JP2002304069A - Fixing unit and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt preheating system fixing unit which suppresses wrinkling and ridging of a belt due to uneven heating while shortening warm-up time and saving energy and has uniform fixing performance and to provide an image forming apparatus. SOLUTION: In the fixing unit 1, a heating roller 4 which stretches a belt 2 is obtained by forming a Teflon layer 11 on the surface of a core metal 9 by coating with Teflon and has grooves 10 in the peripheral surface in the longitudinal direction. The belt 2 comprises a polyimide resin coated with a silicone resin or a fluororesin or it is a silicone resin or fluororesin film. The grooves 10 are independent circular grooves or grooves spiraled right and left in opposite directions from the center of the roller as a boundary. The grooves 10 in the surface of the heating roller 4 and inside ribs 12 are disposed in the same positions. The heating roller 4 is produced by spinning working.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing apparatus and an image forming apparatus using an electrophotographic process, such as a copying machine, a facsimile, and a printer. More specifically, the present invention relates to a fixing apparatus of a heat fixing type and an image using the same. The present invention relates to a forming apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus, an image forming process by a fixing device of a heat fixing method is to pass a toner image formed on a recording paper together with the recording paper between a fixing roller and a pressure roller, and to apply heat to the toner. In general, the toner is melted by applying a pressure to the toner, and at the same time, the toner image is fixed on the recording paper by the pressure between the rollers. By the way, in recent years, demands for shortening the warm-up time of the image forming apparatus and saving energy have been increasing. Until now, the warm-up time could be shortened by preheating the fixing roller in advance to speed up image fixing or by increasing the capacity of the halogen heater, etc., which is the heating source of the fixing roller. While aiming for zero power consumption by
There is a demand for a fixing method without waiting time.

As one of the measures, there is a belt preheating method. The heating step and the fixing step in the heat fixing method,
It is divided into a small diameter heating roller and a fixing roller having a small heat capacity, a thin belt having a small heat capacity is stretched, and a pressure roller is pressed against the belt. As a result, it is possible to shorten the warm-up time and to fix the image with energy saving.

[0004]

However, the following problems occur in the belt preheating method. When a metal material such as aluminum, stainless steel, nickel or the like is used as the base material of the belt, 50 μm to 1 μm to satisfy the strength and workability.
A thickness of 00 μm is effective, but with this thickness, metal fatigue accumulates over a long period of use, leading to cracks.

On the other hand, there is a polyimide resin or the like which satisfies the high-temperature durability among the polymer materials. However, when the belt whose temperature has been lowered in the fixing process is heated again to the heating temperature by contact with the heating roller. The expansion causes a floating (gap) between the heating roller and the heating roller, resulting in uneven heating or, in the case of remarkable heating, wrinkling of the belt. In addition, uneven thermal expansion due to uneven heating may cause the belt to shift laterally. Further, it is necessary to reduce the thickness of the belt as much as possible in order to shorten the rise time of the heating roller. However, in the case of a belt made of a thinned polymer material, deformation such as crushing is increased due to a decrease in strength at the center. As a result, the contact pressure between the heating roller and the belt is small at the center and large at the ends, causing slack in the center along with the thermal expansion of the belt, causing wrinkles, and uneven thermal expansion in the horizontal direction. It can also cause a shift.

In view of the above problems, the present invention is directed to a belt preheating system having a uniform fixing performance, which reduces the occurrence of wrinkles and deviations due to uneven heating of the belt while shortening the warm-up time and saving energy. It is an object to provide a fixing device and an image forming apparatus.

[0007]

According to an aspect of the present invention, there is provided a fixing device used in an electrophotographic image forming apparatus, wherein the fixing device comprises at least two or more rollers. A fixing device includes a belt that is stretched and a pressure roller, and one roller that stretches the belt has a groove in a longitudinal direction of an outer peripheral surface. According to a second aspect of the present invention, there is provided a fixing device according to the first aspect, wherein one roller for stretching the belt is a heating roller.

According to a third aspect of the present invention, there is provided a fixing device according to the first or second aspect, wherein the belt is formed by coating a polyimide resin with a silicone resin or a fluorine resin. According to a fourth aspect of the present invention, there is provided the fixing device according to the first or second aspect, wherein the belt is a film of a silicone resin or a fluororesin.

According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, the groove on the outer peripheral surface of the heating roller is independent for each rotation. A fixing device. According to a sixth aspect of the present invention, in the fixing device according to any one of the first to fifth aspects, the groove on the outer peripheral surface of the heating roller has a spiral shape in the right and left directions opposite to the center. The fixing device is a feature.

According to a seventh aspect of the present invention, there is provided a fixing device according to any one of the first to sixth aspects, wherein a rib is provided on an inner surface of the heating roller. According to an eighth aspect of the present invention, in the fixing device according to any one of the first to seventh aspects, the groove on the outer peripheral surface and the rib on the inner surface of the heating roller are arranged at the same position. Fixing device.

According to a ninth aspect of the present invention, there is provided a method of manufacturing a heating roller, wherein the heating roller used in the fixing device according to any one of the first to eighth aspects is manufactured by spinning.

According to a tenth aspect of the present invention, there is provided an image forming apparatus using the fixing device according to the first aspect.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a fixing device of a belt preheating type according to the present invention. A thin belt 2 is stretched between a heating roller 4 and a fixing roller 3, and a pressure roller 8 is pressed against the belt 2 to form a fixing nip portion. The core metal 9 of the heating roller 4 is made of a metal having a high thermal conductivity such as aluminum or stainless steel, and a heater 5 as a heating source is disposed inside. As the belt 2, a polyimide resin coated with a silicone resin or a fluororesin, or a film of a silicone resin or a fluororesin is used.

The temperature of the belt 2 drops to 80 to 100 ° C. at a heating start point 6 when the belt 2 enters the heating roller 4.
On the other hand, the temperature rises to about 160 ° C. at the heating completion point 7 when the heating roller 4 is separated from the heating roller 4. Compared with the width of the base of the belt 2 at the heating start point 6, the width at the heating completion point 7 is extended by about 1 mm due to thermal expansion. At this time, if the sliding between the belt 2 and the heating roller 4 is insufficient, the belt 2 is partially lifted, which causes wrinkles.

FIG. 2 is a view showing the heating roller 4 of the present invention, and FIGS. 3A and 3B are sectional views showing the shapes of the belt and the groove. FIG. 3A shows the state at the heating start point 6 in FIG. 1, and FIG. 3B shows the state at the heating completion point 7. As shown in FIG. 2, the heating roller 4 has a groove 10 formed on the outer peripheral surface of the metal core 9, and the groove 10 is independent for each rotation. As shown in FIG. 3, the surface of the cored bar 9 is coated with Teflon to form a Teflon (registered trademark) layer 11. By the Teflon layer 11, the belt 2 and the heating roller 4 are in smooth contact with each other, and the lifting of the belt 2 can be prevented. In addition, the heated belt 2
3B, as shown in FIG. 3B, follows the shape of the groove 10 formed on the surface of the Teflon layer 11, so that the belt is prevented from floating due to thermal expansion, and the heat conductivity is improved. Can prevent the belt from shifting.

FIG. 4 is a view showing the heating roller 4 of the present invention. As shown in FIG. 4, the groove 10 has a spiral shape in the right and left directions opposite to the center. According to the shape of the groove in FIG. 4, the belt 2 is stretched by thermal expansion and at the same time, the belt 2 is pulled to both ends by the rotation of the heating roller 4, so that the lifting of the belt 2 can be prevented.

FIG. 5 is a sectional view showing an example of the shape of the groove 10. The groove 10 has a shape that can easily follow the belt 2 and has a depth that can absorb the elongation of the belt 2 base. The depth varies slightly depending on the material of the belt, but is 0.01 mm to 0.5 m.
It is desirable to set m.

FIGS. 6 and 7 are sectional views showing the rib shape of the heating roller 4. FIG. As shown in FIG. 6, by providing the ribs 12 on the inner surface of the heating roller 4, it is possible to reduce the collapse of the heating roller 4 due to the tension of the belt 2 even when the core 9 is thin. Therefore, the tension in the width direction of the belt 2 can be equalized. Further, as shown in FIG.
By providing the groove 10 on the outer peripheral surface and the rib 12 on the inner surface at the same position, the collapse of the heating roller 4 can be further reduced, and the tension in the width direction of the belt 2 can be equalized. Also, when the groove 10 on the outer peripheral surface and the rib 12 on the inner surface are provided at the same position, the concave portion on the surface of the raw tube formed in the rib 12 processing step is left after the outer diameter cutting, so that the surface groove 10 is obtained. In addition, the processing load can be reduced.

FIG. 8 is a schematic view showing a spinning method which is a method of manufacturing the heating roller 4 used in the fixing device 1 of the present invention. After forming a concave portion on the surface of the base tube by the spinning roller 13, the outer diameter is cut to form the groove 10.

FIG. 9 shows an example of an image forming apparatus using the fixing device 1 of the present invention. By using the fixing device 1 of the present invention, it is possible to prevent the belt from rising and moving in the lateral direction while shortening the warm-up time and saving energy, and to provide a uniform fixing performance.

[0021]

As described above, according to the present invention, a groove is formed on the outer peripheral surface of the heating roller while shortening the fixing time and saving energy. Therefore, the belt elongation caused by heating is absorbed by following the grooves, which can reduce the lifting of the belt from the heating roller and the occurrence of wrinkles, and at the same time,
It is possible to provide a fixing device in which the efficiency of heat transfer from the heating roller is improved and the belt is prevented from shifting laterally due to uneven heating. According to the present invention described in claim 5,
Since the groove on the outer peripheral surface of the heating roller is independent for each rotation,
The expansion of the belt due to the thermal expansion is absorbed following the groove, and the belt following the groove is resistant to lateral deviation, so that it is possible to provide a fixing device in which deviation is prevented. Further, according to the present invention, since the groove on the outer peripheral surface of the heating roller is formed in a helical shape in the right and left opposite directions from the center, the elongation of the belt due to thermal expansion is absorbed along the groove. At the same time, a pulling force acts on the left and right sides, and a fixing device that prevents wrinkling of the belt can be provided.
Further, according to the present invention, the ribs are provided on the inner surface of the thin-walled heating roller, so that the collapse of the heating roller due to the pressure from the belt is reduced, and the tension in the width direction of the belt is made more uniform. Therefore, it is possible to provide a fixing device in which the occurrence of wrinkles and the occurrence of deviation due to the slack of the belt are prevented. Further, according to the present invention, by arranging the positions of the grooves on the surface of the heating roller and the ribs on the inner surface at the same position, it is possible to provide a fixing device with a reduced processing load. Further, according to the present invention, a method of manufacturing a heating roller with a reduced processing load can be provided. Further, according to the tenth aspect of the present invention, by using the fixing device according to the first to eighth aspects of the present invention, the fixing performance is improved while shortening the warm-up time and saving energy. An image forming apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fixing device of a belt preheating type according to the present invention.

FIG. 2 is a view showing a heating roller of the present invention.

FIG. 3 is a cross-sectional view illustrating shapes of a belt and a groove.

FIG. 4 is a view showing a heating roller of the present invention.

FIG. 5 is a sectional view showing an example of the shape of a groove.

FIG. 6 is a cross-sectional view illustrating a rib shape of a heating roller.

FIG. 7 is a cross-sectional view showing a rib shape of a heating roller.

FIG. 8 is a schematic view showing a spinning method.

FIG. 9 is an example of an image forming apparatus using the fixing device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing device 2 Belt 3 Fixing roller 4 Heating roller 5 Heater 6 Heating start point 7 Heating completion point 8 Pressure roller 9 Core metal 10 Groove 11 Teflon layer 12 Rib 13 Spinning roller

Claims (10)

[Claims] 1. A fixing device used in an electrophotographic image forming apparatus, wherein the fixing device has a belt stretched by at least two or more rollers and a pressure roller, and one roller for stretching the belt. Has a groove in the longitudinal direction of the outer peripheral surface. 2. The fixing device according to claim 1, wherein one roller that stretches the belt is a heating roller. 3. The fixing device according to claim 1, wherein the belt is formed by coating a polyimide resin with a silicone resin or a fluorine resin. 4. The fixing device according to claim 1, wherein the belt is a film of a silicone resin or a fluorine resin. 5. The fixing device according to claim 1, wherein the groove on the outer peripheral surface of the heating roller is independent for each rotation. 6. The fixing device according to claim 1, wherein the groove on the outer peripheral surface of the heating roller has a spiral shape in the right and left opposite directions with respect to the center. . 7. The fixing device according to claim 1, wherein a rib is provided on an inner surface of the heating roller. 8. The fixing device according to claim 1, wherein the groove on the outer peripheral surface and the rib on the inner surface of the heating roller are arranged at the same position. 9. A method for manufacturing a heating roller, wherein the heating roller used in the fixing device according to claim 1 is manufactured by spinning. 10. An image forming apparatus using the fixing device according to claim 1.