefore, to prevent heating when a heating roller rotates. An object of the present invention is to provide a heating roller in which the position of the outer surface of the roller does not change beyond an allowable range.

[0011]

According to a first aspect of the present invention, there is provided a heating roller comprising: a cylindrical metal base; and a ceramic insulating member formed on an outer surface of the metal base. A heating roller comprising: a film, a heating resistor formed on the insulating film, and a release layer formed on the outermost surface of the heating roller so as to cover the heating resistor. The metal base material is characterized by containing 4.2% by weight or more of magnesium.

[0012]

FIG. 1 shows a heating roller 10 according to the present invention.
2 is a partially broken front view showing the configuration of FIG.
It is arrow sectional drawing. As shown in FIGS. 1 and 2, the heating roller 10 of the present invention is an aluminum A5056-based aluminum alloy containing 4.33 magnesium from the viewpoints of reducing the thickness and improving the drawability and improving the hardness. 20% outside diameter including wall thickness, 0.8mm wall thickness,
A hollow cylindrical metal substrate 11 having a total length of 304 mm, and a 100 μm-thick ceramic film formed on the outer surface of the metal substrate 11 to ensure insulation between the metal substrate 11 and the heating resistor 13. An insulating film 12; a heating resistor 13 containing silver-palladium as a 15 μm-thick conductor formed on the insulation film 12; and a 100 μm-thick ceramic formed to cover the heating resistor 13 And a heating film 10 formed on the protection film 14.
A release layer 15 made of a fluororesin and serving as an outermost surface and having a thickness of 20 μm, and power supply rings 21 and 22 for passing a current through the heating resistor 13.

Although the protective film 14 is used in the present embodiment, the heating resistor 13 may be directly covered with the release layer 15 without using the protective film 14. In this case, the release layer 15
Must be highly insulating.

Then, as in the prior art, the metal substrate 11
The coating composition for forming an insulating film is baked at 180 ° C. on the upper outer surface to form an insulating film 12, a heating resistor 13 is baked on the insulating film 12 at about 400 ° C. The release layer 15 is fired at about 380 ° C. on the outer surface.

However, since the metal base material 11 constituting the heating roller of the present invention contains 4.2% by weight or more of magnesium, the drawability is slightly inferior to that of conventional aluminum, but the hardness is increased. And insulating film 12 by two high-temperature firing steps of firing release layer 15
Resistance to shrinkage of the metal substrate 1
1 can be prevented. Therefore, when the heating roller rotates, the change in the position of the outer surface of the heating roller is
The change amount is 80 μm or less, and the change does not exceed the allowable range.

<Experimental Example> An experiment was conducted to examine the change in the position of the outer surface of the heating roller using a heating roller similar to the heating roller shown in FIG. 1 except that the amount of magnesium in the metal substrate was changed. Was. The change in the position of the outer surface of the heating roller is indicated by the amount of change in the position of the outer surface of the heating roller. FIG. 4 shows the results.

As shown in FIG. 4, when the content of magnesium in the metal substrate is 4.2% by weight or less, the change amount is 80%.
μm or more, indicating that the change in the position of the outer surface of the heating roller exceeds the allowable range. This is due to the effect of the two high-temperature firing steps for firing the heating resistor and the release layer.
This is because the metal base is deformed by the contraction force of the insulating film.

On the other hand, when the content of magnesium in the metal base is 4.2% by weight or more, the change amount becomes 80 μm or less, and it can be seen that the change in the position of the outer surface of the heating roller is within an allowable range. This is because the metal substrate does not deform due to the increased hardness of the insulating film due to the contraction force of the insulating film due to the two high-temperature firing steps of firing the heating resistor and the release layer.

Next, when the toner is fixed using a heating roller having a metal content of 4.2% by weight or less in an electronic copying machine, the position of the outer surface of the heating roller is more than an allowable range. As a result, a portion was generated that was weak in pressing against the unfixed toner image passing between the heating roller and the pressure roller, and this portion became defective in fixing. In addition, when the toner was fixed using a heating roller in which the content of magnesium in the metal base material was 4.2% by weight or more in an electronic copying machine, fixing failure did not occur.

[0020]

According to the heating roller of the present invention, since the metal base constituting the heating roller contains 4.2% by weight or more of magnesium, the deformation of the metal base is prevented.
When the heating roller rotates, the heating roller does not change the position of the outer surface of the heating roller beyond an allowable range.

[Brief description of the drawings]

FIG. 1 is a partially broken front view showing a heating roller of the present invention and a conventional heating roller.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is an exploded schematic view of a heating resistor used in the heating roller of the present invention and a conventional heating roller.

FIG. 4 is a graph showing the results of an experimental example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Heating roller 11 Metal base material 12 Insulating film 13 Heating resistor 14 Protective film 15 Release layer 21 Power supply ring 22 Power supply ring

Claims (1)

[Claims] 1. A cylindrical metal base, a ceramic insulating film formed on an outer surface of the metal base, a heating resistor formed on the insulating film, and covering the heating resistor. And a release layer formed on the outermost surface of the heating roller, wherein the metal base contains 4.2% by weight or more of magnesium. roller.