JPH10221982A - Image fixing device - Google Patents

Abstract

(57) [Problem] To enable a small amount of oil to be applied even in a fixing device using a toner based on a polyester resin having a low wax content, which is sufficient even when a printing speed is high. It is an object of the present invention to provide an image fixing device that can achieve a high fixing performance and can be downsized. SOLUTION: In an image fixing device provided with a plurality of rollers, an endless belt stretched over these rollers, and a heating means for heating the endless belt, a heating device arranged at a leading end of a conveying path of a recording sheet 3 is provided. A guide roller 17 is in contact with the roller 11 via the endless fixing belt 14, and a pressure roller 16 is in contact with the driving roller 13 disposed at the rear end of the recording paper 3 in the conveyance path and the fixing belt 14. A paper pressing roller 18 is provided in a heating and conveying path between the guide roller 17 and the pressure roller 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image fixing device, and more particularly, to an image fixing device in which an electrostatic latent image formed on a photoreceptor is visualized by toner particles and transferred to a recording sheet by heat and pressure. And an image fixing device for fixing the image to recording paper.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic copying machine has used an electrophotographic fixing device for fusing and fixing toner on a recording medium by fusing and pressing. Hereinafter, the conventional image fixing device and toner will be described.

Generally, a toner based on a polyester-based resin or a styrene-acryl-based resin used in a black-and-white copying machine contains a release material such as wax in an amount of about 4 to 6% by weight of the toner. Since this wax component exudes between the fixing roller and the toner at the time of fixing and can function as a release oil, the fixing device is an oilless type that does not directly apply a release material to the heating roller or a small amount of a fixing device. Is becoming mainstream.

On the other hand, in the case of a color copying machine, it is necessary to sufficiently melt the toner in order to emphasize the color reproducibility of the fixed image, the glossiness of the image, the transparency of OHP, and the like. As a result, the quality of the image deteriorates, so that the release material cannot be added much to the toner itself. Generally, the amount of the release material added is 2% or less in terms of toner weight ratio. Therefore, with only the release material added to the toner, a high-temperature offset in which the melted toner adheres to the surface of the heating roller easily occurs. In order to prevent this, in a fixing device of a conventional color copying machine, a large amount of silicone oil as a release material is applied to the roller surface.

Here, a configuration of a conventional color copying machine provided with such an oil application mechanism will be described. FIG. 3 is a main part configuration diagram of a conventional image fixing device.

Reference numeral 1 denotes a heating roller, 2 denotes a pressure roller, and 3 denotes a recording sheet. Reference numeral 4 denotes an oil tank in which silicone oil 5 is stored. Reference numeral 6 denotes a pump utilizing the reciprocating motion of a piston. The pump 6 pumps up the oil 5 in the oil tank 4 and drops it on the oil supply felt 7 in conjunction with the rotation of the heating roller 1. The oil supply felt 7 diffuses the oil in the longitudinal direction, and supplies the oil 5 uniformly over the entire length of the oil application roller 8. Reference numeral 9 denotes an oil regulating blade made of fluoro rubber, which removes excess oil 5 on the surface of the heating roller 1 to form a uniform oil thin layer. The removed oil 5 is collected in the oil tank 4 through the oil receiver 10. The oil 5 on the heating roller 1 is thinned by an oil regulating blade 9 to form a toner release layer, thereby preventing occurrence of offset of the molten toner to the heating roller 1.

[0007]

In order to apply silicone oil as a release material to the heating roller in order to prevent offset as described above, a release oil application mechanism as described with reference to FIG. 3 is provided. Therefore, various problems such as an increase in the size of the device, an increase in cost, and a complicated maintenance occur. In addition, since silicone oil adheres to the transfer material after fixing, and in particular, silicone oil does not permeate the OHP sheet, there is a problem that the user easily stains his / her hands with silicon oil remaining on the sheet surface.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and enables a small amount of oil to be applied to a fixing device using a toner based on a polyester resin having a low wax content. It is another object of the present invention to provide an image fixing device that can achieve sufficient fixing performance even when the printing speed is high and can be downsized.

[0009]

Means for Solving the Problems To achieve this object, the inventors of the present invention have conducted intensive studies, and as a result, by enabling stable fixing at a lower temperature than in the past, the present inventors have made it possible to achieve a high temperature with less release material than in the past. The inventors have found that the offset can be prevented, and have completed the present invention.

That is, the present invention comprises a plurality of rollers, an endless belt stretched over these rollers, and a heating means for heating the endless belt. Using an image fixing device that conveys and fuses the toner while making contact with the outer peripheral surface of the endless belt, the recording medium comes into contact with one of a plurality of rollers disposed at the leading end of the conveyance path of the recording medium via the endless belt. A guide roller, and a pressure roller that comes into contact with one of a plurality of rollers disposed at the rear end of the recording medium conveyance path via an endless belt, and heats up between the guide roller and the pressure roller. By providing a paper pressing means in the transport path and using a roller as the shape, the transportability of the recording medium is ensured, and stable fixing performance is ensured. In addition, by using a cleaning roller as a means for applying tension to the endless belt, the number of components can be reduced, and the cost and the size of the apparatus can be reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises a plurality of rollers, an endless belt stretched over these rollers, and a heating means for heating the endless belt, and a recording medium. An image fixing device that conveys and fuses the toner while bringing the unfixed toner image surface carried on the endless belt outer peripheral surface into contact with the outer peripheral surface of the endless belt. A guide roller that comes into contact with one of the rollers via an endless belt, and a pressure roller that comes into contact with one of a plurality of rollers disposed at the rear end of the recording medium conveyance path via the endless belt; Providing the paper pressing means in the heating conveyance path between the roller and the pressure roller has the effect of stabilizing the conveyance of the recording medium and ensuring stable fixing performance.

According to a second aspect of the present invention, in the first aspect of the invention, by using a roller as the paper pressing means, the transportability of the recording medium is improved, and the endless belt and the recording medium are transported. This has the effect of improving adhesion and improving fixing performance.

According to a third aspect of the present invention, there are provided a plurality of rollers, an endless belt wrapped around these rollers, and a heating means for heating the endless belt. An image fixing apparatus which conveys and fuses the toner while bringing the unfixed toner image surface into contact with the outer peripheral surface of the endless belt, wherein the belt fixing means is brought into contact with the outer peripheral surface of the endless belt to form an endless belt. It has the effect of increasing the adhesion between the belt and the recording medium and improving the fixing performance.

According to a fourth aspect of the present invention, in the third aspect of the invention, the number of parts can be reduced by using a cleaning roller for cleaning the belt surface as the belt stretching means. This has the effect of enabling cost reduction and downsizing of the device.

Hereinafter, embodiments of the present invention will be described. (Embodiment 1) FIG. 1 is a configuration diagram of a main part of an image fixing device according to a first embodiment of the present invention.

In FIG. 1, reference numeral 11 denotes a heating roller,
The heater 12 is contained in a metal tube having high thermal conductivity such as aluminum. Reference numeral 13 denotes a drive roller having an elastic layer of silicone rubber or the like on the outer periphery of a metal roller, and the drive is transmitted from a drive source (not shown) via a transmission mechanism. 14
Is a fixing belt having good thermal conductivity, and the base is an endless belt made of nickel having good thermal conductivity or polyimide having excellent heat resistance. As a result, the heat of the heating roller 11 is transmitted to the recording paper 3 via the fixing belt 14 and the recording paper 3
The upper toner can be fixed on the recording paper 3.
On the outer periphery of the base of the fixing belt 14, a silicone rubber coating layer having releasability and elasticity is formed. As a result, the releasability of the recording paper 3 and the fixing belt 14 at the time of heat fixing is improved, and it is possible to reduce peeling failure at the time of paper discharge. As a coat layer having such a function, a Teflon-based or fluorine-based coat layer is also conceivable.

The fixing belt 14 is hung around the heating roller 11 and the driving roller 13, and
The tension is given by 5. Reference numeral 16 denotes a pressure roller, which is provided on the outer periphery of the metal roller with a fluorine-based resin coat for reducing a friction coefficient with the recording paper 3. Reference numeral 17 denotes a guide roller for guiding the recording sheet 3 from a second transfer section (not shown) to the fixing section, and guides the recording sheet 3 to the start of the linear portion of the fixing belt 14. Reference numeral 18 denotes a paper pressing roller serving as a paper pressing unit, which brings the recording paper 3 into close contact with the fixing belt 14 in a heating conveyance path.

Reference numeral 19 denotes a belt tension spring attached to the tension roller 15, which applies an appropriate tension to the fixing belt 14 applied to the heating roller 11 and the driving roller 13 to prevent unnecessary loosening and the like. It plays the role of improving the adhesion between the recording paper and the recording paper. Reference numeral 20 denotes a pressing roller 16 which drives the driving roller 1 via the fixing belt 14.
3 is a pressure spring. The toner melted by the pressure is caused to enter the fibers of the recording paper 3. Reference numeral 21 denotes a guide roller pressing spring, which brings the recording paper 3 into close contact with the belt in a heating conveyance path. A paper pressing spring 22 supports the paper pressing roller 18 and presses the recording paper 3 against the fixing belt 14 via the paper pressing roller 18.

The operation of the thus configured image fixing device will be described below. The recording paper 3 on which the toner image is placed is guided by the guide roller 17 to the vicinity of the start of the straight portion of the fixing belt 14, and the unfixed toner image contacts the outer peripheral surface of the fixing belt 14. Fixing belt 14 and recording paper 3
Moves at the same linear velocity, and the unfixed toner image is pressed against the fixing belt 14 by the paper pressing roller 18 and is conveyed to the pressurizing unit without any deviation. The recording paper 3 conveyed to the pressurizing unit is conveyed while being pressed between the drive roller 13 and the pressurizing roller 16 via the fixing belt 14, and is sent to a paper discharge unit (not shown).

Tables 1 and 2 below show the results of comparison between the fixing device of the present invention and the conventional fixing device in terms of structure and fixing property.

[0021]

[Table 1]

[0022]

[Table 2]

As is clear from Table 2, the fixing device according to the present invention fixes even at 150 ° C., and it is possible to perform fixing at a temperature considerably lower than the fixing temperature of 170 ° C. in the conventional fixing device. . This is because the use of the belt increases the heating distance and gives a sufficient amount of heat for fixing.

Next, the occurrence of offset due to the difference in the amount of oil applied between the present invention and the conventional method was compared. The toner composition, recording paper and oil used here are as shown in Table 3.

[0025]

[Table 3]

The fixing temperature of each unit is shown in Table 2.
And the fixing temperature of the fixing device of the present invention is 150 ° C., and the fixing temperature of the conventional method is 170 ° C.
And

The relationship between the amount of applied oil and the occurrence of offset is shown in Table 4.

[0028]

[Table 4]

As is clear from Table 4, according to the present invention, the use of the belt increases the heating distance, and thus the fixing temperature can be set low. It can be seen that even when the amount of oil applied per sheet is reduced to 2 to 3 mg, good fixing performance without offset is exhibited.

(Embodiment 2) FIG. 2 is a structural view of an essential part of an image fixing apparatus according to a second embodiment of the present invention. Note that the configuration of the driving rollers and the like is the same as that of the first embodiment, and thus the description thereof will be omitted.

In this embodiment, the tension roller 23
Is provided with a cleaning layer 24 such as a felt material. In this manner, by providing the tension roller used for stretching the belt with a function of cleaning the surface of the belt, it is not necessary to separately provide a cleaning member. As a result, the cost can be reduced by reducing the number of parts, and the space for mounting the cleaning member is not required, so that the space can be reduced.

[0032]

As described above, the present invention comprises a plurality of rollers, an endless belt wound around these rollers, and a heating means for heating the endless belt. Using an image fixing device that conveys and fuses the toner while bringing the toner image surface into contact with the outer peripheral surface of the endless belt, one of a plurality of rollers disposed at the leading end of the recording medium conveying path and the endless belt are used. A guide roller, which is in contact with the recording medium, and a pressure roller which is in contact with one of a plurality of rollers disposed at the rear end of the recording medium conveyance path via an endless belt. By providing a paper pressing means in the heating and conveying path between the rollers and using a roller as its shape, it is possible to ensure the recording medium conveyance properties and to ensure stable fixing performance at low temperatures, thereby reducing the amount of release material. High in quantity It is possible to obtain an image fixing apparatus having no offset.

Further, by employing a cleaning roller for cleaning the surface of the endless belt as a means for stretching the endless belt, the number of parts can be reduced, and the cost and the size of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an image fixing device according to a first embodiment of the present invention.

FIG. 2 is a main part configuration diagram of an image fixing device according to a second embodiment of the present invention;

FIG. 3 is a configuration diagram of a main part of a conventional image fixing device.

[Explanation of symbols]

 3 Recording Paper 11 Heating Roller 12 Heater 13 Drive Roller 14 Fixing Belt 15 Tension Roller 16 Pressure Roller 17 Guide Roller 18 Paper Press Roller 19 Belt Tension Spring 23 Tension Roller 24 Cleaning Layer

Claims (4)

[Claims] An endless belt wrapped around these rollers; and a heating means for heating the endless belt, wherein an unfixed toner image surface carried on a recording medium is transferred to the endless belt. An image fixing device that conveys and fuses toner while being in contact with an outer peripheral surface, wherein the guide is in contact with one of the plurality of rollers disposed at a leading end of a conveyance path of the recording medium via the endless belt. A roller, and a pressure roller that contacts one of the plurality of rollers disposed at the rear end of the recording medium conveyance path via the endless belt, and the guide roller, the pressure roller, An image fixing device, wherein a paper pressing means is brought into contact with the outer peripheral surface of the endless belt in the heating and conveying path during the fixing. 2. An image fixing apparatus according to claim 1, wherein said paper pressing means is a roller. 3. An endless belt provided with a plurality of rollers, an endless belt stretched over these rollers, and a heating means for heating the endless belt, wherein an unfixed toner image surface carried on a recording medium is transferred to the endless belt. What is claimed is: 1. An image fixing device for conveying and fusing toner while being in contact with an outer peripheral surface, comprising: a belt stretching means contacting the outer peripheral surface of the endless belt. 4. An image fixing apparatus according to claim 3, wherein said belt stretching means is a cleaning roller for cleaning said belt surface.