JPS63192069A - Heater roll for fixing - Google Patents

Abstract

PURPOSE:To prevent the rise of surface temperature of a paper non-passing part at the time of continuously copying small-sized paper and to prevent the reduction of the surface temperature of a paper passing part at the time of continuously copying small-sized thick paper like postal card by increasing the electric resistance of a heat generating film in a small-sized paper passing range. CONSTITUTION:A heat generating film 3 consisting of a nickel-chromium alloy thin film is provided on the surface of a roll base material 2 consisting of insulating materials like ceramics or a heat-resistant resin, and a 'Teflon(R)'-coated releasable layer 4, electrodes 5, and bearings 6 are provided on the outside surface of this film 3; and when a voltage is applied to the heat generating film 3 through electrodes 5, Joule's heat is generated. The surface roughness of the roll base material 2 in a part (a) corresponding to the position of a postal card is set to 5mum and that of a part (b) is set to <=1mum, and the resistance heat generating film 3 is formed on the surface. Thus, the rise of surface temperature of the paper non-passing part is suppressed at the time of continuously copying small-sized paper, and the reduction of surface temperature of the paper passing part is prevented at the time of continuously copying small-sized thick paper like postal card.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat generating roll for fusing in a copying machine, and in particular relates to its surface temperature control. generally has a substantially uniform surface temperature distribution in the longitudinal direction.

However, when the heating element roll described above is used in a copying machine or printer that operates on one side of paper passing, continuous copying of small-sized paper causes an increase in the surface temperature of the non-paper passing area, causing the release layer and fixing roller to rise. Conventionally, the first method to solve this problem was to connect multiple resistor heating patterns with self-temperature control in parallel to the power supply to accommodate the paper size. (% Japanese Patent Publication No. 58-194074), or as a second method, a method in which the power supply range to the heating element is changed according to the inside of the paper (C% Japanese Patent Publication No. 58-221875) is known. .

Problems to be Solved by the Invention In the first method, a resistance heating element pattern is formed on the roller, which complicates the roller configuration and leads to an increase in cost.

In the second method, when small-sized base paper such as postcards is continuously copied, the amount of heat absorbed by the paper during fixing is too great, and the power supply cannot keep up, causing a drop in the surface temperature of the paper passing section, resulting in defective fixing.

In addition, when large-size paper is copied after continuous copying of small-size paper, the surface temperature decreases due to no voltage being applied to the paper feeding section during continuous small-size paper feeding, resulting in poor fixing. Therefore, the present invention The purpose is to suppress the rise in surface temperature of the non-paper passing section during continuous copying of small-sized paper, and to prevent the surface temperature drop of the paper passing section during continuous copying of small-sized thick paper such as postcards with a simple configuration. shall be.

In order to achieve an object that is more than a means for solving the problems, the present invention provides a fixing heat generating roll that forms a resistance heat generating film on the roll outer skin, in which the electrical resistance of the small size paper passing range is larger than that of other parts. It is characterized by the formation of a heat-generating film.

The heat source of the heat-generating roll for fixing uses Joule heat from the heat-generating film. This heat source is (resistance) x (current) 2, so if the resistance in the small paper passing section is made much higher than in the non-paper passing section, the amount of heat supplied to the paper passing section can be transferred to the non-paper passing section. Therefore, when making continuous copies of small-sized paper, the amount of heat supplied to the non-paper passing area is smaller than that of the paper passing area, so the temperature rise in the non-paper passing area can be kept to a small level. .

Furthermore, when small-sized thick paper such as postcards is continuously copied, the amount of heat supplied to the paper passing section is reduced, so the temperature drop is small and fixing failure does not occur. Note that the non-sheet passing section is supplied with an amount of heat that does not cause fixing failure when dog-sized paper is passed through. The fixing strength becomes saturated when it exceeds a certain value, so
The fixing strength does not slope as much as the heat supply amount slopes.

Example , Hereinafter, the present invention will be explained based on examples.

In FIG. 1, the heat generating roll for fixing (1) has a roll base material (2) made of an insulating material such as ceramic or heat-resistant resin and has a surface shape shown in FIG. ), a heat-generating film (3) formed by sputtering a 0.3 μm thick nickel-chromium alloy thin film on the surface of the electrode ( 5) and a bearing (6). When a voltage is applied to the heat generating film O) via the electrode (5), Joule heat is generated.

FIG. 2 is a partially enlarged view of FIG. 1. At the position of the postcard shown in Figure 3, the surface roughness of the roll base material in the corresponding part a is set to R.
a = 5 μm, the surface roughness of part b is Ra = 1 μm or less,
A resistance heating film with a thickness of 0.3 μm is formed on its surface. After forming the releasable layer (4), polish the surface! , so
The surface roughness is uniform regardless of the surface shape of the roll base material (23).

FIG. 4 shows surface temperature changes in portions a and b when 100 postcards are continuously copied using the heating roller for fixing having the structure shown in FIGS. 1 and 2. FIG. As shown in this figure, the surface temperature of part b of Saturn is Teflon (releasing layer (4)).
It is kept within a range that does not adversely affect the life of the fixing separation claw (not shown).

Further, the decrease in surface temperature of the third copy was small, and the fixing strength of the postcard was sufficient.

Figure 5 shows that the surface roughness of the roll base material for both parts 3 and b is Ra=
This figure shows the surface temperature changes in parts a and b when 100 postcards are continuously copied using a heat generating roll for fixing having a diameter of 1 μm. In this configuration, part b is made of Teflon (releasing layer (4)).
), the surface temperature rose to around 260° C., which is the use limit temperature (heat-resistant temperature) of the device, and there was a risk that the life of the heating roller and fixing roller separating claw would be shortened. In addition, in part a, the surface temperature decreased significantly, and the fixing strength of some postcards was poor.

In addition to the above-mentioned method, there is a method of increasing the resistance by reducing the thickness of the heat-generating film, as disclosed in JP-A-59-102267, JP-A-59-102268.
The object of the present invention can also be achieved in the heating element roll for fixing constructed by the method of increasing the thickness of the roll base material to reduce the thickness of the heating film and thereby increasing the resistance. This is because the same can be achieved.

Effects of the Invention According to the present invention, as described above, the surface temperature of the non-paper-passing area during continuous copying of small-size paper can be reduced by a simple method of increasing the electric resistance in the small-size paper passing range of the heating element roll for fixing. We were able to effectively solve the problem of temperature rise and temporary drop in surface temperature of the paper passing section during continuous copying of small size cardboard such as postcards.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a heat generating roll for fixing according to the present invention, FIG. 2 is a partially enlarged view of FIG. 1, and FIG. 3 is a diagram corresponding to the paper passing range of the roll. Figure 4 shows the temperature change when 100 postcards were continuously copied for the embodiment of the present invention.
The figure shows similar experimental results using a conventional example. (1)... Heating roll for fixing C)... Roll base material C)... Heat generating film (4)... Release layer (5)... Electrode (6)...
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Claims (1)

[Scope of Claims] 1. A heat generating roll for fixing in which a resistance heat generating film is formed on the outer skin of the roll, characterized in that the heat generating film is formed such that the electric resistance in the small size paper passing range is larger than in other parts. A heating element roll for fixing. 2. As a means of electrical resistance control, the surface roughness of the roll base material on which the heat generating film is formed is made large in the small size paper passing range and small in other parts. Heat generating roll for fixing.