JPH07311505A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing device capable of outputting a high quality image by preventing the increase of glossiness and a deterioration of image. CONSTITUTION:A downstream side fixing roller 40 including a halogen heater 42 and a downstream side pressure roller 41 for backing up are disposed on the downstream side in the advancing direction of a transfer material from a pair of fixing rollers composed of a fixing roller 20 including a halogen heater 22 and a pressure roller 21 disposed coming into press-contact with the fixing roller 20. The fluororesin surface of the surface layer of the fixing roller 20 on the upstream side is made smooth so that the surface roughness is <=1mum in 10 pieces average roughness Rz, to hardly stick toner and the surface of the fixing roller 40 on the downstream side is made comparatively rough so that the surface roughness is about 1-50mum in the 10 pieces average roughness Rz, to reduce the glossiness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention heats or pressurizes a toner image that is visually formed on a transfer material such as plain paper or photosensitive paper by electrophotography, electrostatic recording, magnetography and the like. The present invention relates to a fixing device for fixing.

[0002]

2. Description of the Related Art FIG. 8 is a schematic view for explaining the structure of a conventional fixing device for fixing toner on a transfer material in an electrophotographic copying machine or the like. In the apparatus shown in FIG. 8, a fixing roller 20 for fixing the toner to the transfer material and a pressure roller 21 for applying pressure to the transfer material and the toner by backup.
Form a pair of fixing rollers. The fixing roller 20 uses iron or aluminum alloy as the basis of the structure, that is, a core metal, and the surface thereof is tetrafluoroethylene resin (hereinafter referred to as PTFE) or tetrafluoroethylene-perfluorovinyl ether copolymer (hereinafter , PFA), or a fluororesin typified by PFA) is often used to coat a high-releasability layer in which a single or a composite thereof is used. Further, the pressure roller 21 has an elastic layer such as silicone rubber or fluororubber on the cored bar, and is formed by coating a highly releasable layer such as fluororesin. Further, the fixing roller 20 includes a halogen heater 22 as a heat source,
The surface temperature of the fixing roller 20 is the thermistor 2 for temperature adjustment.
While being detected by 3, the temperature is maintained at about 100 ° C. to 200 ° C. by a temperature control means such as a CPU.

The fixing roller 20 is provided with a separating claw 2 in order to prevent the transfer material from winding around the fixing roller 20.
No. 4 is provided, and oil is applied for the purpose of cleaning the residual toner adhering to the fixing roller 20 or for the purpose of applying oil for improving the releasing property between the toner and the fixing roller 20. A web 30 made of impregnated non-woven cloth is arranged so as to rub against the fixing roller 20.

The web 30 is pressed against the fixing roller 20 by the pressing roller 31, and the web 30 previously wound around the feed roller 32 is gradually wound around the winding roller 33.

[0005]

However, the following problems occur in the above-mentioned conventional fixing device. That is, the fixing roller is coated with the fluororesin as described above, and the surface thereof has a smooth surface with a ten-point average roughness Rz of about 1 μm or less. This is because no matter how the fluororesin is used, the toner is likely to adhere to the fixing roller having an uneven surface due to its mechanical frictional force.
If the toner easily adheres, problems occur such that the toner on the transfer material is peeled off and the image is disturbed, or cleaning is difficult, and the image quality of the next output image is deteriorated. Therefore, the fixing roller is required to have surface smoothness, but on the other hand, the surface smoothness causes a problem that gloss of an output image is increased. Moreover, when a relatively smooth transfer material is used, there is a problem that the smoothness of the toner surface is further increased, and as a result of increased gloss, the visual density is reduced. The decrease in visual density is not an unpleasant phenomenon and is not preferred by users of image output devices. Further, there is basically no means for solving the image deterioration in which the toner surface is rubbed by the separation claw in the fixing device according to the conventional technique.

A first invention according to the present application aims to solve the above problems and to provide a fixing device capable of outputting an image with high image quality and high quality by preventing an increase in glossiness and image deterioration. There is.

In addition to the above object, a second invention of the present application aims to provide a fixing device capable of roughening the toner surface while preventing the toner from adhering to the fixing roller. I am trying.

Further, in addition to the above objects, the third invention of the present application is, in particular, a fixing in which the surface of the toner once fixed on the transfer material can be temporarily melted for roughening. The purpose is to provide a device.

In addition to the above-mentioned object, the fourth invention of the present application, in particular, roughens the surface of the toner without adversely affecting the fixability itself of the toner once fixed on the transfer material. It is an object of the present invention to provide a fixing device that can be temporarily melted due to the above.

Further, in addition to the above-mentioned object, the fifth invention according to the present application, in particular, with respect to the temperature condition, does not adversely affect the fixability of the toner once fixed on the transfer material, and the toner surface is roughened. It is an object of the present invention to provide a fixing device that can be temporarily melted for conversion.

In addition to the above object, the sixth invention of the present application is particularly directed to roughening the toner surface without adversely affecting the fixability of the toner once fixed on the transfer material. It is an object of the present invention to provide a fixing device that can easily separate a transfer material without rubbing the toner surface when the toner is temporarily melted.

Further, in addition to the above-mentioned object, the seventh invention of the present application, especially when the toner is once fixed on the transfer material and the surface of the toner is roughened, the paper between the two steps is also provided. An object of the present invention is to provide a fixing device that does not cause clogging.

[0013]

According to the first invention of the present application, the above object is to provide a fixing roller or a fixing film rotatably arranged, and a heat source contained in the fixing roller or the fixing film. And a pressure roller arranged so as to be in pressure contact with the heat source directly to the fixing roller or through the fixing film, and the transfer material is nipped and conveyed at the pressure contact portion to transfer the transfer material. In a fixing device for fixing a visible toner image on a material by heat or pressure, a pressure roller or a pressure roller is newly provided on the downstream side of the pressure contact portion in the traveling direction of the transfer material. It has a downstream side fixing roller arranged so as to be in pressure contact with the pressure roller, and the surface of the downstream side fixing roller has a roughness of 1 to 50 μm in ten-point average roughness Rz. Achieved by

According to the second invention of the present application,
The above-mentioned purpose is the ten-point average roughness R of the surface of the downstream fixing roller.
The roughness represented by z is achieved by being larger than the roughness represented by the ten-point average roughness Rz of the surface of the fixing roller or the fixing film on the upstream side in the traveling direction of the transfer material.

Further, according to the third invention of the present application, the above-mentioned object is that the amount of heat applied by the downstream fixing roller to the transfer material and the visible toner image is higher than that of the fixing roller upstream in the traveling direction of the transfer material. It is achieved by being controlled to be small.

According to the fourth invention of the present application,
The above object is achieved by the width of the pressure contact portion between the downstream fixing roller and the pressure roller being smaller than the width of the pressure contact portion between the fixing roller or the fixing film and the pressure roller on the upstream side in the traveling direction of the transfer material.

Further, according to the fifth invention of the present application, the above object is to compare the surface temperature of the downstream fixing roller with the surface temperature of the fixing roller or the fixing film on the upstream side in the traveling direction of the transfer material. This is achieved by controlling the temperature so that the temperature is the same or a low temperature.

According to the sixth invention of the present application,
The above object is achieved by the outer diameter of the downstream fixing roller being smaller than the outer diameter of the fixing roller on the upstream side in the traveling direction of the transfer material.

Further, according to the seventh invention of the present application, the above-mentioned object is to make the rotational speeds of the fixing roller and the pressure roller on the downstream side the same as those of the fixing roller or the fixing film on the upstream side in the traveling direction of the transfer material. This is achieved by controlling the speed to be the same or higher than the rotation speed of the pressure roller.

[0020]

According to the first invention of the present application, the fixing roller or fixing film rotatably arranged is arranged so as to come into pressure contact with the heat source directly or through the fixing film. The visible toner image on the transfer material is temporarily fixed on the transfer material by being heated and pressed at the pressure contact portion formed between the pressure roller and the transfer roller. The pressure roller, or a pressure roller newly provided separately from the pressure roller, and a downstream fixing roller disposed so as to be in pressure contact with the pressure roller, the pressure roller being disposed on the downstream side in the traveling direction of the material. It is heated and pressurized again at the pressure contact portion with. Then, at this time, since the surface of the downstream fixing roller has a ten-point average roughness Rz of 1 to 50 μm, the toner surface is appropriately roughened and the smoothness is reduced,
The gloss is reduced.

According to the second invention of the present application,
Since the roughness represented by the ten-point average roughness Rz of the surface of the downstream fixing roller is larger than the roughness represented by the ten-point average roughness Rz of the surface of the fixing roller or the fixing film on the upstream side in the traveling direction of the transfer material. In the fixing roller or fixing film on the upstream side, toner adhesion is suppressed and image deterioration is prevented, and on the fixing roller on the downstream side, appropriate roughening is performed to prevent an increase in glossiness.

Further, according to the third invention of the present application, the heat quantity applied to the transfer material and the visible toner image by the fixing roller on the downstream side is smaller than that on the fixing roller on the upstream side in the traveling direction of the transfer material. Since it is controlled, only the toner surface is melted and the toner surface is roughened.

According to the fourth invention of the present application,
Since the width of the pressure contact portion of the downstream fixing roller and the pressure roller is smaller than the width of the pressure roller contact portion between the fixing roller or the fixing film and the pressure roller in the moving direction of the transfer material, it is received from the downstream fixing roller pair. The degree of heating and pressurization is smaller than that on the upstream side, and only the toner surface is melted and roughened without adversely affecting the fixability of the toner fixed on the upstream side.

Further, according to the fifth invention of the present application, the surface temperature of the downstream fixing roller is the same as or higher than the surface temperature of the fixing roller or fixing film on the upstream side in the traveling direction of the transfer material. Since the temperature is controlled to be a low temperature, only the toner surface is melted and roughened without applying excessive heat to the toner once fixed.

According to the sixth invention of the present application,
Since the outer diameter of the downstream fixing roller is smaller than the outer diameter of the fixing roller on the upstream side in the traveling direction of the transfer material, after roughening the toner surface, without rubbing the toner surface with the separation claw,
The transfer material is easily separated from the roller.

Further, according to the seventh invention of the present application, the rotation speeds of the fixing roller and the pressure roller on the downstream side are the rotation speed of the fixing roller or the fixing film and the pressure roller on the upstream side in the traveling direction of the transfer material. Since the speed is controlled to be the same or higher than the speed, the transfer material between the downstream fixing roller pair and the upstream fixing roller pair is given an appropriate tension so that Prevents a paper jam phenomenon between the pair of fixing rollers on the downstream side.

[0027]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a schematic view of a copying machine equipped with the electrophotographic technique in this embodiment.

In FIG. 2, a manuscript is placed between the manuscript table cover 1 and the platen glass 2, the manuscript is illuminated by a manuscript illumination lamp 3, and the reflected light is reflected by the reflecting mirrors 4, 5 ,. An image corresponding to the image of the original is formed on the photoconductor 9 by projecting on the photoconductor 9 using the lens 6, the lens 7 and the reflection mirror 8. In other words, this photoconductor 9
An electric charge is applied in advance by the charger 10, and an electrostatic latent image is formed by performing the above-described exposure. Then, toner is attached to the electrostatic latent image by using the developing device 11 to visualize the electrostatic latent image, and the transfer material 100 conveyed from the paper feed deck 12 is transferred to the transfer material 100 by using the transfer separation charger 13. Transfer the toner image. The transfer material 100 on which the toner image is transferred in this way passes through the conveyor belt 14 to reach the fixing device 15, and the fixing device 15 fixes the toner image on the transfer material 100, and then discharges the paper. Output to the tray 16.

FIG. 1 is a sectional view best showing the structure of the fixing device 15 according to the present invention. In the figure, the fixing roller 2
In No. 0, iron or aluminum alloy is used as the basis of the structure, that is, a core metal, and the surface thereof is covered with a high releasable layer in which a fluororesin typified by PTFE or PFA is used alone or in combination. The pressure roller 21 is configured by coating a core metal with an elastic layer such as silicone rubber or fluororubber or a highly releasable layer such as fluororesin. The outer diameters of the fixing roller 20 and the pressure roller 21 are both 60 mm, the nip width is about 10 mm, and sufficient heat and pressure are applied to the toner on the transfer material to impart a toner fixing force. As a heat source, a 1000 W halogen heater 22 is arranged inside the fixing roller 20, and based on the temperature detected by a temperature adjusting thermistor 23, which is a temperature detecting means arranged so as to contact the fixing roller 20. The temperature control means controls the energization of the halogen heater 2 to adjust the surface temperature of the fixing roller 20 to about 180 ° C. Further, the separation claw 24 is disposed on the surface of the fixing roller 20 so as to come into contact therewith to prevent the transfer material from being wrapped around the fixing roller 20. A web 30 impregnated with silicone oil is applied to the upper portion of the fixing roller 20 for the purpose of cleaning the residual toner adhering to the fixing roller 20 and applying oil for improving the releasability of the toner. A pressing roller 31 for bringing the web 30 into contact with the fixing roller 20 is installed. The web 30 has a feed roller 32.
It is pre-wound onto the winding roller 33
It is something that is rolled up.

Further, another set of fixing roller pairs is provided on the downstream side of the above-mentioned fixing roller pair. That is, the fixing roller 40 that contacts the toner surface and the pressure roller 41 for backup are arranged. The downstream fixing roller 40 has a structure in which PTFE is coated on the core metal by 25 μm, and the pressure roller 41 is made of silicone rubber of 5 m.
In this structure, 100 μm thick PFA is coated on top of m coating. The outer diameters of the downstream fixing roller 40 and the pressure roller 41 are both 30 mm, and the nip width is about 4 mm. By providing the halogen heater 42 of 300 W as a heat source and the thermistor 43 for temperature adjustment, the surface temperature of the downstream fixing roller 40 is about 120 ° C. in the same manner as the upstream fixing roller pair. Adjusted. In addition, a cleaning roller 44 formed by winding a felt-like heat resistant non-woven material into a roller shape is also provided above the downstream fixing roller 40 for the purpose of cleaning the toner attached to the downstream fixing roller 40. There is.

Since the surface of the fluororesin, which is the surface layer of the upstream fixing roller 20, is intended to fix the unfixed toner on the transfer material with sufficient heat and pressure, the toner is unlikely to adhere. In addition, it has a smooth surface with a surface roughness of 1 μm or less in terms of ten-point average roughness Rz. On the other hand, the surface of the fixing roller 40 on the downstream side has a ten-point average roughness Rz of 1 to 50 μm, preferably 2 to 10 for the purpose of changing the glossiness, not for the purpose of increasing the fixing force between the toner and the transfer material. It has a relatively rough surface of about 10 μm. The roughening of the surface is performed by sandblasting or honing or lathing the core metal of the fixing roller 40, applying a primer containing a fluororesin, baking it, and then applying a fluororesin and baking it again. There is. The surface of the fluororesin after baking may be carried out by the above-mentioned rough surface technique. Since the toner is firmly fixed to the transfer material by receiving sufficient heat and pressure by the upstream fixing roller pair, the downstream fixing roller having a rough surface on the transfer material comes into contact with the toner. However, the harmful effect of peeling off the toner is extremely small.

Therefore, the downstream fixing roller pair is required to have an optimum ability to temporarily melt the toner surface on the transfer material. Therefore, the fixing roller pair on the downstream side has a smaller outer diameter and nip width than the upstream side, lowers the surface temperature of the fixing roller, or reduces the amount of heat applied to the transfer material and the toner. Is important. In other words, it is significant in the present invention to perform sufficient fixing on the upstream side and optimally adjust the image quality on the downstream side.

FIG. 3 is a conceptual diagram illustrating a cross section of the toner at the fixing stage. In the figure, the toner A in the unfixed stage is a state in which toner particles are simply transferred. Since each toner particle is not subjected to heat and pressure, it contains a large number of voids and the surface is highly uneven. However, after passing through the fixing roller 20 which is the fixing means on the upstream side,
Since the fixing roller 20 has high smoothness, the toner B fixed to the transfer material has very few surface irregularities. Then, according to the present invention, the fixing roller 4 which is the downstream fixing unit.
In the output image C after passing 0, only the toner surface of the toner B can be roughened due to the surface property of the downstream fixing roller 40.

The effects of the present invention are shown in Table 1. The table shows the glossiness when black toner is transferred to a transfer material having a basis weight of 128 g / m ^{2 at} the maximum density. The measuring device has an incident angle of 60 °
A gloss meter (HORIBA handy gloss meter) having a reflection angle of 60 ° was used.

[0036]

[Table 1]

From the table, in the case of a single fixing roller pair, when the ten-point average roughness Rz of the surface is increased, the glossiness is lowered,
It can be seen that the releasability of the toner deteriorates. Therefore, the present invention is the only fixing device that can achieve both glossiness and toner releasability.

FIG. 4 is a schematic diagram for explaining the glossiness of the toner surface at the fixing stage in FIG. The toner has a fixing force due to the fact that the individual toners are connected by heat and pressure and also entangled with the transfer material, but the surface thereof has a slight light ray reflectance even with the black toner. Therefore, the toner B that has passed through the fixing roller 20 on the upstream side in the drawing has a smooth surface of the fixing roller 20, so that the toner surface is also smooth. Then, the effect of so-called specular reflection having an equal reflection angle with respect to the incident angle of the light ray is increased. On the other hand, at the stage of the output image C, since it has the same surface property as the surface of the downstream fixing roller 40, irregular reflection occurs and the effect of specular reflection is reduced. As a result, it is possible to output an image that does not cause unpleasant gloss.

In addition, since the downstream fixing roller according to the present invention does not require a large outer diameter, the transfer material can be smoothly separated from the fixing roller without providing a separation claw. For this reason, the scratches caused by the separation claws received on the upstream side are remelted by the downstream fixing roller pair, and there is also an advantage that scratches are erased and reduced.

If the downstream fixing roller pair is rotated several% faster than the upstream fixing roller pair, a proper tension of the downstream fixing roller pair can be applied to the transfer material.

As a result, the image quality deterioration can be further reduced by the separation claw 24, and the paper jam phenomenon is less likely to occur between the pair of upstream and downstream fixing rollers.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the first embodiment, the fixing roller pair is provided in two stages, but in the present embodiment, as shown in FIG. 5, only one pressure roller for backup is provided. Therefore, it is more cost effective than the first embodiment.

In the figure, both the upstream side fixing roller 20 and the small diameter downstream side fixing roller 40 are in contact with the pressure roller 21. The downstream fixing roller 40 is a 0.7 mm thick iron roller, has a PTFE layer of 20 μm on the surface, and has a small heat capacity because it is a thin roller. The downstream fixing roller 40 according to this embodiment has a surface with a ten-point average roughness Rz of about 5 μm. Inside the downstream fixing roller 40, the first
Instead of the heater used in the above embodiment, heat is received via the pressure roller 21. Therefore, compared to the first embodiment, the number of components is reduced by the amount of the pressure roller and the heater, and the cost is excellent. Moreover, there is no heater on the downstream side, which is advantageous in terms of power consumption. Further, since the two fixing rollers are close in physical distance, it is possible to use a single cleaning means as shown in the figure.
That is, cleaning and oil application are efficiently performed by the pressing roller 31 that brings the web 30 into contact with the upstream fixing roller 20 and the pressing roller 45 that brings the back surface of the web 30 into contact with the downstream fixing roller 40. It will be possible.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those in the above embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the second embodiment, as a method of guiding the heat from the heater on the upstream side to the downstream side, one pressure roller is used as the heat conducting medium, but in this embodiment, as shown in FIG. Receives heat due to its unique structure.

In the figure, reference numeral 50 denotes a thin metal heat transfer roller, which has a small heat capacity.
Is in contact with the downstream pressure roller 41. The heat transfer roller 50 is movably supported by a support,
The reciprocating motion means (not shown) can be brought into and out of contact with the upstream pressure roller 21. The contact / separation operation of the heat transfer roller 50 is performed based on the temperature detected by the temperature adjusting thermistor 43 of the downstream fixing roller pair, and the heat transfer roller 50 is brought into contact with or separated from the pressure roller 21. The downstream fixing roller pair is adjusted to a predetermined temperature. In this embodiment, the temperature of the fixing roller on the downstream side is 100 ° C.
I am trying. Since the upstream pressure roller 21 and the downstream pressure roller 41 rotate at the same speed as each other, the heat transfer roller 50 follows the two rollers 21 and 41, but slips on each of them. It will rotate while waking up. The downstream side pressure roller 41 has a hollow iron core having a thickness of 3 mm, a silicone rubber coating of 2 mm, and a PFA coating of 50 μm to reduce the heat capacity and suppress temperature fluctuation as much as possible. It is configured to do.

As described above, in this embodiment, it is possible to adjust the optimum temperature of the downstream fixing roller with only the upstream heater, and it is possible to suppress the power consumption.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. The same parts as those in the above embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, in order to obtain a desired glossiness,
It is possible to apply or release the pressing force of the downstream fixing roller pair, which is shown in FIG. In the figure, the fixing means on the upstream side is not the fixing roller pair according to the above-described embodiment, but a film fixing device for applying heat from the contact heater through the seamless cylindrical film 60. The cylindrical film 60 is made of polyimide resin and PT.
A thin layered body made of FE, the inner surface of which is controlled by a resistance heating element 62 surrounded by a heat insulator 61 and a temperature control thermistor (not shown) to apply heat to the transfer material on which the toner is placed. The cylindrical film 60 is transported by the driving roller 63 at a speed approximately equal to the moving speed of the transfer material, and is properly tensioned by the tension roller 64.

At the position opposite to the resistance heating element 62 with the cylindrical film 60 sandwiched therebetween, the pressure roller 21 contacts the resistance heating element 62 through the cylindrical film 60 to back up the transfer material carrying the toner. Has been done. Even in the above film fixing device, roughening the outer surface of the cylindrical film 60 is not preferable from the viewpoint of obtaining releasability from the toner, and requires a surface property of 10 μm or less in ten-point average roughness Rz. . As a result, the gloss of the solid image is increased, giving the user a visually low-density impression.

Therefore, also in this embodiment, the above problem is solved by installing a fixing roller pair for reducing gloss on the downstream side. Further, the significance of this embodiment is that the downstream fixing roller 40 can apply or release the pressing force to the downstream pressure roller 41, and the desired gloss can be selected. is there. The method of applying or releasing the pressing force is performed by moving or rotating the support 70 of the fixing roller 40 with the electromagnetic solenoid 71. A signal for applying or releasing the pressing force is provided as a switch in the user operation unit (not shown), and this signal can reduce the gloss when the downstream fixing roller 40 is pressed. Become.

[0053]

As described above, the first aspect of the present application
According to the invention, a fixing roller or a fixing film rotatably arranged, a pressure roller arranged so as to come into pressure contact with a heat source directly on the fixing roller or through the fixing film, After the visible toner image on the transfer material is once fixed on the transfer by the fixing roller or the heat source contained in the fixing film, the pressure roller, or A pressure roller newly provided in addition to the pressure roller and a downstream fixing roller arranged so as to be in pressure contact with the pressure roller are provided, and heating and pressing are performed again at the pressure contact portion of the roller pair. Since the surface of the downstream fixing roller has a ten-point average roughness Rz of 1 to 50 μm, the toner surface can be appropriately roughened, and the releasability between the toner and the fixing roller can be maintained. Reduce smoothness, light It can be a desirable value sex.

According to the second invention of the present application,
Since the roughness represented by the ten-point average roughness Rz of the surface of the downstream fixing roller is larger than the roughness represented by the ten-point average roughness Rz of the surface of the fixing roller or the fixing film on the upstream side in the traveling direction of the transfer material. While maintaining the releasability to the toner, it is possible to carry out an appropriate surface roughening, and the glossiness can be set to a desired value.

Further, according to the third invention of the present application, the amount of heat applied to the transfer material and the visible toner image by the fixing roller on the downstream side is smaller than that of the fixing roller on the upstream side in the traveling direction of the transfer material. Since it is controlled, only the toner surface can be melted, and the toner surface can be appropriately roughened.

According to the fourth invention of the present application,
Since the width of the pressure contact portion of the downstream fixing roller and the pressure roller is smaller than the width of the pressure roller contact portion between the fixing roller or the fixing film and the pressure roller in the moving direction of the transfer material, it is received from the downstream fixing roller pair. The degree of heating and pressurization is smaller than that on the upstream side, and proper melting and roughening of only the toner surface can be performed without adversely affecting the fixability of the toner fixed on the upstream side.

Further, according to the fifth invention of the present application, the surface temperature of the downstream fixing roller is the same as or lower than the surface temperature of the fixing roller or fixing film on the upstream side in the traveling direction of the transfer material. Since the temperature is controlled to be a low temperature, only the toner surface can be melted and roughened without applying excessive heat to the toner once fixed.

According to the sixth invention of the present application,
Since the outer diameter of the downstream fixing roller is smaller than the outer diameter of the fixing roller on the upstream side in the traveling direction of the transfer material, after roughening the toner surface, without rubbing the toner surface with the separation claw,
The transfer material can be easily separated from the roller and the image quality is not deteriorated.

Further, according to the seventh invention of the present application, the rotation speeds of the fixing roller and the pressure roller on the downstream side are the rotation speed of the fixing roller or the fixing film and the pressure roller on the upstream side in the traveling direction of the transfer material. Since it is controlled to have the same speed or a higher speed than the speed, it is possible to apply an appropriate tension to the transfer material between the downstream fixing roller pair and the upstream fixing roller pair, It is possible to prevent image quality deterioration and paper jamming.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a fixing device according to a first exemplary embodiment of the present invention.

FIG. 2 is a schematic view of an electrophotographic copying machine according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating the glossiness of the toner surface in the first embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating the glossiness of the toner surface in the first embodiment of the present invention.

FIG. 5 is a sectional view showing a configuration of a fixing device according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing the structure of a fixing device according to a third embodiment of the present invention.

FIG. 7 is a sectional view showing the arrangement of a fixing device according to the fourth embodiment of the present invention.

FIG. 8 is a cross-sectional view of a fixing device in the related art.

[Explanation of symbols]

 20 upstream fixing roller 21 upstream pressure roller 22 upstream halogen heater (heat source) 40 downstream fixing roller 41 downstream pressure roller 60 cylindrical film (fixing film) 62 resistance heating element (heat source) 100 transfer material

Claims (7)

[Claims] 1. A fixing roller or a fixing film rotatably arranged, a heat source contained in the fixing roller or the fixing film, and a pressure contact with the heat source directly or through the fixing film. And a pressure roller arranged so that the transfer material is nipped and conveyed at the pressure contact portion to fix the visible toner image on the transfer material by heat or pressure. On the downstream side of the transfer material in the traveling direction, there is provided a downstream fixing roller arranged so as to come into pressure contact with the pressure roller or a pressure roller newly provided separately from the pressure roller. The fixing device is characterized in that the surface of the downstream fixing roller has a ten-point average roughness Rz of 1 to 50 μm. 2. The ten-point average roughness Rz of the surface of the downstream fixing roller is represented by the ten-point average roughness Rz of the surface of the fixing roller or fixing film on the upstream side in the traveling direction of the transfer material. The fixing device according to claim 1, wherein the fixing device has a roughness larger than the roughness. 3. The amount of heat applied by the downstream fixing roller to the transfer material and the visible toner image is controlled to be smaller than that of the upstream fixing roller in the traveling direction of the transfer material. Fixing device. 4. The width of the pressure contact portion between the downstream fixing roller and the pressure roller is smaller than the width of the pressure contact portion between the fixing roller or the fixing film and the pressure roller on the upstream side in the moving direction of the transfer material. The fixing device according to 1. 5. The surface temperature of the downstream fixing roller is controlled so as to be equal to or lower than the surface temperature of the fixing roller or fixing film on the upstream side in the traveling direction of the transfer material. The fixing device according to claim 1. 6. The fixing device according to claim 1, wherein the outer diameter of the downstream fixing roller is smaller than the outer diameter of the fixing roller on the upstream side in the traveling direction of the transfer material. 7. The rotational speeds of the fixing roller and the pressure roller on the downstream side are equal to or higher than the rotational speeds of the fixing roller or the fixing film and the fixing film on the upstream side in the traveling direction of the transfer material. The fixing device according to claim 1, wherein the fixing device is controlled so that