JPH0553457A - Heat fixing device - Google Patents

Abstract

PURPOSE:To provide a heat fixing unit concurrently improved with the nonstickiness and heat conductivity of the fluorinated carbon resin coated on a metal belt and simplified with the production process. CONSTITUTION:A heater 1 is provided at least on one of a pair of rollers 6, 11 pressed to each other and rotated, an image carrier 7 with an unfixed toner image is fed between the rollers 6, 11 to heat-melt and fix the unfixed toner image in a heat fixing device. The roller 11 with the heater 1 of the heat fixing device is constituted of an integrated structure type heating/cooling device 10 consisting of a cooling structural body 3 concurrently serving as a supporter and the heater 1, an endless metal belt 4 rotated in contact with the integrated structure type heating/cooling device 10 and dispersed with fluorinated graphite fine grains and surface-treated with dispersion nickel plating on the outer surface in contact with the image carrier 7, and a drive roller 5 rotatively driving the belt 4 while applying tension to the belt 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat fixing device for an image forming apparatus such as electrophotography.

[0002]

2. Description of the Related Art Several systems such as a hot plate system, a pressure system, and a heat roller system have been put into practical use as a heat fixing device indispensable for an electrophotographic recording apparatus. The heat roller system has been the mainstream for the past 10 to 20 years. Is. However, this method also has a drawback that it takes a long time to start the operation (temperature rising time to reach the fixing temperature) and consumes a large amount of power, which adversely affects the performance of the entire electrophotographic recording apparatus. is the current situation.

As a heat fixing device for drastically improving these, Canon Co., Ltd. has adopted a heat fixing device named SURF system in its products since February 1990.
This heat fixing device has successfully shortened the temperature rising time to about 5 seconds, and has succeeded in halving the power consumption. But,
This method also has a drawback that it has a short life and a large number of parts.

The present inventors have invented and applied for a patent for a system capable of fundamentally solving the problems of the SURF type fixing device while making full use of all the excellent features of this idea (Japanese Patent Application No. 2-293986). , Japanese Patent Application No. 2-339079, Japanese Patent Application No. 3-49392, “heat fixing device”).

The first feature of this type of heat fixing device is that an endless metal belt is used, whereby the heat generated by the heater can be effectively and quickly transferred to the unfixed toner on the recording paper. That is. This can significantly reduce the temperature of the heater and improve the thermal efficiency, and further reduce the power consumption.

This rapid and effective heat transfer enables rapid cooling after the toner is melted, and the offset phenomenon of the toner can be drastically improved by using a small integrated heating / cooling device. This is the second feature.

The third feature is that the heater of this heater has a PTC
The heater element can now be used. As is well known, the PTC heater element has a limited heating ability due to its low thermal conductivity, and there has been no practical application to a heat fixing device requiring a large heat generation amount. However, the low power consumption and rapid heat transfer of the fixing device proposed by the present inventors, and the structure capable of reducing the heat capacity around the PTC heater element to a very small level will provide conditions for utilizing this element, and the fixing speed 25 sheets (A4) / minute have been realized in a laboratory scale test. It can be said that this PTC heater has a thermometer and a control power source in the element itself, and these parts, which have been indispensable in the conventional heat fixing device, are completely unnecessary.

The fourth characteristic is that the adhesion to the fluororesin layer covering the surface of the endless metal belt can be easily brought to a level without problems. SUR described above
The reason why the life of the F-type fixing device is short is that the fluororesin coated on the surface of the endless belt made of polyimide resin peels off during use.

In addition to these features of the thermal fixing device of the present inventors, it becomes possible to fix to an envelope or the like, which has been impossible to prevent the generation of wrinkles, and has many excellent practical properties. It has features.

[0010]

By the way, the performance of the above-mentioned thermal fixing device developed by the present inventors is further improved,
It is an object of the present invention to reduce the manufacturing cost as well. It improves the non-adhesiveness and thermal conductivity of the fluororesin coated on the endless metal belt at the same time.
At the same time, the manufacturing process will be simplified. The improvement in non-adhesiveness brings offsetless toner, greatly expands the types of toner that can be applied, and enables standardization of heat fixing devices. The improved thermal conductivity contributes to safety by reducing the maximum temperature of the heater, and the improved thermal efficiency leads to a reduction in power consumption. Further, the PTC heater element can be used in a fixing device having a higher fixing speed. It is an object of the present invention to further improve the performance of a thermal fixing device of a type having excellent characteristics.

[0011]

The present invention adopts the following basic structure in order to achieve the above object. That is, in a heat fixing device for fixing a pair of rollers, each of which has a heating member on at least one of them and rotating in pressure contact with each other, and an image support having an unfixed toner image, between the rollers to melt and fix the unfixed toner image. A roller provided with the heat generating member, an integral structure type heating and cooling device comprising a cooling device which also functions as a support and a heat generating member, and an outer surface which comes into contact with the integral structure type heating and cooling device and rotates to contact an image support. A heat fixing device comprising: an endless metal belt having dispersed nickel plating surface treatment in which fine graphite fluoride particles are dispersed; and a driving roller for rotating the endless metal belt while applying tension to the endless metal belt.

Nickel metal may be used as the material of the endless metal belt. In that case, the endless metal belt comprises an electroforming bath of nickel metal belt and a plating bath of nickel fluoride dispersed graphite particles of the same system, and after forming the endless nickel metal belt on the mold, the endless nickel metal belt is formed. It can be manufactured by applying nickel fluoride graphite fine particle-dispersed nickel plating on it and releasing it from the mother die.

[0013]

[Function] It has been known as a recent research result that the dispersed nickel-plated surface in which fine graphite fluoride particles are dispersed has an astonishing water repellency ("Kagaku", Vol. 46, No. 7 (19).
91) 477). This contact angle shows 173 °, which is close to the limit, and is a value that is surprising even compared to 110 ° to 115 ° of fluororesin (PTFE) which is usually used as the one with the largest contact angle. is there. Moreover, since a large amount of fluorinated graphite fine particles are uniformly dispersed in the nickel metal base material having good thermal conductivity, the thermal conductivity and hardness are close to those of nickel metal.
Further, it has heat resistance of about 300 ° C., has sufficient abrasion resistance, and of course has good electrical conductivity.

That is, it has all the excellent characteristics as a non-adhesive surface coating layer of a heat roller for a heat fixing device.
In particular, it is the most effective coating material for the surface coating layer of the endless metal belt for the heat fixing device of the system developed by the present inventor. Moreover, since electroformed nickel is used as the optimal material for the endless metal belt, it is very easy to perform nickel plating treatment with graphite fluoride fine particles dispersed on the outer peripheral surface of this endless metal belt, and it has been conventionally used in terms of manufacturing cost. It is much cheaper than the fluororesin coating. This can be processed as part of the electroforming (plating) process, and since the same type of plating bath (for example, nickel sulfamate plating bath) can be used, dispersion plating can be performed immediately with electroformed nickel attached to the mother die. This is because it can be used as it is as it is if it is performed and then released from the mother die.

[0015]

【Example】

Embodiment 1 An embodiment of the present invention will be described below with reference to the accompanying drawings.
In addition, this embodiment is a patent application invention of the present inventors (Japanese Patent Application No.
No. 293986, Japanese Patent Application No. 2-339079, Japanese Patent Application No. 3-49392, “thermal fixing device”), and the thermal fixing device described in the embodiments of the above patent application inventions is used as it is. It can also be used as a heat fixing device in the embodiment of the present invention.

FIG. 1 is a sectional view of a heat fixing device of the present invention. The heat fixing device includes a heat roller 11 and a pressure roller 6. The heat roller 11 includes an integrated structure heating / cooling device 10, an endless metal belt 4 having an outer surface subjected to a non-adhesive surface treatment, and a drive roller 5 rotatingly driving the endless metal belt 4 in close contact with the integrated structure heating / cooling device 10. Has become. Pressure roller 6
Is pressed against the integral structure type heating / cooling device 10 with a force of several kg, but is driven to rotate by the rotational drive of the endless metal belt 4. While the recording paper 7 passes between the heat roller 11 and the pressure roller 6, the unfixed toner (not shown) on the recording paper is heated and melted by the heater 1 via the endless metal belt 4, and further the cooling structure. Three
It is cooled by and is released from the metal belt 4. At this time, the surface of the endless metal belt 4 must be non-adhesive so that the toner does not adhere to the surface. The heater 1 is most preferably a PTC heater, but may be a resistance heater, and in this case, only a thermometer and a control power supply for energization heating are required. The heater 1 is integrated with the cooling structure 3 via a heat insulating material 2.

Now, regarding the surface treatment method of the endless metal belt 4, first, a sectional view thereof is shown in FIG. The metal belt portion 8 can be manufactured by electroforming, and nickel, copper, or other alloys can be used as the material, but the object of the present invention is rigidity, elongation, corrosion resistance, and rotational drive life. Nickel is the best choice. As this electroforming bath, a sulfamic acid bath or a Watts bath is usually used.

On the other hand, as the dispersed nickel plating bath in which fine graphite fluoride particles are mixed and dispersed, a sulfamic acid bath or a Watts bath having the same plating bath composition and concentration is used, and a surfactant as a dispersant is slightly added. There is only a difference. Therefore, first, about 30μ on the cylindrical matrix.
m of nickel is electroformed and immediately put in a dispersion nickel plating bath to perform nickel plating 9 with a few micrometer thickness of fluorinated graphite fine particles dispersed on the nickel electroformed product, and after washing and drying, the plating surface is rapidly heated. When separated from the master mold and pulled out, the desired non-adhesive surface-treated endless nickel metal belt 4 is obtained. If the electroforming bath and the dispersion plating bath used here are unified to the same system of sulfamic acid bath or Watt bath, the composition and concentration of the dispersion plating bath will not change, which is a great advantage in terms of production technology. Needless to say.

[0019]

[Table 1]

That is, examples of the electroforming bath and the dispersion plating bath used here are shown in Table 1. The electroforming bath is very generally widely used, and the dispersion plating bath is available from Although it is manufactured by Uemura Kogyo, its main components are almost the same as those of the electroforming bath. Then, there is no particular problem even if the surfactant of the electroforming bath is mixed in the dispersion plating, and even if the electroformed product taken out from the electroforming bath is immediately placed in the dispersion plating bath and the dispersion plating is performed, no inconvenience occurs. . That is, electroforming and dispersion plating can be performed in almost the same process, and an endless metal belt having a non-adhesive surface can be manufactured in a very simple process. Although a high-concentration nickel sulfamate electroforming bath was actually used as the variable speed electroforming bath, there was basically no difference from the above case only because the nickel sulfamate concentration was high.

The dispersion plating thickness of 2 to 3 μm is sufficient, the change is so small that it can hardly be detected by the evaluation of the wear life, and since the nickel plating is the same, there is no problem such as peeling.

A thermal fixing device having the structure shown in FIG. 1 was produced using the endless metal belt 4 thus produced, and the thermal fixing device was mounted on a laser beam printer to carry out a fixing experiment. As a result, the temperature of the heater 1 can be reduced by about 20 ° C., and the power consumption can be reduced by about 20% or more, as compared with the heat fixing device having the same structure using a metal belt coated with 10 μm thick fluororesin (PTFE). Okay (heater temperature is 2
From 00 ℃ to 180 ℃, power consumption from 450W to 350
It became W. ). The surface wear of the endless metal belt 4 was within the measurement error even after the fixing experiment of 100,000 sheets, and no abnormality was found in the fixing performance or the offset.

Further, a toner having a similar fixing temperature is about 1
When the same fixing device of 0 type was evaluated, it was found that fixing was possible without any problems. The toner is used in the electrophotographic recording device shown in Table 2 and the like.

[0024]

[Table 2]

From the above results, it can be understood that the heat fixing device of the present embodiment has wide versatility, considering that almost one-to-one correspondence adjustment is indispensable in the conventional heat roller.

[0026]

As described above, it is desirable from the viewpoint of safety that the heater temperature is greatly reduced, and the improvement of the thermal efficiency realizes the significant reduction of power consumption. Further, the rationalization of the production method of the endless metal belt also brings about the cost reduction, which contributes to the cost reduction as a whole. Furthermore, the fact that the same fixing device can handle various toners has had a great effect on the standardization and rationalization of product design and manufacturing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a heat fixing device according to an embodiment of the present invention.

FIG. 2 is a sectional view of an endless metal belt according to an embodiment of the present invention.

[Explanation of symbols]

 1 Heater 2 Heat Insulating Material 3 Cooling Structure 4 Endless Metal Belt 5 Drive Roller 6 Pressure Roller 7 Recording Paper 10 Integrated Structure Heating / Cooling Device 11 Heat Roller

Claims (4)

[Claims] 1. A pair of rollers, at least one of which has a heat generating member and which rotate in pressure contact with each other, and an image support having an unfixed toner image, which is passed between the rollers to heat and fuse the unfixed toner image. In the fixing device, the roller provided with the heat generating member includes a cooling device also serving as a support, and an integral structure type heating and cooling device including a heat generating member,
An endless metal belt which is rotated in contact with the integral structure type heating and cooling device and has an outer surface in contact with the image support, on which a dispersed nickel plating surface treatment is performed in which fine graphite fluoride particles are dispersed, and while applying tension to the endless metal belt, A thermal fixing device comprising: a driving roller that rotationally drives an endless metal belt. 2. The heat fixing device according to claim 1, wherein the material of the endless metal belt is nickel metal. 3. A nickel metal belt electroforming bath and a graphite fluoride fine particle dispersed nickel plating bath are plating baths of the same system. After forming a nickel metal belt on a mother die, the nickel metal belt is fluorinated. The heat fixing device according to claim 2, wherein an endless metal belt manufactured by subjecting graphite fine particle-dispersed nickel plating to release from a mother die is used. 4. The nickel metal belt electroforming bath and the graphite fluoride fine particle dispersed nickel plating bath are plating baths of the same system, and after the nickel metal belt is formed on the mother die, the nickel metal belt is fluorinated. An endless metal belt for use in a heat fixing device of an image forming apparatus, which is manufactured by applying graphite fine particle-dispersed nickel plating and releasing it from a mother die.