JP2000347526A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fixing device which is capable of decreasing the number of maintenance times by well executing the self-cleaning of rollers of a fixing device. SOLUTION: An oil coating application roller 4 is installed to a heating roller 2. A layer added with a photocatalyst is formed on the front layer of the heating roller 2 and a light source 8 for irradiating the surface of the layer with visible light or UV rays is disposed. A combustion reaction is induced in the bondable dirt on the surface of the heating roller 2 by the active oxygen, etc., generated by the irradiation of the photocatalyst with the visible light or UV rays and the dirt adheres in the form of particles as small as invisible to the eyes on transfer paper P, by which the dirt is discharged. The release property of the heating roller is greatly improved by the trace silicone oil applied by the oil coating application roller 4 is a result of the superhydrophilic effect by the photocatalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device mounted on an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly, to a heat roller type fixing device.

[0002]

2. Description of the Related Art An unfixed image (an image formed by a toner made of a heat-fusible resin or the like) mounted on an image forming apparatus such as a copying machine, a printer, or a facsimile and transferred onto a recording medium such as a transfer sheet. A heating roller (fixing roller) and a pressure roller are brought into pressure contact with each other, and the recording medium is passed between the two rollers. A heat roller type fixing device for fixing a toner image is well known.

FIG. 5 is a sectional view showing an example of a conventional heat roller type fixing device. The fixing device 20 shown in FIG. 1 includes a heating roller (fixing roller) in a frame 21.
22 and a pressure roller 23. The heating roller 22 incorporating the heat source 25 is driven to rotate in the direction of the arrow by a driving unit (not shown), and the pressing roller 23 is pressed against the heating roller 22 and rotates following the heating roller 22. The heating roller 22 and the pressure roller 23 have a multilayer structure as shown in FIGS.

That is, the heating roller 2 shown in FIG.
6 includes a sleeve 22b for maintaining the rigidity and storing heat, and a release layer 22a formed on the sleeve 22b and in contact with the unfixed toner T to transfer heat.
The pressure roller 23 shown in (b) has a nip N (FIG. 5) between the sleeve 23c that maintains the rigidity and stores heat and the heating roller 22 formed on the sleeve 23c when coming into contact with the heating roller 22. An elastic body layer 23b for forming
The release layer 10 formed on the elastic layer 23b and forming a surface layer
3a.

The transfer paper P on which the unfixed toner T is transferred is conveyed by conveying means 31 of the image forming apparatus, and guided between the heating roller 22 and the pressure roller 23 by the guide member 26. The transfer paper P includes a heating roller 22 and a pressure roller 23.
When the sheet passes through the nip N between the rollers, the unfixed toner image on the transfer sheet is fixed by heat and pressure. Thereafter, the transfer paper is separated from the heating roller 22 by the separation claw 27 and discharged from the discharge port 29 to the outside of the fixing device.

Generally, a fixing device of a heat roller type is
It is often used in an image forming apparatus using a powder toner, in which unfixed toner is melted by the heat of a heating roller and fused to transfer paper by the pressure of a heating roller and a pressure roller. Usually, the surface layer of the heating roller is made of PFA (tetrafluoroethylene-per
fluoro alkylvinyl ether copolymer), PTFE (pol
y tetra fluoro ethylene), FEP (flourinated eth)
It is made of a material with good releasability, such as ethylene propylene copolymer).

However, when a large number of transfer papers (including other recording media such as an OHP film) are passed, the surface of the roller becomes rough, and a binding-modified organic substance, paper powder, or a mixture thereof, of which toner has been denatured. For example, they may adhere to the mold and the releasability may be reduced. When the releasability decreases, the offset phenomenon in which the toner adheres to the heating roller increases, so that the snow starts to adhere, and finally, most of the toner image is offset and the normal fixing operation is not performed.

Similarly, in the pressure roller, dirt adheres to the roller over time, and abnormalities such as paper jam due to winding of the transfer paper and stain on the back of the transfer paper occur.

Conventionally, in order to prevent such abnormalities, a releasing oil such as silicone oil is applied to the surface of the heating roller to enhance the releasability, or a cleaning roller or a web is brought into contact with the cleaning roller to remove dirt. Removal has been done. Further, for example, in the invention described in JP-A-6-19357, a method has been proposed in which offset toner is pulverized into fine particles and returned to transfer paper.

However, the method of providing the oil application mechanism and the cleaning mechanism has a problem that the cost is increased due to the complicated configuration of the apparatus, and maintenance work such as oil supply and replacement of the cleaning member is increased.

Further, the silicone oil which is generally used because of its low cost has poor affinity with the release layer of the heating roller, and requires a certain amount or more to exhibit the effect of enhancing the release property. . Therefore, it is conceivable to increase the affinity by using a fluorine-based oil or a mixture of silicone oil and a fluorine-based oil. However, there is a problem that the cost of the oil is significantly increased.

[0012]

Therefore, the present inventor has proposed:
As a method without an oil application mechanism or a cleaning mechanism, Japanese Patent Application Laid-Open No. 9-244444 has proposed a technique of providing a self-cleaning effect by providing a layer containing a photocatalyst on the surface layer of a heat roller pair.

However, transfer paper, which is frequently used in recent years, has a large amount of calcium carbonate, talc, clay, etc. added to the paper in order to suppress pulp consumption. Is increasing very much. For this reason, it is difficult to cope with only the photocatalytic action, and the problem that the life of the roller is shortened has newly arisen.

The present invention solves the above-mentioned problems in a conventional fixing device utilizing photocatalysis, and can reduce the number of maintenance operations by performing simple self-cleaning of the rollers of the fixing device at a low cost with a simple structure. It is an object to provide a fixing device.

[0015]

According to the present invention, there is provided a recording medium having a heating roller and a pressure roller pressed against the heating roller, wherein the recording medium carries an unfixed image between the two rollers. In a heat roller type fixing device for fixing an unfixed image, an applying member for applying release oil to the heating roller is provided, and at least one of the heating roller and the pressing roller is provided on the surface of the roller. This problem can be solved by forming a layer to which a photocatalyst that acts as a catalyst by irradiating light is added, and providing a light source for irradiating visible light or ultraviolet light on the surface of this layer.

According to another aspect of the present invention, there is provided a heating roller having a heating roller and a pressure roller pressed against the heating roller, wherein a recording medium carrying an unfixed image is passed between the two rollers. In a fixing device of a heat roller type for fixing an unfixed image, a coating member for applying a release oil to the heating roller is provided, and the heating roller maintains rigidity and stores heat, and a sleeve for storing heat. A release layer formed thereon and performing heat transfer in contact with the unfixed image, and a photocatalyst that acts as a catalyst by irradiating light to the release layer is added to the release layer. It is proposed to provide a light source for irradiating visible light or ultraviolet light on the surface.

According to another aspect of the present invention, there is provided a heating roller having a heating roller and a pressure roller pressed against the heating roller, wherein a recording medium carrying an unfixed image is passed between the two rollers. In a heat roller type fixing device that fixes an unfixed image, a coating member that applies release oil to the heating roller is provided, and the pressure roller is a sleeve that maintains rigidity and stores heat. An elastic layer is formed on the sleeve to form a nip between the heat roller and the heat roller when the sleeve is in contact with the heat roller, and a release layer is formed on the elastic layer and forms a surface layer. A photocatalyst which acts as a catalyst by irradiating light to this release layer is added, and it is proposed to provide a light source for irradiating visible light or ultraviolet light on the surface of the pressure roller.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view schematically showing an example of a fixing device according to the present invention. A fixing device 10 shown in FIG. 1 includes a heating roller (fixing roller) in a frame 1.
2 and a pressure roller 3. The heating roller 2 is driven to rotate in the direction of the arrow by a driving unit (not shown), and the pressure roller 3 is pressed against the heating roller 2 and rotates following the heating roller 2. The heating roller 2 has a built-in heat source 5 (for example, a halogen lamp).

The fixing device 10 is rotated by the heating roller 2 and rotates to apply oil for release to the heating roller 2. The fixing device 10 applies the transfer paper P to the heating roller 2 and the pressure roller 3. The heating roller 2 includes a guide member 6 for guiding the sheet P between them, a separation claw 7 for separating the fixed transfer paper P from the heating roller 2, and a light source 8 for irradiating the surface of the heating roller 2 with visible light or ultraviolet light. . The light source 8 is supported by the frame 1 of the fixing device.

The transfer paper P on which the unfixed toner T is transferred is conveyed by the conveying means 11 of the image forming apparatus, and guided between the heating roller 2 and the pressure roller 3 by the guide member 6. The transfer paper P is conveyed while being sandwiched between the heating roller 2 and the pressure roller 3, and the unfixed toner T is melted by the heat of the heating roller 2 and is fused to the transfer paper P by the pressure of the nip N between both rollers. After that, the transfer paper P is separated from the heating roller 2 by the separation claw 7 and is discharged from the discharge port 9 to the outside of the fixing device.

The heating roller 2 in the present embodiment is similar to the heating roller shown in FIG.
As shown in FIG. 1, the sleeve 2b is formed of an aluminum sleeve 2b which maintains the rigidity and stores heat, and a release layer 2a formed on the sleeve 2b and in contact with the unfixed toner T to conduct heat. The release layer 2a is formed of a material in which a small amount of a photocatalyst is added to a mixture of an additive which imparts conductivity and abrasion resistance with a fluororesin PFA as a main component.

In this embodiment, TiO is used as the photocatalyst.
₂ (titanium dioxide) is used, but if it is a photocatalyst,
ZnO, SnO ₂ , SrTiO ₃ , Bi ₂ O ₃ , Fe ₂
O ₃ , CdTe, MoS ₂ , CdS, or a mixture thereof can be used. Aluminum is used for the sleeve 2b and fluorine resin PFA is used for the main component of the release layer 2a. Examples of the material for the sleeve 2b include iron and the like which maintain rigidity and store heat in addition to aluminum.
As a main component of the release layer 2a, PTFE, FEP, which is the same fluororesin, in addition to the fluororesin PFA, may be mentioned. The light source 8 includes a light emitting portion 8a and a reflecting portion 8b. Since the photocatalyst is efficiently activated mainly by light having a wavelength in the ultraviolet region, a fluorescent tube of about several watts is used as the light emitting portion 8a. I have.

The oil application roller 4 has a silicone oil stored therein, and when driven and rotated in contact with the heating roller 2, oil oozes out from its surface layer and a very small amount of oil oozes on the surface of the heating roller 2. Is applied.

With the use of the fixing device, the binding-modified organic substance of the toner, paper powder, or a mixture thereof adheres to the heating roller 2. However, in the present embodiment, a photocatalyst is added to the release layer 2a that forms the surface layer of the heating roller 2, and a light source 10 that irradiates the release layer 2a with visible light or ultraviolet light.
Is provided, the binding dirt on the surface of the heating roller 2 causes a combustion reaction by active oxygen or the like generated by irradiating the photocatalyst with visible light or ultraviolet light, thereby causing carbon dioxide, water, and other low-molecular substances. The particles are decomposed into oxides, become invisible small particles, adhere to the transfer paper P, and are discharged. In addition, the affinity between the release layer and the applied silicone oil is significantly increased by the superhydrophilic action of the photocatalyst (contact angle method), so that a very small amount of silicone oil applied by the oil application roller 4 separates the heating roller. The moldability is greatly improved, and it is possible to cope with the deterioration of the degree of dirt.

As described above, in the fixing device 10 of the present embodiment, the release layer 2a to which the photocatalyst is added is formed on the surface layer of the heating roller 2, and the light source for irradiating the surface of the heating roller 2 with visible light or ultraviolet light. 10 and the oil application roller 4 for applying a very small amount of oil to the heating roller 2, so that the dirt such as toner and paper powder adhering to the surface of the heating roller 2 is decomposed at any time and the paper is transferred. Self-cleaning is performed by transferring to paper. Therefore, even if a large number of transfer papers are passed, the roller surface will not be roughened, and the binding-modified organic substance of the toner, paper powder, or a mixture thereof will not adhere.
It is possible to prevent the releasability from lowering. Further, since an offset phenomenon in which toner adheres to the heating roller 2 can be prevented, a toner image can be prevented from being offset due to snowball-like contamination, and a normal fixing operation can be maintained.

Further, the self-cleaning of the heating roller 2 can be performed well without providing a cleaning device for the heating roller. Therefore, even when using a transfer paper containing a large amount of calcium carbonate, talc, clay, etc. Dirt on the surface can be efficiently removed. Since no cleaning device is provided, the number of maintenance operations such as replacement of the cleaning member can be reduced.

Further, although the release oil is consumed in a very small amount, the consumption amount can be reduced in each step as compared with the prior art. Therefore, the number of maintenance operations for oil supply can be reduced. Further, it is possible to prevent oil from adhering to the transfer paper.

The mold releasability can be maintained for a long time even when the amount of the silicone oil applied is extremely reduced by the superhydrophilic action of the photocatalyst. In addition, the photocatalyst activates a chemical change only, and does not change itself. The effect of the fluorescent lamp of several watts, which consumes a small amount of power, lasts semipermanently, so that an increase in cost due to a complicated mechanism can be suppressed.

Next, a second embodiment of the present invention will be described. FIG. 3 is a cross-sectional configuration diagram schematically showing a second embodiment of the present invention. In the fixing device shown in this figure, a surface layer to which a photocatalyst is added is formed on the pressure roller 3, and a light source 18 for irradiating the pressure roller 3 with visible light or ultraviolet light is provided. No photocatalyst was added to the surface layer of the heating roller 2 and no light source for the heating roller 2 was provided. The other configuration is the same as that of the above-described embodiment of FIG.

The pressure roller 3 in the present embodiment is similar to the one shown in FIG.
As shown in FIG. 3, a nip N (FIG. 3) is formed between an aluminum sleeve 3c that maintains rigidity and stores heat, and a heating roller formed on the sleeve 3c and abutting on the heating roller 2. Elastic layer 3b, and a release layer 3a formed on the elastic layer 3b and serving as a surface layer. The release layer 3a is formed of a material in which a small amount of a photocatalyst is added to a mixture of an additive for imparting conductivity and abrasion resistance, which is mainly composed of a fluororesin PFA.

In this embodiment, TiO is used as the photocatalyst.
₂ (titanium dioxide) is used, but if it is a photocatalyst,
ZnO, SnO ₂ , SrTiO ₃ , Bi ₂ O ₃ , Fe ₂
O ₃ , CdTe, MoS ₂ , CdS, or a mixture thereof can be used. Aluminum is used for the sleeve 3c, heat-resistant rubber is used for the elastic layer 3b, and the release layer 3a is used.
Fluororesin PFA is used as the main component of the sleeve 3c, but the material of the sleeve 3c may be iron or the like that maintains rigidity in addition to aluminum. The main component of the release layer 3a may be the same as the main component other than the fluororesin PTA. PTFE, F which is fluororesin
EP and the like. The light source 18 includes a light emitting portion 18a and a reflecting portion 18b. Since the photocatalyst is efficiently activated mainly by light having a wavelength in the ultraviolet region, a fluorescent tube of about several watts is used as the light emitting portion. .

Since the fixing operation is performed in the same manner as in the embodiment of FIG. 1, the description is omitted. In the present embodiment, a photocatalyst is added to the release layer 3a that forms the surface layer of the pressure roller 3, and a light source 18 that irradiates the release layer 3a with visible light or ultraviolet light.
Is provided, the binding dirt on the surface of the pressure roller 3 causes a combustion reaction by active oxygen or the like generated by irradiating the photocatalyst with visible light or ultraviolet light to cause carbon dioxide, water, and other low molecular weight substances. Is decomposed into oxides, and becomes invisible small particles, adheres to the transfer paper P, and is discharged. In addition, the affinity between the release layer and the applied silicone oil is significantly increased due to the superhydrophilic action of the photocatalyst (contact angle method). Therefore, a very small amount of silicone oil greatly improves the releasability of the pressure roller. Even if the degree of dirt deteriorates, it is possible to respond.

Further, even when the fixing device is used for a long time, dirt does not adhere to the pressure roller 3, and it is possible to prevent abnormalities such as paper jam due to winding of the transfer paper and back stain of the transfer paper. Furthermore, there is no need to provide a separate cleaning device.Although it consumes a very small amount of oil, the amount of oil consumption can be significantly reduced compared to the past, and the catalyst only activates chemical changes and does not change itself, Since a fluorescent lamp of several watts with low power consumption lasts semipermanently, the problems such as an increase in cost due to a complicated mechanism and an increase in maintenance work such as oil supply and replacement of a cleaning device can be solved.

As described above, the present invention relates to a first embodiment in which an oil applying mechanism for applying oil to a heating roller is provided, a surface layer to which a photocatalyst is added is provided on the heating roller, and a light source for irradiating light to the surface layer is provided. A description will be given by using the embodiment and a second embodiment in which an oil application mechanism for applying oil to a heating roller is provided, a surface layer to which a photocatalyst is added is provided on a pressure roller, and a light source for irradiating light to the surface layer is provided. However, the present invention is not limited to this. In addition to providing an oil application mechanism for applying oil to the heating roller, providing a surface layer to which a photocatalyst is added to both the heating roller and the pressure roller and irradiating the surface with light. It is also possible to provide a light source.

In the case where a surface layer to which a photocatalyst is added is provided on both the heating roller and the pressure roller to provide a light source for irradiating the surface layer with light, one light source irradiates both the heating roller and the pressure roller with light. However, since the paper is passed between the heating roller and the pressure roller, it is more effective to provide a light source separately for both rollers.

Further, in each of the above-described embodiments, an example in which a heat source is incorporated inside the heating roller has been described, but the heating method of the heating roller is not limited to this. That is, a method in which the heating roller is heated by a heater such as a halogen lamp from outside the heating roller may be used. Alternatively, the present invention can be applied to a self-heating type heating roller in which a heating layer such as an electric resistor is provided on the heating roller so that the heating roller itself generates heat. Further, an induction coil is provided, and an alternating current (high-frequency current) is applied to the induction coil to generate an induction magnetic flux (magnetic field). The magnetic field generates an induction current in the conductive layer of the heating roller, and the induction current is generated. The present invention can also be applied to an induction heating type heating roller in which the heating roller generates heat by Joule heat.

[0037]

As described above, according to the fixing device of the first aspect, the oil applying member for applying the release oil to the heating roller is provided, and the photocatalyst is added to the surface layer of the heating roller or the pressure roller. Since a light source for irradiating visible light or ultraviolet light is provided on this surface,
Self-cleaning is performed by, for example, decomposing the dirt such as toner and paper powder attached to the surface of the roller on which the layer to which the photocatalyst is formed is formed and transferring the dirt to the transfer paper to be passed. As a result, even when a large number of transfer papers are passed, the roller surface is not roughened, and the modified binding organic substance of the toner, paper powder, or a mixture thereof does not adhere, thereby preventing a decrease in releasability. be able to. In addition, even when the amount of the release oil applied is extremely reduced due to the superhydrophilic action of the photocatalyst, the release property can be maintained for a long time.

In particular, when the photocatalyst-added layer is formed on the heating roller, the offset phenomenon in which the toner adheres to the heating roller can be prevented, so that the offset of the toner image due to the snowman-type stain is reduced. Prevent,
Normal fixing operation can be maintained.

Further, when the photocatalyst-added layer is formed on the pressure roller, the pressure roller also prevents abnormalities such as paper jam due to wrapping of the paper and stain on the back of the paper due to contamination due to use over time. can do.

Since the self-cleaning of the roller can be performed satisfactorily without separately providing a cleaning device, even when transfer paper containing a large amount of calcium carbonate, talc, clay or the like is used, dirt on the roller surface can be efficiently removed. be able to. Since no cleaning device is provided, the number of maintenance operations such as replacement of the cleaning member can be reduced.

Further, although the release oil is consumed in a very small amount, the consumption can be reduced in each step as compared with the prior art. Therefore, the number of maintenance operations for oil supply can be reduced. Further, it is possible to prevent oil from adhering to the transfer paper.

Even when the amount of the silicone oil applied is extremely reduced by the superhydrophilic action of the photocatalyst, the releasability can be maintained for a long time. In addition, the photocatalyst activates a chemical change only, and does not change itself. The effect of the fluorescent lamp of several watts, which consumes a small amount of power, lasts semipermanently, so that an increase in cost due to a complicated mechanism can be suppressed.

According to the second aspect of the present invention, the oil applying member for applying the release oil to the heating roller is provided.
Since a layer to which a photocatalyst is added is formed on the surface of the heating roller and a light source for irradiating visible light or ultraviolet light is provided on this surface, dirt such as toner and paper powder attached to the surface of the heating roller is decomposed as needed. The self-cleaning is performed by, for example, shifting to a transfer sheet to be passed. for that reason,
Even if a large number of transfer papers are passed, the surface of the heating roller will not be roughened, and the denatured binding organic substance, paper powder, or a mixture thereof will not adhere. Can be. In addition, even when the amount of the release oil applied is extremely reduced due to the superhydrophilic action of the photocatalyst, the release property can be maintained for a long time.

Since the offset phenomenon in which the toner adheres to the heating roller can be prevented, the toner image can be prevented from being offset due to snowball-like contamination, and the normal fixing operation can be maintained.

Further, since the self-cleaning of the roller can be performed well without providing a separate cleaning device for the heating roller, even when a transfer paper containing a large amount of calcium carbonate, talc, clay or the like is used, the contamination of the roller surface can be prevented. Can be efficiently removed. Since no cleaning device is provided, the number of maintenance operations such as replacement of the cleaning member can be reduced.

Further, although the release oil is consumed in a very small amount, the consumption can be reduced in each step as compared with the prior art. Therefore, the number of maintenance operations for oil supply can be reduced. Further, it is possible to prevent oil from adhering to the transfer paper.

The release property can be maintained for a long time even when the amount of the silicone oil applied is extremely reduced by the superhydrophilic action of the photocatalyst. In addition, the photocatalyst activates a chemical change only, and does not change itself. The effect of the fluorescent lamp of several watts, which consumes a small amount of power, lasts semipermanently, so that an increase in cost due to a complicated mechanism can be suppressed.

According to the third aspect of the present invention, a layer to which a photocatalyst is added is formed on the surface of the pressure roller, and a light source for irradiating visible light or ultraviolet light is provided on this surface. Self-cleaning is performed by, for example, decomposing dirt such as toner and paper dust as needed and transferring the dirt to transfer paper to be passed. As a result, even if a large number of transfer papers are passed, the surface of the pressure roller is not roughened, and the modified binding organic substance of the toner, paper powder, or a mixture thereof does not adhere, so that the releasability is deteriorated. Can be prevented. In addition, even when the amount of the release oil applied is extremely reduced due to the superhydrophilic action of the photocatalyst, the release property can be maintained for a long time.

Further, it is possible to prevent abnormalities such as a paper jam due to the winding of the paper and a stain on the back of the paper due to the adhesion of the stain due to use over time. Furthermore, self-cleaning of the roller is performed well without the need for a separate cleaning device on the pressure roller, so even when using transfer paper to which a large amount of calcium carbonate, talc, clay, etc. is added, the roller surface can be efficiently cleaned. It can be removed well. Since no cleaning device is provided, the number of maintenance operations such as replacement of the cleaning member can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an example of a fixing device according to the present invention.

FIG. 2 is a partial cross-sectional view illustrating a configuration of a heating roller of the fixing device.

FIG. 3 is a sectional view schematically showing a second embodiment of the present invention.

FIG. 4 is a partial cross-sectional view illustrating a configuration of a pressure roller of the fixing device.

FIG. 5 is a sectional view showing an example of a conventional heat roller type fixing device.

FIG. 6 is a partial cross-sectional view illustrating a configuration of a heating roller and a pressure roller of the fixing device.

[Explanation of symbols]

 1,21 fixing device frame 2,22 heating roller (fixing roller) 3,23 pressure roller 4 oil application roller 5,25 heat source 8,18 light source N nip P transfer paper T unfixed toner

Claims (3)

[Claims] 1. A heat roller system comprising a heating roller and a pressure roller pressed against the heating roller, wherein a recording medium carrying an unfixed image is passed between the two rollers to fix the unfixed image. In the fixing device, an application member that applies release oil to the heating roller is provided, and a photocatalyst that functions as a catalyst by irradiating light to at least one roller surface of the heating roller and the pressure roller is provided. A fixing device comprising: a layer to which an additive is added; and a light source for irradiating visible light or ultraviolet light on the surface of the layer. 2. A heat roller system comprising a heating roller and a pressure roller pressed against the heating roller, wherein a recording medium carrying an unfixed image is passed between the two rollers to fix the unfixed image. In the fixing device, an application member that applies release oil to the heating roller is provided, and the heating roller is configured to maintain rigidity and store heat, and is formed on the sleeve to contact the unfixed image. A photocatalyst that acts as a catalyst by irradiating light is added to the release layer, and a light source that emits visible light or ultraviolet light is provided on the surface of the heating roller. A fixing device. 3. A heat roller system comprising a heating roller and a pressure roller pressed against the heating roller, wherein a recording medium carrying an unfixed image is passed between the two rollers to fix the unfixed image. In the fixing device, an application member that applies release oil to the heating roller is provided, and the pressure roller is a sleeve that maintains rigidity and stores heat, and is formed on the sleeve and abuts on the heating roller. Sometimes an elastic layer for forming a nip between the heating roller and a release layer formed on the elastic layer and forming a surface layer, and the release layer is exposed to light. A fixing device comprising a photocatalyst acting as a catalyst, and a light source for irradiating visible light or ultraviolet light on the surface of the pressure roller.